Harbin, China

The Harbin Institute of Technology is a research university and a member of the C9 League in China consisting of three campuses, which nearly span the country from north to south: the Harbin campus in Heilongjiang Province, the Weihai campus in Shandong Province and the Shenzhen graduate school in Guangdong Province.HIT undertakes research and numerous projects covered by official secrets which may have a bearing on its international ranking, although it is widely recognized as one of the top universities in the country, especially when it comes to local science and engineering league tables. HIT is one of only ten universities in the world that have designed, built, and launched their own satellites . It made the largest contribution to the success of the Shenzhou series spacecraft and Kuaizhou series spacecraft. One minor planet is named after the Harbin Institute of Technology and nicknamed "Hagongda Star" by the International Astronomical Union for HIT's achievements in science and engineering. Wikipedia.


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Patent
Harbin Institute of Technology | Date: 2014-12-26

Aircraft engine rotors traditionally have low coaxiality after assembly. This is solved by the methods and devices described herein, having advantages that the rotors have high coaxiality after assembly, reduced vibration, easy installation, high flexibility, and improved engine performance. A measurement method and device use an air flotation rotary shaft system determining a rotary reference. An induction synchronizer determines angular positioning of a turntable. Using a four probe measurement device, a radial error of a rotor radial assembly surface and an inclination error of an axial mounting surface are extracted and an influence weight value of the rotor on the coaxiality of assembled rotors is obtained. All rotors required for assembly are measured and an influence weight value of each on the coaxiality of the assembled rotors is obtained. Vector optimization is performed on the weight value of each rotor and an assembly angle of each rotor is obtained.


A five-degree-of-freedom adjustment and positioning method and apparatus for assembly/measurement of rotor and stator of an aircraft engine; said method comprises adjusting a plane motion and a rotation of a tested piece through composite motion comprising five degrees of freedom: a 360 rotatory motion around a Z axis, a plane motion along an X axis and a plane motion along a Y axis, a rotatory motion around the X axis and a rotatory motion around the Y axis; said apparatus comprises: a clamping mechanism (1), a turning platform component (A), a translational platform component (B) and a rotational platform component (C). The present invention designs a five-degree-of-freedom adjustment and positioning method and apparatus having properties of large load bearing, high precision and high stiffness, thus improving assembly efficiency and measurement accuracy of the aircraft engine.


Patent
Harbin Institute of Technology | Date: 2015-04-10

A high-power bi-directional non-recovery spring magnetic valve including permanent magnets has an upper magnetic circuit part and lower magnetic circuit part symmetrically disposed and connected together via an armature connection rod and a housing connection ring, the upper magnetic circuit part comprises an upper iron core, an upper housing, an upper coil, an upper annular permanent magnet, an upper yoke iron and an upper push rod, the lower magnetic circuit part comprises a lower iron core, a lower housing, a lower coil, a lower annular permanent magnet, a lower yoke iron and a lower push rod. The magnetic valve comprising permanent magnets realizes bistable-state magnetic retaining, and has an adjustable retaining force for permanent magnet adjustment, quick response, and high output force.


A method for measuring a dip angle of oppositely crossly placed paired quartered ring-quartered circle nested polar plates. An annular coplanar capacitance measuring head of a sensor unit consists of four quarter round metal plates and four quarter circular-ring-shaped metal plates, the eight metal plates are coplanar and concentric with one another, and a quarter round metal plate and a quarter circular-ring-shaped metal plate corresponding to the same sector angle form a capacitor. Two annular coplanar capacitance measuring heads are arranged on two round insulating substrates, the two round insulating substrates are used as two bottom surfaces of a cylindrical container, the cylindrical container is transversely arranged, and an insulating liquid equal to volume of the cylindrical container is injected into the cylindrical container in a sealing manner. Potential leads extract potentials of the sixteen metal plates and are connected to an input end of a capacitance measuring unit, and the capacitance measuring unit is connected to a dip measuring unit. When the cylindrical container tilts, the relative positions of the two annular coplanar capacitance measuring heads and the insulating liquid are changed, and a dip angle value can be calculated by measuring the change of a capacitance value. Also disclosed is a device for measuring a dip angle of oppositely crossly placed paired quartered ring-quartered circle nested polar plates.


An optical window based on an array of rings and sub-rings having a triangular and orthogonal mixed distribution is suited for electromagnetic shielding. The array has metal rings of the same diameter acting as basic rings closely arranged according to an equilateral triangular and two-dimensional orthogonal square mixed arrangement and is loaded on an optical window transparent substrate surface. Adjacent basic rings are connected externally tangentially. Metal sub-rings are arranged within each basic ring and connected thereto internally tangentially. Each basic ring and its sub-rings constitute a basic unit. At tangential connection locations of the rings, wires overlap or metal is provided to ensure reliable electrical connections between connected rings, thus all rings are conductive. The metal grid structure significantly reduces non-uniformity of grid high-order diffracted light intensity distribution, thereby causing stray light distribution caused by diffraction to be more uniform and imaging to be less affected.


Optical windows based on a multi-period master-slave nested ring array of concentric rings are suited for electromagnetic shielding. A metal grid of the ring array has basic rings, concentric sub-ring pairs, secondary sub-rings, filling rings, concentric modulation ring pairs, and modulation sub-rings. Basic rings and concentric modulation ring pairs form a two-dimensional orthogonal array. External rings of concentric modulation ring pairs are externally tangentially connected to basic rings. Concentric sub-ring pairs and filling rings are arranged within basic rings, secondary sub-rings are arranged within concentric sub-ring pairs, and modulation sub-rings are arranged within concentric modulation ring pairs. Where rings are tangentially connected, wires overlap or metal ensures reliable electrical connections between connected rings, thus all rings are conductive. The metal grid structure significantly reduces non-uniformity of grid high-order diffracted light intensity distribution, causing stray light distribution caused by diffraction to be more uniform and imaging to be less affected.


Patent
Harbin Institute of Technology | Date: 2017-03-29

A fast-response thermoplastic shape-memory polyimide and a preparation method thereof, related to a polyimide and a preparation method thereof. The present invention aims to solve the problem in high-temperature conditions of slow shape recovery poor stability, and poor mechanical properties of a shape-memory polymer prepared by utilizing an existing method. The structural formula of the polyamide of the present invention is as represented by formula (I). The preparation method is: 1. preparation of a diamine solution; 2. preparation of an anhydride-terminated high molecular weight polyamic acid; 3. preparation of a viscous sol-gel; and, 4. preparation of the thermoplastic shape-memory polyimide. The thermoplastic shape-memory polyimide prepared per the present invention is provided with a very fast shape recovery rate and improved shape-memory effect. The present invention is applicable in the field of polyimide preparation.


Liang X.,Peking University | Li X.,Harbin Institute of Technology | Jing L.,Harbin Institute of Technology | Yue X.,Harbin Institute of Technology | Dai Z.,Peking University
Biomaterials | Year: 2014

Photodynamic therapy (PDT) is a site-specific treatment of cancer involving the administration of a photosensitizer (PS) followed by the local light activation. Besides efficient PSs, image guidance is essential for precise and safe light delivery to the targeting site, thus improving the therapeutic effectiveness. Herein, we report the fabrication of theranostic porphyrin dyad nanoparticles (TPD NPs) for magnetic resonance imaging (MRI)-guided PDT cancer therapy, where the inner metal free porphyrin functions as a photosensitizer for PDT while the outer Mn-porphyrin serve as an MRI contrast agent. Covalent attachment of porphyrins to TPD NPs avoids premature release during systemic circulation. In addition, TPD NPs ([U+FF5E]60nm) could passively accumulate in tumors and be avidly taken up by tumor cells. The PDT and MRI capabilities of TPD NPs can be conveniently modulated by varying the molar ratio of metal free porphyrin/Mn-porphyrin. At the optimal molar ratio of 40.1%, the total drug loading content is up to 49.8%, 31.3% for metal free porphyrin and 18.5% for Mn-porphyrin. The laser light ablated the tumor completely within 7 days in the presence of TPD NPs and the tumor growth inhibition was 100%. The relaxivities were determined to be 20.58s-1mm-1 for TPD NPs, about four times as much as that of Mn-porphyrin (5.16s-1mm-1). After 24h intravenous injection of TPD NPs, MRI images showed that the whole tumor area remained much brighter than surrounding healthy tissue, allowing to guide the laser light to the desired tumor site for photodynamic ablation. © 2014 Elsevier Ltd.


Gao Z.,Zhejiang Normal University | Zhao X.,Harbin Institute of Technology
Optics and Lasers in Engineering | Year: 2012

In order to meet the needs of in-process measurement in mechanical engineering, we proposed a dynamic speckle method (DSM) for predicting the roughness of moving weak-scattering surfaces. The statistical properties of the dynamic speckle intensity produced by the rough surface were studied. A mathematical model of the recorded dynamic speckle image is built. Then a linear relationship was established between the surface height variance and the natural logarithm of a roughness characteristic parameter extracted from the dynamic speckle image. The theoretical derivations and computer simulations demonstrate that the present method is simple in measuring principle, insensitive to the surface correlation length and resistant to the machine tool vibration, which indicates that the DSM has the potential for in-process application. Finally, an experiment was given. © 2011 Elsevier Ltd. All rights reserved.


Yang R.,Shandong University | Liu G.-P.,University of South Wales | Liu G.-P.,Harbin Institute of Technology | Shi P.,Victoria University of Melbourne | And 3 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

This paper studies the problem of predictive output feedback control for networked control systems (NCSs) with random communication delays. A networked-predictive-control scheme is employed to compensate for the network-induced delay. Furthermore, the time-varying predictive controller with mixed random delays for networked systems is introduced. Then, the system is formulated as a Markovian jump system. New techniques are presented to deal with the distributed delay in the discrete-time domain. Based on the analysis of closed-loop NCSs, the designed predictive time-varying output feedback controller can guarantee system stability. Simulation example demonstrates the compensation for random communication delays and data loss in networked systems using the proposed predictive scheme. © 1982-2012 IEEE.


Zhao X.,Bohai University | Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of South Wales | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2014

In this paper, novel stability conditions for Takagi-Sugeno (T-S) fuzzy systems are presented. The so-called nonquadratic membership-dependent Lyapunov function is first proposed, which is formulated in a higher order form of both the system states and the normalized membership functions than existing techniques in the literature. Then, new membership-dependent stability conditions are developed by the new Lyapunov function approach. It is shown that the conservativeness of the obtained criteria can be further reduced as the degree of the Lyapunov function increases. Two numerical examples are given to demonstrate the effectiveness and less conservativeness of the obtained theoretical results. © 1993-2012 IEEE.


Ma Y.,Harbin Institute of Technology | Liang X.,Peking University | Tong S.,Georgia Institute of Technology | Bao G.,Georgia Institute of Technology | And 3 more authors.
Advanced Functional Materials | Year: 2013

A novel multifunctional drug-delivery platform is developed based on cholesteryl succinyl silane (CSS) nanomicelles loaded with doxorubicin, Fe 3O4 magnetic nanoparticles, and gold nanoshells (CDF-Au-shell nanomicelles) to combine magnetic resonance (MR) imaging, magnetic-targeted drug delivery, light-triggered drug release, and photothermal therapy. The nanomicelles show improved drug-encapsulation efficiency and loading level, and a good response to magnetic fields, even after the formation of the gold nanoshell. An enhancement for T2-weighted MR imaging is observed for the CDF-Au-shell nanomicelles. These nanomicelles display surface plasmon absorbance in the near-infrared (NIR) region, thus exhibiting an NIR (808 nm)-induced temperature elevation and an NIR light-triggered and stepwise release behavior of doxorubicin due to the unique characteristics of the CSS nanomicelles. Photothermal cytotoxicity in vitro confirms that the CDF-Au-shell nanomicelles cause cell death through photothermal effects only under NIR laser irradiation. Cancer cells incubated with CDF-Au-shell nanomicelles show a significant decrease in cell viability only in the presence of both NIR irradiation and a magnetic field, which is attributed to the synergetic effects of the magnetic-field-guided drug delivery and the photothermal therapy. Therefore, such multicomponent nanomicelles can be developed as a smart and promising nanosystem that integrates multiple capabilities for effective cancer diagnosis and therapy. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ma Y.,Harbin Institute of Technology | Yeh L.-H.,National Yunlin University of Science and Technology | Qian S.,Old Dominion University
Electrochemistry Communications | Year: 2014

Analytical expressions for the pH-regulated ionic current/conductance in a cylindrical nanopore are derived for taking into account practical effects of multiple ionic species, surface chemistry reactions, and electroosmotic flow. Our model is verified by the experimental data of the conductance in the silica nanopore available in the literature. The validated analytical models are applicable to investigate electrokinetic ion transport, and to design the next-generation nanopore-based devices. © 2014 Elsevier B.V.


Xue S.,Old Dominion University | Yeh L.-H.,National Yunlin University of Science and Technology | Ma Y.,Harbin Institute of Technology | Qian S.,Old Dominion University
Journal of Physical Chemistry C | Year: 2014

Many experimental results demonstrated that ion transport phenomena in nanofluidic devices are strongly dependent on the surface charge property of the nanochannel. In this study, active control of the surface charge property and the streaming current, generated by a pressure-driven flow, in a pH-regulated nanochannel using a field effect transistor (FET) are analyzed for the first time. Analytical expressions for the surface charge property and the streaming current/conductance have been derived taking into account multiple ionic species, surface chemistry reactions, and the Stern layer effect. The model is validated by the experimental data of the streaming conductance in the silica nanochannel available in the literature. Results show that the pH-dependent streaming conductance of the gated silica nanochannel is consistent with its modulated zeta potential; however, the salt concentration-dependent streaming conductance might be different from the zeta potential behavior, depending on the solution pH and the gate potential imposed. The performance of the field effect modulation of the zeta potential and the streaming conductance is significant for lower solution pH and salt concentration. The results gathered are informative for the design of the next-generation nanofluidics-based power generation apparatus. © 2014 American Chemical Society.


Hu Q.,Harbin Institute of Technology | Xiao B.,Harbin Institute of Technology | Friswell M.I.,University of Swansea
IET Control Theory and Applications | Year: 2011

This study investigates the robust fault-tolerant attitude control of an orbiting spacecraft with a combination of unknown actuator failure, input saturation and external disturbances. A fault-tolerant control scheme based on variable structure control is developed that is robust to the partial loss of actuator effectiveness, where the actuators experience a reduced actuation but are still active. The results are then extended to the case in which some of the actuators fail completely, although some redundancy in actuation is assumed. In contrast to traditional fault-tolerant control methods, the proposed controller does not require knowledge of the actuator faults and is implemented without explicit fault detection, separation and accommodation processes. Moreover, the designed controller rigorously enforces actuator saturation constraints. The associated stability proof is constructive and develops a candidate Lyapunov function that shows the attitude and the angular velocities converge asymptotically to zero. Simulation studies are used to evaluate the closed-loop performance of the proposed control solution and illustrate its robustness to external disturbances, unknown actuator faults and even input saturation. © 2011 The Institution of Engineering and Technology.


Su X.,Chongqing University | Wu L.,Harbin Institute of Technology | Shi P.,University of Adelaide | Shi P.,Victoria University of Melbourne | Song Y.-D.,Chongqing University
Automatica | Year: 2014

This paper investigates the problem of Hankel-norm output feedback controller design for a class of T-S fuzzy stochastic systems. The full-order output feedback controller design technique with the Hankel-norm performance is proposed by the fuzzy-basis-dependent Lyapunov function approach and the conversion on the Hankel-norm controller parameters. Sufficient conditions are established to design the controllers such that the resulting closed-loop system is stochastically stable and satisfies a prescribed performance. The desired output feedback controller can be obtained by solving a convex optimization problem, which can be efficiently solved by standard numerical algorithms. Finally, a Henon map system is used to illustrate the effectiveness of the proposed techniques. © 2014 Elsevier Ltd. All rights reserved.


Li H.,Bohai University | Gao H.,Harbin Institute of Technology | Gao H.,King Abdulaziz University | Shi P.,University of Adelaide | And 2 more authors.
Automatica | Year: 2014

This paper is concerned with the stabilization problem for a class of Markovian stochastic jump systems against sensor fault, actuator fault and input disturbances simultaneously. In the proposed approach, the original plant is first augmented into a new descriptor system, where the state vector, disturbance vector and fault vector are assembled into the state vector of the new system. Then, a novel augmented sliding mode observer is presented for the augmented system and is utilized to eliminate the effects of sensor faults and disturbances. An observer-based mode-dependent control scheme is developed to stabilize the resulting overall closed-loop jump system. A practical example is given to illustrate the effectiveness of the proposed design methodology. © 2014 Elsevier Ltd. All rights reserved.


Zhao X.,China University of Petroleum - East China | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide | Zhang L.,Harbin Institute of Technology
Systems and Control Letters | Year: 2012

The stabilization problem for a class of switched linear systems with average dwell time (ADT) switching is reinvestigated in this paper. State-feedback controllers are designed, which takes the more practical case, asynchronous switching, into account, where the so-called "asynchronous switching" indicates that the switchings between the controllers and the system modes are in the presence of a time delay. By combining the asynchronous switching, an improved stabilization approach is given, and existence conditions of the controllers associated with the corresponding ADT switching are formulated in terms of a set of linear matrix inequalities. A numerical example is given to show the validity and potential of the obtained theoretical results. © 2012 Elsevier B.V. All rights reserved.


Ge J.,Harbin Institute of Technology
Energy Procedia | Year: 2011

Landfill gas emission associated with waste management is becoming significant environmental and energy issues in China. Currently, China is the world's largest municipal solid waste generator and approximate 80% of the generated waste is disposed in landfills. Landfill gas is a byproduct of anaerobic decomposition of organic waste and is typically comprised of methane and carbon dioxide. Due to the high heat value of methane, landfill gas has emerged as an easily available energy source. However, landfill gas collection is not common in most conventional landfills in China. Bioreactor technology provides an environmentally friendly way to increase landfill gas generation in a shorter period of time, which makes landfill gas collection more efficiently and economically. Model simulations were conducted to compare landfill gas generation in both conventional and bioreactor landfills and to estimate CO 2 emission reduction under various conditions in this study. The results indicate that bioreactor technology can provide a promising approach for waste management in China. © 2011 Published by Elsevier Ltd.


Lin C.-W.,Harbin Institute of Technology | Hong T.-P.,National University of Kaohsiung | Hong T.-P.,National Sun Yat - sen University
Wiley Interdisciplinary Reviews: Data Mining and Knowledge Discovery | Year: 2013

The Internet has become an unlimited resource of knowledge, and is thus widely used in many applications. Web mining plays an important role in discovering such knowledge. This mining can be roughly divided into three categories, including Web usage mining, Web content mining, and Web structure mining. Data and knowledge on the Web may, however, consist of imprecise, incomplete, and uncertain data. Because fuzzy-set theory is often used to handle such data, several fuzzy Web-mining techniques have been proposed to reveal fuzzy and linguistic knowledge. This paper reviews these techniques according to the three Web-mining categories above-fuzzy Web usage mining, fuzzy Web content mining, and fuzzy Web structure mining. Some representative approaches in each category are introduced and compared. © 2013 John Wiley & Sons, Inc.


Jin Y.,Harbin Institute of Technology | Wang J.,Peking University | Ke H.,Harbin Institute of Technology | Wang S.,Peking University | Dai Z.,Peking University
Biomaterials | Year: 2013

Theranostic microcapsules were successfully fabricated by introducing gold nanoparticles into poly(lactic acid) microcapsules through a double-microemulsion method, followed by depositing graphene oxide onto the microcapsule surface via electrostatic layer-by-layer self-assembly technique. It was proved that the obtained microcapsules could serve as a contrast agent to simultaneously enhance US imaging and X-ray CT imaging greatly both invitro and invivo. In addition, the invivo therapeutic examinations showed that the microcapsule was an effective agent for photothermal therapy of cancer. The near-infrared laser light ablated the tumor completely within 9 days in the presence of the microcapsules and the tumor growth inhibition was 83.8%. The combination of real-time ultrasound with 3-D computed tomography through a single microcapsule agent is very helpful for accurately interpreting the obtained images, identifying the size and location of the tumor, as well as guiding and monitoring the photothermal therapy. Simultaneously, the effectiveness of photothermal therapy could be evaluated by the combined US and CT imaging enhanced by the microcapsule agent. Such a versatile microcapsule system might bring opportunities to the next generation of multimodal imaging guided cancer therapy. © 2013.


Zha Z.,Harbin Institute of Technology | Yue X.,Harbin Institute of Technology | Ren Q.,Peking University | Dai Z.,Harbin Institute of Technology
Advanced Materials | Year: 2013

Uniform polypyrrole (PPy) nanoparticles are fabricated from a facile one-step aqueous dispersion polymerization. Owing to their high photothermal conversion efficiency and photostability compared with the well-known Au nanorods, as well as their good colloidal stability and biocompatibility, the resulting PPy nanoparticles can used as a novel promising photothermal ablation coupling agent for targeted treatment of cancer. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Jiang J.J.,Peking University | Ye B.,Harbin Institute of Technology | Ma X.M.,Peking University
Energy Policy | Year: 2014

The Shenzhen ETS is the first urban-level "cap-and-trade" carbon emissions trading scheme to operate in China. This paper gives an overview of the economic and emissions situation in Shenzhen and focuses on the development of the Shenzhen ETS regulatory framework. It is devised as an ETS with an intensity-based cap, output-based allocation and a market for trading of allowances. The design of the Shenzhen ETS attaches great importance to coordinate the dynamic relationships between economic growth, industrial transition and emissions control. The cap and its allocation are determined by carbon intensity reduction targets and economic output, with an aim to slow down emissions growth while mitigating shocks from economic fluctuation and industrial adjustment to market stability. The Shenzhen ETS features extensive coverage consisting of three types of regulated entities and four categories of covered emissions, in order to control carbon emissions by both improving energy efficiency and restraining growing energy demand. A competitive game theory method is created for allocation of free allowances to manufacturing enterprises. Mechanisms for carbon offsets and market stabilization are developed to promote active and orderly trading in the carbon market. Moreover, several challenges and their policy choices are detailed for the development of the Shenzhen ETS. © 2014 Elsevier Ltd.


Mei J.,Harbin Institute of Technology | Ren W.,University of California at Riverside | Chen J.,City University of Hong Kong | Ma G.,Harbin Institute of Technology
Automatica | Year: 2013

In this paper, we study the distributed coordination problem for multiple Lagrangian systems in the presence of parametric uncertainties under a directed graph without using neighbors' velocity information in the absence of communication. We consider two cases, namely, the distributed containment control problem with multiple stationary leaders and the leaderless synchronization problem. In both cases, distributed adaptive control algorithms without using neighbors' velocity information are proposed. The control gains in the algorithms are varying with distributed updating laws. Furthermore, necessary and sufficient conditions on the directed graph are presented, respectively, such that all followers converge to the stationary convex hull spanned by the stationary leaders asymptotically in the containment control problem and the systems synchronize asymptotically in the leaderless synchronization problem. Finally, simulation examples are provided to show the effectiveness of the proposed control algorithms. © 2013 Elsevier Ltd. All rights reserved.


Liu M.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide
Automatica | Year: 2013

This paper investigates the problem of fault estimation and fault-tolerant control against sensor failures for a class of nonlinear Itô stochastic systems with simultaneous input and output disturbances. By using a new descriptor sliding mode approach, an accurate estimation of the system states, fault vector and disturbances can be obtained simultaneously. Based on the state estimates, an integral-type sliding mode control scheme against faults and disturbances is proposed to stabilize the resulting fault system. It is shown that the reachabilities of the proposed sliding mode surfaces can be guaranteed in both the state estimate space and the estimation error space simultaneously under the designed control schemes. Finally, a numerical example is presented to illustrate the effectiveness and applicability of the proposed technique. © 2013 Elsevier Ltd. All rights reserved.


Su X.,Harbin Institute of Technology | Wu L.,Harbin Institute of Technology | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide | Shi P.,University of South Wales
IEEE Transactions on Industrial Informatics | Year: 2013

The paper is concerned with the problem of distributed fuzzy filter design for a class of sensor networks described by discrete-time T-S fuzzy systems with time-varying delays and multiple probabilistic packet losses. In sensor network, each individual sensor can receive not only its own measurement but also its neighboring sensors' measurements according to the interconnection topology to estimate the system states. Our attention is focused on the design of distributed fuzzy filters to guarantee the filtering error dynamic system to be mean-square asymptotically stable with an average mathscr H performance. Sufficient conditions for the obtained filtering error dynamic system are proposed by applying an comparison model and the scaled small gain theorem. Based on the measurements and estimates of the system states and its neighbors for each sensor, the solution of the parameters of the distributed fuzzy filters is characterized in terms of the feasibility of a convex optimization problem. Finally, an illustrative example is provided to illustrate the effectiveness of the proposed approaches in sensor networks. © 2005-2012 IEEE.


Liu M.,Harbin Institute of Technology | Cao X.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide
IEEE Transactions on Fuzzy Systems | Year: 2013

This paper deals with the problem of fault estimation and fault-tolerant control for Takagi-Sugeno (T-S) fuzzy stochastic systems with sensor failures, where the system under consideration contains Itô-type stochastic disturbances. A new robust observer technique is presented to obtain the estimates of the system states and the sensor faults simultaneously, and a fuzzy fault-tolerant control scheme is developed to guarantee the closed-loop system to be exponentially stable in mean square. Sufficient conditions are obtained for the existence of admissible controllers, and it is shown that the reachability of the sliding-mode dynamics can be guaranteed under the proposed control techniques. Finally, a numerical example is provided to illustrate the effectiveness and applicability of the theoretic results obtained. © 1993-2012 IEEE.


Yang J.,Nanjing University of Science and Technology | Chu D.,National University of Singapore | Zhang L.,Hong Kong Polytechnic University | Xu Y.,Harbin Institute of Technology
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

A sparse representation-based classifier (SRC) is developed and shows great potential for real-world face recognition. This paper presents a dimensionality reduction method that fits SRC well. SRC adopts a class reconstruction residual-based decision rule, we use it as a criterion to steer the design of a feature extraction method. The method is thus called the SRC steered discriminative projection (SRC-DP). SRC-DP maximizes the ratio of between-class reconstruction residual to within-class reconstruction residual in the projected space and thus enables SRC to achieve better performance. SRC-DP provides low-dimensional representation of human faces to make the SRC-based face recognition system more efficient. Experiments are done on the AR, the extended Yale B, and PIE face image databases, and results demonstrate the proposed method is more effective than other feature extraction methods based on the SRC. © 2012 IEEE.


Zhao X.,Bohai University | Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of Adelaide | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, the problems of robust stability and stabilization are investigated for a class of continuous-time uncertain systems. The uncertainties in the model are state-dependent and belong to a polytopic convex set, as can be found in many electronic circuits and some other applications. The global asymptotic stability conditions for such systems are first established by the classic common quadratic Lyapunov function approach. To reduce conservativeness, a particular class of nonquadratic parameter-dependent Lyapunov functions is introduced, by which improved robust stability conditions for the underlying systems are also derived. Based on the stability criteria, a static output feedback controller is then designed for the system. The effectiveness of the proposed approaches is illustrated by a numerical example, and the applicability of our theoretical findings is simultaneously demonstrated by modeling, analysis, and control design for a class of electronic circuits. © 1982-2012 IEEE.


Mei J.,Harbin Institute of Technology | Ren W.,University of California at Riverside | Ma G.,Harbin Institute of Technology
Automatica | Year: 2012

In this paper, we study the distributed containment control problem for networked Lagrangian systems with multiple dynamic leaders in the presence of parametric uncertainties under a directed graph that characterizes the interaction among the leaders and the followers. We propose a distributed adaptive control algorithm combined with distributed sliding-mode estimators. A necessary and sufficient condition on the directed graph is presented such that all followers converge to the dynamic convex hull spanned by the dynamic leaders asymptotically. As a byproduct, we show a necessary and sufficient condition on leaderless consensus for networked Lagrangian systems under a directed graph. Numerical simulation results are given to show the effectiveness of the proposed control algorithms. © 2012 Elsevier Ltd. All rights reserved.


Wu L.,Harbin Engineering University | Su X.,Harbin Institute of Technology | Shi P.,University of Adelaide | Shi P.,Victoria University of Melbourne
IEEE Transactions on Automatic Control | Year: 2014

This paper is concerned with the induced ℓ2 dynamic output feedback controller (DOFC) design problem for discrete-time Markovian jump repeated scalar nonlinear systems. By employing both the switching-sequence dependent Lyapunov function approach and the positive definite diagonally dominant Lyapunov function technique, a sufficient condition is first established, which guarantees the underlying system to be stochastically stable with an induced ℓ2 disturbance attenuation performance. Then the desired full- or reduced-order DOFCs are designed by using projection approach. Cone complementarity linearization procedure is employed to cast the nonconvex feasibility problem into a sequential minimization problem. Finally, a numerical example is presented to show the effectiveness of the proposed methods. © 2013 IEEE.


Liu M.,Harbin Institute of Technology | Zhang L.,Harbin Institute of Technology | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide | Karimi H.R.,University of Agder
IEEE Transactions on Industrial Electronics | Year: 2014

This paper investigates the problems of state observer design and observer-based integral sliding-mode control (SMC) for a class of Itô stochastic systems subject to simultaneous input and output disturbances. A new type of sliding-mode-based descriptor observer method is developed to approximate the system state and disturbance vectors. An integral-type SMC scheme is proposed based on the state estimation to stabilize the overall system. The main contributions of this approach are as follows: 1) The desired estimations of state and disturbance vectors can be obtained simultaneously, and 2) in the designed sliding-mode observer, the integral term of the Itô stochastic noise is eliminated in the proposed sliding-mode surface by a matrix design; thus, the reachability of the sliding-mode surface is strictly guaranteed. Finally, the proposed approach is applied to the disturbance reconstruction problem of an F-18 aircraft model to illustrate the effectiveness and applicability. © 1982-2012 IEEE.


Li Y.,Harbin Institute of Technology | Li Y.,University of Macau | Huang J.,National University of Singapore | Tang H.,University of Macau
IEEE Transactions on Automation Science and Engineering | Year: 2012

This paper presents a novel compliant parallel XY micromotion stage driven by piezoelectric actuators (PZT). With the purpose to obtain complete kinematic decoupling and good stiffness performance, the stage is designed using a symmetric 4-PP structure in which double four-bar flexure is chosen as the prismatic joint. Matrix method is employed to establish the compliance model of the mechanism. Based on the model, dynamic analysis is investigated after static analysis is carried out. The dimensions of the mechanism are optimized using the particle swarm optimization (PSO) algorithm in order to maximize the natural frequencies. Finite-element analysis (FEA) result indicates that the mechanism has an almost linear force-deflection relationship, high first natural frequency (720.52 Hz), and ideal decoupling property. To cope with the nonlinearities such as hysteresis that exists in the PZT, the control system is constructed by a proportional-integral-derivative (PID) feedback controller with a feedforward compensator based on Preisach model. The fabricated prototype has a 19.2 μm × 8.8 μm rectangular workspace with coupling less than 5%. The result of the closed-loop test shows that the XY stage can achieve positioning, tracking and contouring tasks with small errors. © 2004-2012 IEEE.


Li F.,Harbin Institute of Technology | Shi P.,University of Adelaide | Shi P.,Victoria University of Melbourne | Wu L.,Harbin Institute of Technology | Zhang X.,Heilongjiang University
IEEE Transactions on Fuzzy Systems | Year: 2014

This paper is concerned with the problems of D-stability and nonfragile control for a class of discrete-time descriptor Takagi-Sugeno (T-S) fuzzy systems with multiple state delays. D-stability criteria are proposed to ensure that all the poles of the descriptor T-S fuzzy system are located within a disk contained in the unit circle. Furthermore, a sufficient condition is presented such that the closed-loop system is regular, causal, and D-stable, in spite of parameter uncertainties and multiple state delays. The corresponding solvability conditions for the desired fuzzy-rule-dependent nonfragile controllers are also established. Finally, examples are given to show the effectiveness and advantages of the proposed techniques. © 1993-2012 IEEE.


Zhang Y.,Harbin Institute of Technology
IEEE Transactions on Geoscience and Remote Sensing | Year: 2011

Need for a priori knowledge of the components comprising each pixel in a scene has set the endmember determination, rather than the endmember abundance quantification, as the primary focus of many unmixing approaches. In the absence of the information about the pure signatures present in an image scene, which is often the case, the mean spectra of the pixel vectors, directly extracted from the scene, are usually used as the pure signatures' spectra. This approach which is mathematically optimized for unmixing problems with a priori known information ignores some statistical properties of the extracted samples and leads to a suboptimal solution for real situations. This paper proposes a novel learning-based unmixing-to-classification conversion model to treat the abundance quantification task as a classification problem. Support vector machine, as an efficient classifier, is used to realize this model. It exploits the statistical nature (endmember spectral variability) of the extracted endmember representatives from the hyperspectral scene, rather than solving the problem according to the ideal model in which only the mean spectra of each training sample set is used. Several experiments are carried out on simulated and real hyperspectral images. The obtained results validate the high performance of the proposed technique in abundance quantification which is a key subpixel information detection capability. © 2006 IEEE.


Yue X.,Harbin Institute of Technology | Dai Z.,Peking University
Advances in Colloid and Interface Science | Year: 2014

Liposomes have been extensively investigated as possible carriers for diagnostic or therapeutic agents due to their unique properties. However, liposomes still have not attained their full potential as drug and gene delivery vehicles because of their insufficient morphological stability. Recently, a super-stable and freestanding hybrid liposomal cerasome (partially ceramic- or silica-coated liposome) has drawn much attention as a novel drug delivery system because its atomic layer of polyorganosiloxane surface imparts higher morphological stability than conventional liposomes and its liposomal bilayer structure reduces the overall rigidity and density greatly compared to silica nanoparticles. Cerasomes are more biocompatible than silica nanoparticles due to the incorporation of the liposomal architecture into cerasomes. Cerasomes combine the advantages of both liposomes and silica nanoparticles but overcome their disadvantages so cerasomes are ideal drug delivery systems. The present review will first highlights some of the key advances of the past decade in the technology of cerasome production and then review current biomedical applications of cerasomes, with a view to stimulating further research in this area of study. © 2013 Elsevier B.V.


Liu M.,Harbin Institute of Technology | Cao X.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide
IEEE Transactions on Fuzzy Systems | Year: 2013

This paper addresses the problem of fault estimation and fault-tolerant control for a class of Takagi-Sugeno (T-S) fuzzy Itô stochastic systems subject to simultaneously sensor and actuator faults. The main difficulty in this study is that sensor faults, actuator faults, and stochastic noise that are governed by Brownian motion are taken into simultaneous consideration in a unified framework, and traditional fault-tolerant approaches are not effective to solve this research issue. A new descriptor fuzzy sliding-mode observer approach is presented in this paper to obtain the simultaneous estimates of system state, sensor fault, and actuator fault vectors. Based on the state estimates, an observer-based fault-tolerant control (FTC) scheme is developed to stabilize the resulting closed-loop system. Finally, a simulation example is provided to show the effectiveness of the proposed fault-tolerant approach. © 1993-2012 IEEE.


Su X.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2013

This paper focuses on analyzing a new model transformation of discrete-time Takagi-Sugeno (T-S) fuzzy systems with time-varying delays and applying it to dynamic output feedback (DOF) controller design. A new comparison model is proposed by employing a new approximation for time-varying delay state, and then, a delay partitioning method is used to analyze the scaled small gain of this comparison model. A sufficient condition on discrete-time T-S fuzzy systems with time-varying delays, which guarantees the corresponding closed-loop system to be asymptotically stable and has an induced ℓ2 disturbance attenuation performance, is derived by employing the scaled small-gain theorem. Then, the solvability condition for the induced ℓ2 DOF control is also established, by which the DOF controller can be solved as linear matrix inequality optimization problems. Finally, examples are provided to illustrate the effectiveness of the proposed approaches. © 1993-2012 IEEE.


Xie J.,Texas Tech University | Otto R.,University of California at San Diego | Mikosch J.,Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy | Zhang J.,Harbin Institute of Technology | And 2 more authors.
Accounts of Chemical Research | Year: 2014

ConspectusFor the traditional model of gas-phase X- + CH3Y SN2 reactions, C3v ion-dipole pre- and postreaction complexes X- - -CH3Y and XCH3 - -Y-, separated by a central barrier, are formed. Statistical intramolecular dynamics are assumed for these complexes, so that their unimolecular rate constants are given by RRKM theory. Both previous simulations and experiments have shown that the dynamics of these complexes are not statistical and of interest is how these nonstatistical dynamics affect the SN2 rate constant. This work also found there was a transition from an indirect, nonstatistical, complex forming mechanism, to a direct mechanism, as either the vibrational and/or relative translational energy of the reactants was increased. The current Account reviews recent collaborative studies involving molecular beam ion-imaging experiments and direct (on-the-fly) dynamics simulations of the SN2 reactions for which Cl-, F-, and OH- react with CH3I. Also considered are reactions of the microsolvated anions OH-(H2O) and OH-(H2O)2 with CH3I. These studies have provided a detailed understanding of the atomistic mechanisms for these SN2 reactions.Overall, the atomistic dynamics for the Cl- + CH3I SN2 reaction follows those found in previous studies. The reaction is indirect, complex forming at low reactant collision energies, and then there is a transition to direct reaction between 0.2 and 0.4 eV. The direct reaction may occur by rebound mechanism, in which the ClCH3 product rebounds backward from the I- product or a stripping mechanism in which Cl- strips CH3 from the I atom and scatters in the forward direction. A similar indirect to direct mechanistic transition was observed in previous work for the Cl- + CH3Cl and Cl- + CH3Br SN2 reactions. At the high collision energy of 1.9 eV, a new indirect mechanism, called the roundabout, was discovered.For the F- + CH3I reaction, there is not a transition from indirect to direct reaction as Erel is increased. The indirect mechanism, with prereaction complex formation, is important at all the Erel investigated, contributing up ∼60% of the reaction. The remaining direct reaction occurs by the rebound and stripping mechanisms.Though the potential energy curve for the OH- + CH3I reaction is similar to that for F- + CH3I, the two reactions have different dynamics. They are akin, in that for both there is not a transition from an indirect to direct reaction. However, for F- + CH3I indirect reaction dominates at all Erel, but it is less important for OH- + CH3I and becomes negligible as Erel is increased. Stripping is a minor channel for F- + CH3I, but accounts for more than 60% of the OH- + CH3I reaction at high Erel.Adding one or two H2O molecules to OH- alters the reaction dynamics from that for unsolvated OH-. Adding one H2O molecule enhances indirect reaction at low Erel, and changes the reaction mechanism from primarily stripping to rebound at high Erel. With two H2O molecules the dynamics is indirect and isotropic at all collision energies. © 2014 American Chemical Society.


Yun Y.,University of Macau | Li Y.,Harbin Institute of Technology
Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME | Year: 2012

In recent years, many applications in precision engineering require a careful isolation of the instrument from the vibration sources by adopting active vibration isolation system to achieve a very low remaining vibration level, especially for the very low frequency under 10 Hz vibration signals. This paper presents a 3-PUPU dual parallel manipulator for both rough positioning and active vibration isolation in a wide-range workspace based on our previous research experiences in the systematical modeling and study of parallel robots. The manipulator is designed as a kind of macromicro hybrid robot. Both the kinematics model for macro motion and dynamics model for micro motion are established by using stiffness equation and the Kane's method, respectively. An active vibration control strategy is described by using the H 2 method. Moreover, numerical simulations on the inverse solution for macro motion, workspace, and the active vibration control effects are performed at the end of this paper. © 2012 American Society of Mechanical Engineers.


Li F.,Harbin Institute of Technology | Li F.,University of Adelaide | Wu L.,Harbin Institute of Technology | Shi P.,University of Adelaide | And 2 more authors.
Automatica | Year: 2015

This paper is concerned with the state estimation and sliding mode control problems for phase-type semi-Markovian jump systems. Using a supplementary variable technique and a plant transformation, a finite phase-type semi-Markov process has been transformed into a finite Markov chain, which is called its associated Markov chain. As a result, phase-type semi-Markovian jump systems can be equivalently expressed as its associated Markovian jump systems. A sliding surface is then constructed and a sliding mode controller is synthesized to ensure that the associated Markovian jump systems satisfy the reaching condition. Moreover, an observer-based sliding mode control problem is investigated. Sufficient conditions are established for the solvability of the desired observer. Two numerical examples are presented to show the effectiveness of the proposed design techniques. © 2014 Elsevier Ltd. All rights reserved.


Zhou J.,Harbin Institute of Technology | Hu Q.,Harbin Institute of Technology | Friswell M.I.,University of Swansea
Journal of Guidance, Control, and Dynamics | Year: 2013

This paper investigates a quaternion-based finite time attitude synchronization and stabilization problem for satellite formation flying. Sufficient conditions are presented for finite time boundness and stability of this distributed consensus problem. More specifically, a nonlinear control law based on a finite time control technique is developed such that the attitude of the rigid spacecraft will coordinate and converge to the attitude of the leader, while the angular velocity will converge to zero in finite time. The associated stability proof is constructive and accomplished by adding a power integrator term in the Lyapunov function. Furthermore, to reduce the heavy communication burden, a modified control law is then designed by introducing a finite time sliding-mode estimator such that only one satellite has to communicate with the leader. Simulation results are presented to demonstrate the effectiveness of the designed scheme, especially the potential advantages derived through the inclusion of the continuous finite time control method, such as the fast convergent rate and the alleviation of chattering. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


Mei J.,Harbin Institute of Technology | Ren W.,University of California at Riverside | Ma G.,Harbin Institute of Technology
Automatica | Year: 2013

In this paper, we study the distributed coordination for second-order multi-agent systems with intrinsic nonlinear dynamics under an undirected graph that characterizes the interaction among the agents or followers. Both the leaderless consensus problem and the coordinated tracking problem with a dynamic leader are considered. By introducing a distributed filter for each agent or follower, the proposed control algorithms use only relative position measurements in the absence of communication. In the special case without the intrinsic nonlinear dynamics, i.e., for multi-agent systems with double-integrator dynamics, we further derive a necessary and sufficient condition for the leaderless consensus problem under a general directed graph. Finally, simulation examples are provided to show the effectiveness of the proposed control algorithms. © 2013 Elsevier Ltd. All rights reserved.


Lv G.,Henan University | Pang P.Y.H.,National University of Singapore | Wang M.,Harbin Institute of Technology
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2013

This paper is concerned with the non-uniform dependence on initial data for the μ-b equation on the circle. Using the approximate solution method, we construct two solution sequences to show that the data-to-solution map of the Cauchy problem of the μ-b equation is not uniformly continuous in Hs(S). © 2013 Springer Basel.


Zhang Q.,University of California at Riverside | Li N.,University of California at Riverside | Li N.,Harbin Institute of Technology | Goebl J.,University of California at Riverside | And 2 more authors.
Journal of the American Chemical Society | Year: 2011

In this work we have carried out systematic studies and identified the critical role of hydrogen peroxide instead of the generally believed citrate in the well-known chemical reduction route to silver nanoplates. This improved understanding allows us to develop consistently reproducible processes for the synthesis of nanoplates with high efficiency and yields. By harnessing the oxidative power of H2O2, various silver sources including silver salts and metallic silver can be directly converted to nanoplates with the assistance of an appropriate capping ligand, thus significantly enhancing the reproducibility of the synthesis. Contrary to the previous conclusion that citrate is the key component, we have determined that the group of ligands with selective adhesion to Ag (111) facets can be expanded to many di-and tricarboxylate compounds whose two nearest carboxylate groups are separated by two or three carbon atoms. We have also found that the widely used secondary ligand polyvinylpyrrolidone can be replaced by many hydroxyl group-containing compounds or even removed entirely while still producing nanoplates of excellent uniformity and stability. In addition to the general understanding of NaBH 4 as a reducing agent, it has also been found to act as a capping agent to stabilize the silver nanoparticles, prolong the initiation time required for nanoplate nucleation, and contribute to the control of the thickness as well as the aspect ratio of silver nanoplates. The improved insight into the specific roles of the reaction components and significantly enhanced reproducibility are expected to help elucidate the formation mechanism of this interesting nanostructure. © 2011 American Chemical Society.


Yang W.,Harbin Institute of Technology | Liu M.,Harbin Institute of Technology | Shi P.,Heilongjiang Communications Polytechnic Qiqihar
Signal Processing | Year: 2012

This paper is concerned with the H∞ filtering problem for a class of nonlinear stochastic systems subject to sensor saturation over unreliable communication channel. The investigated plant is described by a class of stochastic systems with global Lipschitz nonlinearities and random noise depending on state and external-disturbance. The characteristic of sensor saturation is handled by a decomposition approach which is more general than those in the existing work where the sensor saturation and network-induced phenomenon were considered separately. The communication links between the plant and filter are unreliable network channels, and the effects of output logarithmic quantization and data packet losses are considered together. The purpose of this work is to design a full-order filter by employing the incomplete output measurements such that the dynamics of the estimation error is guaranteed to be stochastically stable. Both filter analysis and synthesis problems are investigated, and the explicit expression of the desired filters is also provided. Finally, a numerical simulation is illustrated to show the effectiveness of the designing filtering technique. © 2011 Elsevier B.V.


Wang J.,Harbin Institute of Technology | Wu S.,National University of Singapore | Gao H.,Harbin Institute of Technology | Li J.,Harbin Institute of Technology | Ooi B.C.,National University of Singapore
Proceedings of the ACM SIGMOD International Conference on Management of Data | Year: 2010

Providing scalable database services is an essential requirement for extending many existing applications of the Cloud platform. Due to the diversity of applications, database services on the Cloud must support large-scale data analytical jobs and high concurrent OLTP queries. Most existing work focuses on some specific type of applications. To provide an integrated framework, we are designing a new system, epiC, as our solution to next-generation database systems. In epiC, indexes play an important role in improving overall performance. Different types of indexes are built to provide efficient query processing for different applications. In this paper, we propose RT-CAN, a multi-dimensional indexing scheme in epiC. RT-CAN integrates CAN [23] based routing protocol and the R-tree based indexing scheme to support efficient multi-dimensional query processing in a Cloud system. RT-CAN organizes storage and compute nodes into an overlay structure based on an extended CAN protocol. In our proposal, we make a simple assumption that each compute node uses an R-tree like indexing structure to index the data that are locally stored. We propose a query-conscious cost model that selects beneficial local R-tree nodes for publishing. By keeping the number of persistently connected nodes small and maintaining a global multi-dimensional search index, we can locate the compute nodes that may contain the answer with a few hops, making the scheme scalable in terms of data volume and number of compute nodes. Experiments on Amazon's EC2 show that our proposed routing protocol and indexing scheme are robust, efficient and scalable. Copyright 2010 ACM.


Chen L.,Nanyang Technological University | Gu Y.,Nanyang Technological University | Cao C.,National University of Singapore | Zhang J.,Harbin Institute of Technology | And 2 more authors.
Water Research | Year: 2014

A submerged anaerobic membrane bioreactor with forward osmosis membrane (FO-AnMBR) was operated at 25°C for the treatment of synthetic wastewater. As the experiment progressed, the water flux reduced due to the membrane fouling and the increasing salinity in the reactor, and achieved at around 3.5 LMH in one cycle. It was worth noting that the level of salinity in the reactor was not a concern in terms of inhibition or toxic effects on the biological processes. The FO-AnMBR process exhibited greater than 96% removal of organic carbon, nearly 100% of total phosphorus and 62% of ammonia-nitrogen, respectively, suggesting a better removal efficiency than the conventional anaerobic membrane bioreactor. The methane and carbon dioxide compositions achieved concentrations of around 65%-78% and 22%-35%, respectively; and no obvious difference in the biogas composition was observed with the changes of conductivity. With respect to the methane yield, an average value of 0.21LCH4g-1COD was obtained, exhibiting the feasibility of energy recovery by this FO-AnMBR system. Additionally, an increase in the salinity enhanced the accumulation of soluble microbial products, especially for the proteins with 88.9% increment as the conductivity increased from 1.2 to 17.3mscm-1. In contrast, a relatively stable concentration of extracellular polymer substances (EPS) was observed, indicating that the influence of conductivity on EPS cannot be directly correlated. © 2013 Elsevier Ltd.


The trapping of photons in low-refraction-index materials is thought to be difficult in conventional photonic structures that employ total internal reflection. Specifically, the whispering gallery mode (WGM) microcavity, which is an important optical component, has to rely on a refraction index with high contrast to the surrounding environment to manifest excellent light confinement. A team led by Professor Yun-Feng Xiao at Peking University collaborated with researchers from the Harbin Institute of Technology, and demonstrated that an optical microcavity structure consisting of a low-refraction-index silica microtoroid that was directly bonded on a high-refraction-index silicon substrate supports high-Q fundamental WGMs. This work has been published in a recent issue of Optica.


News Article | November 11, 2015
Site: www.rdmag.com

A new, onion-like nanoparticle could open new frontiers in biomaging, solar energy harvesting and light-based security techniques. The particle's innovation lies in its layers: a coating of organic dye, a neodymium-containing shell, and a core that incorporates ytterbium and thulium. Together, these strata convert invisible near-infrared light to higher energy blue and UV light with record-high efficiency, a trick that could improve the performance of technologies ranging from deep-tissue imaging and light-induced therapy to security inks used for printing money. When it comes to bioimaging, near-infrared light could be used to activate the light-emitting nanoparticles deep inside the body, providing high-contrast images of areas of interest. In the realm of security, nanoparticle-infused inks could be incorporated into currency designs; such ink would be invisible to the naked eye, but glow blue when hit by a low-energy laser pulse -- a trait very difficult for counterfeiters to reproduce. "It opens up multiple possibilities for the future," says Tymish Ohulchanskyy, deputy director of photomedicine and research associate professor at the Institute for Lasers, Photonics, and Biophotonics (ILPB) at the Univ. at Buffalo. "By creating special layers that help transfer energy efficiently from the surface of the particle to the core, which emits blue and UV light, our design helps overcome some of the long-standing obstacles that previous technologies faced," says Guanying Chen, professor of chemistry at Harbin Institute of Technology and ILPB research associate professor. "Our particle is about 100 times more efficient at 'upconverting' light than similar nanoparticles created in the past, making it much more practical," says Jossana Damasco, a UB chemistry PhD student who played a key role in the project. The research was published online in Nano Letters on Oct. 21 and led by the Institute for Lasers, Photonics, and Biophotonics at UB, and the Harbin Institute of Technology in China, with contributions from the Royal Institute of Technology in Sweden; Tomsk State University in Russia; and the University of Massachusetts Medical School. The study's senior author was Paras Prasad, ILPB executive director and SUNY Distinguished Professor in chemistry, physics, medicine and electrical engineering at UB. Converting low-energy light to light of higher energies isn't easy to do. The process involves capturing two or more tiny packets of light called "photons" from a low-energy light source, and combining their energy to form a single, higher-energy photon. The onionesque nanoparticle performs this task beautifully. Each of its three layers fulfills a unique function: So why not just use the core? Why add the dye and neodymium layer at all? As Ohulchanskyy and Chen explain, the core itself is inefficient in absorbing photons from the outside world. That's where the dye comes in. Once you add the dye, the neodymium-containing layer is necessary for transferring energy efficiently from dye to core. Ohulchanskyy uses the analogy of a staircase to explain why this is: When molecules or ions in a material absorb a photon, they enter an "excited" state from which they can transfer energy to other molecules or ions. The most efficient transfer occurs between molecules or ions whose excited states require a similar amount of energy to obtain, but the dye and ytterbium ions have excited states with very different energies. So the team added neodymium -- whose excited state is in between that of the dye and thulium's -- to act as a bridge between the two, creating a "staircase" for the energy to travel down to reach emitting thulium ions.


News Article | November 10, 2015
Site: phys.org

The particle's innovation lies in its layers: a coating of organic dye, a neodymium-containing shell, and a core that incorporates ytterbium and thulium. Together, these strata convert invisible near-infrared light to higher energy blue and UV light with record-high efficiency, a trick that could improve the performance of technologies ranging from deep-tissue imaging and light-induced therapy to security inks used for printing money. When it comes to bioimaging, near-infrared light could be used to activate the light-emitting nanoparticles deep inside the body, providing high-contrast images of areas of interest. In the realm of security, nanoparticle-infused inks could be incorporated into currency designs; such ink would be invisible to the naked eye, but glow blue when hit by a low-energy laser pulse—a trait very difficult for counterfeiters to reproduce. "It opens up multiple possibilities for the future," says Tymish Ohulchanskyy, deputy director of photomedicine and research associate professor at the Institute for Lasers, Photonics, and Biophotonics (ILPB) at the University at Buffalo. "By creating special layers that help transfer energy efficiently from the surface of the particle to the core, which emits blue and UV light, our design helps overcome some of the long-standing obstacles that previous technologies faced," says Guanying Chen, professor of chemistry at Harbin Institute of Technology and ILPB research associate professor. "Our particle is about 100 times more efficient at 'upconverting' light than similar nanoparticles created in the past, making it much more practical," says Jossana Damasco, a UB chemistry PhD student who played a key role in the project. The research was published online in Nano Letters on Oct. 21 and led by the Institute for Lasers, Photonics, and Biophotonics at UB, and the Harbin Institute of Technology in China, with contributions from the Royal Institute of Technology in Sweden; Tomsk State University in Russia; and the University of Massachusetts Medical School. The study's senior author was Paras Prasad, ILPB executive director and SUNY Distinguished Professor in chemistry, physics, medicine and electrical engineering at UB. Converting low-energy light to light of higher energies isn't easy to do. The process involves capturing two or more tiny packets of light called "photons" from a low-energy light source, and combining their energy to form a single, higher-energy photon. The onionesque nanoparticle performs this task beautifully. Each of its three layers fulfills a unique function: So why not just use the core? Why add the dye and neodymium layer at all? As Ohulchanskyy and Chen explain, the core itself is inefficient in absorbing photons from the outside world. That's where the dye comes in. Once you add the dye, the neodymium-containing layer is necessary for transferring energy efficiently from dye to core. Ohulchanskyy uses the analogy of a staircase to explain why this is: When molecules or ions in a material absorb a photon, they enter an "excited" state from which they can transfer energy to other molecules or ions. The most efficient transfer occurs between molecules or ions whose excited states require a similar amount of energy to obtain, but the dye and ytterbium ions have excited states with very different energies. So the team added neodymium—whose excited state is in between that of the dye and thulium's—to act as a bridge between the two, creating a "staircase" for the energy to travel down to reach emitting thulium ions. Explore further: Nanoparticles glow through thick layer of tissue


News Article | November 11, 2015
Site: www.cemag.us

A new, onion-like nanoparticle could open new frontiers in biomaging, solar energy harvesting, and light-based security techniques. The particle’s innovation lies in its layers: a coating of organic dye, a neodymium-containing shell, and a core that incorporates ytterbium and thulium. Together, these strata convert invisible near-infrared light to higher energy blue and UV light with record-high efficiency, a trick that could improve the performance of technologies ranging from deep-tissue imaging and light-induced therapy to security inks used for printing money. When it comes to bioimaging, near-infrared light could be used to activate the light-emitting nanoparticles deep inside the body, providing high-contrast images of areas of interest. In the realm of security, nanoparticle-infused inks could be incorporated into currency designs; such ink would be invisible to the naked eye, but glow blue when hit by a low-energy laser pulse — a trait very difficult for counterfeiters to reproduce. “It opens up multiple possibilities for the future,” says Tymish Ohulchanskyy, deputy director of photomedicine and research associate professor at the Institute for Lasers, Photonics, and Biophotonics (ILPB) at the University at Buffalo. “By creating special layers that help transfer energy efficiently from the surface of the particle to the core, which emits blue and UV light, our design helps overcome some of the long-standing obstacles that previous technologies faced,” says Guanying Chen, professor of chemistry at Harbin Institute of Technology and ILPB research associate professor. “Our particle is about 100 times more efficient at ‘upconverting’ light than similar nanoparticles created in the past, making it much more practical,” says Jossana Damasco, a UB chemistry PhD student who played a key role in the project. The research was published online in Nano Letters and led by the Institute for Lasers, Photonics, and Biophotonics at UB, and the Harbin Institute of Technology in China, with contributions from the Royal Institute of Technology in Sweden; Tomsk State University in Russia; and the University of Massachusetts Medical School. The study’s senior author was Paras Prasad, ILPB executive director and SUNY Distinguished Professor in chemistry, physics, medicine and electrical engineering at UB. Converting low-energy light to light of higher energies isn’t easy to do. The process involves capturing two or more tiny packets of light called “photons” from a low-energy light source, and combining their energy to form a single, higher-energy photon. The onionesque nanoparticle performs this task beautifully. Each of its three layers fulfills a unique function: The outermost layer is a coating of organic dye. This dye is adept at absorbing photons from low-energy near-infrared light sources. It acts as an “antenna” for the nanoparticle, harvesting light and transferring energy inside, Ohulchanskyy says. The next layer is a neodymium-containing shell. This layer acts as a bridge, transferring energy from the dye to the particle’s light-emitting core. Inside the light-emitting core, ytterbium and thulium ions work in concert. The ytterbium ions draw energy into the core and pass the energy on to the thulium ions, which have special properties that enable them to absorb the energy of three, four or five photons at once, and then emit a single higher-energy photon of blue and UV light. So why not just use the core? Why add the dye and neodymium layer at all? As Ohulchanskyy and Chen explain, the core itself is inefficient in absorbing photons from the outside world. That’s where the dye comes in. Once you add the dye, the neodymium-containing layer is necessary for transferring energy efficiently from dye to core. Ohulchanskyy uses the analogy of a staircase to explain why this is: When molecules or ions in a material absorb a photon, they enter an “excited” state from which they can transfer energy to other molecules or ions. The most efficient transfer occurs between molecules or ions whose excited states require a similar amount of energy to obtain, but the dye and ytterbium ions have excited states with very different energies. So the team added neodymium — whose excited state is in between that of the dye and thulium’s — to act as a bridge between the two, creating a “staircase” for the energy to travel down to reach emitting thulium ions. The research was funded by the Air Force Office of Scientific Research, the National Science Fund for Distinguished Young Scholars, the International Cooperation Project in the Ministry of Science and Technology in China, the Program for Basic Research Excellent Talents in Harbin Institute of Technology, and the Fundamental Research Funds for the Central Universities in China. In addition to Chen, Damasco, Ohulchanskyy and Prasad, co-authors on the paper included Hailong Qiu, Wei Shao, Rashid R. Valiev, Xiang Wu, Gang Han, Yan Wang, Chunhui Yang, and Hans Agren.


Home > Press > Onion-like layers help this efficient new nanoparticle glow: A dye-coated surface is 1 of 3 specially crafted layers that help the particle emit light ideal for bioimaging Abstract: A new, onion-like nanoparticle could open new frontiers in biomaging, solar energy harvesting and light-based security techniques. The particle's innovation lies in its layers: a coating of organic dye, a neodymium-containing shell, and a core that incorporates ytterbium and thulium. Together, these strata convert invisible near-infrared light to higher energy blue and UV light with record-high efficiency, a trick that could improve the performance of technologies ranging from deep-tissue imaging and light-induced therapy to security inks used for printing money. When it comes to bioimaging, near-infrared light could be used to activate the light-emitting nanoparticles deep inside the body, providing high-contrast images of areas of interest. In the realm of security, nanoparticle-infused inks could be incorporated into currency designs; such ink would be invisible to the naked eye, but glow blue when hit by a low-energy laser pulse -- a trait very difficult for counterfeiters to reproduce. "It opens up multiple possibilities for the future," says Tymish Ohulchanskyy, deputy director of photomedicine and research associate professor at the Institute for Lasers, Photonics, and Biophotonics (ILPB) at the University at Buffalo. "By creating special layers that help transfer energy efficiently from the surface of the particle to the core, which emits blue and UV light, our design helps overcome some of the long-standing obstacles that previous technologies faced," says Guanying Chen, professor of chemistry at Harbin Institute of Technology and ILPB research associate professor. "Our particle is about 100 times more efficient at 'upconverting' light than similar nanoparticles created in the past, making it much more practical," says Jossana Damasco, a UB chemistry PhD student who played a key role in the project. The research was published online in Nano Letters on Oct. 21 and led by the Institute for Lasers, Photonics, and Biophotonics at UB, and the Harbin Institute of Technology in China, with contributions from the Royal Institute of Technology in Sweden; Tomsk State University in Russia; and the University of Massachusetts Medical School. The study's senior author was Paras Prasad, ILPB executive director and SUNY Distinguished Professor in chemistry, physics, medicine and electrical engineering at UB. Peeling back the layers Converting low-energy light to light of higher energies isn't easy to do. The process involves capturing two or more tiny packets of light called "photons" from a low-energy light source, and combining their energy to form a single, higher-energy photon. The onionesque nanoparticle performs this task beautifully. Each of its three layers fulfills a unique function: The outermost layer is a coating of organic dye. This dye is adept at absorbing photons from low-energy near-infrared light sources. It acts as an "antenna" for the nanoparticle, harvesting light and transferring energy inside, Ohulchanskyy says. The next layer is a neodymium-containing shell. This layer acts as a bridge, transferring energy from the dye to the particle's light-emitting core. Inside the light-emitting core, ytterbium and thulium ions work in concert. The ytterbium ions draw energy into the core and pass the energy on to the thulium ions, which have special properties that enable them to absorb the energy of three, four or five photons at once, and then emit a single higher-energy photon of blue and UV light. So why not just use the core? Why add the dye and neodymium layer at all? As Ohulchanskyy and Chen explain, the core itself is inefficient in absorbing photons from the outside world. That's where the dye comes in. Once you add the dye, the neodymium-containing layer is necessary for transferring energy efficiently from dye to core. Ohulchanskyy uses the analogy of a staircase to explain why this is: When molecules or ions in a material absorb a photon, they enter an "excited" state from which they can transfer energy to other molecules or ions. The most efficient transfer occurs between molecules or ions whose excited states require a similar amount of energy to obtain, but the dye and ytterbium ions have excited states with very different energies. So the team added neodymium -- whose excited state is in between that of the dye and thulium's -- to act as a bridge between the two, creating a "staircase" for the energy to travel down to reach emitting thulium ions. ### The research was funded by the Air Force Office of Scientific Research, the National Science Fund for Distinguished Young Scholars, the International Cooperation Project in the Ministry of Science and Technology in China, the Program for Basic Research Excellent Talents in Harbin Institute of Technology, and the Fundamental Research Funds for the Central Universities in China. In addition to Chen, Damasco, Ohulchanskyy and Prasad, co-authors on the paper included Hailong Qiu, Wei Shao, Rashid R. Valiev, Xiang Wu, Gang Han, Yan Wang, Chunhui Yang and Hans Agren. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Zhang S.,Harbin Institute of Technology | Zhang S.,Pacific Northwest National Laboratory | Shao Y.,Pacific Northwest National Laboratory | Yin G.,Harbin Institute of Technology | Lin Y.,Pacific Northwest National Laboratory
Angewandte Chemie - International Edition | Year: 2010

"Chemical Equation Presented" Opposites attract: A Pt-around-Au nanocomposite is synthesized by electrostatic self-assembly (see picture; PDDA = poly (diallyldimethylammonium chloride)). This catalyst shows significantly improved activity towards formic acid oxidation versus pure Pt catalysts. The possible reason is the efficient spillover of HCOO from Au to the surrounding Pt nanoparticles, where HCOO is further oxidized to CO2. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.


Xu W.,Pacific Northwest National Laboratory | Wang J.,Pacific Northwest National Laboratory | Wang J.,Shanghai JiaoTong University | Ding F.,Tianjin Institute of Power Sources | And 5 more authors.
Energy and Environmental Science | Year: 2014

Lithium (Li) metal is an ideal anode material for rechargeable batteries due to its extremely high theoretical specific capacity (3860 mA h g -1), low density (0.59 g cm-3) and the lowest negative electrochemical potential (-3.040 V vs. the standard hydrogen electrode). Unfortunately, uncontrollable dendritic Li growth and limited Coulombic efficiency during Li deposition/stripping inherent in these batteries have prevented their practical applications over the past 40 years. With the emergence of post-Li-ion batteries, safe and efficient operation of Li metal anodes has become an enabling technology which may determine the fate of several promising candidates for the next generation energy storage systems, including rechargeable Li-air batteries, Li-S batteries, and Li metal batteries which utilize intercalation compounds as cathodes. In this paper, various factors that affect the morphology and Coulombic efficiency of Li metal anodes have been analyzed. Technologies utilized to characterize the morphology of Li deposition and the results obtained by modelling of Li dendrite growth have also been reviewed. Finally, recent development and urgent need in this field are discussed. © The Royal Society of Chemistry.


Wu L.,Harbin Institute of Technology | Yang X.,Harbin Institute of Technology | Lam H.-K.,King's College London
IEEE Transactions on Fuzzy Systems | Year: 2014

This paper is concerned with the problems of dissipativity analysis and synthesis for discrete-time Takagi-Sugeno fuzzy systems with stochastic perturbation and time-varying delay. First, a novel model transformation method is introduced to pull the time-varying delay uncertainty out of the original system. Consequently, the transformed model is composed of a linear time-invariant system and a norm-bounded uncertain subsystem. By using this model transformation method combined with the Lyapunov-Krasovskii technique, sufficient conditions of the dissipativity are established. Then, a fuzzy controller is designed to guarantee the dissipative performance of the closed-loop system. Finally, three examples are presented: one shows the effectiveness of model transformation method, the second performs the comparison with alternative approaches, and the third illustrates the applicability of the proposed dissipative control methods. © 1993-2012 IEEE.


Yao T.,Harbin Institute of Technology | Cui T.,Harbin Institute of Technology | Fang X.,Harbin Institute of Technology | Cui F.,Harbin Institute of Technology | Wu J.,Heilongjiang University
Nanoscale | Year: 2013

Yolk-shell composites with a movable FexOy core and mesoporous SiO2 (mSiO2) shell, together with Pd nanoparticles uniformly anchoring on the inner surface, were prepared. The structure and composition of as-prepared catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller measurement and Fourier-transform infrared spectroscopy, respectively. They are ideal candidates as nanoreactors for heterogeneous catalysis due to their special structure. The catalytic performance of FexO y/Pd@mSiO2 composites was studied by the reduction of 4-nitrophenol with NaBH4 as a reducing agent. Their reaction rate constant was calculated according to the pseudo-first-order reaction equation. The catalysts could be easily recycled by an external magnetic field due to their superparamagnetic property. Besides good catalytic property, another merit of FexOy/Pd@mSiO2 composites was high stability. We have compared the stability between FexO y/Pd@mSiO2 and Fe3O4@C/Pd composites by ultrasonic treatment and HNO3 solution etching, the stability of the former was much better than the later. © 2013 The Royal Society of Chemistry.


Wu L.,Harbin Institute of Technology | Wu L.,Imperial College London | Yang X.,Bohai University | Li F.,Heilongjiang University
IEEE/ASME Transactions on Mechatronics | Year: 2013

This paper presents a novel nonfragile output tracking control scheme for flexible hypersonic air-breathing vehicles (HAVs). This problem is challenging due to the complex interactions between the aerodynamics, the propulsion system, and the structural dynamics. By utilizing the curve-fit and the least-squares methods, a new model for HAVs is established, and then converted into a linear parameter-varying system, in which the scheduling variables depend on a handful of meaningful states and parameters. With a specified reference model, a tracking error model is also proposed. The nonfragile output tracking controller is designed, which guarantees the tracking error dynamics to be robustly stable. Finally, simulation results are presented to show the effectiveness of the proposed control design scheme. © 1996-2012 IEEE.


Lo S.S.,University of Notre Dame | Shi H.Y.,University of Notre Dame | Shi H.Y.,Harbin Institute of Technology | Huang L.,University of Notre Dame | Hartland G.V.,University of Notre Dame
Optics Letters | Year: 2013

Knowledge of how energy and charge carriers move in nanoscale systems is essential for engineering efficient devices. In this Letter, we demonstrate a technique to directly image dynamics in nanostructures based on laser scanning transient absorption microscopy, which provides near diffraction-limited spatial resolution and ultrafast time resolution. The capabilities of the technique are demonstrated by experiments on propagating surface plasmon polariton modes of Au nanowires, although these measurements can be used to study a variety of fluorescent and nonfluorescent systems. © 2013 Optical Society of America.


Gao B.,University of Notre Dame | Gao B.,Harbin Institute of Technology | Hartland G.V.,University of Notre Dame | Huang L.,University of Notre Dame
Journal of Physical Chemistry Letters | Year: 2013

We present femtosecond transient absorption measurements of individual metallic single-wall carbon nanotubes (SWNTs) to elucidate environmental effects on their spectroscopy and dynamics. Isolated suspended SWNTs were located using atomic force microscopy, and Raman spectroscopy was employed to determine the chiral index of select nanotubes. Transient absorption spectra of the SWNTs were obtained by recording transient absorption images at different probe wavelengths. This unique experimental approach removes sample heterogeneity in ultrafast measurements of these complex materials and provides a direct means to unravel the role of the substrate. The results show a ∼40 meV red shift of the lowest exciton transition, which is attributed to dielectric screening effects by the substrate. Energy relaxation in individual metallic nanotubes was observed with decay constants of a few hundred fs and about 10 ps. We attributed the fast and slow decay components to carrier scattering by optical and acoustic phonons, respectively. © 2013 American Chemical Society.


Shi H.,University of Notre Dame | Shi H.,Harbin Institute of Technology | Yan R.,University of Notre Dame | Bertolazzi S.,Ecole Polytechnique Federale de Lausanne | And 6 more authors.
ACS Nano | Year: 2013

Femtosecond transient absorption spectroscopy and microscopy were employed to study exciton dynamics in suspended and Si3N4 substrate-supported monolayer and few-layer MoS2 2D crystals. Exciton dynamics for the monolayer and few-layer structures were found to be remarkably different from those of thick crystals when probed at energies near that of the lowest energy direct exciton (A exciton). The intraband relaxation rate was enhanced by more than 40 fold in the monolayer in comparison to that observed in the thick crystals, which we attributed to defect assisted scattering. Faster electron-hole recombination was found in monolayer and few-layer structures due to quantum confinement effects that lead to an indirect-direct band gap crossover. Nonradiative rather than radiative relaxation pathways dominate the dynamics in the monolayer and few-layer MoS2. Fast trapping of excitons by surface trap states was observed in monolayer and few-layer structures, pointing to the importance of controlling surface properties in atomically thin crystals such as MoS2 along with controlling their dimensions. © 2012 American Chemical Society.


Chen G.,State University of New York at Buffalo | Chen G.,Harbin Institute of Technology | Agren H.,KTH Royal Institute of Technology | Ohulchanskyy T.Y.,State University of New York at Buffalo | And 2 more authors.
Chemical Society Reviews | Year: 2015

Light upconverting nanostructures employing lanthanide ions constitute an emerging research field recognized with wide ramifications and impact in many areas ranging from healthcare, to energy and, to security. The core-shell design of these nanostructures allows us to deliberately introduce a hierarchy of electronic energy states, thus providing unprecedented opportunities to manipulate the electronic excitation, energy transfer and upconverted emissions. The core-shell morphology also causes the suppression of quenching mechanisms to produce efficient upconversion emission for biophotonic and photonic applications. Using hierarchical architect, whereby each shell layer can be defined to have a specific feature, the electronic structure as well as the physiochemical structure of the upconverting nanomaterials can be tuned to couple other electronic states on the surface such as excitations of organic dye molecules or localized surface plasmons from metallic nanostructures, or to introduce a broad range of imaging or therapeutic modalities into a single conduct. In this review, we summarize the key aspects of nanophotonic control of the light upconverting nanoparticles through governed design and preparation of hierarchical shells in the core-shell nanostructures, and review their emerging applications in the biomedical field, solar energy conversion, as well as security encoding. This journal is © The Royal Society of Chemistry.


Zhang S.,Harbin Institute of Technology | Shao Y.,Pacific Northwest National Laboratory | Yin G.,Harbin Institute of Technology | Lin Y.,Pacific Northwest National Laboratory
Journal of Materials Chemistry A | Year: 2013

Polymer electrolyte membrane (PEM) fuel cells are attracting much attention as promising clean power sources and an alternative to conventional internal combustion engines, secondary batteries, and other power sources. Much effort from government laboratories, industry, and academia has been devoted to developing PEM fuel cells, and great advances have been achieved. Although prototype cars powered by fuel cells have been delivered, successful commercialization requires fuel cell electrocatalysts, which are crucial components at the heart of fuel cells, meet exacting performance targets. In this review, we present a brief overview of the recent progress in fuel cell electrocatalysts, which involves catalyst supports, Pt and Pt-based electrocatalysts, and non-Pt electrocatalysts. © The Royal Society of Chemistry 2013.


Xie M.,Heilongjiang University | Xie M.,Harbin Institute of Technology | Fu X.,Heilongjiang University | Jing L.,Heilongjiang University | And 3 more authors.
Advanced Energy Materials | Year: 2014

Different mole ratios of TiO2/BiVO4 nanocomposites with effective contacts have are fabricated by putting BiVO4 nanoparticles into the TiO2 sol, followed by thermal treatment at 450 C. Based on the transient-state surface photovoltage responses and the atmosphere-controlled steady-state surface photovoltage spectra, it is concluded that the photogenerated charge carriers in the TiO2/BiVO4 nanocomposite with a proper mole ratio (5%) display much longer lifetime and higher separation than those in the BiVO4 alone. This is responsible for the unexpected activity for photoelectrochemical oxidation of water, for photocatalytic production of H2, and for photocatalytic degradation of phenol as a model pollutant under visible irradiation. Moreover, it is suggested that the prolonged lifetime and increased separation of photogenerated charges in the fabricated TiO2/BiVO4 nanocomposite is attributed to the unusual spatial transfer of visible-excited high-energy electrons of BiVO4 to TiO2. This work will provide feasible routes to synthesize visible-light responsive nanomaterials for efficient solar utilization. The lifetimes of photogenerated charge carriers of BiVO4 may be prolonged by coupling an appropriate amount of TiO 2. This is attributed to the unusual spatial transfer of visible-light-excited, high-energy electrons of BiVO4 to TiO 2 and is responsible for the unexpectedly high photocatalytic activity for water splitting and pollutant degradation by the fabricated TiO2/BiVO4 nanocomposite. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Kar S.,Harbin Institute of Technology | Jiang Z.,Harbin Institute of Technology | Jiang Z.,Heilongjiang University
Atomic Data and Nuclear Data Tables | Year: 2015

The effect of Debye screening on the doubly excited nonautoionizing 1,3 Pe and 1,3 Do states of two-electron ions has been investigated using highly-correlated exponential wave function within the framework of the Ritz variational principle. The 2pnp 1 Pe (n>3), 2pnp 3 Pe (n≥3) and 2pnd 1,3 Do (n>3) states energies and wavelengths for various transitions in Li+, Be2+, B3+ and C4+ are reported for different screening parameters. The 2pnp 1 Pe (n≥3), 2pnp 3 Pe (n≥2) and 2pnd 1,3 Do (n≥3) states energies and transitions wavelengths for N5+, O6+, F7+ and Ne8+ are also reported as functions of the screening parameters. Transition wavelengths show interesting behavior with increasing screening strength and nuclear charge. •1,3 Pe and 1,3 Do states of plasma-embedded two-electron systems are investigated. © 2014 Elsevier Inc.


Liu X.,Harbin Institute of Technology | Wei F.,Microsoft | Zhang S.,Shanghai JiaoTong University | Zhou M.,Microsoft
ACM Transactions on Intelligent Systems and Technology | Year: 2013

Two main challenges of Named Entity Recognition (NER) for tweets are the insufficient information in a tweet and the lack of training data. We propose a novel method consisting of three core elements: (1) normalization of tweets; (2) combination of a K-Nearest Neighbors (KNN) classifier with a linear Conditional Random Fields (CRF) model; and (3) semisupervised learning framework. The tweet normalization preprocessing corrects common ill-formed words using a global linear model. The KNN-based classifier conducts prelabeling to collect global coarse evidence across tweets while the CRF model conducts sequential labeling to capture fine-grained information encoded in a tweet. The semisupervised learning plus the gazetteers alleviate the lack of training data. Extensive experiments show the advantages of our method over the baselines as well as the effectiveness of normalization, KNN, and semisupervised learning. © 2013 ACM.


Wu L.,Harbin Institute of Technology | Ling J.,University of Notre Dame | Wu Z.-Q.,Hefei University of Technology
Advanced Synthesis and Catalysis | Year: 2011

We report here the first dendritic phosphine-stabilized nickel nanoparticles, which can be prepared from nickel(II) chloride, a third generation phosphine dendrimer and the surfactant tetraoctylammonium bromide (TOABr) by two-phase reduction using sodium borohydride. The resulting nickel nanoparticles are found to be a highly active and recyclable catalyst for Suzuki coupling reactions, especially those extended to aryl chloride substrates, affording the biaryls in moderate to good yields. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Sang F.,Harbin Institute of Technology | Huang X.,Shanghai JiaoTong University | Ren J.,Shanghai JiaoTong University
Electrophoresis | Year: 2014

Semiconductor quantum dots (QDs) are very important luminescent nanomaterials with a wide range of potential applications. Currently, QDs as labeling probes are broadly used in bioassays, including immunoassay, DNA hybridization, and bioimaging, due to their excellent physical and chemical properties, such as broad excitation spectra, narrow and size-dependent emission profiles, long fluorescence life time, and good photostability. The characterization of QDs and their conjugates is crucial for their wide bioapplications. CE has become a powerful tool for the separation and characterization of QDs and their conjugates. In this review, some CE separation models of QDs are first introduced, mainly including CZE, CGE, MEKC, and ITP. And then, some key applications, such as the measurements of size, surface charge, and concentration of QDs and the characterization of QDs conjugates (e.g. QD-protein, QD-DNA, QD-small molecule), are also described. Finally, future perspectives are discussed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhang S.,Harbin Institute of Technology | Zhang S.,Pacific Northwest National Laboratory | Shao Y.,Pacific Northwest National Laboratory | Liao H.,Pacific Northwest National Laboratory | And 3 more authors.
ACS Nano | Year: 2011

Here we report that poly(diallyldimethylammonium chloride) (PDDA) acts as both a reducing agent and a stabilizer to prepare soluble graphene nanosheets from graphite oxide. The results of transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, and Fourier transform infrared indicated that graphite oxide was successfully reduced to graphene nanosheets which exhibited single-layer structure and high dispersion in various solvents. The reaction mechanism for PDDA-induced reduction of exfoliated graphite oxide was proposed. Furthermore, PDDA facilitated the in situ growth of highly dispersed Pt nanoparticles on the surface of graphene nanosheets to form Pt/graphene nanocomposites, which exhibited excellent catalytic activity toward formic acid oxidation. This work presents a facile and environmentally friendly approach to the synthesis of graphene nanosheets and opens up a new possibility for preparing graphene and graphene-based nanomaterials for large-scale applications. © 2011 American Chemical Society.


News Article | April 26, 2016
Site: www.technologyreview.com

Inside a large, windowless room in an electronics factory in south Shanghai, about 15 workers are eyeing a small robot arm with frustration. Near the end of the production line where optical networking equipment is being packed into boxes for shipping, the robot sits motionless. “The system is down,” explains Nie Juan, a woman in her early 20s who is responsible for quality control. Her team has been testing the robot for the past week. The machine is meant to place stickers on the boxes containing new routers, and it seemed to have mastered the task quite nicely. But then it suddenly stopped working. “The robot does save labor,” Nie tells me, her brow furrowed, “but it is difficult to maintain.” The hitch reflects a much bigger technological challenge facing China’s manufacturers today. Wages in Shanghai have more than doubled in the past seven years, and the company that owns the factory, Cambridge Industries Group, faces fierce competition from increasingly high-tech operations in Germany, Japan, and the United States. To address both of these problems, CIG wants to replace two-thirds of its 3,000 workers with machines this year. Within a few more years, it wants the operation to be almost entirely automated, creating a so-called “dark factory.” The idea is that with so few people around, you could switch the lights off and leave the place to the machines. But as the idle robot arm on CIG’s packaging line suggests, replacing humans with machines is not an easy task. Most industrial robots have to be extensively programmed, and they will perform a job properly only if everything is positioned just so. Much of the production work done in Chinese factories requires dexterity, flexibility, and common sense. If a box comes down the line at an odd angle, for instance, a worker has to adjust his or her hand before affixing the label. A few hours later, the same worker might be tasked with affixing a new label to a different kind of box. And the following day he or she might be moved to another part of the line entirely. Despite the huge challenges, countless manufacturers in China are planning to transform their production processes using robotics and automation at an unprecedented scale. In some ways, they don’t really have a choice. Human labor in China is no longer as cheap as it once was, especially compared with labor in rival manufacturing hubs growing quickly in Asia. In Vietnam, Thailand, and Indonesia, factory wages can be less than a third of what they are in the urban centers of China. One solution, many manufacturers—and government officials—believe, is to replace human workers with machines. The results of this effort will be felt globally. Almost a quarter of the world’s products are made in China today. If China can use robots and other advanced technologies to retool types of production never before automated, that might turn the country, now the world’s sweatshop, into a hub of high-tech innovation. Less clear, however, is how that would affect the millions of workers recruited to China’s booming factories. There are still plenty of workers around now as I tour CIG’s factory with the company’s CEO, Gerald Wong, a compact man who earned degrees from MIT in the 1980s. We watch a team of people performing delicate soldering on circuit boards, and another group clicking circuit boards into plastic casings. Wong stops to demonstrate a task that is proving especially hard to automate: attaching a flexible wire to a circuit board. “It’s always curled differently,” he says with annoyance. But there are some impressive examples of automation creeping through Wong’s factory, too. As we walk by a row of machines that stamp chips into circuit boards, a wheeled robot roughly the size of a mini-fridge rolls by ferrying components in the other direction. Wong steps in front of the machine to show me how it will detect him and stop. In another part of the factory, we watch a robot arm grab finished circuit boards from a conveyor belt and place them into a machine that automatically checks their software. Wong explains that his company is testing a robot that does the soldering work we saw earlier more quickly and reliably than a person. After we finish the tour, he says, “It is very clear in China: people will either go into automation or they will go out of the manufacturing business.” China’s economic miracle is directly attributable to its manufacturing industry. Approximately 100 million people are employed in manufacturing in China (in the U.S., the number is around 12 million), and the sector accounts for almost 36 percent of China’s gross domestic product. During the last few decades, manufacturing empires were forged around the Yangtze River Delta, Bohai Bay outside Beijing, and the Pearl River Delta in the south. Millions of low-skilled migrant workers found employment in gigantic factories, producing an unimaginable range of products, from socks to servers. China accounted for just 3 percent of global manufacturing output in 1990. Today it produces almost a quarter, including 80 percent of all air conditioners, 71 percent of all mobile phones, and 63 percent of the world’s shoes. For consumers around the world, this manufacturing boom has meant many low-cost products, from affordable iPhones to flat-screen televisions. In recent years, though, China’s manufacturing engine has started to stall. Wages have increased at a crippling 12 percent per year on average since 2001. Chinese exports fell last year for the first time since the financial crisis of 2009. And toward the end of 2015 the Caixin Purchasing Managers’ Index, a widely used indicator of manufacturing activity, showed that the sector had contracted for the 10th month in a row. Just as China’s manufacturing boom fed the global economy, the prospect of its decline has already started to spook the world’s financial markets. Automation appears to offer an enticing technological solution. China already imports a huge number of industrial robots, but the country lags far behind competitors in the ratio of robots to workers. In South Korea, for instance, there are 478 robots per 10,000 workers; in Japan the figure is 315; in Germany, 292; in the United States it is 164. In China that number is only 36. The Chinese government is keen to change this. On March 16, officials approved the latest Five Year Plan for China’s economy, which is reported to include an initiative that will make billions of yuan available for manufacturers to upgrade to technologies including advanced machinery and robots. The government also plans to create dozens of innovation centers across the country to showcase advanced manufacturing technologies. Some regional authorities in China have been especially bold in their own efforts. Last year the government of Guangdong, a province that contains many large manufacturing operations, promised to spend $150 billion equipping factories with industrial robots and creating two new centers dedicated to advanced automation. The goal is to overtake Germany, Japan, and the United States in terms of manufacturing sophistication by 2049, the 100th anniversary of the founding of the People’s Republic of China. To make that happen, the government needs Chinese manufacturers to adopt robots by the millions. It also wants Chinese companies to start producing more of these robots. The hope is that this will create a virtuous cycle, helping to birth a new high-tech industry and inspiring innovations that could spill over from manufacturing into other sectors and products. Introducing hordes of robot workers is hardly something that can be done overnight, however. That much is clear from the struggles faced by Foxconn, a $130 billion Taiwanese manufacturer famous for employing hundreds of thousands of workers in city-size factories—and for making, among other products, Apple’s iPhones. In 2011, Foxconn’s founder and CEO, Terry Gou, said he expected to have a million robots in his company’s plants by 2014. Three years later, the effort had proved more challenging than expected, and just a few tens of thousands of robots had been deployed. Despite the challenges, Day Chia-peng, general manager of Foxconn’s automation technology development committee, says the company is automating a growing number of tasks on its lines. These include the manufacture of displays and printed circuit boards, although processes that involve bending or snapping components into place still pose challenges. The company is even exploring ways that products themselves can be redesigned to make automated manufacturing easier. And it recently said it will sell some of the robots it has developed in-house to other manufacturers. The transition from human to robot workers may upend Chinese society. Some displaced factory workers could find employment in the service sector, but not all of the 100 million now employed in factories will find such jobs a good match. So a sudden shift toward robots and automation could cause economic hardship and social unrest. “You can make the argument that robotic technology is the way to save manufacturing in China,” says Yasheng Huang, a professor at MIT’s Sloan School of Management. “But China also has a huge labor force. What are you going to do with them?” A few days before visiting CIG, I went to China’s first major robotics event, the World Robot Conference, held inside a vast exhibition hall located within Beijing’s Olympic Park. The city was in the grip of an unusually cold spell, and producing the electricity to meet its heating needs had resulted in lung-searing air pollution from nearby coal power plants. But the snow and smog had done nothing to deter hundreds of researchers and companies, and thousands of attendees, from coming to the event. First came a theatrical opening ceremony, during which a huge video wall showed innovations from China’s ancient history spliced, somewhat oddly, with clips of robots from science fiction movies. The guest list included several high-ranking Chinese politicians. Li Yuanchao, China’s vice president, read messages of congratulations from President Xi Jinping and Premier Li Keqiang. The vice president said that investing in robotics research would not only feed the country’s manufacturing industry but encourage greater domestic innovation. After watching several talks, I wandered past endless demos set up by robot companies and research institutes. I watched as an enormous industrial robot fitted with a fork-like appendage went through some sort of routine factory work at terrifying speed. Other demos were more whimsical, like a small industrial machine performing a mesmerizing rendition of a traditional Chinese dragon dance (in full costume), and a mobile robot equipped with two racquets playing badminton with excited attendees. A humanoid robot with flashing eyes was carrying a small automated vacuum cleaner around on a tray. It was also possible to grasp just how ambitious China will be in trying to replace human workers in its factories. HIT Robot Group, a company affiliated with one of the country’s foremost technical universities, Harbin Institute of Technology, had mocked up a battery production line that itself seemed like one giant robot. Robotic vehicles ferried components between various manufacturing machines. The only spots for humans were inside a control room in the center and on a line where especially fiddly manual work needed to be done. I later learned that HIT estimates the new factory could reduce human labor by as much as 85 percent. But it was also evident that as a country with a history of seemingly endless cheap labor, China had to date been outpaced in the robot revolution. Rethink Robotics, a Boston-­based company, was showing off a pair of flexible and intelligent industrial machines. Unlike conventional industrial robots, these products, called Baxter and Sawyer, require very little programming, and they are equipped with sensors that allow them to recognize objects and avoid hitting people. They also cost between $20,000 and $30,000 instead of the hundreds of thousands typical of an industrial robot. Speaking to me after the event, Rethink founder and robotics pioneer ­Rodney Brooks said that China represents a huge potential market for his company, which recently opened offices in Shanghai. Chinese robot makers are likely to start making more flexible and intelligent robots, too. But for now their products lag behind those of Western manufacturers. “A game we often play when we go to a trade show in the Far East is we go and see the industrial robots from little companies and say, ‘Oh, that’s a copy of that, and that’s a copy of that,’” Brooks said. It will, he suggested, take time for China’s robotics companies to catch up. To see for myself how far China’s researchers have to go, I visited Shanghai Jiao Tong University, one of the country’s most prestigious institutions and home to China’s oldest academic robotics lab, founded in 1979. I found myself on a lush and sprawling campus in a quiet suburb in south Shanghai, surrounded by students cycling around on squeaky bicycles. There, I found a modern-looking building that housed the robotics lab. Zhu Xiangyang, a professor in his late 40s with thin glasses and a fleece sweater-vest, welcomed me to his office with tea and an irrepressible smile. The lab has a few dozen professors and research scientists and more than 100 doctoral and master’s students, and Zhu is justifiably proud of its research. In one room was a brain-controlled robotic wheelchair, operated by means of an electroencephalogram cap worn by a graduate student. A video showed a cyborg cockroach fitted with a wireless implant that connected to its peripheral nervous system and made it possible to control the creature’s movements from a computer. In another room, a researcher demonstrated snakelike and soft-bodied robots capable of reaching or crawling through narrow spaces. Inside a garage, a prototype self-driving car, not unlike one of Google’s, is being developed in collaboration with a Chinese carmaker called Chery. Despite the impressive research projects at places like Jiao Tong, I kept wondering just how China will fulfill its manufacturing ambitions. Kai Yu is the founder of a startup called Horizon Robotics and was previously the head of an AI-focused research lab set up by Baidu, China’s dominant Internet company. Within the Baidu lab, Yu and colleagues were focused on a field of AI called deep learning, which involves training large simulated neural networks to recognize patterns in data. Researchers are now starting to explore how machine learning might make the next generation of industrial robots even smarter and more flexible. “In the future, what I see is China being more creative [in robotics],” Yu told me. “Original design, original ideas, but also some of the fundamental technologies, like deep learning, neural networks, artificial intelligence.” Yu believes that the AI techniques developed by China’s big Internet companies for search, e-commerce, and other purposes could be applied to robots. “China has a very good opportunity to catch up,” he said. “The skills they have learned in the last five years can be transferred to making intelligent machines.” When I later toured CIG’s factory, it wasn’t too hard to imagine how such advances could start feeding into Wong’s efforts to automate his operation. For one thing, a robot capable of learning and adapting presumably wouldn’t be baffled by a misaligned box that needs labeling. After the tour, Wong took me through a PowerPoint presentation that laid out the company’s plan for the next few years, and then the conversation turned to intelligent robotics. “We’re going to use standard robots at first,” Wong said. “But then we’re going to use more advanced ones. More and more, we need to get into more advanced robotics. That can help make a dark factory.” Given the economic imperative, the government’s determination, and the country’s growing technological sophistication, it seems very likely that manufacturing companies across China will automate successfully and that the country will become a leader in the technologies of advanced automation. And yet it’s strange to think about the changes in store for Chinese manufacturing workers. At one point during our tour we had passed a group of about 20 people taking an afternoon break. Everyone was apparently snoozing, heads rested on arms folded in front of them. That’s hardly something a robot needs to do. But I couldn’t help wondering what will happen to these workers once robots have taken their jobs. Wong says they will most likely return to their hometowns and find employment there, on a farm or perhaps in a shop or restaurant. That may be so, but for some it won’t be so simple. A week after leaving China, I received an e-mail from Wong with some more information about his plans, along with a characteristically bold promise. “Stay in touch,” he wrote. “We will make the dark factory happen.”


Xu H.,Harbin Institute of Technology | Spitler J.D.,Oklahoma State University
Renewable Energy | Year: 2014

Predicting ground temperature is an important part of the analysis of geothermal resources assessment and use. Thus, we develop and validate one-dimensional numerical model for heat and mass transfer in partially frozen soils. The model is implemented in HVACSIM Plus and used to simulate the thermal regime of soil profile. In addition to modeling heat conduction, model variations also includes moisture transfer, snow accumulation and melting, and soil freezing and thawing. The results are compared against experimental measurements of ground temperature for three locations in Montana, USA. The differences between simulated depth temperature with and without snow cover and freezing and thawing of soil reveal that ground temperatures are predominantly influenced by these two factors. Considering moisture transfer slightly improves temperature predictions, although it increases computational time by one order of magnitude. To balance computational efficiency with prediction accuracy, we propose an equivalent moisture content of 40-60% saturation in predicting ground temperature. © 2014 Elsevier Ltd.


Fan X.,Harbin Institute of Technology | Au O.C.,Hong Kong University of Science and Technology | Cheung N.M.,Stanford University
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2010

WynerZiv video coding (WZVC) is a newly emerged video coding scheme which compresses the input video frames with the side information (SI) frames only available at the decoder. WZVC exploits the statistics between the source frame and the SI frame at the decoder by utilizing their correlation information. This correlation information is important but also difficult to estimate due to the absence of the SI frame at the encoder, and the lack of the source frame at the decoder. In this paper, we focus on this problem and propose a novel transform-domain adaptive correlation estimation method called TRACE for WZVC. In TRACE, the correlation information is progressively learned during the decoding process of each frame. Within TRACE, we also propose a convex optimization based band-level correlation estimation method which is optimal in the sense of minimizing the theoretical bit rate. Experiments suggest that, when applied in motion compensated interpolation-based low complexity WZVC, TRACE yields competitive results against the state-of-the-art correlation estimation algorithms. More importantly, different from the existing coefficient-level correlation estimation algorithms, the proposed TRACE can be applied in many other WZVC schemes and can provide considerable gain over the popular band-level correlation estimation methods. © 2006 IEEE.


Little A.G.,University of Sydney | Kunisue T.,New York State Department of Health | Kannan K.,New York State Department of Health | Kannan K.,Harbin Institute of Technology | Seebacher F.,University of Sydney
BMC Biology | Year: 2013

Background: Thyroid hormone (TH) is best known for its role in development in animals, and for its control of metabolic heat production (thermogenesis) during cold acclimation in mammals. It is unknown whether the regulatory role of TH in thermogenesis is derived in mammals, or whether TH also mediates thermal responses in earlier vertebrates. Ectothermic vertebrates show complex responses to temperature variation, but the mechanisms mediating these are poorly understood. The molecular mechanisms underpinning TH action are very similar across vertebrates, suggesting that TH may also regulate thermal responses in ectotherms. We therefore aimed to determine whether TH regulates thermal acclimation in the zebrafish (Danio rerio). We induced hypothyroidism, followed by supplementation with 3,5-diiodothyronine (T2) or 3,5,3′-triiodothyronine (T3) in zebrafish exposed to different chronic temperatures. We measured whole-animal responses (swimming performance and metabolic rates), tissue-specific regulatory enzyme activities, gene expression, and free levels of T2 and T3.Results: We found that both T3 and the lesser-known T2, regulate thermal acclimation in an ectotherm. To our knowledge, this is the first such study to show this. Hypothyroid treatment impaired performance measures in cold-acclimated but not warm-acclimated individuals, whereas supplementation with both TH metabolites restored performance. TH could either induce or repress responses, depending on the actual temperature and thermal history of the animal.Conclusions: The low sensitivity to TH at warm temperatures could mean that increasing temperatures (that is, global warming) will reduce the capacity of animals to regulate their physiologies to match demands. We suggest that the properties that underlie the role of TH in thermal acclimation (temperature sensitivity and metabolic control) may have predisposed this hormone for a regulatory role in the evolution of endothermy. © 2013 Little et al.; licensee BioMed Central Ltd.


Chen Y.,Beijing Computational Science Research Center | Zhang B.,Harbin Institute of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We investigate the emission times of high-order harmonics from the asymmetric molecule HeH2 + exposed to intense laser fields numerically and analytically. We show that for each laser cycle, the emission times of harmonics follow two characteristic electron trajectories. The first one matches the prediction of the general ground-state-based quantum orbital theory (GSB-QOT), as the second one differs significantly from the GSB-QOT. We show that the excited state plays an important role in this difference. As a result, the emission times of harmonics can be used as a tool to monitor the dynamics of excited states of the asymmetry molecule in strong laser fields. © 2012 American Physical Society.


Wang M.,Harbin Institute of Technology | Lv G.,Nanjing Southeast University
Nonlinearity | Year: 2010

This paper is concerned with the entire solution of a diffusive and competitive Lotka-Volterra type system with nonlocal delays. The existence of the entire solution is proved by transforming the system with nonlocal delays to a four-dimensional system without delay and using the comparing argument and the sub-super-solution method. Here an entire solution means a classical solution defined for all space and time variables, which behaves as two wave fronts coming from both sides of the x-axis. © 2010 IOP Publishing Ltd & London Mathematical Society.


Li J.H.,Hong Kong University of Science and Technology | Li J.H.,Harbin Institute of Technology | Zhang L.M.,Hong Kong University of Science and Technology
Computers and Geotechnics | Year: 2010

Cracks are common in natural and engineered soils and provide preferential pathways for water infiltration into the soil. Statistical properties of crack geometries are important inputs for analyzing preferential flows in discrete random crack networks. This paper reports the outcome of a field study conducted on a compacted, cracked soil ground at a steady moisture condition. The objectives of the field study were to investigate the crack patterns and probability distributions of the geometric parameters of cracks and to determine the representative elementary volume (REV) of the crack network. The desiccation cracks at the survey site formed an inter-connected columnar structure. The traces of the cracks on the soil surface formed a primary structure consisting of inter-connected crack polygons and a secondary structure comprising of isolated cracks. The locations and orientations of the desiccation cracks followed a uniform distribution, differing from the distribution of fracture sets often observed in fractured rocks. The lengths and apertures of the cracks followed a lognormal distribution as expected. The REV size for the cracked soil was found to be approximately five times the mean crack length, above which the variation in crack porosity in relation to domain size was negligible. © 2010 Elsevier Ltd.


Wang S.,Beihang University | Li Y.,Beihang University | Zhang X.,Harbin Institute of Technology
Materials and Design | Year: 2013

ZrB2-SiC nanocomposite ceramics toughened by ZrO2 fiber were fabricated by spark plasma sintering (SPS) at 1700°C. The content of ZrO2 fiber incorporated into the ZrB2-SiC nanocomposites ranged from 5mass% to 20mass%. The content, microstructure, and phase transformation of ZrO2 fiber exhibited remarkable effects on the fracture toughness of the ZrO2(f)/ZrB2-SiC composites. Fracture toughness of the composites greatly improved to a maximum value of 6.56MPam1/2±0.3MPam1/2 by the addition of 15mass% of ZrO2 fiber. The microstructure of the ZrO2 fiber exhibited certain alterations after the SPS process, which enhanced crack deflection and crack bridging and affected fracture toughness. Some microcracks were induced by the phase transformation from t-ZrO2 to m-ZrO2, which was also an important reason behind the improvement in toughness. © 2013.


Leonov G.A.,Harbin Institute of Technology | Kuznetsov N.V.,University of Jyväskylä | Kuznetsov N.V.,Saint Petersburg State University | Vagaitsev V.I.,University of Jyväskylä | Vagaitsev V.I.,Saint Petersburg State University
Physica D: Nonlinear Phenomena | Year: 2012

The hidden oscillations (a basin of attraction of which does not contain neighborhoods of equilibria) have been obtained first in the 50-60s of the 20th century in automatic control systems with scalar piecewise-linear nonlinearity. This brings up the question about the excitation nature of hidden oscillations. In the present paper it is shown that hidden oscillations can exist not only in systems with piecewise-linear nonlinearity but also in smooth systems. Here the possibility of the existence of a hidden chaotic attractor in a modified Chua's system with a smooth characteristic of nonlinear element is demonstrated. © 2012 Elsevier B.V. All rights reserved.


Tang Z.,Harbin Institute of Technology | Zhang B.,Beihang University
Composites Part B: Engineering | Year: 2012

Macro/micromulti-scale analysis based on the efficient implementation of the Generalized Method of Cells coupled with classical lamination theory was conducted to predict failure of composite laminates, applying failure criteria at the constituent level, including fiber, matrix and interface. Representative unit cells with different fiber arrays were constructed in order to study the effect of reinforcement architecture and failure criteria on strength prediction of composite laminates. In order to compare the micromechanics model's accuracy with commonly-used macroscopic failure theories, the experimental data obtained from the Worldwide Failure Exercise (WWFE) was utilized, and a quantitative assessment method for failure envelopes was developed to evaluate the model's performance. Finally, the types of representative unit cell architectures and failure theories which are applicable for different layups were identified. The results indicate that the predictive performance of the employed micromechanics-based model is closest to the three leading macroscopic failure criteria of Puck, Cuntze and Tsai-Wu, and better than all other microscopic-based failure criteria (Chamis, Mayes, Huang), employed in the WWFE study. © 2011 Elsevier Ltd. All rights reserved.


Mei J.,Nanjing Southeast University | Shen K.,Harbin Institute of Technology | Xiao B.,University of Tennessee at Knoxville | Tolbert L.M.,University of Tennessee at Knoxville | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

This paper presents an improved phase disposition pulsewidth modulation (PWM) (PDPWM) for the modular multilevel converter (MMC) which is based on the selective loop bias mapping (SLBM) method. Its main idea is to change the bias of the PDPWM carrier wave cycling according to the balance situation of the system. This new modulation method can operate at symmetric condition to generate an output voltage with as many as 2N + 1 levels, and by SLBM, the voltages of the upper/lower arm capacitors can be well balanced. Compared to carrier phase-shifted PWM, this method is more easily to be realized and has much stronger dynamic regulation ability. Specially, this method has no issues of sorting, which makes it suitable for MMC with a large number of submodules in one leg. With simulation and experiments, the validity of the proposed method has been shown. © 1982-2012 IEEE.


Yang J.,Harbin Institute of Technology | Li Z.,Harbin Institute of Technology | Li Z.,Hong Kong University of Science and Technology
IEEE/ASME Transactions on Mechatronics | Year: 2011

Reduction of contour error is the main control objective in contour-following applications. A common approach to this objective is to design a controller based on the contour error directly. In this case, the contour error estimation is a key factor in the contour-following operation. Contour error can be approximated by the linear distance from the actual position to the tangent line or plane at the desired position. This approach suffers from a significant error due to linear approximation. A novel approach to contour error calculation of an arbitrary smooth path is proposed in this paper. The proposed method is based on coordinate transformation and circular approximation. In this method, the contour error is represented by the coordinate of the actual position with respect to a specific virtual coordinate frame. The method is incorporated in a position loop-based cross-coupled control structure. An equivalent robust control system is used to establish stability of the closed-loop system. Experimental results demonstrate the efficiency and performance of the proposed contour error estimation algorithm and the motion control strategy. © 2010 IEEE.


Chen Y.,Beijing Computational Science Research Center | Zhang B.,Harbin Institute of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We investigate high-order harmonic generation (HHG) from asymmetric molecules exposed to intense laser fields. We show that the emissions of odd and even harmonics depend differently on the orientation angle, the internuclear distance, as well as the effective charge. This difference mainly comes from different roles of intramolecular interference in the HHG of odd and even harmonics. These roles map the structure of the asymmetric molecule to the odd vs even HHG spectra. © 2011 American Physical Society.


Liu J.,Harbin Normal University | Sun Y.,Harbin Normal University | Li Z.,Harbin Institute of Technology
CrystEngComm | Year: 2012

Flower-like BaTiO 3 nanotube arrays (NTAs) were successfully prepared by a hydrothermal method using TiO 2 NTAs as precursors. Ag-loaded BaTiO 3 NTAs were formed by a photochemical reduction method. The samples were characterized by XRD, SEM, TEM, XPS and UV-vis diffuse reflectance spectra. The results show that Ag nanoparticles can be homogeneously dispersed on the surface of BaTiO 3 NTAs. The loaded Ag exists in the form of a metal. The photocatalytic activity of Ag-BaTiO 3 NTAs was evaluated from the analysis of the photodegradation of methyl orange (MO). It is found that the pH value strongly influences photocatalytic activity of the films, and Ag-BaTiO 3 NTAs perform excellent photocatalytic activity at a low pH value. In addition, the effect of concentration of AgNO 3 dipping solution on the photocatalytic degradation of MO was also studied. © 2012 The Royal Society of Chemistry.


Mei J.,Nanjing Southeast University | Xiao B.,University of Tennessee at Knoxville | Shen K.,Harbin Institute of Technology | Tolbert L.M.,University of Tennessee at Knoxville | Zheng J.Y.,Nanjing Southeast University
IEEE Transactions on Power Electronics | Year: 2013

This paper proposed an improved phase disposition pulse width modulation (PDPWM) for a modular multilevel inverter which is used for Photovoltaic grid connection. This new modulation method is based on selective virtual loop mapping, to achieve dynamic capacitor voltage balance without the help of an extra compensation signal. The concept of virtual submodule (VSM) is first established, and by changing the loop mapping relationships between the VSMs and the real submodules, the voltages of the upper/lower arm's capacitors can be well balanced. This method does not requiring sorting voltages from highest to lowest, and just identifies the MIN and MAX capacitor voltage's index which makes it suitable for a modular multilevel converter with a large number of submodules in one arm. Compared to carrier phase-shifted PWM (CPSPWM), this method is more easily to be realized in field-programmable gate array and has much stronger dynamic regulation ability, and is conducive to the control of circulating current. Its feasibility and validity have been verified by simulations and experiments. © 1986-2012 IEEE.


Li X.,Beijing Jiaotong University | Li J.H.,Harbin Institute of Technology | Zhang L.M.,Hong Kong University of Science and Technology
Computers and Geotechnics | Year: 2014

Experimental evidence shows that a gap-graded soil or a widely-graded granular material may have a bimodal soil-water characteristic curve (SWCC) and a bimodal permeability function. A bimodal SWCC or a bimodal permeability function originates from a dual-porosity structure. To date, the prediction of bimodal SWCCs for gap-graded soils is still a difficult task. In this paper, a bimodal SWCC model is proposed to describe the drying process of granular soils considering a dual-porosity structure. The new SWCC model shows powerful capability in fitting the SWCCs for soils varying from gravel to silt. Regression analysis is conducted to establish empirical relations between the model parameters and the indexes of soil grain-size distribution (GSD). Based on these relations, the new model predicts well both the bimodal SWCCs for gap-graded soils and the unimodal SWCCs for well-graded soils and uniform soils. A bimodal permeability function is also proposed and linked to the new SWCC model. In the absence of experimental SWCCs and permeability functions, the new model can be used to obtain preliminary SWCCs and permeability functions for granular soils. It should be mentioned that the prediction of the SWCC from the GSD is still empirical and does not address the cyclic wetting/drying process. Measurement of the SWCC should be performed wherever an accurate SWCC is required. © 2014 Elsevier Ltd.


Liu G.-H.,Guangxi Normal University | Li Z.-Y.,Minjiang University | Zhang L.,Hong Kong Polytechnic University | Xu Y.,Harbin Institute of Technology
Pattern Recognition | Year: 2011

This paper presents a simple yet efficient image retrieval approach by proposing a new image feature detector and descriptor, namely the micro-structure descriptor (MSD). The micro-structures are defined based on an edge orientation similarity, and the MSD is built based on the underlying colors in micro-structures with similar edge orientation. With micro-structures serving as a bridge, the MSD extracts features by simulating human early visual processing and it effectively integrates color, texture, shape and color layout information as a whole for image retrieval. The proposed MSD algorithm has high indexing performance and low dimensionality. Specifically, it has only 72 dimensions for full color images, and hence it is very efficient for image retrieval. The proposed method is extensively tested on Corel datasets with 15,000 natural images. The results demonstrate that it is much more efficient and effective than representative feature descriptors, such as Gabor features and multi-textons histogram, for image retrieval. © 2010 Elsevier Ltd. All rights reserved.


Li N.,Shanghai Second Polytechnic University | Zhou R.,China Ship Development And Design Center | Hu Q.,Harbin Institute of Technology | Liu X.,Shanghai Second Polytechnic University
Mechanical Systems and Signal Processing | Year: 2012

This paper investigates the application of the redundant second generation wavelet package transform (RSGWPT), neighborhood rough set (NRS) and support vector machine (SVM) on faulty detection, attribute reduction and pattern classification. On this basis, a novel method for mechanical faulty diagnosis based on RSGWPT, NRS and SVM is presented, which utilizes the RSGWPT to extract faulty feature parameters from the statistical characteristics of wavelet package coefficients to constitute feature vectors, and then makes the attribute reduction by NRS method to obtain the key features, lastly these key features are input into SVM to accomplish faulty pattern classification. The experimental results of the proposed method to fault diagnosis of the gearbox and gasoline engine valve trains show that this method can extract the faulty features, which have better classification ability and at the same time reduce a lot of redundant features in case of assuring the classification accuracy, accordingly improve the classifier efficiency and achieve a better classification performance. © 2011 Elsevier Ltd. All rights reserved.


Gu H.,Harbin Institute of Technology | Bi L.,Jilin University | Fu Y.,Harbin Institute of Technology | Wang N.,Harbin Institute of Technology | And 2 more authors.
Chemical Science | Year: 2013

Reversibly fluorescent switchable materials have important applications in the fields of ultrahigh-density optical data storage, molecular switches, logic gates, molecular wires, optical/electronic devices, sensors, bioimaging and so on. Some systems have been developed based on smart luminescent polymers and organic photoswitchable molecules. However, the use of such materials for practical applications is dramatically restricted by their intrinsic drawbacks such as low ON/OFF ratios, irreversibility and poor environmental resistance. An imperative challenge toward real applications is to design and fabricate photoluminescence switching devices with high on/off contrast and fast response time, and especially to obtain multicolored systems, in which the photoluminescence wavelength can be easily tuned in the visible region. Here we report the first inorganic example of a multicolored photoluminescence switching system by controlling the organization of crown-type polyoxometalates (POMs) and CdSe@CdS core-shell quantum dots (QDs) into the layer-by-layer (LBL) nanostructures. The photoluminescence of this system can be switched on and off reversibly upon application of step potentials for different redox states, owing to the energy transfer between reduced POMs and QDs. This system displays a quick response (off 17 s, on 38 s), high on/off contrast (∼91%), good cycling performance (the modulation ratio is only decreased by 19% after 200 cycles) and also has the advantage of low power consumption. Furthermore, reversible four-state fluorescence switching is realized by integrating different-sized QDs in one multifunctional system. This journal is © 2013 The Royal Society of Chemistry.


Guo Y.,New York State Department of Health | Kannan K.,New York State Department of Health | Kannan K.,Harbin Institute of Technology
Analytical and Bioanalytical Chemistry | Year: 2012

Phthalate esters are ubiquitous environmental pollutants and are recognized as environmental endocrine disruptors because of their potential to elicit reproductive and developmental toxicity. Several phthalate esters have been listed by the US Environmental Protection Agency (EPA) as chemicals of concern. Determination of concentrations of phthalate esters in foodstuffs, typically present at sub to low nanogram-per-gram concentrations (between 0.1 and 100 ng g-1), is essential for assessment of human dietary exposure. However, phthalate esters are commonly present as contaminants in several laboratory products, including organic solvents, that are used in sample preparation and analysis. Therefore, accurate analysis of phthalates in food samples is a challenging task. In this review, we summarize the methods available for the determination of phthalate esters in foodstuffs and report on concentrations of phthalates in foodstuffs and potential sources of contamination by phthalates in the analysis of foodstuffs. We offer suggestions to eliminate and/or reduce background levels of contamination by phthalates in the analysis of food and other biological samples. We also introduce methods that are suitable for trace analysis of phthalates in a variety of liquid and solid food samples, in particular, a liquid-liquid extraction method for removal of lipids from food samples, because these can substantially reduce background levels of phthalates in the analytical procedure. © Springer-Verlag 2012.


News Article | March 8, 2016
Site: www.scientificcomputing.com

UNIVERSITY PARK, PA — A computer program that learns and can categorize leaves into large evolutionary categories, such as plant families, will lead to greatly improved fossil identification and a better understanding of flowering plant evolution, according to an international team of researchers. "Paleobotanists have collected many millions of fossil leaves and placed them in the world's museums," said Peter Wilf, professor of geosciences, Penn State. "They represent one of the most underused resources for understanding plant evolution. Variation in leaf shape and venation, whether living or fossil, is far too complex for conventional botanical terminology to capture. Computers, on the other hand, have no such limitation." When botanists identify modern plants, they look at the leaves, but rely mostly on the associated fruits, seeds and flowers to categorize the specimens. In fossil collections, fruits, seeds and flowers are usually much less common than leaves. Even with modern leaves, it is a slow process figuring out which features are botanically informative. If a computer vision approach works on modern leaves, it could help in the classification of fossil leaves as well. "Leaf characterization builds on an 1800's system of description that we call leaf architecture," said Wilf. "It looks at leaf teeth, margins, lobes and venation patterns and uses specialized terminology to describe them. For the most part, this procedure tells us how to describe a leaf, not how to identify one and place it on the tree of life. Cracking the leaf code and accessing the evolutionary information in leaf architecture is the central problem I feel I must try to solve in my career as a paleobotanist." About nine years ago, Wilf learned of an article in the Proceedings of the National Academy of Sciences on a computer vision program that could determine whether or not an animal was in a photograph. "A bell rang in my head," said Wilf. "Instead of an animal, tell me if the image is of an oak leaf or not, or pick among several categories of computers' ability to process and analyze large numbers of specimens, to discover novel visual features that may have phylogenetic significance," said Serre. The researchers currently have a 72-percent accuracy rate over 19 leaf families, compared to about five-percent for random chance. This project is not the first to computerize leaf identification. A popular app, Leafsnap: An Electronic Field Guide, matches the shape of an unknown leaf from a particular region and identifies it down to the species level. However, this current work is the first The variation among the hundreds to thousands of species in a family is many times greater than within a species, and yet, the computer algorithms could learn a set of features and apply it successfully. Because nearly all leaf fossils are of extinct species, family-level identification is usually the first target for paleobotanists. "This approach is a key distinction between what we call image processing, where literally a computer expert programs a computer to see, as opposed to machine learning and computer vision, where the machine is not programmed to exhibit a particular behavior, but rather it learns from examples," said Serre. "Here, our examples were leaf images together with category labels corresponding to family and order." The researchers provide the computer program with half the photos already identified so that it can automatically learn a dictionary of special features, such as vein intersections and tiny bumps and asymmetries, that turn out to matter quite a bit in identifying leaves. The system also learns to disregard the typical problems of low image quality, insect bites and mounting defects. Then the algorithm receives unlabeled test photos and uses its dictionary to identify them. The researchers repeated this procedure 10 times, randomly choosing the training and test images. The results agreed with only one percent difference between the runs. "It normally takes a trained person a few hours to describe one leaf according to the standard protocol, which uses about 50 terms, " said Wilf. "The computer program is thousands of times faster, automatically generates a dictionary of more than 1,000 elements, and then actually shows us what parts of the leaf are diagnostic." Instead of producing only a black box of results, the computer generates a "heat" map directly on the leaf image, identifying and rating areas of importance for correct identification. This approach generates a flood of previously hidden botanical information. Wilf notes that leaf teeth in the rose family have always been considered distinctive, but the heat maps highlight previously unknown features of their tips. Leaves of the coffee family, with 13,000 living species, are very hard to identify when not attached to twigs, but the computer program found it one of the least problematic at 90-percent accuracy. The ability of computer vision to classify leaves quickly and to generate vast quantities of new botanical knowledge will allow scientists to develop more accurate evolutionary pedigrees for plants and plant fossils. Also working on this project were Shengping Zhang, former Brown University postdoctoral fellow, now at the Harbin Institute of Technology, China; Sharat Chikkerur, former graduate student, MIT, now at Microsoft; Stefan A. Little, former postdoctoral fellow, Penn State now at the Université Paris-Sud; and Scott L. Wing, National Museum of Natural History, Smithsonian Institution. The David and Lucile Packard Foundation, a National Science Foundation Early Career Award, a DARPA young investigator award, the Office of Naval Research and the National Natural Science Foundation of China supported this work.


Hu W.,Wuhan University | Liu G.-P.,Harbin Institute of Technology | Zhou H.,University of South Wales
IEEE Transactions on Industrial Electronics | Year: 2013

The design and implementation of Networked Control System Laboratory (NCSLab) 3-D which is a web-based 3-D control laboratory for remote real-time experimentation are introduced in this paper. NCSLab 3-D is built based on the NCSLab framework which supports the structure that the test rigs are located diversely in different parts of the world. In NCSLab 3-D, the test rigs are cataloged into several sublaboratories according to their functionalities. The laboratory building, sublaboratories, and test rigs are modeled in 3-D and reconstructed in a web-based interface using Flash 3-D engines. Users can 'walk into' these laboratories and pick up the test rigs in a virtual reality environment similar to what they do in hands-on laboratories. During the remote experiments, the 3-D models are synchronized with the real test rigs through the network data links. Users are able to zoom in, zoom out, and rotate the 3-D models freely. Therefore, the real-time experiments can be watched from any angles. NCSLab 3-D has been applied to the control engineering education in Wuhan University, China. The results of the teaching practice show that NCSLab 3-D are able to bring great convenience to both users and maintenance personnel and improve the efficiency of the laboratory equipment significantly. © 1982-2012 IEEE.


Dong H.,Harbin Institute of Technology | Dong H.,Northeast Petroleum University | Wang Z.,Tsinghua University | Wang Z.,Brunel University | Gao H.,Harbin Institute of Technology
IEEE Transactions on Industrial Electronics | Year: 2013

This paper is concerned with the distributed H∞ filtering problem for a class of discrete-time Markovian jump nonlinear time-delay systems with deficient statistics of mode transitions. The system measurements are collected through a lossy sensor network subject to randomly occurring quantization errors and randomly occurring packet dropouts. The description of deficient statistics of mode transitions that account for known, unknown, and uncertain transition probabilities is comprehensive. A distributed filter design scheme is outlined by explicitly characterizing the filter gains in terms of some matrix inequalities. Simulation results demonstrate the effectiveness of the proposed filtering scheme. © 1982-2012 IEEE.


Li H.,University of Portsmouth | Li H.,Bohai University | Yu J.,Harbin Institute of Technology | Hilton C.,Protean Electric | Liu H.,University of Portsmouth
IEEE Transactions on Industrial Electronics | Year: 2013

This paper deals with the adaptive sliding-mode control problem for nonlinear active suspension systems via the Takagi-Sugeno (T-S) fuzzy approach. The varying sprung and unsprung masses, the unknown actuator nonlinearity, and the suspension performances are taken into account simultaneously, and the corresponding mathematical model is established. The T-S fuzzy system is used to describe the original nonlinear system for the control-design aim via the sector nonlinearity approach. A sufficient condition is proposed for the asymptotical stability of the designing sliding motion. An adaptive sliding-mode controller is designed to guarantee the reachability of the specified switching surface. The condition can be converted to the convex optimization problems. Simulation results for a half-vehicle active suspension model are provided to demonstrate the effectiveness of the proposed control schemes. © 1982-2012 IEEE.


Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia
Automatica | Year: 2014

We study in this paper the consensus problem for multi-agent systems with agents characterized by high-order linear systems with time delays in both the communication network and inputs. Provided that the open-loop dynamics of the agents is not exponentially unstable, but may be polynomially unstable, and the communication topology contains a directed spanning tree, a truncated predictor feedback approach is established to solve the consensus problem. It is shown that, if the delays are constant and exactly known, the consensus problems can be solved by both full state feedback and observer based output feedback protocols for arbitrarily large yet bounded delays. If it is further assumed that the open-loop dynamics of the agents only contains zero eigenvalues, the delays are allowed to be time-varying and unknown. Numerical examples are worked out to illustrate the effectiveness of the proposed approaches. © 2013 Elsevier Ltd. All rights reserved.


Song H.,Zhejiang University of Finance and Economics | Liu G.-P.,University of South Wales | Liu G.-P.,Harbin Institute of Technology | Yu L.,Zhejiang University of Technology
IEEE Transactions on Industrial Electronics | Year: 2013

This paper studies the design and stability analysis of uncertain networked control systems with multiple feedback channels. An observer-based networked predictive control (NPC) method is proposed to compensate for the distributed delays and packet dropouts in the feedback channels. Sufficient conditions are presented for the closed-loop NPC system with distributed delays and packet dropouts to be stable, both in constant and random cases. A ball-and-beam system is employed to test the proposed method. Both the simulation and experiment results demonstrate the effectiveness of the method. © 1982-2012 IEEE.


Tan C.,Harbin Institute of Technology | Tan C.,Harbin University of Science and Technology | Liu G.-P.,Harbin Institute of Technology | Liu G.-P.,University of South Wales
IEEE Transactions on Automatic Control | Year: 2013

This technical note investigates the problem of consensus for discrete-time networked multi-agent systems (NMASs), where information is exchanged through the network with a communication delay. Based on the networked predictive control scheme and the dynamic output feedback, a novel distributed protocol is proposed to compensate for the network delay actively. For NMASs with a directed topology and non-uniform agents, sufficient conditions of the consensus are obtained. A numerical simulation demonstrates effectiveness of the proposed theoretical results. © 2013 IEEE.


Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Liu M.,Harbin Institute of Technology
IEEE Transactions on Automatic Control | Year: 2012

In this paper, the stability and stabilization problems for a class of switched linear systems with mode-dependent average dwell time (MDADT) are investigated in both continuous-time and discrete-time contexts. The proposed switching law is more applicable in practice than the average dwell time (ADT) switching in which each mode in the underlying system has its own ADT. The stability criteria for switched systems with MDADT in nonlinear setting are firstly derived, by which the conditions for stability and stabilization for linear systems are also presented. A numerical example is given to show the validity and potential of the developed techniques. © 2011 IEEE.


Lau R.Y.K.,University of Hong Kong | Xia Y.,Tsinghua University | Ye Y.,Harbin Institute of Technology
IEEE Computational Intelligence Magazine | Year: 2014

Abstract-There has been a rapid growth in the number of cybercr imes that cause tremendous financial loss to organizations. Recent studies reveal that cybercriminals tend to collaborate or even transact cyber-attack tools via the dark markets established in online social media. Accordingly, it presents unprecedented opportunities for researchers to tap into these underground cybercriminal communities to develop better insights about collaborative cybercrime activities so as to combat the ever increasing number of cybercrimes. The main contribution of this paper is the development of a novel weakly supervised cybercriminal network mining method to facilitate cybercrime forensics. In particular, the proposed method is underpinned by a probabilistic generative model enhanced by a novel context-sensitive Gibbs sampling algorithm. Evaluated based on two social media corpora, our experimental results reveal that the proposed method significantly outperforms the Latent Dirichlet Allocation (LDA) based method and the Support Vector Machine (SVM) based method by 5.23% and 16.62% in terms of Area Under the ROC Curve (AUC), respectively. It also achieves comparable performance as the state-of-the-art Partially Labeled Dirichlet Allocation (PLDA) method. To the best of our knowledge, this is the first successful research of applying a probabilistic generative model to mine cybercriminal networks from online social media. © 2014 IEEE.


Yin S.,Bohai University | Yin S.,Harbin Institute of Technology | Zhu X.,Bohai University | Zhu X.,Harbin Institute of Technology | Kaynak O.,Bogazici University
IEEE Transactions on Industrial Electronics | Year: 2015

Standard partial least squares (PLS) serves as a powerful tool for key performance indicator (KPI) monitoring in large-scale process industry for last two decades. However, the standard approach and its recent modifications still encounter some problems for fault diagnosis related to KPI of the underlying process. To cope with these difficulties, an improved PLS (IPLS) approach is presented in this paper. IPLS is able to decompose the measurable process variables into the KPI-related and unrelated parts, respectively. Based on it, the corresponding test statistics are designed to offer meaningful fault diagnosis information and thus, the corresponding maintenance actions can be further taken to ensure the desired performance of the systems. In order to demonstrate the effectiveness of the proposed approach, a numerical example and Tennessee Eastman (TE) benchmark process are respectively utilized. It can be seen that the proposed approach shows satisfactory results not only for diagnosing KPI-related faults but also for its high fault detection rate. © 2015 IEEE.


Su X.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of South Australia | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2012

In this paper, the problem of l2-l? filtering for a class of discrete-time Takagi-Sugeno (T-S) fuzzy time-varying delay systems is studied. Our attention is focused on the design of full-and reduced-order filters that guarantee the filtering error system to be asymptotically stable with a prescribed H? performance. Sufficient conditions for the obtained filtering error system are proposed by applying an input-output approach and a two-term approximation method, which is employed to approximate the time-varying delay. The corresponding full-and reduced-order filter design is cast into a convex optimization problem, which can be efficiently solved by standard numerical algorithms. Finally, simulation examples are provided to illustrate the effectiveness of the proposed approaches. © 2012 IEEE.


Zhao X.,Bohai University | Zhao X.,University of Hong Kong | Yin S.,Harbin Institute of Technology | Li H.,Bohai University | Niu B.,Bohai University
IEEE Transactions on Automatic Control | Year: 2015

In this technical note, the problem of switching stabilization for slowly switched linear systems is investigated. In particular, the considered systems can be composed of all unstable subsystems. Based on the invariant subspace theory, the switching signal with mode-dependent average dwell time (MDADT) property is designed to exponentially stabilize the underlying system. Furthermore, sufficient condition of stabilization for switched systems with all stable subsystems under MDADT switching is also given. The correctness and effectiveness of the proposed approaches are illustrated by a numerical example. © 2014 IEEE.


Liu Y.-T.,Tsinghua University | Zhu X.-D.,Harbin Institute of Technology | Duan Z.-Q.,Tsinghua University | Xie X.-M.,Tsinghua University
Chemical Communications | Year: 2013

A flexible and robust MoS2-graphene hybrid paper with an excellent lithium storage capacity is fabricated through cross-linking by a polymer ligand, PEO, and shows potential for the development of high-performance film anodes. © 2013 The Royal Society of Chemistry.


Ma Y.,Rice University | Ma Y.,Harbin Institute of Technology | Lewicki R.,Rice University | Razeghi M.,Northwestern University | Tittel F.K.,Rice University
Optics Express | Year: 2013

An ultra-sensitive and selective quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor platform was demonstrated for detection of carbon monoxide (CO) and nitrous oxide (N2O). This sensor used a stateof-the art 4.61 μm high power, continuous wave (CW), distributed feedback quantum cascade laser (DFB-QCL) operating at 10°C as the excitation source. For the R(6) CO absorption line, located at 2169.2 cm-1, a minimum detection limit (MDL) of 1.5 parts per billion by volume (ppbv) at atmospheric pressure was achieved with a 1 sec acquisition time and the addition of 2.6% water vapor concentration in the analyzed gas mixture. For the N2O detection, a MDL of 23 ppbv was obtained at an optimum gas pressure of 100 Torr and with the same water vapor content of 2.6%. In both cases the presence of water vapor increases the detected CO and N2O QEPAS signal levels as a result of enhancing the vibrational-translational relaxation rate of both target gases. Allan deviation analyses were performed to investigate the long term performance of the CO and N2O QEPAS sensor systems. For the optimum data acquisition time of 500 sec a MDL of 340 pptv and 4 ppbv was obtained for CO and N2O detection, respectively. To demonstrate reliable and robust operation of the QEPAS sensor a continuous monitoring of atmospheric CO and N2O concentration levels for a period of 5 hours were performed. © 2013 Optical Society of America.


Dai J.H.,Harbin Institute of Technology | Song Y.,Harbin Institute of Technology | Yang R.,CAS Shenyang Institute of Metal Research
Journal of Physical Chemistry C | Year: 2010

First principles calculations on an Al, Ti, Mn, and Ni doped MgH 2 (110) surface were carried out to study the influence of dopants on the dehydrogenation properties of MgH2. It was shown that Al prefers to substitute for an Mg atom, whereas Ti, Mn, and Ni prefer to occupy interstitial sites. The dopants used different mechanisms to improve the dehydrogenation properties of MgH2. Al weakens the interactions between the Mg and the H atoms in its vicinity and so slightly improved the dehydrogenation properties of the Al doped system. The H atoms near the dopants of the transition metal doped systems were dramatically distorted. Ti has a high potential to generate a TiH2 phase by attracting two H atoms, which frees one H atom from its host Mg atom. The dehydrogenation properties of the Mn doped system were improved by the formation of a Mn-H cluster with a similar structure to Mg3MnH7 but weaker interactions between its atoms. If the MgH2 (110) surface is doped with Ni, the Ni will attract four H atoms to form a regular tetrahedral NiH4 group almost identical in structure to that in Mg2NiH4. The improvement of the dehydrogenation properties of Ni-doped MgH2 is expected as the bonding between the Mg and the H atoms is weakened, and there is a high possibility that the Mg2NiH4 phase will be formed, which is thermodynamically less stable than the MgH2 in this system. © 2010 American Chemical Society.


Zhou B.,Harbin Institute of Technology | Gao H.,Harbin Institute of Technology | Lin Z.,University of Virginia | Duan G.-R.,Harbin Institute of Technology
Automatica | Year: 2012

This paper is concerned with stabilization of a linear system with distributed input delay and input saturation. Both constant and time-varying delays are considered. In the case that the input delay is constant, under the stabilizability assumption on an auxiliary system, it is shown that the system can be stabilized by state feedback for an arbitrarily large delay as long as the open-loop system is not exponentially unstable. In the case that the input delay is time-varying, but bounded, it is shown that the system can be stabilized by state feedback if the non-asymptotically stable poles of the open-loop system are all located at the origin. In both cases, stabilizing controllers are explicitly constructed by utilizing the parametric Lyapunov equation based low gain design approach we recently developed. It is also shown that in the presence of actuator saturation and under the same assumptions on the system, these controllers achieve semi-global stabilization. Some discussions on the assumptions we impose on the system are given. A numerical example illustrates the effectiveness of the proposed stabilization approach. © 2012 Elsevier Ltd. All rights reserved.


Wu L.,Harbin Institute of Technology | Su X.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Qiu J.,Harbin Institute of Technology
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

This paper investigates the problems of stability analysis and stabilization for a class of discrete-time Takagi-Sugeno fuzzy systems with time-varying state delay. Based on a novel fuzzy LyapunovKrasovskii functional, a delay partitioning method has been developed for the delay-dependent stability analysis of fuzzy time-varying state delay systems. As a result of the novel idea of delay partitioning, the proposed stability condition is much less conservative than most of the existing results. A delay-dependent stabilization approach based on a nonparallel distributed compensation scheme is given for the closed-loop fuzzy systems. The proposed stability and stabilization conditions are formulated in the form of linear matrix inequalities (LMIs), which can be solved readily by using existing LMI optimization techniques. Finally, two illustrative examples are provided to demonstrate the effectiveness of the techniques proposed in this paper. © 2010 IEEE.


Yang R.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Liu G.-P.,University of South Wales | Liu G.-P.,Harbin Institute of Technology
IEEE Transactions on Automatic Control | Year: 2011

In this technical note, a new class of discrete-time networked nonlinear systems with mixed random delays and packet dropouts is introduced, and the H∞ filtering problem for such systems is investigated. The mixed stochasitc time-delays consist of both discrete and infinite distributed delays and the packet dropout phenomenon occurs in a random way. Furthermore, new techniques are presented to deal with the infinite distributed delay in the discrete-time domain. Sufficient conditions for the existence of an admissible filter are established, which ensure the asymptotical stability as well as a prescribed H∞ performance. Finally, examples are given to demonstrate the effectiveness of the proposed filter design scheme in this technical note. © 2011 IEEE.


Wu L.,Harbin Institute of Technology | Su X.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Qiu J.,Harbin Institute of Technology
IEEE Transactions on Fuzzy Systems | Year: 2011

This paper is concerned with the problem of ℋ∞ model approximation for discrete-time TakagiSugeno (T-S) fuzzy time-delay systems. For a given stable T-S fuzzy system, our attention is focused on the construction of a reduced-order model, which not only approximates the original system well in an ℋ∞ performance but is also translated into a linear lower dimensional system. By applying the delay partitioning approach, a delay-dependent sufficient condition is proposed for the asymptotic stability with an ℋ∞ error performance for the error system. Then, the ℋ∞ model approximation problem is solved by using the projection approach, which casts the model approximation into a sequential minimization problem subject to linear matrix inequality (LMI) constraints by employing the cone complementary linearization algorithm. Moreover, by further extending the results, ℋ∞ model approximation with special structures is obtained, i.e., delay-free model and zero-order model. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed methods. © 2011 IEEE.


Xu Y.,Sun Yat Sen University | Li Z.,Harbin Institute of Technology
IEEE Transactions on Industrial Electronics | Year: 2015

A microgrid is a promising approach to provide clean, renewable, and reliable electricity by integrating various distributed generations and energy storage systems into power systems. However, highly intermittent renewable generations and various load demands pose new challenges to the optimal resource management in a microgrid. This paper proposes a fully distributed control strategy based on the consensus algorithm for the optimal resource management in an islanded microgrid. The proposed strategy is implemented through a multiagent system framework, which only requires information exchange among neighboring agents through a local network. The objective is achieved through a two-level control strategy. The upper control level is a consensus-based optimization algorithm that discovers the reference of optimal power generation or demand while maintaining the supply-demand balance. The lower control level is responsible for reference tracking of the associated component. Simulation results in the IEEE 14- and 162-bus systems are presented to demonstrate the effectiveness of the proposed control strategy. © 1982-2012 IEEE.


Jiang Y.,Harbin Institute of Technology | Jiang Y.,University of Toronto | Wang Y.,Harbin Institute of Technology | Brudno M.,University of Toronto | Brudno M.,Hospital for Sick Children
Bioinformatics | Year: 2012

Motivation: The development of high-throughput sequencing technologies has enabled novel methods for detecting structural variants (SVs). Current methods are typically based on depth of coverage or pair-end mapping clusters. However, most of these only report an approximate location for each SV, rather than exact breakpoints. Results: We have developed pair-read informed split mapping (PRISM), a method that identifies SVs and their precise breakpoints from whole-genome resequencing data. PRISM uses a split-alignment approach informed by the mapping of paired-end reads hence enabling breakpoint identification ofmultiple SV types, including arbitrary-sized inversions, deletions and tandem duplications. Comparisons to previous datasets and simulation experiments illustrate PRISM's high sensitivity, while PCR validations of PRISM results including previously uncharacterized variants, indicate an overall precision of ∼90%. © The Author 2012. Published by Oxford University Press. All rights reserved.


Pan L.,Tsinghua University | Zhu X.-D.,Harbin Institute of Technology | Xie X.-M.,Tsinghua University | Liu Y.-T.,Tsinghua University
Advanced Functional Materials | Year: 2015

Today, the ever-increasing demand for large-size power tools has provoked worldwide competition in developing lithium-ion batteries having higher energy and power densities. In this context, advanced anode materials are being extensively pursued, among which TiO2 is particularly promising owing to its high safety, excellent cost and environmental performances, and high cycle stability. However, TiO2 is faced with two detrimental deficiencies, that is, extremely low theoretical capacity and conductivity. Herein, a smart hybridization strategy is proposed for the hierarchical co-assembly of TiO2 nanorods and Fe3O4 nanoparticles on pristine graphene nanosheets, aiming to simultaneously address the capacity and conductivity deficiencies of TiO2 by coupling it with high-capacity (Fe3O4) and high-conductivity (pristine graphene) components. The resulting novel, multifunctional ternary heterostructures effectively integrate the intriguing functionalities of the three building blocks: TiO2 as the major active material can adequately retain such merits as high safety and cycle stability, Fe3O4 as the auxiliary active material can contribute extraordinarily high capacities, and pristine graphene as the conductive dopant can guarantee sufficient percolation pathways. Benefiting from a remarkable synergy, the ternary heterostructures deliver superior reversible capacities and rate capabilities, thus casting new light on developing next-generation, high-performance anode materials. A smart hybridization strategy is proposed for the hierarchical co-assembly of TiO2 nanorods and Fe3O4 nanoparticles on pristine graphene nanosheets, aiming to simultaneously address the deficiencies of TiO2 by coupling it with high-capacity (Fe3O4) and high-conductivity (pristine graphene) components. Benefiting from a remarkable synergy, the resulting novel, multifunctional ternary heterostructures deliver superior reversible capacities and rate capabilities, thus casting new light on developing advanced LIB anode materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Li Z.-Y.,Harbin Institute of Technology | Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia
Automatica | Year: 2013

This paper is concerned with exponential stability of a class of integral delay systems with a prescribed decay rate. First, by carefully exploring the literature on this topic, a delay decomposition approach is established to reduce the conservatism in the existing sufficient conditions by constructing new Lyapunov-Krasovskii (LK) functionals. It is proven that the proposed sufficient conditions are less conservative than a recently established set of sufficient conditions. Second, by analyzing the characteristic equation of the considered integral delay system, necessary and sufficient conditions for the stability are obtained by computing the right-most zeros of a certain auxiliary point-delay linear system, for which stability criteria that are easy to test are also established based on this method. Numerical examples illustrate the effectiveness of the obtained results.© 2013 Elsevier Ltd. All rights reserved.


Pan J.-S.,Harbin Institute of Technology | Lee C.-Y.,Lunghwa University of Science and Technology | Meher P.K.,Institute for Infocomm Research
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2013

For cryptographic algorithms, such as elliptic curve digital signature algorithm (ECDSA) and pairing algorithm, the crypto-processors are required to perform large number of additions and multiplications over finite fields of large orders. To have a balanced trade-off between space complexity and time complexity, in this paper, novel digit-serial and digit-parallel systolic structures are presented for computing multiplication over GF(2{m}). Based on novel decomposition algorithm, we have derived an efficient digit-serial systolic architecture, which involves latency of O(\sqrt{m/d}) clock cycles, while the existing digit-serial systolic multipliers involve at least O(m/d) latency for digit-size d. The proposed digit-serial design could be used for AESP-based fields with the same digit-size as the case of trinomial-based fields with a small increase in area. We have also proposed digit-parallel systolic architecture employing n-term Karatsuba-like method, where the latency can be reduced from O(\sqrt{m/d}) to O(\sqrt{m/nd}). This feature would be a major advantage for implementing multiplication for the fields of large orders. From synthesis results, it is shown that the proposed architectures have significantly lower time complexity, lower area-delay product, and higher bit-throughput than the existing digit-serial multipliers. © 2013 IEEE.


Li X.,Harbin Institute of Technology | Gao H.,Bohai University
Automatica | Year: 2013

This paper is concerned with the problem of robust finite frequency (FF) H∞ filtering for uncertain twodimensional (2-D) discrete-time systems in the Fornasini-Marchesini local state-space (FM LSS) model with polytopic uncertain parameters. The goal of the paper is to design filters such that the FF H∞ norm of the filtering error system has a specified upper bound for all uncertainties. In light of a recently developed generalized bounded real lemma, a linear matrix inequality-based approach is proposed for robust FF H∞ filter analysis and design. It is demonstrated that the presented approach to robust FF H∞ filter design covers the latest standard H∞ filtering result. Moreover, it is shown that the existing results specialized for the Roesser model, when applied to the FM LSS model through a model transformation, are much more restrictive than the proposed results in the paper, further justifying this work. © 2013 Elsevier Ltd. All rights reserved.


Zhou B.,Harbin Institute of Technology | Li Z.-Y.,Harbin Institute of Technology | Lin Z.,University of Virginia
Automatica | Year: 2013

This paper is concerned with observer based output feedback control of linear systems with both (multiple) input and output delays. Our recently developed truncated predictor feedback (TPF) approach for state feedback stabilization of time-delay systems is generalized to the design of observers. By imposing some restrictions on the open-loop system, two classes of observer based output feedback controllers, one being finite dimensional and the other infinite dimensional, are constructed. It is further shown that, the infinite dimensional observer based output feedback controllers can be generalized to linear systems with both time-varying input and output delays. It is also shown that the separation principle holds for the infinite dimensional observer based output feedback controllers, but does not hold for the finite dimensional ones. Numerical examples are worked out to illustrate the effectiveness of the proposed approaches. © 2013 Published by Elsevier Ltd.


Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia
IEEE Transactions on Automatic Control | Year: 2014

This technical note is concerned with stabilization of polynomially unstable linear systems with multiple time-varying input delays. A truncated predictor feedback (TPF), which is obtained by truncating the distributed terms in the traditional predictor feedback, is proposed. The proposed TPF is a linear static partial state feedback with a time-varying feedback gain that is constructed from the steady solution to a class of parametric Lyapunov differential equations. Under the assumption that the open-loop system is only polynomially unstable and is uniformly controllable, it is shown that, for sufficiently small value of the design parameter, the resulting closed-loop system is exponentially stable no matter how large the time-varying delays are as long as they are bounded. Simulation demonstrates these theoretical results. © 1963-2012 IEEE.


Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne
International Journal of Robust and Nonlinear Control | Year: 2013

This paper addresses the problem of stability for a class of switched positive linear time-delay systems. As first attempt, the Lyapunov-Krasovskii functional is extended to the multiple co-positive type Lyapunov-Krasovskii functional for the stability analysis of the switched positive linear systems with constant time delay. A sufficient stability criterion is proposed for the underlying system under average dwell time switching. Subsequently, the stability result for system under arbitrary switching is presented by reducing multiple co-positive type Lyapunov-Krasovskii functional to the common co-positive type Lyapunov-Krasovskii functional. A numerical example is given to show the potential of the proposed techniques. Copyright © 2012 John Wiley & Sons, Ltd.


Wang Z.,Tsinghua University | Wang Z.,Brunel University | Dong H.,Northeast Petroleum University | Dong H.,University of Duisburg - Essen | And 2 more authors.
IEEE Transactions on Automatic Control | Year: 2013

In this paper, a new H∞ filtering approach is developed for a class of discrete time-varying systems subject to missing measurements and quantization effects. The missing measurements are modeled via a diagonal matrix consisting of a series of mutually independent random variables satisfying certain probabilistic distributions on the interval [0,1]. The measured output is quantized by a logarithmic quantizer. Attention is focused on the design of a stochastic H∞ filter such that the H∞ estimation performance is guaranteed over a given finite-horizon in the simultaneous presence of probabilistic missing measurements, quantization effects as well as external non-Gaussian disturbances. A necessary and sufficient condition is first established for the existence of the desired time-varying filters in virtue of the solvability of certain coupled recursive Riccati difference equations (RDEs). Owing to its recursive nature, the proposed RDE approach is shown to be suitable for online application without the need of increasing the problem size. The simulation experiment is carried out for the mobile robot localization problem with non-Gaussian disturbances, missing measurements and quantization effects. The effectiveness of the proposed method is demonstrated in the numerical example. © 1963-2012 IEEE.


Yin S.,Bohai University | Yin S.,Harbin Institute of Technology | Luo H.,University of Duisburg - Essen | Ding S.X.,University of Duisburg - Essen
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, two online schemes for an integrated design of fault-tolerant control (FTC) systems with application to Tennessee Eastman (TE) benchmark are proposed. Based on the data-driven design of the proposed fault-tolerant architecture whose core is an observer/residual generator based realization of the Youla parameterization of all stabilization controllers, FTC is achieved by an adaptive residual generator for the online identification of the fault diagnosis relevant vectors, and an iterative optimization method for system performance enhancement. The performance and effectiveness of the proposed schemes are demonstrated through the TE benchmark model. © 2013 IEEE.


Wu L.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of South Australia | Gao H.,Harbin Institute of Technology
IEEE Transactions on Automatic Control | Year: 2010

This paper is concerned with the state estimation and sliding-mode control problems for continuous-time Markovian jump singular systems with unmeasured states. Firstly, a new necessary and sufficient condition is proposed in terms of strict linear matrix inequality (LMI), which guarantees the stochastic admissibility of the unforced Markovian jump singular system. Then, the sliding-mode control problem is considered by designing an integral sliding surface function. An observer is designed to estimate the system states, and a sliding-mode control scheme is synthesized for the reaching motion based on the state estimates. It is shown that the sliding mode in the estimation space can be attained in a finite time. Some conditions for the stochastic admissibility of the overall closed-loop system are derived. Finally, a numerical example is provided to illustrate the effectiveness of the proposed theory. © 2010 IEEE.


Hu J.,Harbin Institute of Technology | Wang Z.,Brunel University | Wang Z.,Tsinghua University | Gao H.,Harbin Institute of Technology | Stergioulas L.K.,Brunel University
Automatica | Year: 2012

In this paper, the extended Kalman filtering problem is investigated for a class of nonlinear systems with multiple missing measurements over a finite horizon. Both deterministic and stochastic nonlinearities are included in the system model, where the stochastic nonlinearities are described by statistical means that could reflect the multiplicative stochastic disturbances. The phenomenon of measurement missing occurs in a random way and the missing probability for each sensor is governed by an individual random variable satisfying a certain probability distribution over the interval [0,1]. Such a probability distribution is allowed to be any commonly used distribution over the interval [0,1] with known conditional probability. The aim of the addressed filtering problem is to design a filter such that, in the presence of both the stochastic nonlinearities and multiple missing measurements, there exists an upper bound for the filtering error covariance. Subsequently, such an upper bound is minimized by properly designing the filter gain at each sampling instant. It is shown that the desired filter can be obtained in terms of the solutions to two Riccati-like difference equations that are of a form suitable for recursive computation in online applications. An illustrative example is given to demonstrate the effectiveness of the proposed filter design scheme. © 2012 Elsevier Ltd. All rights reserved.


Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia | Duan G.-R.,Harbin Institute of Technology
Automatica | Year: 2012

In this paper we study the problem of stabilizing a linear system with a single long time-varying delay in the input. Under the assumption that the open-loop system is stabilizable and not exponentially unstable, a finite dimensional static time-varying linear state feedback controller is obtained by truncating the predictor based controller and by adopting the parametric Lyapunov equation based controller design approach. As long as the time-varying delay is exactly known and bounded, an explicit condition is provided to guarantee the stability of the closed-loop system. It is also shown that the proposed controller achieves semi-global stabilization of the system if its actuator is subject to either magnitude saturation or energy constraints. Numerical examples show the effectiveness of the proposed approach. © 2012 Elsevier Ltd. All rights reserved.


Yang X.-R.,Harbin Institute of Technology | Liu G.-P.,Harbin Institute of Technology | Liu G.-P.,University of South Wales
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2012

For descriptor multi-agent systems with fixed topology and agents described by general descriptor linear time-invariant systems, necessary and sufficient conditions of consensusability with respect to a set of admissible consensus protocols are proposed using the tools of algebra, graph and descriptor linear system theory. The consensusability conditions depend on both the structure properties of each agent's dynamics and the topology within the descriptor multi-agent systems. Designing an output feedback control law can guarantee that the studied descriptor multi-agent system is consensusable with respect to a given admissible set. A provided example indicates the applicability of the proposed approach. © 2012 IEEE.


Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia | Lam J.,University of Hong Kong
Automatica | Year: 2012

This note is concerned with the problem of semi-globally stabilizing a linear system with an input delay and a constraint on the energy of its input. Under the condition of null controllability with vanishing energy, the parametric Lyapunov equation based L2 low gain feedback is adopted to solve the problem. The proposed approach is applied to the linearized model of the relative motion in the orbit plane of a spacecraft with respect to another spacecraft in a circular orbit around the Earth to validate its effectiveness. © 2012 Elsevier Ltd. All rights reserved.


Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Liu M.,Harbin Institute of Technology
Automatica | Year: 2012

In this paper, the stability analysis problem for a class of switched positive linear systems (SPLSs) with average dwell time switching is investigated. A multiple linear copositive Lyapunov function (MLCLF) is first introduced, by which the sufficient stability criteria in terms of a set of linear matrix inequalities, are given for the underlying systems in both continuous-time and discrete-time contexts. The stability results for the SPLSs under arbitrary switching, which have been previously studied in the literature, can be easily obtained by reducing MLCLF to the common linear copositive Lyapunov function used for the system under arbitrary switching those systems. Finally, a numerical example is given to show the effectiveness and advantages of the proposed techniques. © 2012 Elsevier Ltd. All rights reserved.


Wu L.,Harbin Institute of Technology | Su X.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne
Automatica | Year: 2012

In this paper, we investigate the problem of sliding mode control (SMC) of Markovian jump singular time-delay systems. The aim is to consider the bounded ℒ 2 gain performance in the analysis of sliding mode dynamics, thus to improve the transient performance of the SMC system. Firstly, a delay-dependent bounded real lemma is proposed for the underlying system to be stochastically admissible while achieving the prescribed bounded ℒ 2 gain performance condition. An integral-type switching surface function is designed by taking the singular matrix into account, thus the resulting sliding mode dynamics is a full-order singular Markovian jump time-delay system. Then the sliding mode dynamics is analyzed and the solvability condition for the desired switching surface function is derived. Moreover, an SMC law is synthesized to drive the system trajectories onto the predefined switching surface in a finite time. Finally, a numerical example is provided to illustrate the effectiveness of the proposed techniques. © 2012 Elsevier Ltd. All rights reserved.


Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia | Duan G.-R.,Harbin Institute of Technology
IEEE Transactions on Automatic Control | Year: 2011

Low-gain feedback has found several applications in constrained control, robust control, and nonlinear control. In this paper, we first generalize the existing low-gain design methods by introducing the notion of L ∞-vanishment and by providing a full characterization of feedback gains that achieve such a property. We observe that L∞ low-gain feedback can lead to energy peaking, namely, the control energy required by L∞ low-gain feedback increases toward infinity as the low-gain parameter decreases to zero. Motivated by this observation, we consider the notion of L2-vanishment and establish several of its characterizations, based on which a new design approach referred to as the L2 low-gain feedback approach for linear systems is developed. Different from the L∞ low-gain feedback, the L2 low-gain feedback is instrumental in the control of systems with control energy constraints. As an application of L2 low-gain feedback, the problem of semiglobal stabilization of linear systems with control energy constraints is solved in this paper. The notions of L∞ and L 2-vanishment also allow us to establish a systematic approach to the design of L∞ and L2 low-gain feedback. The advantage of this new design approach is that it results in a family of control laws, including those resulting from the existing design methods. © 2011 IEEE.


Jing H.,Harbin Institute of Technology | Liu Z.,Harbin Institute of Technology | Chen H.,Jilin University
IEEE Transactions on Vehicular Technology | Year: 2011

In this paper, a switched control strategy for an antilock braking system (ABS), which has conventional hydraulic actuators equipped with on/off valves, is presented. The investigated system contains the continuous dynamics of the vehicle and the inherent discontinuous characteristics of the on/off valves. Accordingly, a novel approach based on nonlinear state feedback and a switching strategy renders a controller that assures that the wheel slip converges into the target equilibrium set. Then, the convergence condition of the closed-loop system is analyzed using Lyapunov theory in the Filippov framework, and the influence of controller parameters on the system is also discussed. It is shown that the proposed controller has few tuning parameters, and each parameter has an explicit physical meaning. Both the illustrative hardware-in-the-loop simulation and experimental results show that the switched control approach is robust enough to guarantee a good performance, even if the uncertainties of the actuator characteristics, road-adhesion coefficient, and vehicle speed are considered. © 2011 IEEE.


Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia | Duan G.-R.,Harbin Institute of Technology
Journal of Guidance, Control, and Dynamics | Year: 2011

This paper is concerned with spacecraft rendezvous with target spacecraft in an arbitrary elliptical orbit. With three independent control accelerations being the control of the resulting linearized Tschauner-Hempel equations, the spacecraft rendezvous problem can be reformulated as a regulation problem with controls of bounded magnitude and energy. A parametric Lyapunov differential equation approach is proposed in this paper to solve this constrained regulation problem. After establishing the fact that the Tschauner-Hempel equations are both null controllable with controls of bounded magnitude and energy, this paper proves that the proposed linear periodic controller semiglobally stabilizes the system. Equivalently, for any fixed initial conditions, the magnitude and energy of the control can be made as small as desired by tuning some free parameters in the feedback laws. In comparison with the existing quadratic-regulation-based approach, which requires solutions to nonlinear Riccati differential equations, the new approach requires only the solution of linear periodic Lyapunov differential equations, which are investigated in the paper by using the periodic generator approach. Numerical simulations of the nonlinear model of the spacecraft rendezvous instead of a linearized one show that both the magnitude and energy of the control can be reduced to an arbitrarily small level by reducing the values of some parameters in the controller and that the rendezvous mission can be accomplished satisfactorily. Copyright © 2010.


Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia | Duan G.,Harbin Institute of Technology
International Journal of Robust and Nonlinear Control | Year: 2010

This paper studies the problem of stabilizing a linear system with delayed and saturating feedback. It is known that the eigenstructure assignment-based low-gain feedback law (globally) stabilizes a linear system in the presence of arbitrarily large delay in its input, and semi-globally stabilizes it when the input is also subject to saturation, as long as all its open-loop poles are located in the closed left-half plane. Based on a recently developed parametric Lyapunov equation-based low-gain feedback design method, this paper presents alternative, but simpler and more elegant, feedback laws that solve these problems. The advantages of this new approach include its simplicity, the capability of giving explicit conditions to guarantee the stability of the closed-loop system, and the ease in scheduling the low-gain parameter on line to achieve global stabilization in the presence of actuator saturation. Copyright © 2009 John Wiley & Sons, Ltd.


Lu X.,Harbin Institute of Technology | Li H.,Harbin Institute of Technology | Wang B.,Sun Yat Sen University
Journal of the Mechanics and Physics of Solids | Year: 2011

Electric, magnetic and magnetoelectric properties of the nano-structured multiferroic composites were studied by using an energy formulation with the consideration of the surface, interface, and size effect. Coupled thermodynamic evolution equations with respect to the spontaneous polarization and magnetization were established, in which the elastic fields in the matrix and inclusions were solved based on the Eshelbys equivalent inclusion concept and the MoriTanaka method. Physical properties of the composite, such as the spontaneous order parameters, piezoelectric/piezomagnetic properties, and the magnetoelectric coupling effect are highly dependent on the stress state and the microstructures of the nano-composites. Magnetoelectric coupling voltage coefficient was unstable in the vicinity of the critical size and disappeared below the critical size. The model is versatile enough for various composite structures. © 2011 Elsevier Ltd.


Yang R.,Harbin Institute of Technology | Yang R.,University of South Wales | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | And 3 more authors.
Automatica | Year: 2011

This paper deals with the problem of feedback control for networked systems with discrete and distributed delays subject to quantization and packet dropout. Both a state feedback controller and an observer-based output feedback controller are designed. The infinite distributed delay is introduced in the discrete networked domain for the first time. Also, it is assumed that system state or output signal is quantized before being communicated. Moreover, a compensation scheme is proposed to deal with the effect of random packet dropout through communication network. Sufficient conditions for the existence of an admissible controller are established to ensure the asymptotical stability of the resulting closed-loop system. Finally, a numerical example is given to illustrate the proposed design method in this paper. © 2011 Elsevier Ltd. All rights reserved.


Li H.,Harbin Institute of Technology | Li H.,University of Portsmouth | Liu H.,University of Portsmouth | Gao H.,Harbin Institute of Technology | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2012

This paper is focused on reliable fuzzy H ∞ controller design for active suspension systems with actuator delay and fault. The Takagi-Sugeno (T-S) fuzzy model approach is adapted in this study with the consideration of the sprung and the unsprung mass variation, the actuator delay and fault, and other suspension performances. By the utilization of the parallel-distributed compensation scheme, a reliable fuzzy H ∞ performance analysis criterion is derived for the proposed T-S fuzzy model. Then, a reliable fuzzy H ∞; controller is designed such that the resulting T-S fuzzy system is reliable in the sense that it is asymptotically stable and has the prescribed H ∞; performance under given constraints. The existence condition of the reliable fuzzy H ∞; controller is obtained in terms of linear matrix inequalities (LMIs) Finally, a quarter-vehicle suspension model is used to demonstrate the effectiveness and potential of the proposed design techniques. © 2012 IEEE.


Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011

This paper studies the problem of stabilization of discrete-time linear systems with input delay and saturation nonlinearity. By exploring some further intricate properties of the recently developed parametric Lyapunov equation-based low-gain feedback design approach, solutions are proposed to solve the problems by both state feedback and output feedback. This new approach is not only simpler than the existing method that is based on the eigenstructure assignment technique, but also provides explicit conditions on the low-gain parameter to guarantee the stability of the closed-loop system. Moreover, it is possible by adjusting the low-gain parameter online to achieve global results when the system is subject to both input saturation and time-delay. Also, the delay in the input is allowed to be time-varying in some cases. © 2011 IEEE.


Yin S.,Bohai University | Yin S.,Harbin Institute of Technology | Zhu X.,Bohai University
IEEE Transactions on Industrial Electronics | Year: 2015

The particle filter (PF) provides a kind of novel technique for estimating the hidden states of the nonlinear and/or non-Gaussian systems. However, the general PF always suffers from the particle impoverishment problem, which can lead to the misleading state estimation results. To cope with this problem, a modified particle filter, i.e., intelligent particle filter (IPF), is proposed in this paper. It is inspired from the genetic algorithm. The particle impoverishment in general PF mainly results from the poverty of particle diversity. In IPF, the genetic-operators-based strategy is designed to further improve the particle diversity. It should be pointed out that the general PF is a special case of the proposed IPF with the specified parameters. Two experiment examples show that IPF mitigates particle impoverishment and provides more accurate state estimation results compared with the general PF. Finally, the proposed IPF is implemented for real-time fault detection on a three-tank system, and the results are satisfactory. © 2015 IEEE.


Dong H.,Harbin Institute of Technology | Dong H.,Northeast Petroleum University | Wang Z.,Tsinghua University | Wang Z.,Brunel University | Gao H.,Harbin Institute of Technology
IEEE Transactions on Signal Processing | Year: 2012

This paper is concerned with the distributed finite-horizon filtering problem for a class of time-varying systems over lossy sensor networks. The time-varying system (target plant) is subject to randomly varying nonlinearities (RVNs) caused by environmental circumstances. The lossy sensor network suffers from quantization errors and successive packet dropouts that are described in a unified framework. Two mutually independent sets of Bernoulli distributed white sequences are introduced to govern the random occurrences of the RVNs and successive packet dropouts. Through available output measurements from not only the individual sensor but also its neighboring sensors according to the given topology, a sufficient condition is established for the desired distributed finite-horizon filter to ensure that the prescribed average filtering performance constraint is satisfied. The solution of the distributed filter gains is characterized by solving a set of recursive linear matrix inequalities. A simulation example is provided to show the effectiveness of the proposed filtering scheme. © 2012 IEEE.


Patent
Qingdao Headway Technology Co. and Harbin Institute of Technology | Date: 2011-01-05

A micro-current electrolysis-sterilization-algaecide device includes the solution conductivity detector installed in the inlet pipe of the tank, at least a group of electrodes set in the tank in accordance with the order of anode, auxiliary electrode, and cathode, and the controller, which judges the conductance values, controls the electrode polarity and the circuit connections. Said controller includes judging unit to determine the conductance values of water, and according to the results to trigger the corresponding seawater electrolysis-model unit, the fresh water electrolysis-model unit, or the pole-reversing electrolysis-model unit. The device can be used to the seawater and fresh water sterilization algaecide, with good bactericidal algaecide effect, automatic scaling, and a wide range of applications. By adding ultrasonic generator, the device can destroy a variety of bacteria and algae cells. Said device has a simple structure and a wide range of use.


An enzyme-propelled nanorobot: urease-coated nanotubes turn into a propulsion system in a urea-containing liquid because the enzyme breaks down the urea into gaseous products. Since the tubes always have small asymmetries, the reaction products generate a current in the fluid which propels them out of the tube like a jet. Credit: MPI for Intelligent Systems Nanorobots and other mini-vehicles might be able to perform important services in medicine one day – for example, by conducting remotely-controlled operations or transporting pharmaceutical agents to a desired location in the body. However, to date it has been hard to steer such micro- and nanoswimmers accurately through biological fluids such as blood, synovial fluid or the inside of the eyeball. Researchers at the Max Planck Institute for Intelligent Systems in Stuttgart are now presenting two new approaches for constructing propulsion systems for tiny floating bodies. In the case of one motor, the propulsion is generated by bubbles which are caused to oscillate by ultrasound. With the other, a current caused by the product of an enzymatic reaction propels a nanoswimmer. Jet aircraft have led the way. They burn fuel, eject the combustion products in one direction and as a result move in the opposite direction. Researchers at the Max Planck Institute for Intelligent Systems in Stuttgart do it in a very similar way - albeit on a much smaller scale. Their underwater-nanorobot is a single-walled nanotube made of silicon dioxide, a mere 220 nanometres (billionths of a metre) in diameter. A particle of that nature would not normally be able to propel itself in fluids. The scientists therefore coated either only the inner or the inner as well as the outer surface or of the nanotube with the enzyme urease which breaks down urea into ammonia and carbon dioxide. If a nanotube prepared in this way is introduced into a fluid containing urea, this urea is broken down at the urease-coated internal wall. The reaction products generate a current in the fluid which propels them out of the tube like a jet. As such a nanoswimmer either is thinner at one end than at the other or the the urea is not distributed homogeniously over its surface, this results in a thrust, so that the micro-swimmer experiences propulsion in the opposite direction – as in a jet aeroplane. The nanojets reached speeds of 10 micrometres per second, i.e. almost four centimetres per hour. The smallest jet engine in the world Admittedly, coating a nanorobot to achieve a chemical drive is by no means new. However, the tube now presented, with its 220 nanometre opening, represents the smallest jet propulsion system so far constructed in the world. "Our previous record, which is still in the Guinness Book of Records, was around three-times bigger", explains Samual Sanchez who leads the Smart NanoBioDevices Group at the Max Planck Institute for Intelligent Systems in Stuttgart and at the same time holds a professorship at the Institute for Bioengineering of Catalonia in Barcelona. And there is another new aspect of the nanojet which scientists from the Harbin Institute of Technology in Shenzhen in China also helped to develop: for the first time, all the materials and reaction partners used are fully biocompatible. "Previous chemical drives of this kind were usually based on a metallic catalyst at the surface of which hydrogen peroxide was broken down into hydrogen and oxygen molecules", says Sanchez. Oxygen bubbles are created in the process, which creates a thrust in the opposite direction. Both the hydrogen peroxide and the gas bubbles would have disadvantages if used in the human body. But this is not the case with the urease-coated version with its water-soluble – and therefore bubble-free – reaction products. "Urease occurs anyway in the human organism", Sanchez explains. The researchers now want to test the biocompatibility more precisely – and in the process examine whether they can succeed in implanting such micro-tubes into individual cells. "That would be necessary, of course, in order to bring drug molecules to their destination, for example", says Sanchez. While gas bubbles were still unwanted in the approach specified, they form the very centrepiece of a entirely new principle of propulsion for minirobos, which colleagues at the Institute in the Micro, Nano and Molecular Systems Group led by Peer Fischer propose. However, here the gas bubbles are not bubbling freely through the fluid and therefore cannot damage the organism. Rather, the researchers enclose the micro-bubbles in small cylindrical chambers along a plastic strip. To provide the drive, therefore, the gas bubbles expand and contract cyclically because ultrasound causes them to oscillate. As the pulsating bubbles are in chambers open on one side, they only expand through this opening. In the process, they exert a force on the opposite wall of the chamber which propels the plastic strip. In order to achieve propulsion worth mentioning, the researchers arranged several chambers with air bubbles in parallel on their polymer strip. A notable aspect: the sound wave frequency required to cause them to oscillate depends on the size of the tiny bubbles. The bigger the bubbles, the smaller the corresponding resonant frequency. The researchers used this connection to cause their swimmer to rotate alternately clockwise and anti-clockwise. To do so, they placed bubbles of different sizes on the two halves of the four, long cuboid faces divided lengthwise. Two different sound frequencies were then used in a liquid to each cause all the bubbles of one size to oscillate. In this way, the scientists generated thrusts exclusively on one-half of the cuboid face which caused it to rotate on its own axis. This small acoustically driven rotation motor with longitudinal areas each five square millimetres in size achieved up to a thousand rotations per minute in the process. "The variation in the size of the bubbles thereby enables a mini-swimmer to deliberately steer in different directions", says Tian Qiu, who also conducts research at the Max Planck Institute in Stuttgart and played an appreciable role in the study. According to Qiu, a further benefit of the new principle of propulsion is that even swimmers with a complicated geometric structure can be coated with the wafer-thin strips together with chambers for the bubbles. He goes on to explain that the use of ultrasound is also suited to optically impenetrable media such as blood. Light waves, which are also a potential control instrument for micro-drives, can achieve nothing in this case. The researchers now want to use tests in real biological media to check whether the new drive principle is also able to make the most of its advantages in practice. More information: Xing Ma et al. Bubble-Free Propulsion of Ultrasmall Tubular Nanojets Powered by Biocatalytic Reactions, Journal of the American Chemical Society (2016). DOI: 10.1021/jacs.6b06857


Zhao B.,Georgia Institute of Technology | Zhao J.M.,Georgia Institute of Technology | Zhao J.M.,Harbin Institute of Technology | Zhang Z.M.,Georgia Institute of Technology
Applied Physics Letters | Year: 2014

Graphene has been demonstrated as a good candidate for ultrafast optoelectronic devices. However, graphene is essentially transparent in the visible and near infrared with an absorptivity of 2.3%, which has largely limited its application in photon detection. This Letter demonstrates that the absorptance in a monatomic graphene layer can be greatly enhanced to nearly 70%, thanks to the localized strong electric field resulting from magnetic resonances in deep metal gratings. Furthermore, the resonance frequency is essentially not affected by the additional graphene layer. The method presented here may benefit the design of next-generation graphene-based optical and optoelectronic devices. © 2014 AIP Publishing LLC.


Wang B.L.,Harbin Institute of Technology | Han J.C.,Harbin Institute of Technology
International Journal of Heat and Mass Transfer | Year: 2012

This paper investigates the problem of a finite crack in a material layer under the theory of non-Fourier heat conduction. The concept of thermal flow intensity factor is introduced to show the singularity of the thermal flow at the crack tip. Dependence of the crack tip thermal flow field on the thermal flow intensity factor is established in closed-form. Time-varying crack tip thermal flow intensity factors are obtained with sufficient accuracy. In addition to the single crack problem, solution technique and numerical results for the problem of two collinear cracks are given. Effects of crack length and layer thickness on the thermal flow intensity factors are discussed in detail. © 2012 Elsevier Ltd. All rights reserved.


Chang L.,Jilin Normal University | Chen S.,Jilin Normal University | Li X.,Harbin Institute of Technology
Applied Surface Science | Year: 2012

A general fabricating protocol for the preparation of core-shell magnetic molecularly imprinted polymers (MIPs) for chlorinated phenols recognition is described. In this protocol, Fe 3O 4 magnetic nanoparticles were first prepared using the chemical co-precipitation method. Then, the obtained magnetic nanoparticles were coated with a silica shell through modified Stöber method. Finally, MIP films were coated onto the surface of silica-modified magnetic nanoparticles by surface molecular imprinting technique. The resultant polymers showed a high saturation magnetization value (31.350 emu g -1), and short response time (30 s). Meanwhile, the as-synthesized magnetic MIPs showed an excellent recognition and selection properties toward imprinted molecule over structurally related compounds. © 2012 Elsevier B.V.


Lu H.,Harbin Institute of Technology | Huang W.M.,Nanyang Technological University
Smart Materials and Structures | Year: 2013

All amorphous shape memory polymers (SMPs) are featured by their relaxation behavior above and below the switching transition temperature (TSW). Above TSW, the glass transition and secondary transition merge together, resulting in the cooperative (α) movement in polymer macromolecules. Below TSW, movement is non-cooperative (β). In this study, three thermodynamic constitutive frameworks for the shape recovery behavior in amorphous SMPs are proposed based on the Arrhenius, Vogel-Fulcher-Tammann (VFT) and Bässler laws, respectively, and incorporated with parameters (stress, strain and relaxation time) as functions of temperature. The relaxation times of α and β movements satisfy the VFT and Arrhenius laws, respectively. The simulation is compared with the available experimental results reported in the literature for verification. The VFT law is found to be better than the other models, and is able to provide an accurate prediction for the temperature dependent relaxation behavior, from the Arrhenius behavior below, to the Williams-Landel-Ferry behavior above T SW. © 2013 IOP Publishing Ltd.


Guo Z.,Harbin Institute of Technology | Sun J.,Harbin Institute of Technology | Zhang D.,Harbin Institute of Technology | Wu B.,Harbin Institute of Technology
IEEE Transactions on Image Processing | Year: 2012

This paper introduces a class of adaptive Perona-Malik (PM) diffusion, which combines the PM equation with the heat equation. The PM equation provides a potential algorithm for image segmentation, noise removal, edge detection, and image enhancement. However, the defect of traditional PM model is tending to cause the staircase effect and create new features in the processed image. Utilizing the edge indicator as a variable exponent, we can adaptively control the diffusion mode, which alternates between PM diffusion and Gaussian smoothing in accordance with the image feature. Computer experiments indicate that the present algorithm is very efficient for edge detection and noise removal. © 2011 IEEE.


Gu L.,Harbin Institute of Technology | Wang J.,Huazhong University of Science and Technology | Wang J.,Harbin Institute of Technology | Zou Z.,Harbin Institute of Technology | Han X.,Harbin Institute of Technology
Journal of Hazardous Materials | Year: 2014

Anatase TiO2 nanosheets with dominant {001} facets were hybridized with graphitic carbon nitride (g-C3N4) using a facile solvent evaporation method. On top of the superior photocatalytic performance of highly reactive {001} facets, the hybridization with g-C3N4 is confirmed to further improve the reactivity through degrading a series of organic molecules under both UV- and visible-light irradiation. It is proposed that an effective charge separation between g-C3N4 and TiO2 exists in the photocatalytic process, i.e., the transferring of photogenerated holes from the valence band (VB) of TiO2 to the highest occupied molecular orbital (HOMO) of g-C3N4, and the injecting of electrons from the lowest unoccupied molecular orbital (LUMO) of g-C3N4 to the conduction band (CB) of TiO2. Due to this synergistic effect, the enhancement of UV- and visible-light photoactivity over the hybrid is achieved. Furthermore, it has been revealed that holes were the main factor for the improved photoactivity under UV-light, while the OH radicals gained the predominance for degrading organic molecules under visible-light. Overall, this work would be significant for fabricating efficient UV-/visible-photocatalysts and providing deeper insight into the enhanced mechanisms of π-conjugated molecules hybridized semiconductors. © 2014 Elsevier B.V.


Zhao J.M.,Harbin Institute of Technology | Tan J.Y.,Harbin Institute of Technology | Liu L.H.,Harbin Institute of Technology
Journal of Computational Physics | Year: 2013

A new second order form of radiative transfer equation (named MSORTE) is proposed, which overcomes the singularity problem of a previously proposed second order radiative transfer equation [J.E. Morel, B.T. Adams, T. Noh, J.M. McGhee, T.M. Evans, T.J. Urbatsch, Spatial discretizations for self-adjoint forms of the radiative transfer equations, J. Comput. Phys. 214 (1) (2006) 12-40 (where it was termed SAAI), J.M. Zhao, L.H. Liu, Second order radiative transfer equation and its properties of numerical solution using finite element method, Numer. Heat Transfer B 51 (2007) 391-409] in dealing with inhomogeneous media where some locations have very small/zero extinction coefficient. The MSORTE contains a naturally introduced diffusion (or second order) term which provides better numerical property than the classic first order radiative transfer equation (RTE). The stability and convergence characteristics of the MSORTE discretized by central difference scheme is analyzed theoretically, and the better numerical stability of the second order form radiative transfer equations than the RTE when discretized by the central difference type method is proved. A collocation meshless method is developed based on the MSORTE to solve radiative transfer in inhomogeneous media. Several critical test cases are taken to verify the performance of the presented method. The collocation meshless method based on the MSORTE is demonstrated to be capable of stably and accurately solve radiative transfer in strongly inhomogeneous media, media with void region and even with discontinuous extinction coefficient. © 2012 Elsevier Inc.


Zhang Y.,Harbin Institute of Technology | Yi H.-L.,Harbin Institute of Technology | Tan H.-P.,Harbin Institute of Technology
Journal of Computational Physics | Year: 2013

This paper develops a numerical solution to the radiative heat transfer problem coupled with conduction in an absorbing, emitting and isotropically scattering medium with the irregular geometries using the natural element method (NEM). The walls of the enclosures, having temperature and mixed boundary conditions, are considered to be opaque, diffuse as well as gray. The NEM as a meshless method is a new numerical scheme in the field of computational mechanics. Different from most of other meshless methods such as element-free Galerkin method or those based on radial basis functions, the shape functions used in NEM are constructed by the natural neighbor interpolations, which are strictly interpolant and the essential boundary conditions can be imposed directly. The natural element solutions in dealing with the coupled heat transfer problem for the mixed boundary conditions have been validated by comparison with those from Monte Carlo method (MCM) generated by the authors. For the validation of the NEM solution to radiative heat transfer in the semicircular medium with an inner circle, the results by NEM have been compared with those reported in the literatures. For pure radiative transfer, the upwind scheme is employed to overcome the oscillatory behavior of the solutions in some conditions. The steady state and transient heat transfer problem combined with radiation and conduction in the semicircular enclosure with an inner circle are studied. Effects of various parameters such as the extinction coefficient, the scattering albedo, the conduction-radiation parameter and the boundary emissivity are analyzed on the radiative and conductive heat fluxes and transient temperature distributions. © 2013 Elsevier Inc.


Dong H.,Harbin Institute of Technology | Dong H.,Northeast Petroleum University | Wang Z.,Brunel University | Ho D.W.C.,City University of Hong Kong | Gao H.,Harbin Institute of Technology
IEEE Transactions on Signal Processing | Year: 2011

This paper addresses the robust H∞ filtering problem for a class of discrete time-varying Markovian jump systems with randomly occurring nonlinearities and sensor saturation. Two kinds of transition probability matrices for the Markovian process are considered, namely, the one with polytopic uncertainties and the one with partially unknown entries. The nonlinear disturbances are assumed to occur randomly according to stochastic variables satisfying the Bernoulli distributions. The main purpose of this paper is to design a robust filter, over a given finite-horizon, such that the H ∞ disturbance attenuation level is guaranteed for the time-varying Markovian jump systems in the presence of both the randomly occurring nonlinearities and the sensor saturation. Sufficient conditions are established for the existence of the desired filter satisfying the H ∞ performance constraint in terms of a set of recursive linear matrix inequalities. Simulation results demonstrate the effectiveness of the developed filter design scheme. © 2011 IEEE.


Zhang Q.,Harbin Institute of Technology | Xiao J.J.,Harbin Institute of Technology | Zhang X.M.,Harbin Institute of Technology | Yao Y.,Harbin Institute of Technology | Liu H.,Nanjing University
Optics Express | Year: 2013

We present calculations of the optical force on heterodimer of two gold nanorods aligned head-to-tail, under plane wave illumination that is polarized along the dimer axis. It is found that near the dipole-quadrupole Fano resonance, the optical binding force between the nanorods reverses, indicating an attractive to repulsive transition. This is in contrast to homodimer which in similar configuration shows no negative binding force. Moreover, the force spectrum features asymmetric line shape and shifts accordingly when the Fano resonance is tuned by varying the nanorods length or their gap. We show that the force reversal is associated with the strong phase variation between the hybridized dipole and quadrupole modes near the Fano dip. The numerical results may be demonstrated by a nearfield optical tweezer and shall be useful for studying "optical matters" in plasmonics. © 2013 Optical Society of America.


Cheng L.-Y.,Harbin Institute of Technology | Wang H.-F.,Yanbian University | Zhang S.,Harbin Institute of Technology | Zhang S.,Yanbian University | Yeon K.-H.,Chungbuk National University
Optics Express | Year: 2013

We demonstrate efficient schemes of deterministic entanglement generation and quantum state transfer (QST) with the nitrogen-vacancy (NV) centers in diamond confined in separated microtoroidal resonators via single-photon input-output process. Assisted by the polarization of input photon pulse and the electron spin state of NV center, high fidelity NV center entangled states and photonic entangled states can be generated, respectively. The analyses of experimental feasibility show that our schemes work well with low quality resonators and weak coupling between qubits, which may be beneficial for exploring large-scale quantum information processing with diamond-based solid-state devices. © 2013 Optical Society of America.


Cai W.-H.,Harbin Institute of Technology | Li F.-C.,Harbin Institute of Technology | Zhang H.-N.,Harbin Institute of Technology
Journal of Fluid Mechanics | Year: 2010

In order to investigate the turbulent drag reduction phenomenon and understand its mechanism, direct numerical simulation (DNS) was carried out on decaying homogeneous isotropic turbulence (DHIT) with and without polymer additives. We explored the polymer effect on DHIT from the energetic viewpoint, i.e. the decay of the total turbulent kinetic energy and energy distribution at each scale in Fourier space and from the phenomenological viewpoint, i.e. the alterations of vortex structures, the enstrophy and the strain. It was obtained that in DHIT with polymer additives the decay of the turbulent kinetic energy is faster than that in the Newtonian fluid case and a modification of the turbulent kinetic energy transfer process for the Newtonian fluid flow is observed due to the release of the polymer elastic energy into flow structures at certain small scales. Besides, we deduced the transport equations of the enstrophy and the strain, respectively, for DHIT with polymer additives. Based on the analyses of these transport equations, it was found that polymer additives depress both the enstrophy and the strain in DHIT as compared to the Newtonian fluid case, indicating the inhibition effect on small-scale vortex structures and turbulence intensity by polymers. © 2010 Cambridge University Press.


Zhang L.,Harbin Institute of Technology | Gao H.,Harbin Institute of Technology
Automatica | Year: 2010

This paper concerns the asynchronously switched control problem for a class of switched linear systems with average dwell time (ADT) in both continuous-time and discrete-time contexts. The so-called asynchronous switching means that the switchings between the candidate controllers and system modes are asynchronous. By further allowing the Lyapunov-like function to increase during the running time of active subsystems, the extended stability results for switched systems with ADT in nonlinear setting are first derived. Then, the asynchronously switched stabilizing control problem for linear cases is solved. Given the increase scale and the decrease scale of the Lyapunov-like function and the maximal delay of asynchronous switching, the minimal ADT for admissible switching signals and the corresponding controller gains are obtained. A numerical example is given to show the validity and potential of the developed results. © 2010 Elsevier Ltd. All rights reserved.


Wu L.,Harbin Institute of Technology | Ho D.W.C.,City University of Hong Kong
Automatica | Year: 2010

This paper is concerned with the sliding mode control (SMC) of nonlinear singular stochastic systems with Markovian switching. An integral sliding surface function is designed, and the resulting sliding mode dynamics is a full-order Markovian jump singular stochastic system. By introducing some specified matrices, a new sufficient condition is proposed in terms of strict linear matrix inequality (LMI), which guarantees the stochastic stability of the sliding mode dynamics. Then, a SMC law is synthesized for reaching motion. Moreover, when there exists an external disturbance, the ℒ2 disturbance attenuation performance is analyzed for the sliding mode dynamics. Some related sufficient conditions are also established. © 2010 Elsevier Ltd. All rights reserved.


Meng X.,Harbin Institute of Technology | Meng X.,University of Hong Kong | Lam J.,University of Hong Kong | Du B.,University of Hong Kong | Gao H.,Harbin Institute of Technology
Automatica | Year: 2010

This paper revisits the problem of stability analysis for linear discrete-time systems with time-varying delay in the state. By utilizing the delay partitioning idea, new stability criteria are proposed in terms of linear matrix inequalities (LMIs). These conditions are developed based on a novel Lyapunov functional. In addition to delay dependence, the obtained conditions are also dependent on the partitioning size. We have also established that the conservatism of the conditions is a non-increasing function of the number of partitions. Numerical examples are given to illustrate the effectiveness and advantage of the proposed methods. © 2009 Elsevier Ltd. All rights reserved.


Halstead S.J.,Harbin Institute of Technology
Journal of Supercritical Fluids | Year: 2013

This paper reports a molecular dynamics study of the pKW of water, pKa of HCl and pKb of NaOH in supercritical water at a pressure of 1000 atm. The extent of acid/base dissociation is known to be an important factor in the corrosion of supercritical water reaction vessels. This work describes classical molecular dynamics simulations using the SPC/e water model to gain insight into the controlling factors. The results indicate that the dissociation of water has a maximum at 448 K, whereas both the dissociation of HCl and NaOH become less favourable with increasing temperature due to a decrease in entropy. The simulation results are compared to values calculated from the generalised Born theory, and there is a qualitative agreement in the trend. © 2013 Elsevier B.V. All rights reserved.


Liu Y.,Harbin Institute of Technology | Qu S.,Harbin Institute of Technology | Li Y.,Harbin Institute of Technology
Optics Letters | Year: 2013

Single microchannel high-temperature fiber sensors were fabricated by drilling a microchannel across the fiber core near the end of the common single-mode fiber using femtosecond laser-induced water breakdown. Then the microchannel was annealed by the arc discharge to smooth its inwall. The two sides of microchannel and the end surface of the fiber constitute three reflective mirrors, which form a three-wave Fabry-Pérot interferometer (FPI). The fabricated FPI can be used as a high-temperature sensor in harsh environments due to its large temperature range (up to 1000°C), high linearity, miniaturized size, and perfect mechanical property. © 2013 Optical Society of America.


Zhou B.,Harbin Institute of Technology | Duan G.-R.,Harbin Institute of Technology | Lam J.,University of Hong Kong
Automatica | Year: 2010

By exploring some geometric properties of the logarithmic quantizer and using the fact that the logarithmic quantizer is sector bounded and nondecreasing, this paper presents a new approach to the stability analysis of quantized feedback control systems. Our method is based on Tsypkin-type Lyapunov functions that have been widely used in absolute stability analysis problems. The results are expressed in linear matrix inequalities (LMIs) and are valid for both single-input and multiple-input discrete-time linear systems with a logarithmic quantizer. Both theoretical analysis and numerical examples show that the results in this paper are generally less conservative than those in the quadratic framework. © 2009 Elsevier Ltd. All rights reserved.


Xu Y.,Harbin Institute of Technology | Zhang D.,Hong Kong Polytechnic University
Optical Engineering | Year: 2010

Multibiometrics can obtain a higher accuracy than the single biometrics by simultaneously using multiple biometric traits of the subject. We note that biometric traits are usually in the form of images. Thus, how to properly fuse the information of multiple biometric images of the subject for authentication is crucial for multibiometrics. We propose a novel image-based linear discriminant analysis (IBLDA) approach to fuse two biometric traits (i.e., bimodal biometric images) of the same subject in the form of matrix at the feature level. IBLDA first integrates two biometric traits of one subject into a complex matrix and then directly extracts low-dimensional features for the integrated biometric traits. IBLDA also enables more information to be exploited than the matching score level fusion and the decision level fusion. Compared to linear discriminant analysis (LDA), IBLDA has the following advantages: First, it can overcome the small sample size problem that conventional LDA usually suffers from. Second, IBLDA solves the eigenequation at a low computational cost. Third, when storing the scatter matrices IBLDA will not bring as heavy a memory burden as conventional LDA. We also clearly show the theoretical foundation of the proposed method. The experiment result shows that the proposed method can obtain a high classification accuracy. © 2010 Society of Photo-Optical Instrumentation Engineers.


Han Y.,Harbin Institute of Technology | Zhao X.,Harbin Institute of Technology | Qu S.,Harbin Institute of Technology
Optics Express | Year: 2011

We report on the formation of polarization dependent ripples on ZF 6 glass by femtosecond laser irradiation. Two kinds of polarization dependent ripples are formed on the laser modified region. The ripples with direction parallel to laser polarization distribute in a pit in the center of laser modified region, the period of the ripples increases with the increasing pulse number. The ripples with direction perpendicular to laser polarization spread around the pit, the period of the ripples (∼750nm) almost keeps constant with the increasing pulse number. © 2011 Optical Society of America.


Liu W.,Harbin Institute of Technology | Liu Z.,Harbin Institute of Technology | Liu S.,Harbin Institute of Technology
Optics Letters | Year: 2013

We propose an asymmetric optical image encryption scheme that uses an amplitude and phase mixture retrieval of the Yang-Gu algorithm. The encryption process is realized by employing a cascaded Yang-Gu algorithm together with two random phase masks that serve as the public encryption keys. The two private keys are generated in the encryption process and are randomly distributed binary matrices to be used for performing one-way binary phase modulations. Without the private keys, illegal users cannot retrieve the secret image. Numerical simulations are carried out to demonstrate the validity and security of the proposed scheme. © 2013 Optical Society of America.


Zhang Q.,Harbin Institute of Technology | Xiao J.J.,Harbin Institute of Technology
Optics Letters | Year: 2013

We study the optical far-field and near-field characteristics, and the optical force effects of plasmonic disk-ring nanostructures. There are multiple Fano features resulting from the scattering interferences of the hybridized modes from the disk's dipole and the ring's higher-order modes. In particular, it is found that the optical binding force between the disk and the ring shows multiple sign reversals spectrally, from the dipole-quadrupole regime up to the dipole-decapole regime. We show that the zero-force points can be categorized into two types: the positive-to-negative ones resulting from the Fano dip and the negative-to-positive ones associated with the transitions between dipole-multipole modes. The multiple sign reversals of the optical forces are tunable by the geometrical size and gap of the disk and ring. Such characters make it possible to organize unusual optical matters from individual plasmonic nanoparticles. © 2013 Optical Society of America.


Zhang Y.,Harbin Institute of Technology | Yi H.,Harbin Institute of Technology | Tan H.,Harbin Institute of Technology
Optics Express | Year: 2013

The lattice Boltzmann method (LBM) is extended to solve transient radiative transfer in one-dimensional slab containing scattering media subjected to a collimated short laser irradiation. By using a fully implicit backward differencing scheme to discretize the transient term in the radiative transfer equation, a new type of lattice structure is devised. The accuracy and computational efficiency of this algorithm are examined firstly. Afterwards, effects of the medium properties such as the extinction coefficient, the scattering albedo and the anisotropy factor, and the shapes of laser pulse on time-resolved signals of transmittance and reflectance are investigated. Results of the present method are found to compare very well with the data from the literature. For an oblique incidence, the LBM results in this paper are compared with those by Monte Carlo method generated by ourselves. In addition, transient radiative transfer in a two-Layer inhomogeneous media subjected to a short square pulse irradiation is investigated. At last, the LBM is further extended to study the transient radiative transfer in homogeneous medium with a refractive index discontinuity irradiated by the short pulse laser. Several trends on the timeresolved signals different from those for refractive index of 1 (i.e. refractive-index-matched boundary) are observed and analysed. ©2013 Optical Society of America.


Liu T.,Harbin Institute of Technology | Tan J.,Harbin Institute of Technology | Liu J.,Harbin Institute of Technology | Wang H.,Harbin Institute of Technology
Optics Letters | Year: 2013

A high NA Fresnel zone plate (FZP) is studied using vectorial angular spectrum theory for realizing the sharpest possible super-Gaussian optical needle with purely longitudinal polarization illuminated by a radially polarized vector beam. Strong dispersion of the FZP results in a light field resembling a super-Gaussian optical needle by selecting an optimal FZP structural wavelength relative to the illumination wavelength and inserting a narrow comb window function into the center-shaded FZP. A 25 μm long longitudinally polarized flattop optical needle with a transverse beam width of about 0.366? is focused at a distance of 222.5 μm away from a binary amplitude 3.46 mm diameter FZP for a 532.4 nm wavelength in free space. © 2013 Optical Society of America.


Xing L.,Harbin Institute of Technology | Xu Y.,Harbin Institute of Technology | Wang R.,Harbin Institute of Technology | Xu W.,Harbin Institute of Technology
Optics Letters | Year: 2013

The temperature dependence of upconversion luminescence in Ho3Yb3Tm3 tri-doped LiNbO3 single crystal was studied at different temperatures from 289 to 773 K under 980 nm excitation. The tri-doped LiNbO3 single crystal offers temperature-dependent color tuning properties, and the white-light emission can be obtained by simply tuning the temperature. In addition, the competition between nonradiative transition and thermal population plays an important role in the upconversion process with temperature increase. This research has implications in the extension of research for optical temperature sensors and multicolor variable temperature display materials. © 2013 Optical Society of America.


Liu T.,Harbin Institute of Technology | Tan J.,Harbin Institute of Technology | Liu J.,Harbin Institute of Technology | Wang H.,Harbin Institute of Technology
Optics Express | Year: 2013

A design and optimization method based on vectorial angular spectrum theory is proposed in this paper for the vectorial design of a superoscillatory lens (SOL), so that the radially polarized vector beam can be tightly focused. The structure of a SOL is optimized using genetic algorithm and the computational process is accelerated using fast Hankel transform algorithm. The optimized results agree well with what is obtained using the vectorial Rayleigh-Sommerfeld diffraction integral. For an oil immersed SOL, a subwavelength focal spot of about 0.25 illumination wavelength without any significant side lobe can be created at a distance of 184.86μm away from a large SOL with a diameter of 1mm. The proposed vectorial design method can be used to efficiently design a SOL of arbitrary size illuminated by various vector beams, with the subwavelength hotspot located in a post-evanescent observation plane. © 2013 Optical Society of America.


Song Q.,Harbin Institute of Technology | Zeng C.,Harbin Institute of Technology | Xiao S.,Harbin Institute of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

The phenomenon of dynamical tunneling is investigated in asymmetric resonant cavities by exploiting the avoided resonance crossing. With the external coupling between resonances localized within different regions of phase space, we show that the tunneling rate can be dramatically reduced. The nearly complete suppression of dynamical tunneling, so-called "locking," has been achieved under two-state weak coupling. A possible way to observe and control the coherent destruction of dynamical tunneling experimentally is also presented. Our research may find application in Q switching and ultrafast beam steering of microcavity lasers. © 2013 American Physical Society.


Wu L.,Harbin Institute of Technology
International Journal of Engineering Science | Year: 2010

A new method is developed to derive the bounds of the effective thermal conductivity of composites with ellipsoidal inclusions. The transition layer for each ellipsoidal inclusion is introduced to make the trial temperature field for the upper bound and the trial heat flux field for the lower bound satisfy the continuous interface conditions which are absolutely necessary for the application of variational principles. According to the principles of minimum potential energy and minimum complementary energy, the bounds of the effective thermal conductivity of composites with ellipsoidal inclusions are rigorously derived. The effects of the distribution and geometric parameters of ellipsoidal inclusions on the bounds of the effective thermal conductivity of composites are analyzed. It should be shown that the present method is simple and needs not calculate the complex integrals of multi-point correlation functions. Meanwhile, the present method provides a powerful way to bound the effective thermal conductivity of composites, which can be developed to obtain a series of bounds by taking different trial temperature and heat flux fields. In addition, the present upper and lower bounds still are finite when the thermal conductivity of ellipsoidal inclusions tends to ∞ and 0, respectively. © 2009 Elsevier Ltd. All rights reserved.


Zhan K.,China University of Petroleum - East China | Hou C.,Harbin Institute of Technology
Optics Express | Year: 2014

We study theoretically surface lattice solitons driven by quadratic electro-optic effect at the interface between an optical lattice and diffusive nonlinear media with self-focusing and self-defocusing saturable nonlinearity. Surface solitons originating from self-focusing nonlinearity can be formed in the semi-infinite gap, and are stable in whole domain of their existence. In the case of self-defocusing nonlinearity, both surface gap and twisted solitons are predicted in first gap. We discover that surface gap solitons can propagate stably in whole existence domain except for an extremely narrow region close to the Bloch band, and twisted solitons are linearly unstable in the entire existence domain. © 2014 Optical Society of America.


Wu L.,Harbin Institute of Technology
International Journal of Engineering Science | Year: 2010

A new model is developed to bound the effective thermal conductivity of composites with thermal contact resistance between spherical inclusions and matrix. To construct the trial temperature and heat flux fields which satisfy the necessary interface conditions, the transition layer for each spherical inclusion is introduced. For the upper bound, the trial temperature field needs to satisfy the thermal contact resistance conditions between spherical inclusions and transition layers and the continuous interface conditions between transition layers and remnant matrix. For the lower bound, the trial heat flux field needs to satisfy the continuous interface conditions between different regions. It should be pointed out that the continuous interface conditions mentioned above are absolutely necessary for the application of variational principles, and the thermal contact resistance conditions between spherical inclusions and transition layers are suggested by the author. According to the principles of minimum potential energy and minimum complementary energy, the bounds of the effective thermal conductivity of composites with imperfect interfaces are rigorously derived. The effects of the size and distribution of spherical inclusions on the bounds of the effective thermal conductivity of composites are analyzed. It should be shown that the present method is simple and does not need to calculate the complex integrals of multi-point correlation functions. Meanwhile, the present method provides an entirely different way to bound the effective thermal conductivity of composites with imperfect interface, which can be developed to obtain a series of bounds by taking different trial temperature and heat flux fields. In addition, the present upper and lower bounds are finite when the thermal conductivity of spherical inclusions tends to ∞ and 0, respectively. © 2010 Elsevier Ltd. All rights reserved.


Zhai X.,Harbin Institute of Technology | Stewart M.G.,University of Newcastle
Engineering Structures | Year: 2010

The safety and reliability of reinforced grouted concrete block masonry is not accurately known in China. The present paper develops a probabilistic model to calculate the structural reliability of typical reinforced grouted concrete block masonry walls designed to Chinese standards, loaded concentrically and eccentrically in compression. The effect of probability distribution of model error, material strengths, live load type, structural safety class, live-to-dead ratio, reinforcement ratio, discretization of wall thickness, eccentricity and load effect combination were considered when calculating the structural reliability of reinforced grouted concrete block masonry walls in compression. When using the recommended distribution of model error for typical structures the existing (design) safety levels were found to be close to the target reliability for concentric compression for second class safety grade structures which comprise the majority of building stock in China. However, the reliability-based code calibration showed that design loads could be increased and decreased by 13.6% and 16.7% for first and third class safety grade structures, respectively. © 2009 Elsevier Ltd.


Semi-globally input-to-state stable (ISS) control law is derived for flexible spacecraft attitude maneuvers in the presence of parameter uncertainties and external disturbances. The modified rodrigues parameters (MRP) are used as the kinematic variables since they are nonsingular for all possible rotations. This novel simple control is a proportional-plus-derivative (PD) type controller plus a sign function through a special Lyapunov function construction involving the sum of quadratic terms in the angular velocities, kinematic parameters, modal variables and the cross state weighting. A sufficient condition under which this nonlinear PD-type control law can render the system semi-globally input-to-state stable is provided such that the closed-loop system is robust with respect to any disturbance within a quantifiable restriction on the amplitude, as well as the set of initial conditions, if the control gains are designed appropriately. In addition to detailed derivations of the new controllers design and a rigorous sketch of all the associated stability and attitude convergence proofs, extensive simulation studies have been conducted to validate the design and the results are presented to highlight the ensuring closed-loop performance benefits when compared with the conventional control schemes. © 2009 Elsevier Ltd. All rights reserved.


Lu H.,Harbin Institute of Technology | Huang W.M.,Nanyang Technological University
Smart Materials and Structures | Year: 2013

We present a phenomenological approach to study the viscoelastic transition and working mechanism of the chemo-responsive shape memory effect (SME) in amorphous shape memory polymers (SMPs). Both the copolymerization viscosity model and Doolittle equation are initially applied to quantitatively identify the influential factors behind the chemo-responsive SME in the SMPs exposure to a right solvent. After this, the Williams-Landel-Ferry (WLF) equation is employed to couple the viscosity (η), time-temperature shift factor (ατ) and glass transition temperature (Tg) in amorphous polymers. By means of combining the WLF and Arrhenius equations together, the inductively decreased transition temperature is confirmed as the driving force for the chemo-responsive SME. Finally, a phenomenological viscoelastic model is proposed and then verified by the available experimental data reported in the literature and then compared with the simulation results of a semi-empirical model. This phenomenological model is expected to provide a powerful simulation tool for theoretical prediction and experimental substantiation of the chemo-responsive SME in amorphous SMPs by viscoelastic transition. © 2013 IOP Publishing Ltd.


Song F.,CAS Institute of Mechanics | Meng S.,Harbin Institute of Technology | Xu X.,CAS Institute of Mechanics | Shao Y.,CAS Institute of Mechanics
Physical Review Letters | Year: 2010

We propose here a new method to make ceramics insensitive to thermal shock up to their melting temperature. In this method the surface of ceramics was biomimetically roughened into nanofinned surface that creates a thin air layer enveloping the surface of the ceramics during quenching. This air layer increases the heat transfer resistance of the surface of the ceramics by about 10000 times so that the strong thermal gradient and stresses produced by the steep temperature difference in thermal shock did not occur both on the actual surface and in the interior of the ceramics. This method effectively extends the applications of existing ceramics in the extreme thermal environments. © 2010 The American Physical Society.


Chen J.-X.,Northeastern University China | Zhu Z.-L.,Northeastern University China | Liu Z.,Harbin Institute of Technology | Fu C.,Northeastern University China | And 2 more authors.
Optics Express | Year: 2014

Recently, a number of double-image cryptosystems have been developed. However, there are notable security performance differences between the two encryption channels in these algorithms. This weakness downgrades the security level and practicability of these cryptosystems, as the cryptosystems cannot guarantee all the input images be transmitted in the channel with higher security level. In this paper, we propose a novel double-image encryption scheme based on cross-image pixel scrambling in gyrator domains. The two input images are firstly shuffled by the proposed cross-image pixel scrambling approach, which can well balance the pixel distribution across the input images. The two scrambled images will be encoded into the real and imaginary parts of a complex function, and then converted into gyrator domains. An iterative architecture is designed to enhance the security level of the cryptosystem, and the cross-image pixel scrambling operation is performed to the real and imaginary parts of the generated complex encrypted data in each round. Numerical simulation results prove that a satisfactory and balanced security performance can be achieved in both channels. © 2014 Optical Society of America.


Zang J.,Beijing Key Laboratory for Terahertz Spectroscopy and Imaging | Xie Z.,Harbin Institute of Technology | Zhang Y.,Beijing Key Laboratory for Terahertz Spectroscopy and Imaging | Zhang Y.,Harbin Institute of Technology
Optics Letters | Year: 2013

A simple optical image encryption system with spatially incoherent illumination is proposed. Only one Fourier lens and one random phase plate are contained in this system. The original image is perturbed by a random phase-only mask located on the aperture plane. The encrypted information is the only intensity distribution that can be directly recorded by a CCD or CMOS. The decryption procedure can be performed digitally and the random phase distribution works as the decryption key. Numerical simulations and experimental results demonstrate the validity of the proposed method. © 2013 Optical Society of America.


Wang C.,Harbin Institute of Technology | Wang D.,Harbin Institute of Technology | Wang Q.,Harbin Institute of Technology | Chen H.,Harbin Institute of Technology
Journal of Power Sources | Year: 2010

Three-dimensional porous NiO is prepared on Ni foam by a thermal treatment method at various temperatures. The morphology and structure of porous NiO are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The electrochemical properties of three-dimensional porous NiO anode are evaluated by galvanostatic discharge-charge cycling, cyclic voltammery, and impedance spectral measurements on cells with lithium as the counter and reference electrodes. Results show that porous NiO delivers a stable capacity of 520 ± 20 mAh g-1 with no noticeable capacity fading up to 30 cycles when cycled in the voltage range 0.05-3.0 V at rate of 0.2 C. The porous NiO exhibits higher reversible capacity, better cycleability, as well as higher rate capability in comparison to NiO foil. The observed cyclic voltammograms and impedance spectra are analyzed and interpret a redox reaction of NiO-Ni0 with formation and decomposition of Li2O. The excellent electrochemical performance of porous NiO can be attributed to its large surface area, which lowers the current density of NiO reaction interface, and then an alternative anode is provided for lithium-ion batteries. © 2010 Elsevier B.V.


Dai C.,Harbin Institute of Technology | Chen Z.,Harbin Institute of Technology | Jin H.,Harbin Institute of Technology | Hu X.,Harbin Institute of Technology
Journal of Power Sources | Year: 2010

In order to search for cathode materials with better performance, Li3(V1-xMgx)2(PO4)3 (0, 0.04, 0.07, 0.10 and 0.13) is prepared via a carbothermal reduction (CTR) process with LiOH·H2O, V2O5, Mg(CH3COO)2·4H2O, NH4H2PO4, and sucrose as raw materials and investigated by X-ray diffraction (XRD), scanning electron microscopic (SEM) and electrochemical impedance spectrum (EIS). XRD shows that Li3(V1-xMgx)2(PO4)3 (x = 0.04, 0.07, 0.10 and 0.13) has the same monoclinic structure as undoped Li3V2(PO4)3 while the particle size of Li3(V1-xMgx)2(PO4)3 is smaller than that of Li3V2(PO4)3 according to SEM images. EIS reveals that the charge transfer resistance of as-prepared materials is reduced and its reversibility is enhanced proved by the cyclic votammograms. The Mg2+-doped Li3V2(PO4)3 has a better high rate discharge performance. At a discharge rate of 20 C, the discharge capacity of Li3(V0.9Mg0.1)2(PO4)3 is 107 mAh g-1 and the capacity retention is 98% after 80 cycles. Li3(V0.9Mg0.1)2(PO4)3//graphite full cells (085580-type) have good discharge performance and the modified cathode material has very good compatibility with graphite. © 2010 Elsevier B.V. All rights reserved.


Yin S.,Harbin Institute of Technology | Huang Z.,Harbin Institute of Technology
IEEE/ASME Transactions on Mechatronics | Year: 2015

This paper focuses on fault detection and isolation for vehicle suspension systems. The proposed method is divided into three steps: 1) confirming the number of clusters based on principal component analysis; 2) detecting faults by fuzzy positivistic C-means clustering and fault lines; and 3) isolating the root causes for faults by utilizing the Fisher discriminant analysis technique. Different from other schemes, this method only needs measurements of accelerometers that are fixed on the four corners of a vehicle suspension. Besides, different spring attenuation coefficients are regarded as a special failure instead of several ones. A full vehicle benchmark is applied to demonstrate the effectiveness of the method. © 1996-2012 IEEE.


Zhou B.,Harbin Institute of Technology
Systems and Control Letters | Year: 2015

This paper studies stabilization of linear systems with both state and input delays. A dynamic input-delay compensator obtained by adding integrators is established to compensate the input delays that can be arbitrarily large. With the input delay compensator, the original stabilization problem reduces to the problem of stabilizing an augmented linear time-delay system without input delay. Three methods are also proposed to design stabilizing controllers for the augmented linear time-delay system. The first method is based on linear matrix inequalities (LMIs) and the second method is based on model reduction. The third method is based on pole placement and is built for the particular case that the original time-delay system has only a pure delayed state vector on its right hand side. For this method, the optimal gain such that the decay rate of the closed-loop system is maximized is also proposed. The effectiveness of the proposed approaches is illustrated by three linear time-delay systems that are open-loop unstable. © 2015 Elsevier B.V. All rights reserved.


Li Z.,Harbin Institute of Technology | Xue X.,Harbin Institute of Technology
Chaos | Year: 2010

This paper mainly studies synchronization between two coupled networks, which is called "outer synchronization." On the basis of Lyapunov function approach, we prove that for networks with balanced structure topology, outer synchronization can be asymptotically reached by using arbitrary coupling strength. We employ a concept which arises in studying the average-consensus problem. Some numerical examples are presented to illustrate the result in the end. The examples indicate that the coupling strength has real influence on the performance of outer synchronization for a short time. The numerical examples also show that the transverse Lyapunov exponent is independent of the value of coupling strength. © 2010 American Institute of Physics.


Li Q.,Harbin Institute of Technology | Hu J.,Harbin Institute of Technology
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

Terahertz Gabor in-line digital holographic system has the characteristics of high resolution and compact structure, and it has potential application prospects. The lateral resolution of the system is related to the recording distance, so the research on the effect of recording distance on imaging results in actual imaging system has important application values. By using self-made targets with resolutions of 0.4 mm and 0.6 mm, 2.52 THz Gabor in-line holography imaging experiments with different recording distances are carried out and digital reconstructions are realized by angular-spectrum representation. The reconstructed images are compared and analyzed, and experimental results are close to the theoretical calculation results of the lateral resolution changing with the recording distance.


Jingzhuo J.,Henan University of Science and Technology | Liu B.,Harbin Institute of Technology
IEEE Transactions on Industrial Electronics | Year: 2011

The operational efficiency of ultrasonic motor motion control systems is much lower than that of traditional electromagnetic motors, which badly restricts the application of ultrasonic motor in portable devices. Lower efficiency, robustness, and wear condition are the main problems of ultrasonic motor systems. This paper studies on the optimum efficiency control strategy of an ultrasonic motor system and selects the commercially used ultrasonic motor Shinsei USR60 as the experimental motor. To provide a basis for the optimum efficiency control, the control characteristic of system efficiency is studied first under speed closed-loop control condition. Then, a novel feedforward speed controller compounded with a pole-assignment controller is designed to compensate the disturbance caused by the efficiency optimization process. After that, the optimum efficiency control strategy with varying step length based on fuzzy reasoning is proposed. Experiments show that the proposed optimum control methods can greatly increase the operational efficiency of the ultrasonic motor system. © 2011 IEEE.


Yang T.,Harbin Institute of Technology | Zhang N.,Harbin Institute of Technology | Lang Y.,Harbin Institute of Technology | Sun K.,Harbin Institute of Technology
Electrochimica Acta | Year: 2011

Conductive carbon has been coated on the surface of LiNi 0.5Mn 1.5O 4 cathode material by the carbonization of sucrose for the purpose of improving the rate performance. The effect of carbon coating on the physical and electrochemical properties is discussed through the characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), cycling and rate tests. Results demonstrate that the carbon coating can greatly enhance the discharge capacity, rate capability and cycling stability of the LiNi 0.5Mn 1.5O 4 without degrading the spinel structure. The sample modified with 1 wt.% sucrose displays the best performance. A large capacity of 130 mAh g -1 at 1 C discharge rate with a high retention of 92% after 100 cycles and a stable 114 mAh g -1 at 5 C discharge rate can be delivered. The remarkably improved rate properties of the carbon-coated samples are due to the suppression of the solid electrolyte interfacial (SEI) layer development and faster kinetics of both the Li + diffusion and the charge transfer reaction. © 2011 Elsevier Ltd. All rights reserved.


Wu B.,Harbin Institute of Technology | Wang Z.,Harbin Institute of Technology | Wang Z.,University of Trento | Bursi O.S.,University of Trento
Earthquake Engineering and Structural Dynamics | Year: 2013

Real-time hybrid simulation represents a powerful technique capable of evaluating the structural dynamic performance by combining the physical simulation of a complex and rate-dependent portion of a structure with the numerical simulation of the remaining portion of the same structure. Initially, this paper shows how the stability of real-time hybrid simulation with time delay depends both on compensation techniques and on time integration methods. In particular, even when time delay is exactly known, some combinations of numerical integration and displacement prediction schemes may reduce the response stability with conventional compensation methods and lead to unconditional instability in the worst cases. Therefore, to deal with the inaccuracy of prediction and the uncertainty of delay estimation, a nearly exact compensation scheme is proposed, in which the displacement is compensated by means of an upper bound delay and the desired displacement is picked out by an optimal process. Finally, the advantages of the proposed scheme over conventional delay compensation techniques are shown through numerical simulation and actual tests. © 2013 John Wiley & Sons, Ltd.


Wang X.,Harbin Institute of Technology | Ni W.,Nanchang University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2012

In this paper, the leader-following formation problem of multirobot systems with switching interconnection topologies is considered. The robots are required to move in a formation with formation constrains described in terms of relative distances of the robots and the formation (as whole entity) is required to track the trajectory generated by an exosystem. The exosystem of the considered multirobot systems provides driving forces or environmental disturbance, whose dynamics is different from the dynamics of the robots. A systematic distributed design approach for the leader-following formation problem is proposed via dynamic output feedback with the help of canonical internal model. © 2012 IEEE.


Wang L.,Harbin Institute of Technology | Wang D.-L.,Harbin Institute of Technology
Electrochimica Acta | Year: 2011

MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 °C with MnO2-graphene oxide composites which are synthesized by a redox reaction between KMnO4 and graphene oxide. Powder X-ray diffraction (XRD) analyses and energy dispersive X-ray analyses (EDAX) show MnO2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. The electrochemical capacitance of MnOOH nanowire-graphene oxide composites prepared in 5% ammonia aqueous solution is 76 F g-1 at current density of 0.1 A g-1. Moreover, electrochemical impedance spectroscopy (EIS) suggests the electrochemical resistance of MnOOH nanowire-graphene oxide composites is reduced when hydrothermal reaction is conducted in ammonia aqueous solution. The relationship between the electrochemical capacitance and the structure of MnOOH nanowire-graphene oxide composites is characterized by cyclic voltammetry (CV) and field emission scanning electron microscopy (FESEM). The results indicate the electrochemical performance of MnOOH nanowire-graphene oxide composites strongly depends on their morphology. © 2011 Elsevier Ltd. All rights reserved.


Duan G.,Harbin Institute of Technology
Chinese Control Conference, CCC | Year: 2013

In this paper, a new type of high-order generalized Sylvester equations (GSEs) are investigated. Degrees of freedom is first investigated using the concept of F-coprimeness, and a complete general parametric solution in a neat explicit closed form is then established using a generalized matrix fraction right factorization. The primary feature of this solution is that the matrix F does not need to be in any canonical form, or may be even unknown a priori. The results provide great convenience to the computation and analysis of the solutions to this class of equations, and can perform important functions in many control systems analysis and design problems involving high-order dynamical systems. © 2013 TCCT, CAA.


Gao H.,Harbin Institute of Technology | Li X.,Harbin Institute of Technology
IEEE Transactions on Automatic Control | Year: 2011

This article researches the problem of finite frequency (FF) {H} \infty filtering for linear discrete-time state-delayed systems. The disturbance is assumed to reside in low/middle/high frequency ranges. To reduce the conservatism of the results, delay-partitioning idea is used to derive a new FF bounded real lemma (BRL). By applying the generalized Kalman-Yakubovich- Popov lemma, two equivalent approaches to the proof of the proposed FF BRL are given, respectively, starting from transfer function and Lyapunov-Krasovskii functional. A new FF {H} \infty filter design method is proposed in terms of solving a set of linear matrix inequalities. Finally, a numerical example clearly demonstrates the merits and effectiveness of the proposed method. © 2006 IEEE.


Ma J.,Harbin Institute of Technology
Geophysics | Year: 2013

We have developed a new algorithm for the reconstruction of seismic traces randomly missing from a uniform grid of a 3D seismic volume. Several algorithms have been developed for such reconstructions, based on properties of the seismic wavefields and on signal processing concepts, such as sparse signal representation in a transform domain. We have investigated a novel approach, originally introduced for noise removal, which is based on the premise that for suitable representation of the seismic data as matrices or tensors, the rank of the seismic data (computed by singular value decomposition) increases with noise or missing traces. Thus, we apply low-rank matrix completion (MC) with a designed texture-patch transformation to 3D seismic data reconstruction. Low-rank components capture geometrically meaningful structures in seismic data that encompass conventional local features such as events and dips. The low-rank MC is based on nuclear-norm minimization. An efficient L1-norm minimizing algorithm, named approximate message passing, is extended to use for a general nonconvex nuclear-norm minimization problem. A fast MC algorithm named low-rank matrix fitting (LMaFit), which avoids the computation of singular value decomposition, was also considered for the 3D reconstruction. Empirical studies on synthetic and real data have shown promising performance of the method, in comparison with traditional projection onto convex sets. © 2013 Society of Exploration Geophysicists.


Wang X.,Harbin Institute of Technology
International Journal of Control | Year: 2011

In this article, we consider the problem of optimal coverage of unknown environmental boundary using sensor networks. Since the boundary is unknown to all sensors, it is necessary for the sensors to find it first. We give a new distributed estimate policy by tracking a virtual agent using the sensor networks. Then we consider the problem of optimal coverage of the estimate boundary instead of the actual one. Moreover, an algorithm is given to deploy the sensors to the optimal configuration corresponding to the coverage problem considered in this article. © 2011 Taylor & Francis.


Dong C.,Harbin Institute of Technology | Li X.,Harbin Institute of Technology | Qi J.,Harbin Institute of Technology
Journal of Physical Chemistry C | Year: 2011

The first-principles quantum mechanical investigation on CdS quantum dots (QDs) adsorbed on anatase TiO2 nanotubes (TiO2NTs) in quantum dot-sensitized solar cells (QDSSCs) was performed using the density functional theory (DFT) approach. The geometry and electronic coupling between a CdS QD and the TiO2NT have been examined for the first time, together with a detailed discussion of interfacial electron transfer and electron transport models along the TiO2NT. It has been found that adsorbate states are introduced in the band gap of the TiO2NT upon the adsorption of a CdS QD on the TiO2NT surface, and an electron transfers from the sulfur atoms of a CdS QD to the conduction band of the TiO2NT upon adsorption of visible light. The unique TiO2NT structure offers a one-dimensional directional pathway for electron transport across the semiconductor substrate through titanium dx2-y2 and d z2 orbitals. Our work is of great benefit for understanding the charge separation process at the heterogeneous interface and the key factors to govern the electron transport efficiency in TiO2NTs. © 2011 American Chemical Society.


Zhao Y.,Harbin Institute of Technology | Zhao B.,CAS Institute of Biophysics
Frontiers in Bioscience - Elite | Year: 2012

Alzheimer's disease (AD) is the most common neurodegenerative disease that causes dementia in the elderly. As the aging population increases, the prevalence of AD has increased remarkably worldwide and AD has become one of the leading causes of disability and death among the elderly. A number of drugs have been approved for the treatment of AD; however, they produce only modest benefits and have a wide range of side effects. Therefore, extensive studies are underway to identify effective drugs that are free of undesirable side effects. As accumulating evidences have implicated oxidative stress in the initiation and progression of AD, the potential of using nature antioxidants for prevention and treatment of AD has attracted considerable attention. The present review discusses the involvement of oxidative stress in the pathogenesis of AD and the neuroprotective effects of natural antioxidants, such as Ginkgo biloba flavonoids, soybean isoflavones, theanine and nicotine in cell culture and AD transgenic animal models, specifically, their inhibition on Abeta-induced neurotoxicity and the underlined molecular mechanisms.


Liu S.,Harbin Institute of Technology | Zheng Z.,Harbin Institute of Technology | Li X.,Harbin Institute of Technology
Analytical and Bioanalytical Chemistry | Year: 2013

Public concern over pesticide residues has been increasing dramatically owing to the high toxicity and bioaccumulation effects of pesticides and the serious risks that they pose to the environment and human health. It is therefore crucial to monitor pesticide residues by using various analytical methods and techniques, especially highly sensitive, highly selective, simple, rapid, cost-effective, and portable ones. Biosensor strategies have become research hotspots and ideal candidates for pesticide detection, having such features as high sensitivity, fast response, robustness, low cost and miniaturization, as well as in situ and real-time monitoring. This review covers advances in the design and fabrication of biosensors for pesticide detection since 2005. Special emphasis is placed on the state-of-art selection of receptors, the use of different transduction techniques and fast screening strategies, and the application of various biosensors developed in food and environmental safety. Both advantages and drawbacks of these techniques are then summarized. Finally, challenges, strategies, and perspectives in further developing pesticide biosensors are also discussed. [Figure not available: see fulltext.] © 2012 Springer-Verlag.


Jiang Z.-Z.,Harbin Institute of Technology | Wang Z.-B.,Harbin Institute of Technology | Chu Y.-Y.,Harbin Institute of Technology | Gu D.-M.,Harbin Institute of Technology | Yin G.-P.,Harbin Institute of Technology
Energy and Environmental Science | Year: 2011

Pt/MWCNTs (Multi-walled carbon nanotubes, MWCNTs) and microcapsule Pt/MWCNTs-TiO2 catalysts have been prepared by microwave-assisted polyol process (MAPP). Electrochemical results show that microcapsule Pt/MWCNTs-TiO2 catalyst has higher activity and stability than Pt/MWCNTs due to more uniform dispersion and smaller size of Pt nanoparticles. Furthermore, carbon riveted microcapsule Pt/MWCNTs-TiO2 catalyst has been designed and synthesized on the basis of in situ carbonization of glucose. The physical characteristics such as XRD, TEM, HRTEM, STEM, and XPS have indicated that the anatase TiO2 indeed entered the inside of the MWCNTs and formed the microcapsule support of MWCNTs with TiO2. The accelerated potential cycling tests (APCT) indicate that the carbon riveted microcapsule Pt/MWCNTs-TiO2 catalyst with similar activity to microcapsule Pt/MWCNTs-TiO2 and Pt/C possesses 7.5-times as high stability as that of Pt/C and has 3-times as long life-span as that of carbon riveted Pt/TiO2-C reported in our previous work. The significantly enhanced stability for carbon riveted microcapsule Pt/MWCNTs-TiO2 catalyst is assignable to: (1) the inherently excellent mechanical resistance and stability of anatase TiO2 and MWCNTs in acidic and oxidative environments; (2) strong metal-support interaction between Pt nanoparticles and the microcapsule support; (3) the anchoring effect of the carbon layers formed during the carbon riveting process. © 2011 The Royal Society of Chemistry.


Xie Z.,Harbin Institute of Technology | Xu Y.,Harbin Institute of Technology
International Journal of Machine Learning and Cybernetics | Year: 2014

Uncertain data management and mining is becoming a hot topic in recent years. However, little attention has been paid to uncertain feature selection so far. In this paper, we introduce the sparse group least absolution shrinkage and selection operator (LASSO) technique to construct a feature selection algorithm for uncertain data. Each uncertain feature is represented with a probability density function. We take each feature as a group of values. Through analysis of the current four sparse feature selection methods, LASSO, elastic net, group LASSO and sparse group LASSO, the sparse group LASSO is introduced to select feature selection from uncertain data. The proposed algorithm can select not only the features between groups, but also the sub-features in groups. As the trained weights of feature groups are sparse, the groups of features with weight zero are removed. Experiments on nine UCI datasets show that feature selection for uncertain data can reduce the number of features and sub-features at the same time. Moreover it can produce comparable accuracy with all features. © 2013 Springer-Verlag Berlin Heidelberg.


Qian C.,Harbin Institute of Technology | Huang L.,Harbin Institute of Technology | So H.C.,City University of Hong Kong
IEEE Signal Processing Letters | Year: 2014

A novel pseudo-noise resampling (PR) based unitary root-MUSIC algorithm for direction-of-arrival (DOA) estimation is derived in this letter. Our solution is able to eliminate the abnormal DOA estimator called outlier and obtain an approximate outlier-free performance in the unitary root-MUSIC algorithm. In particular, we utilize a hypothesis test to detect the outlier. Meanwhile, a PR process is applied to form a DOA estimator bank and a corresponding root estimator bank. We propose a distance detection strategy which exploits the information contained in the estimated root estimator to help determine the final DOA estimates when all the DOA estimators fail to pass the reliability test. Furthermore, the proposed method is realized in terms of real-valued computations, leading to an efficient implementation. Simulations show that the improved MUSIC scheme can significantly improve the DOA resolution at low signal-to-noise ratios and small samples. © 2013 IEEE.


Li X.,Harbin Institute of Technology | Ng M.K.,Hong Kong Baptist University | Ye Y.,Harbin Institute of Technology
IEEE Transactions on Knowledge and Data Engineering | Year: 2014

The main aim of this paper is to develop a community discovery scheme in a multi-dimensional network for data mining applications. In online social media, networked data consists of multiple dimensions/entities such as users, tags, photos, comments, and stories. We are interested in finding a group of users who interact significantly on these media entities. In a co-citation network, we are interested in finding a group of authors who relate to other authors significantly on publication information in titles, abstracts, and keywords as multiple dimensions/entities in the network. The main contribution of this paper is to propose a framework (MultiComm)to identify a seed-based community in a multi-dimensional network by evaluating the affinity between two items in the same type of entity (same dimension)or different types of entities (different dimensions)from the network. Our idea is to calculate the probabilities of visiting each item in each dimension, and compare their values to generate communities from a set of seed items. In order to evaluate a high quality of generated communities by the proposed algorithm, we develop and study a local modularity measure of a community in a multi-dimensional network. Experiments based on synthetic and real-world data sets suggest that the proposed framework is able to find a community effectively. Experimental results have also shown that the performance of the proposed algorithm is better in accuracy than the other testing algorithms in finding communities in multi-dimensional networks. © 1989-2012 IEEE.


Hu J.,Harbin Institute of Technology | Wang Z.,Brunel University | Niu Y.,East China University of Science and Technology | Stergioulas L.K.,Brunel University
International Journal of Robust and Nonlinear Control | Year: 2012

In this paper, the H ∞ sliding mode observer (SMO) design problem is investigated for a class of nonlinear discrete time-delay systems. The nonlinear descriptions quantify the maximum possible derivations from a linear model, and the system states are allowed to be immeasurable. Attention is focused on the design of a discrete-time SMO such that the asymptotic stability as well as the H ∞ performance requirement of the error dynamics can be guaranteed in the presence of nonlinearities, time delay and external disturbances. Firstly, a discrete-time discontinuous switched term is proposed to make sure that the reaching condition holds. Then, by constructing a new Lyapunov-Krasovskii functional based on the idea of 'delay fractioning' and by introducing some appropriate free-weighting matrices, a sufficient condition is established to guarantee the desired performance of the error dynamics in the specified sliding mode surface by solving a minimization problem. Finally, an illustrative example is given to show the effectiveness of the designed SMO design scheme. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.


Qiu Y.,Harbin Institute of Technology | Ma Z.,Harbin Institute of Technology | Hu P.,Harbin Institute of Technology
Journal of Materials Chemistry A | Year: 2014

We report the facile synthesis of environmentally benign Au NPs/chitosan composites and magnetic Au NPs/chitosan/Fe3O4 composites without employing any toxic reductants or capping agents. Renewable natural chitosan not only functioned as supporting matrix, but also served as a reductant and stabilizer for the formation and dispersions of Au NPs. Fe 3O4 nanospheres were easily embedded into the chitosan matrix due to the strong complexation ability of chitosan with Fe 3O4, which originated from the sharing of the lone electron pairs from the nitrogen atom in amine with FeII or Fe III on the surface of Fe3O4. The as-prepared magnetic composites exhibited much higher activities, as well as more convenient magnetic recyclability than other supported Au NPs towards the reduction of 4-nitrophenol. From the practical point of view, apart from good performance of the reduction of nitro compounds, the biocompatibility and biodegradability of present Au NPs/chitosan/Fe3O4 composites promote the potential applications in the biochemical catalysis or therapy. This journal is © the Partner Organisations 2014.


Jiang Z.-Z.,Harbin Institute of Technology | Wang Z.-B.,Harbin Institute of Technology | Chu Y.-Y.,Harbin Institute of Technology | Gu D.-M.,Harbin Institute of Technology | Yin G.-P.,Harbin Institute of Technology
Energy and Environmental Science | Year: 2011

Highly active Pt/TiO2-C catalyst has been synthesized by a microwave-assisted polyol process. The obtained Pt/TiO2-C sample was characterized by XRD, EDAX, HRTEM, XPS, and electrochemical measurements. The results show that the Pt/TiO2-C catalyst possesses substantially enhanced stability and identical activity in comparison with Pt/C prepared by the same procedure. Furthermore, carbon riveted Pt/TiO2-C composite with a novel structure based on in situ carbonization of the glucose was designed and synthesized. The results of TEM and electrochemical measurements indicate that the carbon riveted Pt/TiO2-C catalyst has much greater stability than Pt/TiO2-C and Pt/C with similar activity. The significantly enhanced stability for carbon riveted Pt/TiO2-C catalyst is ascribed to: (1) the excellent stability of anatase TiO2; (2) the strong metal-support interaction between Pt and TiO2; (3) the anchoring effect of the carbon layers formed during the carbon riveting process. These findings indicate that carbon riveted Pt/TiO2-C is a promising catalyst for proton exchange membrane fuel cells which are under long term operation. © 2011 The Royal Society of Chemistry.


Zhang M.-H.,Northeast Forestry University | Zhang M.-H.,Harbin Institute of Technology | Li H.,Harbin Institute of Technology
Construction and Building Materials | Year: 2011

Pore structure and chloride permeability of concrete containing nano-particles (TiO2 and SiO2) for pavement are experimentally studied and compared with that of plain concrete, concrete containing polypropylene (PP) fibers and concrete containing both nano-TiO 2 and PP fibers. The test results indicate that the addition of nano-particles refines the pore structure of concrete and enhances the resistance to chloride penetration of concrete. The refined extent of pore structure and the enhanced extent of the resistance to chloride penetration of concrete are increased with the decreasing content of nano-particles. The pore structure and the resistance to chloride penetration of concrete containing nano-TiO2 are superior to that of concrete containing the same amount of nano-SiO2. However, for the concrete containing PP fibers, the pore structure is coarsened and the resistance to chloride penetration is reduced. The larger the content of PP fibers, the coarser the pore structure of concrete, and the lower the resistance to chloride penetration. For the concrete containing both nano-TiO2 and PP fibers, the pore structure is coarser and the resistance to chloride penetration is lower than that of concrete containing the same amount of PP fibers only. A hyperbolic relationship between chloride permeability and compressive strength of concrete is exhibited. There is an obvious linear relationship between chloride permeability and pore structure of concrete. © 2010 Elsevier Ltd. All rights reserved.


Qin S.,Harbin Institute of Technology | Xue X.,Harbin Institute of Technology | Wang P.,Harbin Institute of Technology
Information Sciences | Year: 2013

In this paper, we study the existence, uniqueness and stability of almost periodic solution for the class of delayed neural networks. The neural network considered in this paper employs the activation functions which are discontinuous monotone increasing and (possibly) unbounded. Under a new sufficient condition, we prove that the neural network has a unique almost periodic solution, which is globally exponentially stable. Moreover, the obtained conclusion is applied to prove the existence and stability of periodic solution (or equilibrium point) for delayed neural networks with periodic coefficients (or constant coefficients). We also give some illustrative numerical examples to show the effectiveness of our results. © 2012 Elsevier Inc. All rights reserved.


Fan L.,Harbin Institute of Technology | Zhang N.,Harbin Institute of Technology | Sun K.,Harbin Institute of Technology
Chemical Communications | Year: 2014

We reported fabrication of patterned flexible MECs using inkjet printing. The strategy can effectively simplify the fabrication process, thus reducing the cost. The obtained flexible MECs exhibited a very high specific capacitance of 6.4 mF cm-2, and revealed long-term cycling stability. This journal is © the Partner Organisations 2014.


Yu Y.,Harbin Institute of Technology | Chen G.,Harbin Institute of Technology | Wang Q.,Harbin Institute of Technology | Li Y.,Harbin Institute of Technology
Energy and Environmental Science | Year: 2011

Hierarchical ZnS-based microspheres with porous structures are successfully synthesized via a facile "one pot" route without using any templates or surfactants. These microspheres are aggregations composed of wurtzite/sphalerite heterostructure nanoflakes. Interestingly, due to the doping with In, the dipole field direction of ZnS-based nanoparticles changes. As a result, the formation of heterostructure nanoflakes are found to follow a lateral oriented attachment (LOA) mechanism and a subsequent phase transformation process rather than the oriented attachment (OA) mechanism reported in previous literatures. This discovery would provide a convenient method in constructing 2D anisotropic structures and might offer a new insight to the growth process of ZnS-based materials. Furthermore, photocatalytic activities for water splitting are investigated under visible-light irradiation (λ > 400 nm) and an enhanced photocatalytic activity (the initial rate for H 2 evolution is up to 3.7 mmol h -1 with a concentration of photocatalyst of 45 mg L -1) is achieved, attributable to the particular heterostructure of 2D nanoflakes, the porous structure of 3D microspheres and the large specific area of as-prepared photocatalyst powders. © 2011 The Royal Society of Chemistry.


Kar S.,Harbin Institute of Technology | Ho Y.K.,Academia Sinica, Taiwan
Computer Physics Communications | Year: 2011

We have investigated the Fe1,3 resonance states of positronium negative ion below the N=3, 4 and 5 Ps thresholds using highly correlated exponential wave functions. Resonance parameters (positions and widths) are extracted employing both the stabilization method and the complex-coordinate rotation method. In addition to many Feshbach resonances below the various Ps thresholds, we have identified two Fe1 shape resonances with one each lying above the N=3 and N=5 thresholds, respectively. We have also identified three Fe3 shape resonances with one lying above the N=3 threshold and two lying above N=4 threshold. The Fe1,3 shape resonances associated with N=3 Ps threshold and some other Feshbach resonances are reported for the first time in the literature. © 2010 Elsevier B.V. All rights reserved.


Sekulic D.P.,Harbin Institute of Technology | Sciubba E.,University of Rome La Sapienza | Moran M.J.,Ohio State University
Energy | Year: 2015

The purpose of this article is to assess the value of entransy for use in the thermal system engineering domain and in particular for design. The conclusion is that use of entransy is not recommended. This finding is in keeping with increasing uneasiness that has emerged recently in the technical literature about this concept. Throughout this article emphasis is on concise discussions of salient entransy aspects and the presentation is shaped to reach a broad technical audience. Accordingly, because secondary entransy aspects do not play a central role in reaching the above recommendation, they are considered only in passing or deferred. © 2014 Elsevier Ltd.


Zhu Q.,Harbin Institute of Technology | Pan Q.,Harbin Institute of Technology | Liu F.,Harbin Institute of Technology
Journal of Physical Chemistry C | Year: 2011

The development of a convenient method for the removal (or collection) of oils and organic solvents from water surface is of great significance for water environmental protection, especially for the cleanup of oil spillage on seawater. A major challenge is the fabrication of an oil absorber with high absorption capacity, low cost, scalable fabrication, high selectivity, and excellent recyclability. In this paper, we present a simple method for the removal and collection of oils and organic solvents from the surfaces of water based on superhydrophobic and superoleophilic sponges that were fabricated by solution-immersion processes. The as-prepared sponges fast and selectively absorbed various kinds of oils up to above 13 times the sponges' weight while completely repelling water through a combination of porous, superhydrophobic, and superoleophilic properties. More interesting, the absorbed oils were readily collected by a simple mechanical squeezing process, and the recovered sponges could be reused in oil-water separation for many cycles while still keeping high separation efficiency. The findings presented in this study might provide a fast and simple approach for the cleanup of oils and organic solvents on water surfaces. © 2011 American Chemical Society.


Kar S.,Harbin Institute of Technology | Ho Y.K.,Academia Sinica, Taiwan
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We have searched for S-wave shape resonances in the Ps - system. The calculations are carried out in the framework of the complex-coordinate rotation method using both Hylleraas-type wave functions involving powers of interparticle coordinates, and the exponential correlated wave functions. We have located an S-wave shape resonance lying above the Ps (N = 2) threshold. By changing the mass of the positively charged particle from one unit of the electron mass to infinitely heavy, we have traced this resonance pole from Ps - to H -. Results for the shape resonance in H - are comparable with the available results in the literature. © 2012 American Physical Society.


Kar S.,Harbin Institute of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

In the present study, we investigate the effect of Debye-Hückel potentials on the frequency-dependent dipole polarizability of the helium atom using highly correlated wave functions within the framework of the pseudostate summation technique. The dynamic dipole polarizability of He (1s2 1S) as a function of the scaled number density of the plasma electrons for arbitrary plasma temperature is presented. Screening effects on the resonance frequencies are also presented. In a free-atomic system, our calculated results are in agreement with the available theoretical and experimental predictions. © 2012 American Physical Society.


Zhao F.,Harbin Institute of Technology | Huang Y.,Harbin Institute of Technology
Materials Letters | Year: 2011

High density carbon fiber fabric was modified by using γ-ray irradiation grafting technology in ammonia and gaseous triethylenetetramine. Atomic force microscopy and X-ray photoelectron spectroscopy were performed to characterize the modified carbon fibers. The results showed that the irradiation grafting was much more uniform throughout the thickness of the fabric compared with the traditional commercial electrochemical treatment and the nitrogen-containing functional groups were significantly increased. The single fiber pull-out tests indicated that the interfacial strength of the resulting composites had dramatic increases and the single fiber tensile strength measurements showed that the fiber strength did not have any discernable decrease. © 2011 Elsevier B.V. All rights reserved.


Chang Y.,University of Florida | Ries R.J.,University of Florida | Wang Y.,Harbin Institute of Technology
Energy Policy | Year: 2011

With rapid social development and large-scale construction of infrastructure in China, construction projects have become one of the driving forces for the national economy, whose energy consumption, environmental emissions, and social impacts are significant. To completely understand the role of construction projects in Chinese society, this study developed input-output life-cycle assessment models based on 2002, 2005, and 2007 economic benchmarks. Inventory indicators included 10 types of energy, 7 kinds of environmental emissions, and 7 kinds of social impacts. Results show that embodied energy of construction projects in China accounts for 25-30% of total energy consumption; embodied SO 2 emissions are being controlled, and the intensities of embodied NO x and CO 2 have been reduced. However, given that the construction sector related employment is 17% of the total employment in China, the accidents and fatalities related to the construction sector are significant and represent approximately 50% of the national total. The embodied human and capital investments in science and technology (ST) increased from 2002 to 2007. The embodied full time equivalent (FTE) of each ST person also increased while the personal ST funding and intramural expenditures decreased. This might result from the time lag between RD activities and large-scale implementation. © 2011.


Lu S.,Duke University | Lu S.,Harbin Institute of Technology | Cheng Y.,Duke University | Wu X.,Duke University | And 2 more authors.
Nano Letters | Year: 2013

Long-term instability of Li-S batteries is one of their major disadvantages compare to other secondary batteries. The reasons for the instability include dissolution of polysulfide intermediates and mechanical instability of the electrode film caused by volume changes during charging/discharging cycles. In this paper, we report a novel graphene-sulfur-carbon nanofibers (G-S-CNFs) multilayer and coaxial nanocomposite for the cathode of Li-S batteries with increased capacity and significantly improved long-cycle stability. Electrodes made with such nanocomposites were able to deliver a reversible capacity of 694 mA h g-1 at 0.1C and 313 mA h g-1 at 2C, which are both substantially higher than electrodes assembled without graphene wrapping. More importantly, the long-cycle stability was significantly improved by graphene wrapping. The cathode made with G-S-CNFs with a initial capacity of 745 mA h g-1 was able to maintain ∼273 mA h g-1 even after 1500 charge-discharge cycles at a high rate of 1C, representing an extremely low decay rate (0.043% per cycle after 1500 cycles). In contrast, the capacity of an electrode assembled without graphene wrapping decayed dramatically with a 10 times high rate (∼0.40% per cycle after 200 cycles). These results demonstrate that the coaxial nanocomposites are of great potential as the cathode for high-rate rechargeable Li-S batteries. Such improved rate capability and cycle stability could be attributed to the unique coaxial architecture of the nanocomposite, in which the contributions from graphene and CNFs enable electrodes with improved electrical conductivity, better ability to trap soluble the polysulfides intermediate and accommodate volume expansion/shrinkage of sulfur during repeated charge/discharge cycles. © 2013 American Chemical Society.


Sun C.-L.,Taiyuan University of Science and Technology | Zeng J.-C.,Taiyuan University of Science and Technology | Pan J.-S.,Harbin Institute of Technology | Pan J.-S.,National Kaohsiung University of Applied Sciences
Information Sciences | Year: 2011

Increasing attention is being paid to solve constrained optimization problems (COP) frequently encountered in real-world applications. In this paper, an improved vector particle swarm optimization (IVPSO) algorithm is proposed to solve COPs. The constraint-handling technique is based on the simple constraint-preserving method. Velocity and position of each particle, as well as the corresponding changes, are all expressed as vectors in order to present the optimization procedure in a more intuitively comprehensible manner. The NVPSO algorithm [30], which uses one-dimensional search approaches to find a new feasible position on the flying trajectory of the particle when it escapes from the feasible region, has been proposed to solve COP. Experimental results showed that searching only on the flying trajectory for a feasible position influenced the diversity of the swarm and thus reduced the global search capability of the NVPSO algorithm. In order to avoid neglecting any worthy position in the feasible region and improve the optimization efficiency, a multi-dimensional search algorithm is proposed to search within a local region for a new feasible position. The local region is composed of all dimensions of the escaped particle's parent and the current positions. Obviously, the flying trajectory of the particle is also included in this local region. The new position is not only present in the feasible region but also has a better fitness value in this local region. The performance of IVPSO is tested on 13 well-known benchmark functions. Experimental results prove that the proposed IVPSO algorithm is simple, competitive and stable. © 2010 Elsevier Inc. All rights reserved.


Li J.-B.,Harbin Institute of Technology
ICIC Express Letters | Year: 2010

A novel Nonparametric Kernel Discriminant Analysis (NKDA) based facialfeature extraction method insensitive to varying illumination is proposed forface recognition. Theoretical analysis on the recently proposed, NonparametricDiscriminant Analysis (NDA) (IEEE Trans. PAMI, 2009) shows that NDA has itslimitations on extracting the nonlinear features owing to the high nonlinearand, complex distribution of facial images under varying lighting conditions. Inorder to improve NDA for face recognition, NKDA is proposed, in this letterthrough improving NDA with kernel trick. Experimental results show that it isfeasible to enhance the recognition performance of NDA with kernel method.ICIC International © 2010.


Gu B.,Arizona State University | Ye Q.,Harbin Institute of Technology
Production and Operations Management | Year: 2014

With the growing influence of online social media, firms increasingly take an active role in interacting with consumers in social media. For many firms, their first step in online social media is management responses, where the management responds to customers' comments about the firm or its products and services. In this article, we measure the impact of management responses on customer satisfaction using data retrieved from a major online travel agency in China. Applying a panel data model that controls for regression toward the mean and heterogeneity in individual preference for hotels, we find that online management responses are highly effective among low satisfaction customers but have limited influence on other customers. Moreover, we show that the public nature of online management responses introduces a new dynamic among customers. Although online management responses increase future satisfaction of the complaining customers who receive the responses, they decrease future satisfaction of complaining customers who observe but do not receive management responses. The result is consistent with the peer-induced fairness theory. © 2013 Production and Operations Management Society.


Hao S.,Harbin Institute of Technology | Chen G.,Harbin Institute of Technology | Chen G.,State University of New York at Buffalo | Yang C.,Harbin Institute of Technology
Theranostics | Year: 2013

Optical sensing plays an important role in theranostics due to its capability to detect hint bio-chemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit. © Ivyspring International Publisher.


Xue X.,Harbin Institute of Technology | Li Z.,Harbin Institute of Technology
IEEE Transactions on Automatic Control | Year: 2010

This note studies the asymptotic stability of switched positive linear discrete systems whose subsystems are (sp) matrices. Such a matrix is the character of a kind of asymptotically stable linear systems and it is very easy to test. A new definition of (sp) matrix is given by means of graph theory. Based on an approaching using partially ordered semigroups and Lie algebras, we present several new criteria for asymptotic stability. We also derive an algebraic condition and discuss a kind of higher order difference equation. Our results have a robustness property to some extent. © 2010 IEEE.


Feng Y.,Harbin Institute of Technology | Feng Y.,Chongqing University | Han F.,RMIT University | Yu X.,RMIT University
Automatica | Year: 2014

In conventional sliding-mode control systems, the sliding-mode motion is of reduced order. Two main problems hindering the application of the sliding-mode control are the singularity in terminal sliding-mode control systems and the chattering in both the conventional linear sliding-mode and the terminal sliding-mode control systems. This paper proposes a chattering-free full-order terminal-sliding-mode control scheme. Since the derivatives of terms with fractional powers do not appear in the control law, the control singularities are avoided. A continuous control strategy is developed to achieve the chattering free sliding-mode control. During the ideal sliding-mode motion, the systems behave as a desirable full-order dynamics rather than a desirable reduced-order dynamics. A systematic design method of full-order sliding-mode control for nonlinear systems is presented, which allows both the chattering and singularity problems to be resolved. Simulations validate the proposed chattering free full-order sliding-mode control. © 2014 Elsevier Ltd. All rights reserved.


Zou Z.,Harbin Institute of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

In this paper, we propose bitruss, a new notion of a dense subgraph of a bipartite graph. Specifically, the k-bitruss of a bipartite graph is the largest edge-induced subgraph H such that every edge of H is contained in at least k rectangles within H. The bitruss decomposition of a bipartite graph is the set of all nonempty k-bitrusses of the bipartite graph for k ≥ 0. In this paper, we show that the bitruss decomposition of a bipartite graph have three important properties. First, the bitruss decomposition is unique. Second, the bitruss decomposition is hierarchical, that is, the (k+1)-bitruss is a subgraph of the k-bitruss for all k ≥ 0. Third, the bitruss decomposition can be computed in polynomial time. These three interesting properties make bitruss a promising notion of dense bipartite subgraphs. © Springer International Publishing Switzerland 2016.


Xu L.,Harbin Institute of Technology | Yang L.,Harbin Institute of Technology | Lei S.,Harbin Institute of Technology
Nanoscale | Year: 2012

In this review, we give a brief account on the recent scanning tunneling microscopy investigation of interfacial structures and properties of π-conjugated semiconducting oligomers and polymers, either at the solid-air (including solid-vacuum) or at the solid-liquid interface. The structural aspects of the self-assembly of both oligomers and polymers are highlighted. Conjugated oligomers can form well ordered supramolecular assemblies either at the air-solid or liquid-solid interface, thanks to the relatively high mobility and structural uniformity in comparison with polymers. The backbone structure, substitution of side chains and functional groups can affect the assembling behavior significantly, which offers the opportunity to tune the supramolecular structure of these conjugated oligomers at the interface. For conjugated polymers, the large molecular weight limits the mobility on the surface and the distribution in size also prevents the formation of long range ordered supramolecular assembly. The submolecular resolution obtained on the assembling monolayers enables a detailed investigation of the chain folding at the interface, both the structural details and the effect on electronic properties. Besides the ability in studying the assembling structures at the interfaces, STM also provides a reasonable way to evaluate the distribution of the molecular weight of conjugated polymers by statistic of the contour length of the adsorbed polymer chains. Both conjugated oligomers and polymers can form composite assemblies with other materials. The ordered assembly of oligomers can act as a template to controllably disperse other molecules such as coronene or fullerene. These investigations open a new avenue to fine tune the assembling structure at the interface and in turn the properties of the composite materials. To summarize scanning tunneling microscopy has demonstrated its surprising ability in the investigation of the assembling structures and properties of conjugated oligomers and polymers. The information obtained could benefit the understanding of the elements affecting the film morphology and helps the optimization of device performance. This journal is © 2012 The Royal Society of Chemistry.


Liu J.,Harbin Institute of Technology | Liu W.,Harbin Institute of Technology | Xue W.,Harbin Institute of Technology
Materials and Design | Year: 2013

Metal-plastic sandwich sheet has received increasing attention in aeronautical, automotive, marine and civil engineering industries due to its lower density, higher specific flexural stiffness, better dent resistance, better sound and vibration damping characteristics. In the present study, an AA5052/polyethylene/AA5052 sandwich sheet is developed and its formabilities are investigated. A numerical simulation method based on the Gurson-Tvergaard-Needleman (GTN) damage model is used for simulating the forming process of sandwich sheet, in which the interface conditions between skin sheet and core materials are considered by using the cohesive zone model (CZM). The rigid punch dome tests and the Nakazima forming tests are carried out to build the forming limit diagrams (FLDs) of sandwich sheet. A strain history method is applied to determine the limited strain. Comparisons between predictions and experimental results validate the used numerical simulation method. Finally, the influences of polyethylene's thickness on the formabilities of sandwich sheet are analyzed. Research results show that: AA5052/polyethylene/AA5052 sandwich sheet has a better formability than monolithic AA5052 sheet and the formability of AA5052/polyethylene/AA5052 sandwich sheet increases with increasing the thickness of polyethylene core layer. © 2012 Elsevier Ltd.


Lai X.,CAS Institute of Process Engineering | Halpert J.E.,CAS Institute of Process Engineering | Wang D.,CAS Institute of Process Engineering | Wang D.,Harbin Institute of Technology
Energy and Environmental Science | Year: 2012

Hollow micro-/nano-structured materials are now playing an important role in cutting edge innovations for energy conversion and storage technologies such as solar cells, fuel cells, lithium ion batteries and super capacitors. These materials show great promise in addressing growing environmental concerns for cleaner power sources at a time of increasing global demand for energy. In this perspective, we show that complex multi-shelled micro-/nano-materials show significant material advantages in many applications over conventional simple hollow structures. We also summarize the vast array of synthetic strategies used to create multi-shelled hollow structures, and discuss the possible application of these novel materials for power generation and storage. Finally, the emergent challenges and future developments of multi-shelled hollow structures are further discussed. © The Royal Society of Chemistry 2012.


Shi X.,Montana State University | Xie N.,Harbin Institute of Technology | Fortune K.,Montana State University | Gong J.,Wuhan Polytechnic University
Construction and Building Materials | Year: 2012

Concrete is a unique composite material that is porous and highly heterogeneous. The durability of steel reinforced concrete in chloride environments is of great interest to design engineers, infrastructure owners and maintainers, and researchers. This review reports recent advances in the knowledge base relevant to the durability of steel reinforced concrete in chloride environments, including: the role of mineral admixtures in concrete durability, the methods of measuring the chloride ingress into concrete, the challenges in assessing concrete durability from its chloride diffusivity, and the service life modeling of reinforced concrete in chloride-laden environments. It concludes with a look to the future, including research needs to be addressed. © 2011 Elsevier Ltd. All rights reserved.


Lin X.,Harbin Institute of Technology | He Q.,Harbin Institute of Technology | Li J.,CAS Beijing National Laboratory for Molecular
Chemical Society Reviews | Year: 2012

Confined surface gradients consisting of polymer brushes have great potential in various applications such as microfluidic devices, sensors, and biophysical research. Among the available fabrication approaches, nanolithographies combined with self-assembled monolayers and surface-initiated polymerization have became powerful tools to engineer confined gradients or predefined complex gradients on the nanometre size. In this tutorial review, we mainly highlight the research progress of the fabrication of confined polymer brush gradients by using electron beam, laser, and probe-based nanolithographies and the physical base for these approaches. The application of these polymer brush gradients in biomedical research is also addressed. © The Royal Society of Chemistry 2012.


Liu H.J.,Harbin Institute of Technology | Feng X.L.,Harbin Institute of Technology
Materials and Design | Year: 2013

The effect of post-processing heat treatment on the microstructure and microhardness of water-submerged friction stir processed 2219-T6 aluminum alloy was investigated. The microstructure was characterized using optical microscopy, scanning electron microscopy, and transmission electron microscopy. Two types of heat treatments, aging treatment and solutionizing followed by water quenching and aging treatment, were applied to the processed samples. The solutionizing followed by water quenching and aging treatment resulted in the abnormal grain growth in the stirred zone as well as the homogenous microhardness increase. The post-processing aging treated samples showed coarsened equilibrium precipitates and no re-precipitation, which led to the further decrease of the microhardness. © 2012 Elsevier Ltd.


Fu G.,Harbin Institute of Technology | Liu W.,Harbin Institute of Technology | Feng S.,Harbin Institute of Technology | Yue X.,Harbin Institute of Technology
Chemical Communications | Year: 2012

Herein, prussian blue nanoparticles, an ancient dye, were explored as a new generation of near-infrared laser-driven photothermal ablation agents for cancer therapy alternative to traditional agents due to their good photothermal efficiency and high photothermal stability but low cost and particularly clinically approved biosafety. This journal is © The Royal Society of Chemistry 2012.


Dong H.,Harbin Institute of Technology | Dong H.,Northeast Petroleum University | Wang Z.,Brunel University | Lam J.,University of Hong Kong | Gao H.,Harbin Institute of Technology
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2012

This paper is concerned with the network-based robust fault detection problem for a class of uncertain discrete-time Takagi-Sugeno fuzzy systems with stochastic mixed time delays and successive packet dropouts. The mixed time delays comprise both the multiple discrete time delays and the infinite distributed delays. A sequence of stochastic variables is introduced to govern the random occurrences of the discrete time delays, distributed time delays, and successive packet dropouts, where all the stochastic variables are mutually independent but obey the Bernoulli distribution. The main purpose of this paper is to design a fuzzy fault detection filter such that the overall fault detection dynamics is exponentially stable in the mean square and, at the same time, the error between the residual signal and the fault signal is made as small as possible. Sufficient conditions are first established via intensive stochastic analysis for the existence of the desired fuzzy fault detection filters, and then, the corresponding solvability conditions for the desired filter gains are established. In addition, the optimal performance index for the addressed robust fuzzy fault detection problem is obtained by solving an auxiliary convex optimization problem. An illustrative example is provided to show the usefulness and effectiveness of the proposed design method. © 2006 IEEE.


Wu L.,Harbin Institute of Technology | Feng Z.,University of Hong Kong | Zheng W.X.,University of Western Sydney
IEEE Transactions on Neural Networks | Year: 2010

This paper is concerned with the problem of exponential stability analysis of continuous-time switched delayed neural networks. By using the average dwell time approach together with the piecewise Lyapunov function technique and by combining a novel Lyapunov-Krasovskii functional, which benefits from the delay partitioning method, with the free-weighting matrix technique, sufficient conditions are proposed to guarantee the exponential stability for the switched neural networks with constant and time-varying delays, respectively. Moreover, the decay estimates are explicitly given. The results reported in this paper not only depend upon the delay but also depend upon the partitioning, which aims at reducing the conservatism. Numerical examples are presented to demonstrate the usefulness of the derived theoretical results. © 2006 IEEE.


Shi L.,Harbin Institute of Technology | Xia W.,Harbin Institute of Technology
Chemical Society Reviews | Year: 2012

The functionalization of C-H bonds and the visible light photoredox catalysis represent two prominent challenges in organic chemistry. In this regard, the combination of visible-light catalysis and C-H bond functionalization adjacent to a tertiary amine has been successfully developed in the past three years. In this tutorial review, we aim to give a brief overview of this issue and state the main results obtained in the reactions. This journal is © The Royal Society of Chemistry 2012.


Shi L.,Harbin University of Science and Technology | Shen Q.,Harbin University of Science and Technology | Qiu Z.,Harbin Institute of Technology
Journal of Luminescence | Year: 2014

Er-doped and Er/Yb-codoped LiTaO3 polycrystals were synthesized by the solid-state reaction method at 1200 C. The structural properties of Er/Yb:LiTaO3 polycrystals were confirmed by the X-ray diffraction patterns. The upconversion emission spectra of Er:LiTaO3 polycrystals showed that the intensities of the green and red upconversion emissions enhanced with the increasing concentration of Er3+ ions. The increased intensity ratio of the red to green emission was attributed to the two cross relaxation processes 4S3/2+4I 15/2→4I9/2+4I13/2 and 2H11/2+4I11/2→ 4F9/2+4F9/2. Upconversion emission tuning from green to red was observed in Er/Yb:LiTaO3 polycrystals under 980 nm excitation. It was proposed that the efficient cross relaxation process (4F7/2+4I11/2→ 4F9/2+4F9/2) and the energy back transfer (4S3/2 Er+2F7/2 Yb→4I13/2 Er+2F5/2 Yb) contribute the increased intensity ratio of the red to green emission in Er/Yb:LiTaO3 polycrystals. Studies on the pump power dependence indicated that the green emitting 4S3/2/2H 11/2 states and the red emitting 4F9/2 state were populated via the energy transfer assisted UC process besides a two-photon process in Er/Yb:LiTaO3 polycrystals. © 2013 Elsevier B.V.


Yu Z.,Harbin Institute of Technology
International Journal of Computer Mathematics | Year: 2013

The aim of this paper is to improve some results obtained in our earlier paper [Z. Yu and M. Liu, Almost surely asymptotic stability of numerical solutions for neutral stochastic delay differential equations, Discrete Dyn. Nat. Soc. 2011 (2011), article id 217672, 11 p., doi:10.1155/2011/217672]. In this paper, we establish an improved theorem and show that the backward Euler method can reproduce the property of almost sure and mean square exponential stability of exact solutions to neutral stochastic delay differential equations. To obtain the desired result, some new proof techniques are adopted. © 2013 Copyright Taylor and Francis Group, LLC.


Bai S.,Harbin Institute of Technology
Sensors (Basel, Switzerland) | Year: 2014

Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc.


Huang X.,Harbin Institute of Technology | Li W.,Harbin Institute of Technology | Zhang D.,Harbin Institute of Technology | Qin W.,Harbin Institute of Technology
Bioresource Technology | Year: 2013

Ammonium removal from source water is usually inhibited by insufficient carbon sources and low temperature in Northeastern China. A strain Y16 was isolated from oligotrophic niche and was identified as Acinetobacter sp. Y16. It demonstrated excellent capability for ammonium removal at 2. °C, and simultaneously produced nitrogen gas as the end product. About 66% of ammonium was removed after 36. h of incubation. Only trace accumulation of nitrate was observed during the process. The utilization of nitrite and nitrate as well as the existence of napA gene further proved the aerobic denitrification ability of strain Y16. Sodium acetate was the most favorable carbon source for ammonium oxidation by strain Y16. High rotation speed was beneficial for ammonium oxidation. Furthermore, strain Y16 could efficiently remove ammonium at low C/N ratio and low temperature conditions, which was advantageous for nitrogen removal from source water under cold temperatures. © 2013 Elsevier Ltd.


Wang K.F.,Harbin Institute of Technology | Wang B.L.,Harbin Institute of Technology
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2011

The vibration behaviors of simply supported Kirchhoff and Mindlin nanoscale plates with consideration of surface effects are studied using the nonlocal elastic theory. The motion equations of the nanoplates are obtained and the closed form solutions for natural frequency are established using Naviers approach. According to the analysis, the influences of surface energy and nonlocal effect on natural frequency of the nanoplates are very significant. The surface energy increases the natural frequency but the nonlocal parameter decreases the natural frequency. The influence of nonlocal effect becomes increasingly pronounced for higher order vibration modes. On the contrast, the effect of surface energy is important at lower frequencies. © 2011 Elsevier B.V. All rights reserved.


Feng W.,Harbin Institute of Technology | Zheng W.,Harbin Institute of Technology | Cao W.,Harbin Institute of Technology | Cao W.,Pennsylvania State University | Hu P.,Harbin Institute of Technology
Advanced Materials | Year: 2014

The back gate multilayer InSe FETs exhibit ultrahigh carrier mobilities, surpassing all the reported layer semiconductor based electronics with the same device configuration, which is achieved by the suppression of the carrier scattering from interfacial coulomb impurities or surface polar phonons at the interface of an oxidized dielectric substrate. The room-temperature mobilities of multilayer InSe transistors increase from 64 cm2 V-1 s-1 to 1055 cm2 V-1 s-1 using a bilayer dielectric of poly-(methyl methacrylate) (PMMA)/Al2 O3. The transistors also have high current on/off ratios of 1 × 108, low standby power dissipation, and robust current saturation in a broad voltage range. (Figured Presented). © 2014 Wiley-VCH Verlag GmbH & Co. KGaA.


Zhao Y.,Harbin Institute of Technology | Gao H.,Harbin Institute of Technology | Lam J.,University of Hong Kong
Information Sciences | Year: 2011

This paper investigates the problem of H∞ filtering for continuous Takagi-Sugeno (T-S) fuzzy systems with an interval time-varying delay in the state. Based on the delay partitioning idea, a new approach is proposed for solving this problem, which can achieve much less conservative feasibility conditions. The attention is focused on the design of an H∞ filter via the parallel distributed compensation scheme such that the filter error system is asymptotically stable and the H∞ attenuation level from disturbance to estimation error is below a prescribed scalar. The constructed Lyapunov-Krasovskii functional, by applying the delay partitioning method, can potentially guarantee the obtained delay-dependent conditions to be less conservative than those in the literature. The obtained results are formulated in the form of linear matrix inequalities (LMIs), which can be readily solved via standard numerical software. Finally, an example is illustrated to show the reduction in conservatism of the proposed filter design method. © 2011 Elsevier Inc. All rights reserved.


Yin S.,Harbin Institute of Technology | Wu L.,Harbin Institute of Technology | Nutt S.,University of Southern California
Composite Structures | Year: 2013

Hierarchical composite pyramidal lattice (CPL) cores with foam-core sandwich struts were designed, and two stacking patterns were fabricated and tested in out-of-plane compression. Analytical expressions for five possible failure modes were derived considering not only stretching and bending deformation but also shear deformation of struts. Core shear failure was absent from collapse mechanism maps for both Patterns-I and II CPL cores. Optimized Pattern-I hierarchical CPL cores were more efficient than Pattern-II cores. The following comparison with almost all competing composite sandwich cores revealed that the hierarchical CPL structures here, the assembly of both stretch- and bend-dominated constructions, could perform among the most efficient sandwich cores. Meanwhile, the construction concept can also enable multifunctionality by judicious selection of strut core materials without compromising structural efficiency. © 2012 Elsevier Ltd.


Zhao X.-D.,Harbin Institute of Technology | Zeng Q.-S.,Harbin Institute of Technology
International Journal of Automation and Computing | Year: 2010

This paper proposes improved stochastic stability conditions for Markovian jump systems with interval time-varying delays. In terms of linear matrix inequalities (LMIs), less conservative delay-range-dependent stability conditions for Markovian jump systems are proposed by constructing a different Lyapunov-Krasovskii function. The resulting criteria have advantages over some previous ones in that they involve fewer matrix variables but have less conservatism. Numerical examples are provided to demonstrate the efficiency and reduced conservatism of the results in this paper. © 2010 Institute of Automation, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.


Zhao X.,Harbin Institute of Technology | Zeng Q.,Harbin Institute of Technology
Journal of the Franklin Institute | Year: 2010

This paper deals with the problems of robust delay-dependent stability and H∞ analysis for Markovian jump linear systems with norm-bounded parameter uncertainties and time-varying delays. In terms of linear matrix inequalities, an improved delay-range-dependent stability condition for Markovian jump systems is proposed by constructing a novel LyapunovKrasovskii functional with the idea of partitioning the time delay, and a sufficient condition is derived from the H∞ performance. Numerical examples are provided to demonstrate efficiency and reduced conservatism of the results in this paper. © 2010 The Franklin Institute.


Ma K.,Harbin Institute of Technology | Khalil H.K.,Michigan State University
IEEE Transactions on Automatic Control | Year: 2010

In [1] , Serrani, Isidori, and Marconi design an output feedback controller that achieves semiglobal output regulation for a class of minimum phase nonlinear systems. The controller has three components: an internal model to ensure asymptotic regulation, a high-gain partial state feedback controller to stabilize the augmented system of the plant and internal model, and a high-gain observer to implement the partial state feedback. In this note we show a property of the transient response of this controller. We consider an alternate controller that shares with the controller of [1] the structure of high-gain partial state feedback and high-gain observer, but without internal model. Such controller can only achieve practical regulation. We show that when the controller and observer gains are large enough, the trajectories under the two controllers will be close to each other. Hence, the transient response of the controller of is not degraded by the inclusion of internal model. A similar transient response property is shown by Seshagiri and Khalil for the conditional servocompensator. Similarities and differences between the two designs are pointed out. © 2006 IEEE.


Zhou H.,Harbin Institute of Technology | Liu Z.,Harbin Institute of Technology
IEEE Transactions on Vehicular Technology | Year: 2010

A yaw stability-control system is designed to make vehicle yaw rate follow its reference in this paper. Based on the sliding-mode and backstepping approach, the cascade control system is combined with a tire/road force observer and a yaw stability controller. The tire/road force observer considers wheel longitudinal force as an unknown input to wheel dynamics and uses the sliding-mode method to reconstruct it. The yaw stability controller is designed based on a model about vehicle yaw rate, and the wheel dynamics were chosen according to the vehicle situation. In backstepping framework, brake torque is calculated in two steps. The performance is evaluated in a critical cornering maneuver situation through simulation with a multibody vehicle dynamics software, and the result indicates that the proposed controller can significantly maintain vehicle stability for active safety. © 2006 IEEE.


Hu S.-P.,Harbin Institute of Technology | Xu C.-Y.,Harbin Institute of Technology | Zhen L.,Harbin Institute of Technology
Materials Letters | Year: 2013

Bi2WO6 hollow structures consisting of nanoparticles with diameters of 10-20 nm were synthesized by a facile and reproducible solvothermal method in the presence of ethylene glycol. The obtained Bi 2WO6 hollow structures exhibit higher photocatalytic activity towards the degradation of Rhodamine B (RhB) under visible-light irradiation, up to 99% within 40 min, which was much higher than P25-TiO 2. The enhanced photocatalytic performance could be attributed to their tiny building blocks as well as high BET surface areas (65.04 m 2 g-1). The obtained Bi2WO6 hollow structures are chemically stable, and the efficiency remained almost the same after recycled five times, suggesting that Bi2WO6 hollow structures are promising visible-light photocatalyst for practical applications. © 2012 Elsevier B.V.


Zhao X.,Harbin Institute of Technology | Zeng Q.,Harbin Institute of Technology
International Journal of Adaptive Control and Signal Processing | Year: 2010

This paper investigates the problems of H∞ disturbance attenuation and H∞ filtering for Markovian jump systems with interval time-varying delays. In terms of linear matrix inequalities, a less conservative delay-range-dependent H∞ performance condition for Markovian jump systems is proposed by constructing a different Lyapunov-Krasovskii functional. The resulting criterion has advantages over some previous ones in that they involve fewer matrix variables, but has less conservatism. Based on this new condition, an improved H∞ filtering algorithm is developed. Numerical examples are provided to demonstrate the efficiency and reduced conservatism of the results in this paper. Copyright © 2009 John Wiley & Sons, Ltd.


Su X.,Harbin Institute of Technology | Tian Y.,Harbin Institute of Technology | Li H.,Harbin Institute of Technology | Wang C.,Harbin Institute of Technology
Bioresource Technology | Year: 2013

In order to obtain a better understanding of the relationship between sludge characteristics and the cake formation in membrane bioreactors (MBRs), the characteristics of cake sludge and bulk sludge were investigated and compared. Based on the extended Derjaguin-Landau-Verwey-Overbeek (extended DLVO) theory, the aggregation abilities of cake sludge and bulk sludge were also evaluated. It is observed that cake sludge showed worse aggregation ability than bulk sludge. Further analysis indicated that small flocs, colloids, loosely bound extracellular polymeric substances (LB-EPS), hydrophobicity and negative charge played important role in cake formation and sludge aggregation. Cake sludge with worse aggregation had higher distribution spread index (DSI), more colloids and LB-EPS, higher hydrophobicity and more negative charge. The results indicated that sludge aggregation might reflect membrane fouling potential of sludge. © 2012 Elsevier Ltd.


Sun J.,Harbin Institute of Technology | Chen G.,Harbin Institute of Technology | Wu J.,Harbin Institute of Technology | Dong H.,Harbin Institute of Technology | Xiong G.,Harbin Institute of Technology
Applied Catalysis B: Environmental | Year: 2013

Hollow sphere monoclinic scheelite BiVO4 (m-BiVO4) is simply synthesized via a simple hydrothermal method by using urea as guiding surfactant. The forming process is investigated to be the incorporation of bubble guiding, oriented attachment and Ostwald ripening. The heterostructured hollow spheres are built up of truncated octahedrons which are also found to be feasible based on theoretical calculation. The preferred truncated octahedron consists of {040}, {011}, and {110} crystal planes with multiplicities of 2, 2, and 4, respectively. Besides urea, different kinds of organic additives (citric acid, Vitamin C and oleic acid) are also chosen for the synthesis of m-BiVO4 to clarify the role of urea. The photocatalytic activities with different morphologies are evaluated on the degradation of Rhodamine B. It is found out that the m-BiVO4 with hollow structure shows the optimalizing activity and the reaction rate constant reaches up to 0.035min-1 without adding H2O2 as hydroxyl radicals provider. Except for activity, the as-prepared samples have high stability and durability, after four cycling runs of photodegradation of RhB, the photocatalytic ability of as-synthesized m-BiVO4 did not show any loss. The degradation of RhB is attributed to intrinsically strong photo-oxidation ability rather than photosensitization and the synthesized samples also shows efficient photocatalytic activity for the degradation of 2-propanol. Meanwhile, the reasons for the superior activity are also carefully investigated. © 2012 Elsevier B.V.


Yan J.,Harbin Institute of Technology | Feng C.,Harbin Institute of Technology
Clean Technologies and Environmental Policy | Year: 2014

Modular design is considered as one of the crucial techniques for product design process on account of enabling product to meet consumers' needs quickly, currently which focuses on enhancing 3R abilities (reuse, recycle, and reduce) promoted through green manufacturing. However, with the rising consciousness of sustainable development, a much broader focus of product modularity is needed for practical sustainable design and manufacturing, which are presented by 6R concept increasing recover, redesign, and remanufacture to the conventional 3R. This paper proposes an effective methodology of sustainable design oriented product modularity to integrate sustainable factors such as environment, economy, and society into product design process through the product representation with respect to module clustering criteria. Especially, the 6R concept is regarded as the basic principle of sustainable design and manufacturing, and hence, this article integrates 6R concept into module clustering criteria such as function, manufacturability, and end-of-life options to achieve objective of sustainable design. In addition, the relationship matrix between components is established utilizing design structure matrix which has great advantages on representing similarity and dependency relationship of component-to-component to determine module structure. Finally a rotor laboratory bench is utilized as a case study to illustrate the effectiveness of the proposed methodology. © 2013 Springer-Verlag Berlin Heidelberg.


Han X.,Harbin Institute of Technology | Wang L.,Harbin Institute of Technology | Wang X.,Harbin Institute of Technology
Advanced Functional Materials | Year: 2012

A novel, simple, versatile, rapid, and inexpensive method, "space limited oxygen plasma oxidation" is developed to fabricate chemical gradient on both alkylsilane and alkanethiol self-assembled monolayers (SAMs) surface. XPS data confirm that the methyl groups of alkane SAMs are converted into oxidized carbon functional groups. The influences of RF power, O 2 flow rate, and the "wedge" shape on gradient formation are investigated in details. Gradient surfaces with various scales and depths are formed by simply changing the 'wedge' shape or plasma generation parameters. The application of formed chemical gradient on droplet motion has been demonstrated as well. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Li L.,Harbin Institute of Technology | Liu D.-J.,Harbin Institute of Technology
International journal of environmental research and public health | Year: 2014

Since 2012, China has been facing haze-fog weather conditions, and haze-fog pollution and PM2.5 have become hot topics. It is very necessary to evaluate and analyze the ecological status of the air environment of China, which is of great significance for environmental protection measures. In this study the current situation of haze-fog pollution in China was analyzed first, and the new Ambient Air Quality Standards were introduced. For the issue of air quality evaluation, a comprehensive evaluation model based on an entropy weighting method and nearest neighbor method was developed. The entropy weighting method was used to determine the weights of indicators, and the nearest neighbor method was utilized to evaluate the air quality levels. Then the comprehensive evaluation model was applied into the practical evaluation problems of air quality in Beijing to analyze the haze-fog pollution. Two simulation experiments were implemented in this study. One experiment included the indicator of PM2.5 and was carried out based on the new Ambient Air Quality Standards (GB 3095-2012); the other experiment excluded PM2.5 and was carried out based on the old Ambient Air Quality Standards (GB 3095-1996). Their results were compared, and the simulation results showed that PM2.5 was an important indicator for air quality and the evaluation results of the new Air Quality Standards were more scientific than the old ones. The haze-fog pollution situation in Beijing City was also analyzed based on these results, and the corresponding management measures were suggested.


Deng L.,Nanjing University | Du Y.,Harbin Institute of Technology | Xu J.-J.,Nanjing University | Chen H.-Y.,Nanjing University
Biosensors and Bioelectronics | Year: 2014

This work demonstrates an aptasensor for ultrasensitive electrochemiluminescence (ECL) detection of thrombin based on an "off-on-off" approach. The system is composed of an Eu3+-doped CdS nanocrystals (CdS:Eu NCs) film on glassy carbon electrode (GCE) as ECL emitter. Then gold nanoparticles (AuNPs) labeled hairpin-DNA probe (ssDNA1) containing thrombin-binding aptamer (TBA) sequence was linked on the NCs film, which led to ECL quenching (off) as a result of Förster-resonance energy transfer (FRET) between the CdS:Eu NC film and the proximal AuNPs. Upon the occurrence of hybridization with its complementary DNA (ssDNA2), an ECL enhancement (on) occurred owing to the interactions of the excited CdS:Eu NCs with ECL-induced surface plasmon resonance (SPR) in AuNPs at large separation. Thrombin could induce ssDNA1 forming a G-quadruplex and cause the AuNPs to be close to CdS:Eu NCs film again, which resulted in an enhanced ECL quenching (off). This "off-on-off" system showed a maximum 7.4-fold change of ECL intensity due to the configuration transformation of ssDNA1 and provides great sensitivity for detection of thrombin in a wide detection range from 50aM to 1pM. © 2014 Elsevier B.V.


Qu Z.,Harbin Institute of Technology | Yu J.,Harbin Institute of Technology
Dianwang Jishu/Power System Technology | Year: 2013

Compared with traditional energy sources, wind power generation possesses advantages in energy saving and emission reduction, however, insufficient understanding of mutual variation properties of wind power limits the development and application of wind power to certain extent. According to the variation properties of wind power itself, the stationarity index is defined to evaluate the fluctuation extent of wind power or that of load power; for mutual variation properties; the consistency index is defined to evaluate the consistency of variation between power sources and the consistency of variation between energy source and load; the complementarity index is defined to evaluate the complimentary ability between power sources and the complimentary ability between power source and load, and to describe mutual variation properties common with consistency index, in addition sub-indices considering the variation direction are defined. The defined indices are compared with correlation coefficient and simultaneity index. Using the proposed indices, the stationarity, consistency and complementarity of the variability of load power and wind power among three wind farms located in the same region are calculated, thus the quantitative evaluation on variation characteristics of wind power under different conditions is implemented. The evaluation results based on the proposed indices are available for reference to the comparison among various kinds of power source characteristics and can offer information to guide the operation of wind farms.


Du C.,Harbin Institute of Technology | Chen M.,Harbin Engineering University | Wang W.,Harbin Engineering University | Yin G.,Harbin Institute of Technology
ACS Applied Materials and Interfaces | Year: 2011

Highly active and durable catalysts for formic acid oxidation are crucial to the development of direct formic acid fuel cell. In this letter, we report the synthesis, characterization, and electrochemical testing of nanoporous Pd57Ni43 alloy nanowires for use as the electrocatalyst towards formic acid oxidation (FAO). These nanowires are prepared by chemically dealloying of Ni from Ni-rich PdNi alloy nanowires, and have high surface area. X-ray diffraction data show that the Pd57Ni43 nanowires have the face-centered cubic crystalline structure of pure Pd, whereas X-ray photoelectron spectroscopy confirm the modification of electronic structure of Pd by electron transfer from Ni to Pd. Electrocatalytic activity of the nanowires towards FAO exceeds that of the state-of-the-art Pd/C. More importantly, the nanowires are highly resistant to deactivation. It is proposed that the high active surface area and modulated surface properties by Ni are responsible for the improvement of activity and durability. Dealloyed nanoporous Pd57Ni43 alloy nanowires are thus proposed as a promising catalyst towards FAO. © 2010 American Chemical Society.


Zheng S.,Harbin Institute of Technology
Structural Health Monitoring | Year: 2015

In this article, we inscribe long-period gratings on an SMF-28 optical fiber by a focused CO2 laser beam to develop a humidity sensor with high sensitivity and selectivity for moisture detection for civil infrastructures health monitoring. We propose two types of nano-structured film to deposit on surface of the grating region by electrostatic self-assembly deposition process. The primary nanofilm coating (PAH+/PAA−) does not affect long-period grating properties such as resonance wavelength and transmission intensity; however, it increases the sensitivity by changing the refractive index of the surrounding analytes. The secondary nanofilm coating (Al2O3+/PSS−), due to its molecule structure compatibility, can selectively adsorb analyte molecules of interest (in this case H2O only). The experimental results reveal that the nanofilm-coated long-period gratings are more sensitive to moisture in terms of both wavelength shift and resonance intensity change as of 0.019%/pm and 0.01%/10−3 dBm, respectively, while the bare LPG coefficients are 0.021%/pm and 0.0603%/10−3 dBm. The proposed sensor shows excellent thermal stability as well. © The Author(s) 2014


Han Y.,Harbin Institute of Technology | Qu S.,Harbin Institute of Technology
Chemical Physics Letters | Year: 2010

The surface configuration evolvement of silicon with the increasing pulse number irradiated by femtosecond laser has been studied. The ripples and nanoparticles are formed in the irradiated region. The period of the ripples decreases with the increasing pulse number, while the diameter of the visible structured region increases with the increasing pulse number. The interference of laser with surface plasmons is proposed to explain the formation of the ripple. The decreasing of the spatial period for surface ripples is due to the decrease of the surface plasmon wavelength with the decreasing electron number density in the plasma. © 2010 Elsevier B.V.


Liu M.,Harbin Institute of Technology | You J.,Harbin Institute of Technology
International Journal of Systems Science | Year: 2012

This article addresses the study of observer-based controller design for network-based control systems in the presence of output quantisation and random communication delay simultaneously. In the communication channel, the output measurement are quantised before transmission, and two kinds of network-induced delays are taken into account simultaneously: (i) random delay from sensor to controller and (ii) random delay from controller to actuator. These two types of random delays are modelled as two independent Bernoulli distributed white sequences. The observer-based controller is synthesised to stabilise the networked closed-loop system in the sense of stochastic stability. Sufficient conditions for the existence of the controller are provided by stochastic Lyapunov method. An illustrative numerical example is employed to demonstrate the applicability and flexibility of the proposed design strategy. © 2012 Copyright Taylor and Francis Group, LLC.


Yin J.Y.,Harbin Institute of Technology | Liu L.H.,Harbin Institute of Technology
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2010

The effects of morphological structure, water coating, dust mixing and primary particle size distribution on the radiative properties of soot fractal aggregates in atmosphere are investigated using T-matrix method. These fractal aggregates are numerically generated using a combination of the particle-cluster and cluster-cluster aggregation algorithms with fractal parameters representing soot aggregate in atmosphere. The radiative properties of compact aggregate notably deviate from that of the branched one, and the effect of morphology changes on the radiative properties in wet air cannot be neglected. However it is reasonable to use realization-averaged radiative properties to represent that of the aggregates with certain morphology. In wet air, the scattering, absorption and extinction cross-section and symmetry parameter of soot aggregates coated with water notably increase with water shell thickness. The mixing structures of dust have little effect on radiative properties of aggregates, but the volume fraction of dust has an obvious effect on extinction, scattering and absorption cross-section of aggregates when the size parameters are above the Rayleigh limit. Although the primary particle size distribution of soot aggregate has mild effect on the scattering albedo and asymmetry parameter, the deviations of the extinction, scattering, absorption cross-section among the three size distributions are significant in this study. The size distribution has a significant effect on forward scattering of phase function, while the effect can be neglected as the size parameter approaches to the Rayleigh limit. © 2010 Elsevier Ltd.


Niu B.,Harbin University of Science and Technology | Guo Y.,Harbin Institute of Technology
Physica D: Nonlinear Phenomena | Year: 2014

Distributed delay interactions among a group of Kuramoto phase oscillators are studied from the viewpoint of bifurcation analysis. After restricting the system on the Ott-Antonsen manifold, a simplified model consisting of delay differential equations is obtained. Hopf bifurcation diagrams are drawn on some two-parameter planes around the incoherent state when delay follows Dirac, uniform, Gamma and normal distributions, respectively, and it is illustrated that stronger coupling is needed to achieve synchrony when increasing the variance of either natural frequency or time delay. With the aid of center manifold reduction and the normal form method, the direction of Hopf bifurcation and stability of bifurcating periodic solutions are investigated, and the existence of the hysteresis loop is explained theoretically. © 2013 Elsevier B.V. All rights reserved.


Gao L.,Harbin Institute of Technology | Sun Y.G.,Harbin Institute of Technology
Journal of Thermophysics and Heat Transfer | Year: 2014

The fluid flow and heat transfer performance of composite lattice truss core sandwich structures with a constant localized internal heat source are numerically investigated under conditions of forced water convection for a wide range of Reynolds numbers. Three kinds of heat transfer methods are adopted: normal convective heat transfer, incident flow enhancement, and column support enhancement. The local thermal and fluid flow characteristics for this structure are analyzed to reveal the heat transfer mechanism, verifying that the multiform local vortical structures greatly contribute to the improvement in heat transfer efficiency. The heat transfer performance is characterized and assessed in terms of the thermal field distribution and the nondimensional heat transfer parameters of structure. In comparison with other heat dissipation media, a significant advantage is displayed for the comprehensive heat transfer performance of the structures. Much improvement and development space remain for the structural heat transfer performance, even for the achievement of multifunctional integration. © 2013 by the American Institute of Aeronautics and Astronautics, Inc.


Sun Y.,Harbin Institute of Technology | Gao L.,Harbin Institute of Technology
Materials and Design | Year: 2013

An improved-pyramidal truss core fabricated with a hot-press molding method is presented to manufacture carbon fiber-reinforced lattice truss sandwich structures in two steps. A series of analytical and experimental studies on structural responses and failure behaviors are carried out under the out-of-plane compressive and shear loading for all-composite improved-pyramidal truss sandwich panels with two relative densities. The size effect based on unit cell scale is explored under compression due to the contribution of the introduced cross-bars. Good agreement between the predictions and measurements based on Euler buckling and fracture failure of the struts is observed in uniaxial compressive tests, while greater deviation exists in shear tests due to the occurrence of dominated node rupture. The node failure is still a key issue for the improvement of structural mechanical performances. Taking this point into consideration, an expected interlacing layer form of pyramidal truss core is proposed to achieve further improvement. Comparisons suggest that the improved structure has relative excellent comprehensive properties. All these results also indicate that much space and opportunities still remain for the improvement and development of mechanical performances, even the achievement of structural multifunctional integration. © 2012 Elsevier Ltd.


Dai F.,Harbin Institute of Technology | Li H.,Harbin Institute of Technology | Du S.,Harbin Institute of Technology
Composite Structures | Year: 2013

This paper develops a multi-stable lattice structure consisting of tri-stable lattice cell which is made by bistable laminates. The multi-stable lattice structure with N tri-stable lattice cells, which can exhibit 2. N stable states, is successfully designed and fabricated. The critical loads snapping lattice structure are investigated by the experimental and finite element techniques. The method to simulate the behaviors of contact and constraint between the neighboring bistable laminates are presented. The snap through process of multi-stable lattice structures among multiple states are numerically simulated and experimentally validated. The multiple stabilities highlight the potential to achieve a smooth shape variation in the large area multi-stable structures. © 2012.


Bai Z.F.,Harbin Institute of Technology | Zhao Y.,Harbin Institute of Technology | Chen J.,Harbin Institute of Technology
Tribology International | Year: 2013

In this work, the dynamics and wear phenomenon of clearance joint in planar mechanical system is presented using a computational methodology. The contact model in clearance joint is established using a hybrid nonlinear contact force model and the friction effect is considered by using a modified Coulomb friction model. The wear prediction of revolute clearance joint in mechanical systems is presented based on the Archard wear model. Finally, the integration of dynamics analysis and wear analysis is presented. An academic four-bar multibody mechanical system with revolute clearance joint is used as numerical example application to perform the investigation. © 2013 Elsevier Ltd.


Li Y.,Harbin Institute of Technology | Qu S.,Harbin Institute of Technology
Current Applied Physics | Year: 2013

When the femtosecond laser focused in the water, the breakdown will be induced. The generated highspeed jet and shock wave can be used to etch silica glass for fabricating three-dimensional (3D) microfluidic chips. We present a simple and practical method to produce 3D multilayer microfluidic chips in silica glass. This method offers high design flexibility and fabricating feasibility. We also introduce a convenient cleaning method for diluting and ejecting the ablated debris from microchannel. Therefore, the femtosecond laser induced high-speed jet and shock wave can be used to fabricate complex microfluidic chips in silica glass. Experimental results show that the diameter of microchannel is uniform and the complexity of the microfluidic chip is under control. As a proof of principle, we demonstrate the feasibility of the fabricating process by using the water-assisted femtosecond laser ablation. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.


Zhang A.B.,Harbin Institute of Technology | Wang B.L.,Harbin Institute of Technology
International Journal of Solids and Structures | Year: 2013

It is well known that there is oscillation singularity near the interface crack tip, which is physically unreasonable. A modified interface dislocation model is developed to remove such oscillation singularity for interface fracture. The Dirac delta function in the fundamental solution of interface dislocation is explained by locally-distributed continuous function. The problem is reduced to the solution of a system of singular integral equations. The critical interfacial fracture mechanics parameters, such as the stress intensity factor, the mode mixity and the energy release rates for particular materials group are obtained. © 2012 Elsevier Ltd. All rights reserved.


Deng Y.,Harbin Institute of Technology | Zhang W.,Harbin Institute of Technology | Cao Z.,Harbin Institute of Technology
Materials and Design | Year: 2013

In this paper, the ballistic performance of single, two-, three- and four-layered steel plates impacted by ogival-nosed projectiles were experimentally investigated. Thin multi-layered plates arranged in various combinations of the same total thicknesses were normally impacted with the help of a gas gun. Ballistic limit velocity for each configuration target was obtained and compared based on the investigation of the effect of the air gap between layers, the number, order and thickness of layers on the ballistic resistance of targets. The results show that the thin monolithic targets have greater ballistic limit velocities than multi-layered targets if the total thickness less than a special value, and also the ballistic limit velocities of multi-layered targets decrease with the increase of the number of layers. Otherwise, the moderate thickness monolithic targets give lower ballistic limit velocities than multi-layered targets. Furthermore, the ballistic limit velocities of in-contact multi-layered targets are greater than those of spaced multi-layered targets. The order of layers affects the ballistic limit velocities of multi-layered targets, the ballistic resistance of the multi-layered targets is better when the first layer is thinner than the second layer. © 2012 Published by Elsevier Ltd.


Sun X.,Harbin Institute of Technology | Sun X.,Lawrence Berkeley National Laboratory
Nuclear Physics A | Year: 2014

We present triangular flow (v3) measured by STAR for identified particles (π±, K±, p, p- and ϕ) relative to the third-harmonic event plane as a function of pT for minimum bias (0%-80%) Au+Au collisions at √sNN=39GeV and 200 GeV. We discuss the hydrodynamic description of the mass ordering at low pT (pT<1.5GeV/c), number-of-constituent-quark (NCQ) scaling at intermediate pT (0.5GeV/c


Feng J.,Harbin Institute of Technology | Zeng M.,Harbin Institute of Technology
International Journal of Systems Science | Year: 2012

In this article, we study the distributed Kalman filtering fusion problem for a linear dynamic system with multiple sensors and cross-correlated noises. For the assumed linear dynamic system, based on the newly constructed measurements whose measurement noises are uncorrelated, we derive a distributed Kalman filtering fusion algorithm without feedback, and prove that it is an optimal distributed Kalman filtering fusion algorithm. Then, for the same linear dynamic system, also based on the newly constructed measurements, a distributed Kalman filtering fusion algorithm with feedback is proposed. A rigorous performance analysis is dedicated to the distributed fusion algorithm with feedback, which shows that the distributed fusion algorithm with feedback is also an optimal distributed Kalman filtering fusion algorithm; the P matrices are still the estimate error covariance matrices for local filters; the feedback does reduce the estimate error covariance of each local filter. Simulation results are provided to demonstrate the validity of the newly proposed fusion algorithms and the performance analysis. © 2011 Copyright Taylor and Francis Group, LLC.


Zhou B.,Harbin Institute of Technology | Duan G.-R.,Harbin Institute of Technology
IEEE Transactions on Automatic Control | Year: 2012

This note is concerned with stabilization of continuous-time periodic linear (CPL) systems with state feedback. The design is based on solutions to a class of parametric periodic Lyapunov differential equations (PLDEs) resulting from the problem of minimal energy control with guaranteed convergence rate. By carefully studying the properties of the PLDEs and their solutions, a continuous periodic state feedback is designed. The PLDE based approach is effective in designing stabilizing controller for CPL systems as the designers need only to solve a linear differential equation whose solution can be obtained analytically if the system is relative simple and can be computed numerically by integration in general cases. Necessary and sufficient conditions on the free parameter in the PLDE are proposed to guarantee the stability of the closed-loop system whose characteristic multiplier set can even be exactly computed accordingly. A numerical example is worked out to show the effectiveness of the proposed approach. © 2012 IEEE.


Li W.,Beijing Jiaotong University | Zhang X.,Harbin Institute of Technology | Cheng S.,Harbin Institute of Technology | Cao J.,Beijing Jiaotong University
IEEE Transactions on Industrial Electronics | Year: 2013

High-speed permanent-magnet generators (HSPMGs) are common and important power generation equipment used in distributed generation systems. A 100-kW-level HSPMG is investigated in this paper, and its cooling system is optimized through electromagnetic-fluid-thermal analysis. First, the 2-D electromagnetic field of the machine is calculated by using the time-stepping finite element method, and the electromagnetic performance and loss distributions (heat sources) are determined, particularly the eddy loss of the rotor sleeve. Then, a thermal analysis model of the fluid for the HSPMG is established. Through numerical calculating, the whole region 3-D temperature distribution in the HSPMG is obtained, in which the influence of temperature on material properties is considered. Considering the variations of heat transfer abilities of the cooling medium, the temperatures in machines with different cooling structures are comparatively analyzed, and new cooling grooves with variable cross sections are proposed, which make the temperatures in the machine lower and more evenly distributed. The obtained conclusions may provide useful reference for the optimal design and research of HSPMGs. © 2012 IEEE.


Zhao J.,Harbin Institute of Technology
Computers in Human Behavior | Year: 2010

During the epoch of knowledge-based economy and knowledge management, teachers must learn in order to improve professional development. The paper discusses on the problems of teacher professional development in China, and analyze on the relationship among teacher learning, teacher professional development and school knowledge management. From the perspective of schools, this study develops school knowledge management framework to facilitate teacher learning and improve teacher professional development, in the basis of this framework, schools' knowledge management strategies are presented, and provide references for administrators of schools. The result reveals the knowledge management strategies to improve teacher professional development, including school organizational reforger and knowledge leaders, constructing learning school and organization learning culture, establishing teacher knowledge management system of teacher professional development, encouraging team learning, teaching cooperation and knowledge sharing, establishing performance assessment mechanism of knowledge applications and development. © 2009 Elsevier Ltd. All rights reserved.


Jiang W.,Harbin Institute of Technology | Lin Y.,Harbin Institute of Technology
Computer Physics Communications | Year: 2010

In this paper, we consider practical numerical method to solve a space-time fractional advection-dispersion equation with variable coefficients on a finite domain. The equation is obtained from the standard advection-dispersion equation by replacing the first-order time derivative by the Caputo fractional derivative, and the first-order and second-order space derivatives by the Riemann-Liouville fractional derivative, respectively. Here, a new method for solving this equation is proposed in the reproducing kernel space. The representation of solution is given by the form of series and the n-term approximation solution is obtained by truncating the series. The method is easy to implement and the numerical results show the accuracy of the method. © 2009 Elsevier B.V. All rights reserved.


Wang B.L.,Harbin Institute of Technology | Wang K.F.,Harbin Institute of Technology
Composites Part B: Engineering | Year: 2013

Vibration of nanotubes embedded in an elastic matrix is investigated by using the nonlocal Timoshenko beam model. Both a stress gradient and a strain gradient approach are considered. The Hamilton's principle is adopted to obtain the frequencies of the nanotubes. The dependencies of frequency on the stiffness and mass density of the surrounding elastic matrix, the nonlocal parameter, the transverse shear stiffness and the rotary inertia of the nanotubes are obtained. The results show a significant dependence of frequencies on the surrounding medium and the nonlocal parameter. The frequencies are over-predicted by using the Euler beam model that neglects the shear stiffness and rotary inertia of the nanotubes. It is also found that the lower bound and the upper bound for the frequencies of nanotubes are, respectively, provided by the strain gradient model provides and the stress gradient theory. Explicit formulas for the frequency are obtained and therefore are easy to use by material scientists and engineers for the design of nanotubes and nanotubes based composites. © 2012 Elsevier Ltd. All rights reserved.


Qiu J.,Harbin Institute of Technology | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | Gao H.,Harbin Institute of Technology
IEEE Transactions on Fuzzy Systems | Year: 2012

This paper is concerned with the problem of robust ${\mathscr H}infty output feedback control for a class of continuous-time Takagi-Sugeno (T-S) fuzzy affine dynamic systems using quantized measurements. The objective is to design a suitable observer-based dynamic output feedback controller that guarantees the global stability of the resulting closed-loop fuzzy system with a prescribed ${\mathscr H}\infty disturbance attenuation level. Based on common/piecewise quadratic Lyapunov functions combined with S-procedure and some matrix inequality convexification techniques, some new results are developed to the controller synthesis for the underlying continuous-time T-S fuzzy affine systems with unmeasurable premise variables. All the solutions to the problem are formulated in the form of linear matrix inequalities (LMIs). Finally, two simulation examples are provided to illustrate the advantages of the proposed approaches. © 1993-2012 IEEE.


Hu Q.,Tianjin University | Zhang L.,Hong Kong Polytechnic University | An S.,Northeastern University China | Zhang D.,Hong Kong Polytechnic University | Yu D.,Harbin Institute of Technology
IEEE Transactions on Fuzzy Systems | Year: 2012

Rough sets, especially fuzzy rough sets, are supposedly a powerful mathematical tool to deal with uncertainty in data analysis. This theory has been applied to feature selection, dimensionality reduction, and rule learning. However, it is pointed out that the classical model of fuzzy rough sets is sensitive to noisy information, which is considered as a main source of uncertainty in applications. This disadvantage limits the applicability of fuzzy rough sets. In this paper, we reveal why the classical fuzzy rough set model is sensitive to noise and how noisy samples impose influence on fuzzy rough computation. Based on this discussion, we study the properties of some current fuzzy rough models in dealing with noisy data and introduce several new robust models. The properties of the proposed models are also discussed. Finally, a robust classification algorithm is designed based on fuzzy lower approximations. Some numerical experiments are given to illustrate the effectiveness of the models. The classifiers that are developed with the proposed models achieve good generalization performance. © 1993-2012 IEEE.


Chen H.,Harbin Institute of Technology | Sun D.,City University of Hong Kong
IEEE Transactions on Robotics | Year: 2012

Significant demand for both accuracy and productivity in batch manipulation of microparticles highlights the need to develop an automatic arraying approach to placing groups of particles into a predefined array with right pairs. This paper presents our latest effort to achieve this objective using integrated robotics and holographic optical tweezers technologies, where holographic optical tweezers function as special robot end-effectors to manipulate the microparticles. Based on the physical dynamics of trapping, a potential-field-based controller is developed to drive every pair of particles to the assigned array, while preventing collisions between particles. The significance of the proposed controller lies in the capability of driving two groups of particles into a common array in right pair and controlling the interdistances between the particles in pairs. Experiments are performed to demonstrate the effectiveness of the proposed approach. © 2012 IEEE.


Gao Y.,Harbin Institute of Technology | Hu H.,Harbin Institute of Technology
Geophysical Journal International | Year: 2010

Studied in this paper are the properties of seismoelectromagnetic waves radiated by a double couple in a saturated porous medium arising from the electrokinetic effect. First, using the Pride's equations, we derive the Green's function of the magnetic field due to a single point force as a complement of previous authors' works, in which only the Green's functions of the solid displacement, the relative fluid-solid displacement and the electric field were expressed. Furthermore, we extend these Green's functions to cater for the moment tensor sources. Then we derive the Green's functions of the solid displacement, the electric and magnetic fields in the frequency-space domain excited by a double couple source, which is frequently used in earthquake seismology. To visualize these fields, the radiation patterns are calculated and displayed. The results illustrate that the radiation pattern of the electric far field for the longitudinal (or transverse) wave is the same in shape as that of the far field of the P (or S) wave in elastodynamics. For a transverse wave, the electric and magnetic far fields share the same radiation patterns in shape, while the electric and magnetic near fields do not. For each of the four body waves, the far, intermediate and near fields are compared at different receiver-to-source distances, respectively. The electromagnetic (EM) wave has a much longer near-field-dominating distance than the seismic waves. We calculate the waveforms in the time-space domain by numerically Fourier transforming the Green's functions into the time domain. In order to validate these Green's functions and the waveforms, we calculate the waveforms again by another method. The main idea of the method is regarding the source as a displacement-stress-EM discontinuity vector. The result shows that the waveforms from those two methods are in excellent agreement. In the waveforms, there are the electric fields accompanying both the P and S waves, as well as the magnetic field accompanying the S wave. We testify that the S wave generally has a weaker capacity than the P wave in inducing an electric field. In the waveforms, there is also an independently propagating EM wave, which has a much higher speed than the seismic waves, and reaches the observation point immediately after the source launched. By comparing the waveforms at different receiving locations, we find that waveforms differ at different observation orientations. © 2010 The Authors Journal compilation © 2010 RAS.


Group substations have dominated district heating (DH) systems in China so far. In order to explore the applicability of building substations to DH systems in China, the case study has been carried out in Ulanhot, by comprehensively comparing the energy consumptions and costs of group and building substation systems. Firstly, building simulation is used to help design the substations and DH networks, and analyze the operation considering variable flow and holiday control, which revealed the energy-saving advantages and flexibility of the building substation system. Secondly, the structure of the outdoor network in the building substation system is redesigned using the results of building simulation. Then, the total energy consumption of the group and building substation systems, including heating energy, pumping energy, and heat loss, is simulated and compared, considering the regulation of the water temperature. According to the operation data of the group substation system in the last two heating periods, the relative error of the simulated total energy was -6.8%. Finally, the annual cost method is employed for the economic analysis, which shows the superiority of the building substation system with annual cost reductions ranging between 5.7 and 5.9% for a lifetime range of 10-30 years. © 2015.


Qiao W.-Q.,Harbin Institute of Technology
Chemical Research in Chinese Universities | Year: 2012

A new series of near infrared(NIR) electrochromic anthraquinone imides containing a triphenylamine moiety as an electron donor was synthesized and their electrochemical and spectroelectrochemical behavior were investigated. The results show that the new anthraquinone imides are redox active which can be reduced electrochemically from the neutral state to the radical anion form that absorbs in a range of 700-1200 nm.


Chen X.,Harbin Institute of Technology | Zhang N.,Harbin Institute of Technology | Sun K.,Harbin Institute of Technology
Electrochemistry Communications | Year: 2012

Nanoporous NiO films directly grown on the foam Ni are fabricated via a facile ammonia-induced route. As anode materials for lithium-ion batteries, nanoporous NiO films exhibit an outstanding rate capacity of 280 mAh·g - 1 at 10 C rate and high reversible capacity of 543 mAh·g - 1 after 100 cycles at 0.2 C rate. The fabrication strategy offers a novel approach to fabricate other thin film materials. © 2012 Elsevier B.V. All rights reserved.


Chen N.,Harbin Institute of Technology | Pan Q.,Harbin Institute of Technology
ACS Nano | Year: 2013

Ultralow-density (<10 mg cm-3) materials have many important technological applications; however, most of them were fabricated using either expensive materials or complicated procedures. In this study, ultralight magnetic Fe2O3/C, Co/C, and Ni/C foams (with a density <5 mg cm-3) were fabricated on the centimeter scale by pyrolyzing commercial polyurethane sponge grafted with polyelectrolyte layers based on the corresponding metal acrylate at 400 C. The ultralight foams consisted of 3D interconnected hollow tubes that have a diameter of micrometer and nanoscale wall thickness, forming hierarchical structures from macroscopic to nanometer length scales. More interesting was that the wall thickness and morphology of the microtubes could be tuned by controlling the concentrations of acrylic acid and metallic cations. After modification with low-surface-energy polysiloxane, the ultralight foams showed superhydrophobicity and superoleophilicity, which quickly and selectively absorbed a variety of oils from a polluted water surface under magnetic field. The oil absorption capacity reached 100 times of the foams' own weight, exhibiting one of the highest values among existing absorptive counterparts. By controlling the composition and conformation of the grafted polyelectrolyte layers, the present approach is extendable to fabricate a variety of ultralow-density materials desirable for absorptive materials, electrode materials, catalyst supports, etc. © 2013 American Chemical Society.


Zhang A.B.,Harbin Institute of Technology | Wang B.L.,University of New South Wales
International Journal of Solids and Structures | Year: 2013

Solutions are presented for an electrically impermeable crack branching out of the crack plane in a thermopiezoelectric medium under thermo-electro- mechanical loads based on Stroh formalism. Explicit Green's functions for the interaction of a crack and a thermopiezoelectric dislocation (i.e.; a thermal dislocation, a mechanical dislocation and an electric dipole located at the same point) are developed. The problem then can be expressed in terms of coupled singular integral equations for the thermopiezoelectric dislocation density functions associated with a branched crack. Some essential fracture mechanics parameters, such as stress and electric displacement intensity factors, and energy release rate at the branched crack tip are obtained. Numerical results are presented for the effect of applied thermal flux loads and electric field on the crack propagation path. © 2013 Elsevier Ltd. All rights reserved.


Muguthu J.N.,Harbin Institute of Technology | Gao D.,Harbin Institute of Technology
Materials and Manufacturing Processes | Year: 2013

Aluminum metal matrix composites (MMCs) are extensively used in electronic, automobile, and aerospace industries, but the abrasive nature of their reinforcement inhibits their machining due to excessive tool wear and poor surface finish. This article presents turning of Al2124SiCp (45%wt) MMC using polycrystalline diamond (PCD) and cBN (cubic boron nitride) tools. Tool wear, wear mechanism, surface profile fractal dimension, and dimensional accuracy are investigated. Most research on surface profile is based on the roughness parameter Ra whose reliability largely depends on the instrument used and its resolution. This can be solved by characterization of rough surfaces using scale consistent parameter as profile fractal dimension. Results reveal that tool wear mechanisms observed were abrasion, adhesion, chipping, and fracture. On the type of wear, for PCD tool flank and crater wear were observed, while for cBN tools, only flank wear was observed. PCD tool produced the highest fractal dimension values followed by coated cBN, while uncoated cBN tool had the lowest values. On dimensional accuracy, it was observed that PCD has the lowest diameter error followed by coated cBN and finally uncoated cBN. It is concluded that in machining Al2124SiCp (45%wt) MMC, PCD tools are the best, followed by coated cBN, and finally uncoated cBN tools. © 2013 Copyright Taylor and Francis Group, LLC.


Li Y.,Harbin Institute of Technology | Xu C.-Y.,Harbin Institute of Technology | Hu P.,Harbin Institute of Technology | Zhen L.,Harbin Institute of Technology
ACS Nano | Year: 2013

Carrier doping of MoS2 nanoflakes was achieved by functional self-assembled monolayers (SAMs) with different dipole moments. The effect of SAMs on the charge transfer between the substrates and MoS2 nanoflakes was studied by Raman spectroscopy, field-effect transistor (FET) measurements, and Kelvin probe microscope (KFM). Raman data and FET results verified that fluoroalkyltrichlorosilane-SAM with a large positive dipole moment, acting as hole donors, significantly reduced the intrinsic n-doping characteristic of MoS2 nanoflakes, while 3-(trimethoxysilyl)-1- propanamine-SAMs, acting as electron donors, enhanced the n-doping characteristic. The additional built-in electric field at the interface between SiO2 substrates and MoS2 nanoflakes induced by SAMs with molecular dipole moments determined the charge transfer process. KFM results clearly demonstrated the charge transfer between MoS2 and SAMs and the obvious interlayer screening effect of the pristine and SAM-modified MoS2 nanoflakes. However, the KFM results were not fully consistent with the Raman and FET results since the externally absorbed water molecules were shown to partially shield the actual surface potential measurement. By eliminating the contribution of the water molecules, the Fermi level of monolayer MoS2 could be estimated to modulate in a range of more than 0.45-0.47 eV. This work manifests that the work function of MoS2 nanoflakes can be significantly tuned by SAMs by virtue of affecting the electrostatic potential between the substrates and MoS2 nanoflakes. © 2013 American Chemical Society.


Xu L.,Harbin Institute of Technology | Zhou X.,Harbin Institute of Technology | Yu Y.,Harbin Institute of Technology | Tian W.Q.,Harbin Institute of Technology | And 2 more authors.
ACS Nano | Year: 2013

We performed a co-condensation reaction between aromatic aldehyde and aromatic diamine monomers on a highly oriented pyrolytic graphite surface either at a solid/liquid interface at room temperature or in low vacuum with moderate heating. With this simple and moderate methodology, we have obtained surface-confined 2D covalent organic frameworks (COFs) with few defects and almost entire surface coverage. The single crystalline domain can extend to more than 1 μm2. By varying the backbone length of aromatic diamines the pore size of 2D surface COFs is tunable from ∼1.7 to 3.5 nm. In addition, the nature of the surface COF can be modified by introducing functional groups into the aromatic amine precursor, which has been demonstrated by introducing methyl groups to the backbone of the diamine. Formation of small portions of bilayers was observed by both scanning tunneling microscopy (STM) and AFM, which clearly reveals an eclipsed stacking manner. © 2013 American Chemical Society.


Wang Z.,Harbin Institute of Technology | Li G.,Harbin Institute of Technology
Construction and Building Materials | Year: 2013

This paper presents the experimental results and prediction model for autogenous shrinkage (AS) of high performance concrete (HPC) with various water to cementitious materials ratios (w/cm), the replacement ratio of fly ash (FA), air content (AC), and aggregate to cementitious materials paste ratios (ACMR). These results are based on an experimental method for AS in HPC with a mold of low-density flexible corrugated pipe (LDFCP), which can continuously and automatically test AS after adding water. The results demonstrate the simplicity and accuracy of this experimental method. HPC with FA exhibited smaller AS than ordinary concrete with no FA with the same w/cm and higher replacement ratios of FA resulted in less AS. For the same content of FA, larger values of w/cm yielded less AS. The effect of AC on AS was optimum content and the effect of ACMR was an inverse ratio. A proposed prediction model can be successfully used to estimate the effects of w/cm, FA, AC and ACMR on the development of AS in HPC. © 2013 Published by Elsevier Ltd. All rights reserved.


Tan Y.,Harbin Institute of Technology | Guo M.,Harbin Institute of Technology
Construction and Building Materials | Year: 2013

In order to improve the road performance of asphalt mixture, the cohesion and adhesion of asphalt mastic which is the most important component of asphalt mixture were studied. The surface free energy of asphalt was tested using sessile drop method, and the surface free energy of fillers was measured using column wicking method. The work of cohesion and adhesion between asphalt and fillers were calculated through using their surface free energy parameters. The results show that the neat asphalt has higher surface free energy than the modified asphalt. The van der Waals force of surface free energy plays a more important role. The polarity power of modified asphalt is higher than the neat asphalt. The Lewis acid-alkali forces of different fillers have a big difference, while the van der Waals forces are nearly the same. Limestone filler has the biggest surface free energy and the components, and granite filler has the smallest intermolecular forces, and andesite filler has the smallest Lewis acid-alkali force. The specific surface area is an important parameter effecting the interfacial interaction between asphalt and fillers. The work of adhesion at a constant volume ratio has a better regularity than at a constant specific surface area regardless of whether the condition is dry or damp, whether the asphalt is modified or not, and the order is granite filler > andesite filler > limestone filler. A good correlation exists between complex modulus G * and work of adhesion. © 2013 Elsevier Ltd. All rights reserved.


Tan Y.,Harbin Institute of Technology | Guo M.,Harbin Institute of Technology
Construction and Building Materials | Year: 2013

In order to improve the road performance of asphalt mixture, the phase behavior of asphalt mastic which is the most important component of asphalt mixture was studied. The glass transition temperature (Tg) and glass transition activation energy of asphalt mastic were obtained by the dynamic mechanics analysis (DMA) method, and the effect of fillers on the distribution of wax in asphalt was studied by the differential scanning calorimetry (DSC). The effect of fillers on temperature sensitivity of asphalt mastic was studied through Brookfield viscometer. The phase separation of asphalt mastic and the applicability of time temperature superposition principle (TTSP) on asphalt mastic were studied by van Gurp-Palmen (vGP) plot. The results show that the faster the load frequency is, the higher Tg is, and the addition of fillers can increase Tg and glass transition activation energy. The distribution of wax in asphalt is discrete, and fillers have little impact on it. The addition of fillers can improve the temperature sensitivity of asphalt mastic, and the effect order is as follows: granite > andesite > limestone. The TTSP is effective for virgin asphalt at any temperature because of its homogeneity, but it is not effective for modified asphalt when the temperature is higher than 45 C because of its phase separation, and the addition of fillers can promote phase separation occur in modified asphalt. © 2013 Elsevier Ltd. All rights reserved.


Rehman S.,King Fahd University of Petroleum and Minerals | Al-Hadhrami L.M.,King Fahd University of Petroleum and Minerals | Alam M.M.,Harbin Institute of Technology
Renewable and Sustainable Energy Reviews | Year: 2015

The pumped hydro energy storage (PHES) is a well-established and commercially-acceptable technology for utility-scale electricity storage and has been used since as early as the 1890s. Hydro power is not only a renewable and sustainable energy source, but its flexibility and storage capacity also make it possible to improve grid stability and to support the deployment of other intermittent renewable energy sources such as wind and solar. As a result, a renewed interest in PHES and a demand for the rehabilitation of old small hydro power plants are emerging globally. With regard to PHES, advances in turbine design are required to enhance plant performance and flexibility and new strategies for optimizing storage capacity and for maximizing plant profitability in the deregulated energy market. In the early 2000s, this technology has again emerged as an economically and technologically acceptable option for peak load shaving and wind and solar energy storage for power quality assurance. Furthermore, renewable energy sources due to their fluctuating nature cannot maintain or regulate continuous supply of power and hence require bulk electricity storage. The present study aims at reviewing the existing global PHES capacities, technological development, and hybrid systems (wind-hydro, solar pv-hydro, and wind-pv-hydro) and recommending the best possible options. The review explores that PHES is the most suitable technology for small autonomous island grids and massive energy storage, where the energy efficiency of PHES varies in practice between 70% and 80% with some claiming up to 87%. Around the world, PHES size mostly nestles in the range of 1000-1500 MW, being as large as 2000-3000 MW. On the other hand, photovoltaic based pumped storage systems have been used for very small scale (load of few houses) only. © 2015 Elsevier Ltd All rights reserved.


Li F.-M.,Harbin Institute of Technology | Yao G.,Harbin Institute of Technology
Composite Structures | Year: 2013

The 1/3 subharmonic resonance of a composite laminated circular cylindrical shell with clamped boundary conditions at both ends in subsonic air flow under radial harmonic excitation is investigated. The equation of motion of the composite cylindrical shell is derived from the Donnell's nonlinear shell theory and the Galerkin's method is adopted to transform the equation of motion of the shell into a nonlinear ordinary differential equation. The 1/3 subharmonic resonance of the shell is analyzed by using the method of multiple scales and the sufficient and necessary conditions for the stability of the steady-states of the 1/3 subharmonic resonance is obtained by solving the eigenvalue problem of the linearized equations. The influences of the subsonic air flow on the 1/3 subharmonic resonance of the shell are discussed for different modes and the effects of the ply angles are analyzed for the fundamental mode. The numerical results of the threshold curves and the amplitude-frequency relations of the 1/3 subharmonic resonance are illustrated. From the results it can be seen that the existence region for the 1/3 subharmonic resonance is reduced and the amplitude of the subharmonic resonance is dropped with the flow velocity increasing. The composite shell with 45° ply angle exhibits better dynamic characteristic than that with other ply angles. The interval of the frequency ratio for the instability of the steady-state of the subharmonic resonance is broader when the ply angle is chosen as 45° than that of other ply angles for given amplitude of the external excitation. © 2013 Elsevier Ltd.


Liu J.,Harbin Institute of Technology | Pan Q.,Harbin Institute of Technology
Electrochemical and Solid-State Letters | Year: 2010

MnO/C nanocomposites for high capacity lithium-ion batteries were prepared through a simple thermal decomposition of manganese benzoate precursor at 500°C under air atmosphere. The obtained nanocomposites exhibited a reversible capacity greater than 680 mAh g-1 at the 50th cycle as well as a rate capability of 196 mAh g-1 at a current density of 1600 mA g-1. It was revealed that carbon content plays an important role in the electrochemical performance of MnO/C composites, and a content of 10.2 wt % is desirable for high reversible capacity and high rate capability. Owing to their excellent electrochemical properties and easy fabrication, these MnO/C composites might be promising high capacity anode materials for lithium-ion batteries. © 2010 The Electrochemical Society.


Weili L.,Harbin University of Science and Technology | Chunwei G.,Harbin Institute of Technology | Ping Z.,Harbin Institute of Technology
IEEE Transactions on Energy Conversion | Year: 2011

A significant problem of turbogenerators on complex end structures is overheating of local parts caused by end losses and complex fluid flow in the end region. Therefore, it is important to investigate the 3-D flow and heat transfer process in the end. Using a 200-MW air-cooled turbogenerator as an example, the influences of end cores and the actual shapes and material of the end coils, press finger, press plate, and copper shield are considered for the end field calculation; then, the physical and mathematical models of the coil end with involute portions are created. The 3-D electromagnetic field was calculated and the losses of different parts in the end and its distribution were obtained. Based on this, the losses from magnetic field calculations will be applied to the end as heat sources in the temperature field. For symmetry of the ventilated structure, the fluid and thermal physical models of the generator within the half-axial section were determined. A set of equations of fluid flow and heat transfer were derived from the fluid-solid conjugated heat transfer and the fluid and temperature distributions were obtained after solving the equations. All of the aforementioned will provide a theoretical basis for the generator safe operation. © 2011 IEEE.


Liu Z.,Harbin Institute of Technology | Guo Q.,Harbin Institute of Technology | Xu L.,Harbin Institute of Technology | Ahmad M.A.,COMSATS Institute of Information Technology | Liu S.,Harbin Institute of Technology
Optics Express | Year: 2010

We propose a double image encryption by using random binary encoding and gyrator transform. Two secret images are first regarded as the real part and imaginary part of complex function. Chaotic map is used for obtaining random binary matrix. The real part and imaginary part of complex function are exchanged under the control of random binary data. An iterative structure composed of the random binary encoding method is designed and employed for enhancing the security of encryption algorithm. The parameters in chaotic map and gyrator transform serve as the keys of this encryption scheme. Some numerical simulations have been made, to demonstrate the performance this algorithm. ©2010 Optical Society of America.


Xu Y.,Harbin Institute of Technology | Zhang D.,Harbin Institute of Technology | Zhang D.,Hong Kong Polytechnic University | Yang J.-Y.,Nanjing University of Science and Technology
Pattern Recognition | Year: 2010

Bimodal biometrics has been found to outperform single biometrics and are usually implemented using the matching score level or decision level fusion, though this fusion will enable less information of bimodal biometric traits to be exploited for personal authentication than fusion at the feature level. This paper proposes matrix-based complex PCA (MCPCA), a feature level fusion method for bimodal biometrics that uses a complex matrix to denote two biometric traits from one subject. The method respectively takes the two images from two biometric traits of a subject as the real part and imaginary part of a complex matrix. MCPCA applies a novel and mathematically tractable algorithm for extracting features directly from complex matrices. We also show that MCPCA has a sound theoretical foundation and the previous matrix-based PCA technique, two-dimensional PCA (2DPCA), is only one special form of the proposed method. On the other hand, the features extracted by the developed method may have a large number of data items (each real number in the obtained features is called one data item). In order to obtain features with a small number of data items, we have devised a two-step feature extraction scheme. Our experiments show that the proposed two-step feature extraction scheme can achieve a higher classification accuracy than the 2DPCA and PCA techniques. © 2009 Elsevier Ltd. All rights reserved.


Vogel D.,Harbin Institute of Technology
Procedia Computer Science | Year: 2016

Healthcare as currently practiced and supported is increasingly unaffordable and incapable of dealing with emerging population dynamics in virtually every country in the world. Sustained behaviour change, within which ICT will likely play a prominent role, is required to meet the needs of the future. ICT has the ability enable new approaches and amplify efforts. Towards that end, educated adult children are in a unique position to influence their parents' use of ICT in healthcare given their inherent ICT familiarity, learned subject matter expertise and family trust. This study uses the Elaboration Likelihood Model (ELM) as a guide to gather and analyze qualitative data from PhD students associated with an ehealth research institute to explore the persuasive impact of educated young adult children on their parents' use of ICT in healthcare. Results are presented. Implications for theory and practice are addressed. © 2016 The Authors.


Huang Y.,Harbin Institute of Technology
Structural Health Monitoring 2011: Condition-Based Maintenance and Intelligent Structures - Proceedings of the 8th International Workshop on Structural Health Monitoring | Year: 2011

Signal compression is often important to reduce the cost of data transfer and storage for structural health monitoring (SHM) systems of civil structures. Compressive sensing is a novel data compressing method whereby one does not measure the entire signal directly but rather a set of related ("projected") measurements. The length of the required compressive-sensing measurements is typically much smaller than the original signal, therefore increasing the efficiency of data transfer and storage. Recently, a Bayesian formalism has also been employed for optimal compressive sensing, which adopts the ideas in the relevance vector machine (RVM) as a decompression tool. In this article, we study the robustness of the BCS method. We show that the usual RVM optimization algorithm lacks robustness when the number of measurements is a lot less than the length of the signals because it can produce sub-optimal signal representations; as a result, BCS is not robust when high compression efficiency is required. This induces a tradeoff between efficiently compressing data and accurately decompressing it. Based on a study of the robustness of the BCS method, diagnostic tools are proposed to investigate whether the compressed representation of the signal is optimal. The numerical results also are given to validate the proposed method.


Wu S.,Harbin Institute of Technology | Wu S.,McGill University | Rabbat M.G.,McGill University
IEEE Transactions on Signal Processing | Year: 2013

We study a general framework for broadcast gossip algorithms which use companion variables to solve the average consensus problem. Each node maintains an initial state and a companion variable. Iterative updates are performed asynchronously whereby one random node broadcasts its current state and companion variables and all other nodes receiving the broadcast update their state and companion variables. We provide conditions under which this scheme is guaranteed to converge to a consensus solution, where all nodes have the same limiting values, on any strongly connected directed graph. Under stronger conditions, which are reasonable when the underlying communication graph is undirected, we guarantee that the consensus value is equal to the average, both in expectation and in the mean-squared sense. Our analysis uses tools from non-negative matrix theory and perturbation theory. The perturbation results rely on a parameter being sufficiently small. We characterize the allowable upper bound as well as the optimal setting for the perturbation parameter as a function of the network topology, and this allows us to characterize the worst-case rate of convergence. Simulations illustrate that, in comparison to existing broadcast gossip algorithms, the approaches proposed in this paper have the advantage that they simultaneously can be guaranteed to converge to the average consensus and they converge in a small number of broadcasts. © 1991-2012 IEEE.


Chen Q.,Harbin Institute of Technology | Chen C.,Harbin Institute of Technology | Guo F.,Harbin Institute of Technology | Xia W.,Harbin Institute of Technology
Chemical Communications | Year: 2013

Chiral N-tert-butylsulfinyl vinyl aziridine ligands prepared from a readily available (R)-tert-butanesulfinamide have been applied in the rhodium-catalyzed asymmetric 1,4-addition of aryl boronic acids to cyclic enones, which gives high yields and excellent enantioselectivities. © 2013 The Royal Society of Chemistry.


Ma L.,Harbin Institute of Technology | Zhang Y.,Harbin Institute of Technology | Yuan P.,Harbin Institute of Technology
Optics Express | Year: 2010

We investigated nonlinear optical properties of Phenoxyphthalocyanine (Pc1) and Phenoxy-phthalocyanine-Zinc(II) (Pc2) at a wavelength of 800 nm with 100 fs pulses .The nonlinear absorption coefficient (α) and nonlinear refractive index (n2) are measured using standard Z-scan technique. Open aperture Z-scan indicates strong threephoton absorption in both phthalocyanines. With good solubility and excellent nonlinear optical coefficient,the samples are expected to be a potential candidate for optical applications. © 2010 Optical Society of America.