Shenyang, China

Northeastern University is a public university in the city of Shenyang, Liaoning Province, China. With an annual enrollment of over 20,000 students, it is one of China's high level universities designated for the state key construction of the 211 Project and 985 Project. Wikipedia.


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The present invention relates to controlled cooling in manufacture of steel plate, and in particular, to an on-line cooling system for controlled rolling with an inter-pass cooling process, which comprises a rolling mill and on-line cooling equipment. The cooling equipment is accessorily arranged on the exit of the rolling mill, so that the rolling mill and the cooling equipment are combined. One rolling mill and one set of on-line cooling equipment are considered a cooling group, and several such groups are connected in series, so the steel plate can be cooled in any rolling pass. In this invention, both the cooling system and the water supply system are arranged on the main frame, and the rolling process and the cooling process are synchronized by using inter-pass cooling. Consequently, satisfied rolling effect in the condition of a temperature gradient along the thickness direction, grain refinement at the surface and drastic strength improvement without sacrificing toughness are achieved. Besides, better quality of the plate center region is obtained, double bulging is avoided and the yield of steel plate is improved due to the higher deformation permeability.


A method for recovering alkali and aluminum during treatment of Bayer red mud using a calcification-carbonation method, including steps of mixing the Bayer red mud with calcium aluminate or with calcium aluminate and lime, performing calcification dealkalization conversion in a high-concentration alkaline liquor, and carbonizing the calcified residues produced during dealkalization to obtain carbonized residues; and then performing low-temperature aluminum dissolution, aluminum precipitation and the like to obtain calcium aluminate products, which is returned to the calcification dealkalization conversion of the red mud for recycling. Part of an alkali-containing and aluminum-containing liquid phase after calcification dealkalization conversion can be used as supplementary alkali in the Bayer production course for recycling. The method is energy-saving and environmentally-friendly, and allows recovering alkali and aluminum from the red mud and harmless treatment of the Bayer red mud.


Patent
Northeastern University China | Date: 2017-01-18

The present invention relates to a preparation method of high oriented silicon steel, and belongs to the technical field of metallurgy. The preparation method is performed according to the following steps of: (1) melting to obtain molten steel according to set components in percentage by weight: 0.001-0.003% of C, 5.0-6.6% of Si, 0.2-0.3% of Mn, 0.05-0.12% ofAl , 0.01-0.04% of V, 0.03-0.06% of Nb, 0.02-0.03% of S, 0.009-0.020% of N, O which is less than or equal to 0.0020%, and the balance being Fe and unavoidable impurities; (2) forming cast strips after a thin-strip casting course; (3) hot-rolling the cast strips under inert atmosphere conditions; (4) cooling the hot-rolled cast strips to 550-600 DEG C, coiling the cooled cast strips, and performing low-temperature hot rolling/warm rolling on the coiled cast strips under a nitrogen atmosphere condition; (5) removing oxidized scales though pickling, and then performing cold rolling for multiple times; (6) performing recrystallization annealing, coating with an MgO layer, and finally coiling; (7) performing purification annealing under hydrogen circulation conditions; and (8) removing oxidized scales, coating with an insulating layer, performing flat stretch annealing, and performing air-cooled coiling.


The present invention relates to the field of environmental protection, in particular to a method for recovering alkali and aluminum in the course of treatment of Bayer red mud by using a calcification-carbonation method. The method comprises the following steps of after mixing the Bayer red mud with calcium aluminate or with the calcium aluminate and lime, performing calcification dealkalization conversion in high-concentration alkaline liquor of which the caustic alkali concentration is 100-300g/L, enabling all of a silicon-containing phase in the red mud to be converted into hydrated garnet to enter calcified residues produced during dealkalization, and carbonizing the calcified residues so as to obtain carbonized residues; and then performing the working procedures including low-temperature aluminum dissolution, aluminum precipitation and the like so as to obtain calcium aluminate products, wherein the calcium aluminate is returned to the course of the calcification dealkalization conversion of the red mud for recycling. Part of an alkali-containing and aluminum-containing liquid phase after calcification dealkalization conversion can be used as supplementary alkali in a Bayer production course for recycling. According to the method disclosed by the present invention, recovering alkali and aluminum from the red mud and harmless treatment of the Bayer red mud can be realized, so that the method is an energy-saving environmentally-friendly utilization method of the red mud.


Liu J.-W.,Northeastern University China | Zhang Y.,Northeastern University China | Chen X.-W.,Northeastern University China | Wang J.-H.,Northeastern University China
ACS Applied Materials and Interfaces | Year: 2014

Graphene oxide-La(BTC)(H2O)6 (H3BTC=1,3,5- benzenetricarboxylic acid) metal organic framework composites (LaMOF-GO n, n = 1-6, corresponding to the percentage of GO at 1, 2, 3, 4, 5, and 10%) are prepared through a simple and large-scale method at room temperature. The obtained composites are characterized by ATR-FTIR spectra, SEM, XRD, TGA, and N2 adsorption-desorption isotherm. The presence of GO significantly changes the morphologies of the composites from spindly rectangular rods to irregular thick blocks and increases their surface area from 14.8 cm2 g-1 (LaMOFs) to 26.6 cm2 g -1 (LaMOF-GO3), whereas at the same time, the crystalline structure of La(BTC)(H2O)6 is maintained. As a novel solid-phase adsorbent the LaMOF-GO composite exhibits outstanding adsorption properties for proteins. The strong hydrophobic interaction, especially π-π interaction between protein and the composite, is the main driving force for protein adsorption. In particular, highly selective isolation of hemoglobin (Hb) is achieved by using LaMOF-GO3 composite as sorbent in 4 mM B-R buffer containing 0.05 mol L-1 NaCl at pH 8. The retained Hb could be effectively recovered with a 1 mM B-R buffer at pH 10, giving rise to a recovery of 63%. The practical applicability of the LaMOF-GO3 composite is demonstrated by the selective adsorption of Hb from human whole blood, and SDS-PAGE assays indicate that Hb could be selectively isolated with high purity from biological samples of complex matrixes. © 2014 American Chemical Society.


Lv R.-Q.,Northeastern University China | Zhao Y.,Northeastern University China | Wang D.,Northeastern University China | Wang Q.,Northeastern University China
IEEE Photonics Technology Letters | Year: 2014

Magnetic fluid is a new type of optical functional material, which has interesting optical characteristics under an external magnetic field. In this letter, the magneto-optical characteristic of the magnetic fluid was adopted to form a novel fiber-optic magnetic field sensor. The sensor probe was composed of an extrinsic fiber Fabry-Pérot interferometer and magnetic fluid. The refractive index of the magnetic fluid would be changed with the increase of magnetic field. Preliminary experiment was carried out to verify the feasibility of the sensor. The magnetic field measurement sensitivity was 0.0431 nm/Gs in the experiment. The measurement resolution was better than 0.5 Gs at the measurement range from 0 to 400 Gs. The sensor has the advantages of simple structure, compact size, and easy fabrication. © 2013 IEEE.


Niu N.,Mississippi State University | Xu L.D.,Northeastern University China | Xu L.D.,Shanghai JiaoTong University | Xu L.D.,Old Dominion University | Bi Z.,Indiana University - Purdue University Fort Wayne
IEEE Transactions on Industrial Informatics | Year: 2013

Numerous software architecture proposals are available to industrial information engineers in developing their enterprise information systems. While those proposals and corresponding methodologies are helpful to engineers in determining appropriate architecture, the systematic methods for the evaluation of software architecture are scarce. To select appropriate software architecture from various alternatives appropriately, a scenario-based method has been proposed to assess how software architecture affects the fulfillment of business requirements. The empirical evaluation on the selection of a supply chain software tool has shown that the developed method offers remarkable insights of software development and can be incorporated into the industrial informatics practice of an organization with a moderate cost. © 2013 IEEE.


Hu J.,Northeastern University China | Du L.-X.,Northeastern University China | Wang J.-J.,Northeastern University China | Sun Q.-Y.,WISDRI Engineering and Research Incorporation Ltd
Materials and Design | Year: 2014

For the purpose of developing Nb-V-Ti microalloyed, hot rolled, high strength automotive steel for usage in heavy-duty truck wheel-discs and wheel-rims, appropriate cooling processes were designed, and microstructures and comprehensive mechanical properties (tension, bending, hole-expansion, and Charpy impact) of the tested steels at two cooling schedules were studied. The results indicate that the steel consists of 90% 5. μm polygonal ferrite and 10% pearlite when subjected to a cooling rate of 13. °C/s and a coiling temperature of 650. °C. The yield strength, tensile strength, and hole-expansion ratio are 570. MPa, 615. MPa, and 95%, respectively, which meet the requirements of the wheel-disc application. The steel consists of 20% 3. μm polygonal ferrite and 80% bainite (granular bainite and a small amount of acicular ferrite) when subjected to a cooling rate of 30. °C/s and a coiling temperature of 430. °C. The yield strength, tensile strength, and hole-expansion ratio are 600. MPa, 655. MPa, and 66%, respectively, which meet the requirements of the wheel-rim application. Both the ferrite-pearlite steel and ferrite-bainite steel possess excellent bendability and Charpy impact property. The precipitation behavior and dislocation pattern are characterized and discussed. © 2013 Elsevier Ltd.


Sun Q.,Northeastern University China | Han R.,Northeastern University China | Zhang H.,Northeastern University China | Zhou J.,Northeastern University China | Guerrero J.M.,University of Aalborg
IEEE Transactions on Smart Grid | Year: 2015

With the bidirectional power flow provided by the Energy Internet, various methods are promoted to improve and increase the energy utilization between Energy Internet and main grid (MG). This paper proposes a novel distributed coordinated controller combined with a multiagent-based consensus algorithm, which is applied to distributed generators in the Energy Internet. Then, the decomposed tasks, models, and information flow of the proposed method are analyzed. The proposed coordinated controller installed between the Energy Internet and MG keeps voltage angles and amplitudes consensus, while providing accurate power-sharing and minimizing circulating currents. Finally, the Energy Internet can be integrated into the MG seamlessly if necessary. Hence, the Energy Internet can be operated as a spinning reserve system. Simulation results are provided to show the effectiveness of the proposed controller in an Energy Internet. © 2010-2012 IEEE.


Zhang J.-F.,Northeastern University China | Li Y.-H.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

Consistency tests for the general relativity (GR) can be performed by constraining the growth index γ using the measurements of redshift-space distortions (RSD) in conjunction with other observations. In previous studies, deviations from the GR expected value of γ. ≈. 0.55 at the 2-3. σ level were found. In this work, we reconsider the measurement of γ in a Universe with sterile neutrinos. We constrain the sterile neutrino cosmological model using the RSD measurements combined with the cosmic microwave background data (Planck temperature data plus WMAP 9-yr polarization data), the baryon acoustic oscillation data, the Hubble constant direct measurement, the Planck Sunyaev-Zeldovich cluster counts data, and the galaxy shear data. We obtain the constraint result of the growth index, γ=0.584-0.048+0.047, well consistent with the GR expected value (the consistency is at the 0.6. σ level). For the parameters of sterile neutrino, we obtain Neff=3.62-0.42+0.26 and mν,sterileeff=0.48-0.14+0.11 eV. We also consider the BICEP2 data and perform an analysis on the model with tensor modes. Similar fit results are obtained, showing that once light sterile neutrino is considered in the Universe, GR will become well consistent with the current observations. © 2014 The Authors.


Xu L.D.,Shanghai JiaoTong University | Xu L.D.,Old Dominion University | Wang C.,Northeastern University China | Bi Z.,Indiana University - Purdue University Fort Wayne | Yu J.,Northeastern University China
IEEE Transactions on Industrial Informatics | Year: 2012

To automate assembly planning for complex products such as aircraft components, an assembly planning and simulation system called AutoAssem has been developed. In this paper, its system architecture is presented; the main components and the key technologies in each component are discussed. The core functions of the system that have been focused include Digital Assembly Modeling, Assembly Sequence Planning (ASP), Path Planning, Visualization, and Simulation. In contrast to existing assembly planning systems, one of the novelties of the system is it allows the assembly plans be automatically generated from a CAD assembly model with minimal manual interventions. Within the system, new methodologies have been developed to: (i) create Assembly Relationship Matrices; (ii) plan assembly sequences; (iii) generate assembly paths; and (iv) visualize and simulate assembly plans. To illustrate the application of the system, the assembly of a worm gear reducer is used as an example throughout this paper for demonstration purpose. AutoAssem has been successfully applied to virtual assembly design for various complex products so far. © 2005-2012 IEEE.


Cai Z.H.,Northeastern University China | Ding H.,Northeastern University China | Misra R.D.K.,University of Louisiana at Lafayette | Kong H.,Northeastern University China
Scripta Materialia | Year: 2014

We describe here an intriguing and unique serrated flow behavior in a hot-rolled Fe-11Mn-4Al-0.2C transformation-induced plasticity (TRIP) steel, subjected to an optimized quenching and tempering (Q&T) treatment. The optimized Q&T treatment produced a ferrite-austenite microstructure that was characterized by serrated flow during tensile straining. The serrated behavior is attributed to a discontinuous TRIP effect involving stress relaxation and transfer during deformation with consequent enhancement in ductility. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Wu L.-X.,Beijing Normal University | Wu L.-X.,China University of Mining and Technology | Qin K.,China University of Mining and Technology | Liu S.-J.,Northeastern University China
Proceedings of the IEEE | Year: 2012

Although earthquakes are difficult to be predicted because of the complexity of the Earth system and the uncertainty of seismogenic processes, GEOSS provides multiple sources of observation data and brings a possibility to extract a thermal anomaly that would have a significant effect on earthquake prediction. Referring to the analysis on the lithosphere-coversphere-atmosphere (LCA) coupling due to stress enhancement in seismogenic zone, six thermal parameters, including surface latent heat flux (SLHF), thermal infrared radiation (TIR), outgoing longwave radiation (OLR), diurnal temperature range (DTR), atmospheric temperature, and skin temperature, are selected for GEOSS-based earthquake anomaly recognition (EAR). The inherent relations between the six thermal parameters are preliminarily introduced in consideration of possible LCA coupling. With overquantity, quasi-synchronism, and geo-consistency being defined as three rules for data mining, a deviation-time-space-thermal (DTS-T) EAR method as well as its procedures are developed in this paper. With 2008 M7.3 Yutian earthquake, China, 2008 M8.0 Wenchuan earthquake, China, and 2010 M7.1 Christchurch earthquake, New Zealand, being examples of tectonic earthquakes, the technical procedures of DTS-T method are demonstrated, which show that the obtained compositive thermal anomaly has a significant effect on earthquake prediction. © 2012 IEEE.


Zhao Y.,Northeastern University China | Deng Z.-Q.,Northeastern University China | Wang Q.,Northeastern University China
Sensors and Actuators, B: Chemical | Year: 2014

A novel chemical method based on silver mirror reaction is proposed to fabricate the optic fiber surface plasmon resonance sensing probe for liquid concentration measurement. Compared to traditional physical methods, this chemical method is more convenient, resources conservation and inexpensive. And it does not need any complicated equipment. A liquid concentration measurement system with end-reflection optic fiber SPR sensor was set up. Then the comparison experiment between darkroom environment and natural light environment was conducted. As a result, the effect from natural light was eliminated. Glycerol solutions with different volume concentrations (from 0% to 50%) were measured, and the shifts in resonance wavelength were obtained. The sensitivity of the sensor is found to range from 346.7 nm/% to 890.7 nm/%. © 2013 Elsevier B.V.


Cai Z.H.,Northeastern University China | Ding H.,Northeastern University China | Xue X.,Northeastern University China | Jiang J.,Northeastern University China | And 2 more authors.
Scripta Materialia | Year: 2013

In the context of obtaining high strength-high ductility combination in transformation-induced plasticity steels, we underscore the practical significance of controlling the stability of austenite during deformation such that strain hardening induced by martensite transformation occurs at a critical strain. An optimized intercritical hardening at 750 °C led to a ferrite-austenite microstructure that was characterized by ∼64% austenite and excellent combination of tensile strength of ∼1000 MPa and elongation of ∼65%, and a three-stage work hardening behavior.© 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Chai T.,Northeastern University China | Jin Y.,University of Surrey | Sendhoff B.,Honda Research Institute Europe
IEEE Computational Intelligence Magazine | Year: 2013

The papers in this special section focus on the challenges and future direction of evolutionary complex engineering. © 2005-2012 IEEE.


Qin H.-L.,Northeastern University China
Procedia Engineering | Year: 2011

According to the character of the high-rise buildings fire risk, this paper establishes the index system of fire risk on high-rise building, calculates the weight of every index by AHP, applies fuzzy pattern recognition model with the least summation of weighted generalized distance in fuzzy comprehensive assessment, sets up the fire risk assessment model of high-rise buildings based on the fuzzy pattern recognition and brings in fuzzy characteristic quantity of safety grade to deal with the assessment result of fire risk on high-rise building. At last, this method stated above is applied to some hotel in Xi'an which can provide available gist for performance-based fire protection design and safety management. © 2011 Published by Elsevier Ltd.


Xu J.,Northeastern University China | Zhang Z.,National University of Singapore | Tung A.K.H.,National University of Singapore | Yu G.,Northeastern University China
Proceedings of the VLDB Endowment | Year: 2010

Probabilistic data is coming as a new deluge along with the technical advances on geographical tracking, multimedia processing, sensor network and RFID. While similarity search is an important functionality supporting the manipulation of probabilistic data, it raises new challenges to traditional relational database. The problem stems from the limited effectiveness of the distance metric supported by the existing database system. On the other hand, some complicated distance operators have proven their values for better distinguishing ability in the probabilistic domain. In this paper, we discuss the similarity search problem with the Earth Mover's Distance, which is the most successful distance metric on probabilistic histograms and an expensive operator with cubic complexity. We present a new database approach to answer range queries and k-nearest neighbor queries on probabilistic data, on the basis of Earth Mover's Distance. Our solution utilizes the primal-dual theory in linear programming and deploys B + tree index structures for effective candidate pruning. Extensive experiments show that our proposal dramatically improves the scalability of probabilistic databases. © 2010 VLDB Endowment.


Chen S.,Northeastern University China | Hai X.,Northeastern University China | Chen X.-W.,Northeastern University China | Wang J.-H.,Northeastern University China
Analytical Chemistry | Year: 2014

We report a facile green approach for in situ growth of silver nanoparticles (AgNPs) on the surface of graphene quantum dots (GQDs). GQDs serve as both reducing agent and stabilizer, and no additional reducing agent and stabilizer is necessary. The GQDs/AgNPs hybrid exhibits a superior absorbance fading response toward the reduction of H2O2. A simple colorimetric procedure is thus proposed for ultrasensitive detection of H 2O2 without additional chromogenic agent. It provides a record detection limit of 33 nM for the detection of H2O2 by the AgNPs-based sensing system. This colorimetric sensing system is further extended to the detection of glucose in combination with the specific catalytic effect of glucose oxidase for the oxidation of glucose and formation of H 2O2, giving rise to a detection limit of 170 nM. The favorable performances of the GQDs/AgNPs hybrid are due to the peroxidase-like activity of GQDs. © 2014 American Chemical Society.


Liu Y.,Northeastern University China | Guo L.,Northeastern University China | Wei X.,University of California at Riverside
Journal of Lightwave Technology | Year: 2012

Survivability is one of the key issues in hybrid wireless-optical broadband access networks (WOBAN) since the single segment failure can cause huge data loss. The single segment failure refers to a scenario where all optical-network-units (ONUs) are disconnected with the optical line terminal (OLT). Previous schemes focus on protecting WOBAN against single segment failure by deploying backup fibers. However, previous schemes suffer from two key problems. First, they ignore optimizing the selection of backup ONUs, which determines the cost of recovering the traffic interrupted by the failure. Second, they underutilize the residual capacity of segments, thus requiring higher backup fibers cost. In this paper, we propose a new and efficient scheme, called Optimizing Backup ONUs selection and backup Fibers deployment (OBOF), to enhance the survivability of WOBAN against the single segment failure. Our OBOF is composed of two consecutive steps, backup ONUs selection and backup fibers deployment. In the first step, aiming to minimize the cost of recovering the traffic interrupted by the failure, the simulated annealing (SA) algorithm is customized to optimize the selection of backup ONUs. In the second step, most importantly, an enhanced greedy cost-efficiency (EGCE) algorithm is proposed to optimize the deployment of backup fibers. Our EGCE consists of a novel remote backup segment (RBS) method, which can efficiently utilize the residual capacity of the segments, and a Bound on Length of Backup-optical-path (BLB) method, which limits the increase in recovery time induced by RBS. Extensive experimental results demonstrate that our OBOF scheme outperforms the previous schemes significantly, especially in the scenario of higher traffic demand. © 2012 IEEE.


Zhang H.,Northeastern University China | Song R.,Northeastern University China | Wei Q.,CAS Institute of Automation | Zhang T.,Shenyang Institute of Engineering
IEEE Transactions on Neural Networks | Year: 2011

In this paper, a novel heuristic dynamic programming (HDP) iteration algorithm is proposed to solve the optimal tracking control problem for a class of nonlinear discrete-time systems with time delays. The novel algorithm contains state updating, control policy iteration, and performance index iteration. To get the optimal states, the states are also updated. Furthermore, the backward iteration is applied to state updating. Two neural networks are used to approximate the performance index function and compute the optimal control policy for facilitating the implementation of HDP iteration algorithm. At last, we present two examples to demonstrate the effectiveness of the proposed HDP iteration algorithm. © 2011 IEEE.


Wang J.,Macau University of Science and Technology | Wang C.-H.,National Chiao Tung University | Wang C.-H.,Northeastern University China | Chen C.L.P.,Macau University of Science and Technology
IEEE Transactions on Fuzzy Systems | Year: 2014

In this paper, a fuzzy neural network (FNN) is transformed into an equivalent three-layer fully connected neural inference system (F-CONFIS). This F-CONFIS is a new type of a neural network whose links are with dependent and repeated weights between the input layer and hidden layer. For these special dependent repeated links of the F-CONFIS, some special properties are revealed. A new learning algorithm with these special properties is proposed in this paper for the F-CONFIS. The F-CONFIS is therefore applied for finding the capacity of the FNN. The lower bound and upper bound of the capacity of the FNN can be found from a new theorem proposed in this paper. Several examples are illustrated with satisfactory simulation results for the capacity of the F-CONFIS (or the FNN). These include "within capacity training of the FNN," "over capacity training of the FNN, " "training by increasing the capacity of the FNN," and "impact of the capacity of the FNN in clustering Iris Data." It is noted that the finding of the capacity of the F-CONFIS, or FNN, has its emerging values in all engineering applications using fuzzy neural networks. This is to say that all engineering applications using FNN should not exceed the capacity of the FNN to avoid unexpected results. The clustering of Iris data using FNN illustrated in this paper is one of the most relevant engineering applications in this regards. © 2014 IEEE.


Gao S.Z.,Shenyang University of Chemical Technology | Wang J.S.,University Of Science And Technology Liaoning | Gao X.W.,Northeastern University China
Journal of Process Control | Year: 2013

Based on data driven modeling theory, PVC polymerization process modeling and intelligent optimization control algorithm is studied. Firstly, a multi-T-S fuzzy neural networks soft-sensing model combining the principal component analysis (PCA) and fuzzy c-means (FCM) clustering algorithm is proposed to predict the convention rate and velocity of Vinyle Chloride Monomer (VCM). The proposed hybrid learning algorithm utilizing the harmony search (HS) and least square method is used to adjust the model premise parameters and consequent parameters. Secondly, the generalized predictive control (GPC) algorithm of polymerizer temperature based on segmental affine is proposed. According to dynamic equation of polymerizer temperature deduced by heat balance mechanism, the segmental affine model is built by temperature and convention rate of the polymerizer. Then linear matrix inequality (LMI) method is used to design the controller. Finally, simulation results and industrial application show the validity and feasibility of the proposed control strategy. © 2013 Elsevier Ltd. All rights reserved.


Xie X.,Henan Polytechnic University | Ma H.,Northeastern University China | Zhao Y.,Shenyang Institute of Engineering | Ding D.-W.,University of Science and Technology Beijing | Wang Y.,Northeastern University China
IEEE Transactions on Fuzzy Systems | Year: 2013

This paper proposes relaxed stabilization conditions of discrete-time nonlinear systems in the Takagi-Sugeno (T-S) fuzzy form. By using the algebraic property of fuzzy membership functions, a novel nonparallel distributed compensation (non-PDC) control scheme is proposed based on a new class of fuzzy Lyapunov functions. Thus, relaxed stabilization conditions for the underlying closed-loop fuzzy system are developed by applying a new slack variable technique. In particular, some existing fuzzy Lyapunov functions and non-PDC control schemes are special cases of the new Lyapunov function and fuzzy control scheme, respectively. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed method. © 2012 IEEE.


Guo X.-G.,Tianjin University of Technology | Yang G.-H.,Northeastern University China | Che W.-W.,Shenyang University
Journal of the Franklin Institute | Year: 2013

This paper will focus on designing insensitive output feedback controllers for linear continuous-time systems with mixed-H∞ norm sensitivity minimization. In order to reduce the sensitivity of the designed controllers, a type of coefficient sensitivity function with respect to additive controller coefficient variations is defined. What's more, the H ∞ norms of the coefficient sensitivity functions are regarded as sensitivity indexes. Then, the considered problem in this paper is reduced to a multi-objective problem which is to be a non-convex optimization problem, where both the coefficient sensitivity constraint and the standard H ∞ norm constraint are considered simultaneously. To solve this non-convex problem, a two-step procedure is adopted to obtain the solutions through satisfying a set of linear matrix inequalities (LMIs). It is worth to mention here that the non-fragile control method is adopted to obtain an effective initial solution of the two-step procedure. Finally, a numerical example is also given to demonstrate the effectiveness of the proposed design procedure. © 2012 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.


Wang J.-W.,Dali University | Wang J.-W.,Northeastern University China | Zhang B.-Y.,Northeastern University China
Liquid Crystals | Year: 2013

A series of liquid crystalline polymers (LCPs) have been synthesised by two cholesteric monomers M1, M2 and a nematic monomer M3. The chemical structures and liquid crystalline properties of the monomers and polymers have been characterised by FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analyses, X-ray diffraction measurements and polarising optical microscopy. All LCPs show a high thermal stability with wide mesophase temperature ranges. For polymer P1 bearing only cholesteric LC monomers component, it shows a cholesteric phase, whereas others display a blue phase besides a cholesteric phase. The formation of the blue phase is based on the structures of the polymers and the produced biaxial helix. The glass transition temperature and isotropic temperature of the polymers decrease on heating cycle with increasing the content of M3 in the polymers. The specific rotation values of the polymers are temperature-sensitive. The reflection spectra of polymers P1-P6 show that the maximum reflected wavelengths shift to long wavelength with increasing the content of M3 in the polymer systems. The frequency and intensity of the bands change sharply at the temperature where cholesteric phase changes to blue phase, but they show a weak dependence on temperature in the blue phase. © 2013 © Taylor & Francis.


Li G.,Northeastern University China | Wang Y.,China Institute of Technology
Proceedings - 2013 International Conference on Cyber-Enabled Distributed Computing and Knowledge Discovery, CyberC 2013 | Year: 2013

The constrained capacity of wireless sensor nodes and harsh, unattended deploy environments make the data collected by sensor nodes usually unreliable. In this paper, we propose a sketch based anomaly detection scheme in order to detect the anomaly data values. It first partitions the whole sensor network into several clusters in which the cluster members are physically adjacent and data correlated. Then, the cluster header collects the count-min sketch of each cluster member and compares it with its own sketch in the form of kullback-leibler divergence. The experiment shows that the proposed anomaly detection scheme can provide a high detection accuracy ratio and a low false alarm ratio. © 2013 IEEE.


Ma J.-Z.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We point out that the CPL parametrization has a problem that the equation of state w(z) diverges in the far future, so that this model can only properly describe the past evolution but cannot depict the future evolution. To overcome such a difficulty, in this Letter we propose two novel parametrizations for dark energy, the logarithm form w(z)=w0+w1(ln(2+z)1+z-ln2) and the oscillating form w(z)=w0+w1(sin(1+z)1+z-sin(1)), successfully avoiding the future divergency problem in the CPL parametrization, and use them to probe the dynamics of dark energy in the whole evolutionary history. Our divergency-free parametrizations are proven to be very successful in exploring the dynamical evolution of dark energy and have powerful prediction capability for the ultimate fate of the universe. Constraining the CPL model and the new models with the current observational data, we show that the new models are more favored. The features and the predictions for the future evolution in the new models are discussed in detail. © 2011 Elsevier B.V.


Li H.,CAS Institute of High Energy Physics | Li H.,Chinese Academy of Sciences | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

The CPL parametrization is very important for investigating the property of dark energy with observational data. However, the CPL parametrization only respects the past evolution of dark energy but does not care about the future evolution of dark energy, since w(z) diverges in the distant future. In a recent paper [J.Z. Ma, X. Zhang, Phys. Lett. B 699 (2011) 233], a robust, novel parametrization for dark energy, w(z)=w0+w1(ln(2+z)/1+z-ln2), has been proposed, successfully avoiding the future divergence problem in the CPL parametrization. On the other hand, an oscillating parametrization (motivated by an oscillating quintom model) can also avoid the future divergence problem. In this Letter, we use the two divergence-free parametrizations to probe the dynamics of dark energy in the whole evolutionary history. In light of the data from 7-year WMAP temperature and polarization power spectra, matter power spectrum of SDSS DR7, and SN Ia Union2 sample, we perform a full Markov Chain Monte Carlo exploration for the two dynamical dark energy models. We find that the best-fit dark energy model is a quintom model with the EOS across -1 during the evolution. However, though the quintom model is more favored, we find that the cosmological constant still cannot be excluded. © 2011 Elsevier B.V.


Wang S.,Northeastern University China | Li Y.-H.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

It has been found in previous studies that, for the Supernova Legacy Survey three-year (SNLS3) data, there is strong evidence for the redshift evolution of color-luminosity parameter β. In this paper, using the three simplest dark energy models, i.e., the Λ-cold-dark-matter (ΛCDM) model, the wCDM model, and the Chevallier-Polarski-Linder model, we further explore the evolution of β and its effects on parameter estimation. In addition to the SNLS3 data, we also take into account the Planck distance priors data of the cosmic microwave background (CMB), as well as the latest galaxy clustering (GC) data extracted from SDSS DR7 and BOSS. We find that, for all the models, adding a parameter of β can reduce χmin2 by ∼36, indicating that β1=0 is ruled out at 6σ confidence levels. In other words, β deviates from a constant at 6σ confidence levels. This conclusion is insensitive to the dark energy models considered, showing the importance of considering the evolution of β in the cosmology fits. Furthermore, it is found that varying β can significantly change the fitting results of various cosmological parameters: using the SNLS3 data alone, varying β yields a larger Ωm for the ΛCDM model; using the SNLS3+CMB+GC data, varying β yields a larger Ωm and a smaller h for all the models. Moreover, we find that these results are much closer to those given by the CMB+GC data compared to the cases of treating β as a constant. This indicates that considering the evolution of β is very helpful for reducing the tension between supernova and other cosmological observations. © 2014 American Physical Society.


Li Y.-H.,Northeastern University China | Zhang J.-F.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

Dark energy might directly interact with cold dark matter. However, in such a scenario, an early-time large-scale instability occurs occasionally, which may be due to the incorrect treatment for the pressure perturbation of dark energy as a nonadiabatic fluid. To avoid this nonphysical instability, we establish a new framework to correctly calculate the cosmological perturbations in the interacting dark energy models. Inspired by the well-known parametrized post-Friedmann approach, the condition of the dark energy pressure perturbation is replaced with the relationship between the momentum density of dark energy and that of other components on large scales. By reconciling the perturbation evolutions on the large and small scales, one can complete the perturbation equations system. The large-scale instability can be successfully avoided and the well-behaved density and metric perturbations are obtained within this framework. Our test results show that this new framework works very well and is applicable to all the interacting dark energy models. © 2014 American Physical Society.


Li Y.-H.,Northeastern University China | Zhang J.-F.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

In this paper, we constrain the dimensionless Compton wavelength parameter B0 of f(R) gravity as well as the mass of sterile neutrino by using the cosmic microwave background observations, the baryon acoustic oscillation surveys, and the linear growth rate measurements. Since both the f(R) model and the sterile neutrino generally predict scale-dependent growth rates, we utilize the growth rate data measured in different wavenumber bins with the theoretical growth rate approximatively scale-independent in each bin. The employed growth rate data come from the peculiar velocity measurements at z=0 in five wavenumber bins, and the redshift space distortions measurements at z=0.25 and z=0.37 in one wavenumber bin. By constraining the f(R) model alone, we get a tight 95% upper limit of log10 B0<-4.1. This result is slightly weakened to log10 B0<-3.8 (at 2σ level) once we simultaneously constrain the f(R) model and the sterile neutrino mass, due to the degeneracy between the parameters of the two. For the massive sterile neutrino parameters, we get the effective sterile neutrino mass mν,sterileeff<0.62 eV (2σ) and the effective number of relativistic species Neff<3.90 (2σ) in the f(R) model. As a comparison, we also obtain mν,sterileeff<0.56 eV (2σ) and Neff<3.92 (2σ) in the standard ΛCDM model. © 2015 The Authors.


Li G.,Northeastern University China | Wang Y.,China Institute of Technology
Eurasip Journal on Wireless Communications and Networking | Year: 2013

Data aggregation is a very important method to conserve energy by eliminating the inherent redundancy of raw data in wireless sensor networks (WSNs). In this article, we developed an automatic auto regressive-integrated moving averagemodeling-based data aggregation scheme in WSNs. The main idea behind this scheme is to decrease the number of transmitted data values between sensor nodes and aggregators by utilizing time series prediction model. The proposed scheme can effectively save the precious battery energy of wireless sensor nodes while keeping the predicted data values of aggregators within application-defined error threshold. We show through experiments with real data that the predicted data values of our proposed scheme fit the real sensed data values very well and fewer messages are transmitted between sensor nodes and aggregators than the native data aggregation scheme. Furthermore, the characteristics of the proposed data aggregation scheme are also discussed in this article. © 2013 Li and Wang.


Dai S.-L.,Northeastern University China | Dai S.-L.,National University of Singapore | Lin H.,National University of Singapore | Ge S.S.,National University of Singapore
IEEE Transactions on Control Systems Technology | Year: 2010

This paper is concerned with the simultaneous stabilization of a collection of continuous-time linear time-invariant (LTI) plants whose feedback-control loops are closed via a shared digital communication network. Because of the limitation of communication capacity, only a limited number of controller-plant connections can be accommodated at any time instant. Therefore, it is necessary to carefully determine a scheduling policy so as to achieve a simultaneous stabilization for all these control loops. A sufficient condition on the existence of such a scheduling policy is presented for a collection of networked LTI systems with sampled- data controllers and uncertain network-induced delays. The proof for the schedulability condition is in a constructive way, which can also serve as a systematic method to design a scheduling policy. Finally, a scheduling-and-feedback-control codesign procedure is proposed for the simultaneous stabilization of the collection of networked LTI systems, and the effectiveness of the proposed codesign procedure is demonstrated with simulation results. © 2009 IEEE.


Li Y.-H.,Northeastern University China | Zhang J.-F.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

Dark energy can modify the dynamics of dark matter if there exists a direct interaction between them. Thus, a measurement of the structure growth, e.g., redshift-space distortions (RSDs), can provide a powerful tool to constrain the interacting dark energy (IDE) models. For the widely studied Q=3βHρde model, previous works showed that only a very small coupling [β∼O(10-3)] can survive in current RSD data. However, all of these analyses had to assume w>-1 and β>0 due to the existence of the large-scale instability in the IDE scenario. In our recent work [Phys. Rev. D 90, 063005 (2014)], we successfully solved this large-scale instability problem by establishing a parametrized post-Friedmann framework for the IDE scenario. So we, for the first time, have the ability to explore the full parameter space of the IDE models. In this work, we re-examine the observational constraints on the Q=3βHρde model within the parametrized post-Friedmann framework. By using the Planck data, the baryon acoustic oscillation data, the JLA sample of supernovae, and the Hubble constant measurement, we get β=-0.010-0.033+0.037 (1σ). The fit result becomes β=-0.0148-0.0089+0.0100 (1σ) once we further incorporate the RSD data in the analysis. The error of β is substantially reduced with the help of the RSD data. Compared with the previous results, our results show that a negative β is favored by current observations, and a relatively larger interaction rate is permitted by current RSD data. © 2014 American Physical Society.


Li Y.-H.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

Dark energy might interact with cold dark matter in a direct, nongravitational way. However, the usual interacting dark energy models (with constant w) suffer from some catastrophic difficulties. For example, the Qρc model leads to an early-time large-scale instability, and the Qρde model gives rise to the future unphysical result for cold dark matter density (in the case of a positive coupling). In order to overcome these fatal flaws, we propose in this paper an interacting dark energy model (with constant w) in which the interaction term is carefully designed to realize that Qρde at the early times and Qρc in the future, simultaneously solving the early-time superhorizon instability and future unphysical ρc problems. The concrete form of the interaction term in this model is Q= 3βHρdeρcρde+ρc, where β is the dimensionless coupling constant. We show that this model is actually equivalent to the decomposed new generalized Chaplygin gas (NGCG) model, with the relation β=-αw. We calculate the cosmological perturbations in this model in a gauge-invariant way and show that the cosmological perturbations are stable during the whole expansion history provided that β>0. Furthermore, we use the Planck data in conjunction with other astrophysical data to place stringent constraints on this model (with eight parameters), and we find that indeed β>0 is supported by the joint constraint at more than 1σ level. The excellent theoretical features and the support from observations all indicate that the decomposed NGCG model deserves more attention and further investigation. © 2014 American Physical Society.


Li Y.-H.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
European Physical Journal C | Year: 2011

In this paper we put forward a running coupling scenario for describing the interaction between dark energy and dark matter. The dark sector interaction in our scenario is free of the assumption that the interaction term Q is proportional to the Hubble expansion rate and the energy densities of dark sectors. We only use a time-variable coupling b(a) (with a the scale factor of the universe) to characterize the interaction Q. We propose a parametrization form for the running coupling b(a)=b0 a+be(1-a) in which the early-time coupling is given by a constant be, while today the coupling is given by another constant, b0. For investigating the feature of the running coupling, we employ three dark energy models, namely, the cosmological constant model (w=-1), the constant w model (w=w0), and the time-dependent w model (w(a)=w0+w1(1-a)). We constrain the models with the current observational data, including the type Ia supernova, the baryon acoustic oscillation, the cosmic microwave background, the Hubble expansion rate, and the X-ray gas mass fraction data. The fitting results indicate that a time-varying vacuum scenario is favored, in which the coupling b(z) crosses the noninteracting line (b=0) during the cosmological evolution and the sign changes from negative to positive. The crossing of the noninteracting line happens at around z=0.2-0.3, and the crossing behavior is favored at about 1σ confidence level. Our work implies that we should pay more attention to the time-varying vacuum model and seriously consider the phenomenological construction of a sign-changeable or oscillatory interaction between dark sectors. © 2011 Springer-Verlag/Società Italiana di Fisica.


Wu L.-B.,Northeastern University China | Wu L.-B.,University Of Science And Technology Liaoning | Yang G.-H.,Northeastern University China
Fuzzy Sets and Systems | Year: 2016

This paper considers the problem of adaptive fuzzy tracking control for a class of uncertain nonaffine nonlinear systems with mismatched external disturbances, parameter uncertainties, and nonsymmetric dead-zone inputs. Without the help of the dead-zone inverse function and by incorporating the implicit function theorem, both the adaptive state feedback tracking controller and the adaptive output feedback tracking controller based on high gain observer are designed by utilizing fuzzy logic systems (FLS) to approximate the appropriate nonlinear control input functions. A compounded disturbance is defined in terms of the external disturbance, parameter uncertainty, nonsymmetric dead-zone input, and approximation error of FLS. Under the condition that the upper bound of the compounded disturbance is unknown, novel adaptive laws are introduced to estimate and tune the unknown controller parameters on-line. Furthermore, on the basis of Lyapunov stability analysis, it is also proved that the presented control methods can guarantee that all the closed-loop system error signals are uniformly ultimately bounded. Finally, two simulation examples are provided to demonstrate efficiency of the proposed adaptive fuzzy tracking control approaches. © 2015 Elsevier B.V. All rights reserved.


Zhang J.-F.,Northeastern University China | Li Y.-H.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We show that involving a sterile neutrino species in the ΛCDM + r model can help relieve the tension about the tensor-to-scalar ratio r between the Planck temperature data and the BICEP2 B-mode polarization data. Such a model is called the ΛCDM + r + νs model in this paper. Compared to the ΛCDM + r model, there are two extra parameters, Neff and mν,sterileeff, in the ΛCDM + r + νs model. We show that in this model the tension between Planck and BICEP2 can be greatly relieved at the cost of the increase of ns. However, comparing with the ΛCDM + r + dns/d lnk model that can significantly reduce the tension between Planck and BICEP2 but also makes trouble to inflation due to the large running of the spectral index of the order 10-2 produced, the ΛCDM + r + νs model is much better for inflation. By including a sterile neutrino species in the standard cosmology, besides the tension with BICEP2, the other tensions of Planck with other astrophysical data, such as the H0 direct measurement, the Sunyaev-Zeldovich cluster counts, and the galaxy shear data, can all be significantly relieved. So, this model seems to be an economical choice. Combining the Planck temperature data, the WMAP-9 polarization data, and the baryon acoustic oscillation data with all these astrophysical data (including BICEP2), we find that in the ΛCDM + r + νs model ns=0.999 ± 0.011, r=0.21-0.05 + 0.04, Neff=3.95 ± 0.33 and mν,sterile eff = 0.51-0.13 +0.12eV. Thus, our results prefer δNeff>0 at the 2.7σ level and a nonzero mass of sterile neutrino at the 3.9σ level. © 2014 The Authors.


Shen Q.,Nanjing University of Aeronautics and Astronautics | Shen Q.,Yangzhou University | Jiang B.,Nanjing University of Aeronautics and Astronautics | Shi P.,University of Adelaide | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2014

In this paper, the cooperative adaptive fault tolerant fuzzy tracking control (CAFTFTC) problem of networked high-order multiagent with time-varying actuator faults is studied, and a novel CAFTFTC scheme is proposed to guarantee that all follower nodes asymptotically synchronize a leader node with tracking errors converging to a small adjustable neighborhood of the origin in spite of actuator faults. The leader node is modeled as a higher order nonautonomous nonlinear system. It acts as a command generator giving commands only to a small portion of the networked group. Each follower is assumed to have nonidentical unknown nonlinear dynamics, and the communication network is also assumed to be a weighted directed graph with a fixed topology. A distributed robust adaptive fuzzy controller is designed for each follower node such that the tracking errors are cooperative uniform ultimate boundedness (CUUB). Moreover, these controllers are distributed in the sense that the controller designed for each follower node only requires relative state information between itself and its neighbors. The adaptive compensation term of the optimal approximation errors and external disturbances is adopted to reduce the effects of the errors and disturbances, which removes the assumption that the upper bounds of unknown function approximation errors and disturbances should be known. Analysis of stability and parameter convergence of the proposed algorithm are conducted that are based on algebraic graph theory and Lyapunov theory. Comparing with results in the literature, the CAFTFTC scheme can minimize the time delay between fault occurrence and accommodation and reduce its adverse effect on system performance. In addition, the FTC scheme requires no additional fault isolation model, which is necessary in the traditional active FTC scheme. Finally, an example is provided to validate the theoretical results. © 2014 IEEE.


Li G.,Northeastern University China | Wang Y.,China Institute of Technology
Proceedings - 2012 IEEE 12th International Conference on Computer and Information Technology, CIT 2012 | Year: 2012

The constrained capacity of wireless sensor nodes and harsh, unattended deploy environments make the data collected by sensor nodes usually unreliable. In this paper, we propose a Differential Kullback-Leibler Divergence based anomaly detection scheme with the goal of detecting anomaly data values. It first partitions the whole sensor network into several clusters in which the sensors in each cluster are physically close to each other and have the similar sensed values. Then, the cluster header detects the outliers within the current cluster using Kullback-Leibler Divergence in a differential manner. The proposed scheme is lightweight and energy efficient than the existing detection scheme while maintaining the similar detection performance in terms of detection accuracy ratio and false alarm ratio. © 2012 IEEE.


Chen S.,Northeastern University China | Hai X.,Northeastern University China | Xia C.,Northeastern University China | Chen X.-W.,Northeastern University China | Wang J.-H.,Northeastern University China
Chemistry - A European Journal | Year: 2013

We report the first pyrrole-ring surface-functionalized graphene quantum dots (p-GQDs) prepared by a two-step hydrothermal approach under microwave irradiation in an ammonia medium. The most distinct feature of the functionalized GQDs is that both the excitation and emission wavelengths fall into the visible-light region. The p-GQDs are excited by visible light at λex 490nm (2.53eV) to emit excitation-independent photoluminescence at a maximum wavelength of λem 550nm. This is thus far the longest emission wavelength reported for GQDs. Stable photoluminescence is achieved at pH4-10 with an ionic strength of 1.2mol L -1 KCl. These features make the p-GQDs excellent probes for bio-imaging and bio-labeling, which is demonstrated by imaging live HeLa cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Tian J.,Northeastern University China
Energy Procedia | Year: 2011

[Purpose] This paper explains the basic theory and research methods of ecological security based on the basic concept of ecological security. Qinhuangdao City is the study area, the index system of its ecological security assessment was constructed on the basis of the pressure - state - response conceptual model, and its ecological security was evaluated by comprehensive index method. The evaluation result is that the ecological security index of Qinhuangdao is 0.633, and it is in the lower bound of the relatively safer state. At present, the main ecological problems are water shortage, water pollutions, large quantity of gaseous pollutants emission from heavy industry enterprises, inadequate protection of natural reserves, and insufficient investments in environmental protection. Some targeted countermeasures for strengthening regional ecological security management are proposed as following: establishing ecological security early warning system, developing and utilizing water resources rationally to improve water utilization efficiency, strengthening the marine environmental protection to ensure the security of marine environment, reducing sulfur dioxide emission volume by improving air quality through an effective way, and implementing ecological restoration project to improve the ecological carrying capacity. The ecology of Qinhuangdao would move to a safer ecological level through these channels. © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of International Materials Science Society.


Zhang J.-F.,Northeastern University China | Li Y.-H.,Northeastern University China | Zhang X.,Northeastern University China | Zhang X.,Peking University
The European Physical Journal C | Year: 2014

Since the B-mode polarization of the cosmic microwave background (CMB) was detected by the BICEP2 experiment and an unexpectedly large tensor-to-scalar ratio, (Formula presented.), was found, the base standard cosmology should at least be extended to the 7-parameter (Formula presented.)CDM+(Formula presented.) model. In this paper, we consider the extensions to this base (Formula presented.)CDM+(Formula presented.) model by including additional base parameters relevant to neutrinos and/or other neutrino-like relativistic components. Four neutrino cosmological models are considered, i.e., the (Formula presented.)CDM+(Formula presented.)+(Formula presented.), (Formula presented.)CDM+(Formula presented.)+(Formula presented.), (Formula presented.)CDM+(Formula presented.)+(Formula presented.)+(Formula presented.), and (Formula presented.)CDM+(Formula presented.)+(Formula presented.)+(Formula presented.) models. We combine the current data, including the Planck temperature data, the WMAP 9-year polarization data, the baryon acoustic oscillation data, the Hubble constant direct measurement data, the Planck Sunyaev-Zeldovich cluster counts data, the Planck CMB lensing data, the cosmic shear data, and the BICEP2 polarization data, to constrain these neutrino cosmological models. We focus on the constraints on the parameters (Formula presented.), (Formula presented.), and (Formula presented.). We also discuss whether the tension on (Formula presented.) between Planck and BICEP2 can be relieved in these neutrino cosmological models. © 2014 The Author(s).


Sun Q.,Northeastern University China | Zhou J.,Northeastern University China | Guerrero J.M.,University of Aalborg | Zhang H.,Northeastern University China
IEEE Transactions on Power Electronics | Year: 2015

With the fast proliferation of single-phase distributed generation (DG) units and loads integrated into residential microgrids, independent power sharing per phase and full use of the energy generated by DGs have become crucial. To address these issues, this paper proposes a hybrid microgrid architecture and its power management strategy. In this microgrid structure, a power sharing unit (PSU), composed of three single-phase back-to-back (SPBTB) converters, is proposed to be installed at the point of common coupling. The aim of the PSU is mainly to realize the power exchange and coordinated control of load power sharing among phases, as well as to allow full utilization of the energy generated by DGs. Meanwhile, the method combining the modified adaptive backstepping-sliding mode control approach and droop control is also proposed to design the SPBTB system controllers. With the application of the proposed PSU and its power management strategy, the loads among different phases can be properly supplied and the energy can be fully utilized, as well as obtaining better load sharing. Simulation and experimental results are provided to demonstrate the validity of the proposed hybrid microgrid structure and control. © 1986-2012 IEEE.


Yu H.-M.,Northeastern University China | Yu H.-M.,University Of Science And Technology Liaoning | Song H.,University Of Science And Technology Liaoning | Chen M.-L.,Northeastern University China
Talanta | Year: 2011

A novel adsorbent-silica gel bound dithizone (H2Dz-SG) was prepared and used as solid-phase extraction of copper from complex matrix. The H2Dz-SG is investigated by means of FT-IR spectra and the SEM images, demonstrating the bonding of dithizone. The H2Dz-SG quantitatively adsorb copper ions, and the retained copper is afterwards collected by elution of 10% (v/v) nitric acid. An on-line flow injection solid-phase extraction procedure was developed for trace copper separation and preconcentration with detection by flame atomic spectrometry. By loading 5.4 mL of sample solution, a liner range of 0.5-120 μg L-1, an enrichment factor of 42.6, a detection limit of 0.2 μg L-1 and a precision of 1.7% RSD at the 40 μg L-1 level (n = 11) were obtained, along with a sampling frequency of 47 h-1. The dynamic sorption capacity of H 2Dz-SG to Cu2+ was 0.76 mg g-1. The accuracy of the proposed procedure was evaluated by determination of copper in reference water sample. The potential applications of the procedure for extraction of trace copper were successfully accomplished in water samples (tap, rain, snow, sea and river). The spiking recoveries within 91-107% are achieved. © 2011 Elsevier B.V. All rights reserved.


Li H.,CAS Institute of High Energy Physics | Li H.,CAS National Astronomical Observatories | Zhang X.,Northeastern University China | Zhang X.,Peking University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

In this Letter, we report the results of constraining the dynamical dark energy with a divergence-free parameterization, in the presence of spatial curvature and massive neutrinos, with the 7-yr WMAP temperature and polarization data, the power spectrum of LRGs derived from SDSS DR7, the Type Ia supernova data from Union2 sample, and the new measurements of H 0 from HST, by using a MCMC global fit method. Our focus is on the determinations of the spatial curvature, Ω k, and the total mass of neutrinos, ∑m ν, in such a dynamical dark energy scenario, and the influence of these factors to the constraints on the dark energy parameters, w0 and wa. We show that Ω k and ∑m ν can be well constrained in this model; the 95% CL limits are: -0.0153<Ω k<0.0167 and ∑m ν<0.56eV. Comparing to the case in a flat universe, we find that the error in w0 is amplified by 25.51%, and the error in wa is amplified by 0.14%; comparing to the case with a zero neutrino mass, we find that the error in w0 is amplified by 12.24%, and the error in wa is amplified by 1.63%. © 2012 Elsevier B.V.


Tian Y.,Northeastern University China | Li Z.,Shenyang Institute of Engineering
Journal of Iron and Steel Research International | Year: 2012

Warm deformation tests were performed using a kind of tubby heater. The microstructures and mechanical properties of an Fe-C-Mn-Si multiphase steel resulting from different warm deformation temperatures were investigated by using LOM (light optical microscopy), SEM and XRD. The results indicated that the microstructure containing polygonal ferrite, granular bainite and a significant amount of the stable retained austenite can be obtained through hot deformation and subsequent austempering. Warm deformation temperature affects the mechanical properties of the hot rolled TRIP steels. Ultimate tensile strength balance reached maximum (881 MPa) when the specimen was deformed at 250°C, and the total elongation and strength-ductility reached maximum (38% and 28614 MPa · %, respectively) at deforming temperature of 100°C. Martensite could nucleate when austenite was deformed above M 3, because mechanical driving force compensates the decrease of chemical driving force. The TRIP effect occurs in the Fe-C-Mn-Si multiphase steel at deforming temperature ranging from 15 to 350°C. The results of the effects of warm deformation on the mechanical properties of the Fe-C-Mn-Si multiphase steel can provide theoretical basis for the applications and the warm working of the hot rolled TRIP sheet steels in industrial manufacturing. © 2012 Central Iron and Steel Research Institute.


Xie X.,Nanjing University of Posts and Telecommunications | Xie X.,Huazhong University of Science and Technology | Yang D.,Northeastern University China | Ma H.,Northeastern University China
IEEE Transactions on Fuzzy Systems | Year: 2014

This paper is concerned with the design of observer for discrete-time nonlinear systems in the Takagi-Sugeno (T-S) fuzzy form. Under the framework of multi-instant homogenous matrix polynomials, a novel fuzzy observer and a new Lyapunov function, which are homogenous polynomially parameter-dependent on both the current-time normalized fuzzy weighting functions and the m-steps past-time normalized fuzzy weighting functions, are proposed for conceiving less conservative observer design conditions. Since the algebraic properties of both the current-time normalized fuzzy weighting functions and the m-steps past-time normalized fuzzy weighting functions are fully considered, the relaxation quality of the fuzzy observer design of discrete-time T-S fuzzy systems is significantly improved. In particular, some existing fuzzy Lyapunov functions and fuzzy observers are special cases of the Lyapunov function and the fuzzy observer given in this paper, respectively. Finally, a numerical example is provided to illustrate the effectiveness of the proposed approach. © 2014 IEEE.


Bi Z.,Indiana University - Purdue University Fort Wayne | Xu L.D.,CAS Institute of Computing Technology | Xu L.D.,Shanghai JiaoTong University | Xu L.D.,Hefei University of Technology | And 2 more authors.
IEEE Transactions on Industrial Informatics | Year: 2014

Design and operation of a manufacturing enterprise involve numerous types of decision-making at various levels and domains. A complex system has a large number of design variables and decision-making requires real-time data collected from machines, processes, and business environments. Enterprise systems (ESs) are used to support data acquisition, communication, and all decision-making activities. Therefore, information technology (IT) infrastructure for data acquisition and sharing affects the performance of an ES greatly. Our objective is to investigate the impact of emerging Internet of Things (IoT) on ESs in modern manufacturing. To achieve this objective, the evolution of manufacturing system paradigms is discussed to identify the requirements of decision support systems in dynamic and distributed environments; recent advances in IT are overviewed and associated with next-generation manufacturing paradigms; and the relation of IT infrastructure and ESs is explored to identify the technological gaps in adopting IoT as an IT infrastructure of ESs. The future research directions in this area are discussed. © 2012 IEEE.


Hou W.,Northeastern University China | Guo L.,Northeastern University China | Wei X.,University of California at Riverside
Journal of Lightwave Technology | Year: 2011

Fueled by the growing resource crisis and potential economic incentives, significant research attention has recently been devoted to improving the power efficiency of IP over Wavelength-Division-Multiplexing (WDM) networks. Previous works on power savings in IP over WDM networks have required explicit knowledge of the traffic between each network node pair and the resource assignment of each fiber link. However, it is difficult to accurately estimate this information in live networks due to the inherent features of IP traffic, e.g., bursts, unpredictability and variability. Furthermore, the number of ports consumed in Optical Cross-Connects (OXCs) trends to grow due to the use of traffic grooming and optical bypasses for power savings. Therefore, it is necessary to achieve joint power efficiency and port savings in live IP over WDM networks where the traffic between each network node pair and resource assignment of each fiber link are not known in advance. Since the problem of grooming, routing and wavelength/waveband assignment is NP-hard, a new heuristic approach, the Robust and Integrated Grooming (RIG) algorithm, is proposed in this paper. RIG uses a novel metric, a power ratio defined by the power consumed over the power saved, to evaluate the power efficiency. By determining the Traffic Distribution Vector (TDV) with the lowest power ratio using the Minimizing Power Ratio First (MPRF) method, the previously unknown information can be acquired. By performing traffic matrix transformations, we construct a green optical virtual topology to groom connection demands into established lightpaths using Hybrid Grooming Schemes (HGSs) for power efficiency and waveband switching for port savings. The simulation results demonstrate that RIG can, on average, achieve power efficiency and port savings of 15% and 32%, respectively, compared to state-of-the-art robust grooming methods. To the best of our knowledge, this paper is the first work addressing robust and integrated grooming for power- and port-cost-efficient design in IP over WDM networks. © 2011 IEEE.


Xu J.,Northeastern University China | Zhang Z.,Advanced Digital science Center | Xiao X.,Nanyang Technological University | Yang Y.,Advanced Digital science Center | Yu G.,Northeastern University China
Proceedings - International Conference on Data Engineering | Year: 2012

Differential privacy (DP) is a promising scheme for releasing the results of statistical queries on sensitive data, with strong privacy guarantees against adversaries with arbitrary background knowledge. Existing studies on DP mostly focus on simple aggregations such as counts. This paper investigates the publication of DP-compliant histograms, which is an important analytical tool for showing the distribution of a random variable, e.g., hospital bill size for certain patients. Compared to simple aggregations whose results are purely numerical, a histogram query is inherently more complex, since it must also determine its structure, i.e., the ranges of the bins. As we demonstrate in the paper, a DP-compliant histogram with finer bins may actually lead to significantly lower accuracy than a coarser one, since the former requires stronger perturbations in order to satisfy DP. Moreover, the histogram structure itself may reveal sensitive information, which further complicates the problem. Motivated by this, we propose two novel algorithms, namely Noise First and Structure First, for computing DP-compliant histograms. Their main difference lies in the relative order of the noise injection and the histogram structure computation steps. Noise First has the additional benefit that it can improve the accuracy of an already published DP-complaint histogram computed using a naiive method. Going one step further, we extend both solutions to answer arbitrary range queries. Extensive experiments, using several real data sets, confirm that the proposed methods output highly accurate query answers, and consistently outperform existing competitors. © 2012 IEEE.


Huang M.,Northeastern University China | Song M.,Northeastern University China | Lee L.H.,National University of Singapore | Lee L.H.,Shanghai Maritime University | Ching W.K.,University of Hong Kong
International Journal of Production Economics | Year: 2013

This paper investigates optimal strategies of a closed-loop supply chain (CLSC) with dual recycling channel, within which the manufacturer sells products via the retailer in the forward supply chain, while the retailer and the third party competitively collect used products in the reverse supply chain. Based on game theory, we characterize the supply chain performance in terms of the pricing decisions and the recycling strategies for both the decentralized and the centralized channel scenarios. By comparing this work with the existing optimal strategies of the CLSC with single recycling channel (the retailer or the third party), we derive the parameter domain which is defined as the set of competing intensities for which the CLSC with dual recycling channel outperforms the CLSC with single recycling channel from the perspectives of the manufacturer and the consumers, respectively. Moreover, we give some suggestions, which will present paramount social value, to the macro-control policy making by exhaustive numerical analysis. The results in this paper can be used as a reference for choosing recycling model, the single recycling channel or the dual recycling channel, for collecting used products. © 2013 Elsevier B.V.


Pan Q.-K.,Northeastern University China | Pan Q.-K.,Liaocheng University | Wang L.,Tsinghua National Laboratory for Information Sciences and Technology | Mao K.,Northeastern University China | And 2 more authors.
IEEE Transactions on Automation Science and Engineering | Year: 2013

This paper aims to provide a solution method for the real-world hybrid flowshop scheduling problem resulting from a steelmaking process, which has important applications in modern iron and steel industry. We first present a mixed integer mathematic model based on a comprehensive investigation. Then, we develop a heuristic method and two improvement procedures for a given schedule based on the problem-specific characteristics. Finally, we propose an effective artificial bee colony (ABC) algorithm with the job-permutation-based representation for solving the scheduling problem. The proposed ABC algorithm incorporates the heuristic and improvement procedures as well as new characteristics including a neighboring solution generation method and two enhanced strategies. To evaluate the proposed algorithm, we present several adaptations of other well-known and recent metaheuristics to the problem and conduct a serial of experiments with the instances generated according to real-world production process. The results show that the proposed ABC algorithm is more effective than all other adaptations after comprehensive computational comparisons and statistical analysis. © 2004-2012 IEEE.


Grant
Agency: Department of Health and Human Services | Branch: | Program: STTR | Phase: Phase I | Award Amount: 141.07K | Year: 2011

DESCRIPTION (provided by applicant): Project Summary/Abstract Post-traumatic Stress Disorder (PTSD) is recognized by the NIMH, the Department of Defense, and the Veterans' Administration as a major medical issue. Recent studies indicate that the incidence of PTSD among Iraq and Afghanistan veterans is 20% and may reach 35%, a rate far higher than in the general population. PTSD is not only an illness that affects military personnel; almost eight million Americans suffer from this disorder and it ranksamong the most common psychiatric conditions. Current drug therapies for PTSD rely on repurposed antidepressants that are at best only modestly effective, produce undesirable side effects, and have recognized compliance issues. A new approach to pharmacotherapy is needed for significant improvement in clinical outcomes. Arginine Vasopressin (AVP) 1a receptor antagonists represent a potential new approach for the treatment of PTSD; both clinical and preclinical observations support this view. Elevated levels of AVP associated with significant alterations in HPA axis function represent a recently identified, prominent clinical sign in veterans with PTSD. Alterations in HPA axis function are widely documented in PTSD patients. In a newly developed model of predatory fear conditioning, we have shown using fMRI that rats exposed to a natural predator, a ferret, while experiencing the taste of sucrose exhibit a hyperarousal pattern of brain activity in the limbic cortex and hippocampus in response to the taste ofsucrose weeks later. Indeed, the brain activity associated with the memory is far greater than that seen during the initial exposure to the predator. A similar pattern of hyperarousal in fear circuits also is seen in PTSD. Importantly, treatment with a highly selective, orally active V1a receptor antagonist from Azevan Pharmaceuticals blocked the hyperarousal when the traumatic memory was triggered by exposure to the conditioned stimulus, i.e., the taste of sucrose. Collectively, these observations providea strong basis for the development of vasopressin 1a antagonists as an innovative pharmacotherapy for PTSD. This proposal will use a unique predatory fear conditioning paradigm as a preclinical model to test the feasibility of using novel V1a antagonistsas a potential new pharmacotherapy for PTSD. The model will be used to extend preliminary findings that showed that a novel, orally active vasopressin 1a receptor antagonist effectively blocked the hyperarousal pattern of brain activity associated with thetraumatic memory triggered by exposure to sucrose. Positive results in the proposed studies will establish the basis for Phase II studies that will provide more in-depth preclinical assessments of the V1a antagonist approach for treating PTSD. . PUBLIC HEALTH RELEVANCE: Project Narrative Post-traumatic Stress Disorder (PTSD) is recognized by the National Institute of Mental Health, the Department of Defense, and the Veterans' Administration as a major medical issue. Current drug therapies for PTSD rely on repurposed antidepressants that are at best only modestly effective, produce undesirable side effects, and have recognized compliance issues. A new approach to pharmacotherapy is needed for significant improvement in clinical outcomes. ArginineVasopressin (AVP) 1a receptor antagonists represent a potential new approach for the treatment of PTSD based on clinical and preclinical observations. This proposal will use a unique predatory fear conditioning paradigm as a preclinical model to test thefeasibility of using novel V1a antagonists as a potential new pharmacotherapy for PTSD.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 149.99K | Year: 2015

ABSTRACT: LongShortWay Inc and NorthEastern University propose new feature clustering methods that improve performance of motion imagery classifiers. Developed algorithms will be demonstrated on AFRL Minor Area Motion Imagery (MAMI) data; BENEFIT: Enhanced classifier performance, robust feature selection


FRAMINGHAM, MA--(Marketwired - December 05, 2016) - CIO -- the executive-level tech media brand providing insight into business technology leadership -- and Northeastern University's D'Amore-McKim School of Business are delighted to announce a strategic partnership that includes two new executive education programs for technology executives: MBA Fundamentals for Tech Professionals and Beyond the MBA: Insights for Tech Executives (click to tweet). The first pair of intensive, four-day programs will be offered in the spring of 2017. "Businesses today expect their technology executives to lead them into the future, and that means they need to be well-versed in business strategy and all the disciplines that drive an organization," said Hugh Courtney, Dean of Northeastern University's D'Amore-McKim School of Business. "Both of these new programs achieve that goal, from fundamentals through the more advanced Beyond the MBA course." D'Amore-McKim School of Business Professor Samina Karim, a leading expert in corporate strategy and innovation, is faculty director for the CIO programs. She designed the curricula to provide tech leaders with the business principles and acumen to drive competitive advantage for their organizations in this era of business disruption. "These courses will fill a knowledge gap among our audience and provide deep dives into business issues with interactive problem solving that participants can begin to apply right away at their organizations," said Adam Dennison, SVP and Publisher of CIO. "We chose to partner with Northeastern because of their innovative culture and faculty expertise. These programs can offer a career-enhancing opportunity to the tech leaders we serve." MBA Fundamentals for Tech Professionals The MBA Fundamentals program is designed to give attendees a working understanding in the concepts that drive all business functions, from business strategy and innovation to accounting, finance, operations, and marketing. Attendees will develop a firsthand viewpoint of how colleagues in all these functions think and work, allowing them to speak their language and intrinsically understand their concerns -- greatly increasing effectiveness and perspective on the job. MBA Fundamentals will be offered May 8-11, 2017 and September 19-22, 2017 at Northeastern University on Huntington Avenue in Boston. Beyond the MBA: Insights for Tech Executives The Beyond the MBA program assumes some business background and focuses specifically on how technology executives can best lead their companies through disruption and change. Courses focus on transformation, analytics, metrics, acquisitions and leadership. Cases, discussions and teamwork projects will dive into the strategies and frameworks for transforming entire organizations through technology. Beyond the MBA will be offered June 5-8, 2017 and November 14-17, 2017 at Northeastern University on Huntington Avenue in Boston. All professionals are welcome to the MBA Fundamentals course. Participants of the Beyond the MBA course are typically senior executives at the level of director and above. While designed for technology professionals and executives, both programs are open to those of other disciplines as well. A discounted, early bird rate is being offered for both programs. Please visit http://events.cio.com/Northeastern for more information on registration and pricing. Additional aspects of the partnership will unfold in the coming months. Registration Information To learn more about the programs or to register to attend, visit http://events.cio.com/Northeastern or email: corpprograms@northeastern.edu. To sponsor an activity with program participants, contact Adam Dennison, SVP & General Manager, IDG Events & Publisher, CIO, at adennison@cio.com. About CIO CIO from IDG is the premier content and community resource for information technology executives and leaders thriving and prospering in this fast-paced era of IT transformation in the enterprise. The award-winning CIO portfolio -- CIO.com, CIO executive programs, CIO Strategic Marketing Services, CIO Forum on LinkedIn, CIO Executive Council and CIO primary research -- provides business technology leaders with analysis and insight on information technology trends and a keen understanding of IT's role in achieving business goals. Additionally, CIO provides opportunities for IT solution providers to reach this executive IT audience. The CIO Executive Council is a professional organization of CIOs created to serve as an unbiased and trusted peer advisory group. CIO is published by IDG Enterprise, a subsidiary of IDG. Company information is available at http://www.idgenterprise.com/. Follow CIO on Twitter: @CIOonline @CIOevents Follow IDG Enterprise on Twitter: @IDGEnterprise Follow CIO on LinkedIn Follow CIO on Facebook About IDG IDG connects the world of tech buyers with insights, intent and engagement. IDG is the world's largest media, data and marketing services company that activates and engages the most influential technology buyers. Our premium brands, including CIO®, Computerworld®, PCWorld® and Macworld®, engage the most powerful audience of technology buyers providing essential guidance on the evolving technology landscape. Our global data intelligence platform activates purchasing intent, powering our clients' success. IDG Marketing Services creates custom content with marketing impact across video, mobile, social and digital. We execute complex campaigns that fulfill marketers' global ambitions seamlessly with consistency that delivers results and wins awards. IDG is the #1 tech media company in the world, per comScore.* About the D'Amore-McKim School of Business Northeastern University's D'Amore-McKim School of Business offers a unique model of business education that purposely blends innovative classroom learning with real-world business application. Our students explore cutting-edge theory with professors, fusing knowledge with learning experiences that include cooperative education or corporate residency, study abroad, and community service. Similarly, our resulting connections with the corporate world influence our research agendas, which, in turn, shape innovative new business practice. This synergy enables our students to become successful business leaders who are both thinkers and doers, and thus highly qualified to think critically and leave their mark on the global business world. Founded in 1922, the D'Amore-McKim School of Business at Northeastern University is situated in the heart of Boston, a vibrant hub of business and technology. At the undergraduate level, both the BS in Business Administration and the BS in International Business programs offer students the opportunity to develop into highly motivated business leaders. Graduate students can choose from several different full-time and part-time MBA and MS programs designed to enable motivated professionals to accelerate their success in business. D'Amore-McKim executive and corporate programs provide tailored business education needed to develop leaders, build teams, and achieve strategic goals. The school is committed to embedding a global mindset into all of these programs, as well as in its research and outreach activities. Follow D'Amore-McKim on Twitter Follow D'Amore-McKim on Facebook Follow D'Amore-McKim on LinkedIn Follow D'Amore-McKim on Instagram About Northeastern University A private University founded in 1898, Northeastern University has emerged as one of the most dynamic universities in the country over the past decade and has evolved into a U.S. News & World Report 'Top-40' National University. The University is a leader in worldwide experiential learning and interdisciplinary research focused on innovation, entrepreneurship, and globalization. Northeastern enrolls nearly 20,000 students across 116 undergraduate majors and concentrations and 189 graduate programs, ranging from doctoral programs to graduate certificates, in nine schools and colleges, as well as select advanced degrees at the regional campuses in Charlotte, Silicon Valley, Seattle, Toronto, Canada.


Zheng B.-C.,Nanjing University of Information Science and Technology | Zheng B.-C.,Northeastern University China | Yang G.-H.,Northeastern University China
Nonlinear Dynamics | Year: 2013

This paper is concerned with the robust quantized feedback stabilization problem for a class of uncertain nonlinear large-scale systems with dead-zone nonlinearity in actuator devices. It is assumed that state signals of each subsystem are quantized and the quantized state signals are transmitted over a digital channel to the controller side. Combined with a proposed discrete on-line adjustment policy of quantization parameters, a decentralized sliding mode quantized feedback control scheme is developed to tackle parameter uncertainties and dead-zone input nonlin-earity simultaneously, and ensure that the system trajectory of each subsystem converges to the corresponding desired sliding manifold. Finally, an example is given to verify the validity of the theoretical result. © Springer Science+Business Media Dordrecht 2012.


Wei L.,China National Institute of Standardization | Chen Z.,Northeastern University China | Li J.,CAS Institute of Policy and Management
Information Sciences | Year: 2011

Not only different databases but two classes of data within a database can also have different data structures. SVM and LS-SVM typically minimize the empirical φ-risk; regularized versions subject to fixed penalty (L 2 or L1 penalty) are non-adaptive since their penalty forms are pre-determined. They often perform well only for certain types of situations. For example, LS-SVM with L2 penalty is not preferred if the underlying model is sparse. This paper proposes an adaptive penalty learning procedure called evolution strategies (ES) based adaptive Lp least squares support vector machine (ES-based Lp LS-SVM) to address the above issue. By introducing multiple kernels, a Lp penalty based nonlinear objective function is derived. The iterative re-weighted minimal solver (IRMS) algorithm is used to solve the nonlinear function. Then evolution strategies (ES) is used to solve the multi-parameters optimization problem. Penalty parameterp, kernel and regularized parameters are adaptively selected by the proposed ES-based algorithm in the process of training the data, which makes it easier to achieve the optimal solution. Numerical experiments are conducted on two artificial data sets and six real world data sets. The experiment results show that the proposed procedure offer better generalization performance than the standard SVM, the LS-SVM and other improved algorithms. © 2011 Elsevier Inc. All rights reserved.


Lu L.,Northeastern University China | Heemels W.P.M.H.,TU Eindhoven | Bemporad A.,IMT Institute for Advanced Studies Lucca
Proceedings of the IEEE Conference on Decision and Control | Year: 2011

Explicit model predictive controllers computed exactly by multi-parametric optimization techniques often lead to piecewise affine (PWA) state feedback controllers with highly complex and irregular partitionings of the feasible set. In many cases complexity prohibits the implementation of the resulting MPC control law for fast or large-scale system. This paper presents a new approach to synthesize low-complexity PWA controllers on regular partitionings that enhance fast on-line implementation with low memory requirements. Based on a PWA control-Lyapunov function, which can be obtained as the optimal cost for a constrained linear system corresponding to a stabilizing MPC setup, the synthesis procedure for the low-complexity control law boils down to local linear programming (LP) feasibility problems, which guarantee stability, constraint satisfaction, and certain performance requirements. Initially, the PWA controllers are computed on a fixed regular partitioning. However, we also present an automatic refinement procedure to refine the partitioning where necessary in order to satisfy the design specifications. A numerical example show the effectiveness of the novel approach. © 2011 IEEE.


Li S.,Northeastern University China | Dai J.S.,Tianjin University | Dai J.S.,King's College London
Journal of Mechanisms and Robotics | Year: 2012

This paper presents a new way of structure composition of single-driven metamorphic mechanisms to develop a systematic and modularized structure synthesis methodology of metamorphic mechanisms based on augmented Assur groups (AAGs). Planar metamorphic mechanisms can hence be constructed based on the developed AAGs by applying the structure composition rule of general planar mechanisms formed by Assur groups (AGs). First, the one-mobility AAGs are introduced based on class II and class III AGs; the structure formulation and composition methodology of planar metamorphic mechanisms are then proposed based on the AAGs, and the basic problems including mobility and synthesis of constrained metamorphic working mobility-configuration are investigated. This leads to the investigation of the degenerated equivalent AGs of AAGs in the metamorphic process and the corresponding kinematic characteristics, providing references for kinematic synthesis of metamorphic mechanisms. Further, a typical spatial metamorphic group is introduced based on the concept of AAGs, and the structure formation and composition of spatial metamorphic mechanisms are presented. Examples show that both planar and spatial metamorphic mechanisms can be constructed by utilizing the one-mobility blocks extended from the AGs. © 2012 American Society of Mechanical Engineers.


Sun W.,Northeastern University China | Zhang F.,Shanghai JiaoTong University
Energy | Year: 2016

Hot charging of continuous cast steel billets is usually considered an effective method for recovering heat. However, for certain grades of steel, the hot charging process may affect the steel surface quality. To overcome this issue, the billet is commonly cooled down before rolling, resulting in substantial heat loss. Thus, the recovery of useful waste heat without affecting steel quality is an important research topic. In this study, the design of a flash power system driven by the process heat of continuous casting grade steel billet is proposed. The influences of shunted water temperature and flash pressure on exergy recovery rate are studied via the thermodynamic methods. Moreover, a case study based on actual data is analyzed to verify the thermodynamic results and the energy recovery of the proposed system. The results indicate that the system exergy recovery rate increases with increasing shunted water temperature. Keeping the shunted temperature unchanged the exergy recovery rate firstly increases and later decreases with increasing flash pressure. At a fixed shunt temperature, an optimum flash pressure exists. At the maximum exergy recovery rate the net output power of the studied plant is 6361 kW, a value that greatly reduces the need for purchased electricity. © 2016 Elsevier Ltd


Zheng B.-C.,Nanjing University of Information Science and Technology | Yang G.-H.,Northeastern University China
ISA Transactions | Year: 2013

In this paper, an H2 control design for linear uncertain systems with input quantization in the presence of more general encoder/decoder mismatch is investigated. The construction of the control law includes two parts: linear part and nonlinear part. The gain of the linear part is derived from linear matrix inequalities (LMIs), and the linear part of the control law is designed for achieving the H2 performance against system characteristic matrix uncertainty and encoder/decoder mismatch. The nonlinear part is designed to eliminate the influence of external disturbance and quantization error. Finally, examples are provided to illustrate the effectiveness of the proposed method. © 2013 ISA.


Sui S.,Shanghai JiaoTong University | Ma L.,Northeastern University China | Zhai Y.,Northeastern University China
Journal of Power Sources | Year: 2011

Unitized regenerative fuel cells (URFCs) have become more attractive for some time due to its potentially wide energy storage application such as in fields of space and renewable energy. In this study, TiC supported Pt-Ir electrocatalysts (Pt-Ir/TiC) for oxygen electrode in URFCs were synthesized, respectively, by chemical reduction process and plasma reduction process. Their physical and electrochemical properties are characterized and compared using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammogram (CV), potentiostatic technique, and electrochemical impedance spectroscopy (EIS). The results from XRD, XPS and TEM demonstrate that the plasma process gives a finer metal crystals and higher metal dispersion on the TiC support. The CV, polarization, potentiostatic and EIS results show that the Pt-Ir/TiC electrocatalyst prepared by the plasma reduction process is obviously more active than that by the chemical reduction process, in agreement with the above metal-dispersion observations. The plasma process is a promising way for the preparation of supported electrocatalysts. © 2011 Elsevier B.V. All rights reserved.


Yongqiang L.,Northeastern University China | Dawei Z.,Shanghai JiaoTong University
Composite Structures | Year: 2011

Geometrically nonlinear forced vibrations of the symmetric rectangular honeycomb sandwich panels with the four edges simply supported and one surface affected by the water are investigated in this paper using the homotopy analysis method (HAM). The honeycomb core of hexagonal cells is modeled as a thick layer of orthotropic material whose physical and mechanical properties are determined using the Gibson correlations. The effect of water acting on honeycomb panels can be described as added mass, additional damping and additional stiffness coefficients which are obtained by the semi-analytical fluid pressures. The basic formulation of nonlinear forced vibrations has been developed base on the third-order shear deformation plate theory and Green Lagrange nonlinear strain-displacement relation. The equilibrium equations have been obtained using the Hamilton's principle. Effects of water velocity, height and height ratio on the nonlinear forced vibration response have been studied for the honeycomb sandwich panels. © 2010 Elsevier Ltd.


Luo W.-B.,Northeastern University China | Luo W.-B.,University of Wollongong | Chou S.-L.,University of Wollongong | Zhai Y.-C.,Northeastern University China | Liu H.-K.,University of Wollongong
Journal of Materials Chemistry A | Year: 2014

A graphene encapsulated LiFePO4 composite has been synthesized by self-assembly of surface modified LiFePO4 and graphene oxide with peptide bonds, followed by reduction. The graphene forms a continuous conductive coating network connecting the LiFePO4 nanoparticles to facilitate electron transportation, resulting in excellent high rate capability with 70% capacity retention at 50 C rate. The apparent activation energy of the graphene encapsulated LiFePO4 composite (9.6 kJ mol-1) is much lower than that of the carbon coated LiFePO4 (14.6 kJ mol -1). An excellent cycling performance is also demonstrated, in which the capacity loss is less than 8.6% after 950 cycles at 10 C. Therefore, this hybrid material is promising for use as a cathode material for high rate lithium ion batteries. This journal is © the Partner Organisations 2014.


Wang G.,Northeastern University China | Sun X.,Rensselaer Polytechnic Institute | Lu F.,Rensselaer Polytechnic Institute | Sun H.,Rensselaer Polytechnic Institute | And 4 more authors.
Small | Year: 2012

Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s -1, the specific capacitance of the pillared GP is 138 F g -1 and 83.2 F g -1 with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s -1, the specific capacitance can reach 80 F g -1 in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. The pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zheng B.-C.,Northeastern University China | Zheng B.-C.,Nanjing University of Information Science and Technology | Yang G.-H.,Northeastern University China
International Journal of Systems Science | Year: 2014

In this paper, based on sliding mode control approach, the robust stabilisation problem for a class of continuous-time Markovian jump linear uncertain systems with partly unknown transition rates is investigated. The transition rate matrix under consideration covers completely known, boundary known and completely unknown elements. By making use of linear matrix inequalities technique, sufficient conditions are presented to derive the linear switching surface and guarantee the stochastic stability of sliding mode dynamics. Then a sliding mode control law is designed to drive the state trajectory of the closed-loop system to the specified linear switching surface in finite time in spite of the existing uncertainties and unknown transition rates. Finally, an example is given to verify the validity of the theoretical results. © 2013 Taylor & Francis.


Lu L.,Shanghai JiaoTong University | Lu L.,TU Eindhoven | Lu L.,Northeastern University China | Lin Z.,University of Virginia
IEEE Transactions on Automatic Control | Year: 2011

This technical note revisits the problem of designing a static anti-windup gain for enlarging the domain of attraction of the resulting closed-loop system. By utilizing a composite quadratic Lyapunov function, which was originally proposed to study the stabilization problem for linear systems under actuator saturation, an existing LMI based design algorithm is enhanced to result in a nonlinear, possibly continuous, anti-windup gain. This nonlinear anti-windup gain enables us to obtain an estimate of the domain of attraction in the form of the convex hull of a group of ellipsoids, instead of a single ellipsoid that would result from a single Lyapunov function based design. Simulation results demonstrate the features of the proposed design the composite quadratic Lyapunov function brings about. © 2006 IEEE.


Zhao C.,Hong Kong University of Science and Technology | Gao F.,Hong Kong University of Science and Technology | Wang F.,Northeastern University China
AIChE Journal | Year: 2010

An improved independent component regression (M-ICR) algorithm is proposed by constructing joint latent variable (LV) based regressors, and a quantitative statistical analysis procedure is designed using a bootstrap technique for model validation and performance evaluation. First, the drawbacks of the conventional regression modeling algorithms are analyzed. Then the proposed M-ICR algorithm is formulated for regressor design. It constructs a dual-objective optimization criterion function, simultaneously incorporating quality-relevance and independence into the feature extraction procedure. This ties together the ideas of partial-least squares (PLS), and independent component regression (ICR) under the same mathematical umbrella. By adjusting the controllable suboptimization objective weights, it adds insight into the different roles of quality-relevant and independent characteristics in calibration modeling, and, thus, provides possibilities to combine the advantages of PLS and ICR. Furthermore, a quantitative statistical analysis procedure based on a bootstrapping technique is designed to identify the effects of LVs, determine a better model rank and overcome ill-conditioning caused by model over-parameterization. A confidence interval on quality prediction is also approximated. The performance of the proposed method is demonstrated using both numerical and real world data. © 2009 American Institute of Chemical Engineers.


Xu Y.,New Mexico State University | Liu W.,New Mexico State University | Gong J.,Northeastern University China
IEEE Transactions on Power Systems | Year: 2011

If generation in a power system is insufficient to power all loads, efficient load shedding operations may need to be deployed to maintain the supply-demand balance. This paper proposes a distributed multi-agent-based load shedding algorithm, which can make efficient load shedding decision based on discovered global information. During the information discovery process, only communications between immediate neighboring agents are used. The information discovery algorithm is represented as a discrete time linear system and the stability of which is analyzed according to average-consensus theorem. According to rigorous stability analysis, convergence of the designed algorithm can be guaranteed. To improve the speed of the algorithm, particle swarm optimization (PSO) is used to optimize the coefficients for information exchange so that the second largest eigenvalue of the iteration matrix is minimized. According to the designed algorithm, total net active power and operating status of loads can be discovered accurately even with faults. Based on the discovered information, coordinated load shedding decision can be made. © 2006 IEEE.


Ukwattage N.L.,Monash University | Ranjith P.G.,Monash University | Wang S.H.,Northeastern University China
Energy | Year: 2013

Mineral carbonation of alkaline waste materials is being studied extensively for its potential as a way of reducing the increased level of CO2 in the atmosphere. Carbonation converts CO2 into minerals which are stable over geological time scales. This process occurs naturally but slowly, and needs to be accelerated to offset the present rate of emissions from power plants and other emission sources. The present study attempts to identify the potential of coal fly ash as a source for carbon storage (sequestration) through ex-situ accelerated mineral carbonation. In the study, two operational parameters that could affect the reaction process were tested to investigate their effect on mineralization. Coal fly ash was mixed with water to different water-to-solid ratios and samples were carbonated in a pressure vessel at different initial CO2 pressures. Temperature was kept constant at 40 °C. According to the results, one ton of Hazelwood fly ash could sequester 7.66 kg of CO2. The pressure of CO2 inside the vessel has an effect on the rate of CO2 uptake and the water-to-solid ratio affects the weight gain after the carbonation of fly ash. The results confirm the possibility of the manipulation of process parameters in enhancing the carbonation reaction. © 2013 Elsevier Ltd.


Yi H.L.,Northeastern University China | Chen P.,Northeastern University China | Bhadeshia H.K.D.H.,Pohang University of Science and Technology
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2014

δ-TRIP is a low-alloy steel in which ferrite persists at all temperatures in the solid-state, with the remaining microstructure consisting of carbide-free bainite and carbon-enriched retained austenite. The present work explores for the first time, how changes in the intercritical annealing temperature and the transformation conditions associated with bainite influence the morphology and stability of the austenite, and hence the behavior of the microstructure during tensile deformation. It is found that the structure can be optimized to consist of a combination of blocky and film austenite that undergo transformation over a range of plastic strains, thus minimizing the possibility of plastic instabilities, and hence imparting considerable strength and uniform elongation. © 2014 The Minerals, Metals & Materials Society and ASM International.


Krivilyov M.,Udmurt State University | Volkmann T.,German Aerospace Center | Gao J.,Northeastern University China | Fransaer J.,Catholic University of Leuven
Acta Materialia | Year: 2012

Rapid solidification of stoichiometric Nd2Fe14B alloy in drop tube processing (DTP) is studied experimentally and theoretically. All relevant physical processes, including fluid flow, heat transfer, nucleation and crystal growth, are modeled at different scales. Transient nucleation is described using an extension of the classical nucleation model in terms of Poisson statistics and accounting for the geometrical factors of heterogeneous nuclei. Analysis of phase selection allows prediction of the appropriate processing conditions to optimize the magnetic properties of the as-solidified Nd-Fe-B samples by reducing the amount of α-Fe that forms during solidification. Comparison with experimental microstructural data confirms the modeling results. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Sun M.,Northeastern University China | Jia Y.,Beihang University
IET Control Theory and Applications | Year: 2010

In this study, a delay-dependent H∞ performance criterion that possess decoupling structure is derived for a class of time-delay systems. It is then extended to H∞ state-feedback synthesis for time-delay systems with polytopic uncertainty and multichannel H ∞ dynamic output-feedback synthesis for time-delay systems. All the conditions are given in terms of the linear matrix inequalities. In some previous descriptor methods, the products of controller matrices and Lyapunov matrices are completely separated in performance analysis, whereas it is not the case in controller synthesis. However, with the method in the paper, the weakness is eliminated. Numerical examples illustrate the effectiveness of our solutions as compared to results obtained by other methods. © 2010 The Institution of Engineering and Technology.


Long L.,Northeastern University China | Wang Z.,Hong Kong University of Science and Technology | Zhao J.,Northeastern University China
Automatica | Year: 2015

This paper investigates the problem of adaptive stabilization for a class of switched nonlinearly parameterized systems where the solvability of the adaptive stabilization problem for subsystems is unnecessary. A new switched adaptive control technique for the problem studied is set up by exploiting the generalized multiple Lyapunov functions method and the parameter separation technique. Different update laws are designed to reduce the conservativeness caused by adoption of a common update law for all subsystems. Also, the proposed technique permits removal of a common restriction in which the parameterization in the switched systems is restricted to a linear parameterization. As an application of the proposed design technique, stabilization for a class of non-triangular switched systems with nonlinear parameterization is achieved by design of adaptive controllers. Since no subsystem of such a switched system is assumed to be adaptively stabilizable, the problem under study cannot be handled by the existing methods. A two inverted pendulums as a practical example is also provided to demonstrate the effectiveness of the proposed design method. © 2015 Elsevier Ltd.


Wang X.,Northeastern University China | Cheng H.,University of Bedfordshire | Li K.,State University of New York at New Paltz | Li J.,University of Tsukuba | Sun J.,Northeastern University China
Journal of Parallel and Distributed Computing | Year: 2013

With the development of IP networks and intelligent optical switch networks, the backbone network tends to be a multi-granularity transport one. In a multi-granularity transport network (MTN), due to the rapid growth of various applications, the scale and complexity of network devices are significantly enhanced. Meanwhile, to deal with bursty IP traffic, the network devices need to provide continuous services along with excessive power consumption. It has attracted wide attention from both academic and industrial communities to build a power-efficient MTN. In this paper, we design an effective node structure for MTN. Considering the power savings on both IP and optical transport layers, we propose a mathematical model to achieve a cross-layer optimization objective for power-efficient MTN. Since this optimization problem is NP-hard (Hasan et al. (2010) [11]) and heuristic or intelligent optimization algorithms have been successfully applied to solve such kinds of problems in many engineering domains (Huang et al. (2011) [13], Li et al. (2011) [17] and Dong et al. (2011) [5]), a Green integrated Routing and Grooming algorithm based on Biogeography-Based Optimization (Simon (2008) [23]) (GRGBBO) is also presented. The simulation results demonstrate that, compared with the other BBO based and state-of-the-art power saving approaches, GRGBBO improves the power savings at a rate between 2%-15% whilst the high-level multi-user QoS (Quality of Services) satisfaction degree (MQSD) is guaranteed. GRGBBO is therefore an effective technique to build a power-efficient MTN. © 2013 Elsevier Inc. All rights reserved.


Yang H.,Ludong University | Zhang Z.,Nanjing Southeast University | Zhang S.,Northeastern University China
International Journal of Robust and Nonlinear Control | Year: 2011

In this paper, the consensus of second-order multi-agent dynamical systems with exogenous disturbances is studied. A pinning control strategy is designed for a part of agents of the multi-agent systems without disturbances, and this pinning control can bring multiple agents' states to reaching an expected consensus track. Under the influence of the disturbances, disturbance observers-based control (DOBC) is developed for disturbances generated by an exogenous system to estimate the disturbances. Asymptotical consensus of the multi-agent systems with disturbances under the composite controller can be achieved for fixed and switching topologies. Finally, by applying an example of multi-agent systems with switching topologies and exogenous disturbances, the consensus of multi-agent systems is reached under the DOBC with the designed parameters. Copyright © 2010 John Wiley & Sons, Ltd.


Yuan Y.,Northeastern University China | Wang G.,Microsoft | Wang H.,Hong Kong University of Science and Technology | Chen L.,Hubei Engineering University
Proceedings of the VLDB Endowment | Year: 2011

Retrieving graphs containing a query graph from a large graph database is a key task in many graph-based applications, includ-ing chemical compounds discovery, protein complex prediction, and structural pattern recognition. However, graph data handled by these applications is often noisy, incomplete, and inaccurate be-cause of the way the data is produced. In this paper, we study sub-graph queries over uncertain graphs. Specifically, we consider the problem of answering threshold-based probabilistic queries over a large uncertain graph database with the possible world seman-tics. We prove that problem is #P-complete, therefore, we adopt a filtering-and-verification strategy to speed up the search. In the filtering phase, we use a probabilistic inverted index, PIndex, based on subgraph features obtained by an optimal feature selection pro-cess. During the verification phase, we develop exact and bound algorithms to validate the remaining candidates. Extensive experi-mental results demonstrate the effectiveness of the proposed algo-rithms. © 2011 VLDB Endowment.


Yang M.,Nanjing Southeast University | Wu G.,Northeastern University China
Proceedings of the 20th International Conference Companion on World Wide Web, WWW 2011 | Year: 2011

The complexity and growing scale of RDF data has made data management back end the performance bottleneck of Semantic Web applications. Caching is one of the ways that could solve this problem. However, few existing research projects focus on caching in RDF data processing. We present an adaptive caching scheme that caches intermediate result of basic graph pattern SPARQL queries. Benchmark test results are provided to illustrate the effectiveness of our caching scheme. © 2011 Authors.


Heap M.J.,University of Strasbourg | Xu T.,Northeastern University China | Chen C.-F.,Northeastern University China
Bulletin of Volcanology | Year: 2014

Volcanic rocks and magma display a wide range of porosity and vesicle size, a result of their complex genesis. While the role of porosity is known to exert a fundamental control on strength in the brittle field, less is known as to the influence of vesicle size. To help resolve this issue, here, we lean on a combination of micromechanical (Sammis and Ashby's pore-emanating crack model) and stochastic (rock failure and process analysis code) modelling. The models show, for a homogenous vesicle size, that an increase in porosity (in the form of circular vesicles, from 0 to 40 %) and/or vesicle diameter (from 0.1 to 2.0 mm) results in a dramatic reduction in strength. For example, uniaxial compressive strength can be reduced by about a factor of 5 as porosity is increased from 0 to 40 %. The presence of vesicles locally amplifies the stress within the groundmass and promotes the nucleation of vesicle-emanating microcracks that grow in the direction of the applied macroscopic stress. As strain increases, these microcracks continue to grow and eventually coalesce leading to macroscopic failure. Vesicle clustering, which promotes the overlap and interaction of the tensile stress lobes at the north and south poles of neighbouring vesicles, and the increased ease of microcrack interaction, is encouraged at higher porosity and reduces sample strength. Once a microcrack nucleates at the vesicle wall, larger vesicles impart higher stress intensities at the crack tips, allowing microcracks to propagate at a lower applied macroscopic stress. Larger vesicles also permit a shorter route through the groundmass for the macroscopic shear fracture. This explains the reduction in strength at higher vesicle diameters (at a constant porosity). The modelling highlights that the reduction in strength as porosity or vesicle size increases is nonlinear; the largest reductions are observed at low porosity and small vesicle diameters. In detail, we find that vesicle diameter can play an important role in dictating strength at low porosity but is largely inconsequential above 15 % porosity. Vesicle clustering and stress lobe interaction are implicit at high porosity, regardless of the vesicle diameter. In the case of an inhomogeneous vesicle size, the microcracks grow from the largest vesicles, and brittle strength is closer to that of the largest vesicle end-member. The results of this study highlight the important role of vesicle size, and the complex interplay between porosity and vesicle size, in controlling the brittle strength of volcanic rocks and magma. © 2014 Springer-Verlag Berlin Heidelberg.


Yuan Y.,Northeastern University China | Wang G.,Northeastern University China | Chen L.,Hong Kong University of Science and Technology | Wang H.,Microsoft
IEEE Transactions on Knowledge and Data Engineering | Year: 2013

As a popular search mechanism, keyword search has been applied to retrieve useful data in documents, texts, graphs, and even relational databases. However, so far, there is no work on keyword search over uncertain graph data even though the uncertain graphs have been widely used in many real applications, such as modeling road networks, influential detection in social networks, and data analysis on PPI networks. Therefore, in this paper, we study the problem of top-k keyword search over uncertain graph data. Following the similar answer definition for keyword search over deterministic graphs, we consider a subtree in the uncertain graph as an answer to a keyword query if 1) it contains all the keywords; 2) it has a high score (defined by users or applications) based on keyword matching; and 3) it has low uncertainty. Keyword search over deterministic graphs is already a hard problem as stated in [1], [2], [3]. Due to the existence of uncertainty, keyword search over uncertain graphs is much harder. Therefore, to improve the search efficiency, we employ a filtering-and-verification strategy based on a probabilistic keyword index, PKIndex. For each keyword, we offline compute path-based top-k probabilities, and attach these values to PKIndex in an optimal, compressed way. In the filtering phase, we perform existence, path-based and tree-based probabilistic pruning phases, which filter out most false subtrees. In the verification, we propose a sampling algorithm to verify the candidates. Extensive experimental results demonstrate the effectiveness of the proposed algorithms. © 1989-2012 IEEE.


Tang L.,Northeastern University China | Guan J.,Civil Aviation University of China | Hu G.,Baosteel
Computers and Industrial Engineering | Year: 2010

This article explores the coordinated scheduling problem between production and transportation in a steelmaking shop. Two models arising from steelmaking and refining operations are considered. The first model assumes that there is a converter at the steelmaking operation and a refining furnace at the refining operation. A transporter with capacity one is available to carry out jobs from converter to a refining furnace. The objective is to minimize the maximum completion time. For this model, we provide an algorithm with worst case ratio of two and show the computational results. The second model considers more practical situation in which jobs are processed in identical parallel converters first, and then the jobs coming from same converter are transported by a dedicated trolley with capacity one to the next operations. Two objectives are considered in the second model. One is to minimize the sum of maximum completion time, idle time penalties and waiting time penalties satisfying waiting time constraints. The other is to minimize the sum of maximum completion time, idle times penalties and hot consumption penalties related to waiting times while satisfying waiting time constraints. For the model, we develop a tabu search algorithm, provide the computational results and then give the worst case analysis. © 2009 Elsevier Ltd. All rights reserved.


Zhao C.,Hong Kong University of Science and Technology | Gao F.,Hong Kong University of Science and Technology | Wang F.,Northeastern University China
Industrial and Engineering Chemistry Research | Year: 2010

Spectroscopy is a useful tool for analyzing chemical information in batch processes. However, conventional spectroscopic techniques can lead to complex model structures and difficult-to-interpret results because of the direct use of redundant wavelength variables. To solve this problem, the ICA technique has been used first to reveal the underlying independent sources from the observed mixtures and their mixing coefficients. This analysis associates the constituent species with their respective effects on the mixture spectra, which could make more sense for spectroscopy. In the following article, the use of mixing coefficients instead of redundant wavelength variables can provide a convenient modeling platform from which the phase-specific characteristics of chemical reactions are readily identified. Consequently, a phase-based joint modeling framework is formulated for process monitoring by combining different latent-variable- (LV-) based algorithms. It decomposes different types of systematic variations in spectral measurements (X) and then sets up different monitoring systems for them. Monitoring different parts of X can provide abundant process information about the status of the operation from a comprehensive viewpoint, thus benefitting process understanding and fault detection. The effectiveness of this approach is demonstrated by application to two case studies. © 2010 American Chemical Society.


Liu F.,Northeastern University China | Wang J.,Northeastern University China | Sun C.,Nanjing Southeast University | Du R.,Northeastern University China
IEEE Transactions on Antennas and Propagation | Year: 2012

Direction-of-arrival (DOA) estimation is an important problem in array signal processing. An effective spatial differencing method is addressed, for the DOA estimation problem of a number of uncorrelated and coherent narrowband signals simultaneously impinging on the far field of a uniform linear array (ULA). In the proposed method, the uncorrelated sources are firstly estimated using conventional subspace methods, and then they are eliminated by exploiting the spatial differencing technique, that is, only coherent components remain in the spatial differencing matrix. Finally, the remaining coherent signals are estimated by utilizing the spatial differencing matrix. Compared with the previous works, the presented method can improve the DOA estimation accuracy, as well as increase the maximal number of detectable signals. The theoretical analysis and simulation results confirm the effectiveness of the method. © 2012 IEEE.


Guan R.G.,Northeastern University China | Je Y.T.,Pohang University of Science and Technology | Zhao Z.Y.,Northeastern University China | Lee C.S.,Pohang University of Science and Technology
Materials and Design | Year: 2012

In order to obtain a more quantitative understanding of the formability of Ti-6Al-4V alloys related to different initial microstructures, hot compression tests were conducted on alloys with three different initial microstructures, and Ti-6Al-4V alloy forging process for production of gear reverse idle was also studied. Three different microstructures were first established by combinations of several heat treatments for the first time. Average cooling rate obviously affects α lamellar spacing but does not strongly affect colony size. Measured flow curves for Ti-6Al-4V alloy exhibited peak flow stresses at relative low strains followed flow softening. For a given temperature and strain rate microstructures with finer lamellar spacing exhibited higher flow stresses. Flow curves for different colony sizes were almost coincident. It is concluded that α lamellar spacing strongly affects flow stress but the effect of colony size on flow stress is weak. Deformation resistances for different microstructures were predicted under various deformation conditions using hyperbolic sine law. The predicted constitutive functions coincided well with the results of hot compression tests. Dynamic recovery, dynamic recrystallization and breakage of lamellar structures result in finer microstructures and flow softening during hot forging processing. Cracks were likely to form with coarser lamellar spacing samples at lower forging temperatures. © 2011 Elsevier Ltd.


Zhang J.,Northeastern University China | Di H.,Northeastern University China | Wang X.,Northeastern University China | Cao Y.,Northeastern University China | Ma T.,Baosteel
Materials and Design | Year: 2013

In this study, constitutive analysis has been carried out on Fe-23Mn-2Al-0.2C twinning induced plasticity (TWIP) steel. For this purpose, hot compression tests were conducted on a Gleeble-3500 thermo-mechanical simulator in the temperature range of 900-1150°C and the strain rate range of 0.001-20 S-1. The effects of deformation heating and friction on flow stress were analyzed and corrected. On the basis of Sellars-Tegart-Garofalo equation, the strain-dependent constitutive equations of the steel were derived. The results show that deformation heating has a significant influence on the flow stress at lower temperatures and higher strain rates, while the frictional effect is slight even at the highest strain level investigated. Comparison of the calculated flow stress with the experimental data suggests that the developed constitutive equations can adequately describe the relationships between the flow stress, strain rate, temperature and strain of the steel during hot deformation. This is supported by a high correlation coefficient (R = 0.996) and a low average absolute relative error (AARE = 3.31%) for the entire deformation condition range investigated. © 2012 Elsevier Ltd.


Yuan Y.,Northeastern University China | Wang G.,Northeastern University China | Chen L.,Hong Kong University of Science and Technology | Wang H.,Microsoft
Proceedings of the VLDB Endowment | Year: 2012

Many studies have been conducted on seeking the efficient solution for subgraph similarity search over certain (deterministic) graphs due to its wide application in many fields, including bioinformatics, social network analysis, and Resource Description Framework (RDF) data management. All these works assume that the underlying data are certain. However, in reality, graphs are often noisy and uncertain due to various factors, such as errors in data extraction, inconsistencies in data integration, and privacy preserving purposes. Therefore, in this paper, we study subgraph similarity search on large probabilistic graph databases. Different from previous works assuming that edges in an uncertain graph are independent of each other, we study the uncertain graphs where edges' occurrences are correlated. We formally prove that subgraph similarity search over probabilistic graphs is #P-complete, thus, we employ a filter-and-verify framework to speed up the search. In the filtering phase, we develop tight lower and upper bounds of sub-graph similarity probability based on a probabilistic matrix index, PMI. PMI is composed of discriminative subgraph features associated with tight lower and upper bounds of subgraph isomorphism probability. Based on PMI, we can sort out a large number of probabilistic graphs and maximize the pruning capability. During the verification phase, we develop an efficient sampling algorithm to validate the remaining candidates. The efficiency of our proposed solutions has been verified through extensive experiments. © 2012 VLDB Endowment.


Tong Y.,Hong Kong University of Science and Technology | Chen L.,Hong Kong University of Science and Technology | Cheng Y.,Northeastern University China | Yu P.S.,University of Illinois at Chicago
Proceedings of the VLDB Endowment | Year: 2012

In recent years, due to the wide applications of uncertain data, mining frequent itemsets over uncertain databases has attracted much attention. In uncertain databases, the support of an itemset is a random variable instead of a fixed occurrence counting of this itemset. Thus, unlike the corresponding problem in deterministic databases where the frequent itemset has a unique definition, the frequent itemset under uncertain environments has two different definitions so far. The first definition, referred as the expected support-based frequent itemset, employs the expectation of the support of an itemset to measure whether this itemset is frequent. The second definition, referred as the probabilistic frequent itemset, uses the probability of the support of an itemset to measure its frequency. Thus, existing work on mining frequent itemsets over uncertain databases is divided into two different groups and no study is conducted to comprehensively compare the two different definitions. In addition, since no uniform experimental platform exists, current solutions for the same definition even generate inconsistent results. In this paper, we firstly aim to clarify the relationship between the two different definitions. Through extensive experiments, we verify that the two definitions have a tight connection and can be unified together when the size of data is large enough. Secondly, we provide baseline implementations of eight existing representative algorithms and test their performances with uniform measures fairly. Finally, according to the fair tests over many different benchmark data sets, we clarify several existing inconsistent conclusions and discuss some new findings. © 2012 VLDB Endowment.


Wang G.,Northeastern University China | Xin J.,Northeastern University China | Chen L.,Hong Kong University of Science and Technology | Liu Y.,Hong Kong University of Science and Technology
IEEE Transactions on Knowledge and Data Engineering | Year: 2012

Reverse skyline query plays an important role in many sensing applications, such as environmental monitoring, habitat monitoring, and battlefield monitoring. Due to the limited power supplies of wireless sensor nodes, the existing centralized approaches, which do not consider energy efficiency, cannot be directly applied to the distributed sensor environment. In this paper, we investigate how to process reverse skyline queries energy efficiently in wireless sensor networks. Initially, we theoretically analyzed the properties of reverse skyline query and proposed a skyband-based approach to tackle the problem of reverse skyline query answering over wireless sensor networks. Then, an energy-efficient approach is proposed to minimize the communication cost among sensor nodes of evaluating range reverse skyline query. Moreover, optimization mechanisms to improve the performance of multiple reverse skylines are also discussed. Extensive experiments on both real-world data and synthetic data have demonstrated the efficiency and effectiveness of our proposed approaches with various experimental settings. © 2012 IEEE.


Feng G.-L.,CAS Wuhan Institute of Rock and Soil Mechanics | Feng X.-T.,CAS Wuhan Institute of Rock and Soil Mechanics | Chen B.-R.,CAS Wuhan Institute of Rock and Soil Mechanics | Xiao Y.-X.,CAS Wuhan Institute of Rock and Soil Mechanics | Yu Y.,Northeastern University China
Rock Mechanics and Rock Engineering | Year: 2015

Early warning of rockbursts remains a worldwide challenge in rock engineering. In this work, a microseismicity-based method of rockburst warning in tunnels is proposed to warn of and reduce the risk of rockburst. The method uses real-time microseismic data and an established rockburst warning formula to provide dynamic warning of rockburst risk during excavation of a tunnel. The establishment of the rockburst warning formula involves several key parts. These include a rockburst database, selection of typical rockburst cases, functional relationships between microseismicity and rockbursts, optimal weighting coefficients, and dynamic updating. By using the proposed method, the probability of strain and strain-structure slip rockbursts of different intensity (extremely intense, intense, moderate, slight, and none) can be warned of in real time. The method has been successfully applied to rockburst warning in deeply buried tunnels at the Jinping II hydropower project (about 11.6 km in total for D & B tunnels). This success illustrates the applicability of the proposed method. In addition, it is found that during the rockburst development process, the microseismic eigenvalues for strainbursts are bigger than in strain-structure slip rockbursts of the same intensity. © 2014, Springer-Verlag Wien.


Hua J.,Northeastern University China | Zhang Y.,Baosteel | Wu C.,Baosteel
Journal of Materials Processing Technology | Year: 2011

The combined pulsed magnetic field (C-PMF) obtained by simultaneously imposing pulsed and static magnetic field during solidification has been proposed to refine the solidification structure. Compared to the imposition of a single pulsed magnetic field, a more refined structure can be observed under C-PMF. The key factors to affect grain refinement under C-PMF consisted of the vibration frequency characterized by the static magnetic field, pulsed discharge voltage, and the vibration frequency characterized by the pulsed discharge frequency. The microstructure revealed that the grain size decreased with the increasing static magnetic field. The pulsed discharge voltage had an optimum value for obtaining fine grains. Furthermore, when the pulsed discharge frequency was equal to the intrinsic frequency of the liquid metal in a filled cylindrical vessel, resonance vibration occurred in the liquid surface, and grain refinement was promoted. © 2010 Elsevier B.V. All rights reserved.


Grant
Agency: Department of Defense | Branch: Missile Defense Agency | Program: STTR | Phase: Phase I | Award Amount: 149.84K | Year: 2011

Active defects negatively impact the performance of IRFPAs by increasing noise at various levels up to, and including, catastrophic degradation. Evidence indicates that"killer defects"are related to the interaction of open core screw dislocations with impurities that remain after substrate preparation, prior to HgCdTe growth. This impurity diffusion creates a conducting channel that shorts the junction. The effectiveness of atomic hydrogen for low-temperature cleaning, overlayer removal and stoichiometry recovery for etched semiconductor surfaces has been demonstrated. We will extend this to CdZnTe and Ge substrates and demonstrate cleaning of HgCdTe after process etch steps. Additionally ARI has demonstrated a method for introducing hydrogen into the FPA epilayer during processing. The hydrogen migrates into the HgCdTe and attaches to dislocations and yield-limiting defects, effectively passivating the defect with improvement in both operability and yield. We will use ARI"s process to develop a practical method introducing hydrogen cleaning into HgCdTe processing to produce clean, stoichiometric surfaces prior to growth and passivation while providing hydrogen passivation to mitigate the effect of remaining defects. This will achieve the overall objective of significantly improving operability by reducing defects and dislocations in large format infrared detector materials while also hydrogenating to improve operability.


Grant
Agency: Department of Defense | Branch: Missile Defense Agency | Program: STTR | Phase: Phase II | Award Amount: 1000.00K | Year: 2012

In Phase I we demonstrated a novel in-situ cleaning technique based on UV-activated surface reactions involving ozone and hydrogen to remove organic adsorbates and chemically-bonded impurities, e.g oxides, from the substrate surface. In Phase II the program will develop this process to significantly decrease the density of material defects in large-format, infrared, focal-plane arrays. Electrically-active defects impact array performance by increasing noise levels up to catastrophic degradation. The focus of this project is the elimination of active defects formed during molecular-beam epitaxy (MBE) of HgCdTe (the active layer in the arrays) on alternative substrates, i.e. materials other than lattice-matched CdZnTe. A significant fraction of as-grown defects nucleate at surface sites related to impurities or artifacts associated with ineffectual substrate cleaning prior to MBE growth. This will be demonstrated on alternative substrates, including InSb, GaAs, Ge and Si wafers using advanced surface characterization techniques, as well as through evaluation of HgCdTe epilayers grown on buffered InSb and GaAs. In addition, HgCdTe-based devices fabricated using photolytically cleaned substrates will be compared to ones fabricated using standard cleaning techniques to demonstrate this process. This will achieve the overall objective of significantly improving operability by reducing defects and dislocations in large-format infrared detector materials.


Grant
Agency: Department of Health and Human Services | Branch: National Institutes of Health | Program: STTR | Phase: Phase I | Award Amount: 224.99K | Year: 2015

DESCRIPTION provided by applicant Clinical treatment of infants in the neonatal intensive care unit NICU is particularly challenging due to their small anatomies medical instability and immature physiological processes Treatment is often complicated by the lack of therapeutic devices and instrumentation designed specifically to accommodate this unique patient population For instance current vascular access catheters are not specifically designed and customized for the very small vasculature of neonatal patients which exacerbates common complications including vessel perforation thrombotic occlusions catheter breakage and infection Creating sophisticated patient specific neonatal catheters would dramatically reduce these complications and work to better serve this population D printing offers the ability to generate complex and patient specific D architectures Our collaborators at Northeastern University are pioneering D Magnetic Printing a new technique in which reinforcing ceramic fibers are aligned with magnetic fields during the printing process to create composites with highly tunable reinforcement architectures We will use D Magnetic Printing to produce strong flexible patient specific neonatal vascular access catheters Specifically we will generate customizable composite catheter tubing with enhanced wall stiffness and strength while maintaining flexibility burst strength and kink resistance Such a novel design approach will allow production of next generation neonatal vascular access catheters with thinner walls permitting reduction of catheter diameters and or higher fluid transport rates D Magnetic Printing of neonatal catheters offers the advantages of improved resistance to catheter sidewall collapse and kinking that often leads to catheter occlusion and higher fluid transport rates which will minimize the probability of thrombus and fibrin sheath formation Furthermore the D printing technique is compatible with conventional catheter materials such as polyurethane and silicone and allows utilization of biocompatible fibers like hydroxyapatite facilitating regulatory approval pathways The printing method is robust low cost and scalable In Phase I we will print a variety of catheter tubing with customized fiber architectures including longitudinal lateral and radial reinforcement using both polyurethane and silicone Sample characterization will be used to fine tune a finite element analysis model of the material This model will be used to design improved tubing for comparison to conventionally extruded tubing Our primary objective is to demonstrate the production of tubing with reduced wall thickness optimized mechanical properties and enhanced flow characteristics In Phase II this model will be used to design functional catheters having complex reinforcement architecture PUBLIC HEALTH RELEVANCE In this program a novel Magnetic D Printing technique will be developed for printing pediatric catheters This technique will enable highly customized immediate printing of devices for a population that often has unique and underserved requirements The technique introduces a novel means of controlling the alignment of reinforcing fibers which will give the designer a powerful tool to improve critical catheter characteristics such as wall thickness flow rate and kink resistance which are especially important in the small sizes required by pediatric patients These improvements will ultimately improve performance and reduce catheter related complications


Yang C.,Northeastern University China | Gao J.,Northeastern University China | Zhang Y.K.,Northeastern University China | Kolbe M.,German Aerospace Center | Herlach D.M.,German Aerospace Center
Acta Materialia | Year: 2011

Rapid solidification processes of glass-fluxed Ni81.3Sn 18.7 eutectic alloys at various undercoolings were observed in situ using a high-speed camera. The microstructure of the samples was characterized using optical microscopy, scanning electron microscopy and electron back-scattering diffraction analysis. It was found that the recalescence front sweeps the sample surface from one side to the other, which coincides with the formation of a directional solidification microstructure. Such a finding suggests that it is feasible to measure crystal growth velocities in the undercooled liquid by tracking the loci of the recalescence front. The measured data show sudden acceleration of crystal growth kinetics at a medium undercooling, giving evidence for a transition from coupled growth to uncoupled growth. Microscopic studies revealed that the sample with an undercooling of 202 K comprises two types of anomalous eutectic, which are distinguished by the size and orientations of Ni-rich grains. The results verify a recent hypothesis that anomalous eutectic in undercooled Ni-Sn alloys has a dual origin: it results from eutectic dendrites growing at low undercoolings and from single-phase Ni-rich dendrites growing at high undercoolings. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Chang X.-H.,Bohai University | Chang X.-H.,Northeastern University China | Yang G.-H.,Northeastern University China
Information Sciences | Year: 2010

This paper deals with the stabilization of continuous-time Takagi-Sugeno (T-S) fuzzy control systems. Based on fuzzy Lyapunov functions and nonparallel distributed compensation (non-PDC) control laws, new stabilization conditions are represented in the form of linear matrix inequalities (LMIs). The theoretical proof shows that the proposed conditions can provide less conservatism than the existing results in the literature. Moreover, in order to demonstrate the effectiveness of the non-PDC control laws, the problem of H∞ controller design for T-S fuzzy systems is also studied. Simulation examples are given to illustrate the merits of the proposed methods. © 2010 Elsevier Inc. All rights reserved.


Wang X.,Northeastern University China | Cheng H.,University of Bedfordshire | Huang M.,Northeastern University China
Engineering Applications of Artificial Intelligence | Year: 2013

The technical development drives the future networks to become large-scale, heterogeneous, and dynamic. Bio-inspired networking can help reduce the time-space complexity of the complex network. Due to the good features such as self-organization and self-management, self-organizing network (SON) will most probably be a priority choice for the next generation network. In this paper, a swarm intelligence based Quality of Service (QoS) routing protocol is proposed for SON. The inaccurate routing and QoS information is described with fuzzy mathematics whilst the utilities of both the user and the network service provider are considered by applying game theory. Based on the multi-robot navigation algorithm, the protocol is able to search a routing path which can satisfy the user QoS requirements and achieve the Pareto optimal utilities of the user and the network service provider under Nash equilibrium. The proposed protocol is implemented and evaluated by extensive simulation experiments. The results show that it beats both other swarm intelligence based routing protocols and the traditional Dijkstra algorithm based routing protocol. The searched routing paths support the win-win effect for both the user and the network service provider. © 2012 Elsevier Ltd. All rights reserved.


Chu M.,Northeastern University China | Yagi J.-I.,Tohoku University
Steel Research International | Year: 2010

The new process of top gas recycling by hot reducing gas (HRG) injection has been developed in this study in order to overcome the disadvantageous problems under the lower temperature operation, to enhance the utilization of top gas carbon and to reduce carbon dioxide emission of blast furnaces. Numerical evaluation of blast furnace top gas recirculation together with lower-temperature operation was performed by means of a multi-fluid blast furnace model. The simulation results show that, (1) under the lower temperature operation, the shaft injection, or simultaneous shaft and tuyere injection of hot reducing gas is effective to increase the heat supply and to enrich the reduction atmosphere in the shaft zone, to improve the reduction of iron burdens, and enhance the efficiency of the shaft zone. (2) If top gas is recirculated by HRG on the basis of lower temperature operation, a highly efficient low-carbon blast furnace is obtained. The productivity of the furnace shows a remarkable increase and the total reducing agent rate shows a considerable decrease. Furthermore, the top gas carbon utilization is enhanced and the carbon dioxide emission rate is lowered. (3) Generally, shaft efficiency, carbon emission and heat efficiency under simultaneous tuyere and shaft injection are comparatively better than in the other two methods of single injection. Copyright © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu H.,Northeastern University China | Xu Q.,Northeastern University China | Yan C.,CAS Shenyang Institute of Metal Research | Qiao Y.,Northeastern University China
Electrochimica Acta | Year: 2011

The graphite plate is easily suffered from corosion because of CO 2 evolution when it acts as the positive electrode for vanadium redox flow battery. The aim is to obtain the initial potential for gas evolution on a positive graphite electrode in 2 mol dm -3 H 2SO 4 + 2 mol dm -3 VOSO 4 solution. The effects of polarization potential, operating temperature and polarization time on extent of graphite corrosion are investigated by potentiodynamic and potentiostatic techniques. The surface characteristics of graphite electrode before and after corrosion are examined by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The results show that the gas begins to evolve on the graphite electrode when the anodic polarization potential is higher than 1.60 V vs saturated calomel electrode at 20 °C. The CO 2 evolution on the graphite electrode can lead to intergranular corrosion of the graphite when the polarization potential reaches 1.75 V. In addition, the functional groups of COOH and CO introduced on the surface of graphite electrode during corrosion can catalyze the formation of CO 2, therefore, accelerates the corrosion rate of graphite electrode. © 2011 Elsevier Ltd.


Wang M.,Northeastern University China | Wang M.,CAS Shenyang Institute of Metal Research | Abbineni G.,University of Oklahoma | Clevenger A.,University of Oklahoma | And 2 more authors.
Nanomedicine: Nanotechnology, Biology, and Medicine | Year: 2011

New generation fluorophores, also termed upconversion nanoparticles (UCNPs), have the ability to convert near infrared radiations with lower energy into visible radiations with higher energy via a nonlinear optical process. Recently, these UCNPs have evolved as alternative fluorescent labels to traditional fluorophores, showing great potential for imaging and biodetection assays in both in vitro and in vivo applications. UCNPs exhibit unique luminescent properties, including high penetration depth into tissues, low background signals, large Stokes shifts, sharp emission bands, and high resistance to photobleaching, making UCNPs an attractive alternative source for overcoming current limitations in traditional fluorescent probes. In this article, we discuss the recent progress in the synthesis and surface modification of rare-earth doped UCNPs with a specific focus on their biological applications. From the Clinical Editor: Upconversion nanoparticles - a new generation of fluorophores - convert near infrared radiations into visible radiations via a nonlinear optical process. These UCNPs have evolved as alternative fluorescent labels with great potential for imaging and biodetection assays in both in vitro and in vivo applications. © 2011 Elsevier Inc.


Qian Y.H.,CAS Shenyang Institute of Metal Research | Niu D.,Northeastern University China | Xu J.J.,CAS Shenyang Institute of Metal Research | Li M.S.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

To investigate the influence of chromium content on corrosion characteristics of weathering steels, the electrochemical measurements were performed on the steels containing 0-9% Cr (wt.%) in NaHSO3 aqueous solution. The results indicated that the open circuit potential of these steels shifted to the positive direction remarkably, because the additions of Cr improved the passivation capability of the steels. The corrosion current density of the steels containing more than 7% Cr (wt.%) decreased significantly after pre-rusted treatment, implying the corrosion resistance could be enhanced by the formation of protective goethite rust layer. © 2013 Elsevier Ltd.


Liu H.S.,CAS Shenyang Institute of Metal Research | Zhang B.,Northeastern University China | Zhang G.P.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

Here we reveal that a Cu/Cu laminated composite with an appropriate mechanical contrast between constituent layers can effectively improve the toughness and fatigue strength of cold rolled Cu. The local interface delamination-induced retardation of cracking and the secondary initiation of fatigue cracks at inner layer surfaces are the main mechanisms. Such the single material laminated with mechanical contrast provides a potential way to improve fatigue strength. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Liu H.S.,CAS Shenyang Institute of Metal Research | Zhang B.,Northeastern University China | Zhang G.P.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

A cold-rolled metal sheet is usually of high strength but low plasticity due to the onset of premature local necking. Here, we reveal that the tensile plasticity of cold-rolled Cu can be effectively enhanced by a layered structure stacked alternately by thicker Cu and thinner Al layers. The layer interface in the composite strongly constrains and delays the development of premature local necking of the cold-rolled Cu layer. A potential way to improve plasticity without losing strength is suggested. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Hao L.,CAS Shenyang Institute of Metal Research | Zhang S.,Northeastern University China | Zhang S.,Laiwu Steel Group | Dong J.,CAS Shenyang Institute of Metal Research | Ke W.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2012

The evolution of atmospheric corrosion of MnCuP weathering steel in a simulated coastal-industrial atmosphere was investigated by weight gain, SEM, XRD, and electrochemical measurements. The results indicate that the corrosion kinetics divides into two stages with a higher corrosion rate in the first stage and a lower rate in the second stage. The increased amount of α-FeOOH indicates an improved resistance of the rust. The rust enhances initially and then stabilizes the cathodic process, but the anodic process tends to be inhibited. The EIS results indicate that the protective ability of the rust layer can be evaluated by the charge transfer resistance. © 2012.


Liu S.,Northeastern University China | Su X.,Jilin University
RSC Advances | Year: 2014

As a novel nanomaterial, I-III-VI type quantum dots have been a major focus of research and development in the past decade, which can be attributed to their tunable fluorescence emission wavelengths, high photostability and low toxicity of chemical composition. In addition, I-III-VI type quantum dots have fluorescence emission wavelengths in the near-infrared regions, and thus have potential applications in bioimaging. In this review, several recent advances regarding I-III-VI type quantum dots are summarized, including synthetic methods, characteristics and some applications. Furthermore, we discuss the prospects and challenges related to this novel type of quantum dots. This journal is © the Partner Organisations 2014.


Sun H.,Tsinghua University | Liu Y.,Northeastern University China | Yu Y.,Northeast Petroleum University | Ahmad M.,Pakistan Institute of Nuclear Science and Technology | And 2 more authors.
Electrochimica Acta | Year: 2014

Mesoporous Co3O4 nanosheets-3D graphene networks (3DGN) hybrid materials have been synthesized by combining chemical vapor deposition (CVD) and hydrothermal method and investigated as anode materials for Li-ion batteries (LIBs). Microscopic characterizations have been performed to confirm the 3DGN and mesoporous Co3O4 nanostructures. The specific surface area and pore size of the hybrid structures have been found ∼ 34.5 m2g-1 and ∼ 3.8 nm respectively. It has been found that the Co3O4/3DGNs composite displays better LIB performance with enhanced reversible capacity, good cyclic performance and rate capability as compare with Co3O4/CNT and Co 3O4 structures. Electrochemical impedance spectroscopy (EIS) results show that the addition of 3DGN not only preserves high conductivity of the composite electrode, but also largely enhanced the electrochemical activity of Co3O4 during the cycling processes. The improved electrochemical performance is considered due to the addition of 3DGNs which prevent the cracking of electrode. In addition, the large specific surface area and porous nature of the Co3O4 nanosheets are also very convenient and accessible for electrolyte diffusion and intercalation of Li+ ions into the active phases. Therefore, this combination can be considered to be an attractive candidate as an anode material for LIBs. © 2013 Elsevier Ltd.


Zhang Y.,Northeastern University China | Yang B.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2014

The magnetic properties and magnetocaloric effect (MCE) in ErNi 2-xFexB2C have been studied. Substitution of Fe for Ni lowered the magnetic transition temperature T M, and reduced the magnetic hysteresis of ErNi2B 2C. An inverse MCE was observed under low magnetic field and at low temperatures, which is attributed to the nature of antiferromagnetic state for the present ErNi2-xFexB2C compounds. A normal MCE was observed under higher magnetic field changes, which is related to a field-induced first order metamagnetic transition from antiferromagnetic to ferromagnetic state. The maximum values of magnetic entropy change -ΔSMmax are 14.5, 12.7, and 10.6 J/kg K with a magnetic field change of 0-70 kOe for x = 0, 0.1, and 0.2 in ErNi 2-xFexB2C, respectively. © 2014 Elsevier B.V. All rights reserved.


Chang X.-H.,Bohai University | Chang X.-H.,Northeastern University China | Yang G.-H.,Northeastern University China
IEEE Transactions on Signal Processing | Year: 2011

This paper is concerned with the problem of nonfragile H∞ filtering for a class of continuous-time fuzzy systems. Attention is focused on the design of a filter such that the filtering error system preserves a prescribed H∞ performance, where the filter to be designed is assumed to have gain variations. By using the quadratic Lyapunov function approach and adding slack matrix variables, sufficient conditions for designing the nonfragile H∞ filter are proposed in terms of solutions to a set of linear matrix inequalities (LMIs). Finally, a simulation example will be given to show the efficiency of the proposed design methods. © 2010 IEEE.


Chen H.,Harbin Institute of Technology | Zhang E.,Northeastern University China | Yang K.,CAS Shenyang Institute of Metal Research
Materials Science and Engineering C | Year: 2014

In order to improve the biocompatibility and the corrosion resistance in the initial stage of implantation, a phosphate (CaZn2(PO 4)2 · 2H2O) coating was obtained on the surface of pure iron by a chemical reaction method. The anti-corrosion property, the blood compatibility and the cell toxicity of the coated pure iron specimens were investigated. The coating was composed of some fine phosphate crystals and the surface of coating was flat and dense enough. The electrochemical data indicated that the corrosion resistance of the coated pure iron was improved with the increase of phosphating time. When the specimen was phosphated for 30 min, the corrosion resistance (Rp) increased to 8006 Ω. Compared with that of the naked pure iron, the anti-hemolysis property and cell compatibility of the coated specimen was improved significantly, while the anti-coagulant property became slightly worse due to the existence of element calcium. It was thought that phosphating treatment might be an effective method to improve the biocompatibility of pure iron for biomedical application. © 2013 Elsevier B.V.


Watanabe T.,Northeastern University China | Watanabe T.,Tohoku University
Journal of Materials Science | Year: 2011

A brief introduction of the historical background of grain boundary engineering for structural and functional polycrystalline materials is presented herewith. It has been emphasized that the accumulation of fundamental knowledge about the structure and properties of grain boundaries and interfaces has been extensively done by many researchers during the past one century. A new approach in terms of the concept of grain boundary and interface engineering is discussed for the design and development of high performance materials with desirable bulk properties. Recent advancements based on these concepts clearly demonstrate the high potential and general applicability of grain boundary engineering for various kinds of structural and functional materials. Future prospects of the grain boundary and interface engineering have been outlined, hoping that a new dimension will emerge pertaining to the discovery of new materials and the generation of a new property originating from the presence of grain boundaries and interfaces in advanced polycrystalline materials. © 2011 Springer Science+Business Media, LLC.


Liu G.-Y.,Jilin University | Wang H.-Y.,Jilin University | Liu G.-Q.,Northeastern University China | Yang Z.-Z.,Jilin University | And 2 more authors.
Electrochimica Acta | Year: 2013

Dual-phase Li4Ti5O12-TiO2 nanocrystallines are prepared by a hydrothermal process and subsequent heat treatment. The as-prepared Li4Ti5O12-TiO 2 nanocrystallines measure around 15-25 nm in size and have abundant phase interfaces. Electrochemical measurements demonstrate that dual-phase Li4Ti5O12-TiO2 exhibit good electrochemical performance over individual single-phase Li4Ti 5O12, especially at high current rates. Initial discharge capacities of dual-phase Li4Ti5O12-TiO 2 nanocrystallines are 241 and 202 mAh g-1 at discharge rates of 0.2 and 5 C, respectively. Even after 50 cycles at 20 C, the capacity still remains 140 mAh g-1, which is four times greater than that of single-phase Li4Ti5O12 (29 mAh g-1). The high electrochemical performance indicates that dual-phase Li 4Ti5O12-TiO2 nanocrystallines are highly promising anode materials for lithium ion battery applications. © 2012 Elsevier Ltd.


Wu J.,Tsinghua University | Yan S.,Tsinghua University | Xie L.,Northeastern University China
Acta Astronautica | Year: 2011

To address the impact of solar array anomalies, it is important to perform analysis of the solar array reliability. This paper establishes the fault tree analysis (FTA) and fuzzy reasoning Petri net (FRPN) models of a solar array mechanical system and analyzes reliability to find mechanisms of the solar array fault. The index final truth degree (FTD) and cosine matching function (CMF) are employed to resolve the issue of how to evaluate the importance and influence of different faults. So an improvement reliability analysis method is developed by means of the sorting of FTD and CMF. An example is analyzed using the proposed method. The analysis results show that harsh thermal environment and impact caused by particles in space are the most vital causes of the solar array fault. Furthermore, other fault modes and the corresponding improvement methods are discussed. The results reported in this paper could be useful for the spacecraft designers, particularly, in the process of redesigning the solar array and scheduling its reliability growth plan. © 2011 Elsevier Ltd. All rights reserved.


Niu B.,Northeastern University China | Niu B.,Bohai University | Zhao J.,Northeastern University China
IET Control Theory and Applications | Year: 2013

In this study,we deal with the output tracking control problemfor a class of switched non-linear systems in lower triangular form subject to constraints on the states. To prevent states from transgressing the constraints, we employ a barrier Lyapunov function (BLF), which grows to infinity when its arguments approach domain boundaries. Based on the simultaneous domination assumption, we design a continuous feedback controller for the switched system. Furthermore, we show that asymptotic tracking is achieved without violation of the constraints and all closed-loop signals remain bounded, when a mild requirement on the initial values is imposed. Finally, the effectiveness of the proposed results is demonstrated using two simulation examples. © The Institution of Engineering and Technology 2013.


Jin X.-Z.,Shenyang University | Yang G.-H.,Northeastern University China | Chang X.-H.,Bohai University
International Journal of Systems Science | Year: 2013

This article studies the problem of designing adaptive fault-tolerant H∞ tracking controllers for a class of aircraft flight systems against general actuator faults and bounded perturbations. A robust adaptive state-feedback controller is constructed by a stabilising controller gain and an adaptive control gain function. Using mode-dependent Lyapunov functions, linear matrix inequality-based conditions are developed to find the controller gain such that disturbance attenuation performance is optimised. Adaptive control schemes are proposed to estimate the unknown controller parameters on-line for unparametrisable stuck faults and perturbation compensations. Based on Lyapunov stability theory, it is shown that the resulting closed-loop systems can guarantee asymptotic tracking with H∞ performances in the presence of faults on actuators and perturbations. An application to a decoupled linearised dynamic aircraft system and its simulation results are given. © 2013 Copyright Taylor and Francis Group, LLC.


Liu Y.,Northeastern University China | Cheng Z.,Tsinghua University | Sun H.,Tsinghua University | Arandiyan H.,University of New South Wales | And 2 more authors.
Journal of Power Sources | Year: 2015

(Graph Presented). Co3O4 mesoporous nanosheets/three-dimensional graphene networks (Co3O4 MNSs/3DGNs) nanohybrids have been successfully synthesized and investigated as anode materials for sodium ion batteries (SIBs). Microstructure characterizations have been performed to confirm the 3DGNs and Co3O4 MNSs nanostructures. It has been found that the present Co3O4 MNSs/3DGNs nanohybrids exhibit better SIB performance with enhanced reversible capacity, good cycle performance and rate capability as compared to Co3O4 MNSs and Co3O4 nanoparticles. The improved electrochemical performance is considered due to the mesoporous nature of the products, the addition of 3DGNs, 3D assembled hierarchical architecture and decrease in volume expansion during cycling. Thus, SIB is considered as a low cost alternative to LIBs for large-scale electric storage applications. © 2014 Elsevier B.V. All rights reserved.


Shi X.,Liaoning University of Petroleum and Chemical Technology | Wei G.,Northeastern University China | Wei G.,CAS Shenyang International Center for Materials Physics
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

As an analytical method, the effective-field theory (EFT) is used to study an Ising spin system in a transverse magnetic field under a time oscillating longitudinal field. The effective-field equations of motion of the average magnetization are given for the square lattice (Z = 4). In the longitudinal field amplitude h0 / Z J-transverse field Γ / Z J plane, the phase boundary separating the dynamic ordered and the disordered phase also has been drawn, and there is no dynamical tricritical point on the dynamic phase transition boundary. The dependence of the critical temperature on the transverse field is calculated and phase diagrams are presented. We also make the compare results of EFT with that given by using the mean field theory (MFT). © 2010 Elsevier B.V. All rights reserved.


Feng Z.,Bohai University | Lam J.,University of Hong Kong | Yang G.-H.,Northeastern University China
International Journal of Robust and Nonlinear Control | Year: 2015

This paper is concerned with the problem of stability analysis for continuous-time/discrete-time systems with interval time-varying delay. Based on the idea of partitioning the delay interval into l nonuniform subintervals, new Lyapunov functionals are established. By utilizing the reciprocally convex approach to deal with the delay information in each subinterval, sufficient stability conditions are proposed in terms of linear matrix inequalities. Based on these criteria, the optimal partitioning method is given on the basis of the genetic algorithm. Finally, the reduced conservatism of the results in this paper is illustrated by numerical examples. Copyright © 2013 John Wiley & Sons, Ltd.


Sun J.,Northeastern University China | Tong W.P.,Northeastern University China | Zuo L.,Northeastern University China | Wang Z.B.,CAS Shenyang Institute of Metal Research
Materials and Design | Year: 2013

A nanostructured surface layer was fabricated on titanium layer of a Ti/Al clad sheet composite by means of the surface mechanical attrition treatment (SMAT). The low-temperature plasma nitriding treatment of the SMAT sample was investigated in comparison with the coarse-grained sample by using structural analysis (X-ray diffraction, scanning electron microscopy, and transmission electron microscopy) as well as mechanical and corrosion property measurements. Results showed that the nitriding kinetics of the SMAT sample with the nanostructured surface layer was greatly enhanced, so that the nitriding temperature could be as low as 550°C, which is significantly lower than the melting point of the aluminum layer on Ti/Al clad sheet (conventional nitriding can lead to melting of the aluminum layer due to higher temperature about 800°C). The nitrided layer of the SMAT sample was composed of nanostructured ε-TiN and γ-Ti2N phase with high supersaturation of nitrogen. The surface hardness and the hardened surface layer thickness as well as the wear and corrosion resistances of the nitrided SMAT sample were all substantially enhanced relative to the nitrided coarse-grained sample. © 2012 Elsevier Ltd.


Tan Y.,Zhejiang GongShang University | Liu S.,Northeastern University China
International Journal of Production Research | Year: 2014

This paper studies the steelmaking-refining-continuous casting (SRCC) scheduling problem with considering variable electricity price (SRCCSPVEP). SRCC is one of the critical production processes for steel manufacturing and energy intensive. Combining the technical rules used in iron-steel production practice, time-dependent electricity price is considered to reduce the electricity cost and the associate production cost. A decomposition approach is proposed for the SRCCSPVEP. Without considering the electrical factor, the first phase applies the mathematical programming method to determine the relative schedule plan for each cast. In the second phase, we formulate a scheduling problem of all casts subject to resource constraint and time-dependent electricity price. A heuristic algorithm combined with the constraint propagation is developed to solve this scheduling problem. To investigate and measure the performance of the proposed approach, numerous instances are randomly generated according to the collective data from a well-known iron-steel plant in China. Computational results demonstrate that our algorithm is very efficient and effective in providing high-quality scheduling plans, and the electricity cost can be reduced for the iron-steel plant. © 2013 Taylor & Francis.


Guo W.,Georgia Institute of Technology | Guo W.,Xiamen University | Xue X.,Georgia Institute of Technology | Xue X.,Northeastern University China | And 4 more authors.
Nano Letters | Year: 2012

We present a new approach to fabricate an integrated power pack by hybridizing energy harvest and storage processes. This power pack incorporates a series-wound dye-sensitized solar cell (DSSC) and a lithium ion battery (LIB) on the same Ti foil that has double-sided TiO 2 nanotube (NTs) arrays. The solar cell part is made of two different cosensitized tandem solar cells based on TiO 2 nanorod arrays (NRs) and NTs, respectively, which provide an open-circuit voltage of 3.39 V and a short-circuit current density of 1.01 mA/cm 2. The power pack can be charged to about 3 V in about 8 min, and the discharge capacity is about 38.89 μAh under the discharge density of 100 μA. The total energy conversion and storage efficiency for this system is 0.82%. Such an integrated power pack could serve as a power source for mobile electronics. © 2012 American Chemical Society.


Chang X.-H.,Bohai University | Chang X.-H.,Shenyang University | Yang G.-H.,Northeastern University China
IEEE Transactions on Industrial Electronics | Year: 2014

This paper is concerned with the problem of nonfragile H filtering for continuous-time Takagi-Sugeno (T-S) fuzzy systems. The filter to be designed is assumed to have two types of multiplicative gain variations. First, two relaxed H filtering analysis conditions are proposed based on useful linear matrix inequality preliminaries. Whereafter, the results are exploited to derive sufficient conditions for designing a nonfragile H filter, which guarantees a prescribed H performance of the filtering error system. Compared with the existing results, the proposed design methods not only suit for a standard form of the fuzzy filter but also give more relaxed design conditions. Finally, simulation examples will be given to show the efficiency of the proposed design methods. © 2013 IEEE.


Chang X.-H.,Bohai University | Chang X.-H.,Shenyang University | Yang G.-H.,Northeastern University China
IEEE Transactions on Automatic Control | Year: 2014

This note investigates the problem of output feedback H∞ $ control for linear discrete-time systems. Three types of H ∞ controllers are considered, namely, static output feedback controllers, dynamic output feedback controllers, and observer-based output feedback controllers. New design conditions for the three type of output feedback controllers are introduced in terms of unified linear matrix inequality (LMI) representations, which guarantee the prescribed H∞ performances of the closed-loop systems. In contrast to the existing LMI conditions for designing the output feedback H∞ controllers, the improvement of the proposed results over the existing ones is shown by theoretical proof and numerical example. © 1963-2012 IEEE.


Chang X.-H.,Bohai University | Yang G.-H.,Northeastern University China
Information Sciences | Year: 2014

This paper investigates the problem of non-fragile H∞ filter design for discrete-time Takagi-Sugeno (T-S) fuzzy systems. The filter to be designed is assumed to have two type of multiplicative gain variations. By introducing additional matrix variables, a relaxed H∞ filtering analysis criterion is presented for the fuzzy system based on the fuzzy Lyapunov function. A filter state transformation approach is adopted to design the non-fragile H∞ filter, and the filter gains are given in terms of the feasible solutions of a set of linear matrix inequalities (LMIs). A simulation example is given to show the efficiency of the proposed methods. © 2013 Published by Elsevier Inc.


Liu F.,Bohai University | Gao H.,Bohai University | Qiu J.,State Key Laboratory of Robotics and System | Qiu J.,Harbin Institute of Technology | And 3 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

This paper investigates the setpoints compensation for a class of complex industrial processes. Plants at the device layer are controlled by the local regulation controllers, and a multirate output feedback control approach for setpoints compensation is proposed such that the local plants can reach the dynamically changed setpoints and the given economic objective can also be tracked via certain economic performance index (EPI). First, a sampled-data multivariable output feedback proportional integral (PI) controller is designed to regulate the performance of local plants. Second, the outputs and control inputs of the local plants at the device layer are sampled at operation layer sampling time to form the EPI. Thus, the multirate problem is solved by a lifting method. Third, the static setpoints are generated by real-time optimization and the dynamic setpoints are calculated by the compensator according to the error between the EPI and objective at each operation layer step. Then, a networked case is studied considering unreliable data transmission described by a stochastic packet dropout model. Finally, a rougher flotation process model is employed to demonstrate the effectiveness of the proposed method. © 1982-2012 IEEE.


Kobayashi S.,Ashikaga Institute of Technology | Maruyama T.,Ashikaga Institute of Technology | Tsurekawa S.,Kumamoto University | Watanabe T.,Northeastern University China | Watanabe T.,Tohoku University
Acta Materialia | Year: 2012

The effect of grain boundary microstructure on the fracture resistance of sulfur-doped polycrystalline nickel was investigated using specimens with different grain boundary microstructures to reveal the usefulness of grain boundary engineering for control of segregation-induced intergranular brittle fracture of polycrystalline materials. The sulfur-doped polycrystalline nickel specimen with more homogeneous fine-grained structure and a higher fraction of low-Σ coincidence site lattice (CSL) boundaries shows higher fracture resistance than the specimen with coarse-grained structure and a lower fraction of low-Σ CSL boundaries. It was found that high-energy random boundaries play a key role as the preferential crack path in fracture processes. The resistance to sulfur segregation-induced intergranular brittle fracture was evaluated by analyzing the fractal dimension of random boundary connectivity in the polycrystalline nickel specimens studied. The fractal dimension of random boundary connectivity decreases with increasing fraction of low-Σ CSL boundaries, resulting in the generation of a higher fracture resistance by restricting more frequent branching and deflection of propagating crack path along random boundaries from the main crack. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Chang X.-H.,Bohai University | Yang G.-H.,Northeastern University China
Fuzzy Sets and Systems | Year: 2011

This work is concerned with the observer-based H∞ control synthesis problem of discrete-time Takagi-Sugeno (T-S) fuzzy systems with external disturbances. The objective is to find a new way to design the controller and observer guaranteeing a prescribed H∞ performance of the fuzzy system. By the descriptor representation approach, two new conditions for observer-based H∞ control synthesis are proposed based on various Lyapunov function candidates, which are in the form of linear matrix inequalities (LMIs). A numerical example will be given to show the efficiency of the proposed method. © 2011 Elsevier B.V. © 2011 Elsevier B.V. All rights reserved.


Chang X.-H.,Bohai University | Yang G.-H.,Northeastern University China
International Journal of Innovative Computing, Information and Control | Year: 2011

This paper further studies stabilization and state feedback H∞ control conditions for discrete T-S fuzzy systems. By extending a nonquadratic Lyapunov function and applying a nonparallel distributed compensation (non-PDC) control law, first a relaxed stabilization conclusion is presented that is an extension of some previous results in the literature, then a sufficient condition which can guarantee the existence of state feedback H∞ controllers for the T-S fuzzy systems is proposed. In comparison with the existing results, the proposed conditions not only provide more relaxation but also ensure better H∞ performances. Finally, the validity and applicability of the proposed results are successfully demonstrated through two numerical examples. ICIC International © 2011.


Shi X.,Liaoning University of Petroleum and Chemical Technology | Shi X.,Northeastern University China | Zhao J.,Liaoning University of Petroleum and Chemical Technology | Xu X.,Liaoning University of Petroleum and Chemical Technology
Physica A: Statistical Mechanics and its Applications | Year: 2015

The mean-field theory (MFT) is used to study the dynamical response of the mixed spin-1 and spin-3/2 Ising model with Fe4N structure in the presence of a sinusoidal oscillating magnetic field. The Glauber dynamic is used to describe the time evolution of the system and the mean-field dynamic equations are given. Dynamic phase transition diagrams are presented in the T/|J| - h0/|J| plane. The dependence of the phase diagram on single-ion anisotropy strengths is also studied by the MFT. Besides second-order phase transition, lines of first-order phase transition, the dynamic tricritical point and the critical end point are found. In particular, the system exhibits first-order-order phase transitions, which cannot be found in previous studies in the mixed spin-1 and spin-3/2 Ising model using the MFT. © 2014 Elsevier B.V. All rights reserved.


Chang X.-H.,Bohai University | Yang G.-H.,Northeastern University China
Signal Processing | Year: 2012

This paper is concerned with the problem of designing non-fragile H filters for a class of nonlinear continuous-time systems. The considered nonlinear plant is represented by a TakagiSugeno (TS) fuzzy model. Attention is focused on the design of a filter such that the filtering error system guarantees a prescribed H performance level with D stability constraints, where the filter to be designed is assumed to be with multiplicative gain variations. A sufficient condition for the non-fragile H filter design is proposed in terms of linear matrix inequalities (LMIs). When these LMIs are feasible, an explicit expression of a desired H fuzzy filter is given. A simulation example will be given to show the efficiency of the proposed design methods. © 2011 Elsevier B.V. All Rights Reserved.


Chang X.-H.,Bohai University | Yang G.-H.,Northeastern University China
Asian Journal of Control | Year: 2011

This paper addresses robust constrained model predictive control (MPC) for a class of nonlinear systems with structured time-varying uncertainties. First, the Takagi-Sugeno (T-S) fuzzy model is employed to represent a nonlinear system. Then, we develop some techniques for designing fuzzy control which guarantees the system stabilization subject to input and output constraints. Both parallel and nonparallel distributed compensation control laws (PDC and non-PDC) are considered. Sufficient conditions for the solvability of the controller design problem are given in the form of linear matrix inequalities. A simulation example is presented to illustrate the design procedures and performances of the proposed methods. © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.


Fu R.,Yanshan University | Wang H.,Northeastern University China | Zhao W.,Louisiana State University
Expert Systems with Applications | Year: 2016

Driver's states in successive time slices are not independent, especially, fatigue is one of a cognitive state that is developing over time. Meanwhile, driver fatigue is also influenced by some corresponding contextual information at a certain time. In such case, classifying driving state at each time slice separately from it in before and after time slices obviously has less meaning. Therefore, a dynamic fatigue detection model based on Hidden Markov Model (HMM) is proposed in this paper. Driver fatigue can be estimated by this model in a probabilistic way using various physiological and contextual information. Electroencephalogram (EEG), Electromyogram (EMG), and respiration signals were simultaneously recorded by wearable sensors and sent to computer by Bluetooth during the real driving. From these physiological information, fatigue likelihood can be achieved using kernel distribution estimate at different time sections. Contextual information offered by specific environmental factors were used as prior of fatigue. As time proceeds, the posterior of fatigue can be gotten dynamically by this HMM-based fatigue recognition method. Based on the results of the method in this paper, it shows that it provides an effective way in detecting driver fatigue. © 2016 Elsevier Ltd


Chang X.,Bohai University | Yang G.,Northeastern University China
Journal of Control Theory and Applications | Year: 2013

This paper deals with H-infinity filtering of discrete-time systems with polytopic uncertainties. The uncertain parameters are supposed to reside in a polytope. By using the parameter-dependent Lyapunov function approach and introducing some slack matrix variables, a new sufficient condition for the H-infinity filter design is presented in terms of solutions to a set of linear matrix inequalities (LMIs). In contrast to the existing results for H-infinity filter design, the main advantage of the proposed design method is the reduced conservativeness. An example is provided to demonstrate the effectiveness of the proposed method. © 2013 South China University of Technology, Academy of Mathematics and Systems Science, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.


Niu B.,Northeastern University China | Niu B.,Bohai University | Zhao J.,Northeastern University China
Systems and Control Letters | Year: 2013

In this paper, we investigate the output tracking control problem of constrained nonlinear switched systems in lower triangular form. First, when all the states are subjected to constraints, we employ a Barrier Lyapunov Function (BLF), which grows to infinity whenever its arguments approach some finite limits, to prevent the states from violating the constraints. Based on the simultaneous domination assumption, we design a continuous feedback controller for the switched system, which guarantees that asymptotic output tracking is achieved without transgression of the constraints and all closed-loop signals remain bounded, provided that the initial states are feasible. Then, we further consider the case of asymmetric time-varying output constraints by constructing an appropriate BLF. Finally, the effectiveness of the proposed results is demonstrated with a numerical example. © 2013 Elsevier B.V. All rights reserved.


Zhang X.,Northeastern University China | Zhang X.,CAS Institute of Theoretical Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

The current observational data imply that the universe would end with a cosmic doomsday in the holographic dark energy model. However, unfortunately, the big-rip singularity will ruin the theoretical foundation of the holographic dark energy scenario. To rescue the holographic scenario of dark energy, we employ the braneworld cosmology and incorporate the extra-dimension effects into the holographic theory of dark energy. We find that such a mend could erase the big-rip singularity and leads to a de Sitter finale for the holographic cosmos. Therefore, in the holographic dark energy model, the extra-dimension recipe could heal the world. © 2009 Elsevier B.V. All rights reserved.


Liu H.,Northeastern University China | Xu Q.,Northeastern University China | Yan C.,CAS Shenyang Institute of Metal Research
Electrochemistry Communications | Year: 2013

The electrochemical corrosion of the graphite electrode for vanadium redox flow battery is investigated by on-line mass spectrometry analysis. The results show that CO2 and CO form and evolve more preferably than O 2 on the graphite anode, which lead to the electrochemical corrosion of the graphite electrode. Furthermore, the evolution rate of O2 is the highest one among evolved gases if the polarization potential becomes too positive. The oxidation of VO2 + on the graphite electrode in 2 M H2SO4 + 2 M VOSO4 hinders the carbon oxidation reaction and retards the electrochemical corrosion of the graphite electrode. © 2012 Elsevier B.V.


Hao L.,CAS Shenyang Institute of Metal Research | Zhang S.,Northeastern University China | Zhang S.,Laiwu Steel Group | Dong J.,CAS Shenyang Institute of Metal Research | Ke W.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2012

The evolution of rust on MnCuP weathering steel submitted to a simulated coastal atmosphere was investigated by corrosion weight gain, scanning electron microscopy, X-ray diffraction, and electrochemical methods. The results indicate that the higher corrosion rate during the first stage than that during the second stage is related closely to the rust composition and electrochemical properties. The corrosion rate evolution is caused by the formation of a protective rust layer with a higher relative amount of α-FeOOH. The rust initially enhances and then stabilizes the cathodic process, but the anodic process tends to be inhibited by the protective rust layer. © 2012.


Liu G.Q.,Northeastern University China | Wen L.,CAS Shenyang Institute of Metal Research | Liu Y.M.,Northeastern University China
Journal of Solid State Electrochemistry | Year: 2010

The spinel material LiNi 0.5Mn 1.5O 4 displays a remarkable property of high charge/discharge voltage plateau at around 4.7 V. It is a promising cathode material for new-generation lithium-ion batteries with high voltage. Recently, a lot of researches related to this material have been carried out. In this review we present a summary of these researches, including the structure, the mechanism of high voltage, and the latest developments in improving its electrochemical properties like rate ability and cycle performance at elevated temperature, etc. Doping element and synthesizing nanoscale material are effective ways to improve its rate ability. The novel battery systems, like LiNi 0.5Mn 1.5O 4/Li 5Ti 4O 12 with good electrochemical properties, are also in progress. © 2010 Springer-Verlag.


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.


Song R.,University of Science and Technology Beijing | Wei Q.,CAS Institute of Automation | Sun Q.,Northeastern University China
Neurocomputing | Year: 2015

In this paper, a novel adaptive dynamic programming (ADP) algorithm is developed to solve the nearly optimal finite-horizon control problem for a class of deterministic nonaffine nonlinear time-delay systems. The idea is to use ADP technique to obtain the nearly optimal control which makes the optimal performance index function close to the greatest lower bound of all performance index functions within finite time. The proposed algorithm contains two cases with respective different initial iterations. In the first case, there exists control policy which makes arbitrary state of the system reach to zero in one time step. In the second case, there exists a control sequence which makes the system reach to zero in multiple time steps. The state updating is used to determine the optimal state. Convergence analysis of the performance index function is given. Furthermore, the relationship between the iteration steps and the length of the control sequence is presented. Two neural networks are used to approximate the performance index function and compute the optimal control policy for facilitating the implementation of ADP iteration algorithm. At last, two examples are used to demonstrate the effectiveness of the proposed ADP iteration algorithm. © 2014 Elsevier B.V.


Xu J.-W.,Northeastern University China | Gao Z.-D.,Northeastern University China | Han K.,Northeastern University China | Liu Y.,Northeastern University | Song Y.-Y.,Northeastern University China
ACS Applied Materials and Interfaces | Year: 2014

Silver orthophosphate (Ag3PO4) is a low-band-gap photocatalyst that has received considerable research interest in recent years. In this work, the magnetic Ag3PO4/TiO2/Fe3O4heterostructured nanocomposite was synthesized. The nanocomposite was found to exhibit markedly enhanced photocatalytic activity, cycling stability, and long-term durability in the photodegradation of acid orange 7 (AO7) under visible light. Moreover, the antibacterial film prepared from Ag3PO4/TiO2/Fe3O4nanocomposite presented excellent bactericidal activity and recyclability toward Escherichia coli (E. coli) cells under visible-light irradiation. In addition to the intrinsic cytotoxicity of silver ions, the elevated bactericidal efficiency of Ag3PO4/TiO2/Fe3O4can be largely attributed to its highly enhanced photocatalytic activity. The photogenerated hydroxyl radicals and superoxide ions on the formed Ag/Ag3PO4/TiO2interfaces cause considerable morphological changes in the microorganisms cells and lead to the death of the bacteria. © 2014 American Chemical Society.


Zhang H.,Northeastern University China | Wei Q.,CAS Institute of Automation | Liu D.,CAS Institute of Automation
Automatica | Year: 2011

In this paper, a new iterative adaptive dynamic programming (ADP) method is proposed to solve a class of continuous-time nonlinear two-person zero-sum differential games. The idea is to use the ADP technique to obtain the optimal control pair iteratively which makes the performance index function reach the saddle point of the zero-sum differential games. If the saddle point does not exist, the mixed optimal control pair is obtained to make the performance index function reach the mixed optimum. Stability analysis of the nonlinear systems is presented and the convergence property of the performance index function is also proved. Two simulation examples are given to illustrate the performance of the proposed method. © 2010 Elsevier Ltd. All rights reserved.


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.


Cai X.,Northeastern University China | Liu C.,Laiwu Steel Group | Liu Z.,Northeastern University China
Materials and Design | Year: 2014

We investigate here the three-stage cooling process of dual phase (DP) steels with the prepositional ultra fast cooling (UFC) equipment, which is different with the DP production line, with UFC in the end. Two dimensional finite difference model (FEM) was used to calculate the temperature field during the cooling process and classical thermodynamic model is used to develop CCT diagram. The temperature field and phase transformation process are combined to predict the microstructure and the mechanical properties across the cross-section using the thermodynamic model and the empirical model. The experiments present good mechanical properties of DP steels, which proved the production of DP steels with the prepositional UFC equipment is feasible. © 2013 The Authors.


Liu J.,Harbin Institute of Technology | Yan D.L.,Northeastern University China
IEEE Transactions on Fuzzy Systems | Year: 2016

With the increasing popularity of XML for data representations, there is a lot of interest in searching XML data. Due to the structural heterogeneity and textual content's diversity of XML, it is daunting for users to formulate exact queries and search accurate answers. Therefore, approximate matching is introduced to deal with the difficulty in answering users' queries, and this matching could be addressed by first relaxing the structure and content of a given query and, then, looking for answers that match the relaxed queries. Ranking and returning the most relevant results of a query have become the most popular paradigm in XML query processing. However, the existing proposals do not adequately take structures into account, and they, therefore, lack the strength to elegantly combine structures with contents to answer the relaxed queries. To address this problem, we first propose a sophisticated framework of query relaxations for supporting approximate queries over XML data. The answers underlying this framework are not compelled to strictly satisfy the given query formulation; instead, they can be founded on properties inferable from the original query. We, then, develop a novel top-k retrieval approach that can smartly generate the most promising answers in an order correlated with the ranking measure. We complement the work with a comprehensive set of experiments to show the effectiveness of our proposed approach in terms of precision and recall metrics. © 1993-2012 IEEE.


Tang L.,Northeastern University China | Che P.,Northeastern University | Wang J.,Argonne National Laboratory
IEEE Transactions on Power Systems | Year: 2012

We investigate the corrective unit commitment problem to deal with disruption in power system operations caused by an unforeseen unit breakdown with stochastic duration. Since the original unit schedule is no longer feasible when a unit breaks down during operation, a corrective scheduling that provides an immediate response to such a disruption is needed to update the original schedule in time. The objective of the corrective scheduling is to minimize the generation cost and the deviation from the original schedule. The corrective scheduling problem is formulated as a mixed integer nonlinear programming model where the stochastic duration is expressed by tree-structured duration scenarios. The proposed variable splitting-based Lagrangian relaxation algorithm decomposes the problem into multiple single-unit subproblems and a linear programming-type artificial variable subproblem. Each single-unit subproblem is solved by a two-stage procedure. In the first stage, the generating level of the unit in each committed period is determined optimally. In the second stage, before the dynamic programming is called, an effective pre-processing technique based on optimality conditions is applied to speed up the procedure. The dual problem is solved by a bundle method. The numerical results show that the algorithm can find solutions very close to optimums within a reasonable time. © 1969-2012 IEEE.


Yuan Z.,Northeastern University China | Yang J.,Northeastern University China | Zhang Y.,Harbin Institute of Technology | Zhang X.,Northeastern University China
Energy | Year: 2015

In this paper, the response surface methodology is applied to optimize the operating conditions of μDMFC (micro direct methanol fuel cell). Three operating parameters, the methanol flow rate, the methanol concentration and the cell temperature are considered in this study, and the ranges of them are 0.5-1.5 ml min-1, 0.5-2.0 mol L-1 and 20-60 °C respectively. The individual effects of these operating parameters and the combined effects of multiple operating conditions on air-breathing cell performance are examined. Furthermore, a quadratic model is established to describe the maximum power density and open-circuit voltage as the response value. © 2014 Elsevier Ltd.


Zhang H.,Northeastern University China | Wang Z.,Northeastern University China | Liu D.,CAS Institute of Automation
IEEE Transactions on Neural Networks and Learning Systems | Year: 2014

Stability problems of continuous-time recurrent neural networks have been extensively studied, and many papers have been published in the literature. The purpose of this paper is to provide a comprehensive review of the research on stability of continuous-time recurrent neural networks, including Hopfield neural networks, Cohen-Grossberg neural networks, and related models. Since time delay is inevitable in practice, stability results of recurrent neural networks with different classes of time delays are reviewed in detail. For the case of delay-dependent stability, the results on how to deal with the constant/variable delay in recurrent neural networks are summarized. The relationship among stability results in different forms, such as algebraic inequality forms,\(M\)-matrix forms, linear matrix inequality forms, and Lyapunov diagonal stability forms, is discussed and compared. Some necessary and sufficient stability conditions for recurrent neural networks without time delays are also discussed. Concluding remarks and future directions of stability analysis of recurrent neural networks are given. © 2014 IEEE.


Ding J.,Northeastern University China | Chai T.,Northeastern University China | Wang H.,Northeastern University China | Wang H.,University of Manchester
IEEE Transactions on Neural Networks | Year: 2011

This paper presents a novel offline modeling for product quality prediction of mineral processing which consists of a number of unit processes in series. The prediction of the product quality of the whole mineral process (i.e., the mixed concentrate grade) plays an important role and the establishment of its predictive model is a key issue for the plantwide optimization. For this purpose, a hybrid modeling approach of the mixed concentrate grade prediction is proposed, which consists of a linear model and a nonlinear model. The least-squares support vector machine is adopted to establish the nonlinear model. The inputs of the predictive model are the performance indices of each unit process, while the output is the mixed concentrate grade. In this paper, the model parameter selection is transformed into the shape control of the probability density function (PDF) of the modeling error. In this context, both the PDF-control-based and minimum-entropy-based model parameter selection approaches are proposed. Indeed, this is the first time that the PDF shape control idea is used to deal with system modeling, where the key idea is to turn model parameters so that either the modeling error PDF is controlled to follow a target PDF or the modeling error entropy is minimized. The experimental results using the real plant data and the comparison of the two approaches are discussed. The results show the effectiveness of the proposed approaches. © 2010 IEEE.


Tang L.,Northeastern University China | Wang G.,Northeastern University China | Chen Z.-L.,University of Maryland University College
Operations Research | Year: 2014

We study an integrated charge batching and casting width selection problem arising in the continuous casting operation of the steelmaking process at Shanghai, China based Baosteel. This decision-making problem is not unique to Baosteel, It exists in every large iron and steel company in the world. We collaborated with Baosteel on this problem from 2006 to 2008 by developing and implementing a decision support system (DSS) that replaced their manual planning method. The DSS is still in active use at Baosteel. This paper describes the solution algorithms we developed and imbedded in the DSS. For the general problem that is strongly NP-hard, a column generation-based branch-and-price (B&P) solution approach is developed to obtain optimal solutions. By exploiting the problem structure, efficient dynamic programming algorithms are designed to solve the subproblems involved in the column generation procedure. Branching strategies are designed in a way that ensures that after every stage of branching the structure of the subproblems is preserved such that they can still be solved efficiently. We also consider a frequently occurring case of the problem where each steel grade is incompatible with any other grade. For this special case, a two-level polynomial-time algorithm is developed to obtain optimal solutions. Computational tests on a set of real production data as well as on a more diverse set of randomly generated problem instances show that our algorithms outperform the manual planning method that Baosteel used to use by a significant margin both in terms of tundish utilization for almost every case, and in terms of total cost for most cases. Consequently, by replacing their manual method with our DSS, the estimated benefits to Baosteel include an annual cost saving of about US 1.6 million and an annual revenue increase of about US 3.25 million.


Zhao Y.,Northeastern University China | Zikanov O.,University of Michigan | Krasnov D.,TU Ilmenau
Physics of Fluids | Year: 2011

Instability of a flow of an electrically conducting fluid in an annular channel is analyzed. Strong constant magnetic field is imposed in the axial direction. Similarly to toroidal duct experiments, the flow is driven by the azimuthal Lorentz force resulting from the interaction between the magnetic field and the radial electric currents created by a difference of electric potential imposed between the cylinders. The instability of the base flow, while clearly of centrifugal nature, is significantly different from the Dean instability detected earlier in hydrodynamic systems and similar MHD systems at low and moderate magnetic fields. Growing perturbations are oscillating and axisymmetric and consist of counter-rotating toroidal vortices arranged side by side in the radial direction and having meridional cross-sections in the form of elongated ellipses oriented slightly obliquely to the axial direction. Simulations of the secondary flow show an interesting feature of periodic transitions between two symmetric solutions. © 2011 American Institute of Physics.


Zhang X.,Northeastern University China | Pandey M.D.,University of Waterloo
Reliability Engineering and System Safety | Year: 2014

The paper presents a fairly efficient approximation for the computation of variance-based sensitivity measures associated with a general, n-dimensional function of random variables. The proposed approach is based on a multiplicative version of the dimensional reduction method (M-DRM), in which a given complex function is approximated by a product of low dimensional functions. Together with the Gaussian quadrature, the use of M-DRM significantly reduces the computation effort associated with global sensitivity analysis. An important and practical benefit of the M-DRM is the algebraic simplicity and closed-form nature of sensitivity coefficient formulas. Several examples are presented to show that the M-DRM method is as accurate as results obtained from simulations and other approximations reported in the literature. © 2013 Elsevier Ltd.


Zhang Y.,Northeastern University China | An J.,Northeastern University China | Li Z.,Northeastern University China | Wang H.,University of Manchester
Information Sciences | Year: 2013

In this paper, a new online monitoring approach is proposed for handling the dynamical multimode problem in the industrial processes. The contributions are as follows: (1) extracting method of the common characteristics from different modes is proposed; (2) nonlinear dynamic monitoring method is proposed; and (3) a new model analysis method is proposed. There are both similarity and dissimilarity in the underlying correlations of different modes. After two different subspaces are separated, models of the common and specific subspaces are built respectively. Then the common subspace and specific subspace are analyzed, where the monitoring process is carried out in each subspace. When the mode switches, the specific monitoring model is changed. The corresponding confidence regions are constructed according to their models respectively. The effectiveness of the proposed method has been demonstrated via simulated examples. © 2012 Elsevier Inc. All rights reserved.


Zhang C.,Northeastern University China | Wang H.,Northeastern University China | Wang H.,University of Manchester | Wu M.-H.,University of Derby
Integrated Computer-Aided Engineering | Year: 2013

This paper presents a novel expert system based on electroencephalogram (EEG) and demonstrates the process of knowledge acquisition and inference. As we known, the problem-solving mode of expert brains is: They judge the current situation (learn about the problem), and then generate operational decisions to solve problems. However, the experts have difficulty in explaining what they know and how they gain the knowledge. Their perfect performance may be difficult to replicate. The EEG signal may be one of the most predictive and reliable measurements to acquire the expert knowledge as it reflects directly human brain activity. It is supposed that EEG is a manifestation of the experts' thinking. By the analysis of EEG, we found the regularity of EEG features of the experts in a well-defined problem domain and used the features to reflect the learning and decision-making information of the expert brains to establish the EEG-based expert system. The knowledge base of the EEG-based expert system stores the features that reflect the learning and decision-making activities of the expert brains respectively. Based on the relationship between the two kinds of the EEG features, inference engine of the EEG-based expert system makes an inference to obtain the features that reflect the decisions of the experts. When we encounter the same problem, the brains make the same judgement (learning). After the EEG data acquisition, through the EEG-based expert system, we can get the expert decisions (operations). If we interpret the decisions into actual operations or control, we can solve the problem with the expert performance or control machines more intelligently. In this paper, game experiments have been designed. We used the solution to the operation problem of a game as the basis to establish the model of the EEG-based expert system. The inputs of the system are the collected EEG signals of the users. The outputs are the operations (decisions) of the experts. The results of the EEG analysis show that the activity appeared in the corresponding brain regions and the probability density function (PDF) of the EEG features is concentrated when the experts performed the task (playing the game). By using the sample entropy (SampEn) and Lempel-Ziv complexity (LZC) algorithm, the EEG features of the experts' learning activities and operating activities were extracted respectively. Then, with applying the probability density functions of the features to output PDF control, the mathematical model of the EEG-based expert system was established. In the EEG-based expert system, inference means controlling the feature vectors which reflect the users' learning information from the current situation to get the feature vectors which reflect the operating information of the experts. Finally, the expert system model has been tested on a simulated example and encouraging results have been obtained. The EEG-based expert system can forecast the operating features of the experts. The output of the EEG-based expert system is in accord with the expert mode and the operating curve represented by the physiological signal features can reflect the actual operating information. © 2013-IOS Press and the author(s).


Zhu X.-L.,Zhengzhou University of Light Industry | Wang Y.,Nanyang Technological University | Yang G.-H.,Northeastern University China
IET Control Theory and Applications | Year: 2010

The authors investigate the stability for continuous-time systems with interval time-varying delay. To deal with the non-linear time-varying coefficients derived from Jensen's integral inequality, a well-known feature of the sum of these coefficients is utilised. Combining with a delay partition method, the upper bound of the derivative of the Lyapunov functional can be estimated more tightly and expressed as a convex combination with respect to the reciprocal of the delay rather than the delay. New less conservative stability criteria are derived in terms of linear matrix inequalities. Numerical examples are given to illustrate the effectiveness of the proposed results. © 2010 The Institution of Engineering and Technology.


Zhu X.-L.,Northeastern University China | Zhu X.-L.,Zhengzhou University of Light Industry | Yang G.-H.,Northeastern University China
International Journal of Robust and Nonlinear Control | Year: 2010

This paper studies the problem of stability analysis for continuous-time systems with time-varying delay. By developing a delay decomposition approach, the information of the delayed plant states can be taken into full consideration, and new delay-dependent sufficient stability criteria are obtained in terms of linear matrix inequalities. The merits of the proposed results lie in their less conservatism, which are realized by choosing different Lyapunov matrices in the decomposed integral intervals and estimating the upper bound of some cross term more exactly. Numerical examples are given to illustrate the effectiveness and less conservatism of the proposed method. © 2009 John Wiley & Sons, Ltd.


Holmqvist S.,Lund University | Chutna O.,Lund University | Bousset L.,French National Center for Scientific Research | Aldrin-Kirk P.,Lund University | And 7 more authors.
Acta Neuropathologica | Year: 2014

The cellular hallmarks of Parkinson’s disease (PD) are the loss of nigral dopaminergic neurons and the formation of α-synuclein-enriched Lewy bodies and Lewy neurites in the remaining neurons. Based on the topographic distribution of Lewy bodies established after autopsy of brains from PD patients, Braak and coworkers hypothesized that Lewy pathology primes in the enteric nervous system and spreads to the brain, suggesting an active retrograde transport of α-synuclein (the key protein component in Lewy bodies), via the vagal nerve. This hypothesis, however, has not been tested experimentally thus far. Here, we use a human PD brain lysate containing different forms of α-synuclein (monomeric, oligomeric and fibrillar), and recombinant α-synuclein in an in vivo animal model to test this hypothesis. We demonstrate that α-synuclein present in the human PD brain lysate and distinct recombinant α-synuclein forms are transported via the vagal nerve and reach the dorsal motor nucleus of the vagus in the brainstem in a time-dependent manner after injection into the intestinal wall. Using live cell imaging in a differentiated neuroblastoma cell line, we determine that both slow and fast components of axonal transport are involved in the transport of aggregated α-synuclein. In conclusion, we here provide the first experimental evidence that different α-synuclein forms can propagate from the gut to the brain, and that microtubule-associated transport is involved in the translocation of aggregated α-synuclein in neurons. © 2014, Springer-Verlag Berlin Heidelberg.


Zhang Y.,Hefei University of Technology | Xiong Z.,Microsoft | Yang Z.,Northeastern University China | Wu F.,Microsoft
IEEE Transactions on Image Processing | Year: 2014

Time multiplexing (TM) and spatial neighborhood (SN) are two mainstream structured light techniques widely used for depth sensing. The former is well known for its high accuracy and the latter for its low delay. In this paper, we explore a new paradigm of scalable depth sensing to integrate the advantages of both the TM and SN methods. Our contribution is twofold. First, we design a set of hybrid structured light patterns composed of phase-shifted fringe and pseudo-random speckle. Under the illumination of the hybrid patterns, depth can be decently reconstructed either from a few consecutive frames with the TM principle for static scenes or from a single frame with the SN principle for dynamic scenes. Second, we propose a scene-adaptive depth sensing framework based on which a global or region-wise optimal depth map can be generated through motion detection. To validate the proposed scalable paradigm, we develop a real-time (20 fps) depth sensing system. Experimental results demonstrate that our method achieves an efficient balance between accuracy and speed during depth sensing that has rarely been exploited before. © 2013 IEEE.


Cheng H.,Northeastern University China | Chen H.,Texas State University
Journal of Manufacturing Science and Engineering, Transactions of the ASME | Year: 2014

Typical robot teaching performed by operators in industrial robot applications increases the operational cost and reduces the manufacturing efficiency. In this paper, an "adult" robot enabled learning method is proposed to solve such teaching problem. This method uses an "adult" robot with advanced sensing and decision-making capabilities to teach "child" robots in manufacturing automation. A Markov Decision Process (MDP) which aims to correct the "child" robot's tool position is formulated and solved using Q-Learning. The proposed algorithm was tested using a mobile robot platform with an in-hand camera (adult) to teach an industrial robot (child) to perform a high accuracy peg-in-hole process. The experimental results demonstrate very robust and stable performance. Because the calibration between the "adult" and "child" robots is eliminated, the flexibility of the proposed method is greatly increased. Hence it can be easily applied in industrial applications where a robot with limited sensing capabilities is installed. © VC 2014 by ASME.


Zhang Y.,Northeastern University China | Chai T.,Northeastern University China | Wang H.,Northeastern University China | Wang H.,University of Manchester
IEEE Transactions on Neural Networks | Year: 2011

This paper presents a novel nonlinear control strategy for a class of uncertain single-input and single-output discrete-time nonlinear systems with unstable zero-dynamics. The proposed method combines adaptive-network-based fuzzy inference system (ANFIS) with multiple models, where a linear robust controller, an ANFIS-based nonlinear controller and a switching mechanism are integrated using multiple models technique. It has been shown that the linear controller can ensure the boundedness of the input and output signals and the nonlinear controller can improve the dynamic performance of the closed loop system. Moreover, it has also been shown that the use of the switching mechanism can simultaneously guarantee the closed loop stability and improve its performance. As a result, the controller has the following three outstanding features compared with existing control strategies. First, this method relaxes the assumption of commonly-used uniform boundedness on the unmodeled dynamics and thus enhances its applicability. Second, since ANFIS is used to estimate and compensate the effect caused by the unmodeled dynamics, the convergence rate of neural network learning has been increased. Third, a one-to-one mapping technique is adapted to guarantee the universal approximation property of ANFIS. The proposed controller is applied to a numerical example and a pulverizing process of an alumina sintering system, respectively, where its effectiveness has been justified. © 2011 IEEE.


Spenza D.,University of Rome La Sapienza | Magno M.,ETH Zurich | Basagni S.,Northeastern University China | Benini L.,University of Rome La Sapienza | And 2 more authors.
Proceedings - IEEE INFOCOM | Year: 2015

Emerging wake-up radio technologies have the potential to bring the performance of sensing systems and of the Internet of Things to the levels of low latency and very low energy consumption required to enable critical new applications. This paper provides a step towards this goal with a twofold contribution. We first describe the design and prototyping of a wake-up receiver (WRx) and its integration to a wireless sensor node. Our WRx features very low power consumption (< 1.3μW), high sensitivity (up to - 55dBm), fast reactivity (wake-up time of 130μs), and selective addressing, a key enabler of new high performance protocols. We then present ALBA-WUR, a cross-layer solution for data gathering in sensing systems that redesigns a previous leading protocol, ALBA-R, extending it to exploit the features of our WRx. We evaluate the performance of ALBA-WUR via simulations, showing that the use of the WRx produces remarkable energy savings (up to five orders of magnitude), and achieves lifetimes that are decades longer than those obtained by ALBA-R in sensing systems with duty cycling, while keeping latencies at bay. © 2015 IEEE.


Li J.,Northeastern University China | Li J.,Hebei North University | Zhao J.,Northeastern University China
Systems and Control Letters | Year: 2013

This paper focuses on the passivity analysis and feedback passification for switched discrete-time linear systems using multiple storage functions under a certain switching law. Controllers and switching laws are designed based on complete and partial state measurements, respectively. Conditions for strict passivity of a switched discrete-time system are obtained without the requirement of strict passivity of subsystems. In the case of partial state measurements, dynamic output feedback controllers for subsystems are designed, and a switching law depending only on the state of the output feedback controllers is constructed to guarantee strict passivity of the closed-loop switched system. Finally, a numerical example is provided to demonstrate the feasibility of the theoretical results. © 2013 Elsevier B.V. All rights reserved.


Li Z.B.,Northeastern University China | Zhang Y.D.,CNRS Study of Microstructures, Mechanics and Material Sciences lab | Esling C.,CNRS Study of Microstructures, Mechanics and Material Sciences lab | Zhao X.,Northeastern University China | Zuo L.,Northeastern University China
Acta Materialia | Year: 2011

For Ni-Mn-Ga ferromagnetic shape memory alloys, a large magnetic-field-induced strain could be reached through the reorientation of martensitic variants in the martensite state. Owing to the collective and displacive nature of the austenite to martensite transformation, a certain orientation relationship (OR) between the parent and the product phase is required to minimize the transformation strain and the strain energy generated, which brings about self-accommodating groups of martensitic variants with specific orientation correlations. In this work, the microstructural and crystallographic characteristics of martensitic variants in a polycrystalline Ni50Mn30Ga20 alloy were investigated by electron backscatter diffraction analysis. With accurate orientation measurement on inherited martensitic variants, the local orientations of parent austenite grains were predicted using four classical OR for the martensitic transformation. Furthermore, a specific OR, namely the Pitsch relation with (1 0 1)A//(1 2̄ 10)7M and [1 0 1̄]A//[10 10 1]7M, was unambiguously determined by considering the magnitude of discontinuity between the lattices of the product and parent phases and the structural modulation of the incommensurate 7M modulated martensite. The present procedure to determine the OR, without recourse to the presence of retained austenite, is in general applicable to a variety of materials with modulated superstructure for insight into their martensitic transformation processes. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Li Z.,Northeastern University China | Zhang Y.,CNRS Study of Microstructures, Mechanics and Material Sciences lab | Esling C.,CNRS Study of Microstructures, Mechanics and Material Sciences lab | Zhao X.,Northeastern University China | Zuo L.,Northeastern University China
Acta Materialia | Year: 2011

For Ni-Mn-Ga ferromagnetic shape memory alloys, the characteristic features of modulated martensite (including the number/shape of constituent variants, the inter-variant orientation relationship and the geometrical distribution of variant interfaces) determine the attainability of the shape memory effect. In the present work, a comprehensive microstructural and crystallographic investigation has been conducted on a bulk polycrystalline Ni 50Mn28Ga22 alloy. As a first attempt, the orientation measurements by electron backscatter diffraction (EBSD) - using the precise information on the commensurate 5M modulated monoclinic superstructure (instead of the conventionally simplified non-modulated tetragonal structure) - were successfully performed to identify the crystallographic orientations on an individual basis. Consequently, the morphology of modulated martensite, the orientation relationships between adjacent variants and the characters of twin interfaces were unambiguously determined. With the thus-obtained full-featured image on the configuration of martensitic variants, the possibility of microstructural modification by proper mechanical "training" was further discussed. This new effort makes it feasible to explore the crystallographic/microstructural correlations in modulated martensite with high statistical reliability, which in turn provides useful guidance for optimizing the microstructure and shape memory performance. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Shen Z.,Wuhan University | Tong Q.,Northeastern University China
ICSPS 2010 - Proceedings of the 2010 2nd International Conference on Signal Processing Systems | Year: 2010

Cloud computing provides people the way to share distributed resources and services that belong to different organizations or sites. Since cloud computing share distributed resources via the network in the open environment, thus it makes security problems important for us to develop the cloud computing application. In this paper, we pay attention to the security requirements in cloud computing environment. We proposed a method to build a trusted computing environment for cloud computing system by integrating the trusted computing platform into cloud computing system. We propose a model system in which cloud computing system is combined with trusted computing platform with trusted platform module. In this model, some important security services, including authentication, confidentiality and integrity, are provided in cloud computing system. © 2010 IEEE.


Zhang Y.,Northeastern University China | Gao Q.,Northeastern University China | Gao L.,University of Massachusetts Amherst | Wang C.,Northeastern University China
Journal of Grid Computing | Year: 2012

Iterative computation is pervasive in many applications such as data mining, web ranking, graph analysis, online social network analysis, and so on. These iterative applications typically involve massive data sets containing millions or billions of data records. This poses demand of distributed computing frameworks for processing massive data sets on a cluster of machines. MapReduce is an example of such a framework. However, MapReduce lacks built-in support for iterative process that requires to parse data sets iteratively. Besides specifying MapReduce jobs, users have to write a driver program that submits a series of jobs and performs convergence testing at the client. This paper presents iMapReduce, a distributed framework that supports iterative processing. iMapReduce allows users to specify the iterative computation with the separated map and reduce functions, and provides the support of automatic iterative processing within a single job. More importantly, iMapReduce significantly improves the performance of iterative implementations by (1) reducing the overhead of creating new MapReduce jobs repeatedly, (2) eliminating the shuffling of static data, and (3) allowing asynchronous execution of map tasks. We implement an iMapReduce prototype based on Apache Hadoop, and show that iMapReduce can achieve up to 5 times speedup over Hadoop for implementing iterative algorithms. © 2012 Springer Science+Business Media B.V.


Song H.,State University of New York at Buffalo | Guo L.,Fudan University | Liu Z.,Fudan University | Liu K.,State University of New York at Buffalo | And 6 more authors.
Advanced Materials | Year: 2014

A fundamental strategy is developed to enhance the light-matter interaction of ultra-thin films based on a strong interference effect in planar nanocavities, and overcome the limitation between the optical absorption and film thickness of energy harvesting/conversion materials. This principle is quite general and is applied to explore the spectrally tunable absorption enhancement of various ultra-thin absorptive materials including 2D atomic monolayers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Yu J.,Northeastern University China | Xu L.D.,Northeastern University China | Bi Z.,Indiana University - Purdue University Fort Wayne | Wang C.,Northeastern University China
IEEE Transactions on Automation Science and Engineering | Year: 2014

One of the tasks in assembly planning is to create the exploded views for the visualization purpose and the verification of assembly plans. In this paper, we introduce how to generate exploded views automatically from an assembly model. To increase the level of automation, a new relational matrix called extended interference matrix (EIM) is used to represent the assembly relations among constitutive parts. Information in an EIM is used to create the exploded views. An innovative method is developed to generate the exploded views based on the assembly sequences and EIMs. The corresponding Application Programming Interface (API) to the Unigraphics software has been developed as an integration of the algorithm with the CAD software tool. The assembly model of a gear reducer is used as a case study. © 2013 IEEE.


Tian H.,Tianjin Polytechnic University | Wang A.,Northeastern University China
ISIJ International | Year: 2010

Fault diagnosis plays an important role during the process of blast furnace ironmaking for producing safety. In this paper the important parameters of puddling process are selected as judgments criterions of fault diagnosis by analyzing the changes of these parameters. Support vector machine (SVM) is used to establish the fault diagnosis model for its suitable characters for fault classification. But the stability and accuracy of model based on single SVM could not meet the needs of practical ironmaking. Therefore, a SVM ensemble based on bagging is presented to establish a novel fault diagnosis system. The real-time producing data are collected in 5# blast furnace of a steel enterprise for training and testing the fault diagnosis models with single SVM and SVM ensemble. The experiments about the comparison between single SVM and SVM ensemble and about the SVM ensembles with different number of individual SVM are made. The experimental results demonstrate that the performance of novel fault diagnosis system based on SVM ensemble is better than the one based on single SVM, and the best fault diagnosis system that can meet the practical needs of ironmaking is found. © 2010 ISIJ.


Shi W.,Northeastern University China | Wei W.,Xi'an Jiaotong University
Journal of Convergence Information Technology | Year: 2011

We modified the multi-agent negotiation test-bed which was proposed by Collins et al. In 2004, Jaiswal et al. have modified Collins's scheme, but Jaiswal's scheme still has some security weaknesses: such as replay data attack and DOS (denial-of-service) attack, anonymity disclosure, collision between customers and a certain supplier. So the proposed protocol tries to reduce DOS attack and avoids replay data attack by providing ticket token and deal sequence number to the supplier. It utilizes efficient LPN-based authentication method to accomplish lightweight authentication. And it publishes an interpolating polynomial for sharing the determination process data and avoids collusion between a customer and a certain supplier. Also the proposed scheme relaxes the trust assumptions for three-party in Jaiswal's scheme. According to comparison and analysis with other protocols, our proposed protocol shows good security and less computation cost.


Li P.,Huaqiao University | Li P.,Northeastern University China | Yang G.,Northeastern University China
Journal of Control Theory and Applications | Year: 2011

This paper presents a novel control method for accommodating actuator faults in a class of multiple-input multiple-output (MIMO) nonlinear uncertain systems. The designed control scheme can tolerate both the time-varying lock-in-place and loss of effectiveness actuator faults. In each subsystem of the considered MIMO system, the controller is obtained from a backstepping procedure; an adaptive fuzzy approximator with minimal learning parameterization is employed to approximate the package of unknown nonlinear functions in each design step. Additional control effort is taken to deal with the approximation error and external disturbance together. It is proven that the closed-loop stability and desired tracking performance can be guaranteed by the proposed control scheme. An example is used to show the effectiveness of the designed controller. © 2011 South China University of Technology, Academy of Mathematics and Systems Science, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.


Che W.-W.,Shenyang University | Yang G.-H.,Northeastern University China
International Journal of Control, Automation and Systems | Year: 2011

The non-fragile dynamic output feedback H∞ controller design problem is investigated. The controller to be designed is assumed to be with additive gain variations. A two-step procedure is proposed to develop sufficient conditions for the non-fragile H 8 controller design by employing the structured vertex separator. A comparison between the proposed and the existing controller design methods is provided, and a numerical example is carried out to support the theoretical findings. © ICROS, KIEE and Springer 2011.


Gong P.,Beijing Institute of Technology | Li P.,Beijing Institute of Technology | Shi W.,Northeastern University China
Nonlinear Dynamics | Year: 2012

To guarantee secure communication, many maps-based key agreement protocols have been proposed. Due to inherent tamper-resistance, most of them are based on smart cards. Unfortunately, the cost of cards and readers makes these protocols costly. In the real world, common storage devices, such as universal serial bus (USB) thumb drives, portable HDDs, mobile phones, and laptop or desktop PCs, are widely used, and they are much cheaper or more convenient for storing user authentication information. These devices do not provide tamper-resistance; it is a challenge to design a secure authentication protocol using these kinds of memory devices. In this paper, we will propose a maps-based key agreement protocol without using smart cards. According to our analysis, the proposed protocol guarantees mutual authentication, and also resists different attacks. Therefore, our protocol is suitable even for practical applications. © Springer Science+Business Media Dordrecht 2012.


Zou D.,Northeastern University China | Gao L.,Northeastern University China | Li S.,University of South Australia | Wu J.,Northeastern University China
Applied Soft Computing Journal | Year: 2011

This paper proposes a novel global harmony search algorithm (NGHS) to solve 0-1 knapsack problems. The proposed algorithm includes two important operations: position updating and genetic mutation with a small probability. The former enables the worst harmony of harmony memory to move to the global best harmony rapidly in each iteration, and the latter can effectively prevent the NGHS from trapping into the local optimum. Computational experiments with a set of large-scale instances show that the NGHS can be an efficient alternative for solving 0-1 knapsack problems. © 2010 Elsevier B.V. All rights reserved.


Wang L.,Northeastern University China | Yung N.H.C.,University of Hong Kong
IEEE Transactions on Intelligent Transportation Systems | Year: 2012

In this paper, the problem of human detection in crowded scenes is formulated as a maximum a posteriori problem, in which, given a set of candidates, predefined 3-D human shape models are matched with image evidence, provided by foreground extraction and probability of boundary, to estimate the human configuration. The optimal solution is obtained by decomposing the mutually related candidates into unoccluded and occluded ones in each iteration according to a graph description of the candidate relations and then only matching models for the unoccluded candidates. A candidate validation and rejection process based on minimum description length and local occlusion reasoning is carried out after each iteration of model matching. The advantage of the proposed optimization procedure is that its computational cost is much smaller than that of global optimization methods, while its performance is comparable to them. The proposed method achieves a detection rate of about 2% higher on a subset of images of the Caviar data set than the best result reported by previous works. We also demonstrate the performance of the proposed method using another challenging data set. © 2011 IEEE.


Che W.-W.,Shenyang University | Yang G.-H.,Northeastern University China
International Journal of Systems Science | Year: 2013

This article studies the quantised H∞ filtering problem for continuous-time systems with a type of dynamic quantisers, which are conjuncted with static quantisers via dynamic scalings. The static quantiser ranges are fully considered here for practical transmission channels requirements. A quantised H∞ filter design strategy is proposed, where a convex optimisation method is developed to minimise static quantiser ranges. The resulting design guarantees that the quantised augmented system is asymptotically stable and with a prescribed H∞ performance bound. The effectiveness of the proposed filter design method is demonstrated by a numerical example. © 2013 Copyright Taylor and Francis Group, LLC.


Chen M.-L.,Northeastern University China | An M.-I.,Northeastern University China | An M.-I.,Korea University
Talanta | Year: 2012

A novel adsorbent was developed by coating Mg-FeCO 3 layered double hydroxides (LDHs) on cellulose fibre. The LDHs take up significant amount of selenite and selenate in a wide pH range with similar sorption capacities (pH 3.8-8.0 for selenite and pH 5.8-7.0 for selenate). A mini-column packed with Mg-FeCO 3 LDHs layer coated cellulose fibre particles was incorporated into a sequential injection system for uptake of selenite at pH 6.0. The retained selenite was afterwards collected with 70 μL of 0.8%(m/v) NaOH as eluent, followed by hydride generation and atomic fluorescence spectrometric detection. Total inorganic selenium was adsorbed at pH 6.0 by the LDHs-cellulose fibre mini-column after selenate was pre-reduced to selenite by 2.0 mol L -1 HCl at 80 °C, and selenium speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 13.3 was derived with a detection limit of 11 ng L -1 within a linear range of 0.04-4.0 μg L -1. A relative standard deviation (RSD) of 3.3% (0.5 μg L -1, n = 11) was achieved. The procedure was validated by analyzing selenium in a certified reference material GBW 10010 (rice), and speciation of inorganic selenium in natural water samples. © 2012 Elsevier B.V. All rights reserved.


Zou D.,Northeastern University China | Gao L.,Northeastern University China | Wu J.,Northeastern University China | Li S.,University of South Australia
Neurocomputing | Year: 2010

In this paper, we use a recently proposed algorithm-novel global harmony search (NGHS) algorithm to solve unconstrained problems. The NGHS algorithm includes two important operations: position updating and genetic mutation with a low probability. The former can enhance the convergence of the NGHS, and the latter can effectively prevent the NGHS from being trapped into the local optimum. Based on a large number of experiments, the NGHS has demonstrated stronger convergence and stability than original harmony search (HS) algorithm and its two improved algorithms (IHS and SGHS). © 2010 Elsevier B.V.


Chunmiao Y.,Northeastern University China | Dezheng H.,Liaoning Nonferrous Metal Prospecting Institute | Chang L.,Shenyang Jianzhu University | Gang L.,Northeastern University China
Journal of Hazardous Materials | Year: 2013

The minimum temperature at which dust layers or deposits ignite is considered to be very important in industries where smoldering fires could occur. Experiments were conducted on the self-ignition behavior of magnesium powder layers. The estimated effective thermal conductivity k for modeling is 0.17Wm-1K-1. The minimum ignition temperature (MIT) of magnesium powder layers for four different particle sizes: 6, 47, 104 and 173μm, are also determined in these experiments. A model was developed describing temperature distribution and its change over time while considering the melting and boiling of magnesium powder. Parameter analysis shown that increasing particle size from 6 to 173μm increased MIT from 710 to 760K, and increased thickness of the dust layer led to a decreased MIT. The calculation termination time more than 5000s didn't significantly impact MIT. Comparing predicted and experimental data showed satisfactory agreement for MIT of magnesium powder layers at various particle sizes. According to the ignition process of magnesium powder layer, a meaningful definition for the most sensitive ignition position (MSIP) was proposed and should be taken into consideration when preventing smoldering fires induced by hot plates. © 2012 Elsevier B.V.


Jiang X.C.,University of New South Wales | Chen C.Y.,University of New South Wales | Chen C.Y.,Northeastern University China | Chen W.M.,University of New South Wales | Yu A.B.,University of New South Wales
Langmuir | Year: 2010

This study discusses the function of citrate ions in the synthesis of silver nanoplates through a synergetic reduction approach in ambient conditions. It was found that the citrate ions can play multiple roles in the synthesis process, including a reducing agent, a stabilizer, and a complex agent, and they show some unique features under the reported conditions. The reducing ability of these citrate ions was shown to be weaker than that of sodium borohydride and/or L-ascorbic acid used in the same system. The stability in the shape/size control of silver particles is weaker than that of other surfactants tested in the present system, such as bis(2-ethylhexyl)sulfosuccinate (AOT) and thiols. Citrate ions could form a silver complex with silver ions as [Ag2 + ⋯ citrate] or [Ag3(C6H 5O7)n+1]3n-, as confirmed by electrospray ionization (ESI) mass spectrometry and the kinetic analysis that the molar ratio of citric acid or sodium citrate to silver ions can greatly influence the reaction rate and, hence, the particle growth of silver nanoparticles. Such a complexing effect is further confirmed by the use of chelating ions (e.g., [Fe(CN)6]4-) to form Ag n[Fe(CN)6]4-, which can largely influence the synthesis of silver nanoparticles. These results show some formation results of generating silver nanoplates involving citrate ions, which are useful in the shape-controlled synthesis of other metallic nanoparticles with desirable functionalities. © 2010 American Chemical Society.


Lu F.-Q.,Northeastern University China | Huang M.,Northeastern University China | Ching W.-K.,University of Hong Kong | Siu T.K.,Macquarie University
Information Sciences | Year: 2013

In this paper, we propose a novel Two-level Particle Swarm Optimization (TLPSO) to solve the credit portfolio management problem. A two-date credit portfolio management model is considered. The objective of the manager is to minimize the maximum expected loss of the portfolio subject to a given consulting budget constraint. The captured problem is very challenging due to its hierarchical structure and its time complexity, so the TLPSO is designed for the credit portfolio management model. The TLPSO has two searching processes, namely, "internal-search", the searching process of the maximization problem and "external-search", the searching process of the minimization problem. The performance of TLPSO is then compared with both the Genetic Algorithm (GA) and the Particle Swarm Optimization (PSO), in terms of efficient frontiers, fitness values, convergence rates, computational time consumption and reliability. The experiment results show that TLPSO is more efficient and reliable for the credit portfolio management problem than the other tested methods. © 2013 Elsevier Inc. All rights reserved.


Jiang S.-F.,Fuzhou University | Zhang C.-M.,Northeastern University China | Zhang S.,Shenyang Jianzhu University
Expert Systems with Applications | Year: 2011

It is proposed in this paper a novel two-stage structural damage detection approach using fuzzy neural networks (FNNs) and data fusion techniques. The method is used for structural health monitoring and damage detection, particularly for cases where the measurement data is enormous and with uncertainties. In the first stage of structural damage detection, structural modal parameters derived from structural vibration responses are fed into an FNN as the input. The output values from the FNN are defuzzified to produce a rough structural damage assessment. Later, in the second stage, the values output from three different FNN models are input directly to the data fusion center where fusion computation is performed. The final fusion decision is made by filtering the result with a threshold function, hence a refined structural damage assessment of superior reliability. The proposed approach has been applied to a 7-degree of freedom building model for structural damage detection, and proves to be feasible, efficient and satisfactory. Furthermore, the simulation result also shows that the identification accuracy can be boosted with the proposed approach instead of FNN models alone. © 2010 Elsevier Ltd. All rights reserved.


Li T.-F.,Northeastern University China | Zhao J.,Northeastern University China | Dimirovski G.M.,Dogus University | Dimirovski G.M.,Ss. Cyril and Methodius University of Skopje
Journal of the Franklin Institute | Year: 2011

This paper considers the stability and L2-gain for a class of switched neutral systems with time-varying discrete and neutral delays. Some new delay-dependent sufficient conditions for exponential stability and weighted L2-gain are developed for a class of switching signals with average dwell time. These conditions are formulated in terms of linear matrix inequalities (LMIs) and are derived by employing free weighting matrices method. As a special case of such switching signals, we can obtain exponential stability and normal L2-gain under arbitrary switching signals. Finally, two numerical examples are given to illustrate the effectiveness of the theoretical results. © 2011 The Franklin Institute.


Jin X.-Z.,Shenyang University | Yang G.-H.,Northeastern University China | Che W.-W.,Shenyang University
IEEE Transactions on Neural Networks and Learning Systems | Year: 2012

This paper deals with a class of complex networks with nonideal coupling networks, and addresses the problem of asymptotic synchronization of the complex network through designing adaptive pinning control and coupling adjustment strategies. A more general coupled nonlinearity is considered as perturbations of the network, while a serious faulty network named deteriorated network is also proposed to be further study. For the sake of eliminating these adverse impacts for synchronization, indirect adaptive schemes are designed to construct controllers and adjusters on pinned nodes and nonuniform couplings of un-pinned nodes, respectively. According to Lyapunov stability theory, the proposed adaptive strategies are successful in ensuring the achievement of asymptotic synchronization of the complex network even in the presence of perturbed and deteriorated networks. The proposed schemes are physically implemented by circuitries and tested by simulation on a Chua's circuit network. © 2012 IEEE.


Wang X.,Northeastern University China | Wong T.N.,University of Hong Kong | Fan Z.-P.,Northeastern University China
Expert Systems with Applications | Year: 2013

It is now very popular for companies to collaborate as a global supply chain (GSC) for their business benefits. Many companies are inclined to outsource manufacturing, logistics and business activities globally. The senior managers of companies are faced with more complicated and dynamic situations to make decisions than ever before. They not only have to consider the internal factors including production, inventory, and financial status, but also have to take into account the external factors such as policies, market forces, competitive behaviors, etc. To survive in today's fierce market environment, it has become increasingly important for companies to find ways to combine the multi-source decision knowledge, and utilize it to make sound decisions across the organizational boundaries. In this paper, a rule-based ontology reasoning method is proposed to support decision makings and improve industrial practices for companies in the dynamic and heterogeneous GSC context. A shared GSC ontology is developed to describe the heterogeneous internal and external decision knowledge of the GSC companies and the dynamic market environments. It is contributed in enabling a semantic interoperable decision-making environment, along with the decision knowledge being evolved timely. In addition, semantic rules serving as decision requirements are developed to reason the shared GSC ontology to support the complicated and sound decision-makings, and also to provide suggestions on improving their industrial practices. A case study in China's iron and steel industry is introduced to justify the feasibility and effectiveness of the proposed ontology-based approaches. © 2013 Elsevier Ltd. All rights reserved.


Xiao C.,University of New South Wales | Wang W.,University of New South Wales | Lin X.,University of New South Wales | Yu J.X.,Chinese University of Hong Kong | Wang G.,Northeastern University China
ACM Transactions on Database Systems | Year: 2011

With the increasing amount of data and the need to integrate data from multiple data sources, one of the challenging issues is to identify near-duplicate records efficiently. In this article, we focus on efficient algorithms to find a pair of records such that their similarities are no less than a given threshold. Several existing algorithms rely on the prefix filtering principle to avoid computing similarity values for all possible pairs of records. We propose new filtering techniques by exploiting the token ordering information; they are integrated into the existing methods and drastically reduce the candidate sizes and hence improve the efficiency. We have also studied the implementation of our proposed algorithm in stand-alone and RDBMSbased settings. Experimental results show our proposed algorithms can outperform previous algorithms on several real datasets. © 2011 ACM.


Jin X.-Z.,Shenyang University | Yang G.-H.,Northeastern University China | Ye D.,Northeastern University China
Information Sciences | Year: 2013

This paper investigates the problem of insensitive reliable H ∞ filter designs for linear time-invariant continuous-time systems against sensor faults and filter coefficient variations. The considered faults are more general state-dependent bias/stuck-sensor faults. Based on mode-dependent Lyapunov functions, a novel insensitive reliable H ∞ filter is constructed in the framework of linear matrix inequalities (LMIs) technique to guarantee the stability and optimize the expanded H∞ performance index of the filtering error system. Moreover, some filter parameter functions are introduced to compensate the effect of sensor faults, as well as to eliminate the filter coefficient variations. The relationship among performance degradation of systems, sensor fault and coefficient variation compensations is clearly demonstrated by LMIs. A numerical example is carried out to illustrate the effectiveness and superiority of the proposed design method. © 2012 Elsevier Inc. All rights reserved.


Wang X.,University of Hong Kong | Wang X.,Northeastern University China | Wong T.N.,University of Hong Kong | Wang G.,University of Hong Kong
Expert Systems with Applications | Year: 2012

A virtual enterprise (VE) is a dynamic alliance of companies collaborating for the accomplishment of a specific business goal. To establish a VE, it is very important for the VE initiator to select appropriate partners. General criteria such as price, lead time, quality, etc. are the major concerns for most VE initiators. However, in today's environmentally conscious society, environmental issues such as enterprise green image, product eco-design, etc. are increasingly receiving attention. Thus, it is worth to research on how to select the appropriate collaborative partners to establish an ecological VE. The objective of this paper is to establish a multi-agent system platform for individual companies to form an ecological VE based on ontology theory and intelligent agents. The ontological approaches include shared ontology construction, ontology matching, ontology integration, ontology storage and ontology reasoning. In the generalized case that the VE initiator is a manufacturer and the collaborating partner are suppliers, the multi-agent system comprises three types of intelligent agents, namely, knowledge manager agent (KMrA), manufacturer agent (MA) and supplier agent (SA). MA and SA represent the capabilities and interests of the VE initiator and the VE partners, respectively. KMrA is in charge of functioning sub-tasks of the ontological approach. To select partners for the ecological VE, the VE initiator will also consider the environmental criteria, in addition to the general supplier selection criteria such as price, quantity, quality and lead time. The environmental criteria may include factors such as environmental management, green image, green product and pollution control. The complete set of selection criteria, including the environmental criteria, are categorised into quantitative or qualitative criteria. The formation of ecological VE is then divided into two stages, that is, candidate supplier selection based on qualitative criteria, and ultimate supplier selection based on quantitative criteria. A simplified example is introduced to illustrate and justify the proposed ontological approaches and intelligent agent platform. © 2011 Elsevier Ltd. All rights reserved.


Zou D.,Northeastern University China | Gao L.,Northeastern University China | Li S.,University of South Australia | Wu J.,Northeastern University China
Expert Systems with Applications | Year: 2011

This paper proposes an effective global harmony search algorithm (EGHS) to solve two kinds of reliability problems: the complex (bridge) system optimization problem and the reliability-redundancy optimization problem of the overspeed protection system for a gas turbine. In general, the two problems are formulated as mixed-integer nonlinear programming problems with several constraints. The EGHS combines harmony search algorithm (HS) with concepts from the swarm intelligence of particle swarm optimization algorithm (PSO) to solve optimization problems. The proposed algorithm has been applied to two typical problems with results better than previously reported. The results have demonstrated that the EGHS has strong convergence and capacity of space exploration on solving reliability optimization problems. © 2010 Elsevier Ltd. All rights reserved.


Shi S.,Northeastern University China | Zhang Q.,Northeastern University China | Yuan Z.,Shenyang University | Liu W.,Curtin University Australia
IET Control Theory and Applications | Year: 2011

In this study, the authors investigate the control problem of switched singular systems aiming to compress their inconsistent state jumps when switch occurs between two different singular subsystems. The proposed hybrid impulsive controller consists of a feedback controller and an impulsive controller. With introduction of the impulsive controller, the state at each switching instant for the closed-loop system can be changed. Based on the given controller structure, some sufficient conditions are derived under which the closed-loop system is admissible (regular, impulse free and stable) and such a controller has the capability of eliminating or minimising the instantaneous state jumps at switching instants. The validity and advantage of the proposed hybrid impulsive controller are illustrated using two examples. © 2011 The Institution of Engineering and Technology.


An X.Z.,Northeastern University China | Yu A.B.,University of New South Wales
Powder Technology | Year: 2013

Ordered packing of hard spheres, namely {111}- and {100}-oriented FCC, is numerically generated by means of Discrete Element Method (DEM). The probability density distribution P(F) and transmission of interparticle forces in such a packing is analyzed in detail. It is shown that P(F) can be described by a symmetric distribution irrespective of the orientation, consistent with the literature findings. However, different orientations lead to different force transmissions because of the effect of gravity and stability requirement. In the {111}-oriented FCC, forces transmit both horizontally (in-plane) and vertically (inter-plane), while only vertical inter-plane forces are observed in the {100}-oriented FCC. The analysis on the two resulting sandpiles shows that a force peak exists at the position right under the sandpile apex. © 2013 Elsevier B.V.


Jin X.-Z.,Shenyang University | Yang G.-H.,Northeastern University China
Journal of the Franklin Institute | Year: 2013

The robust fault-tolerant control (FTC) problem against network faults and time-delays of a class of nonlinearly coupled chaotic systems is addressed in this paper. Two kinds of faults on networks, that is, network deterioration and signal attenuations, and a perturbation caused by general nonlinear couplings and time-varying bounded delays are considered in the FTC chaotic system designs. A sliding mode control strategy is proposed, guaranteeing the compensation of the faulted and perturbed couplings by means of adaptive estimations of unknown controller parameters. It is shown that, through Lyapunov stability theory, the proposed adaptive sliding mode controllers are successful in ensuring the achievement of asymptotic synchronization of chaotic systems even in the case of faulted and perturbed couplings. The proposed controller is tested by simulation on a unified chaotic system. © 2013 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.


Shi W.,Northeastern University China | Gong P.,Beijing Institute of Technology
International Journal of Distributed Sensor Networks | Year: 2013

User authentication in wireless sensor networks (WSNs) is a critical security issue due to their unattended and hostile deployment in the field. Since sensor nodes are equipped with limited computing power, storage, and communication modules, authenticating remote users in such resource-constrained environments is a paramount security concern. To overcome the weaknesses of Yeh et al.'s protocol, we proposed a new authentication protocol for wireless sensor networks using elliptic curves cryptography. The comparisons show that our protocol is more suitable for WSNs. © 2013 Wenbo Shi and Peng Gong.


Cui W.F.,Northeastern University China | Jin L.,Northeastern University China | Zhou L.,Institute of Northwestern Nonferrous Metal Research
Materials Science and Engineering C | Year: 2013

A porous bioactive titania coating on biomedical β titanium alloy was prepared by pre-anodization followed by micro arc oxidation technology. The effects of pre-anodization on the phase constituent, morphology and electrochemical corrosion behavior of the microarc oxidation coating were investigated. The results show that pre-anodization has less influence on the phase constituent and the surface morphology of the microarc oxidation coating, but improves the inner layer density of the microarc oxidation coating. The decrease of plasma discharge strength due to the presence of the pre-anodized oxide film contributes to the formation of the compact inner layer. The pre-anodized microarc oxidation coating effectively inhibits the penetration of the electrolyte in 0.9% NaCl solution and thus increases the corrosion resistance of the coated titanium alloy in physiological solution. © 2013 Elsevier B.V.


Zhang B.,University of Texas at Austin | Zhang B.,Northeastern University China | Lee W.H.,University of Texas at Austin | Piner R.,University of Texas at Austin | And 5 more authors.
ACS Nano | Year: 2012

A two-step CVD route with toluene as the carbon precursor was used to grow continuous large-area monolayer graphene films on a very flat, electropolished Cu foil surface at 600 °C, lower than any temperature reported to date for growing continuous monolayer graphene. Graphene coverage is higher on the surface of electropolished Cu foil than that on the unelectropolished one under the same growth conditions. The measured hole and electron mobilities of the monolayer graphene grown at 600 °C were 811 and 190 cm 2/ (V·s), respectively, and the shift of the Dirac point was 18 V. The asymmetry in carrier mobilities can be attributed to extrinsic doping during the growth or transfer. The optical transmittance of graphene at 550 nm was 97.33%, confirming it was a monolayer, and the sheet resistance was ∼8.02 × 10 3 δ/□. © 2012 American Chemical Society.


Li D.,Beijing Institute of Technology | Wang Y.,Beijing Institute of Technology | Xiao G.,Beijing Institute of Technology | Tang J.,Northeastern University China
Computers and Operations Research | Year: 2013

Aiming at the problem of scheduling with flexible processing routes and exceptional parts that need to visit machines located in multiple job shop cells, a pheromone based approach (PBA) using multi-agent is presented in this paper, in which various types of pheromone inspired by ant colony optimization (ACO) are adopted as the basis of negotiation among agents. By removing redundant routes and constructing coalition agents, communication cost and negotiation complexity are reduced, and more importantly, the global performance of scheduling is improved. The performance of the PBA is evaluated via experiments with respect to the mean flow time, maximum completion time, mean tardiness, ratio of tardy parts, and ratio of intercell moves. Computational results show that compared with various heuristics, the PBA has significant advantages with respect to the performance measures considered in this paper.


Jin X.-Z.,Northeastern University China | Jin X.-Z.,Shenyang University | Yang G.-H.,Northeastern University China
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011

This paper is concerned with the robust synchronization problem for a class of uncertain dynamical complex networks against network deterioration. As deteriorated networks and uncertainties may lead to performance degradation or even instability of the whole network, an adaptive approach is proposed to adjust unknown coupling factors for the deteriorated network compensations, as well as to estimate controller parameters to compensate the effects of uncertainty on-line without assuming symmetry or irreducibility of networks. Through Lyapunov functions and adaptive schemes, pinning controllers are constructed to ensure that the synchronization errors of the networks can be reduced as small as desired in the presence of the network deterioration and uncertainty. Simulation results are given to verify the effectiveness of the proposed method. © 2006 IEEE.


Zhang H.,Northeastern University China | Cui L.,Shenyang Normal University | Luo Y.,Northeastern University China
IEEE Transactions on Cybernetics | Year: 2013

In this paper, a near-optimal control scheme is proposed to solve the nonzero-sum differential games of continuoustime nonlinear systems. The single-network adaptive dynamic programming (ADP) is utilized to obtain the optimal control policies which make the cost functions reach the Nash equilibrium of nonzero-sum differential games, where only one critic network is used for each player instead of the action-critic dual network used in a typical ADP architecture. Furthermore, the novel weight tuning laws for critic neural networks are proposed, which not only ensure the Nash equilibrium to be reached but also guarantee the system to be stable. No initial stabilizing control policy is required for each player. Moreover, Lyapunov theory is utilized to demonstrate the uniform ultimate boundedness of the closed-loop system. Finally, a simulation example is given to verify the effectiveness of the proposed near-optimal control scheme. © 2012 IEEE.


Lian J.,Dalian University of Technology | Zhao J.,Northeastern University China
International Journal of Control, Automation and Systems | Year: 2010

This paper investigates the robust sliding mode control (SMC) problem for a class of uncertain switched systems with time-varying delay. The sliding surface is constructed such that the sliding motion is completely invariant to all admissible uncertainties. For the case of the known delay-derivative upper bound, by using the multiple Lyapunov functions method, the Hysteresis switching law dependent on the state and the previous value of switching signal are designed to stabilize the sliding motion and avoid the chattering. Variable structure controllers are developed to drive the state of switched systems to reach the sliding surface in finite time and remain on it thereafter. For the case of the unknown delay-derivative upper bound, based on the single Lyapunov function method, the conditions of stabilization are obtained. Finally, a numerical example is given to illustrate the effectiveness of the proposed methods. © ICROS, KIEE and Springer 2010.


Wang Y.-E.,Northeastern University China | Sun X.-M.,Dalian University of Technology | Zhao J.,Northeastern University China
Journal of the Franklin Institute | Year: 2012

In this paper, we study the issue of asynchronous H∞ control for a class of switched delay systems. The switching signal of the switched controller involves time delay, which results in the asynchronous switching between the candidate controllers and the systems. By combining the piecewise Lyapunov-Krasovskii functional method with the merging switching signal technique, sufficient conditions of the existence of admissible H∞ state-feedback controllers are developed for the switched delay system under an average dwell time scheme. These conditions imply the relationship among the upper bound of the state delay, the switching delay and the average dwell time. Finally, a numerical example is given to illustrate the effectiveness of the proposed theory. © 2012 The Franklin Institute.


Wang Y.,Northeastern University China | Zhang H.,Northeastern University China | Wang X.,Dalian University of Technology | Yang D.,Northeastern University China
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2010

This paper is concerned with the networked synchronization control problem of coupled dynamic networks (CDNs) with time-varying delay. First, both the data packet dropouts and network-induced delays are taken into account in the synchronization controller design. A Markovian jump process is induced to describe the packet dropouts. The network-induced delays are interval time varying and depend on the Markovian jump modes. A new closed-loop coupled dynamic error system (CDES) with Markovian jump parameters and interval time-varying delays is constructed. Second, using the Kronecker product technique and the stochastic Lyapunov method, a delay-dependent sufficient criterion of stochastic stability is obtained for the closed-loop CDES, which also guarantees that the CDNs are stochastically synchronized. Finally, a simulation example is given to demonstrate the effectiveness of the proposed result. © 2010 IEEE.


Wang W.-Q.,University of Electronic Science and Technology of China | Jiang D.,Northeastern University China
IEEE Sensors Journal | Year: 2014

Due to extreme conditions, the near-space region is vastly underused and can be utilized for various scientific uses. The unconstrained orbital mechanism and low fuel consumption advantages for using synthetic aperture radar over the satellites and airplanes navigation systems make these conditions superior for a wide range of services, monitoring, earth observation, and sensing applications. The augmented integration within the existing global navigation system can help in measuring the direction-of-arrival, as well as collecting and distributing accurate location information. For wireless sensing applications, it can enable a new range of opportunities, a wide range of smart sensor applications as experimental platforms for deployment of new technologies. Here, we also examine the implementation of near-space platform (NSP) coverage and associated technologies. Then, a brief integration of communication and navigation services using NSP from a top-level system description of how to relay, associated complementary systems, including radar sensor systems, satellite systems, and terrestrial networks can be used. © 2001-2012 IEEE.


Cui M.,Dalian University of Technology | Gao X.,Dalian University of Technology | Chen H.,Northeastern University China
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2011

Non-gray radiative properties of an absorbing, emitting, non-gray participating medium significantly increase the difficulty of solving the radiative transfer equation. This paper presents a new inverse approach for the equivalent gray radiative property of a non-gray medium. In this approach, the unknown equivalent gray radiative properties are treated as the optimization variables, and the errors to be minimized are the differences between the calculated temperatures and the measured ones. The measured data are simulated by solving the direct problem, in which a modified zonal method together with the Edwards exponential wide-band model is employed. In the inverse problem, the sensitivity coefficients are first calculated by the complex-variable-differentiation method, and then the least-square method and the Newton-Raphson iterative method are employed to minimize the target function. The effectiveness and efficiency of the inverse problem are demonstrated in an example, and another case is given to show the accuracy and potential of the proposed algorithm. The effects of the measurement error and the number of measurement points on the accuracy of the inverse analysis are also investigated in detail. © 2011 Elsevier Ltd.


Wang Y.-E.,Northeastern University China | Sun X.-M.,Dalian University of Technology | Wang Z.,University of Alberta | Zhao J.,Northeastern University China
Automatica | Year: 2014

This paper studies the stability issue for switched nonlinear systems with input delay and disturbance. It is assumed that for the nominal system an exponential stabilizing controller is predesigned such that the switched system is stable under a certain switching signal, and a piecewise Lyapunov function for the corresponding closed-loop system is known. However, in the presence of input delay and disturbance, the system may be unstable under the same switching signal. For this case, a new Lyapunov-Krasovskii functional is firstly constructed based on the known Lyapunov function. Then, by employing this new functional, a new switching signal satisfying the new average dwell time conditions is constructed to guarantee the input-to-state stability of the system under a certain delay bound. The bound on the average dwell time is closely related to the bound on the input delay. Finally, numerical examples are given to illustrate the effectiveness of the proposed theory. © 2014 Elsevier Ltd. All rights reserved.


Wang Y.-E.,Northeastern University China | Wang R.,Dalian University of Technology | Zhao J.,Northeastern University China
IET Control Theory and Applications | Year: 2013

This study addresses the input-to-state stability (ISS) of non-linear impulsive and switched delay systems. Based on the piecewise Lyapunov-Krasovskii functional method, the authors show that when only some of the constituent subsystems are ISS, the ISS property still can be retained for the non-linear impulsive and switched delay system, if the dwell time of the ISS subsystems satisfies a lower bound condition and the activation time of the non-ISS subsystems satisfies an upper bound condition, respectively. In common parlance, some of the intervals must be overly long, whereas the others must be short enough between impulses. Compared with existing results on related problems, the theory can be applied to a larger class of systems. The proposed approach also enables us to give the analysis of systems involving actuator failure, controller failure or temporary uncertain switching signal. As an example, the authors employ the method to analyse the problem of reliable control for a mechanical rotational cutting process. © The Institution of Engineering and Technology 2013.


Lian J.,Dalian University of Technology | Zhao J.,Northeastern University China
Circuits, Systems, and Signal Processing | Year: 2010

This paper investigates the robust H∞ control problem for a class of uncertain switched delay systems with parameter uncertainties, unknown nonlinear perturbations, and external disturbance. Based on the multiple Lyapunov functions method, a sufficient condition for the solvability of the robust H∞ control problem is derived by employing a hysteresis switching law and variable structure controllers.When the upper bounds of the nonlinear perturbations are unknown, an adaptive variable structure control strategy is developed. The use of the adaptive technique is to adapt the unknown upper bounds of the nonlinear disturbances so that the objective of asymptotic stabilization with an H∞-norm bound is achieved under the hysteresis switching law. A numerical example illustrates the effectiveness of the proposed design methods. © Springer Science+Business Media, LLC 2010.


Ma H.,Northeastern University China | Shi C.,Nagoya University | Han Q.,Dalian University of Technology | Wen B.,Northeastern University China
Mechanical Systems and Signal Processing | Year: 2013

In this paper, fault characteristics of a single span rotor system with two discs are investigated when the rubbing between a disc and an elastic rod (a fixed limiter) occurs. First, a finite element (FE) model of the rotor system is developed, a point-point contact model is established to simulate the rotor-stator rubbing by simplifying the disc and the rod as two contact points, and then the two models are coupled by contact force. In addition, the augmented Lagrangian method is applied to deal with contact constraint conditions and the coulomb friction model is used to simulate rotor-stator frictional characteristics. The vibration features of the rotor system with rubbing are analyzed with respect to the effects of the gaps between the disc and the rod, the contact stiffnesses under three typical cases with different rotating speeds. The simulation results show that different rotor motions appear, such as period-one motion (P1), P2 and P3 with the increasing rotating speeds, which are in agreement with the experimental measurements. Besides, the gap between the disc and the rod as well as the contact stiffness has a main influence on the vibration intensity and collision rebound forms. © 2012 Elsevier Ltd.


Chen S.-S.,Northeastern University China | Li B.-W.,Dalian University of Technology
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2014

A collocation spectral domain decomposition method (CSDDM) based on the influence matrix technique is developed to solve radiative transfer problems within a participating medium of 2D partitioned domains. In this numerical approach, the spatial domains of interest are decomposed into rectangular sub-domains. The radiative transfer equation (RTE) in each sub-domain is angularly discretized by the discrete ordinates method (DOM) with the SRAPN quadrature scheme and then is solved by the CSDDM directly. Three test geometries that include square enclosure and two enclosures with one baffle and one centered obstruction are used to validate the accuracy of the developed method and their numerical results are compared to the data obtained by other researchers. These comparisons indicate that the CSDDM has a good accuracy for all solutions. Therefore this method can be considered as a useful approach for the solution of radiative heat transfer problems in 2D partitioned domains. © 2014 Elsevier Ltd.


Yang C.,China University of Mining and Technology | Yang C.,Northeastern University China | Sun J.,University of Michigan | Ma X.,China University of Mining and Technology
Automatica | Year: 2013

This paper considers the stabilization bound problem for singularly perturbed systems (SPSs) subject to actuator saturation. A state feedback stabilization controller design method is proposed and a basin of attraction depending on the singular perturbation parameter is constructed, which facilitates the formulation of the convex optimization problem for maximizing the basin of attraction of SPSs. Finally, examples are given to show the advantages and effectiveness of the obtained results. © 2012 Elsevier Ltd. All rights reserved.


Wei Y.,Northeastern University China | Shen G.,Neusoft Medical Systems Co. | Li J.-J.,Northeastern University China
Journal of Digital Imaging | Year: 2013

Considering that the traditional lung segmentation algorithms are not adaptive for the situations that most of the juxtapleural nodules, which are excluded as fat, and lung are not segmented perfectly. In this paper, several methods are comprehensively utilized including optimal iterative threshold, three-dimensional connectivity labeling, three-dimensional region growing for the initial segmentation of the lung parenchyma, based on improved chain code, and Bresenham algorithms to repair the lung parenchyma. The paper thus proposes a fully automatic method for lung parenchyma segmentation and repairing. Ninety-seven lung nodule thoracic computed tomography scans and 25 juxtapleural nodule scans are used to test the proposed method and compare with the most-cited rolling-ball method. Experimental results show that the algorithm can segment lung parenchyma region automatically and accurately. The sensitivity of juxtapleural nodule inclusion is 100 %, the segmentation accuracy of juxtapleural nodule regions is 98.6 %, segmentation accuracy of lung parenchyma is more than 95.2 %, and the average segmentation time is 0.67 s/frame. The algorithm can achieve good results for lung parenchyma segmentation and repairing in various cases that nodules/tumors adhere to lung wall. © 2012 Society for Imaging Informatics in Medicine.


Cui M.,Dalian University of Technology | Gao X.,Dalian University of Technology | Chen H.,Northeastern University China
International Journal of Thermal Sciences | Year: 2011

This paper presents a new inverse radiation analysis approach in an absorbing, emitting and non-gray participating medium. The inverted unknowns are treated as the optimization variables, and the errors to be minimized are the differences between the calculated temperatures and the experimental ones. The measured temperatures are simulated by the solution of the direct problem, in which a modified zonal method is employed to solve the radiative transfer equation, and the Edwards exponential wide-band model together with the Leckner series is adopted to obtain the radiative property of the non-gray medium. The contribution is to introduce the complex-variable-differentiation method into inverse radiation problems for calculating sensitivity coefficients. The least-square method is employed in the inverse problem. The effectiveness and efficiency of the inverse problem are demonstrated by an example. In addition, the effects of the measurement error and the thermal operating parameters on the inverse analysis are investigated.© 2011 Elsevier Masson SAS. All rights reserved.


Wang J.-W.,Northeastern University China | Wang J.-W.,Dalian University of Technology | Rong L.-L.,Dalian University of Technology
Safety Science | Year: 2011

Power systems are the basic support of modern infrastructures and protecting them from random failures or intentional attacks is an active topic of research in safety science. This paper is motivated by the following two related problems about cascading failures on power grids: efficient edge attack strategies and lower cost protections on edges. Applying the recent cascading model by adopting a local load redistribution rule, where the initial load of an edge ij is (kikj)θ with ki and kj being the degrees of the nodes connected by the edge, we investigate the performance of the power grid of the western United States subject to three intentional attacks. Simulation results show that the effects of different attacks for the network robustness against cascading failures have close relations with the tunable parameter θ. Particularly, the attack on the edges with the lower load in the case of θ<1.4 can result in larger cascading failures than the one on the edges with the higher load. In addition, compared with the other two attacks, a new attack, i.e., removing the edges with the smallest proportion between the total capacities of the neighboring edges of and the capacity of the attacked edge, usually are prone to trigger cascading failures over the US power grid. Our findings will be not only helpful to protect the key edges selected effectively to avoid cascading-failure-induced disasters, but also useful in the design of high-robustness and low-cost infrastructure networks. © 2010 Elsevier Ltd.


Fan Z.-P.,Northeastern University China | Suo W.-L.,Northeastern University China | Suo W.-L.,CAS Institute of Policy and Management | Feng B.,South China University of Technology
Expert Systems with Applications | Year: 2012

Risk factor identification of IT outsourcing is significant to capture the source of IT outsourcing risk. Risk factors of IT outsourcing are often interdependent, and consequently the interrelationships among factors affect risk factor identification, whereas this fact is neglected in the existing studies. The purpose of this paper is to investigate a method for identifying risk factors of IT outsourcing, in which the interrelationships among risk factors are considered. Firstly, the risk factors of IT outsourcing are figured out through literature review and expert interview. Then, the interrelationships among risk factors and relative analysis are given. Furthermore, based on the 2-tuple fuzzy linguistic representation model and the classical Decision Making Trial and Evaluation Laboratory (DEMATEL) method, an extended DEMATEL method is developed to identify the importance together with the classification of risk factors. Finally, the potential of the proposed method is shown through an illustrative example of a Chinese resource company. © 2011 Elsevier Ltd. All rights reserved.


Liu L.,Northeastern University China | Yang S.,Brunel University | Wang D.,Northeastern University China
Information Sciences | Year: 2012

Multimodal optimization problems pose a great challenge of locating multiple optima simultaneously in the search space to the particle swarm optimization (PSO) community. In this paper, the motion principle of particles in PSO is extended by using the near-neighbor effect in mechanical theory, which is a universal phenomenon in nature and society. In the proposed near-neighbor effect based force-imitated PSO (NN-FPSO) algorithm, each particle explores the promising regions where it resides under the composite forces produced by the "near-neighbor attractor" and "near-neighbor repeller", which are selected from the set of memorized personal best positions and the current swarm based on the principles of "superior-and-nearer" and "inferior-and-nearer", respectively. These two forces pull and push a particle to search for the nearby optimum. Hence, particles can simultaneously locate multiple optima quickly and precisely. Experiments are carried out to investigate the performance of NN-FPSO in comparison with a number of state-of-the-art PSO algorithms for locating multiple optima over a series of multimodal benchmark test functions. The experimental results indicate that the proposed NN-FPSO algorithm can efficiently locate multiple optima in multimodal fitness landscapes. © 2011 Elsevier Inc. All rights reserved.


Sun L.,Northeastern University China | Gao F.,Guangxi University | Huang Q.,Guangxi University
Journal of Alloys and Compounds | Year: 2014

The upconversion (UC) photoluminescence and ferroelectric properties of Er3+-Tm3+-Yb3+ tri-codoped bismuth titanate (BETYT) thin films were studied. The thin films were prepared by chemical solution deposition method. There are four emission bands in the visible UC luminescence spectra excited by 980 nm at room temperature. The 478 nm blue emission band corresponds to 1G4 → 3H 6 transition of Tm3+, and the 527 nm, 548 nm green emission bands correspond to 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions of Er3+, and the 657 nm red emission band corresponds to 4F9/2 → 4I15/2 transition of Er3+ and 1G4 → 3F4 transition of Tm 3+. The fluorescent color can be tuned by adjusting Er3+, Tm3+ and Yb3+ concentrations and the optimal color coordinate in these films is (0.31, 0.34), very close to the standard white-light coordinate of (0.33, 0.33) when pumped under power intensity about 2.8 W/cm2. The UC emission mechanism was discussed and there exist significant energy transfers from Er3+ to Tm3+, which will affect the relative intensity of blue, green and red emissions and their quenching concentrations. The remanent polarization (2Pr) value of BEr 0.0085TYT thin film prepared on Pt/Ti/SiO2/Si substrate is 27.8 μC/cm2. The combination of UC photoluminescence and ferroelectric properties in BETYT thin films would open the possibility of inventing novel multifunctional optoelectronic integration devices. © 2013 Elsevier B.V. All rights reserved.


Zhou J.,IRIS - International Research Institute of Stavanger | Wen C.,Nanyang Technological University | Yang G.,Northeastern University China
IEEE Transactions on Automatic Control | Year: 2014

In this paper, we study a general class of strict feedback nonlinear systems, where the input signal takes quantized values. We consider a stabilization problem for nonlinear uncertain systems via adaptive backstepping approach. The control design is achieved by introducing a hysteretic quantizer to avoid chattering and using backstepping technique. A guideline is derived to select the parameters of the quantizer. The designed controller together with the quantizer ensures the stability of the closed-loop system in the sense of signal boundedness. © 1963-2012 IEEE.


Yu F.,Shenyang Aerospace University | Zhang J.-F.,Northeastern University China
Communications in Theoretical Physics | Year: 2013

We apply the statefinder diagnostic to the extended holographic Ricci dark energy (ERDE) model without and with interaction to study their behaviors. We plot the trajectories of various parameters for different cases. It is shown that the non-interacting model does not reach the LCDM point {1, 0} and the interacting one is favored, because the interaction makes the evolution of the statefinder pair {r, s} quite different. © 2013 Chinese Physical Society and IOP Publishing Ltd.


Zhao S.,Northeastern University China | Zhao S.,University of Nebraska - Lincoln | Yang W.,University of Nebraska - Lincoln | Lai R.Y.,University of Nebraska - Lincoln
Biosensors and Bioelectronics | Year: 2011

We herein report a folding-based electrochemical DNA aptasensor for the detection of vascular endothelial growth factor (VEGF) directly in complex biological samples, including blood serum and whole blood. The electrochemical signal generation is coupled to a large, target-induced conformational change in a methylene blue-modified and surface immobilized anti-VEGF aptamer. The sensor is sensitive, selective and essentially reagentless: we can readily detect VEGF down to 5. pM (190. pg/mL) directly in 50% blood serum. Similar to other aptasensors of this class, the VEGF sensor is also regenerable and reusable. In addition, the sensor performs comparably well even when fabricated on a gold-plated screen-printed carbon electrode and can potentially be implemented as a cost-effective, single-use biosensor for diseases diagnosis and therapy monitoring. The exceptional sensitivity, selectivity, and reusability of this electrochemical aptasensor platform suggest it may be a promising strategy for a wide variety of sensing applications. © 2010 Elsevier B.V.


Kong W.,Northeastern University China | Chai T.,Northeastern University China | Yang S.,Brunel University | Ding J.,Northeastern University China
Applied Soft Computing Journal | Year: 2013

The supply trajectory of electric power for submerged arc magnesia furnace determines the yields and grade of magnesia grain during the manufacture process. As the two production targets (i.e., the yields and the grade of magnesia grain) are conflicting and the process is subject to changing conditions, the supply of electric power needs to be dynamically optimized to track the moving Pareto optimal set with time. A hybrid evolutionary multiobjective optimization strategy is proposed to address the dynamic multiobjective optimization problem. The hybrid strategy is based on two techniques. The first one uses case-based reasoning to immediately generate good solutions to adjust the power supply once the environment changes, and then apply a multiobjective evolutionary algorithm to accurately solve the problem. The second one is to learn the case solutions to guide and promote the search of the evolutionary algorithm, and the best solutions found by the evolutionary algorithm can be used to update the case library to improve the accuracy of case-based reasoning in the following process. Due to the effectiveness of mutual promotion, the hybrid strategy can continuously adapt and search in dynamic environments. Two prominent multiobjective evolutionary algorithms are integrated into the hybrid strategy to solve the dynamic multiobjective power supply optimization problem. The results from a series of experiments show that the proposed hybrid algorithms perform better than their component multiobjective evolutionary algorithms for the tested problems. © 2012 Elsevier B.V. All rights reserved.


Yang Y.,Northeastern University China | Chen J.,Hainan Litree Purifying Technology Co.
Advanced Materials Research | Year: 2013

Advanced treatment of drinking water was performed by ultrafiltration process (UF) in this study. Experimental results showed that UF is a perfect physical sieving barrier to remove turbidity, algae and bacteria from water, which is far superior to conventional water treatment processes. But the ultrafiltration membrane is not very effective for the removal of dissolved organic matter because of the large molecular weight cut-off. And the backwashing per 30min can totally renew the ultrafiltration membrane. © (2013) Trans Tech Publications, Switzerland.


Wang H.,Northeastern University China | Wang H.,Pusan National University | Moon I.,Pusan National University | Yang S.,Northeastern University China | And 2 more authors.
Information Sciences | Year: 2012

Recently, multimodal optimization problems (MMOPs) have gained a lot of attention from the evolutionary algorithm (EA) community since many real-world applications are MMOPs and may require EAs to present multiple optimal solutions. In this paper, a memetic algorithm that hybridizes particle swarm optimization (PSO) with a local search (LS) technique, called memetic PSO (MPSO), is proposed for locating multiple global and local optimal solutions in the fitness landscape of MMOPs. Within the framework of the proposed MPSO algorithm, a local PSO model, where the particles adaptively form different species based on their indices in the population to search for different sub-regions in the fitness landscape in parallel, is used for globally rough exploration, and an adaptive LS method, which employs two different LS operators in a cooperative way, is proposed for locally refining exploitation. In addition, a triggered re-initialization scheme, where a species is re-initialized once converged, is introduced into the MPSO algorithm in order to enhance its performance of solving MMOPs. Based on a set of benchmark functions, experiments are carried out to investigate the performance of the MPSO algorithm in comparison with some EAs taken from the literature. The experimental results show the efficiency of the MPSO algorithm for solving MMOPs. © 2012 Elsevier Inc. All rights reserved.


Grant
Agency: Department of Defense | Branch: Defense Advanced Research Projects Agency | Program: STTR | Phase: Phase II | Award Amount: 978.26K | Year: 2014

The objective of this project is to evolve the RF device ontology developed in Phase I, design and implement a run time prototype system, develop a test environment and perform an evaluation of the approach developed in Phase I. Based upon the findings and success of Phase I, we propose to continue the work on the Dev2WALDO ontology, augment it with necessary concepts, design and develop a prototype of DeVISor and carry out evaluation and assessment of the ontology expressiveness in describing capabilities of RF devices. DeVISor will interact with applications that require knowledge of the available RF devices on the one side and RF devices themselves on the other side. DeVISor will be connected to the network via the APIs of the network operating system (e.g., WALDO). DeVISor will answer applications' queries about the availability, capabilities and status of the particular devices.


Grant
Agency: Department of Defense | Branch: Defense Advanced Research Projects Agency | Program: STTR | Phase: Phase I | Award Amount: 95.02K | Year: 2013

VIStology, Northeastern University and BBN are proposing a standards-based solution to seamless insertion of new RF devices and capabilities into multifunction Electronic Warfare (EW)/Intelligence, Surveillance and Reconnaissance (ISR) networks without re


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2012

An intelligence analyst"s job is to monitor a stream of incoming reports and sensor data for information relevant to a situation, detect the salient information, answer the commander"s priority intelligence requirements (PIRs) and distill the salient information into a concise estimate of what is currently going on, what is most likely to happen, and what is the most dangerous course of events that could happen next. The question we will be pursuing is the extent to which the detection of salient information can be captured algorithmically, so that computerized systems can augment and assist the analyst in capturing salient information. VIStology and Northeastern University"s goal in this project is to examine the context, activity and artifacts involved in the intelligence analyst"s task and to explore how they might be used to model the excitation of a conceptual network that can be used to derive a measure of information salience for incoming reports. We will then validate this model experimentally.


Grant
Agency: Department of Defense | Branch: Missile Defense Agency | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2012

System requirements elicitation is a time consuming process with an extremely high penalty for errors. Mistakes made in the requirements phase will cost 50 times more to fix while they are uncovered in the production phase as compared to fixing them in the requirements phase. VIStology and Northeastern University are proposing to develop an approach for supporting the requirements elicitation phase with computer tools. Our approach will include tool support for analyzing requirements represented in text, extracting information from text and representing it in a formal language with computer processable semantics, analyzing the formal representation of specifications, storing the formal representations for future extraction and comparison, and guiding the systems engineer who will be in the loop of requirements formalization and analysis. We will provide an initial prototype of the system that will proof the feasibility of the proposed approach. Moreover, we will provide an assessment of the usability and the efficiency of the approach via experimentation with Northeastern graduate students.


Zhang H.,Northeastern University China | Xie X.,Northeastern University China | Tong S.,Liaoning University of Technology
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

This paper proposes a novel H∞ filtering technique for a class of discrete-time fuzzy systems. First, a novel kind of fuzzy H ∞ filter, which is homogenous polynomially parameter dependent on membership functions with an arbitrary degree, is developed to guarantee the asymptotic stability and a prescribed H∞ performance of the filtering error system. Second, relaxed conditions for H∞ performance analysis are proposed by using a new fuzzy Lyapunov function and the Finsler lemma with homogenous polynomial matrix Lagrange multipliers. Then, based on a new kind of slack variable technique, relaxed linear matrix inequality-based H∞ filtering conditions are proposed. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed approach. © 2011 IEEE.


Guo D.,National University of Defense Technology | Wu J.,Temple University | Chen H.,National University of Defense Technology | Yuan Y.,Northeastern University China | Luo X.,National University of Defense Technology
IEEE Transactions on Knowledge and Data Engineering | Year: 2010

A Bloom filter is an effective, space-efficient data structure for concisely representing a set, and supporting approximate membership queries. Traditionally, the Bloom filter and its variants just focus on how to represent a static set and decrease the false positive probability to a sufficiently low level. By investigating mainstream applications based on the Bloom filter, we reveal that dynamic data sets are more common and important than static sets. However, existing variants of the Bloom filter cannot support dynamic data sets well. To address this issue, we propose dynamic Bloom filters to represent dynamic sets, as well as static sets and design necessary item insertion, membership query, item deletion, and filter union algorithms. The dynamic Bloom filter can control the false positive probability at a low level by expanding its capacity as the set cardinality increases. Through comprehensive mathematical analysis, we show that the dynamic Bloom filter uses less expected memory than the Bloom filter when representing dynamic sets with an upper bound on set cardinality, and also that the dynamic Bloom filter is more stable than the Bloom filter due to infrequent reconstruction when addressing dynamic sets without an upper bound on set cardinality. Moreover, the analysis results hold in stand-alone applications, as well as distributed applications. © 2006 IEEE.


Tong S.,Liaoning University of Technology | He X.,Liaoning University of Technology | Li Y.,Liaoning University of Technology | Zhang H.,Northeastern University China
Fuzzy Sets and Systems | Year: 2010

This paper proposes an adaptive fuzzy robust control method for SISO nonlinear systems with nonlinear uncertainties, unmodeled dynamics and dynamic disturbances. Fuzzy logic systems are used to approximate the nonlinear uncertainties, with no prior knowledge of their bounds. Based on the modeled nonlinear uncertainties using fuzzy logic systems, a stable adaptive fuzzy backstepping robust controller is proposed by combining the backstepping technique with the small-gain approach. It is mathematically proven that the proposed adaptive fuzzy control approach can guarantee that the closed-loop system is uniformly bounded. The effectiveness of the proposed approach is illustrated via two examples. © 2009 Elsevier B.V. All rights reserved.


Zhai Y.,Fudan University | Dou Y.,Northeastern University China | Liu X.,Northeastern University China | Park S.S.,Pusan National University | And 2 more authors.
Carbon | Year: 2011

Ordered mesoporous carbon/nanoparticle nickel composites have been synthesized via multi-component co-assembly strategy associated with a direct carbonization process from resol, tetraethyl orthosilicate, Ni(NO 3)2·6H2O and triblock copolymer F127 and subsequent silicates removal with NaOH solution. The incorporation of rigid silicates in the pore walls can reduce framework shrinkage significantly during the pyrolysis process, creating large mesopores. Moreover, plenty of complementary small pores caused by silica removal are observed in the carbon pore walls, which contribute to the large surface area. The mesoporous carbon/nanoparticle nickel composites with a low Ni content (1.7 wt%) possess ordered two-dimensional hexagonal structure, large mesopores (6.8 nm), high surface area (1580 m2 g-1) and large pore volume (1.42 cm3 g-1). Magnetic Ni nanocrystals with particle size of ∼16.0 nm are confined in the matrix of carbon frameworks. With increase of Ni content, the surface area and pore volume of the composites decrease. The particle size of metallic Ni nanocrystals increases up to 20.3 nm, when its content increases to 10 wt%. These carbon/nanoparticle nickel composites with high surface area, large pore size and superparamagnetic property show excellent adsorption properties for bulky dye fuchsin base and an easy separation procedure. © 2010 Elsevier Ltd. All rights reserved.


Zhao L.,Anshan Normal University | Chen L.,Academia Sinica, China | Zhang Q.,Northeastern University China
Mathematical Biosciences | Year: 2012

Using successor functions and Poincaré-Bendixson theorem of impulsive differential equations, the existence of periodical solutions to a predator-prey model with two state impulses is investigated. By stability theorem of periodic solution to impulsive differential equations, the stability conditions of periodic solutions to the system are given. Some simulations are exerted to prove the results. © 2012 Elsevier Inc.


Li M.,Northeastern University China | Wang Z.,Northeastern University China | Reddy R.G.,University of Alabama
Electrochimica Acta | Year: 2014

The electrochemical behavior of Co(II) in urea-choline chloride-CoCl 2 melt was investigated by cyclic voltammetry at 373 K. The results show that the reaction of Co(II) to Co is irreversible and it proceeds via a one-step two electrons transfer process. The diffusion coefficient of Co(II) was estimated to be 1.7 × 10-6 cm2 s-1 at 373 K. Electrodeposition of cobalt was studied at different cathodic potentials (-0.80 to -0.95 V) and at different temperatures (353 to 383 K) in eutectic mixture of choline chloride and urea (1:2 molar ratio). The deposits were characterized using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). SEM images show that uniform, dense, and compact deposits were obtained at -0.80 V within a temperature range of 353 K to 373 K. EDS and XRD analysis confirm that high-purity metallic Co deposits were obtained. © 2014 Elsevier Ltd.


Wang Q.,Northeastern University China | Zhao R.,Laval University | Fafard M.,Laval University | Li B.,Northeastern University China
Applied Thermal Engineering | Year: 2015

A transient three-dimensional (3D) coupled mathematical model is developed in this paper in order to explore the electromagnetic, flow, and temperature fields, as well as the solidification in the electroslag remelting (ESR) process. Maxwell's equations are solved by the Finite Volume Method. The Joule heating and electromagnetic force (EMF), the source terms in the energy and momentum equations, are recalculated during each iteration as function of the phase distribution. The movement of the metal droplets is described by the Volume of Fluid (VOF) approach. Additionally, the solidification of the metal is modeled by an enthalpy-based technique, where the mushy zone is treated as a porous medium with a porosity equal to the liquid fraction. The results show that the electric current tends to go through the metal droplet first. The EMF varies with the falling metal droplet, always blocking the motion of the metal droplet. The zone with the highest temperature appears under the outer radius of the inlet. A larger Joule heating density, as well as a higher average temperature of the molten slag, is obtained when the current increases. Bigger metal droplets form with more heat and momentum, resulting in a deeper liquid metal pool. © 2015 Elsevier Ltd.


Tian Z.-D.,Shenyang University of Technology | Gao X.-W.,Northeastern University China | Shi T.,Liaoning Forestry Vocotion Technical College
Wuli Xuebao/Acta Physica Sinica | Year: 2014

Considering the problem that least squares support vector machine prediction model with single kernel function cannot significantly improve the prediction accuracy of chaotic time series, a combination kernel function least squares support vector machine prediction model is proposed. The model uses a polynomial function and radial basis function to construct the kernel function of least squares support vector machine. An improved genetic algorithm with better convergence speed and precision is proposed for parameter optimization of prediction model. The simulation experimental results of Lorenz, Mackey-Glass, Sunspot-Runoff in the Yellow River and chaotic network traffic time series demonstrate the effectiveness and characteristics of the proposed model. © 2014 Chinese Physical Society


Xu J.,Northeastern University China | Haarberg G.M.,Norwegian University of Science and Technology
High Temperature Materials and Processes | Year: 2013

Silicon is the most common material used in solar cells. High cost of silicon restricts the widely use of PV power. In order to make solar cells more accessible and affordable, it is strongly needed to develop a new and low-cost production process of solar energy silicon (SoG-Si). Electrodeposition of SoG-Si films appears to be a cost saving technique since solidification and sawing steps which contribute significantly to the overall cost of solar cells will be bypassed. Electrodeposition of SoG-Si has been evaluated during the last three decades, and some of them have shown promising results. Thermodynamic and kinetic considerations which relate to the electrodeposition of silicon are discussed, and progresses towards the developments of the electrodeposition of silicon in high temperature molten salts are reviewed in this paper. Copyright © 2013 De Gruyter.


Kobayashi S.,Ashikaga Institute of Technology | Tsurekawa S.,Kumamoto University | Watanabe T.,Northeastern University China | Palumbo G.,Integran Technologies Inc
Scripta Materialia | Year: 2010

Control of brittleness associated with segregation of sulfur to grain boundaries in ultrafine-grained nickel was investigated. The brittleness could be successfully improved by controlling the grain boundary microstructure. The specimens with a higher fraction of special boundaries can have higher fracture toughness even in sulfur-bearing condition. It is evident that grain boundary engineering is applicable to controlling segregation-induced embrittlement in ultrafine-grained materials. © 2009 Acta Materialia Inc.


Tang Y.,Northeastern University China | Mason R.J.,Temple University | Sun P.,Northeastern University China
Habitat International | Year: 2012

Since the onset of rapid economic development and urbanization, China's land resources-rather than capital, technology and human resources-have become the lead limiting factor in constraining economic growth. Coordination of urban and rural construction land (CURCL) can be a very effective means for reducing conflicts between economic development and land protection. This research examines the roles of stakeholders involved in the CURCL process. The reasons why the interests of legitimated stakeholders were encroached upon are analyzed and countermeasures to protect the interests of legitimated stakeholders are proposed. Ambiguously defined property rights for owners of rural construction land, unclear conceptions of the public interest, and overlap of power and interest among multiple levels of authority are the reasons why legitimated stakeholders' interests were encroached upon. Legitimizing construction land ownership clearly, better defining the multiple conceptions of public interest, opening up express channels for expression of the public interest, and clarifying governments' functions in land interest adjustment are the countermeasures to protect the interests of legitimated stakeholders. © 2011 Elsevier Ltd.


Li Y.-X.,Northeastern University China | Li Y.-X.,Liaoning University of Technology | Yang G.-H.,Northeastern University China
IEEE Transactions on Fuzzy Systems | Year: 2016

This paper studies the fuzzy adaptive output feedback fault-tolerant control (FTC) problem for a class of single-input and single-output uncertain nonlinear systems with time-varying nonaffine nonlinear faults in strict-feedback form. In the design procedure, filtered signals are adopted to circumvent algebraic loop problems on implementing the usual controllers. By using fuzzy logic systems to approximate the unknown nonlinearity effects and changes in model dynamics due to faults, a fuzzy state observer is first presented to estimate the unmeasured states. Based on the online estimating information from the adaptive mechanism, an observer-based dynamic output feedback fault-tolerant controller is designed via the backstepping technique. It is shown that the stability and tracking performances of the closed-loop system can be achieved even in the presence of unknown nonlinear faults. In comparison with the existing approaches, the FTC scheme can handle the nonaffine nonlinear faults effectively. Finally, a simulation example is included to validate the advantages of the proposed approaches. © 1993-2012 IEEE.


Tong S.C.,Liaoning University of Technology | Li Y.M.,Liaoning University of Technology | Zhang H.-G.,Northeastern University China
IEEE Transactions on Neural Networks | Year: 2011

In this paper, two adaptive neural network (NN) decentralized output feedback control approaches are proposed for a class of uncertain nonlinear large-scale systems with immeasurable states and unknown time delays. Using NNs to approximate the unknown nonlinear functions, an NN state observer is designed to estimate the immeasurable states. By combining the adaptive backstepping technique with decentralized control design principle, an adaptive NN decentralized output feedback control approach is developed. In order to overcome the problem of explosion of complexity inherent in the proposed control approach, the dynamic surface control (DSC) technique is introduced into the first adaptive NN decentralized control scheme, and a simplified adaptive NN decentralized output feedback DSC approach is developed. It is proved that the two proposed control approaches can guarantee that all the signals of the closed-loop system are semi-globally uniformly ultimately bounded, and the observer errors and the tracking errors converge to a small neighborhood of the origin. Simulation results are provided to show the effectiveness of the proposed approaches. © 2011 IEEE.


Grant
Agency: Department of Health and Human Services | Branch: National Institutes of Health | Program: STTR | Phase: Phase I | Award Amount: 225.00K | Year: 2015

DESCRIPTION provided by applicant Atrial fibrillation AF is the most common diagnosed arrhythmia with the number Americans diagnosed with AF estimated at million and continuing to increase as the population ages Electrical activity during AF is characterized by complex activation patterns that are difficult to map However there is growing evidence that AF is driven by stable sources in the atria such as rotors or focal activity The most widely used ablation and surgical interventions to treat patients with AF use generalized empiric strategies that target that do not consider the specific mechanisms of the arrhythmia To date there are no established methods utilizing AF electrograms that effectively locate AF sources in the atria We have recently developed an electrogram morphology recurrence analysis that has been able to identify areas of the atria that have high rates of electrogram morphology recurrence Our preliminary study has shown that in patients who underwent ablation targeting the pulmonary veins when the electrograms with highest recurrence rates were located in the left versus right atrium ablation success rates were higher In contrast having these fast recurring electrograms in the right atrium indicated a very poor ablation success rate Additionally high resolution electrical mapping performed in a canine model of AF showed that morphology recurrence mapping could identify areas of rotor activity These preliminary data suggest that a mapping and ablation strategy based on morphology recurrence analysis could be used in the treatment of AF Phase I of this study involves the development of a prototype mapping software that can generate electrogram morphology recurrence maps in a real time clinical setting and the evaluation of this system on ablation in ten patients who have previously failed conventional AF ablation The mapping software will collect digital recordings from a basket catheter positioned in the right atrium and then the left atrium The maps will provide easy identification of the site with high morphology recurrence which can be related back to the anatomy with electroanatomic mapping If sites of high morphology recurrence rates represent areas at or near rotors or focal sources then we expect either acute termination of the AF or significant slowing of the AF activation rate A successful Phase I study showing that ablation via recurrence mapping produces AF termination or slowing in the majority of the ten patients would support the need for a larger study with longer term follow up Commercialization possibilities for this mapping approach include the production of a stand alone system or integration into an existing mapping system PUBLIC HEALTH RELEVANCE Atrial fibrillation AF is rapidly emerging health issue in the United States particularly among the elderly Currently used ablation and surgical approaches to treat AF utilize empirically determined strategies targeting the pulmonary veins This project investigates a novel electrogram mapping technique that may provide patient specific information regarding AF sources in the atria


Zhai Y.,Fudan University | Dou Y.,Northeastern University China | Zhao D.,Fudan University | Fulvio P.F.,Oak Ridge National Laboratory | And 2 more authors.
Advanced Materials | Year: 2011

Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liang R.-Q.,Northeastern University China | Masahiro K.,University of Toronto
Chinese Physics Letters | Year: 2014

A three-dimensional direct numerical simulation is carried out to predict the surface oscillation and flow structure of isothermal liquid bridges of 5 cSt silicone oil held vertically between solid disks. By subjecting liquid bridges to various horizontal vibrations, the surface resonance frequencies are clearly determined numerically and compared well with the existing analytical model predictions. The investigation on the flow structure inside the liquid bridge reveals, for the first time, the flow structure and the existence of transversal vortices inside the liquid bridge when a horizontal vibration is applied. © 2014 Chinese Physical Society and IOP Publishing Ltd.


Gao Z.-D.,Northeastern University China | Guan F.-F.,Northeastern University China | Li C.-Y.,Nanjing University | Liu H.-F.,Northeastern University China | Song Y.-Y.,Northeastern University China
Biosensors and Bioelectronics | Year: 2013

In this study, a novel signal-amplified electrochemical immunosensor was proposed by using TiO2 nanotube (TiNT) arrays as the platform. Due to the distinct tubular features-large surface area, high pore volume and good electrochemical conductivity, the TiNT based electrodes exhibited excellent signal-amplified effects. gold nanoparticle (AuNP) was further utilized to bind horseradish peroxidase (HRP) tagged antibodies as recognition elements. Compared to the immunosensor based on either flat electrode, the immunosensors using TiNT layer as electrode showed higher amplified electrochemical signals from the catalytic reaction of HRP relative to hydrogen peroxide (H2O2). Under optimal conditions, the proposed immunosensor exhibited a good electrochemical behavior to antigen in a concentration range from 0.1ngmL-1 to 105ngmL-1 with a detection limit of 0.01ngmL-1. The results showed that the TiNT-based electrochemical immunosensing platform could provide a great potential in clinical application for detection of low-abundant proteins. © 2012 Elsevier B.V.


Du Z.,Jiangsu University of Science and Technology | Zhang Q.,Northeastern University China | Liu L.,Northeastern University China
Asian Journal of Control | Year: 2011

The robust stability of discrete singular systems with time-varying delay is considered. New delay-dependent stability criteria are proposed, which are dependent on the minimum and maximum delay bounds. A strict delay-dependent linear matrix inequality (LMI) condition is obtained for a discrete singular time-varying system to be regular, causal and stable. The result on robust stabilization of uncertain discrete singular time-varying systems is also obtained and expressed in terms of LMIs. Numerical examples are given to demonstrate the applicability of the proposed method. © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.


Li W.,Ludong University | Liu X.,Ludong University | Zhang S.,Northeastern University China
Automatica | Year: 2012

This paper aims to relax the results in Xie and Tian (2009) from the following two aspects: completely removing the power order restriction and largely relaxing the growth conditions of nonlinear functions. By using the backstepping design method and homogeneous domination technique, this paper investigates the problem of adaptive state-feedback stabilization for a class of stochastic high-order nonlinear systems with nonlinear parameterization. The closed-loop system can be proved to be globally stable in probability and the states can be regulated to the origin almost surely. The efficiency of the adaptive state-feedback controller is demonstrated by a simulation example. © 2012 Elsevier Ltd. All rights reserved.


Song Y.-Y.,Northeastern University China | Zhuang Q.-L.,Northeastern University China | Li C.-Y.,Nanjing University | Liu H.-F.,Northeastern University China | And 2 more authors.
Electrochemistry Communications | Year: 2012

CdS nanocrystals (NCs) are decorated homogeneously on the TiO 2 nanotube arrays (TiNT) by chemical bath deposition method. The resultant CdS/TiNT composite shows largely amplified electrochemiluminescence (ECL) signals due to the vertically aligned nanotubular structure. The ultrasensitive antigen detection is achieved on the composites via an efficient ECL quenching process introduced by sandwiched immunoreaction, and shows a detection limit of 1.0 fg mL - 1. © 2012 Elsevier B.V. All rights reserved.


Liu P.,Shenyang University of Technology | Zhou X.,Shenyang University of Technology | Tang L.,Northeastern University China
International Journal of Advanced Manufacturing Technology | Year: 2010

A new scheduling model in which both two-agent and position-dependent processing times exist simultaneously is considered in this paper. Two agents compete to perform their respective jobs on a common single machine, and each agent has his own criterion to optimize. The job position-dependent processing time is characterized by increasing or decreasing function dependent on the position of a job in the sequence. We introduce an aging effect and a learning effect into the two-agent single-machine scheduling, where the objective is to minimize the total completion time of the first agent with the restriction that the maximum cost of the second agent cannot exceed a given upper bound. We propose the optimal properties for the considered scheduling problems and then present the optimal polynomial time algorithms to solve the two scheduling problems, respectively. © Springer-Verlag London Limited 2009.


Li W.,Ludong University | Jing Y.,Northeastern University China | Zhang S.,Northeastern University China
International Journal of Robust and Nonlinear Control | Year: 2012

This paper poses and solves a new problem of state feedback stabilization for a class of high-order stochastic nonlinear systems in which the power order restriction and growth condition are relaxed to a more general form. Based on the ideas of the homogeneous systems theory and the adding of a power integrator technique, a state feedback controller is constructed to ensure that the equilibrium at the origin of the closed-loop system is globally asymptotically stable in probability and that the problem of inverse optimal stabilization in probability is solved. The efficiency of the state feedback controller is demonstrated by a simulation example. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.


Zhang H.,Northeastern University China | Qin C.,Northeastern University China | Qin C.,Henan University | Luo Y.,Northeastern University China
IEEE Transactions on Automation Science and Engineering | Year: 2014

In this paper, a novel iterative two-stage dual heuristic programming (DHP) is proposed to solve the optimal control problems for a class of discrete-time switched nonlinear systems subject to actuators saturation. First, a novel nonquadratic performance functional is introduced to confront control constraints of the saturating actuator. Then, the iterative two-stage DHP algorithm is developed to solve the Hamilton-Jacobi-Bellman (HJB) equation of the switched system with the saturating actuator. Moreover, the convergence and optimality of the two-stage DHP algorithm are strictly proven. To implement this algorithm efficiently, there are two neural networks used as parametric structure to approximate the costate function and the corresponding control law, respectively. Finally, simulation results are given to verify the effectiveness of the proposed algorithm. © 2004-2012 IEEE.


Li F.,Shenyang University of Technology | Xie H.-L.,Northeastern University China
International Journal of Automation and Computing | Year: 2010

A visual servoing tracking controller is proposed based on the sliding mode control theory in order to achieve strong robustness against parameter variations and external disturbances. A sliding plane with time delay compensation is presented by the pre-estimate of states. To reduce the chattering of the sliding mode controller, a modified exponential reaching law and hyperbolic tangent function are applied to the design of visual controller and robot joint controller. Simulation results show that the visual servoing control scheme is robust and has good tracking performance. © 2010 Institute of Automation, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.


Wang Y.-L.,Jiangsu University of Science and Technology | Wang Y.-L.,Northeastern University China | Yang G.-H.,Northeastern University China
International Journal of Control | Year: 2010

This article studies the problem of H∞ controller design for networked control systems (NCSs) with time delay and packet dropout. A linear estimation-based time delay and packet dropout compensation method is proposed. The delay switching-based method is presented to deal with the variation of time delay, and H∞ controller design is presented for NCSs with packet dropout compensation by using linear matrix inequality (LMI)-based method. Then the combined delay switching and parameter uncertainty-based method is presented to model the variation of time delay, and H∞ controller design is also presented. The simulation results illustrate the effectiveness of the newly proposed linear estimation-based time delay and packet dropout compensation.


Song Y.-Y.,Northeastern University China | Gao Z.-D.,Northeastern University China | Wang J.-H.,Northeastern University China | Xia X.-H.,Nanjing University | Lynch R.,University of Limerick
Advanced Functional Materials | Year: 2011

WO3 nanoparticles loaded in TiO2 nanotube arrays, fabricated by a chemical bath deposition (CBD) technique in combination with a pyrolysis process, is uniform and the diameter can be easily adjusted by the deposition times. The resultant hybrid nanotubes array shows a multistage coloring electrochromic response at different potential bias. The formation of a 3-dimensional WO3/TiO2 junction promotes unidirectional charge transport due to the one-dimensional features of the tubes, which leads to the significant positive-shift onset potential of the cathodic reaction (ion insertion) and the highly increased proton storage capacity. Compared to non-decorated nanotube arrays, the enhanced electrochromic properties of longer lifetime, higher contrast ratio (bleaching time/coloration time), and improved tailored electrochromic behavior could be achieved using the composite films. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Li N.,CAS Beijing National Laboratory for Molecular | Li N.,Northeastern University China | Wang Z.,CAS Beijing National Laboratory for Molecular | Zhao K.,CAS Beijing National Laboratory for Molecular | And 3 more authors.
Carbon | Year: 2010

N-doped multi-layered graphene sheets were synthesized in large scale by the method of direct current arc-discharge between pure graphite rods. For the use of NH3 as one of the buffer gas, the multi-layered graphene sheets were doped with N without the addition of other nitrogen source. The product so obtained has been characterized by transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and element analysis. The graphene sheets are mainly of 2-6 layers and their sizes are about 100-200 nm. The multi-layered graphene sheets can be purified by a simple heat treatment process. The content of N atoms on the multi-layered graphene sheets can be tuned by simply changing the proportion of NH3 in the atmosphere. © 2009 Elsevier Ltd. All rights reserved.


Sun Y.,Shenyang Medical College | Ren Q.,Shenyang Medical College | Liu X.,Shenyang Medical College | Zhao S.,Northeastern University China | Qin Y.,Shenyang Medical College
Biosensors and Bioelectronics | Year: 2013

This study demonstrates a polyelectrolyte-free method to fabricate controllable and stable all-MWNTs films via a covalent layer-by-layer (LBL) deposition. Aminated MWNTs and carboxylated MWNTs were prepared by surface functionalization, allowing the incorporation of MWNTs into highly tunable thin films through the formation of covalent amide bonds. Fourier transform infrared spectroscopy (FTIR) analysis demonstrated the formation of covalent linkages between MWNTs layers. Scanning electron microscopy (SEM) and ultraviolet-visible spectroscopy (UV-vis) were used to characterize the assembly process. Electrochemical studies indicated that the all-MWNTs film possessed a remarkable electrocatalytic activity toward dihydronicotinamide adenine dinucleotide (NADH) at relatively low potentials, without the need for redox mediators. The film thickness and the amount of assembled MWNTs were readily adjusted by simply changing the number of cycles in the LBL assembly process, which also effectively tuned the electrocatalytic activity of the film toward NADH. The film constructed with four bilayers showed a high sensitivity of 223.8μAmM-1cm-2 and a detection limit of 1.5μM, with a fast response of less than 3s. Furthermore, the all-MWNTs film also showed good selectivity and excellent stability for the determination of NADH. © 2012 Elsevier B.V..


Liu Q.,Northeastern University China | Chai T.,Northeastern University China | Qin S.J.,University of Southern California
Control Engineering Practice | Year: 2012

The continuous annealing process line (CAPL) has complex process characteristics, such as strong correlation of a large number of process variables and interconnected multi-subsystems and multiple operation zones. Practitioners are concerned with typical process faults, such as strip-break and roll-slippage, whose effects are often confined in a specific zone. Considering the large-scale process characteristics and fault characteristics, a multi-block fault diagnosis method is proposed. A novel reconstruction-based block contribution (RBBC) is first proposed in order to diagnose the faulty block. The reconstruction-based variable contribution (RBVC) within a block is also proposed to determine the faulty variables. The proposed RBBC-RBVC hierarchical scheme is applied successfully to a real CAPL on two fault cases. A finite state machine is utilized to diagnose strip-break and reconstructed combined index is studied to diagnose roll-slippage. © 2012 Elsevier Ltd.


Li W.,Ludong University | Wei X.,Ludong University | Zhang S.,Northeastern University China
IET Control Theory and Applications | Year: 2012

In this study, the problem of decentralised output-feedback stabilisation is investigated for the first time for a class of large-scale high-order stochastic non-linear systems. By developing a decentralised high-gain homogeneous domination approach, we can completely relax the power order restriction which has been the common assumption for global stabilisation of high-order stochastic non-linear systems. It is shown that under some general conditions, the equilibrium of the closed-loop system is globally asymptotically stable (GAS) in probability when the drift and diffusion vector fields vanish at the origin. The efficiency of the output-feedback controller is demonstrated by a simulation example. © 2012 The Institution of Engineering and Technology.


Li W.,Ludong University | Jing Y.,Northeastern University China | Zhang S.,Northeastern University China
Automatica | Year: 2011

Under the more general conditions on the power order and the nonlinear functions, this paper investigates the problem of adaptive state-feedback stabilization for a class of high-order stochastic nonlinear systems with time-varying control coefficients. Based on the backstepping design method and homogeneous domination technique, the closed-loop system can be proved to be globally stable in probability and the states can be regulated to the origin almost surely. The efficiency of the state-feedback controller is demonstrated by a simulation example. © 2011 Elsevier Ltd. All rights reserved.


Zhang Y.,Northeastern University China | Zhou H.,Northeastern University China | Qin S.J.,University of Southern California | Chai T.,Northeastern University China
IEEE Transactions on Industrial Informatics | Year: 2010

In this paper, a decentralized fault diagnosis approach of complex processes is proposed based on multiblock kernel partial least squares (MBKPLS). To solve the problem posed by nonlinear characteristics, kernel partial least squares (KPLS) approaches have been proposed. In this paper, MBKPLS algorithm is first proposed and applied to monitor large-scale processes. The advantages of MBKPLS are: 1) MBKPLS can capture more useful information between and within blocks compared to partial least squares (PLS); 2) MBKPLS gives nonlinear interpretation compared to MBPLS; 3) Fault diagnosis becomes possible if number of sub-blocks is equal to the number of the variables compared to KPLS. The proposed methods are applied to process monitoring of a continuous annealing process. Application results indicate that the proposed decentralized monitoring scheme effectively captures the complex relations in the process and improves the diagnosis ability tremendously. © 2009 IEEE.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 70.00K | Year: 2010

Diver communication is vital for the US Navy while carrying out strategic underwater missions. Diver-to-diver communication and diver-to-vehicle communication can allow the sharing of information as it is discovered and also enable performing cooperative maneuvers. Emergency situations can also benefit from such communication. In addition to the communication capability, it would be useful to know the location of all the divers relative to the deployment vehicle during the mission. Such capability will allow operators on the deployment vehicle to guide the divers in their maneuvers and also provide immediate assistance during emergencies. Underwater acoustic communication presents unique challenges due to frequency selective fading, Doppler spread and multipath. A wearable underwater text messaging and location system (iDiver) based on multi carrier code division multi access (MC-CDMA) is proposed. The MC-CDMA protocol will help counteract intersymbol interference a key limitation in underwater acoustic communication. Location estimation will be performed using a combination of direction of arrival determination and inertial measurement units (IMUs). SCCI is collaborating with Prof. Stojanovic at Northeastern University, a leading expert in underwater communication. Phase I research will investigate the applicability of MC-CDMA to a network of divers. Phase II research will focus on hardware prototype development.


Patent
Northeastern University China and Shenyang University of Technology | Date: 2014-12-12

Provided are a double auxiliary resonant commutated pole three-phase soft-switching inverter circuit and a modulation method. The circuit includes a three-phase main inverter circuit and a three-phase double auxiliary resonant commutator circuit. An A-phase double auxiliary resonant commutator circuit, an A-phase main inverter circuit, a B-phase double auxiliary resonant commutator circuit, a B-phase main inverter circuit, a C-phase double auxiliary resonant commutator circuit and a C-phase main inverter circuit are connected in parallel in sequence and simultaneously connected with a DC power supply in parallel. The present invention can achieve the separation of the resonant current of the double auxiliary resonant commutator circuit from the load current at the moment of current commutation, thereby effectively reducing the current stress of the auxiliary switching tubes and the efficiency can be greatly increased particularly under light load condition.


Zhang C.,Northeastern University China | Ouyang D.,Key Laboratory of Symbol Computation and Knowledge Engineering | Ning J.,Northeast Normal University
Expert Systems with Applications | Year: 2010

Clustering is a popular data analysis and data mining technique. In this paper, an artificial bee colony clustering algorithm is presented to optimally partition N objects into K clusters. The Deb's rules are used to direct the search direction of each candidate. This algorithm has been tested on several well-known real datasets and compared with other popular heuristics algorithm in clustering, such as GA, SA, TS, ACO and the recently proposed K-NM-PSO algorithm. The computational simulations reveal very encouraging results in terms of the quality of solution and the processing time required. © 2009 Elsevier Ltd. All rights reserved.


Zhang H.,Northeastern University China | Liu Z.,Northeastern University China | Huang G.-B.,Nanyang Technological University | Wang Z.,Northeastern University China
IEEE Transactions on Neural Networks | Year: 2010

In this paper, a weighting-delay-based method is developed for the study of the stability problem of a class of recurrent neural networks (RNNs) with time-varying delay. Different from previous results, the delay interval [0, d(t)] is divided into some variable subintervals by employing weighting delays. Thus, new delay-dependent stability criteria for RNNs with time-varying delay are derived by applying this weighting-delay method, which are less conservative than previous results. The proposed stability criteria depend on the positions of weighting delays in the interval [0, d(t)], which can be denoted by the weighting-delay parameters. Different weighting-delay parameters lead to different stability margins for a given system. Thus, a solution based on optimization methods is further given to calculate the optimal weighting-delay parameters. Several examples are provided to verify the effectiveness of the proposed criteria. © 2009 IEEE.


Zhang H.,Northeastern University China | Ma T.,Northeastern University China | Huang G.-B.,Nanyang Technological University | Wang Z.,Northeastern University China
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2010

This paper is concerned with the robust exponential synchronization problem of a class of chaotic delayed neural networks with different parametric uncertainties. A novel impulsive control scheme (so-called dual-stage impulsive control) is proposed. Based on the theory of impulsive functional differential equations, a global exponential synchronization error bound together with some new sufficient conditions expressed in the form of linear matrix inequalities (LMIs) is derived in order to guarantee that the synchronization error dynamics can converge to a predetermined level. Furthermore, to estimate the stable region, a novel optimization control algorithm is established, which can deal with the minimum problem with two nonlinear terms coexisting in LMIs effectively. The idea and approach developed in this paper can provide a more practical framework for the synchronization of multiperturbation delayed chaotic systems. Simulation results finally demonstrate the effectiveness of the proposed method. © 2006 IEEE.


Qiu R.,Northeastern University China | Shang J.,University of Pittsburgh | Huang X.,Northeastern University China
International Journal of Production Economics | Year: 2014

We study the robust inventory decision-making problem faced by risk-averse managers with incomplete demand information in a newsvendor setting. Three basic models are developed: expected profit maximization, CVaR-based profit maximization, and a combination of the two. Each model is robustly formulated under the assumption of ellipsoid discrete distribution and again under the box discrete distribution. Each robust model can be mathematically transformed into a second-order cone program for ellipsoid uncertainty or into a general convex optimization problem for box uncertainty. Both transformed problems can be optimally solved directly. We offer propositions with proof to show the equivalence of the transformed problems with the original ones. Numerical examples are given to validate the proposed approach. We find that the performances under both ellipsoid and box uncertain distributions are robust. Finally, sensitivity analysis with respect to risk-averse levels and trade-off coefficients is conducted to validate the proposed models and solution approaches. © 2014 Elsevier B.V. All rights reserved.


Zhang H.,Northeastern University China | Liu Z.,Northeastern University China | Huang G.-B.,Nanyang Technological University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2010

This paper studies a class of new neural networks referred to as switched neutral-type neural networks (SNTNNs) with time-varying delays, which combines switched systems with a class of neutral-type neural networks. The less conservative robust stability criteria for SNTNNs with time-varying delays are proposed by using a new Lyapunov-Krasovskii functional and a novel series compensation (SC) technique. Based on the new functional, SNTNNs with fast-varying neutral-type delay (the derivative of delay is more than one) is first considered. The benefit brought by employing the SC technique is that some useful negative definite elements can be included in stability criteria, which are generally ignored in the estimation of the upper bound of derivative of Lyapunov-Krasovskii functional in literature. Furthermore, the criteria proposed in this paper are also effective and less conservative in switched recurrent neural networks which can be considered as special cases of SNTNNs. The simulation results based on several numerical examples demonstrate the effectiveness of the proposed criteria. © 2010 IEEE.


Dong J.,Northeastern University China | Wang Y.,Nanyang Technological University | Yang G.-H.,Northeastern University China
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2010

This paper considers the output feedback control problem for nonlinear discrete-time systems, which are represented by a type of fuzzy systems with local nonlinear models. By using the estimations of the states and nonlinear functions in local models, sufficient conditions for designing observer-based controllers are given for discrete-time nonlinear systems. First, a separation property, i.e., the controller and the observer can be independently designed, is proved for the class of fuzzy systems. Second, a two-step procedure with cone complementarity linearization algorithms is also developed for solving the H∞ dynamic output feedback (DOF) control problem. Moreover, for the case where the nonlinear functions in local submodels are measurable, a convex condition for designing H∞ controllers is given by a new DOF control scheme. In contrast to the existing methods, the new methods can design output feedback controllers with fewer fuzzy rules as well as less computational burden, which is helpful for controller designs and implementations. Lastly, numerical examples are given to illustrate the effectiveness of the proposed methods. © 2010 IEEE.


Wang S.,Northeastern University China | Ni P.,Queen's University
International Journal of Computational Methods | Year: 2014

Rock slopes stability has been one of the fundamental issues facing geotechnical engineering researchers. Due to the pre-existing joints, the intactness of the rock is weakened. The mechanical characteristics are changed correspondingly along with joint-induced stress redistribution within the rock mass if the sliding limit at the joint or part of it is exceeded. In this study, spatial block topological identification techniques are applied to distinguish all blocks cut by 3D finite random or fixed discontinuities. Based on the available photographic information of rock slopes, the sliding forces and the corresponding factor of safety are evaluated through limit equilibrium conditions by the classic block theory. The rock slope stability analysis software, GeoSMA-3D (Geotechnical Structure and Model Analysis), satisfying the requirements of spatial block modeling, joint plane simulation, key block identification and analysis and sliding process display, was developed. The application of such a software on the analysis of a rock slope, which is located near the inlet of Daiyuling No. 1 tunnel on the Zhuanghe-Gaizhou highway networks, was performed. The assessed results were compared with the monitored data to validate the effectiveness of such software. © World Scientific Publishing Company.


Peng X.-Y.,Dublin City University | Peng X.-Y.,Northeastern University China | Liu X.-X.,Northeastern University China | Diamond D.,Dublin City University | Lau K.T.,Dublin City University
Carbon | Year: 2011

An electrochemical synthesis method of reducing graphene oxide (GO) under constant potential is reported. Electrochemical technique offers control over reaction parameters such as the applied voltage, electrical current and reduction time; whereas the desired size and thickness of the film can be pre-determined by controlling the amount of precursor GO deposited on the electrode with defined shape and surface area. This synthesis technique produces high quality electrochemically reduced GO (ERGO) film with controllable size and thickness. Electrochemical symmetrical supercapacitors based on ERGO films achieved a specific capacitance of 128 F/g with an energy density of 17.8 Wh/kg operating within a potential window of 1.0 V in 1.0 M NaNO3. The supercapacitor was shown to be stable, retaining ca. 86% of the original specific capacitance after 3500 charge-discharge cycles. The results indicate that this simple synthesis technique for providing graphene-like materials has great potential in various applications such as energy storage. © 2011 Elsevier Ltd. All rights reserved.


Che W.-W.,Nanyang Technological University | Wang J.-L.,Nanyang Technological University | Yang G.-H.,Northeastern University China
IET Control Theory and Applications | Year: 2010

This study is concerned with the quantised H∞ filtering problem for discrete-time systems subject to limited communication capacity, which includes measurement quantisation and random sensor packet losses. By introducing an improved quantised random packet-loss model, the effects of the packet-loss rate and the upper bound of consecutive packet losses and the quantisation on the system performance are considered simultaneously. A quantised H∞ filter design strategy with the minimised static quantiser range is designed to guarantee the error system exponentially mean-square stable and also achieve the prescribed H∞ disturbance attenuation level. A numerical example is given to illustrate the effectiveness of the proposed filter design method. © 2010 The Institution of Engineering and Technology.


Yang G.-H.,Northeastern University China | Wang H.,Beijing University of Technology
IET Control Theory and Applications | Year: 2010

The study paper deals with sensor fault detection problem for a class of linear uncertain systems with bounded disturbances and non-zero constant reference inputs. The sensor faults are modelled as multi-mode, named as fault-free mode and faulty modes. A steady-state-based approach is proposed to detect the sensor faults. The steady-state-based approach can be used to detect lock-in-place sensor faults with arbitrary small magnitudes, which has not been well investigated in the literature. A convergent iterative algorithm based on linear matrix inequalities is given to obtain the solutions. A numerical example is given to illustrate the effectiveness of the proposed methods. © 2010 The Institution of Engineering and Technology.


Wang Z.,Northeastern University China | Yang D.,Northeastern University China | Ma T.,Chongqing University | Sun N.,Jilin Electrical Power Co.
Nonlinear Dynamics | Year: 2014

This work constructs a theoretical framework for the stability analysis of nonlinear fractional-order systems. A new definition, the generalized Caputo fractional derivative, is proposed for the first time. Based on that, the comparison principles for scalar and vector fractional-order systems are constructed, respectively. Furthermore, a sufficient theorem for stability analysis is proved, and how to use this theorem in stabilization is also discussed. Three examples have been presented to illustrate how to use the developed theory to analyze the stability and to design stabilization controllers. With the proposed method, the problems of stabilization and synchronization of the fractional-order chaotic fractional-order systems can be easily solved with linear feedback control. © 2013 Springer Science+Business Media Dordrecht.


Qiu R.,Northeastern University China | Shang J.,University of Pittsburgh
International Journal of Production Research | Year: 2014

We study robust multi-period inventory decisions for risk-averse managers with incomplete demand information for products with a short life cycle. The three inventory models we developed aim respectively to maximise expected profit, maximise conditional value-at-risk-based profit, and balance between the two objectives. We formulate each objective into an associated robust counterpart model under the assumption of ellipsoid distribution and again under the box distribution. The ellipsoid distribution-based robust model can be mathematically transformed into a non-linear programming which can be solved by finding solutions to some second-order cone programs, while the box distribution-based model can be converted into a general piecewise linear optimisation problem. We prove that the transformed versions are equivalent to the original ones and that both transformed models can be solved efficiently. Numerical examples are given to demonstrate the practicability of the proposed approach for dealing with uncertain demands. We find that the proposed optimisation approaches are robust under both the ellipsoid and box distributions. Finally, sensitivity analysis on the risk-averse degree and optimism index is conducted to validate the proposed models and solution approaches. © 2014 Taylor & Francis.


Zhang H.,Northeastern University China | Gong D.,Northeastern University China | Chen B.,Qingdao University | Liu Z.,Northeastern University China
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

This paper is concerned with the synchronization problems for an array of neural networks with hybrid coupling and interval time-varying delay. First, a novel augmented Lyapunov-Krasovskii functional (LKF) method is proposed to develop delay-dependent synchronization criteria for the networks, which makes use of more relaxed conditions by employing the new type of augmented matrices with Kronecker product operation. The proposed method can handle a multitude of Kronecker product operations in the LKF and alleviates the requirements of the positive definiteness of some conditional matrices which are usually considered in the existing methods for complex networks. This leads to a significant improvement in the performance of the synchronization criteria, i.e., less conservative synchronization results can be obtained. Meanwhile, the case of fast time-varying delay can also be handled by the proposed method. Furthermore, based on the derived criteria, a robust synchronization criterion is obtained for the system with uncertainties both in coefficient and coupling matrix terms. Since an expression based on linear matrix inequality is used, the proposed criteria can be easily checked in practice. Finally, numerical examples are provided to show the effectiveness of the proposed method. © 2012 IEEE.


Yang G.-H.,Northeastern University China | Wang H.,Beijing University of Technology
IEEE Transactions on Control Systems Technology | Year: 2010

This brief studies the problem of fault detection for a class of uncertain state-feedback tracking control systems with constant reference inputs and bounded disturbances. The considered systems are modeled via multiple modes, namely, fault-free case and faulty cases. Actuator stuck faults, including outage cases, are considered. With the aid of the finite-frequency positive-realness approach, a new linear-matrix-inequality-based fault detection method for control systems is obtained and applied to fault detection for flight control systems. An F-18 aircraft model is included in the simulation to illustrate the effectiveness of the proposed method. © 2009 IEEE.


Yang G.-H.,Northeastern University China | Wang H.,Beijing University of Technology | Xie L.,Nanyang Technological University
International Journal of Robust and Nonlinear Control | Year: 2010

The paper studies the fault detection problem for output feedback control systems with bounded disturbances and nonzero constant reference inputs. A steady-state-based approach is proposed which can be used to detect small actuator stuck faults including actuator outage (the stuck value is zero). These small stuck faults, especially the outage faults, cannot be detected effectively using the existing techniques. A dynamic output feedback controller and a weighting matrix are designed simultaneously. The dynamic output feedback controller stabilizes the closed-loop system for both fault-free and faulty cases and attenuates the effects of disturbances. By manipulating the steady-state values of system states with the detection weighting matrix, a residual is then generated, through which actuator stuck faults including actuator outages can be detected effectively. Simulation results are included to demonstrate our design procedure. Copyright © 2009 John Wiley & Sons, Ltd.


Dong J.,Northeastern University China | Dong J.,Nanyang Technological University | Wang Y.,Nanyang Technological University | Yang G.-H.,Northeastern University China
Fuzzy Sets and Systems | Year: 2011

This paper addresses the H∞ and mixed 2/H∞ control synthesis problems of nonlinear discrete-time systems, which are represented by a new type of T-S fuzzy models. The fuzzy systems consist of local nonlinear models and are with fewer fuzzy rules than the conventional T-S fuzzy systems with local linear models. A fuzzy control scheme with local nonlinear feedbacks is proposed and H∞ and mixed H2/H∞ control synthesis conditions are given in terms of solutions to a set of linear matrix inequalities (LMIs). In contrast to the existing conditions for designing fuzzy controllers, the new ones can be used to design fuzzy controllers based on fewer control rules as well as are with less computational burden. In particular, the new methods can also give less conservative results. A numerical example is given to illustrate the effectiveness of the proposed methods. © 2010 Elsevier B.V. All rights reserved.


Shen M.,Nanjing University of Technology | Ye D.,Northeastern University China
Fuzzy Sets and Systems | Year: 2013

This paper addresses the state feedback control of nonlinear continuous-time, Markovian-jump systems. The nonlinearity is represented by Takagi-Sugeno fuzzy models and the transition probability matrix is assumed to be partly known: some elements in the matrix are known, some are unknown but with known lower and upper bounds, and some are completely unknown. By making full use of the continuous property of the transition probability matrix, new sufficient conditions for the stochastic stability of the system are obtained in terms of linear matrix inequalities. We show that the conditions given are less conservative than or at least the same as those for existing results. Moreover, using the conditions obtained, we establish a method for design of a H ∞ state feedback controller. Numerical examples illustrate the effectiveness of the proposed method. © 2012 Elsevier B.V.


Wang S.,Northeastern University China | Ni P.,Queen's University | Guo M.,Northeastern University China
Tunnelling and Underground Space Technology | Year: 2013

It has been gaining credence over the past several decades that the spatial characteristics of rock joints exert detrimental effect on the stability of tunnel structures. The deterministic joint spatial distribution around the tunnel was defined by digital photogrammetry technique, which statistically provides the basis for performing Monte-Carlo simulation of stochastic joints that are hidden inside the surrounding rock. The blocks generated by the intersection between structural planes and excavation surfaces were analyzed based on the block theory and limit equilibrium. The keyblocks were identified and the corresponding factors of safety were determined. All these analysis procedures were codified into the computer program GeoSMA-3D (Geotechnical Structure and Model Analysis). The developed software satisfied the fast analysis requirements of joint plane simulation, spatial block modelling, keyblock identification and failure process illustration. The case study was performed with reference to Dabeigou Tunnel on Duolun Second-class Highway in Duolun Town, Nei Mongol, China. Failure process illustration would be useful to facilitate the practical engineers to understand the basic mechanism and select the strengthening strategies. © 2013 Elsevier Ltd.


Chen D.,Northeastern University China | Zhao H.,Northeastern University China | Zhao H.,Academy Neusoft Corporation
Proceedings - 2012 International Conference on Computer Science and Electronics Engineering, ICCSEE 2012 | Year: 2012

It is well-known that cloud computing has many potential advantages and many enterprise applications and data are migrating to public or hybrid cloud. But regarding some business-critical applications, the organizations, especially large enterprises, still wouldn't move them to cloud. The market size the cloud computing shared is still far behind the one expected. From the consumers' perspective, cloud computing security concerns, especially data security and privacy protection issues, remain the primary inhibitor for adoption of cloud computing services. This paper provides a concise but all-round analysis on data security and privacy protection issues associated with cloud computing across all stages of data life cycle. Then this paper discusses some current solutions. Finally, this paper describes future research work about data security and privacy protection issues in cloud. © 2012 IEEE.


Sui F.-L.,Anhui University of Technology | Xu L.-X.,Anhui University of Technology | Chen L.-Q.,Northeastern University China | Liu X.-H.,Northeastern University China
Journal of Materials Processing Technology | Year: 2011

Cylindrical specimens of Inconel 718 alloy with grain size of 90 μm were used in the compression tests and processing maps at the strains of 0.1, 0.3, 0.5 and 0.7 were developed at 950-1150 °C in the strain rate range 0.001-100 s-1. Only one unstable region for adiabatic shear bands and one small dynamic recrystallization zone in the stable region are exhibited in the processing map at 0.1 strain. As the strain is beyond 0.3, there exist three unstable regions in the processing maps where one is for adiabatic shear bands and the other two are for intergranular cracking. At the same time, the zone of dynamic recrystallization with a peak efficiency of 0.39 at about 950 °C and 0.001 s-1 in the stable region is enlarged and the distribution of which is from lower temperature and lower strain rate to higher ones. Optical micrographs of the specimens compressed to 0.7 strain show good agreement with the processing maps and main hot working schedules have been designed. Influence of initial grain size from 10 μm to 90 μm on the occurrence temperature of adiabatic shear bands and intergranular cracking has been analyzed at a strain rate of 100 s-1 and in the temperature range 900-1200 °C. © 2010 Elsevier B.V. All rights reserved.


Ip W.H.,Hong Kong Polytechnic University | Wang D.,Northeastern University China
IEEE Systems Journal | Year: 2011

To analyze the resilience of transportation networks, it is proposed to use a quantifiable resilience evaluation approach. First, we represent transportation networks by an undirected graph with the nodes as cities and edges as traffic roads. Because the survivability of transportation of a pair of cities depends on the number of passageways between them, the resilience of a city node can be evaluated by the weighted average number of reliable passageways with all other city nodes in the network. The network resilience can then be calculated by the weighted sum of the resilience of all nodes. To identify critical road lines or hub cities in networks, the concept of friability is proposed. This is defined as the reduction in total resilience upon removing an edge or hub city. Following the resilience and friability evaluation, a structure optimization model with a computational algorithm for transportation network design is recommended. Based on the recommended approaches, the resilience and friability of the railway network within the Chinese mainland is evaluated and analyzed. Several interesting conclusions are drawn from the computational results. The friability value of the railway lines in the Sichuan Basin which was damaged by the recent earthquake in China was also calculated. © 2010 IEEE.


Fu C.,Northeastern University China | Chen J.-J.,Northeastern University China | Zou H.,Northeastern University China | Meng W.-H.,Northern Hospital | And 2 more authors.
Optics Express | Year: 2012

Chaos-based image cipher has been widely investigated over the last decade or so to meet the increasing demand for real-time secure image transmission over public networks. In this paper, an improved diffusion strategy is proposed to promote the efficiency of the most widely investigated permutation-diffusion type image cipher. By using the novel bidirectional diffusion strategy, the spreading process is significantly accelerated and hence the same level of security can be achieved with fewer overall encryption rounds. Moreover, to further enhance the security of the cryptosystem, a plain-text related chaotic orbit turbulence mechanism is introduced in diffusion procedure by perturbing the control parameter of the employed chaotic system according to the cipher-pixel. Extensive cryptanalysis has been performed on the proposed scheme using differential analysis, key space analysis, various statistical analyses and key sensitivity analysis. Results of our analyses indicate that the new scheme has a satisfactory security level with a low computational complexity, which renders it a good candidate for real-time secure image transmission applications. © 2012 Optical Society of America.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 99.97K | Year: 2010

Triton Systems, Inc. and our partners, propose to develop a commercially viable process to print high speed thin film transistors (TFTs) onto large area flexible substrates. We propose to use a commercially available deposition system to deposit high mobility semiconductors onto flexible substrates. It uses an additive process with no masks or screens necessary. The printing technology is readily scalable to 1 x 3m sizes and larger. We also propose to increase the operating characteristics of the deposited TFTs (e.g. on/off ratio and mobilities). BENEFIT: This effort supports the Air Force’s desire for large area, flexible, high speed circuitry. The proposed effort will allow for such circuits to be produced quickly and economically at room temperature and pressures. A wide variety of military and commercial applications, such as wearable electronics, RFID, conformable sensors could benefit from the proposed effort.


Zheng C.-D.,Dalian Jiaotong University | Ma M.,Dalian Jiaotong University | Wang Z.,Northeastern University China
Neurocomputing | Year: 2011

In this paper, the state estimation problem is investigated for neural networks with time-varying delays as well as general activation functions. By applying the Finsler's Lemma and constructing appropriate Lyapunov-Krasovskii functional based on delay partitioning, several improved delay-dependent conditions are developed to estimate the neuron state with some available output measurements such that the error-state system is global asymptotically stable. It is established theoretically that one special case of the obtained criteria is equivalent to some existing result with same conservatism but including fewer LMI variables. As the present conditions involve no free-weighting matrices, the computational burden is largely reduced. Two examples are provided to demonstrate the effectiveness of the theoretical results. © 2010 Elsevier B.V.


Zhang F.,University of Chinese Academy of Sciences | Liu G.,Ryerson University | Fang L.,Northeastern University China | Wang H.,CAS Shenyang Institute of Automation
IEEE Transactions on Industrial Electronics | Year: 2012

Battery state-of-charge (SOC) estimation is essential for a mobile robot, such as inspection of power transmission lines. It is often estimated using a Kalman filter (KF) under the assumption that the statistical properties of the system and measurement errors are known. Otherwise, the SOC estimation error may be large or even divergent. In this paper, without the requirement of the known statistical properties, a SOC estimation method is proposed using an H ∞ observer, which can still guarantee the SOC estimation accuracy in the worst statistical error case. Under the conditions of different currents and temperatures, the effectiveness of the proposed method is verified in the laboratory and field environments. With the comparison of the proposed method and the KF-based one, the experimental results show that the proposed method can still provide accurate SOC estimation when there exist inexact or unknown statistical properties of the errors. The proposed method has been applied successfully to the robot for inspecting the running 500-kV extra high voltage power transmission lines. © 2011 IEEE.


Zheng C.-D.,Dalian Jiaotong University | Zhang H.,Northeastern University China | Wang Z.,Northeastern University China
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

The global exponential stability is analyzed for a class of high-order Hopfield-type neural networks with time-varying delays. Based on the Lyapunov stability theory, together with the linear matrix inequality approach and free-weighting matrix method, some less conservative delay-independent and delay-dependent sufficient conditions are presented for the global exponential stability of the equilibrium point of the considered neural networks. Two numerical examples are provided to demonstrate the effectiveness of the proposed stability criteria. © 2006 IEEE.


Xie F.,Northeastern University China | Zhang T.A.,Northeastern University China | Dreisinger D.,University of British Columbia | Doyle F.,University of California at Berkeley
Minerals Engineering | Year: 2014

Rare earth elements have unique physicochemical properties that make them essential elements in many high-tech components. Bastnesite (La, Ce)FCO 3, monazite, (Ce, La, Y, Th)PO4, and xenotime, YPO 4, are the main commercial sources of rare earths. Rare earth minerals are usually beneficiated by flotation or gravity or magnetic processes to produce concentrates that are subsequently leached with aqueous inorganic acids, such as HCl, H2SO4, or HNO3. After filtration or counter current decantation (CCD), solvent extraction is usually used to separate individual rare earths or produce mixed rare earth solutions or compounds. Rare earth producers follow similar principles and schemes when selecting specific solvent extraction routes. The use of cation exchangers, solvation extractants, and anion exchangers, for separating rare earths has been extensively studied. The choice of extractants and aqueous solutions is influenced by both cost considerations and requirements of technical performance. Commercially, D2EHPA, HEHEHP, Versatic 10, TBP, and Aliquat 336 have been widely used in rare earth solvent extraction processes. Up to hundreds of stages of mixers and settlers may be assembled together to achieve the necessary separations. This paper reviews the chemistry of different solvent extractants and typical configurations for rare earth separations. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.


Zheng C.-D.,Dalian Jiaotong University | Shan Q.-H.,Northeastern University China | Zhang H.,Northeastern University China | Wang Z.,Northeastern University China
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

The globally exponential stabilization problem is investigated for a general class of stochastic Cohen-Grossberg neural networks with both Markovian jumping parameters and mixed mode-dependent time-delays. The mixed time-delays consist of both discrete and distributed delays. This paper aims to design a memoryless state feedback controller such that the closed-loop system is stochastically exponentially stable in the mean square sense. By introducing a new Lyapunov-Krasovskii functional that accounts for the mode-dependent mixed delays, stochastic analysis is conducted in order to derive delay-dependent criteria for the exponential stabilization problem. Three numerical examples are carried out to demonstrate the feasibility of our delay-dependent stabilization criteria. © 2013 IEEE.


Zhang L.,Coventry University | Zhang L.,Northeastern University China | Potherat A.,Coventry University
Physics of Fluids | Year: 2013

An analysis of the successive regimes of the two-dimensional (2D) flow through a sharp 180° bend is performed by means of parametric numerical simulations where the Reynolds number Re and the opening ratio β (defined as the ratio of bend opening to the inlet width) vary in the respective ranges [0-2500] and [0.1-10]. In the outlet, the sequence of flow regimes is found to bear similarities with the flow behind a two-dimensional cylinder, despite being asymmetric by nature: when Re was increased, we found a laminar flow, then a flow with a first recirculation attached to the inside boundary, then one with a second recirculation attached to the top boundary. The onset of unsteadiness occurs through instability of the main stream and vortex shedding from the inside boundary. For β ≤ 0.2, the flow is characterised by the dynamics of the jet generated at the very small turning part whereas for β ≥ 0.3, it behaves rather like the flow behind an obstacle placed in a channel. This difference is most noticeable in the unsteady regimes where the vortex shedding mechanisms differ. While the former generates a more turbulent flow rich in small scale turbulence, the latter produces large structures of the size of the channel. In the turning part, further series of recirculation develop in each corner, akin to those identified by Moffatt ["Viscous and resistive eddies near a sharp corner," J. Fluid Mech.18, 1 (1964)10.1017/S0022112064000015]. For β > 1 corresponding eddies merge to form a series of alternately rotating recirculating cells, which occupy the whole width of the turning part. We find that for β > 1, the effective opening ratio β*, which correspond to the area occupied by the mainstream while passing from the inlet to the outlet, tends towards a value of ≃0.7. The combination of regimes in the outlet and the turning part yields a wealth of flow regimes, which open interesting possibilities to tailor the design of 180° bends to suit particular applications involving mixing, heat, and mass transfer. Selected 3D simulations show that with a few noticeable exceptions, 2D dynamics determine the main features of the flow (drag and recirculation length), even in a wide bend, while 3D structure tends to slow down the shedding mechanism. 2D simulations are thus not only relevant to configurations where the flow is expected to be 2D (thin bend, MHD flows), but also to 3D flows where they can predict some of the global flow features at a low computational cost. © 2013 AIP Publishing LLC.


Jia T.,University of British Columbia | Jia T.,Northeastern University China | Militzer M.,University of British Columbia
ISIJ International | Year: 2012

A unified model is proposed for the austenite-to-ferrite transformation kinetics in binary Fe-Mn alloys that accounts for solute drag of Mn. To aid the model development, continuous cooling transformation (CCT) tests were conducted for an interstitial-free steel that can be considered as Fe-0.1%Mn alloy. The experimental transformation data are supplemented with literature data for Fe-1%Mn and Fe-2%Mn alloys to establish a CCT database for Fe-Mn alloys. The austenite-to-ferrite transformation kinetics is described from a fundamental perspective by assuming an interface-controlled reaction and including solute drag of Mn. Using the solute drag model of Fazeli and Militzer, intrinsic interface mobility, trans-interface diffusivity of Mn and its binding energy have been determined from the CCT data. The interfacial parameters are critically analyzed and compared with independent measurements of diffusion and grain boundary segregation. © 2012 ISIJ.


Zheng C.-D.,Dalian Jiaotong University | Zhang H.,Northeastern University China | Wang Z.,Northeastern University China
IEEE Transactions on Neural Networks | Year: 2010

An augmented Lyapunov-Krasovskii functional (LKF) approach is presented to derive sufficient conditions for the existence, uniqueness, and globally exponential stability of the equilibrium point of a class of cellular neural networks with time-varying delays. By dividing the variation interval of the time delay into several subintervals with equal length, a novel vector LKF is introduced and new conditions are obtained based on the homeomorphism mapping principle, free-weighting matrix method, and linear matrix inequality techniques. Since the criteria are involving derivative information of both state and delay, the obtained results are less conservative than some previous ones. Two examples are also given to show the effectiveness of the presented criteria. © 2006 IEEE.


Li N.,Northeastern University China | Yuan H.,Northeastern University China | Sun H.,Shenyang Jianzhu University | Zhang Q.,Northeastern University China
Nonlinear Dynamics | Year: 2013

An impulsive multi-delayed feedback control strategy to control the period-doubling bifurcations and chaos in an n dimensional discrete system is proposed. This is an extension of the previous result in which the control method is applicable to the one-dimensional case. Then the application of the control method in a discrete prey-predator model is studied systematically, including the dynamics analysis on the prey-predator model with no control, the bifurcations analysis on the controlled model, and the bifurcations and chaos control effects illustrations. Simulations show that the period-doubling bifurcations and the resulting chaos can be delayed or eliminated completely. And the periodic orbits embedded in the chaotic attractor can be stabilized. Compared with the existed methods, a milder condition is needed for the realization of the proposed method. The condition may be considered as a generic case and we may state that almost all periodic orbits can be stabilized by the proposed method. Besides, the idea of impulsive control makes the implementation of the proposed control method easy. The impulsive interval is embodied in the analytical expression of the stability condition, hence can be chosen qualitatively according to the real needs, which is an extension of the existed related results. The introduction of multi-delay enlarges the domain of the control parameters and makes the selection of the control parameters have many choices, and hence become flexible. © 2012 Springer Science+Business Media B.V.


Feng J.,Northeastern University China | Wang S.,Northeastern University China | Zhao Q.,University of Alberta
IET Control Theory and Applications | Year: 2013

This study is concerned with the problem of fault detection (FD) for networked control systems with discrete and infinite distributed delays subject to random packet losses and non-linear perturbation. Both sensor-to-controller and controller-to-actuator packet losses are modelled as two different mutually independent Bernoulli distributed white sequences with known conditional probability distributions. By utilising an observer-based fault detection filter (FDF) as a residual generator, the FD for networked non-linear systems with mixed delays and packet losses is formulated as an H∞ modelmatching problem. Attention is focused on designing the FDF in the closed-loop system setup such that the estimation error between the residuals and filtered faults is made as small as possible and at the same time the closed-loop networked nonlinear system is exponentially stable in the mean-square sense. To show the superiority and effectiveness of this work, two numerical examples are presented. © 2013 The Institution of Engineering and Technology.


Zheng C.-D.,Dalian Jiaotong University | Zhang H.,Northeastern University China | Wang Z.,Northeastern University China
IEEE Transactions on Circuits and Systems II: Express Briefs | Year: 2010

Uniqueness and robust exponential stability are analyzed for a class of uncertain cellular neural networks with time-varying delays. By dividing the variation interval of the time delay into two subintervals with equal length, a novel LyapunovKrasovskii functional is introduced. Using the free-weighting matrix method, a new delay-dependent stability criterion is obtained, which is less conservative than some previous literature. Since the result is presented in terms of linear matrix inequalities, the condition is easy to be verified. Finally, an example is given to illustrate the effectiveness of our proposed method. © 2006 IEEE.


Zheng C.-D.,Dalian Jiaotong University | Zhang H.,Northeastern University China | Wang Z.,Northeastern University China
International Journal of Robust and Nonlinear Control | Year: 2013

The exponential stability problem is investigated for a class of uncertain stochastic neural networks with discrete and unbounded distributed time delays. Two types of uncertainty are considered: one is time-varying structured uncertainty, whereas the other is interval uncertainty. With the application of the Jensen integral inequality and constructing appropriate Lyapunov-Krasovskii functional based on delay partitioning, several improved delay-dependent criteria are developed to achieve the exponential stability in mean square in terms of linear matrix inequalities. It is established theoretically that two special cases of the obtained criteria are less conservative than some existing results but including fewer slack variables. As the present conditions involve fewer free weighting matrices, the computational burden is largely reduced. Three numerical examples are provided to demonstrate the effectiveness of the theoretical results. © 2012 John Wiley & Sons, Ltd.


Liu X.,Northeastern University China | Zhang H.,Northeastern University China | Dai J.,Georgia Institute of Technology
Fuzzy Sets and Systems | Year: 2010

This paper develops the delay-dependent robust and reliable H∞ fuzzy hyperbolic control for nonlinear large-scale interconnected systems with parameter uncertainties. Firstly, the modeling method of fuzzy hyperbolic model (FHM) is given for the general large-scale interconnected systems. The main advantages of using FHM over T-S fuzzy model are that neither premise structure identification nor completeness design of premise variables space is needed. Therefore the required computational effort is less than that of using T-S fuzzy model, especially when a lot of fuzzy rules are needed to model complex nonlinear systems. Then according to the Lyapunov direct method and the decentralized control theory of large-scale interconnected systems, linear matrix inequality (LMI)-based conditions with some free weighting matrices are derived, which guarantee the closed-loop interconnected systems to be robustly stable with the H∞ performance even in the presence of some possible actuator failures. Moreover, precise failure parameters of actuators are not required, and the only requirements are the lower and upper bounds of failure parameters. The restriction that the derivative of the time-varying delay is smaller than one is removed. Therefore, the results obtained are less conservative. Three simulation examples are provided to show the effectiveness of the proposed approach. © 2009 Elsevier B.V. All rights reserved.


Wang H.,Northeastern University China | Chen Y.,Communication University of China
Proceedings 2010 IEEE 5th International Conference on Bio-Inspired Computing: Theories and Applications, BIC-TA 2010 | Year: 2010

3D bin packing problem has attracted the wide concern from OR community due to their generalization in many realistic applications. In this paper, a hybrid genetic algorithm is proposed for 3DBPP. Within the framework of the proposed algorithm, a special diploid representation scheme of individual is designed and the heuristic packing methods, which are derived from a deepest bottom left with fill packing method, are employed to accomplish the translation from the individual to a solution. In order to further improve the performance of algorithm, several special GA operations are also designed in this paper. An experimental study over a set of 3DBPP test problems shows that the proposed algorithm is efficient and adaptable to address 3DBPP. © 2010 IEEE.


Xiao T.,Northeastern University China | Zhu J.,Northeastern University China | Liu T.,CAS Institute of Psychology
Artificial Intelligence | Year: 2013

In this article we address the issue of generating diversified translation systems from a single Statistical Machine Translation (SMT) engine for system combination. Unlike traditional approaches, we do not resort to multiple structurally different SMT systems, but instead directly learn a strong SMT system from a single translation engine in a principled way. Our approach is based on Bagging and Boosting which are two instances of the general framework of ensemble learning. The basic idea is that we first generate an ensemble of weak translation systems using a base learning algorithm, and then learn a strong translation system from the ensemble. One of the advantages of our approach is that it can work with any of current SMT systems and make them stronger almost "for free". Beyond this, most system combination methods are directly applicable to the proposed framework for generating the final translation system from the ensemble of weak systems. We evaluate our approach on Chinese-English translation in three state-of-the-art SMT systems, including a phrase-based system, a hierarchical phrase-based system and a syntax-based system. Experimental results on the NIST MT evaluation corpora show that our approach leads to significant improvements in translation accuracy over the baselines. More interestingly, it is observed that our approach is able to improve the existing system combination systems. The biggest improvements are obtained by generating weak systems using Bagging/Boosting, and learning the strong system using a state-of-the-art system combination method. © 2012 Elsevier B.V. All rights reserved.


Liu Z.,Hebei Normal University of Science and Technology | Zhong R.,Northeastern University China
Journal of Alloys and Compounds | Year: 2013

Green and red long lasting phosphorescent (LLP) phenomenon in γ-Zn3(PO4)2:Mn2+/Ga 3+was systematically investigated. Two emission bands are observed in γ-Zn3(PO4)2:Mn2+/Ga 3+, which are respectively centered at 507 nm and 620 nm. The green and the red long afterglow have been observed after removing the ultraviolet light. The spectral overlap between the green emission band and the excitation band monitored at 620 nm, which supports the feasibility of the energy transfer from Mn2+ (CN = 4) to Mn2+ (CN = 6), has been studied. The distribution of Mn2+ ions in tetrahedral and octahedral lattice changes with the incorporation of Ga3+ ions. The ratio of the green to the red enhances because of the increase of Ga3+ concentration. With the introduction of Ga3+, the color of the afterglow has been regulated, and the performance has been improved. © 2012 Elsevier B.V. All rights reserved.