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Bao Q.,National University of Singapore | Zhang H.,Nanyang Technological University | Zhang H.,Roosevelt University | Wang B.,Institute of Materials Research and Engineering of Singapore | And 5 more authors.
Nature Photonics | Year: 2011

Conventional polarizers can be classified into three main modes of operation: sheet polarizer using anisotropic absorption media, prism polarizer by refraction and Brewster-angle polarizer by reflection. These polarizing components are not easily integrated with photonic circuits. The in-line fibre polarizer, which relies on polarization-selective coupling between the evanescent field and birefringent crystal or metal, is a promising alternative because of its compatibility with most fibre-optic systems. Here, we demonstrate the operation of a broadband fibre polarizer based on graphene, an ultrathin two-dimensional carbon material. The out-coupled light in the telecommunication band shows a strong s-polarization effect with an extinction ratio of 27 dB. Unlike polarizers made from thin metal film, a graphene polarizer can support transverse-electric-mode surface wave propagation due to its linear dispersion of Dirac electrons. © 2011 Macmillan Publishers Limited. All rights reserved.

Zhou Y.J.,Shanghai University | Zhou Y.J.,Nanjing Southeast University | Yang B.J.,Shanghai University
Optics Express | Year: 2014

We propose a broadband slow wave system based on the thin metal-insulator-metal (MIM) graded grating structure composed of two corrugated metal strips with periodic array of grooves on a thin dielectric substrate. The guided spoof surface plasmon polaritons (SSPPs) at different frequencies can be localized at different positions along the ultrathin MIM grating. By introducing specially designed non-corrugated MIM branches with specific lengths at the locations where the EM waves are trapped, the trapped EM waves can be released and propagate along these branches. A 4-way wavelength demultiplexer based on such plasmonic broadband slow wave system is then demonstrated and fabricated. To improve the isolations between different branches at lower frequencies, band-reject filters are inserted at the front of some MIM branches. The measurements and the simulation results have shown very good agreements, which validate the feasibility of the 4-way wavelength demultiplexer. ©2014 Optical Society of America.

Chen S.,Huazhong University of Science and Technology | Du R.,Nanjing Southeast University
Energy | Year: 2011

Turbulent double-diffusive natural convection is of fundamental interest and practical importance. In the present work we investigate systematically the effects of thermal Rayleigh number (Ra), ratio of buoyancy forces (N) and aspect ratio (A) on entropy generation of turbulent double-diffusive natural convection in a rectangle cavity. Several conclusions are obtained: (1) The total entropy generation number (Stotal) increases with Ra, and the relative total entropy generation rates are nearly insensitive to Ra when Ra ≤ 109; (2) Since N > 1, Stotal increases quickly and linearly with N and the relative total entropy generation rate due to diffusive irreversibility becomes the dominant irreversibility; and (3) Stotal increases nearly linearly with A. The relative total entropy generation rate due to diffusive and thermal irreversibilities both are monotonic decreasing functions against A while that due to viscous irreversibility is a monotonic increasing function with A. More important, through the present work we observe a new phenomenon named as " spatial self-copy" in such convectional flow. The " spatial self-copy" phenomenon implies that large-scale regular patterns may emerge through small-scale irregular and stochastic distributions. But it is still an open question required further investigation to reveal the physical meanings hidden behind it. © 2011 Elsevier Ltd.

Li L.,Peking University | Li F.,CAS Institute of Electronics | Cui T.J.,Nanjing Southeast University
Optics Express | Year: 2014

This paper investigates the feasibility of the resonant metalens for the imaging beyond the diffraction limit using a single sensor in the farfield. It is shown that the resonant metalens can be related to the superresonance phenomenon. We demonstrate that the super-resonance supports the enhancement of the information capacity of an imaging system, which is responsible for the subwavelength imaging of the probed objects by using a single sensor in combination with a broadband illumination. Such imaging concept has its unique advantage of producing real-time data when an object is illuminated by broadband waves, without the harsh requirements such as near-field scanning, mechanical scanning, or antenna arrays. The proposed method is expected to find its applications in nanolithography, detection, sensing, and subwavelength imaging in the near future. © 2014 Optical Society of America.

Wan X.,Nanjing University of Posts and Telecommunications | Wu Z.,Nanjing Southeast University
Applied Acoustics | Year: 2013

Sound source localization plays a crucial role in many microphone arrays application, ranging from speech enhancement to human-computer interface in a reverberant noisy environment. The steered response power (SRP) using the phase transform (SRP-PHAT) method is one of the most popular modern localization algorithms. The SRP-based source localizers have been proved robust, however, the methods may fail to locate the sound source in adverse noise and reverberation conditions, especially when the direct paths to the microphones are unavailable. This paper proposes a localization algorithm based on discrimination of cross-correlation functions. The cross-correlation functions are calculated by the generalized cross-correlation phase transform (GCC-PHAT) method. Using cross-correlation functions, sound source location is estimated by one of the two classifiers: Naive-Bayes classifier and Euclidean distance classifier. Simulation results have demonstrated that the proposed algorithms provide higher localization accuracy than the SRP-PHAT algorithm in reverberant noisy environment. © 2012 Elsevier Ltd. All rights reserved.

Liu Y.,Zhejiang Normal University | Zhao S.,Shanghai University of Engineering Science | Lu J.,Nanjing Southeast University | Lu J.,Potsdam Institute for Climate Impact Research
IEEE Transactions on Fuzzy Systems | Year: 2011

In this paper, fuzzy impulsive control is used for stabilization of chaotic systems based on the TakagiSugeno (TS) model. The stability issue of the general nonlinear impulsive control system is first investigated via comparison criterion. Then, a novel impulsive control scheme is presented for chaotic systems based on the TS fuzzy model. Some sufficient conditions are given to stabilize the TS fuzzy model. Our results are proven to be less conservative theoretically and numerically. Moreover, we have also estimated the stable region of the impulsive interval. Finally, the proposed fuzzy impulsive control scheme is successfully applied to stabilize Rsslers system and Chuas circuit. The numerical simulations demonstrate the effectiveness and advantage of our main results. © 2010 IEEE.

Xu W.,University of Victoria | Xu W.,Nanjing Southeast University | Dong X.,University of Victoria | Lu W.-S.,University of Victoria
IEEE Transactions on Signal Processing | Year: 2010

Multi-antenna relaying has emerged as a promising technology to enhance the system performance in cellular networks. However, when precoding techniques are utilized to obtain multi-antenna gains, the system generally requires channel state information (CSI) at the transmitters. We consider a linear precoding scheme in a MIMO relaying broadcast channel with quantized CSI feedback from both two-hop links. With this scheme, each remote user feeds back its quantized CSI to the relay, and the relay sends back the quantized precoding information to the base station (BS). An upper bound on the rate loss due to quantized channel knowledge is first characterized. Then, in order to maintain the rate loss within a predetermined gap for growing SNRs, a strategy of scaling quantization quality of both two-hop links is proposed. It is revealed that the numbers of feedback bits of both links should scale linearly with the transmit power at the relay, while only the bit number of feedback from the relay to the BS needs to grow with the increasing transmit power at the BS. Numerical results are provided to verify the proposed strategy for feedback quality control. © 2010 IEEE.

He Y.,Open University Milton Keynes | Zhou D.,Nanjing Southeast University
Information Processing and Management | Year: 2011

Sentiment analysis concerns about automatically identifying sentiment or opinion expressed in a given piece of text. Most prior work either use prior lexical knowledge defined as sentiment polarity of words or view the task as a text classification problem and rely on labeled corpora to train a sentiment classifier. While lexicon-based approaches do not adapt well to different domains, corpus-based approaches require expensive manual annotation effort. In this paper, we propose a novel framework where an initial classifier is learned by incorporating prior information extracted from an existing sentiment lexicon with preferences on expectations of sentiment labels of those lexicon words being expressed using generalized expectation criteria. Documents classified with high confidence are then used as pseudo-labeled examples for automatical domain-specific feature acquisition. The word-class distributions of such self-learned features are estimated from the pseudo-labeled examples and are used to train another classifier by constraining the model's predictions on unlabeled instances. Experiments on both the movie-review data and the multi-domain sentiment dataset show that our approach attains comparable or better performance than existing weakly-supervised sentiment classification methods despite using no labeled documents. © 2010 Elsevier Ltd. All rights reserved.

Yang X.,Honghe University | Cao J.,Nanjing Southeast University | Lu J.,Nanjing Southeast University | Lu J.,Potsdam Institute for Climate Impact Research
Nonlinear Analysis: Real World Applications | Year: 2011

In this paper, the globally exponential synchronization of delayed complex dynamical networks with impulsive and stochastic perturbations is studied. The concept named "average impulsive interval" with "elasticity number" of impulsive sequence is introduced to get a less conservative synchronization criterion. By comparing with existing results, in which maximum or minimum of impulsive intervals are used to derive the synchronization criterion, the proposed synchronization criterion increases (or decreases) the impulse distances, which leads to the reduction of the control cost (or enhance the robustness of anti-interference) as the most important characteristic of impulsive synchronization techniques. It is discovered in our criterion that "elasticity number" has influence on synchronization of delayed complex dynamical networks but has no influence on that of non-delayed complex dynamical networks. Numerical simulations including a small-world network coupled with delayed Chua's circuit are given to show the effectiveness and less conservativeness of the theoretical results. © 2011 Elsevier Ltd. All rights reserved.

Xu L.Q.,National University of Singapore | Yang W.J.,National University of Singapore | Neoh K.-G.,National University of Singapore | Kang E.-T.,National University of Singapore | Fu G.D.,Nanjing Southeast University
Macromolecules | Year: 2010

An experiment was conducted to show that graphene oxide (GO) nanosheets can be readily reduced by dopamine with simultaneous capping by polydopamine to provide a versatile platform for covalent grafting of functional polymer brushes. Natural graphite flakes, dopamine hydrochloride O-[2-(3- mercaptopropionylamino) ethyl]-O0-methylpoly(ethylene glycol) (thiol-terminated PEG) and O-(2-aminoethyl)-O0-[2-(bocamino ethyl]poly(ethylene glycol) (amino-terminated PEG) were used. Graphite and NaNO3 were mixed with concentrated H2SO4 in a 250 mL flask at 0°C. The temperature was kept at 5°C, and the mixture was stirred for 2 h. After that, 7.3 g of KMnO4 was added in small portions to prevent temperature rise in excess of 20°C. Then, the temperature of the reaction mixture was raised to 35±2°C, and the mixture was stirred for 30 min. Fourier transform infrared spectroscopy measurements were carried out. The appearance of a strong absorption peak confirms that PEG brushes have been grafted on the PDA-capped RGO nanosheets.

Wen G.,Nanjing Southeast University | Duan Z.,Peking University | Chen G.,University of Hong Kong | Yu W.,Nanjing Southeast University | Yu W.,RMIT University
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2014

Distributed consensus tracking is addressed in this paper for multi-agent systems with Lipschitz-type node dynamics. The main contribution of this work is solving the consensus tracking problem without the assumption that the topology among followers is strongly connected and fixed. By using tools from M-matrix theory, a class of consensus tracking protocols based only on the relative states among neighboring agents is designed. By appropriately constructing Lyapunov function, it is proved that consensus tracking in the closed-loop multi-agent systems with a fixed topology having a directed spanning tree can be achieved if the feedback gain matrix and the coupling strength are suitably selected. Furthermore, with the assumption that each possible topology contains a directed spanning tree, it is theoretically shown that consensus tracking under switching directed topologies can be achieved if the control parameters are suitably selected and the dwell time is larger than a positive threshold. The results are then extended to the case where the communication topology contains a directed spanning tree only frequently as the system evolves with time. Finally, some numerical simulations are given to verify the theoretical analysis. © 2014 IEEE.

Xu W.,Nanjing Southeast University | Xu W.,Beijing Jiaotong University | Dong X.,University of Victoria
IEEE Transactions on Signal Processing | Year: 2012

This correspondence considers a MIMO relay downlink system using precoding and limited feedback. Since the conventional precoding matrices are directly obtained by treating the quantized channel state information (CSI) feedback as real CSI, we propose an optimized relay precoding strategy by taking both effects of channel quantization error and feedback delay into account. Conditioned on the outdated CSI quantization available at the relay station, the relay precoding is optimized via minimizing an expected mean-square error (MSE) criterion over CSI mismatches. By using Karush-Kuhn-Tucker (KKT) conditions, a closed-form solution to the relay design is achieved with comparable computational complexity relative to the conventional approach. Numerical results verify the effectiveness of the proposed scheme. © 1991-2012 IEEE.

Lin J.,Nanjing University of Posts and Telecommunications | Fei S.,Nanjing Southeast University | Gao Z.,Nanjing University of Posts and Telecommunications
Journal of the Franklin Institute | Year: 2012

This paper is concerned with the problem of state feedback stabilization of a class of discrete-time switched singular systems with time-varying state delay under asynchronous switching. The asynchronous switching considered here means that the switching instants of the candidate controllers lag behind those of the subsystems. The concept of mismatched control rate is introduced. By using the multiple Lyapunov function approach and the average dwell time technique, a sufficient condition for the existence of a class of stabilizing switching laws is first derived to guarantee the closed-loop system to be regular, causal and exponentially stable in the presence of asynchronous switching. The stabilizing switching laws are characterized by a upper bound on the mismatched control rate and a lower bound on the average dwell time. Then, the corresponding solvability condition for a set of mode-dependent state feedback controllers is established by using the linear matrix inequality (LMI) technique. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed method. © 2012 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.

Yu W.,Nanjing Southeast University | Yu W.,RMIT University | Ren W.,University of California at Riverside | Zheng W.X.,University of Western Sydney | And 2 more authors.
Automatica | Year: 2013

This paper discusses the design of distributed control gains for consensus in multi-agent systems with second-order nonlinear dynamics. First, an effective distributed adaptive gain-design strategy is proposed based only on local information of the network structure. Then, a leader-follower consensus problem in multi-agent systems with updated control gains is studied. A distributed adaptive law is then proposed for each follower based on local information of neighboring agents and the leader if this follower is an informed agent. Furthermore, a distributed leader-follower consensus problem in multi-agent systems with unknown nonlinear dynamics is investigated by combining the variable structure approach and the adaptive method. Finally, simulation examples are given to illustrate the theoretical analysis. © 2013 Published by Elsevier Ltd.

Zuo X.,National University of Singapore | Zuo X.,Nanjing Southeast University | Balasubramanian R.,National University of Singapore
Carbohydrate Polymers | Year: 2013

Novel poly(vinyl alcohol)/citric acid/chitosan (PVA/CA/CHT, PCC) beads were prepared as an adsorbent for the removal of trivalent chromium (Cr 3+) in aqueous solutions. PCC beads with different mass ratios (I, II, III, IV, V, ad VI) between PVA/CA/CHT were evaluated for the removal of Cr3+ ions to find an optimal stoichiometry of PCC beads, which indicated that the PCC bead (II) with the PVA/CA/CHT mass ratio of 1/5/1 showed the highest adsorption for Cr3+ ions. The surface characteristics of PCC beads (II) were determined by scanning electron microscopy using a field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR). The results obtained in this study implied that PCC bead (II) had an obviously rough and folded structure, and its spectrum manifested significant changes compared to those of PVA, CA and CHT. The sorption experiments were conducted to evaluate the performance of PCC beads (II) to adsorb Cr3+ ions in aqueous solutions. Results indicated that the Cr3+ ion sorption onto PCC beads (II) was highly pH-dependent with the maximum uptake at pH 6.0. The sorption kinetics data were well fitted by the pseudo-second-order equation with high regression coefficients. Sorption isotherm of PCC beads (II) was well described by Langmuir equation, with a maximum sorption at 41.5 mg Cr/g PCC beads (II). Desorption studies were also carried out by the repeated sorption/desorption experiments. The high efficiency and reusability of PCC beads (II) make them an attractive sorbent for the removal of Cr3+ and possibly other metals in aqueous solutions. © 2012 Elsevier Ltd.

Zhang J.,Nanjing University of Posts and Telecommunications | Zhang J.,Nanjing Southeast University | Qi L.,Nanjing University of Posts and Telecommunications | Zhu H.,Nanjing University of Posts and Telecommunications
IEEE Transactions on Wireless Communications | Year: 2012

Sensing-throughput tradeoff is involved in opportunistic spectrum access (OSA). At the physical layer it's expressed as the tradeoff between false alarm and misdetection, while at the MAC layer it's between maximizing the throughput of secondary users and reducing collisions with primary users. To balance both tradeoffs together drives the optimization of MAC frame structure for OSA. Since channel handoff results in a time overhead for MAC frame, it's first researched by modeling OSA dynamics in the paper. Three handoff cases and their probabilities are deduced, which lead to three application scenarios of MAC frame. Thus the throughput model of secondary network involving channel handoff is proposed. By balancing the misdetection and false alarm probabilities and maximizing the throughput of secondary network subject to the sensing quality and collision avoidance constraints, the optimal sensing time and frame duration are deduced as closed forms. The characteristics of the optimal MAC frame structure are researched as well. Theoretical and simulated results disclose the impacts of channel handoff and spectrum sensing on MAC frame structure and the achievable throughput of secondary network, which provide an insight for OSA design and improvement. © 2012 IEEE.

Fang Y.,Nanjing University of Posts and Telecommunications | Li P.,Nanjing Southeast University
Journal of Micromechanics and Microengineering | Year: 2013

Accurate determination of pull-in voltage and pull-in position is crucial in the design of electrostatically actuated microbeam-based devices. In the past, there have been many works on analytical modeling of the static pull-in of microbeams. However, unlike the static pull-in of microbeams where the analytical models have been well established, there are few works on analytical modeling of the dynamic pull-in of microbeam actuated by a step voltage. This paper presents two analytical approximate models for calculating the dynamic pull-in voltage and pull-in position of a cantilever beam and a clamped-clamped beam, respectively. The effects of the fringing field are included in the two models. The two models are derived based on the energy balance method. An N-order algebraic equation for the dynamic pull-in position is derived. An approximate solution of the N-order algebraic equation yields the dynamic pull-in position and voltage. The accuracy of the present models is verified by comparing their results with the experimental results and the published models available in the literature. © 2013 IOP Publishing Ltd.

Xu L.Q.,National University of Singapore | Neoh K.-G.,National University of Singapore | Kang E.-T.,National University of Singapore | Fu G.D.,Nanjing Southeast University
Journal of Materials Chemistry A | Year: 2013

Mercury pollution is a widespread problem. In this work, a solid-state sensor based on rhodamine derivative-modified cellulose filter papers for detection of Hg2+ ions in aqueous media is demonstrated. A three-step approach, involving the introduction of atom transfer radical polymerization (ATRP) initiating sites, surface-initiated ATRP (SI-ATRP) of pentafluorophenyl methacrylate, and post-functionalization of the reactive surface with amino-containing spirolactam rhodamine derivatives in ester-amine reaction, was developed for the covalent immobilization of mercury-responsive probes on the cellulose filter paper. This solid-state sensor exhibits highly selective recognition of Hg2+ ions in a Tris-HNO3 buffer solution (pH = 7.24) over various environmentally relevant metal ions with remarkably enhanced fluorescent emission intensity and distinct color change from colorless to pink. The response of a rhodamine derivative-modified cellulose filter paper to Hg2+ ions is fast (<2 min). The positive fluorescence response and color change of this functionalized filter paper thus provide a disposable solid-state sensor for fluorescent and "naked-eye" detection of Hg2+ ions. © 2013 The Royal Society of Chemistry.

Wang J.,Nanjing Southeast University
IEEE Transactions on Signal Processing | Year: 2013

In this paper, we propose a promising discrete game-theoretic framework for distributed energy efficient discrete spectrum sharing strategy selection (i.e., joint discrete power control and multimode precoding strategy selection) with limited feedback for cognitive MIMO interference channels. Given the competitive nature, the secondary users are assumed to be selfish and noncooperative, each of whom attempts to maximize its individual energy efficiency under a minimum data rate constraint and an interference power constraint. A mechanism for shutting down links is proposed to reduce interference and save energy. A payoff function is designed to guarantee the feasibility of the pure strategy Nash equilibrium with no need to know the infeasible strategy profiles (a spectrum sharing strategy profile is said to be feasible if the stated constraints are satisfied; otherwise, the spectrum sharing strategy profile is said to be infeasible, i.e., they may not satisfy the interference power constraint and minimum data rate constraint) in advance. We then investigate the existence and the feasibility of the pure strategy Nash equilibrium, and further devise a pricing-based distributed algorithm for spectrum strategy selection. The proposed algorithm is proved to converge to a feasible pure strategy Nash equilibrium under specific conditions. Moreover, by studying the relationship between our proposed game and the social optimum, we find that the pricing mechanism can result in Pareto improvement and lead to better convergence for the proposed distributed algorithm. Numerical results show that our designed algorithm significantly outperforms the random selection algorithm and the pricing mechanism has a dramatic effect in improving the system performance. © 1991-2012 IEEE.

Chen Z.,Nanjing Southeast University | Yin J.-J.,U.S. Food and Drug Administration | Zhou Y.-T.,U.S. Food and Drug Administration | Zhang Y.,Nanjing Southeast University | And 4 more authors.
ACS Nano | Year: 2012

Iron oxide nanoparticles (IONPs) are frequently used in biomedical applications, yet their toxic potential is still a major concern. While most studies of biosafety focus on cellular responses after exposure to nanomaterials, little is reported to analyze reactions on the surface of nanoparticles as a source of cytotoxicity. Here we report that different intracellular microenvironment in which IONPs are located leads to contradictive outcomes in their abilities to produce free radicals. We first verified pH-dependent peroxidase-like and catalase-like activities of IONPs and investigated how they interact with hydrogen peroxide (H 2O 2) within cells. Results showed that IONPs had a concentration- dependent cytotoxicity on human glioma U251 cells, and they could enhance H 2O 2-induced cell damage dramatically. By conducting electron spin resonance spectroscopy experiments, we showed that both Fe 3O 4 and γ-Fe 2O 3 nanoparticles could catalyze H 2O 2 to produce hydroxyl radicals in acidic lysosome mimic conditions, with relative potency Fe 3O 4 > γ-Fe 2O 3, which was consistent with their peroxidase-like activities. However, no hydroxyl radicals were observed in neutral cytosol mimic conditions with both nanoparticles. Instead, they decomposed H 2O 2 into H 2O and O 2 directly in this condition through catalase-like activities. Transmission electron micrographs revealed that IONPs located in lysosomes in cells, the acidic environment ofwhich may contribute to hydroxyl radical production. This is the first study regarding cytotoxicity based on their enzyme-like activities. Since H 2O 2 is continuously produced in cells, our data indicate that lysosome-escaped strategy for IONP delivery would be an efficient way to diminish long-term toxic potential. © 2012 American Chemical Society.

Li Z.,Peking University | Wen G.,Nanjing Southeast University | Duan Z.,Peking University | Ren W.,University of California at Riverside
IEEE Transactions on Automatic Control | Year: 2015

This technical note addresses the distributed consensus protocol design problem for multi-agent systems with general linear dynamics and directed communication graphs. Existing works usually design consensus protocols using the smallest real part of the nonzero eigenvalues of the Laplacian matrix associated with the communication graph, which however is global information. In this technical note, based on only the agent dynamics and the relative states of neighboring agents, a distributed adaptive consensus protocol is designed to achieve leader-follower consensus in the presence of a leader with a zero input for any communication graph containing a directed spanning tree with the leader as the root node. The proposed adaptive protocol is independent of any global information of the communication graph and thereby is fully distributed. Extensions to the case with multiple leaders are further studied. © 1963-2012 IEEE.

Wen G.,Peking University | Duan Z.,Peking University | Yu W.,Nanjing Southeast University | Chen G.,City University of Hong Kong
International Journal of Robust and Nonlinear Control | Year: 2013

This paper is concerned with the problem of consensus in directed networks of multiple agents with intrinsic nonlinear dynamics and sampled-data information. A new protocol is induced from a class of continuous-time linear consensus protocols by implementing data-sampling technique and a zero-order hold circuit. On the basis of a delayed-input approach, the sampled-data multi-agent system is converted to an equivalent nonlinear system with a time-varying delay. Theoretical analysis on this time-delayed system shows that consensus with asymptotic time-varying velocities in a strongly connected network can be achieved over some suitable sampled-data intervals. A multi-step procedure is further presented to estimate the upper bound of the maximal allowable sampling intervals. The results are then extended to a network topology with a directed spanning tree. For the case of the topology without a directed spanning tree, it is shown that the new protocol can still guarantee the system to achieve consensus by appropriately informing a fraction of agents. Finally, some numerical simulations are presented to demonstrate the effectiveness of the theoretical results and the dependence of the upper bound of maximal allowable sampling interval on the coupling strength. Copyright © 2012 John Wiley & Sons, Ltd.

Zhao Y.,Peking University | Duan Z.,Peking University | Wen G.,Nanjing Southeast University
International Journal of Robust and Nonlinear Control | Year: 2015

This paper investigates the distributed finite-time tracking problem of networked agents with multiple Euler-Lagrange dynamics. To achieve finite-time tracking, a distributed finite-time protocol is first proposed on the basis of both relative position and relative velocity measurements. By using tools from homogeneous theory, it is theoretically shown that the proposed protocol can guarantee finite-time tracking in the presence of control input constraints. On the basis of the state feedback analysis and with the aid of second-order sliding-mode observer approach, a new class of finite-time tracking protocols based only on the relative position measurements is developed and employed. It is proved that the multiple agents equipped with the designed protocols can track the target location in finite time. Furthermore, a decentralized finite-time protocol based on a distributed estimator is proposed to solve the finite-time tracking problems with a dynamic leader. The effectiveness of the theoretical results is finally illustrated by numerical simulations. Copyright © 2014 John Wiley & Sons, Ltd.

Yang X.,Honghe University | Cao J.,Nanjing Southeast University | Lu J.,Nanjing Southeast University
IEEE Transactions on Neural Networks and Learning Systems | Year: 2012

In this paper, a general model of coupled neural networks with Markovian jumping and random coupling strengths is introduced. In the process of evolution, the proposed model switches from one mode to another according to a Markovian chain, and all the modes have different constant time-delays. The coupling strengths are characterized by mutually independent random variables. When compared with most of existing dynamical network models which share common time-delay for all modes and have constant coupling strengths, our model is more practical because different chaotic neural network models can have different time-delays and coupling strength of complex networks may randomly vary around a constant due to environmental and artificial factors. By designing a novel Lyapunov functional and using some inequalities and the properties of random variables, we derive several new sufficient synchronization criteria formulated by linear matrix inequalities. The obtained criteria depend on mode-delays and mathematical expectations and variances of the random coupling strengths as well. Numerical examples are given to demonstrate the effectiveness of the theoretical results, meanwhile right-continuous Markovian chain is also presented. © 2012 IEEE.

Liu S.,Nanjing Southeast University | Chen H.,Nanjing Southeast University | Cui T.J.,Nanjing Southeast University
Applied Physics Letters | Year: 2015

We present the simulation, implementation, and measurement of a broadband terahertz (THz) metamaterial absorber. By stacking 12 metallic bars of varying lengths on three polyimide layers with equal spacing, a broadband absorption spectrum is formed through merging multiple successive resonance peaks. The measured total absorption exceeds 95% from 0.81 to 1.32 THz at the normal incidence and the full width at half maximum is 64% (from 0.76 to 1.48 THz). The absorption decreases with fluctuations as the incident angle increases but remains above 62% even at the incident angle of 40°. The physical explanation to the absorption mechanism is presented and verified by a 9-bar example, which exhibits narrower absorption bandwidth. It is also experimentally demonstrated that the proposed structure is robust against misalignment of each metallic layer. © 2015 AIP Publishing LLC.

Shi X.,Key Laboratory of Urban and Architectural Heritage Conservation | Shi X.,Nanjing Southeast University
Energy | Year: 2011

Architectural design is a process to find the best solution to satisfy various design criteria. To achieve sustainable and green design, performance simulations are often used to verify these criteria and modify the design. The conventional approach of manual trial-and-error is too time-consuming to be practical. Introducing optimization technique can greatly improve the design efficiency and help designers find the optimal design. In this paper, modeFRONTIER was used as the design optimization environment to find the best insulation strategy to minimize the space conditioning load of an office building located in Nanjing, China while keeping the insulation usage at minimum. EnergyPlus was integrated into the optimization tool by writing a DOS batch file to automate the work flow. The search engine was the genetic algorithm and it proved to be able to generate a well-defined Pareto frontier in a reasonable number of runs. Based on the Pareto frontier, the designer can specify his preferences and select the final design. The case study shows that an energy simulation program can be effectively integrated into a design optimization environment to find the optimal design. The technique presented has a broad application in architectural design, especially when the design considerations are multi-objective. © 2011 Elsevier Ltd.

Yu W.,Nanjing Southeast University | Yu W.,RMIT University | Chen G.,City University of Hong Kong | Cao M.,University of Groningen
IEEE Transactions on Automatic Control | Year: 2011

This technical note studies the consensus problem for cooperative agents with nonlinear dynamics in a directed network. Both local and global consensus are defined and investigated. Techniques for studying the synchronization in such complex networks are exploited to establish various sufficient conditions for reaching consensus. The local consensus problem is first studied via a combination of the tools of complex analysis, local consensus manifold approach, and Lyapunov methods. A generalized algebraic connectivity is then proposed to study the global consensus problem in strongly connected networks and also in a broad class of networks containing spanning trees, for which ideas from algebraic graph theory, matrix theory, and Lyapunov methods are utilized. © 2006 IEEE.

Dong H.Y.,Nanjing Southeast University | Dong H.Y.,Nanjing University of Posts and Telecommunications | Wang J.,Nanjing Southeast University | Cui T.J.,Nanjing Southeast University
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We demonstrate theoretically the existence of one-way Tamm plasmon polaritons on the interface between magnetophotonic crystals and conducting metal oxides. In contrast to conventional surface plasmon-polaritons (SPPs), Tamm plasmon polaritons (TPPs) occur at frequencies above the bulk plasma frequency of the conducting materials, provided that the dispersion curves of such surface modes lie outside the light cone for the conducting oxides and simultaneously fall into the photonic band gap of the magnetophotonic crystal. The nonreciprocal properties of TPPs are caused by violation of the periodicity and time-reversal symmetry in the structure. Calculations on the field distribution and transmission spectra through the structure are employed to confirm the theoretical results, which could potentially impact on a broad range of SPP-related phenomena in applications. © 2013 American Physical Society.

Li P.,Nanjing Southeast University | Fang Y.,Nanjing University of Posts and Telecommunications | Hu R.,Ningbo University of Technology
Journal of Sound and Vibration | Year: 2012

Predicting thermoelastic damping (TED) is crucial in the design of high Q micro-electro-mechanical systems (MEMS) resonators. In the past, some analytical models have been developed for TED in microbeam resonators. Rectangular and circular microplates are also common elements in many micro-resonators. Two analytical models have been developed for TED in the contour-mode vibration and the out-of-plane vibration of circular microplates, respectively. However, there is lack of works that model the TED in the out-of-plane vibration of rectangular microplates. This paper presents an analytical model for the TED in the fully clamped and simply supported rectangular microplates. The quality factor is found by calculating the energy dissipated per cycle of vibration over the volume of the microplate. The derivation in this paper shows that the model for the TED in the fully clamped and simply supported rectangular plates is the same as the model for the TED in the fully clamped and simply supported circular plates. For the rectangular microplates with other boundary conditions, based on Rayleighs method, this paper presents a set of analytical approximate models to estimate the TED in the rectangular microplates vibrating in the fundamental mode. The present model is validated by comparison with previously reported model and the FEM model. © 2011 Elsevier Ltd. All rights reserved.

Yang X.,Honghe University | Cao J.,Nanjing Southeast University | Lu J.,Nanjing Southeast University | Lu J.,Potsdam Institute for Climate Impact Research
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2012

In this paper, the global exponential synchronization of delayed complex dynamical networks with nonidentical nodes and stochastic perturbations is studied. By combining adaptive control and impulsive control schemes, the considered network can be synchronized onto any given goal dynamics. The adaptive control is discontinuous and can overcome the unknown difference between dynamical nodes and goal system. As for the impulsive control, the concept named average impulsive interval with elasticity number of impulsive sequence is utilized to get less conservative synchronization criterion. Numerical simulations are given to show the effectiveness and less conservativeness of the theoretical results. © 2012 IEEE.

Yang D.,Nanjing Southeast University | Lu X.,Nanjing Southeast University | Hong Y.,Nanjing Drum Tower Hospital | Xi T.,Peking University
Biomaterials | Year: 2013

To explore molecular mechanism of mediation of adsorbed proteins to cell adhesion and growth on biomaterials, this study examined endothelial cell adhesion, morphology and viability on bare and titanium nitride (TiN) coated nickel titanium (NiTi) alloys and chitosan film firstly, and then identified the type and amount of serum proteins adsorbed on the three surfaces by proteomic technology. Subsequently, the mediation role of the identified proteins to cell adhesion and growth was investigated with bioinformatics analyses, and further confirmed by a series of cellular and molecular biological experiments. Results showed that the type and amount of adsorbed serum proteins associated with cell adhesion and growth was obviously higher on the alloys than on the chitosan film, and these proteins mediated endothelial cell adhesion and growth on the alloys via four ways. First, proteins such as adiponectin in the adsorbed protein layer bound with cell surface receptors to generate signal transduction, which activated cell surface integrins through increasing intracellular calcium level. Another way, thrombospondin 1 in the adsorbed protein layer promoted TGF-β signaling pathway activation and enhanced integrins expression. The third, RGD sequence containing proteins such as fibronectin 1, vitronectin and thrombospondin 1 in the adsorbed protein layer bound with activated integrins to activate focal adhesion pathway, increased focal adhesion formation and actin cytoskeleton organization and mediated cell adhesion and spreading. In addition, the activated focal adhesion pathway promoted the expression of cell growth related genes and resulted in cell proliferation. The fourth route, coagulation factor II (F2) and fibronectin 1 in the adsorbed protein layer bound with cell surface F2 receptor and integrin, activated regulation of actin cytoskeleton pathway and regulated actin cytoskeleton organization. © 2013 Elsevier Ltd.

Yu W.,City University of Hong Kong | Yu W.,Nanjing Southeast University | Chen G.,City University of Hong Kong | Cao M.,University of Groningen
Automatica | Year: 2010

This paper studies some necessary and sufficient conditions for second-order consensus in multi-agent dynamical systems. First, basic theoretical analysis is carried out for the case where for each agent the second-order dynamics are governed by the position and velocity terms and the asymptotic velocity is constant. A necessary and sufficient condition is given to ensure second-order consensus and it is found that both the real and imaginary parts of the eigenvalues of the Laplacian matrix of the corresponding network play key roles in reaching consensus. Based on this result, a second-order consensus algorithm is derived for the multi-agent system facing communication delays. A necessary and sufficient condition is provided, which shows that consensus can be achieved in a multi-agent system whose network topology contains a directed spanning tree if and only if the time delay is less than a critical value. Finally, simulation examples are given to verify the theoretical analysis. © 2010 Elsevier Ltd. All rights reserved.

Yang L.,Guangdong University of Technology | Yang L.,Nanjing Southeast University | Gao X.,Nanjing Southeast University | Alouini M.-S.,King Abdullah University of Science and Technology
Journal of Lightwave Technology | Year: 2014

In this study, we consider a relay-assisted free-space optical communication scheme over strong atmospheric turbulence channels with misalignment-induced pointing errors. The links from the source to the destination are assumed to be all-optical links. Assuming a variable gain relay with amplify-and-forward protocol, the electrical signal at the source is forwarded to the destination with the help of this relay through all-optical links. More specifically, we first present a cumulative density function (CDF) analysis for the end-to-end signal-to-noise ratio. Based on this CDF, the outage probability, bit-error rate, and average capacity of our proposed system are derived. Results show that the system diversity order is related to the minimum value of the channel parameters. © 1983-2012 IEEE.

Wen G.,Peking University | Duan Z.,Peking University | Yu W.,Nanjing Southeast University | Chen G.,City University of Hong Kong
International Journal of Robust and Nonlinear Control | Year: 2012

The problem of second-order consensus is investigated in this paper for a class of multi-agent systems with a fixed directed topology and communication constraints where each agent is assumed to share information only with its neighbors on some disconnected time intervals. A novel consensus protocol designed based on synchronous intermittent local information feedback is proposed to coordinate the states of agents to converge to second-order consensus under a fixed strongly connected topology, which is then extended to the case where the communication topology contains a directed spanning tree. By using tools from algebraic graph theory and Lyapunov control approach, it is proved that second-order consensus can be reached if the general algebraic connectivity of the communication topology is larger than a threshold value and the mobile agents communicate with their neighbors frequently enough as the network evolves. Finally, a numerical example is simulated to verify the theoretical analysis. Copyright © 2011 John Wiley & Sons, Ltd.

Cao Y.,Air Force Research Lab | Yu W.,Nanjing Southeast University | Yu W.,RMIT University | Ren W.,University of California at Riverside | Chen G.,City University of Hong Kong
IEEE Transactions on Industrial Informatics | Year: 2013

This paper reviews some main results and progress in distributed multi-agent coordination, focusing on papers published in major control systems and robotics journals since 2006. Distributed coordination of multiple vehicles, including unmanned aerial vehicles, unmanned ground vehicles, and unmanned underwater vehicles, has been a very active research subject studied extensively by the systems and control community. The recent results in this area are categorized into several directions, such as consensus, formation control, optimization, and estimation. After the review, a short discussion section is included to summarize the existing research and to propose several promising research directions along with some open problems that are deemed important for further investigations. © 2005-2012 IEEE.

Li P.,Nanjing Southeast University | Fang Y.,Nanjing University of Posts and Telecommunications
Journal of Micromechanics and Microengineering | Year: 2010

Predicting squeeze-film damping in rare air is crucial for the design of high-Q MEMS devices. There have been two approaches to treating the squeeze-film damping in rare air: the approach using the effective viscosity coefficient and the approach using the molecular dynamics method. This paper focuses on the numerical simulation of squeeze-film damping in rare air using the molecular dynamics method. In the past, because of the heavy computational cost of simulation of a large particle system, the molecular dynamics approach was not often used to simulate the gas damping in the MEMS area. Hutcherson and Ye (2004 J. Micromech. Microeng. 14 1726-33) developed a novel molecular dynamics method to simulate the motion of a large number of molecules in the squeeze gas film in the free molecular regime. The method possesses high computational efficiency. However, in their work, the molecules entering into the interaction regime are represented by one computational molecule. Therefore, the method is unsuitable for the torsional plate and flexible microbeam. This paper presents a molecular dynamics approach for calculating the squeeze-film damping of the torsional microplate and flexible microbeam in the free molecular regime. In this approach, several computational molecules are used to represent all of the molecules interacting with the torsional microplate and flexible microbeam. The present paper is an extension of the work done by Hutcherson and Ye (2004 J. Micromech. Microeng. 14 1726-33). The accuracy of the present molecular dynamics approaches is verified by comparing their results with the experimental results available in the literature. © 2010 IOP Publishing Ltd.

Leng Y.,Nanjing Southeast University | Zhou X.,Peking University
Neuropsychologia | Year: 2014

When individuals play a gambling task and their actions have consequences for observers, how are the brain responses of the performers modulated by their interpersonal relationship with the observers? To address this issue, we examined the event-related potentials responses in performers while they played two gambling games: one during which they tried to earn money for the observers instead of themselves (i.e., Experiment 1) and another gambling game during which they attempted to earn money from the observers (i.e., Experiment 2). In Experiment 1, ERP results showed that when gambling for either the friends or the strangers, the feedback-related negativity (FRN) responses were more negative-going to the losses than to the gains. The FRN effect (loss minus gain) was significantly larger when gambling for the friends than for the strangers. The general P300 response was more positive-going when gambling for the friends than for the strangers. These results suggested that gambling for others enables individuals to assess the outcome from the interests of the other people, consequently, the FRN response may be driven by the evaluative process related to interests of the others. Because one's own economic interests were not involved, the performers' brain responses during both the early, semi-automatic stage (i.e., the FRN) and the later, controlled stage (i.e., the P300) of outcome evaluation were modulated by the interpersonal relationship between the performers and the observers. In Experiment 2, ERP results revealed that when gambling against others, the FRN response was more negative-going to the losses than to the gains, as well. However, neither the FRN effect nor the general FRN response was modulated by interpersonal relationship. The general P300 response was more positive-going when gambling against the stranger than against the friend. These results suggested that when gambling against others, the performers' FRN response may be driven by two evaluative processes: one is related to the interests of their own, and another is related to the interests of the other people; and the former one plays a dominant role. Because of highly self-involvement, only the performers' brain responses during the later controlled stage of outcome evaluation were modulated by interpersonal relationship. The present study extended previous research on brain responses to outcome evaluation when decision making actions have consequences for the other people by suggesting that the FRN response in the performer could also be driven by two evaluative processes. In addition, whether the FRN in the performer was modulated by interpersonal relationship depends on which evaluative process plays a dominant role. However, the P300 in the performer could always be modulated by interpersonal relationship. These findings provide evidence on outcome evaluation being composed of an early semi-automatic primitive process and a later controlled cognitive/affective appraisal process. © 2014 Elsevier Ltd.

Du B.,Nanjing Southeast University | Du B.,University of Adelaide | Hu E.,University of Adelaide | Kolhe M.,University College London
Renewable and Sustainable Energy Reviews | Year: 2012

The concentrated photovoltaic (CPV) system focuses solar radiation on the solar cells. CPV systems need to track the sun for keeping the reflected radiation focussed on the solar cell. A CPV module and its active water-cooling system are developed at the School of Energy and Environment, Southeast University, China and its performance has been reported here. This developed system has been used for testing the PV module's performance for different parameters such as operating temperature, power output, and efficiency. The experimental results show that the operating temperature of the CPV module under water cooling is reduced under 60°C and therefore the efficiency of the CPV has increased and produced the more electric power output. The effect of water flow rate has been analyzed for the CPV efficiency and output. © 2012 Elsevier Ltd.

Gao G.-H.,Nanjing University of Posts and Telecommunications | Gao G.-H.,Nanjing Southeast University | Sun Z.-Z.,Nanjing Southeast University | Zhang H.-W.,Tianjin Normal University
Journal of Computational Physics | Year: 2014

In the present work, first, a new fractional numerical differentiation formula (called the L1-2 formula) to approximate the Caputo fractional derivative of order α (0 < α < 1) is developed. It is established by means of the quadratic interpolation approximation using three points (t j -2, f(t j -2)), (t j -1, f(t j -1)) and (t j, f(t j)) for the integrand f(t) on each small interval [t j -1, t j] (j ≥ 2), while the linear interpolation approximation is applied on the first small interval [t0, t1]. As a result, the new formula can be formally viewed as a modification of the classical L1 formula, which is obtained by the piecewise linear approximation for f(t). Both the computational efficiency and numerical accuracy of the new formula are superior to that of the L1 formula. The coefficients and truncation errors of this formula are discussed in detail. Two test examples show the numerical accuracy of L1-2 formula. Second, by the new formula, two improved finite difference schemes with high order accuracy in time for solving the time-fractional sub-diffusion equations on a bounded spatial domain and on an unbounded spatial domain are constructed, respectively. In addition, the application of the new formula into solving fractional ordinary differential equations is also presented. Several numerical examples are computed. The comparison with the corresponding results of finite difference methods by the L1 formula demonstrates that the new L1-2 formula is much more effective and more accurate than the L1 formula when solving time-fractional differential equations numerically. © 2013 Elsevier Inc.

Yu W.,Nanjing Southeast University | Yu W.,City University of Hong Kong | Chen G.,City University of Hong Kong | Cao M.,University of Groningen
Systems and Control Letters | Year: 2010

Using tools from algebraic graph theory and nonsmooth analysis in combination with ideas of collective potential functions, velocity consensus and navigation feedback, a distributed leaderfollower flocking algorithm for multi-agent dynamical systems with time-varying velocities is developed where each agent is governed by second-order dynamics. The distributed leaderfollower algorithm considers the case in which the group has one virtual leader with time-varying velocity. For each agent i, this algorithm consists of four terms: the first term is the self nonlinear dynamics which determines the final time-varying velocity, the second term is determined by the gradient of the collective potential between agent i and all of its neighbors, the third term is the velocity consensus term, and the fourth term is the navigation feedback from the leader. To avoid an impractical assumption that the informed agents sense all the states of the leader, the new designed distributed algorithm is developed by making use of observer-based pinning navigation feedback. In this case, each informed agent only has partial information about the leader, yet the velocity of the whole group can still converge to that of the leader and the centroid of those informed agents, having the leader's position information, follows the trajectory of the leader asymptotically. Finally, simulation results are presented to demonstrate the validity and effectiveness of the theoretical analysis. Surprisingly, it is found that the local minimum of the potential function may not form a commonly believed α lattice. © 2010 Elsevier B.V. All rights reserved.

Miao Y.,Zhejiang Normal University | He N.,Nanjing Southeast University | Zhu J.-J.,Nanjing University
Chemical Reviews | Year: 2010

Biosensors based on ChE inhibition have been developed for monitoring pesticides in food and water samples. AChE hydrolyzes acetylcholine at a higher rate than butyrylcholine but is inhibited by excess substrate. On the other hand, although BChE hydrolyzes butyrylcholine at a higher rate than acetylcholine, it is not inhibited by excess substrate. A ChE inhibitor is known to suppress the activity of the enzyme. AChE inhibitors are traditionally divided into two groups: reversible and irreversible inhibitors. ChE-based assays give a sum parameter of ChE inhibition, and they are not usually capable of discriminating various toxic compounds in a multicomponent sample. Although laboratory testing is generally considered to provide more accurate results, field testing is often an effective alternative since it is faster and less expensive with simpler handling procedures amenable to both mass production and instrument miniaturization.

Su Z.,Nanjing Southeast University | Su Z.,Harvard University | Yang Z.,Kunming Medical University | Yang Z.,Kunming General Hospital of Chengdu Military Command | And 3 more authors.
Oncotarget | Year: 2015

MicroRNAs (miRNAs) are endogenous 22 nt non-coding RNAs that target mRNAs for cleavage or translational repression. Numerous miRNAs regulate programmed cell death including apoptosis, autophagy and necroptosis. We summarize how miRNAs regulate apoptotic, autophagic and necroptotic pathways and cancer progression. We also discuss how miRNAs link different types of cell death.

Liu Z.G.,National University of Singapore | Liu Z.G.,Nanjing Southeast University | Guo Y.X.,National University of Singapore
IEEE Transactions on Antennas and Propagation | Year: 2013

A dual band low profile antenna for wireless body centric communications is presented. It is composed of a concentric shorted annular ring and a circular patch. Two types of radiation patterns with omni-direction in azimuth plane at low frequency band for on-body communications and uni-direction in elevation plane at upper frequency band for off-body communications are obtained simultaneously. © 1963-2012 IEEE.

Jiang W.X.,Nanjing Southeast University | Qiu C.-W.,National University of Singapore | Han T.,National University of Singapore | Zhang S.,University of Birmingham | Cui T.J.,Nanjing Southeast University
Advanced Functional Materials | Year: 2013

The creation of wave-dynamic illusion functionality is of great interest to various scientific communities because it can potentially transform an actual perception into the pre-controlled perception, thus empowering unprecedented applications in the advanced-material science, camouflage, cloaking, optical and/or microwave cognition, and defense security. By using the space transformation theory and engineering capability of metamaterials, a functional "ghost" illusion device, which is capable of creating multiple virtual ghost images of the original object's position under the illumination of electromagnetic waves, is proposed and realized. The scattering signature of the object is thus ghosted and perceived as multiple ghost targets with different geometries and compositions. The ghost-illusion material, which is being inhomogeneous and anisotropic, is realized using thousands of varying unit cells working at non-resonance. The experimental demonstration of the ghost illusion validates the theory of scattering metamorphosis and opens a novel avenue to the wave-dynamic illusion, cognitive deception, manipulate strange light (or matter) behaviors, and design novel optical and microwave devices. A functional "ghost" illusion device that uses inhomogeneous and anisotropic materials and is capable of creating multiple virtual images off the original object's position under the illumination of electromagnetic waves is presented. The scattering signature of the object is thus perceived as multiple targets with different geometries and compositions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wu X.,Nanjing University of Posts and Telecommunications | Wu X.,Nanjing Institute of Communications Engineering | Zhao C.,Nanjing Southeast University | You X.,Nanjing Southeast University
IEEE Journal on Selected Areas in Communications | Year: 2013

For practical bi-directional relaying, symbols transmitted by two sources cannot arrive at the relay with perfect symbol and frame alignments and the asynchronous multiple-access channel (MAC) should be seriously considered. In this paper, we consider the Low-Density Parity-Check (LDPC)-coded BPSK signalling over the general asynchronous MAC with both frame and symbol misalignments. For the symbol-asynchronous MAC, we present a formal log-domain generalized sum-product-algorithm (Log-G-SPA) for efficient decoding. When the frame-asynchronism is encountered at the relay, we propose an original approach by employing the cyclic LDPC codes and the simple cyclic-redundancy-check (CRC) coding technique. Simulation results demonstrate the effectiveness of the proposed approach. © 1983-2012 IEEE.

Qi C.,Nanjing Southeast University | Yue G.,NEC Laboratories America Inc. | Wu L.,Nanjing Southeast University | Nallanathan A.,King's College London
IEEE Transactions on Vehicular Technology | Year: 2014

In this correspondence, sparse channel estimation is first introduced in orthogonal frequency-division multiplexing (OFDM)-based cognitive radio systems. Based on the results of spectrum sensing, the pilot design is studied by minimizing the coherence of the dictionary matrix used for sparse recovery. Then, it is formulated as an optimal column selection problem where a table is generated and the indexes of the selected columns of the table form a pilot pattern. A novel scheme using constrained cross-entropy optimization is proposed to obtain an optimized pilot pattern, where it is modeled as an independent Bernoulli random process. The updating rule for the probability of each active subcarrier selected as a pilot subcarrier is derived. A projection method is proposed so that the number of pilots during the optimization is fixed. Simulation results verify the effectiveness of the proposed scheme and show that it can achieve 11.5% improvement in spectrum efficiency with the same channel estimation performance compared with the least squares (LS) channel estimation. © 1967-2012 IEEE.

Lou Y.,Nanjing Southeast University | Zhao Y.,Shanghai JiaoTong University | Chen J.,Nanjing Southeast University | Zhu J.-J.,Nanjing University
Journal of Materials Chemistry C | Year: 2014

Colloidal semiconductor nanocrystals or quantum dots (QDs) have been facilitating the development of sensitive fluorescence sensors over the past decade, due to their unique photophysical properties, versatile surface chemistry and ligand binding ability, and the possibility of the encapsulation in different materials or attachment to different functional materials, while retaining their native luminescence property. The optical metal ion chemosensors with high sensitivity and selectivity have been developed due to the importance of the metal ions' fundamental roles, possessed in a wide range of biological processes and the aquatic environment. This review addresses the different sensing strategies with chemically modified QD hybrid structures for the sensing of metal ions in aqueous solution or an in vivo environment, and discusses the photophysical mechanisms in the different sensor systems while comparing their detecting/sensing selectivity. The perspectives for the future potential developments in QD based optical sensing for metal ions are discussed. © 2013 The Royal Society of Chemistry.

Chen S.,Nanjing Southeast University | Soto-Crespo J.M.,CSIC - Institute of Optics | Grelu P.,R.A.U.M.
Optics Express | Year: 2015

We investigate the resonant interaction of three optical pulses of different group velocity in quadratic media and report on the novel watch-hand-like super rogue wave patterns. In addition to having a giant wall-like hump, each rogue-wave hand involves a peak amplitude more than five times its background height. We attribute such peculiar structures to the nonlinear superposition of six Peregrine-type solitons. The robustness has been confirmed by numerical simulations. This stability along with the non-overlapping distribution property may facilitate the experimental diagnostics and observation of these super rogue waves. © 2015 Optical Society of America.

Chen S.,Nanjing Southeast University | Soto-Crespo J.M.,CSIC - Institute of Optics | Grelu P.,R.A.U.M.
Optics Express | Year: 2014

We investigate dark rogue wave dynamics in normally dispersive birefringent optical fibers, based on the exact rational solutions of the coupled nonlinear Schrödinger equations. Analytical solutions are derived up to the second order via a nonrecursive Darboux transformation method. Vector dark "three-sister" rogue waves as well as their existence conditions are demonstrated. The robustness against small perturbations is numerically confirmed in spite of the onset of modulational instability, offering the possibility to observe such extreme events in normal optical fibers with random birefringence, or in other Manakov-type vector nonlinear media. © 2014 Optical Society of America

Huidobro P.A.,Autonomous University of Madrid | Shen X.,Nanjing Southeast University | Cuerda J.,Autonomous University of Madrid | Moreno E.,Autonomous University of Madrid | And 4 more authors.
Physical Review X | Year: 2014

Here, we introduce the concept of magnetic localized surface plasmons (LSPs), magnetic dipole modes that are supported by cylindrical metal structures corrugated by very long, curved grooves. The resonance wavelength is dictated by the length of the grooves, allowing us to tune it to values much larger than the size of the particle. Moreover, magnetic LSPs also exist for extremely thin metal disks and, therefore, they could be used to devise metasurfaces with magnetic functionalities. Experimental evidence of the existence of these magnetic LSPs in the microwave regime is also presented, although the concept is very general and could be applied to terahertz or infrared frequencies.

He S.,Nanjing Southeast University | Huang Y.,Nanjing Southeast University | Yang L.,Nanjing Southeast University | Nallanathan A.,King's College London | Liu P.,Institute of Marine Electronic Equipment Research
IEEE Transactions on Wireless Communications | Year: 2012

In this paper, we address the problem of the coordinated beamforming design for multi-cell multiple input single output (MISO) downlink system subject to per-BS power constraints. The objective is taken as the maximization of the minimum signal-to-interference plus noise ratio (SINR), while a complete analysis of the duality between the multi-cell downlink and the virtual uplink optimization problems is provided. A hierarchical iterative scheme is proposed to solve the virtual uplink optimization problem, whose solution is then converted to derive the one of the multi-cell downlink beamforming problem. The proposed algorithm is proved to converge to a stable point. Additional, the complexity of the proposed algorithm is analyzed. Simulation results show that, in contrast to existing multi-cell beamforming schemes, the proposed algorithm achieves better performance in terms of both rate per energy (RPE) and the worst-user rate. © 2012 IEEE.

Xu J.,Nanjing University of Information Science and Technology | Chen M.,Nanjing University of Information Science and Technology | Fu D.,Nanjing Southeast University
Applied Surface Science | Year: 2011

Bi-doped hollow titania spheres were prepared using carbon spheres as template and Bi-doped titania nanoparticles as building blocks. The Bi-doped titania nanoparticles were synthesized at low temperature. The prepared hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-vis diffuse reflectance spectrum (DRS) and X-ray photoelectron spectroscopy (XPS). The effects of Bi content on the physical structure and photocatalytic activity of doped hollow titania sphere samples were investigated. Results showed that there was an optimal Bi-doped content (4%) for the photocatalytic degradation of methylene blue (MB). © 2011 Elsevier B.V. All rights reserved.

Chai J.,Saga University | Hong Z.,Nanjing Southeast University | Shen S.,Shanghai JiaoTong University
Geotextiles and Geomembranes | Year: 2010

The method of using a surface or subsurface soil layer as an air-sealing layer to carry out vacuum consolidation is referred to as the vacuum-drain method. A method of determining the vacuum-drain consolidation induced vacuum pressure distribution in the ground has been proposed based on unit cell finite element analysis results. With the calculated vacuum pressure distribution, a method for calculating the settlement-time curve and the lateral displacement profile at the edge of the vacuum consolidation area has been established. Finally, the proposed methods were applied to a project using the vacuum-drain method at Tokyo Bay in Japan. Comparing the calculated results with the measured field values indicates that the methods can be a useful tool for designing vacuum consolidation project. © 2010 Elsevier Ltd.

Wang J.,University of Connecticut | Gao R.X.,University of Connecticut | Yan R.,Nanjing Southeast University
Wind Energy | Year: 2014

Gearbox failure becomes a major concern for reliability of wind turbine because of complex repair procedures, long downtime and high replacement costs. Prior studies showed that the majority of gearbox failures were initiated from bearing failures. Because of the low signal-to-noise ratio (mixture of bearing defect signals and gear meshing signals) and transient nature of bearing signals, it poses significant difficulty for bearing defect diagnosis in wind turbine gearbox at the incipient stage. To address it, this paper presents an effective fault component separation method that integrates ensemble empirical mode decomposition (EEMD; an adaptive signal decomposition method in time-frequency domain) with independent component analysis (ICA; a blind source separation technique), without requiring a priori information on the rotating speeds or bandwidth. The method firstly decomposes one-channel vibration measurements into a series of intrinsic mode functions as pseudo-multi-channel signals, by means of EEMD. ICA is performed on the intrinsic mode functions to separate bearing defect-related signals from gear meshing signals. Envelope spectrum analysis is performed on the bearing defect-related signals to identify bearing structural defects. The effectiveness of the developed method in separating bearing defect-related signals from gear meshing signals for more effective fault diagnosis in bearings is evaluated and confirmed, numerically and experimentally. Copyright © 2013 John Wiley & Sons, Ltd.

You Y.,Nanjing Southeast University | You Y.,Columbia University | Zhang X.-X.,Columbia University | Berkelbach T.C.,Columbia University | And 3 more authors.
Nature Physics | Year: 2015

Transition metal dichalcogenide (TMDC) crystals exhibit new emergent properties at monolayer thickness, notably strong many-body effects mediated by Coulomb interactions. A manifestation of these many-body interactions is the formation of excitons, bound electron-hole pairs, but higher-order excitonic states are also possible. Here we demonstrate the existence of four-body, biexciton states in monolayer WSe 2. The biexciton is identified as a sharply defined state in photoluminescence at high exciton density. Its binding energy of 52 meV is more than an order of magnitude greater than that found in conventional quantum-well structures. A variational calculation of the biexciton state reveals that the high binding energy arises not only from strong carrier confinement, but also from reduced and non-local dielectric screening. These results open the way for the creation of new correlated excitonic states linking the degenerate valleys in TMDC crystals, as well as more complex many-body states such as exciton condensates or the recently reported dropletons. © 2015 Macmillan Publishers Limited. All rights reserved.

Jiang B.,Nanjing Southeast University | Gao F.,Nanjing Southeast University | Gao X.,Jacobs University Bremen | Nallanathan A.,King's College London
IEEE Transactions on Wireless Communications | Year: 2010

In this paper, we propose a new channel estimation prototype for the amplify-and-forward (AF) two-way relay network (TWRN). By allowing the relay to first estimate the channel parameters and then allocate the powers for these parameters, the final data detection at the source terminals could be optimized. Specifically, we consider the classical three-node TWRN where two source terminals exchange their information via a single relay node in between and adopt the maximum likelihood (ML) channel estimation at the relay node. Two different power allocation schemes to the training signals are then proposed to maximize the average effective signal-to-noise ratio (AESNR) of the data detection and minimize the meansquare-error (MSE) of the channel estimation, respectively. The optimal/sub-optimal training designs for both schemes are found as well. Simulation results corroborate the advantages of the proposed technique over the existing ones. © 2010 IEEE.

Chen S.,Nanjing Southeast University | Grelu P.,University of Burgundy | Soto-Crespo J.M.,CSIC - Institute of Optics
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

Exact explicit rogue-wave solutions of intricate structures are presented for the long-wave-short-wave resonance equation. These vector parametric solutions feature coupled dark- and bright-field counterparts of the Peregrine soliton. Numerical simulations show the robustness of dark and bright rogue waves in spite of the onset of modulational instability. Dark fields originate from the complex interplay between anomalous dispersion and the nonlinearity driven by the coupled long wave. This unusual mechanism, not available in scalar nonlinear wave equation models, can provide a route to the experimental realization of dark rogue waves in, for instance, negative index media or with capillary-gravity waves. © 2014 American Physical Society.

Chen S.,Nanjing Southeast University | Soto-Crespo J.M.,CSIC - Institute of Optics | Grelu P.,R.A.U.M.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

The coexistence of two different types of fundamental rogue waves is unveiled, based on the coupled equations describing the (2+1)-component long-wave-short-wave resonance. For a wide range of asymptotic background fields, each family of three rogue wave components can be triggered by using a slight deterministic alteration to the otherwise identical background field. The ability to trigger markedly different rogue wave profiles from similar initial conditions is confirmed by numerical simulations. This remarkable feature, which is absent in the scalar nonlinear Schrödinger equation, is attributed to the specific three-wave interaction process and may be universal for a variety of multicomponent wave dynamics spanning from oceanography to nonlinear optics. © 2014 American Physical Society.

Du Y.-J.,Nanjing Southeast University | Jiang N.-J.,Nanjing Southeast University | Shen S.-L.,Shanghai JiaoTong University | Jin F.,University of Cambridge
Journal of Hazardous Materials | Year: 2012

Remediation of contaminated lands in China urban areas is of great concern. Degradation of construction facilities caused by acid rain is a serious environmental pollution issue in China. This paper presents an investigation of the effects of acid rain on leaching and hydraulic properties of cement-based solidified/stabilized lead contaminated soil. Laboratory tests including infiltration test and soaking test are conducted. It is found that the soil hydraulic conductivity decreases with increase in the pore volume of flow of permeant liquids (acid rain and distilled water). The decreasing rate in the case of the acid rain is lower than that in the case of the distilled water. The soaking test results show that pH and the presence of sulfate ions of acid rain have considerable influence on the leached concentrations and leaching rate of calcium. © 2012 Elsevier B.V.

Yan R.,Nanjing Southeast University | Gao R.X.,University of Connecticut | Chen X.,Xi'an Jiaotong University
Signal Processing | Year: 2014

Over the last 20 years, particularly in last 10 years, great progress has been made in the theory and applications of wavelets and many publications have been seen in the field of fault diagnosis. This paper attempts to provide a review on recent applications of the wavelets with focus on rotary machine fault diagnosis. After brief introduction of the theoretical background on both classical wavelet transform and second generation wavelet transform, applications of wavelets in rotary machine fault diagnosis are summarized according to the following categories: continuous wavelet transform-based fault diagnosis, discrete wavelet transform-based fault diagnosis, wavelet packet transform-based fault diagnosis, and second generation wavelet transform-based fault diagnosis. In addition, some new research trends, including wavelet finite element method, dual-tree complex wavelet transform, wavelet function selection, new wavelet function design, and multi-wavelets that advance the development of wavelet-based fault diagnosis are also discussed. © 2013 Elsevier B.V.

Shariati N.,KTH Royal Institute of Technology | Wang J.,Nanjing Southeast University | Bengtsson M.,KTH Royal Institute of Technology
IEEE Transactions on Signal Processing | Year: 2014

We study how to design a worst-case robust training sequence for multiple-input multiple-output (MIMO) channel estimation. We consider mean-squared error of channel estimates as the figure of merit which is a function of second-order statistics of the MIMO channel, i.e., channel covariance matrix, in order to optimize training sequences under a total power constraint. In practical applications, the channel covariance matrix is not known perfectly. Thus the main aspect of our design is to improve robustness of the training sequences against possible uncertainties in the available channel covariance matrix. Using a deterministic uncertainty model, we formulate a robust training sequence design as a minimax optimization problem where we take such imperfections into account. We investigate the robust design problem assuming the general case of an arbitrarily correlated MIMO channel and a non-empty compact convex uncertainty set. We prove that such a problem admits a globally optimal solution by exploiting the convex-concave structure of the objective function, and propose numerical algorithms to address the robust training design problem. We proceed the analysis by considering multiple-input single-output (MISO) channels and Kronecker structured MIMO channels along with unitarily-invariant uncertainty sets. For these scenarios, we show that the problem is diagonalized by the eigenvectors of the nominal covariance matrices so that the robust design is significantly simplified from a complex matrix-variable problem to a real vector-variable power allocation problem. For the MISO channel, we provide closed-form solutions for the robust training sequences with the uncertainty sets defined by the spectral norm and nuclear norm. © 2013 IEEE.

Yan R.,Nanjing Southeast University | Gao R.X.,University of Connecticut
Journal of Sound and Vibration | Year: 2010

A filter construction technique is presented for enhanced defect identification in rotary machine systems. Based on the generalized harmonic wavelet transform, a series of sub-frequency band wavelet coefficients are constructed by choosing different harmonic wavelet parameter pairs. The energy and entropy associated with each sub-frequency band are then calculated. The filtered signal is obtained by choosing the wavelet coefficients whose corresponding sub-frequency band has the maximum energy-to-entropy ratio. Experimental studies using rolling bearings that contain different types of structural defects have confirmed that the developed new technique enables high signal-to-noise ratio for effective machine defect identification. © 2010 Elsevier Ltd. All rights reserved.

Yan R.,Nanjing Southeast University | Liu Y.,Anhui University | Gao R.X.,University of Connecticut
Mechanical Systems and Signal Processing | Year: 2012

This paper investigates the usage of permutation entropy for working status characterization of rotary machines. As a statistical measure, the permutation entropy describes complexity of a time series or signal measured on a physical system through phase space reconstruction, and takes into account non-linear behavior of the time series, as often seen in vibration signals of rotary machines. Thus it can be served as a viable tool for detecting dynamic changes of the machine working status. The effect of embedded dimension and time delay on calculation of the permutation entropy value has been studied, and the validity of the permutation entropy for detecting dynamic change of a physical system is studied through a well known non-linear system, the Logistic Map. Comparison with other complexity measures using a numerically formulated signal has also been investigated. Experimental results on bearing vibration analysis have then confirmed that the permutation entropy provides an effective measure for monitoring the working status of rolling bearings. © 2011 Elsevier Ltd. All rights reserved.

Rakkiyappan R.,Gandhigram Rural University | Balasubramaniam P.,Gandhigram Rural University | Cao J.,Nanjing Southeast University
Nonlinear Analysis: Real World Applications | Year: 2010

In this paper, by utilizing the Lyapunov-Krasovkii functional and combining with the linear matrix inequality (LMI) approach, we analyze the global exponential stability of neutral-type impulsive neural networks. In addition, an example is provided to illustrate the applicability of the result using LMI control toolbox in MATLAB. © 2008 Elsevier Ltd. All rights reserved.

Hou J.-M.,Nanjing Southeast University
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

First, we study a square fermionic lattice that supports the existence of massless Dirac fermions, where the Dirac points are protected by a hidden symmetry. We also consider two modified models with a staggered potential and the diagonal hopping terms, respectively. In the modified model with a staggered potential, the Dirac points exist in some range of magnitude of the staggered potential, and move with the variation of the staggered potential. When the magnitude of the staggered potential reaches a critical value, the two Dirac points merge. In the modified model with the diagonal hopping terms, the Dirac points always exist and just move with the variation of amplitude of the diagonal hopping. We develop a mapping method to find hidden symmetries evolving with the parameters. In the two modified models, the Dirac points are protected by this kind of hidden symmetry, and their moving and merging process can be explained by the evolution of the hidden symmetry along with the variation of the corresponding parameter. © 2014 American Physical Society.

Chen X.,Nanjing Southeast University | Shen C.,Nanjing Southeast University
Applied Optics | Year: 2012

A novel adaptive forward linear prediction (FLP) denoising algorithm and a temperature drift modeling and compensation concept based on ambient temperature change rate for fiber-optic gyroscope (FOG) are presented to calibrate the errors caused by intense ambient temperature variation. The intense ambient temperature variation will bring large temperature errors, which will degrade the performance of FOG. To analyze the temperature variation, characteristics of FOG temperature experiments are developed at first. Then the adaptive FLP denoising algorithm is employed to eliminate the noise aiming at reducing noise interference. After that, a simple modeling concept of building the compensation model between temperature drift and ambient temperature change rate is first to be given (we have not found a report of better results in any literature). The semiphysical simulation results show that the proposed method significantly reduces the noise and drift caused by intense ambient temperature variation. © 2012 Optical Society of America.

Shen C.,Nanjing Southeast University | Chen X.,Nanjing Southeast University
Applied Optics | Year: 2012

To explore and reduce the nonlinear error and temperature dependency of fiber-optic gyroscope (FOG) scale factor, a scale factor modeling method based on temperature is presented in this paper. A hyperbolic curve fitting is proposed according to the characteristic of scale factor under stable temperature at first. Compared to traditional modeling methods, it shows that a higher precision model of scale factor can be obtained. Then the influence of temperature on scale factor is analyzed and then the hyperbolic curve fitting method is extended based on temperature, making it possible to work over the whole potential temperature range of the FOG without degrading the performance. This paper also provides the experimental and verification results. It can be seen that a high precision model of scale factor has been established, the temperature dependency of scale factor has been reduced effectively, and the error due to environment temperature is reduced by one order at least. © 2012 Optical Society of America.

Xiao J.,Nanjing Southeast University | Sun X.,Nanjing Southeast University
Optics Communications | Year: 2010

A full-vectorial mode solver in terms of the transverse magnetic field components for optical waveguides with transverse anisotropy is described by using the multidomain spectral collocation method based on Chebyshev polynomials. The waveguide cross section surrounded by the perfectly matched layers is divided into suitable number of homogeneous rectangles, and then connected with by imposing the continuities of the longitudinal field components at the dielectric interfaces shared by the adjacent rectangles, resulting in a generalized matrix eigenvalue problem. To validate the established method, results of an anisotropic square waveguide and a magnetooptic rib waveguide are presented and compared with those from the fullvectorial finite difference method, full-vectorial beam propagation method, and the experimental data. © 2010 Elsevier B.V. All rights reserved.

Chen P.,Nanjing Southeast University
IEEE MTT-S International Microwave Workshop Series on Millimeter Wave Wireless Technology and Applications, IMWS 2012 - Proceeding | Year: 2012

A Micro-Electro-Mechanical System (MEMS) based Q band Substrate Integrated Waveguide (SIW) multi-beam antenna was designed, fabricated and measured. Fed by a 4x4 SIW Butler matrix, the prototype antenna can generate 4 beams simultaneously with respect to its 4 ports. The radiators of the proposed antenna are SIW transverse slots. At 45GHz, the measured 4 beam angles with respect to normal direction are -15°, -40°, 15° and 40°. © 2012 IEEE.

Chai L.,Nanjing Southeast University | Qian C.,University of Texas at San Antonio
Transactions of the Institute of Measurement and Control | Year: 2014

This paper addresses the problem of global output feedback stabilization for a class of uncertain nonlinear systems subject to time delay. Using the homogeneous domination approach, we first construct a homogeneous output feedback controller with an adjustable scaling gain. With the aid of a homogeneous Lyapunov-Krasovskii functional, the scaling gain is adjusted to dominate the time-delay nonlinearities bounded by homogeneous growth conditions and render the closed-loop system globally asymptotically stable. As a special case, a linear output feedback controller with a tunable scaling gain is constructed to globally stabilize time-delay systems under a linear growth condition. In addition, we also show the proposed approach is applicable to the time-delay systems under lower-order growth conditions and non-triangular growth conditions. © The Author(s) 2013.

He C.,Nanjing Southeast University | Li G.Y.,Georgia Institute of Technology | Zheng F.-C.,University of Reading | You X.,Nanjing Southeast University
IEEE Transactions on Vehicular Technology | Year: 2014

In this paper, we develop an energy-efficient resource-allocation scheme with proportional fairness for downlink multiuser orthogonal frequency-division multiplexing (OFDM) systems with distributed antennas. Our aim is to maximize energy efficiency (EE) under the constraints of the overall transmit power of each remote access unit (RAU), proportional fairness data rates, and bit error rates (BERs). Because of the nonconvex nature of the optimization problem, obtaining the optimal solution is extremely computationally complex. Therefore, we develop a low-complexity suboptimal algorithm, which separates subcarrier allocation and power allocation. For the low-complexity algorithm, we first allocate subcarriers by assuming equal power distribution. Then, by exploiting the properties of fractional programming, we transform the nonconvex optimization problem in fractional form into an equivalent optimization problem in subtractive form, which includes a tractable solution. Next, an optimal energy-efficient power-allocation algorithm is developed to maximize EE while maintaining proportional fairness. Through computer simulation, we demonstrate the effectiveness of the proposed low-complexity algorithm and illustrate the fundamental tradeoff between energy- and spectral-efficient transmission designs. © 1967-2012 IEEE.

Zhou F.,Nanjing Southeast University | Zhou F.,University of California at Los Angeles | Catton I.,University of California at Los Angeles
Numerical Heat Transfer; Part A: Applications | Year: 2011

A numerical investigation of the thermal and hydraulic performance of 20 different plate-pin fin heat sinks with various shapes of pin cross-sections (square, circular, elliptic, NACA profile, and dropform) and different ratios of pin widths to plate fin spacing (0.3, 0.4, 0.5, and 0.6) was performed. Finite volume method-based CFD software, Ansys CFX, was used as the 3-D Reynolds-averaged Navier-Stokes Solver. A k-ω based shear-stress-transport model was used to predict the turbulent flow and heat transfer through the heat sink channels. The present study provides original information about the performance of this new type of compound heat sink. Copyright © Taylor & Francis Group, LLC.

Zhang H.,Nanjing Southeast University | Shan Y.,Nanjing Southeast University | Dong L.,Nanjing Southeast University
Journal of Biomedical Nanotechnology | Year: 2014

The TiO2 and ZnO nanoparticles are the most promising next-generation photodynamic therapy (PDT) photosensitizers. This paper reports a one-to-one comparison of TiO2 and ZnO nanoparticles as photosensitizers in photodynamic therapy of cancer. After incubating SMMC-7721 hepatocarcinoma cells with TiO2 and ZnO nanoparticles, we irradiated the cells with ultraviolet (UV) light and formation of intracellular reactive oxygen species (ROS) was monitored using the dichloro-dihydro-fluorescein diacetate (DCFH-DA) method. The cytotoxicities of ZnO and TiO2 nanoparticles as photosensitizers in cancer PDT were evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, the mRNA and protein expression levels of apoptosis-related gene, including Bax, Bcl-2, and Caspase 3 were examined using RT-PCR and Western blot to elucidate the possible molecular mechanisms involved. Our results demonstrated that both TiO2 and ZnO nanoparticles could generate ROS within the tumor cells after irradiation, which in turn could attack the cancer cells. The caspase-dependent apoptosis was thus induced, resulting in anticancer activity. When the therapeutic effects were compared, no differences between the TiO2 and ZnO nanoparticles were observed for PDT. Either TiO 2 or ZnO nanoparticles can therefore be used in the near future as alternative photosensitizers in targeted tumor PDT when light is directly focused on the lesion. Copyright © 2014 American Scientific Publishers All rights reserved.

Zhang X.,Nanjing Southeast University | Xu Z.,University of Sichuan
Knowledge-Based Systems | Year: 2014

Hesitant fuzzy set (HFS) is used to deal with the situations in which the decision makers hesitate among several values to assess an indicator, alternative, variable, etc. Recently, the multi-criteria decision making (MCDM) problems with hesitant fuzzy information have received increasing attentions and many corresponding MCDM methods have also been developed, but none of them can be used to solve the MCDM problems in case of considering the decision maker's psychological behavior. In this study, we extend the TODIM (an acronym in Portuguese of interactive and multi-criteria decision making) method, which is based on prospect theory and can effectively capture the decision maker's psychological behavior, to solve this type of problems under hesitant fuzzy environment. Firstly, we develop two novel measured functions for comparing the magnitude of hesitant fuzzy elements and interval-valued hesitant fuzzy elements, which are more reasonable and effective compared with the existing measured functions. Then, we calculate the dominance degree of each alternative related to the others based on novel measured functions and distance measures. By aggregating these dominance degrees, we can further obtain the overall value of each alternative and whereby rank the alternatives. Finally, a decision making problem that concerns the evaluation and ranking of the service quality among domestic airlines is used to illustrate the validity and applicability of the proposed method. © 2014 Elsevier B.V. All rights reserved.

Zhao Y.,Nanjing Southeast University | Wu Q.,Nanjing Southeast University | Tang M.,Nanjing Southeast University | Wang D.,Nanjing Southeast University
Nanomedicine: Nanotechnology, Biology, and Medicine | Year: 2014

So far, we still know little about mechanism for recovery response of engineered nanomaterials (ENMs). Here we used Caenorhabditis elegans to investigate recovery responses of titanium dioxide nanoparticles (TiO2-NPs) exposed animals and the underlying mechanism. After acute exposure to TiO2-NPs (100mg/L), endpoints including defecation and permeable state of intestinal barrier of exposed nematodes returned to control levels; however, after prolonged exposure to TiO2-NPs (100μg/L), endpoints of exposed nematodes could not be recovered to control levels under the normal condition. After prolonged exposure to TiO2-NPs, nematodes exhibited severe deficits in development of intestinal barrier and AVL and DVB neurons controlling defecation; however, after acute exposure to TiO2-NPs, nematodes had normal developmental state of intestinal barrier and AVL and DVB neurons. Our results imply that developmental states of intestinal barrier and AVL and DVB neurons may serve as a pivotal determinant for recovery response in TiO2-NPs exposed nematodes. From the Clinical Editor: This basic science study investigates the recovery response to TiO2 nanoparticles in a nematode model, and concludes that developmental states of the intestinal barrier and AVL and DVB neurons likely serve as determinants for recovery following TiO2-NP exposure. © 2014 Elsevier Inc.

Jiang H.,Nanjing Southeast University | Zhang Y.,Nanjing Southeast University | Wang X.,Nanjing Southeast University
Nanoscale | Year: 2014

Ultra-small metallic nanoparticles, or so-called "nanoclusters" (NCs), have attracted considerable interest due to their unique optical properties that are different from both larger nanoparticles and single atoms. To prepare high-quality NCs, the stabilizing agent plays an essential role. In this work, we have revealed and validated that cytidine and its nucleotides (cytidine 5′-monophosphate or cytidine 5′-triphosphate) can act as efficient stabilizers for syntheses of multicolored Au NCs. Interestingly, Au NCs with blue, green and yellow fluorescence emissions are simultaneously obtained using various pH environments or reaction times. The transmission electron microscopy verifies that the size of Au NCs ranges from 1.5 to 3 nm. The X-ray photoelectron spectroscopy confirms that only Au (0) species are present in NCs. Generally, the facile preparation of multicolored Au NCs that are stabilized by cytidine units provides access to promising candidates for multiple biolabeling applications. © 2014 the Partner Organisations.

Zhu Q.,Ningbo University | Cao J.,Nanjing Southeast University
IEEE Transactions on Neural Networks | Year: 2010

This paper is concerned with the problem of exponential stability for a class of Markovian jump impulsive stochastic Cohen-Grossberg neural networks with mixed time delays and known or unknown parameters. The jumping parameters are determined by a continuous-time, discrete-state Markov chain, and the mixed time delays under consideration comprise both time-varying delays and continuously distributed delays. To the best of the authors' knowledge, till now, the exponential stability problem for this class of generalized neural networks has not yet been solved since continuously distributed delays are considered in this paper. The main objective of this paper is to fill this gap. By constructing a novel Lyapunov-Krasovskii functional, and using some new approaches and techniques, several novel sufficient conditions are obtained to ensure the exponential stability of the trivial solution in the mean square. The results presented in this paper generalize and improve many known results. Finally, two numerical examples and their simulations are given to show the effectiveness of the theoretical results. © 2006 IEEE.

Qin A.K.,Nanjing Southeast University | Clausi D.A.,University of Waterloo
IEEE Transactions on Image Processing | Year: 2010

Multivariate image segmentation is a challenging task, influenced by large intraclass variation that reduces class distinguishability as well as increased feature space sparseness and solution space complexity that impose computational cost and degrade algorithmic robustness. To deal with these problems, a Markov random field (MRF) based multivariate segmentation algorithm called "multivariate iterative region growing using semantics" (MIRGS) is presented. In MIRGS, the impact of intraclass variation and computational cost are reduced using the MRF spatial context model incorporated with adaptive edge penalty and applied to regions. Semantic region growing starting from watershed over-segmentation and performed alternatively with segmentation gradually reduces the solution space size, which improves segmentation effectiveness. As a multivariate iterative algorithm, MIRGS is highly sensitive to initial conditions. To suppress initialization sensitivity, it employs a region-level k-means (RKM) based initialization method, which consistently provides accurate initial conditions at low computational cost. Experiments show the superiority of RKM relative to two commonly used initialization methods. Segmentation tests on a variety of synthetic and natural multivariate images demonstrate that MIRGS consistently outperforms three other published algorithms. © 2006 IEEE.

He W.,East China University of Science and Technology | Cao J.,Nanjing Southeast University
IEEE Transactions on Neural Networks | Year: 2010

This paper investigates exponential synchronization of coupled networks with hybrid coupling, which is composed of constant coupling and discrete-delay coupling. There is only one transmittal delay in the delayed coupling. The fact is that in the signal transmission process, the time delay affects only the variable that is being transmitted from one system to another, then it makes sense to assume that there is only one single delay contributing to the dynamics. Some sufficient conditions for synchronization are derived based on Lyapunov functional and linear matrix inequality (LMI). In particular, the coupling matrix may be asymmetric or nondiagonal. Moreover, the transmittal delay can be different from the one in the isolated system. A distinctive feature of this work is that the synchronized state will vary in comparison with the conventional synchronized solution. Especially, the degree of the nodes and the inner delayed coupling matrix heavily influence the synchronized state. Finally, a chaotic neural network is used as the node in two regular networks to show the effectiveness of the proposed criteria. © 2006 IEEE.

Zhao Y.,Nanjing Southeast University | Zhao Y.,Harvard University | Zhao X.,Nanjing Southeast University | Gu Z.,Nanjing Southeast University | Gu Z.,Suzhou University
Advanced Functional Materials | Year: 2010

Photonic crystal (PC) based bioassay techniques have many advantages in sensitive biomolecular screening, label-free detection, real-time monitoring of enzyme activity, cell morphology research, and so on. This study provides an overall survey of the basic concepts and up-to-date research concerning the very promising use of PC materials for bioassays. It includes the design and application of PC films, PC microcarriers, PC fibers, and PC optofluidics for fluorescence enhancement or label-free bioassays. Emphasis is given to the description ofthe functional structures of different PC materials and their respective sensing mechanisms. Examples of detecting various types of analytes are presented. This article promotes communication among chemistry, biology, medicine, pharmacy, and material science. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.

Wang R.,Nanjing Southeast University | Zhang H.,Ohio State University | Wang J.,Ohio State University
IEEE Transactions on Control Systems Technology | Year: 2014

This paper presents a linear parameter-varying (LPV) control strategy to preserve stability and improve handling of a four-wheel independently actuated electric ground vehicle in spite of in-wheel motors and/or steering system faults. Different types of actuator faults including loss-of-effectiveness fault, additive fault, and the fault makes an actuator's control effect stuck-at-fixed-level, are considered simultaneously. To attenuate the effects of disturbance and address the challenging problem, a novel fault-tolerant (FT) robust linear quadratic regulator (LQR)-based H∞ controller using the LPV method is proposed. With the LQR-based H∞ control, the tradeoff between the tracking performance and the control input energy is achieved, and the effect from the external disturbance to the controlled outputs is minimized. The eigenvalue positions of the system matrix of the closed-loop system are also incorporated to tradeoff between the control inputs and the transient responses. The vehicle states, including vehicle yaw rate, lateral and longitudinal velocities, are simultaneously controlled to track their respective references. Simulations for different fault types and various driving scenarios are carried out with a high-fidelity, CarSim®, full-vehicle model. Simulation results show the effectiveness of the proposed FT control approach. © 2013 IEEE.

Yang Y.,Nanjing Audit University | Yang Y.,Nanjing Southeast University | Wang Y.,Soochow University of China
Extremes | Year: 2013

Let the random vector (X,Y) follow a bivariate Sarmanov distribution, where X is real-valued and Y is nonnegative. In this paper we investigate the impact of such a dependence structure between X and Y on the tail behavior of their product Z = XY. When X has a regularly varying tail, we establish an asymptotic formula, which extends Breiman's theorem. Based on the obtained result, we consider a discrete-time insurance risk model with dependent insurance and financial risks, and derive the asymptotic and uniformly asymptotic behavior for the (in)finite-time ruin probabilities. © 2012 Springer Science+Business Media, LLC.

Wang Y.,Nanjing Southeast University | Wang Y.,Nanjing Xiaozhuang College | Cao J.,Nanjing Southeast University
Nonlinear Analysis: Real World Applications | Year: 2013

In the real world, many networks show community structure, i.e., clusters of nodes, which have a high density of links within the same cluster but a lower density of links between different clusters. In this paper, nonlinearly coupled networks with community structure and non-identical nodes and with time-varying delay are considered. By applying pinning control to a fraction of network nodes, and using a suitable Lyapunov function, we obtain some new and useful synchronization criteria, which guarantee that various clusters are synchronized independently. An example is presented to show the application of the criteria obtained in this paper. © 2012 Published by Elsevier Ltd.

Li C.,University of Wisconsin - Madison | Li C.,Nanjing Southeast University | Sprott J.C.,University of Wisconsin - Madison
Nonlinear Dynamics | Year: 2013

A general approach based on the introduction of a control function for constructing amplitude-controllable chaotic systems with quadratic nonlinearities is discussed in this paper. We consider three control regimes where the control functions are applied to different coefficients of the quadratic terms in a dynamical system. The approach is illustrated using the Lorenz system as a typical example. It is proved that wherever control functions are introduced, the amplitude of the chaotic signals can be controlled without altering the Lyapunov exponent spectrum. © 2013 The Author(s).

Yang X.,Chongqing Normal University | Wu Z.,Chongqing Normal University | Cao J.,Nanjing Southeast University
Nonlinear Dynamics | Year: 2013

In this paper, we study the finite-time synchronization problem for linearly coupled complex networks with discontinuous nonidentical nodes. Firstly, new conditions for general discontinuous chaotic systems is proposed, which is easy to be verified. Secondly, a set of new controllers are designed such that the considered model can be finite-timely synchronized onto any target node with discontinuous functions. Based on a finite-time stability theorem for equations with discontinuous right-hand and inequality techniques, several sufficient conditions are obtained to ensure the synchronization goal. Results of this paper are general, and they extend and improve existing results on both continuous and discontinuous complex networks. Finally, numerical example, in which a BA scale-free network with discontinuous Sprott and Chua circuits is finite-timely synchronized onto discontinuous Chen system, is given to show the effectiveness of our new results. © 2013 Springer Science+Business Media Dordrecht.

Yang H.,Nanjing Southeast University | Ye G.,Tsinghua University | Wang X.,Tsinghua University | Keller P.,University Pierre and Marie Curie
Soft Matter | Year: 2011

Over the last few years, following a trend to miniaturization found in many fields of materials science, micron-sized liquid crystalline elastomer (LCE) actuators have been described, with the aim to apply them in such domains like responsive surfaces, microfluidic devices or microsensors. The preparations of the micron-sized LCE actuators involve plenty of cutting-edge, advanced technologies such as soft lithography, microfluidic, microprinting or photomasking. In this highlight, we describe the most striking results obtained in the domain of micron-sized LCE-based responsive systems. © 2011 The Royal Society of Chemistry.

Wang B.,Nanjing Southeast University | Qian Y.,Nanjing Southeast University
New Journal of Chemistry | Year: 2013

Two symmetrical donor-acceptor-donor chromophores built by connecting two triphenylamine donors to a central electron acceptor 2,5-diphenyl-1,3,4- oxadiazole or anthracene core have been synthesized and characterized. The aggregation-induced emission phenomenon of these compounds with bright and deep emission from orange to green in the solid state can be obsreved. The chromophores based on the triphenylamine unit exhibit efficient solid-state emission. The results indicate that D-A-D conjugation bridging provides a new opportunity for AIE-materials. The multiphoton induced fluorescence spectra of these chromophores were measured using a femtosecond Ti:sapphire. The three-photon excited fluorescence spectra are in the green region with peaks at 554 nm for An-BIPAS and 504 nm for Ox-BIASP in THF, respectively. These AIE-active compounds are potential materials to design sensitive and selective fluorescent sensors or bioprobes. © 2913 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

Zhao C.,Nanjing Southeast University | Chen X.,Nanjing Southeast University
Industrial and Engineering Chemistry Research | Year: 2012

The carbonation behaviors of K 2CO 3 generated by calcination of KHCO 3 were investigated with a pressurized thermo gravimetric apparatus, and the shrinking-core model in the noncatalytic heterogeneous reaction systems was used to explain the kinetics of the reaction between K 2CO 3, CO 2, and H 2O using analysis of the experimental breakthrough data. The carbonation reaction process can be divided into two stage-controlled regions, one is the surface chemical reaction-controlled region at the initial stage and another is the internal diffusion-controlled region at the last stage. The total amount of carbonation conversion is mainly dependent on the first stage. The reaction rate of this stage decreases as the reaction temperature increases. It increases in the same temperature when the CO 2 and H 2O concentrations increase. The total carbonation conversion decreases as the pressure increases. On the basis of the Arrhenius equation, the apparent activation energy and pre-exponential factor for these two stages are calculated, when the temperature is in the range of 55-80 °C and the pressure is 0.1 MPa. They are 33.4 kJ/mol and 3.56 cm/min for the surface chemical reaction-controlled region and 99.1 kJ/mol and 4.01 × 10 -22 cm 2/min for the internal diffusion-controlled region. This paper provides theoretical basis for the further study on the capture of CO 2 from flue gas using dry potassium-based sorbents. © 2012 American Chemical Society.

Zhao Y.,Nanjing Southeast University | Shang L.,Nanjing Southeast University | Cheng Y.,Nanjing Southeast University | Gu Z.,Nanjing Southeast University
Accounts of Chemical Research | Year: 2014

Colloidal photonic crystals (PhCs), periodically arranged monodisperse nanoparticles, have emerged as one of the most promising materials for light manipulation because of their photonic band gaps (PBGs), which a ffect photons in a manner similar to the effect of semiconductor energy band gaps on electrons. The PBGs arise due to the periodic modulation of the refractive index between the building nanoparticles and the surrounding medium in space with subwavelength period. This leads to light with certain wavelengths or frequencies located in the PBG being prohibited from propagating. Because of this special property, the fabrication and application of colloidal PhCs have attracted increasing interest from researchers. The most simple and economical method for fabrication of colloidal PhCs is the bottomup approach of nanoparticle self-assembly. Common colloidal PhCs from this approach in nature are gem opals, which are made from the ordered assembly and deposition of spherical silica nanoparticles after years of siliceous sedimentation and compression. Besides naturally occurring opals, a variety of manmade colloidal PhCs with thin film or bulk morphology have also been developed. In principle, because of the effect of Bragg diffraction, these PhC materials show different structural colors when observed from different angles, resulting in brilliant colors and important applications. However, this angle dependence is disadvantageous for the construction of some optical materials and devices in which wide viewing angles are desired. Recently, a series of colloidal PhC materials with spherical macroscopic morphology have been created. Because of their spherical symmetry, the PBGs of spherical colloidal PhCs are independent of rotation under illumination of the surface at a fixed incident angle of the light, broadening the perspective of their applications. Based on droplet templates containing colloidal nanoparticles, these spherical colloidal PhCs can be generated by evaporation-induced nanoparticle crystallization or polymerization of ordered nanoparticle crystallization arrays. In particular, because microfluidics was used for the generation of the droplet templates, the development of spherical colloidal PhCs has progressed significantly. These new strategies not only ensure monodispersity, but also increase the structural and functional diversity of the PhC beads, paving the way for the development of advanced optoelectronic devices. In this Account, we present the research progress on spherical colloidal PhCs, including their design, preparation, and potential applications. We outline various types of spherical colloidal PhCs, such as close-packed, non-close-packed, inverse opal, biphasic or multiphasic Janus structured, and core-shell structured geometries. Based on their unique optical properties, applications of the spherical colloidal PhCs for displays, sensors, barcodes, and cell culture microcarriers are presented. Future developments of the spherical colloidal PhC materials are also envisioned. (Figure Presented). © 2014 American Chemical Society.

Li X.,Nanjing Southeast University | Zhang W.,Nanjing Southeast University
IEEE Transactions on Vehicular Technology | Year: 2010

This paper presents a novel adaptive fault-tolerant multisensor navigation strategy for automated vehicles on the automated highway system. To ensure safe and reliable running, the main concern is how we can realize sensor fault detection, isolation, and accommodation. The proposed strategy adopts a hybrid decentralized filter architecture that fuses multiple sensors, including the strapdown inertial navigation system, the carrier phase-differential Global Positioning System (GPS), the wheel encoder, and the electronic compass. Through the integration of multiple redundancy sensors, the navigation system has fault-tolerant potential. The integrated filter model is first established in detail. Then, a highly fault-tolerant navigation filter iterative algorithm is proposed. The proposed algorithm realizes fault tolerance by utilizing fuzzy logic to update the local filter based on a relative degree of mismatch by simultaneously considering sensor failure degree and to make fault isolation decisions. To compare and evaluate the fault-tolerant performance, several traditional navigation methods are also investigated. Simulation results demonstrate that the proposed integrated navigation method can effectively detect, isolate, and accommodate a variety of hard and soft sensor failures, which may even simultaneously occur. © 2006 IEEE.

Al-Nuaimi M.K.T.,Nanjing Southeast University | Hong W.,Nanjing Southeast University
IEEE Antennas and Wireless Propagation Letters | Year: 2014

This letter presents the design and results of low-loss discrete dielectric flat reflectarray and lens for E-band. Using two different kinds of feed, 3-D-pyramidal (wideband) horn and 2×, 2 planar microstrip array (narrowband) antenna, the radiation performances of the two collimating structures are investigated. The discrete lens is optimized to cover the frequencies 71-86 GHz (71-76-and 81-86-GHz bands), while the discrete reflectarray is optimized to cover the 71-76-GHz band. The presented designs utilize the principle of perforated dielectric substrate using a square lattice of drilled holes of different radii and can be fabricated using standard printed circuit board (PCB) technology. The discrete lens has 41,×, 41 unit cells and thickness of 6.35 mm, while the reflectarray has 40,×,40 unit cells and thickness of 3.24 mm. A good impedance matching (S11\vert <-10 dB) and peak gain of 34 1dB with maximum aperture efficiency of 44.6% are achieved over 71-86 GHz for the lens case. On the other hand, reflectarray with peak gain of 32 1dB and aperture efficiency of 41.9% are achieved for 71-76-GHz band. © 2014 IEEE.

Gao C.,Nanjing Southeast University | Zhang L.,Nanjing Southeast University
Dianwang Jishu/Power System Technology | Year: 2011

Under vigorous promotion of government, electric vehicle (EV) industry in China gets into fast growth period, and it also greatly promotes the construction of charging facilities, namely charging stations and piles for EV, so the charging of lots of EV will greatly impact on power grid and the impacts vary with the popularization level of EV, EV types, charging time and charging mode of EV as well as the difference in charging modes and charging characteristics of EV. Based on present research status related to power grid connected to charging devices home and abroad and in the viewpoint of power transmission and distribution, the impact of EV charging on power grid is analyzed in detail. In allusion to the harmonic pollution in power grid caused EV charging stations, various measures to dispose harmonic pollution in power grid are presented, and it is pointed out that the future operation of power grid will be more and more impacted by charging behavior of EV and their energy storage characteristics, thus the research on siting planning for the construction of EV charging facilities and the control strategy for charging and discharging of EV will be the focus in this field.

Wang Z.Y.,Nanjing Southeast University
International journal of nanomedicine | Year: 2011

To explore the preparation and characterization of a novel nanosized magnetic liposome containing the PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex. Mn(0.5)Zn(0.5)Fe(2)O(4) and As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles were prepared by chemical coprecipitation and loaded with PEI. The PEI- As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex was characterized using transmission electron and scanning electron microscopy, X-ray diffraction, energy dispersive spectrometry, and Fourier transform infrared spectroscopy. Cell transfection experiments were performed to evaluate the transfect efficiency. Magnetic nanoliposomes were prepared by rotatory evaporation and their shape, diameter, and thermodynamic characteristics were observed. Mn(0.5)Zn(0.5)Fe(2)O(4) and PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles were spherical, with an average diameter of 20-40 nm. PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) was an appropriate carrier for the delivery of a foreign gene to HepG2 cells. Energy dispersive spectrometry results confirmed the presence of the elements nitrogen and arsenic. Nanoliposomes of approximately 100 nm were observed under a transmission electron microscope. Upon exposure to an alternating magnetic field, they also had good magnetic responsiveness, even though Mn(0.5)Zn(0.5)Fe(2)O(4)was modified by PEI and encased in liposomes. Temperatures increased to 37°C-54°C depending on different concentrations of PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4)and remained stable thereafter. Our results suggest that PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) magnetic nanoliposomes are an excellent biomaterial, which has multiple benefits in tumor thermotherapy, gene therapy, and chemotherapy.

Xu Z.,Nanjing Southeast University | Xu Z.,PLA University of Science and Technology
Applied Soft Computing Journal | Year: 2011

Interval fuzzy preference relations are an extension of fuzzy preference relations, which are usually used by experts to express their uncertain preference information over objects in group decision making. In this paper, we focus our attention on the investigation of consistency of interval fuzzy preference relations. We first establish a quadratic programming model by minimizing all the deviations of individual interval fuzzy preference relations and collective interval fuzzy preference relation, from which an exact solution can be found to derive the importance weights of experts. Then, we give two approaches to constructing additive and multiplicative consistent interval fuzzy preference relations, respectively, and show the relationship between the consistency of individual interval fuzzy preference relations and the consistency of collective interval fuzzy preference relation. At last, a practical application is given to our models and approaches. © 2011 Published by Elsevier B.V.

Xu Q.,Macau University of Science and Technology | Jia M.,Nanjing Southeast University
IEEE Transactions on Control Systems Technology | Year: 2014

This brief presents a scheme of model reference adaptive control with perturbation estimation (MRACPE) for precise motion control of a piezoelectric actuation micropositioning system. One advantage of the proposed scheme lies in the fact that the size of tracking error can be predesigned, which is desirable in practice. A second-order nominal system is assumed, and the unmodeled dynamics and nonlinearity effect are treated as a lumped perturbation, which is approximated by a perturbation estimation technique. A dead-zone modification of the adaptive rules is introduced to mitigate the parameter drifts and to speed up the parameter convergence. Moreover, the proposed MRACPE scheme employs the desired displacement trajectory rather than the voltage signal as the reference input. The stability of the closed-loop control system is proved through Lyapunov stability analysis. Experimental studies show that the MRACPE is superior to conventional proportional-integral-derivative control in terms of positioning accuracy for both set-point and sinusoidal positioning tasks, which is enabled by a significantly enlarged control bandwidth. © 2013 IEEE.

Guo Z.,University of North Carolina at Chapel Hill | Liu Q.,Nanjing Southeast University | Wang J.,Chinese University of Hong Kong
IEEE Transactions on Neural Networks | Year: 2011

In this paper, a one-layer recurrent neural network is presented for solving pseudoconvex optimization problems subject to linear equality constraints. The global convergence of the neural network can be guaranteed even though the objective function is pseudoconvex. The finite-time state convergence to the feasible region defined by the equality constraints is also proved. In addition, global exponential convergence is proved when the objective function is strongly pseudoconvex on the feasible region. Simulation results on illustrative examples and application on chemical process data reconciliation are provided to demonstrate the effectiveness and characteristics of the neural network. © 2011 IEEE.

Li M.,Nanjing Southeast University | Wu Z.,Nanjing Southeast University | Kao H.,Nanjing University of Technology
Applied Energy | Year: 2011

Fatty acid phase change materials (PCMs) have some advantages such as less corrosivity, no separation of subcooling phase and low price. In this paper, capric acid and palmitic acid are composited according to a certain mass ratio to prepare binary fatty acid. Capric-palmitic acid are absorbed into attapulgite by vacuum method to prepare capric-palmitic acid/attapulgite composite PCMs. Analysis methods such as differential scanning analysis (DSC), scanning electron microscope (SEM), Fourier transform infrared (FT-IR) and specific surface analysis (BET method) are used to test the thermal properties, structure and composition of the prepared composite PCM. The results indicate that the pore structure of the caplic-paltimic acid/attapulgite composite PCM is open-ended tubular capillary, which is beneficial to the adsorption. Capric acid and palmitic acid can be absorbed uniformly into attapulgite and the optimum absorption ratio of capric-palmitic binary fatty acid is 35%. There is no chemical reaction between the capric-palmitic acid and attapulgite. The phase change temperature of the capric-palmitic acid/attapulgite composite PCM is 21.71. °C and the latent heat is 48.2. J/g. © 2011 Elsevier Ltd.

Li M.,Nanjing Southeast University | Kao H.,Nanjing University of Technology | Wu Z.,Nanjing Southeast University | Tan J.,Nanjing Southeast University
Applied Energy | Year: 2011

This study prepared a series of binary phase change materials by mixing decanoic acid, dodecanoic acid, hexadecanoic acid. and octadecanoic acid each other. The phase-transition temperature of binary fatty acid and its corresponding mixing proportion are calculated with phase diagram thermodynamic method. The results are verified by the experimental result of the heat absorption curve and the Differential Scanning Calorimetry (DSC) analysis curve. The results show that the calculation method of phase diagram thermodynamic calculation can be taken as a basis for mixing proportion of binary fatty acid phase change materials. In addition, the decanoic-dodecanoic acid/diatomite composite phase change material (PCM) are prepared and its microstructure, thermal property and thermal. reliability. are characterized. The result shows that the decanoic-dodecanoic acid is uniformly adsorbed into diatomite and the form-stable PCM are formed. The phase-transition temperature and the latent heat of the decanoic-dodecanoic acid/diatomite composite PCMs is 16.74. °C and 66.8114 J/g, respectively. © 2010 Elsevier Ltd.

Xue H.,Nanjing Southeast University | Chen S.,Nanjing University of Aeronautics and Astronautics | Chen S.,Nanjing University | Yang Q.,Hong Kong University of Science and Technology
IEEE Transactions on Neural Networks | Year: 2011

Support vector machine (SVM), as one of the most popular classifiers, aims to find a hyperplane that can separate two classes of data with maximal margin. SVM classifiers are focused on achieving more separation between classes than exploiting the structures in the training data within classes. However, the structural information, as an implicit prior knowledge, has recently been found to be vital for designing a good classifier in different real-world problems. Accordingly, using as much prior structural information in data as possible to help improve the generalization ability of a classifier has yielded a class of effective structural large margin classifiers, such as the structured large margin machine (SLMM) and the Laplacian support vector machine (LapSVM). In this paper, we unify these classifiers into a common framework from the concept of structural granularity and the formulation for optimization problems. We exploit the quadratic programming (QP) and second-order cone programming (SOCP) methods, and derive a novel large margin classifier, we call the new classifier the structural regularized support vector machine (SRSVM). Unlike both SLMM at the cross of the cluster granularity and SOCP and LapSVM at the cross of the point granularity and QP, SRSVM is located at the cross of the cluster granularity and QP and thus follows the same optimization formulation as LapSVM to overcome large computational complexity and non-sparse solution in SLMM. In addition, it integrates the compactness within classes with the separability between classes simultaneously. Furthermore, it is possible to derive generalization bounds for these algorithms by using eigenvalue analysis of the kernel matrices. Experimental results demonstrate that SRSVM is often superior in classification and generalization performances to the state-of-the-art algorithms in the framework, both with the same and different structural granularities. © 2011 IEEE.

Yang L.,Nanjing Southeast University | Zhang X.,Nanjing Southeast University | Xu G.,Nanjing Southeast University
Energy and Buildings | Year: 2014

In this paper, a packed bed heat storage system using spherical capsules filled with three kinds of phase change material (PCM) was presented and numerically studied. The capsules are filled into a packed bed which is connected with a flat plate solar collector. The capsules are placed in series based on the melting temperature of PCM. Water is used as heat transfer fluid (HTF) and heated in the solar collector. Solar energy is transferred to PCM and preserved as latent thermal energy. The heat transfer processes of HTF and PCM capsules were modeled and numerically calculated by finite difference method. The effective thermal conductivity of liquid phase was used to take into account the effect of natural convection on heat transfer during melting. The energy and exergy performances of the multiple-type packed bed were studied and compared with the performances of single-type PCM packed bed. The performance of solar collector was also investigated. The comparison results indicate that this new type heat storage packed bed has higher energy and exergy transfer efficiencies than the traditional packed bed, and the average energy and exergy collection efficiency of its solar collector are higher too. © 2013 Elsevier B.V. All rights reserved.

Gai S.,Nanjing Southeast University | Gai S.,Huazhong University of Science and Technology | Da F.,Nanjing Southeast University
Optics Express | Year: 2010

A novel phase-analysis method is proposed. To get the fringe order of a fringe image, the amplitude-modulation fringe pattern is carried out, which is combined with the phase-shift method. The primary phase value is obtained by a phase-shift algorithm, and the fringe-order information is encoded in the amplitude-modulation fringe pattern. Different from other methods, the amplitude-modulation fringe identifies the fringe order by the amplitude of the fringe pattern. In an amplitudemodulation fringe pattern, each fringe has its own amplitude; thus, the order information is integrated in one fringe pattern, and the absolute fringe phase can be calculated correctly and quickly with the amplitude-modulation fringe image. The detailed algorithm is given, and the error analysis of this method is also discussed. Experimental results are presented by a full-field shape measurement system where the data has been processed using the proposed algorithm. © 2010 Optical Society of America.

Liu J.,Nanjing Southeast University
Advanced Materials Research | Year: 2012

The advantages of using asphalt rubber pavement strategies have been validated by many research efforts. However, the most obvious disadvantage of asphalt rubber hot mix is requiring a higher mix and placement temperature in order to obtain adequate workability, which results in higher energy requirements and asphalt easy ageing. By utilizing Warm Mix Asphalt(WMA) technology the temperature requirements of the asphalt rubber hot mix can be reduced significantly. Warm mix asphalt (WMA) is the name given to certain technologies that reduce the production and placement temperatures of asphalt mixes. Asphalt Rubber Hot Mix of containing Warm Mix technology is a very promising technology whether in energy saving or improving pavement performance. One of the main concentrations of crumb rubber mix is now on the moisture damage evaluation due to WMA additives. In this study, the objective was to conduct a laboratory investigation of moisture damage in Warm Rubber Mix Asphalt(WRMA). Currently, there are no standards or laboratory test data to support the knowledge area on the susceptibility of asphalt rubber mixtures to moisture damage. The widely accepted testing procedures i.e. indirect tensile strength (ITS) and tensile strength ratio (TSR) were performed to determine the moisture susceptibility of the mixtures. © (2012) Trans Tech Publications, Switzerland.

Li D.,Nanjing Southeast University | Chen Z.,Nanjing Southeast University
Experimental Thermal and Fluid Science | Year: 2014

The ultrasonic vibration is introduced to remove adherent frozen water droplets from cold surface, which provides the possibilities for effective defrosting. The shedding processes of various frozen water droplets adhered to 70. mm. ×. 70. mm cold vertical surface by 20. kHz and 60. W ultrasonic vibration were experimentally studied. It was found that the frozen water droplets instantaneously crack and shed off from the vertical surface due to the combined effects of interface transverse shear force generated by ultrasonic mechanical vibration and impact force induced by ultrasonic acoustic pressure. However, the heating effect triggered by ultrasonic vibration has limited effect on the frozen water droplets removal. Moreover, the frozen water droplets in different diameters within 2-30. mm can be successfully removed and all the frozen water droplets in different positions of 70. mm. ×. 70. mm cold surface can be completely shed off by 20. kHz high frequency ultrasonic vibration. The results showed that the ultrasonic vibration has a very strong ability to remove the frozen water droplets, which are the parasitic substrates for frosting, from cold flat surface and thus it is a highly potential defrosting method for practical application. © 2013 Elsevier Inc.

Cui B.,Nanjing Southeast University | Chen X.,Nanjing Southeast University
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2015

To approximate the complicated nonlinear relationship between temperature and FOG drift, a novel multi-scale modeling method is presented based on bounded ensemble empirical mode decomposition (BEEMD) and extreme learning machine (ELM)(designated as SE-BEEMD-ELM). Sample entropy (SE) is utilized to analyze all the intrinsic mode functions (IMF) produced by BEEMD, obtaining multiple sub-components of FOG drift by accumulating the IMFs according to the variation trend of SE values. Single ELM model is used time-dependent temperature gradients and sub-component as the input variables. Finally, all of the single models are combined to produce an ensemble model. Experiment result shows that compared with BEEMD-BP and BEEMD-ELM, which are based on the single model, the modeling accuracy of SE-BEEMD-ELM is improved by two orders. ©, 2015, Science Press. All right reserved.

Cao J.,Nanjing Southeast University | Song A.,Nanjing Southeast University
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2015

This paper proposes an improved texture image segmentation method based on Markov random field model. The fractional order differential algorithm is introduced in the image texture feature extraction process using its sensitivity to the complex image texture and edge details, and complete image texture detail is obtained. The proposed approach optimizes the description of the image texture features and overcomes the deficiency of insufficient image texture feature description in traditional methods. In order to segment the texture regions in the image precisely, the fuzzy entropy criteria is used to optimize the segmentation result and reduce the influence of noise interference and the local misjudgment. Experiment results on both natural and synthetic images show that the proposed method can extract complex image texture and edge details completely, effectively improve the segmentation accuracy and enhance the visual effects of the segmentation image. ©, 2015, Science Press. All right reserved.

Su H.,Nanjing Southeast University | Li Y.,Nanjing Southeast University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Based on complex network theory, a complex network model of power systems is proposed using quasi-steady power transfer distribution factor (PTDF), which can not only reflect the topological connection between components but also the actual power flow distribution. The component important can be analyzed with this model. Considering the efficiency for satisfying terminal load requirement of power systems, load loss rate is used to build the model of component vulnerability. The method of analyzing component vulnerability is presented with a program flowchart. Finally, results of IEEE case studies are used to verify the feasibility of the proposed model and the algorithm. © State Grid Electric Power Research Institute Press.

Wu G.,Nanjing Southeast University | Huang G.,Chinese Academy of Sciences | Ji H.,Chinese Academy of Sciences
Astrophysical Journal | Year: 2010

Anomalous resistivity is a critical parameter for triggering the fast magnetic reconnection and interpreting the eruption of solar flares in the nearly collisionless coronal plasma. However, the mechanism for the production of anomalous resistivity and its evolution are weakly understood. In this paper, the one-dimensional Vlasov equation was numerically solved with the typical solar coronal parameters and realistic mass ratio in the presence of strong inductive electric field, and the relationship between the anomalous resistivity and the reconnecting electric field was inferred for the area near the center of reconnecting current sheets. Our principal findings are summarized as follows. (1) The relationship between the anomalous resistivity and the reconnecting electric field E0 may be represented by ηeff = [10.82-10.99 exp(-0.36 E0)]Ω. m. (2) If E0 is small enough, it may be described by ηeff = [4.02 E0 - 0.18]Ω m, which is basically consistent with the early experimental results on the plasma response to the applied electric field. (3) In comparison with theoretical formulas for the current-driven ion-acoustic and Buneman anomalous resistivities, if E0 is small, the anomalous resistivity may be due to the ion-acoustic instability; if E0 is large, the anomalous resistivity may be due to the Buneman instability. These results are also basically consistent with early experiments. © 2010. The American Astronomical Society. All rights reserved. Printed in the U.S.A.

Wu W.,Nanjing Southeast University
Journal of Bridge Engineering | Year: 2014

Abstract A new type of bamboo composite I-shaped beam, which consists of bamboo laminate as its upper and down flange plates and bamboo curtain plywood as its web, was introduced in the paper. In this new type of beam, a connection between the flange plates and the web was enabled with a combined action of epoxy resin adhesive and a bolting joint. A model test on the bending mechanical properties (e.g., bending failure mode and bending capacity) and the factors influencing the flexural rigidity of the bamboo composite I-shaped beam was conducted. The preliminary results showed that the bamboo composite I-shaped beam has excellent mechanical properties that could offer high bending capacity and bending rigidity, as well as excellent ductility of the structure. Therefore, the bamboo composite I-shaped beam is potentially interesting for application in small- to medium-span bridges as a new type of structure. Moreover, this experimental research could help with a design method for bamboo composite I-shaped beams in the future. © 2013 American Society of Civil Engineers.

Yang W.,Nanjing Southeast University | Zhou J.,Nanjing Southeast University
IEEE Antennas and Wireless Propagation Letters | Year: 2014

A technique to design a wideband circularly polarized (CP) cavity-backed aperture antenna is presented in this letter. The proposed antenna consists of an aperture antenna, a low-profile backed cavity, and a parasitic patch. Bidirectional radiation of the aperture antenna is changed to unidirectional radiation using the low-profile backed cavity. The parasitic patch is adopted to provide a favorable axial-ratio (AR) bandwidth. The proposed antenna combines the attractive features such as wide impedance and AR bandwidths, compact size, high aperture efficiency, as well as easiness of design, manufacture, and integration. The antenna operates at 6-GHz band with the overall volume of 0.8 λ0× 0.8 λ0 × 0.3 λ0. Measured results show that the antenna achieves a 10-dB impedance bandwidth of more than 70% and a 3-dB AR bandwidth of 43.3% with a peak gain of 8.6 dBi. © 2002-2011 IEEE.

Yang T.Y.,Nanjing Southeast University | Hong W.,Nanjing Southeast University | Zhang Y.,Nanjing Southeast University
IEEE Antennas and Wireless Propagation Letters | Year: 2014

In this letter, a new type of wideband substrate integrated waveguide (SIW) cavity-backed patch antenna and array for millimeter wave (mmW) are investigated and implemented. The proposed antenna is composed of a rectangular patch with a backed SIW cavity. In order to enhance the bandwidth and radiation efficiency, the cavity is designed to resonate at its TE210 mode. Based on the proposed antenna, a 4×, 4 array is also designed. Both the proposed antenna and array are fabricated with standard printed circuit board (PCB) process, which possess the advantage of easy integration with planar circuits. The measured bandwidth (S11-10dB) of the antenna element is larger than 15%, and that of the antenna array is about 8.7%. The measured peak gains are 6.5 dBi for the element and 17.8 dBi for the array, and the corresponding simulated radiation efficiencies are 83.9% and 74.9%, respectively. The proposed antenna and array are promising for millimeter-wave applications due to its merits of wide band, high efficiency, low cost, low profile, etc. © 2002-2011 IEEE.

Wang J.,Nanjing Southeast University
International journal of nanomedicine | Year: 2011

A promising approach to optimize the disposition of daunorubicin-loaded magnetic nanoparticles (DNR-MNPs) was developed to minimize serious side effects of systematic chemotherapy for cancer. The physical properties of DNR-MNPs were investigated and their effect on leukemia cells in vitro was evaluated by a standard WST-1 cell proliferation assay. Furthermore, cell apoptosis and intracellular accumulation of DNR were determined by FACSCalibur flow cytometry. Our results showed that the majority of MNPs were spherical and their sizes were from 10 to 20 nm. The average hydrodynamic diameter of DNR-MNPs in water was 94 nm. The in vitro release data showed that the DNR-MNPs have excellent sustained release property. Proliferation of K562 cells was inhibited in a dose-dependent manner by DNR in solution (DNR-Sol) or by DNR-MNPs. The IC(50) for DNR-MNPs was slightly higher than that for DNR-Sol. DNR-MNPs also induced less apoptosis in K562 cells than did DNR-Sol. Detection of fluorescence intensity of intracellular DNR demonstrated that DNR-MNPs could be taken up by K562 cells and persistently released DNR in cells. Our study suggests that optimized DNR-MNPs formulation possesses sustained drug-release and favorable antitumor properties, which may be used as a conventional dosage form for antitumor therapy.

Zhang Q.,Nanjing Southeast University | Su M.,Nanjing Southeast University | Lu G.,Nanjing University | Wang J.,Nanjing University
Molecular Cancer | Year: 2013

The mammalian genome encodes thousands of long noncoding RNAs (lncRNAs) and it is increasingly clear that lncRNAs are key regulators of cellular function and development. Gain and/or loss of function studies in cell culture indicate that lncRNAs can regulate gene transcription indirectly through the targeting and recruitment of chromatin-modifying complexes as well as directly at the transcriptional or posttranscriptional levels. LncRNA biology is attracting great attention in cancer research because dysregulated lncRNAs occur in a variety of cancers, placing lncRNAs on the stage of cancer genome research. We briefly describe the latest lncRNA biology and discuss the oncogenic lncRNAs involved in core pathways in bladder cancer and the application of lncRNAs to its diagnosis and targeted treatment. LncRNAs are becoming essential components of the gene regulatory circuitry in the complexity of bladder cancer. © 2013 Zhang et al.; licensee BioMed Central Ltd.

Zou Z.,Nanjing Southeast University | Wang Z.,Nanjing Southeast University | Cheng M.,Nanjing Southeast University
IEEE Transactions on Power Electronics | Year: 2014

The purpose of this paper is to investigate the model, control, and implementation of a multifunction grid-interfaced inverter with output LCL filter, which can provide high performance active power current and compensate the existent harmonics simultaneously in a distributed network. Equipped with LCL filter, the proposed multifunction inverter offers reduced switching harmonics and superior output current shapes. However, the multifunction inverter with output LCL filter brings some challenges, including LCL resonance, phase lag, and complexity in system design. To address these issues, this paper analyzes and develops general Thevenin/Norton models for the multifunction grid inverters with LCL filter. Based on the general models of system, this paper presents guidelines of the control and the procedure of filter design for this application. In particular, a proportional-resonant (PR) plus odd-harmonic repetitive control (OHRC) scheme is designed for the outer current loop. The phase compensation method and detailed design criteria for the proposed control scheme are presented. Furthermore, the proposed OHRC scheme is compared with the previous multiple resonant control (MRC) based on their internal relationship. Simulation and experimental results are provided to validate the effectiveness and advantages of the proposed control strategy. © 1986-2012 IEEE.

Du H.,Hefei University of Technology | Du H.,Nanjing Southeast University | Li S.,Nanjing Southeast University
Automatica | Year: 2014

To solve the problem of attitude synchronization for a group of flexible spacecraft during formation maneuvers, a distributed attitude cooperative control strategy is investigated in this paper. Based on the backstepping design and the neighbor-based design rule, a distributed attitude control law is constructed step by step. Using cascaded systems' theory and graph theory, it is shown that the attitude synchronization is achieved asymptotically and the induced vibrations by flexible appendages are simultaneously suppressed under the proposed control law. © 2013 Elsevier Ltd. All rights reserved.

Wu Y.,Nanjing Southeast University | Wei W.,Nanjing Southeast University | Liu S.,Nanjing Southeast University
Accounts of Chemical Research | Year: 2012

Because of the potential applications of biosensors in clini- cal diagnosis, biomedical research, environmental analysis, and food quality control, researchers are very interested in developing sensitive, selective, rapid, reliable, and low-cost versions of these devices. A classic biosensor directly transduces ligand-target binding events into a measurable physical readout. Because of the limited detection sensitivity and selectivity in earlier biosensors, researchers have developed a number of sensing/signal amplification strategies. Through the use of nanostructured or long chain polymeric materials to increase the upload of signal tags for amplification of the signal readout associated with the ligand-target binding events, researchers have achieved high sensitivity and exceptional selectivity.Very recently, target-triggered polymerization-assisted signal amplification strategies have been exploited as a new biosensing mechanism with many attractive features. This strategy couples a small initiator molecule to the DNA/protein detection probe prior to DNA hybridization or DNA/protein and protein/protein binding events. After ligand-target binding, the in-situ polymerization reaction is triggered. As a result, tens to hundreds of small monomer signal reporter molecules assemble into long chain polymers at the location where the initiator molecule was attached. The resulting polymer materials changed the optical and electrochemical properties at this location, which make the signal easily distinguishable from the background. The assay time ranged from minutes to hours and was determined by the degree of amplification needed.In this Account, we summarize a series of electrochemical and optical biosensors that employ target-triggered polymerization. We focus on the use of atom transfer radical polymerization (ATRP), as well as activator generated electron transfer for atom transfer radical polymerization (AGET ATRP) for in-situ formation of polymer materials for optically or electrochemically transducing DNA hybridization and protein-target binding. ATRP and AGET ATRP can tolerate a wide range of functional monomers. They also allow for the preparation of well-controlled polymers with narrow molecular weight distribution, which was predetermined by the concentration ratio of the consumed monomer to the introduced initiator.Because the reaction initiator can be attached to a variety of detection probes through well-established cross-linking reactions, this technique could be expanded as a universal strategy for the sensitive detection of DNA and proteins. We see enormous potential for this new sensing technology in the development of portable DNA/protein sensors for point-of-need applications. © 2012 American Chemical Society.

Gambogic acid (GA), a potent anticancer agent, is limited in clinical administration due to its poor water solubility. The aim of this study was to explore a drug delivery system based on magnetic Fe(3)O(4) nanoparticles (MNP-Fe(3)O(4)) conjugated with GA to increase water solubility of the drug and enhance its chemotherapeutic efficiency for pancreatic cancer. GA was conjugated with the MNP-Fe(3)O(4) colloidal suspension by mechanical absorption polymerization to construct GA-loaded MNP-Fe(3)O(4), which acted as a drug delivery system. Combination therapy with GA and MNP-Fe(3)O(4) induced remarkable improvement in anticancer activity, which was demonstrated by optical microscopic observations, MTT assay, and nuclear DAPI staining. Furthermore, the possible signaling pathway was explored by Western blot. In Capan-1 pancreatic cancer cells, our observations demonstrated that this strategy could enhance potential anticancer efficiency by inducing apoptosis. The mechanisms of the synergistic effect may be due to reducing protein expression of Bcl-2 and enhancing that of Bax, caspase 9, and caspase 3. These findings demonstrate that a combination of GA and MNPs-Fe(3)O(4) represents a promising approach to the treatment of pancreatic cancer.

This study aims to evaluate the potential benefit of combination therapy of 2-methoxyestradiol (2ME) and magnetic nanoparticles of Fe(3)O(4) (MNPs-Fe(3)O(4)) on myelodysplastic syndrome (MDS) SKM-1 cells and its underlying mechanisms. The effect of the unique properties of tetraheptylammonium-capped MNPs-Fe(3)O(4) with 2ME on cytotoxicity was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell-cycle distribution and apoptosis were assessed by flow cytometry. The expression of cell-cycle marker protein was measured by Western blotting. Growth inhibition rate of SKM-1 cells treated with the 2ME-loaded MNPs-Fe(3)O(4) was enhanced when compared with 2ME alone. 2ME led to an increase of caspase-3 expression, followed by apoptosis, which was significantly increased when combined with an MNPs-Fe(3)O(4) carrier. Moreover, the copolymer of 2ME with MNPs- Fe(3)O(4) blocked a nearly two-fold increase in SKM-1 cells located in G(2)/M phase than in 2ME alone, which may be associated with an accompanying increase of p21 as well as a decrease in cyclin B1 and cdc2 expression, but there was no obvious difference between the MNPs-Fe(3)O(4) and control group. These findings suggest that the unique properties of MNPs-Fe(3)O(4) as a carrier for 2ME, a new anticancer agent currently in clinical trials, may be a logical strategy to enhance the therapeutic activity of MDS.

Wang C.,Nanjing Southeast University | Li J.,Nanjing Southeast University | Amatore C.,CNRS PASTEUR Laboratory | Chen Y.,East China University of Science and Technology | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

Gold and carbon make it together: Gold nanoclusters (GNCs) impregnated onto reduced graphene oxide (RGO) nanosheets cross swiftly across HepG2 hepatocarcinoma cell membranes to alter proteins and DNA and transport anticancer molecular drugs, such as doxorubicin (DOX). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cheng J.,Nanjing Southeast University
International journal of nanomedicine | Year: 2011

To overcome both the dose-limiting side effects of conventional chemotherapeutic agents and the therapeutic failure resulting from multidrug resistance (MDR) and minimize adverse effects of chemotherapy agents, a novel chemotherapy formulation of magnetic nanoparticles co-loaded with daunorubicin and 5-bromotetrandrin (DNR/BrTet-MNPs) was developed, and its effect on MDR leukemic cells was explored. After the DNR and Br were co-loaded onto a pluronic-stabilized and oleic acid-modified magnetic nanosystem, the physical characteristic and drug-loading capacity were evaluated. The cell toxicity of the self-prepared DNR/BrTet-MNPs formulation was then determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay; the cellular uptake of drug was demonstrated by fluorescent microscope. Lastly, the transcription of mdr1 and the expression of P-glycoprotein (P-gp) were detected by the reverse transcription reaction and western blotting assay, respectively. The results showed that the self-prepared DNR/BrTet-MNPs formulation possessed a sustained release of drug and displayed a dose-dependent antiproliferative activity on MDR leukemia K562/A02 cells. It also enhanced the accumulation of intracellular DNR in K562/A02 cells and downregulated the transcription of the mdr1 gene and the expression of P-gp. These findings suggest that the remarkable effect of the novel DNR/BrTet-MNPs formulation, acting as a drug depot system for the sustained release of the loaded DNR and BrTet, on multidrug resistance leukemia K562/A02 cells would be a promising strategy for overcoming MDR.

The purpose of this study was to develop intraperitoneal hyperthermic therapy based on magnetic fluid hyperthermia, nanoparticle-wrapped cisplatin chemotherapy, and magnetic particles of albumin. In addition, to combine the multiple-killing effects of hyperthermal targeting therapy, chemotherapy, and radiotherapy, the albumin-nanoparticle surfaces were linked with radionuclide (188)Re-labeled folic acid ligand ((188)Re-folate-CDDP/HSA). Human serum albumin was labeled with (188)Re using the pre-tin method. Reaction time and optimal conditions of labeling were investigated. The particles were intravenously injected into mice, which were sacrificed at different time points. Radioactivity per gram of tissue of percent injected dose (% ID/g) was measured in vital organs. The biodistribution of (188)Re-folate-CDDP/HAS magnetic nanoparticles was assessed. Optimal conditions for (188)Re-labeled folate-conjugated albumin combined with cisplatin magnetic nanoparticles were: 0.1 mL of sodium gluconate solution (0.3 mol/L), 0.1 mL of concentrated hydrochloric acid with dissolved stannous chloride (10 mg/mL), 0.04 mL of acetic acid buffer solution (pH 5, 0.2 mol/L), 30 mg of folate-conjugated albumin combined with cisplatin magnetic nanoparticles, and (188)ReO(4) eluent (0.1 mL). The rate of (188)Re-folate-CDDP-HSA magnetic nanoparticle formation exceeded 90%, and radiochemical purity exceeded 95%. The overall labeling rate was 83% in calf serum at 37°C. The major uptake tissues were the liver, kidney, intestine, and tumor after the (188)Re-folate-CDDP/HSA magnetic nanoparticles were injected into nude mice. Uptake of (188)Re-folate-CDDP/HSA magnetic nanoparticles increased gradually after injection, peaked at 8 hours with a value of 8.83 ± 1.71, and slowly decreased over 24 hours in vivo. These results indicate that (188)Re-folate-CDDP/HSA magnetic nanoparticles can be used in radionuclide-targeted cancer therapy. Surface-modified albumin nanoparticles with folic acid ligand-labeled radionuclide ((188)Re) were successfully prepared, laying the foundation for a triple-killing effect of thermotherapy, chemotherapy, and radiation therapy.

Zheng W.-N.,Nanjing Southeast University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

In the title compound, (C6H14N2)[Mg(H 2O)6](SO4)2, the MgII ion, lying on an inversion center, is coordinated by six water molecules in a slightly distorted octahedral geometry. The 1,4-diazoniabicyclo[2.2.2]octane cation is located about a twofold rotation axis. Intermolecular N - H⋯O and O - H⋯O hydrogen bonds link the cations and the anions into a three-dimensional network.

Zhu R.-Q.,Nanjing Southeast University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

In the crystal structure of the title compound, C7H 15ClN22+·2PF6-, the cations and anions are linked by intermolecular N -H⋯F hydrogen bonds.

Xu H.,Nanjing Southeast University | Zheng J.,Nankai University
Macromolecular Chemistry and Physics | Year: 2010

A general approach to construct one-dimensional face-to-face alignment of porphyrin/fullerene nanowires has been developed. This system uses extended trans-dihydroxotin(IV) porphyrin and trans-dicarboxylate-substituted [60]fullerenoacetic diacid compounds. The nanowires are arranged in regular one-dimensional linear arrays with lengths in the range 50-300 nm. In the nanowires, each fullerene unit is axially coordinated to the central metal ion of a Sn(IV) porphyrin unit via Sn-carboxylate coordination and forms a face-to-face aligned structure. The synthesis and the hierarchical structure of nanowires have been investigated. They could have potential applications for photoelectronic devices, organic solar cells and so on. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhang M.-L.,Nanjing Southeast University | Zhang M.-L.,Nanjing University | Zhang K.,Max Planck Institute for Biological Cybernetics
Proceedings of the ACM SIGKDD International Conference on Knowledge Discovery and Data Mining | Year: 2010

In multi-label learning, each training example is associated with a set of labels and the task is to predict the proper label set for the unseen example. Due to the tremendous (exponential) number of possible label sets, the task of learning from multi-label examples is rather challenging. Therefore, the key to successful multi-label learning is how to effectively exploit correlations between different labels to facilitate the learning process. In this paper, we propose to use a Bayesian network structure to efficiently encode the conditional dependencies of the labels as well as the feature set, with the feature set as the common parent of all labels. To make it practical, we give an approximate yet efficient procedure to find such a network structure. With the help of this network, multi-label learning is decomposed into a series of single-label classification problems, where a classifier is constructed for each label by incorporating its parental labels as additional features. Label sets of unseen examples are predicted recursively according to the label ordering given by the network. Extensive experiments on a broad range of data sets validate the effectiveness of our approach against other well-established methods. © 2010 ACM.

Qian J.,Nanjing Southeast University | Zhang C.,Nanjing Southeast University | Cao X.,Nanjing Southeast University | Liu S.,Nanjing Southeast University
Analytical Chemistry | Year: 2010

A versatile immunosensor using a CdTe quantum dots (QDs) coated silica nanosphere (Si/QD) as a label was proposed for ultrasensitive detection of a biomarker. In this approach, silica nanospheres with good monodispersity and uniform structure were employed as the carrier for immobilization of QDs and antibodies. Rabit IgG served as a model protein to demonstrate the performance of the immunosensor. Goat antirabbit IgG antibody was covalently bound to CdTe QDs on the surface of silica nanospheres. CdTe QDs coated with a silica nanosphere label (Si/QD/Ab2) were attached onto the gold electrode surface through a subsequent "sandwich" immunoreaction. This reaction was confirmed by scanning electron microscopic (SEM) and fluorescence microscopic images. Due to signal amplification from the high loading of CdTe QDs, 6.6- and 5.9-fold enhancements in electrochemiluminescent (ECL) and square-wave voltammetric (SWV) signals for IgG detection were achieved compared to the unamplified method. The detection limits for IgG were 1.3 and 0.6 pg mL -1 for ECL and SWV measurements, respectively. The resulting versatile immunosensor possesses high sensitivity, satisfactory reproducibility and regeneration, and good precision. This simple and specific strategy has vast potential to be used in other biological assays. © 2010 American Chemical Society.

Ding Z.,Newcastle University | Ma Z.,Southwest Jiaotong University | Ma Z.,Nanjing Southeast University | Fan P.,Southwest Jiaotong University
IEEE Transactions on Wireless Communications | Year: 2014

In this paper, we consider a two-way relaying scenario with one pair of source nodes, one relay and one eavesdropper. All nodes are equipped with multiple antennas, and we study the impact of antenna selection on such a secure communication scenario. Three transmission schemes with different tradeoff between secure performance and complexity are investigated respectively. Particularly, when antenna selection is implemented at the relay and no artificial noise is introduced, the condition to realize secure transmissions is established. Then by allowing the sources to inject artificial noise into the system, the secure performance is evaluated by focusing on different eavesdropping strategies. When both the relay and the sources send artificial noise, a low complexity strategy of antenna selection is proposed to efficiently utilize the antennas at the sources and the relay. The developed asymptotic results demonstrate that, by adding more artificial noise and performing joint antenna selection, a better secure performance, such as a larger secrecy rate and a lower outage probability, can be realized at a price of imposing more complexity on the system. Simulation results are also provided to demonstrate the accuracy of the developed analytical results. © 2002-2012 IEEE.

Yang J.,Nanjing Southeast University | Su J.,Loughborough University | Li S.,Nanjing Southeast University | Yu X.,RMIT University
IEEE Transactions on Industrial Informatics | Year: 2014

A new continuous dynamic sliding-mode control (CDSMC) method is proposed for high-order mismatched disturbance attenuation in motion control systems using a high-order sliding-mode differentiator. First, a new dynamic sliding surface is developed by incorporating the information of the estimates of disturbances and their high-order derivatives. A CDSMC law is then designed for a general motion control system with both high-order matched and mismatched disturbances, which can attenuate the effects of disturbances from the system output. The proposed control method is finally applied for the airgap control of a MAGnetic LEViation (MAGLEV) suspension vehicle. Simulation results show that the proposed method exhibits promising control performance in the presence of high-order matched and mismatched disturbances. © 2005-2012 IEEE.

Yan L.,Nanjing Southeast University | Yang F.,Hohai University
Engineering Analysis with Boundary Elements | Year: 2013

In this paper, an efficient Kansa-type method of fundamental solutions (MFS-K) is extended to the solution of two-dimensional time fractional sub-diffusion equations. To solve initial boundary value problems for these equations, the time dependence is removed by time differencing, which converts the original problems into a sequence of boundary value problems for inhomogeneous Helmholtz-type equations. The solution of this type of elliptic boundary value problems can be approximated by fundamental solutions of the Helmholtz operator with different test frequencies. Numerical results are presented for several examples with regular and irregular geometries. The numerical verification shows that the proposed numerical scheme is accurate and computationally efficient for solving two-dimensional fractional sub-diffusion equations. © 2013 Elsevier Ltd.

Liang H.,Nanjing Southeast University | Xu Z.,Nanjing Southeast University | Si F.,Nanjing Southeast University
International Journal of Greenhouse Gas Control | Year: 2011

Post-combustion CO 2 capture and storage is among the most mature technologies to capture, compress, transport and store CO 2 from flue gas in coal-fired power plant. This paper presents the simulation of monoethanolamine (MEA) based CO 2 capture and compression process integrated within a 600MW e supercritical coal-fired power plant using chemical process simulators. Comparison between bi-pressure stripper and single-pressure stripper reveals that improved CO 2 capture system with bi-pressure stripper minimizes energy penalty of CO 2 capture and compression by up to 6.3% at full unit load. The study also explores optimization of some important process parameters affecting the performance of coal-fired power plant by taking into account both CO 2 capture process and CO 2 compression at full unit load. These parameters include operating stripper pressure, CO 2 capture efficiency and steam extraction location. Results show that the optimal stripper pressure is within the range of 1.9-2.1bar and feasible CO 2 capture efficiency is between 60% and 90%. Results also show that low-pressure steam extraction reduces energy penalty. Evaluation of improved CO 2 capture system is also performed at part flue gas load ranging from 40% to 90%. The study reveals that operating at part flue gas load, as compared with full load, increases energy penalty of carbon capture. Not only energy penalty but also lean solution flow rate and plant efficiency are studied at different flue load levels in this paper. In addition, results show that bi-pressure stripper configuration is also effective in reducing energy penalty at part unit load. © 2011 Elsevier Ltd.

An Y.L.,Nanjing Southeast University
International journal of nanomedicine | Year: 2011

Our objective was to prepare a new nano-sized realgar particle and characterize its anti-tumor effect on tumor cells. Nanoparticles were prepared by coprecipitation and were detected by transmission electron microscopy, scanning electron microscopy, energy dispersive spectrometry (EDS), and dynamic light scattering. An anti-proliferative effect of realgar nanoparticles on rat glioma (C6) cells was determined by the MTT assay. Cell cycle and apoptosis rates were observed by flow cytometry. Apoptosis-related gene expression was detected by immunofluorescence staining. Realgar nanoparticles were successfully prepared. The particles were spherical, with an average diameter of approximately 80 nm, and contained arsenic and sulfur elements. Realgar nanoparticles inhibited C6 cell proliferation and induced apoptosis in a dose- and time-dependent manner. Treatment of C6 cells with realgar nanoparticles significantly increased the proportions of cells in S and G2/M phases, decreased the proportion of cells in G0/G1 phase, downregulated Bcl-2 expression, and substantially upregulated Bax expression. Realgar nanoparticles significantly inhibited C6 glioma cell proliferation and promoted cell apoptosis by inducing the upregulation of Bax and downregulation of Bcl-2 expression. Realgar nanoparticles are a promising in vitro anti-cancer strategy and may be applicable for human cancer therapy studies.

This paper presents a discussion on a recent article authored by Pichler et al. [Differential-scheme based dissolution diffusion model for calcium leaching in cement-based materials accounting for mix design and binder composition, Cem. Concr. Res. 42 (2012) 686-699]. © 2014 Elsevier Ltd.

Zheng W.,Nanjing Southeast University
IEEE Transactions on Affective Computing | Year: 2014

In this paper, a novel multi-view facial expression recognition method is presented. Different from most of the facial expression methods that use one view of facial feature vectors in the expression recognition, we synthesize multi-view facial feature vectors and combine them to this goal. In the facial feature extraction, we use the grids with multi-scale sizes to partition each facial image into a set of sub regions and carry out the feature extraction in each sub region. To deal with the prediction of expressions, we propose a novel group sparse reduced-rank regression (GSRRR) model to describe the relationship between the multi-view facial feature vectors and the corresponding expression class label vectors. The group sparsity of GSRRR enables us to automatically select the optimal sub regions of a face that contribute most to the expression recognition. To solve the optimization problem of GSRRR, we propose an efficient algorithm using inexact augmented Lagrangian multiplier (ALM) approach. Finally, we conduct extensive experiments on both BU-3DFE and Multi-PIE facial expression databases to evaluate the recognition performance of the proposed method. The experimental results confirm better recognition performance of the proposed method compared with the state of the art methods. © 2014 IEEE.

Xu H.-Y.,Peking Union Medical College | Gu N.,Nanjing Southeast University
Frontiers of Materials Science | Year: 2014

Increasing evidence shows that magnetic fields and magnetic responsive scaffolds can play unique roles in promoting bone repair and regeneration. This article addresses the synergistic effects of magnetic scaffolds in response to external magnetic fields on the bone regeneration in situ. Additionally, the exploration of using magnetic scaffolds as tools in the bone implant fixation, local drug delivery and mimicking microenvironment of stem cell differentiation are introduced. We also discussed possible underlying mechanisms and perspectives of magnetic responsive scaffolds in the bone repair and regeneration. © 2014 Higher Education Press and Springer-Verlag Berlin Heidelberg.

Xu F.,Nanjing Southeast University | Wang X.,Nanjing Southeast University | Wang L.,Nanjing Southeast University
Journal of Field Robotics | Year: 2011

As the most important component of cable-stayed bridges, cable safety has been of crucial public concern. In this paper, a new robot system for the inspection of stay cables is proposed. The robot not only replaces human workers in carrying out risky tasks in a hazardous environment but also increases operational efficiency by eliminating costly erection of scaffolding or dragging of winches. The designed robot is composed of two equally spaced modules, joined by connecting bars to form a closed hexagonal body that clasps the cable. For safe landing in case of an electrical interruption or malfunction, a gas damper with a slider-crank mechanism is proposed to use up the extra energy generated by gravity when the robot slips down. To conserve energy, a landing method based on back electromotive force is introduced. Laboratory and field experiments verified that the robot can stably climb random inclined cables and land smoothly upon electrical malfunction. Finally, along with an application example, the vision inspection system based on charge-coupled device cameras, operating modes of the robot, control methods, and feasibility are discussed in detail. The field applications on two cable-stayed bridges indicate that such a low-cost robot system can improve the efficiency of inspection operations and satisfy the requirements of actual cable inspection. Copyright © 2011 Wiley Periodicals, Inc.

Wu Q.,Nanjing Southeast University
Expert Systems with Applications | Year: 2011

In view of the shortage of -insensitive loss function for hybrid noises such as singularity points, biggish magnitude noises and Gaussian noises, this paper presents a new version of fuzzy support vector machine (SVM) which can penalize those hybrid noises to forecast fuzzy nonlinear system. Since there exist some problems of hybrid noises and uncertain data in many actual forecasting problem, the input variables are described as fuzzy numbers by fuzzy comprehensive evaluation. Then by the integration of the triangular fuzzy theory, ν-SVM and loss function theory, the fuzzy robust ν-SVM with robust loss function (FRν-SVM) which can penalize those hybrid noises is proposed. To seek the optimal parameters of FRν-SVM, particle swarm optimization is also proposed to optimize the unknown parameters of FRν-SVM. The results of the application in fuzzy sale system forecasts confirm the feasibility and the validity of the FRν-SVM model. Compared with the traditional model and other SVM methods, FRν-SVM method requires fewer samples and has better generalization capability for Gaussian noise. © 2010 Elsevier Ltd. All rights reserved.

Cheng M.,Nanjing Southeast University | Zhu Y.,Nanjing Southeast University
Energy Conversion and Management | Year: 2014

This paper gives a comprehensive review of the state of the art of wind energy conversion systems (WECS) and technologies, with an emphasis on wind power generator and control. First, different types of common WECSs are classified according to their features and drive train types. The WECSs are compared on the basis of the volume, weight, cost, efficiency, system reliability and fault ride through capability. The maximum power point tracking (MPPT) control, which aims to make the generator speed meet an optimum value to ensure the maximum energy yield, plays a key role in the variable speed WECSs. A comprehensive review and comparison of the four most popular MPPT control methods are carried out and improvements for each method are presented. Furthermore, the latest development of wind energy conversion technologies is introduced, such as the brushless doubly fed induction generator (BDFIG), the stator permanent magnet synchronous generators, the magnetic-geared generators, dual power flow WECS with the electrical variable transmission (EVT) machine, and direct grid-connected WECS. Finally, the future trends of the technologies are discussed. © 2014 Elsevier Ltd. All rights reserved.

Zhang M.-L.,Nanjing Southeast University | Zhou Z.-H.,Nanjing University
IEEE Transactions on Knowledge and Data Engineering | Year: 2014

Multi-label learning studies the problem where each example is represented by a single instance while associated with a set of labels simultaneously. During the past decade, significant amount of progresses have been made toward this emerging machine learning paradigm. This paper aims to provide a timely review on this area with emphasis on state-of-the-art multi-label learning algorithms. Firstly, fundamentals on multi-label learning including formal definition and evaluation metrics are given. Secondly and primarily, eight representative multi-label learning algorithms are scrutinized under common notations with relevant analyses and discussions. Thirdly, several related learning settings are briefly summarized. As a conclusion, online resources and open research problems on multi-label learning are outlined for reference purposes. © 1989-2012 IEEE.

Zhang G.-H.,Nanjing Southeast University | Jiang W.-Z.,Nanjing Southeast University | Jiang W.-Z.,National Laboratory of Heavy Ion Accelerator
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

The liquid-gas phase transition in hot asymmetric nuclear matter is studied within density-dependent relativistic mean-field models where the density dependence is introduced according to the Brown-Rho scaling and constrained by available data at low densities and empirical properties of nuclear matter. The critical temperature of the liquid-gas phase transition is obtained to be 15.7 MeV in symmetric nuclear matter falling on the lower edge of the small experimental error bars. In hot asymmetric matter, the boundary of the phase-coexistence region is found to be sensitive to the density dependence of the symmetry energy. The critical pressure and the area of phase-coexistence region increases clearly with the softening of the symmetry energy. The critical temperature of hot asymmetric matter separating the single-phase region from the two-phase region is analyzed to have a moderate sensitivity to the symmetry energy and is higher for the model possessing the softer symmetry energy. © 2013.

Zhao S.,Nanjing Southeast University | Fan J.,Nanjing Southeast University | Sun W.,Nanjing Southeast University
Construction and Building Materials | Year: 2014

Iron ore tailings are a common type of hazardous solid waste in China and have caused serious environmental problems, and the high cost of producing ultra-high performance concrete (UHPC) provides the motivation to look for low-priced raw materials. In this paper, the possibility of using iron ore tailings to replace natural aggregate to prepare UHPC under two different curing regimes was investigated. It was found that 100% replacement of natural aggregate by the tailings significantly decreased the workability and compressive strength of the material. However, when the replacement level was no more than 40%, for 90 days standard cured specimens, the mechanical behavior of the tailings mixes was comparable to that of the control mix, and for specimens that were steam cured for 2 days, the compressive strengths of the tailings mixes decreased by less than 11% while the flexural strengths increased by up to 8% compared to the control mix. In addition, pore structure analysis revealed a coarsening of micro-pore structure with an increase of the tailings content and a good correlation between the porosities and compressive strengths of the UHPC matrices, and microstructure image showed a possibly poor interfacial transition zone around some tailings particles. © 2013 Elsevier Ltd. All rights reserved.

Zhang Z.,Nanjing Southeast University | Li S.,Nanjing Southeast University | Luo S.,Luoyang Optoelectro Technology Development Center
Transactions of the Institute of Measurement and Control | Year: 2013

For the terminal phase of tactical missiles intercepting maneuvering targets, the terminal guidance problem is studied. Based on an integral sliding mode (ISM) control method and nonlinear disturbance observer technique, a novel composite guidance law is designed in the case of constrained impact angle and a first-order-lag autopilot. Regarding the target acceleration and the external disturbance of autopilot as unknown bounded disturbance, a nonlinear ISM guidance law is designed. The obtained guidance law guarantees the line-of-sight (LOS) angular rate and LOS angle a finite-time convergence characteristics. Then, to alleviate the chattering problem and guarantee the disturbance rejection performance, the composite guidance law combining the ISM guidance law with feedforward compensation terms based on nonlinear disturbance observers is obtained. Finally, simulation comparison results are provided to demonstrate the effectiveness of the presented methods. © The Author(s) 2013.

Zhao S.,Nanjing Southeast University | Sun W.,Nanjing Southeast University
Construction and Building Materials | Year: 2014

As a revolutionary construction material, ultra-high performance concrete (UHPC) has been extensively studied in the last two decades and one research interest has been focused on preparing UHPC with low-priced raw materials or industrial by-products. In this study, a green UHPC which used high volumes of fly ash and river sand as part of raw materials was prepared, and the objective is to investigate the nano-mechanical behavior of the UHPC using nanoindentation. The results show that the hydration products, which account for about half of the paste by volume, are mainly high-stiffness hydrate phases, and significant quantities of unreacted cement and fly ash have higher mechanical properties than the hydration products and can function as micro-aggregates to strengthen the UHPC paste. Moreover, the mechanical properties of the paste near aggregate or fiber surfaces are similar to those of the bulk paste, which indicates that the UHPC has a strong and efficient bond at the interfacial zone. The experimental findings at the nano-scale could help to understand the macro-performance of the green UHPC. © 2014 Elsevier Ltd. All rights reserved.

Luo Y.-H.,Nanjing Southeast University | Wu G.-G.,Nanjing Southeast University | Sun B.-W.,Nanjing Southeast University
Journal of Chemical and Engineering Data | Year: 2013

A process mathematic model of seed batch desupersaturation experiments and induction time experiments for the investigation of growth and nucleation kinetics of biapenem through an antisolvent procedure in water/ethanol (antisolvent) system was developed in this work. The kinetic parameters for growth and nucleation were estimated by using in situ technology: attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy for solute concentration, focused beam reflectance measurement (FBRM) for CLD moments, and particle vision and measurement (PVM) for particle image measurement. The challenging aspect for the development of this model was the recovery of crystal size distributions (CSDs) from the chord length distribution (CLD) moments; batch experiments were designed for the estimation of this relationship. The mathematic model in this work was confirmed by a comparison between model predictions and experimental data. © 2013 American Chemical Society.

Zhou D.,Nanjing Southeast University | Zhong D.,Nanjing Southeast University | He Y.,Aston University
Bioinformatics | Year: 2014

Motivation: In molecular biology, molecular events describe observable alterations of biomolecules, such as binding of proteins or RNA production. These events might be responsible for drug reactions or development of certain diseases. As such, biomedical event extraction, the process of automatically detecting description of molecular interactions in research articles, attracted substantial research interest recently. Event trigger identification, detecting the words describing the event types, is a crucial and prerequisite step in the pipeline process of biomedical event extraction. Taking the event types as classes, event trigger identification can be viewed as a classification task. For each word in a sentence, a trained classifier predicts whether the word corresponds to an event type and which event type based on the context features. Therefore, a well-designed feature set with a good level of discrimination and generalization is crucial for the performance of event trigger identification. Results: In this article, we propose a novel framework for event trigger identification. In particular, we learn biomedical domain knowledge from a large text corpus built from Medline and embed it into word features using neural language modeling. The embedded features are then combined with the syntactic and semantic context features using the multiple kernel learning method. The combined feature set is used for training the event trigger classifier. Experimental results on the golden standard corpus show that >2.5% improvement on F-score is achieved by the proposed framework when compared with the state-of-the-art approach, demonstrating the effectiveness of the proposed framework. © 2014 The Author 2014.

Xie Y.,Nanjing Southeast University | Xie Y.,Suzhou University | Fang X.,Nanjing Southeast University | Fang X.,Suzhou University
Electrochimica Acta | Year: 2014

The manganese dioxide-titanium nitride (MnO2-TiN) nanotube hybrid has been designed to improve its electroactivity and conductivity for a supercapacitor application. Titanium nitride (TiN) nanotube array was prepared by an anodization process of titanium in ethylene glycol (EG) solution containing ammonium fluoride, subsequent calcination process in an air atmosphere, and final nitridation process in an ammonia atmosphere. Electroactive MnO2 was then loaded into well-aligned TiN nanotubes to form MnO2-TiN nanotube hybrid with well-designed shell layer of MnO2 through a controlled cyclic voltammetry electrodeposition process, which was directly supported on ultra thin and supple titanium foil to establish a bendable electrode. The morphology and microstructure of MnO 2-TiN nanotube hybrid were characterized by scanning electron microscopy and X-ray diffraction. The electrochemical capacitance was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. The villiform MnO2 thin shell layer was fully covered on TiN nanotube walls to form a coaxial heterogeneous structure. Superior electrical conductivity and accessible nanochannels of TiN contributed to a high capacitance performance of MnO2. The specific capacitance of MnO2-TiN was determined to be 853.3 F g-1 (or 213.2 mF cm-2) at a current density of 1.0 A g-1 (or 0.25 mA cm-2). All-solid-state flexible supercapacitor was constructed using two symmetric film electrodes of MnO2-TiN nanotube hybrid and a polyvinyl alcohol gel electrolyte of KOH-KI-EG. The volume specific capacitance, energy and power density were determined to be 4.01 F cm-3, 1.81 mW h cm-3 and 32.8 mW cm-3 at a high potential window of 1.8 V and a current density of 2.0 mA cm-2. Such MnO2-TiN nanotube hybrid electrode material exhibited effective energy storage in flexible supercapacitor application. © 2013 Elsevier Ltd.

He Y.,Sichuan University | Guo H.,Nanjing Southeast University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We propose a topological defect or instanton solution with nonzero Hopf invariant to the 3+1D non-Abelian gauge theory coupled with scalar fields. This solution, which we call Hopf defect, represents a spacetime event that makes a 2. π rotation of vacuum manifold of the monopole. Although the action of this Hopf defect is logarithmically divergent, it may still give relevant contributions in a finite-sized system. Since the Chern-Simons term for the unbroken U(1) gauge field may appear in the low energy effective theory, the Hopf defect may possibly generate a phase factor change for the monopoles. © 2014 The Authors.

Fu Y.,Nanjing Southeast University
PrimeAsia 2010 - 2nd Asia Pacific Conference on Postgraduate Research in Microelectronics and Electronics | Year: 2010

Considering the issues involved in the multiple relaying cooperation such as the perfect synchronization and high complexity, some single-relay selection schemes are presented in this paper for two-way relaying networks, where this network is consisted of two source nodes and multiple relay nodes, each node with single antenna. The novel single-relay selection schemes based on the transmission rate maximization, equivalent channel gain maximization, and the minimization of the harmonic mean of channel gains, respectively, are proposed to determine the best relay. Numerical simulations are performed to show the performance of the proposed schemes in terms of the capacity and the cumulative distribution function of the two-way relaying network.

She X.,Nanjing Southeast University | Yin Y.,Nanjing Southeast University | Zhang X.,Nanjing Southeast University
Energy Conversion and Management | Year: 2014

A new energy-efficient refrigeration system subcooled by liquid desiccant dehumidification and evaporation was proposed in this paper. In the system, liquid desiccant system could produce very dry air for an indirect evaporative cooler, which would subcool the vapor compression refrigeration system to get higher COP than conventional refrigeration system. The desiccant cooling system can use the condensation heat for the desiccant regeneration. Thermodynamic analysis is made to discuss the effects of operation parameters (condensing temperature, liquid desiccant concentration, ambient air temperature and relative humidity) on the system performance. Results show that the proposed hybrid vapor compression refrigeration system achieves significantly higher COP than conventional vapor compression refrigeration system, and even higher than the reverse Carnot cycle at the same operation conditions. The maximum COPs of the hybrid systems using hot air and ambient air are 18.8% and 16.3% higher than that of the conventional vapor compression refrigeration system under varied conditions, respectively. © 2013 Elsevier Ltd. All rights reserved.

Da F.,Nanjing Southeast University | Dong F.,Nanjing Southeast University
Optics Letters | Year: 2012

A novel method for windowed Fourier transform (WFT) profilometry is presented. This method is based on improved S-transform. The impact of the second order derivative of the phase (ψ"(b)) to the ridge of S-transform is derived, and how to estimate this deviation is discussed. An important conclusion that more accurate instantaneous frequency can be obtained after removing this deviation is shown. Thus, an accurate phase map of the fringe pattern is obtained by using the WFT based on the window size map, and this map is related to the instantaneous frequency. The method is compared with the WFT based on the wavelet transform. A numerical simulation and experimental example have shown its validity in practical applications. © 2012 Optical Society of America.

Xiao J.,Nanjing Southeast University | Sun X.,Nanjing Southeast University
Optics Express | Year: 2012

A vector mode solver for bending waveguides by using a modified finite-difference (FD) method is developed in a local cylindrical coordinate system, where the perfectly matched layer absorbing boundary conditions are incorporated. Utilizing Taylor series expansion technique and continuity condition of the longitudinal field components, a standard matrix eigenvalue equation without the averaged index approximation approach for dealing with the discrete points neighboring the dielectric interfaces is obtained. Complex effective indexes and field distributions of leaky modes for a typical rib bending waveguide and a silicon wire bend are presented, and solutions accord well with those from the film mode matching method, which shows the validity and utility of the established method. © 2012 Optical Society of America.

Tian Y.-P.,Nanjing Southeast University | Wang Q.,Nanjing Southeast University
Automatica | Year: 2013

This paper considers the problem of distributed control of rigid formation shapes in the plane for multi-agent systems. A constructive perturbation method is proposed and combined with the conventional gradient control law. The proposed control law stabilizes the desired rigid formation in a global sense for all initial conditions except the case when a pair of communicating agents happen to have the same initial location. It also avoids collisions between any two communicating agents during the motion. Simulation results are provided to illustrate the effectiveness of the control algorithm. © 2013 Elsevier Ltd. All rights reserved.

Li X.,Fudan University | Xiao S.,Fudan University | Cai B.,Nanjing Southeast University | He Q.,Fudan University | And 2 more authors.
Optics Letters | Year: 2012

We show that a flat metasurface with a parabolic reflection-phase distribution can focus an impinging plane wave to a point image in reflection geometry. Our system is much thinner than conventional geometric-optics devices and does not suffer the energy-loss issues encountered by many metamaterial devices working in transmission geometry. We designed realistic microwave samples and performed near-field scanning experiments to verify the focusing effect. Experimental results are in good agreement with full wave simulations, model calculations, and theoretical analyses. © 2012 Optical Society of America.

Zheng D.,Nanjing Southeast University | Da F.,Nanjing Southeast University
Optics Express | Year: 2012

A recently proposed phase coding method for absolute phase retrieval performs well because its codeword is embedded into phase domain rather than intensity. Then, the codeword can determine the fringe order for the phase unwrapping. However, for absolute phase retrieval with a large number of codewords, the traditional phase coding method becomes not so reliable. In this paper, we present a novel phase coding method to tackle this problem. Six additional fringe images can generate more than 64(26) unique codewords for correct absolute phase retrieval. The novel phase coding method can be used for absolute phase retrieval with high frequency. Experiment results demonstrate the proposed method is effective. © 2012 Optical Society of America.

Gu B.,Nanjing Southeast University | Cui Y.,Nanjing Southeast University
Optics Express | Year: 2012

Based on the vectorial Rayleigh-Sommerfeld formulas under the weak nonparaxial approximation, we investigate the propagation behavior of a lowest-order Laguerre-Gaussian beam with azimuthal-variant states of polarization. We present the analytical expressions for the radial, azimuthal, and longitudinal components of the electric field with an arbitrary integer topological charge m focused by a nonaperturing thin lens. We illustrate the three-dimensional optical intensities, energy flux distributions, beam waists, and focal shifts of the focused azimuthal-variant vector beams under the nonparaxial and paraxial approximations. © 2012 Optical Society of America.

Wang C.,Nanjing Southeast University | Da F.,Nanjing Southeast University
Optics Express | Year: 2012

The phase demodulation method of adaptive windowed Fourier transform (AWFT) is proposed based on Hilbert-Huang transform (HHT). HHT is analyzed and performed on fringe pattern to obtain instantaneous frequencies firstly. These instantaneous frequencies are further analyzed based on the condition of AWFT to locate local stationary areas where the fundamental spectrum will not be interfered by high-order spectrum. Within each local stationary area, the fundamental spectrum can be extracted accurately and adaptively by using AWFT with the background, which has been determined previously with the presented criterion during HHT, being eliminated to remove the zero-spectrum. This method is adaptive and unconstrained by any precondition for the measured phase. Experiments demonstrate its robustness and effectiveness for measuring the object with discontinuities or complex surface. © 2012 Optical Society of America.

Li R.,Nanjing Southeast University | Wei H.,Chongqing University
International Journal of Machine Learning and Cybernetics | Year: 2016

This paper is concerned with the sampled-data synchronization issues for delayed memristive neural networks with Markovian jumping and reaction–diffusion terms. In the frame work of inequality techniques and a useful Lyapunov functional, some new testable algebraic criteria are obtained to ensure the stability of the error system, and thus, the master system can synchronize with the slave system. Finally, an illustrative example is exploited to demonstrate the performance and effectiveness of the developed approach. © 2015, Springer-Verlag Berlin Heidelberg.

Xia M.,Nanjing Southeast University | Xu Z.,Nanjing Southeast University
Computers and Industrial Engineering | Year: 2011

To improve the consistency of a preference relation is a hot topic in decision making. Wang and Chen (2008) gave a simple method to construct the complete fuzzy complementary preference relation from only n - 1 pairwise comparisons. However, some values may not be in the defined scope and need to be transformed, and thus some original information may be lost in the transformation process. In this paper, we propose a new method to avoid this issue based on the multiplicative consistency of the fuzzy complementary preference relation and apply it to fuzzy Analytic Hierarchy Process (AHP). An example is further given to illustrate our method. © 2011 Elsevier Ltd. All rights reserved.

You X.,Nanjing Southeast University | Wang D.,Nanjing Southeast University | Zhu P.,Nanjing Southeast University | Sheng B.,Nanjing Southeast University
IEEE Journal on Selected Areas in Communications | Year: 2011

Cell edge effect has been recently paid much attention in the development of new generation mobile communications systems because it can cause serious performance degradation in cell edge. In this paper, the cell edge effects of traditional cellular systems and distributed cellular systems are evaluated and compared in environments with or without intercell interference (ICI). Three performance metrics are proposed to quantify the cell edge effect of cellular systems. A lower bound is derived on the location-specific spectral efficiency of the collocated antenna system (CAS). Both an approximate expression and an iterative method to quantify the location-specific spectral efficiency of the distributed antenna system (DAS) are presented. Moreover, based on these results, the proposed performance metrics are analyzed and discussed. Finally, numerical results for typical configurations of the cellular systems are presented to validate the theoretical results, and it is also shown that the cell edge performance of the DAS is better than that of the CAS. © 2011 IEEE.

Gang R.,Nanjing Southeast University | Zhuping Z.,Nanjing Southeast University
Expert Systems with Applications | Year: 2011

It is important to establish the decision of traffic safety planning by forecasting the development tendency of traffic accident according to the related data of traffic safety in former years. In order to solve the drawbacks of BP neural network, a novel approach which combines particle swarm optimization and support vector machine (PSO-SVM) is presented to traffic safety forecasting. Firstly, influencing factors of traffic safety and evaluation indexes are analyzed, then traffic safety forecasting model by PSO-SVM is established according to the influencing factors. Finally, the data about traffic safety in China from 1970 to 2006 are applied to research the forecasting ability of the proposed method. The experimental results show that traffic safety forecasting by PSO-SVM is better than that by BP neural network. © 2011 Published by Elsevier Ltd.

Xie X.-J.,Qufu Normal University | Duan N.,Xuzhou Normal University | Yu X.,Nanjing Southeast University
IEEE Transactions on Automatic Control | Year: 2011

This technical note considers a class of high-order stochastic nonlinear systems with stochastic integral input-to-state stability (SiISS) inverse dynamics, and drift and diffusion terms depending upon the stochastic inverse dynamics and all the states. A new design and analysis approach to the problem of state-feedback global regulation is developed to guarantee that all the signals of the closed-loop system are bounded almost surely and the states can be regulated to zero almost surely. © 2010 IEEE.

Du H.,Nanjing Southeast University | Li S.,Nanjing Southeast University | Qian C.,University of Texas at San Antonio
IEEE Transactions on Automatic Control | Year: 2011

This note investigates the finite-time attitude control problems for a single spacecraft and multiple spacecraft. First of all, a finite-time controller is designed to solve finite-time attitude tracking problem for a single spacecraft. Rigorous proof shows that the desired attitude can be tracked in finite time in the absence of disturbances. In the presence of disturbances, the tracking errors can reach a region around the origin in finite time. Then, based on the neighbor rule, a distributed finite-time attitude control law is proposed for a group of spacecraft with a leader-follower architecture. Under the finite-time control law, the attitude synchronization can be achieved in finite time. © 2011 IEEE.

Qu Y.,Nanjing University | Cheng G.,Nanjing Southeast University
IEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans | Year: 2011

Web ontologies provide shared concepts for describing domain entities and thus enable semantic interoperability between applications. To facilitate concept sharing and ontology reusing, we developed Falcons Concept Search, a novel keyword-based ontology search engine. In this paper, we illustrate how the proposed mode of interaction helps users quickly find ontologies that satisfy their needs and present several supportive techniques including a new method of constructing virtual documents of concepts for keyword search, a popularity-based scheme to rank concepts and ontologies, and a way to generate query-relevant structured snippets. We also report the results of a usability evaluation as well as user feedback. © 2011 IEEE.

Wu Q.,Nanjing Southeast University
Expert Systems with Applications | Year: 2011

This paper presents a new version of fuzzy support vector machine to diagnose automatic car assembly fault diagnosis, the input and output variables are described as fuzzy numbers and the metric on fuzzy number space is defined. Then by combining the fuzzy theory with v-support vector machine, the fuzzy v-support vector classifier machine (Fv-SVCM) is proposed. A fault diagnosis method based on Fv-SVCM and its relevant parameter-choosing algorithm is put forward. The results of the application in car assembly diagnosis confirm the feasibility and the validity of the diagnosis method. Compared with the fuzzy neural network (FNN) model, Fv-SVCM method requires fewer samples and has better estimating precision. © 2010 Elsevier Ltd. All rights reserved.

Wu Y.-Q.,Qufu Normal University | Yu J.-B.,Nanjing Southeast University | Zhao Y.,Nanjing Southeast University
IEEE Transactions on Automatic Control | Year: 2011

This note studies the global asymptotic regulation problem for a class of nonlinear systems with integral input-to-state stable (iISS) inverse dynamics by output feedback. It does not require a priori knowledge of the sign of the high-frequency gain. The considered system represents more general classes of nonlinear uncertain systems. The novelty of this note lies in the observer whose gain comes from a time-varying Riccati differential equation. © 2006 IEEE.

Wang J.,Nanjing Southeast University | Li X.,Nanjing Southeast University
Journal of Applied Polymer Science | Year: 2010

In the current work, interpenetrating polymer network (IPN) silicone hydrogels are prepared by UVinitiated polymerization of acrylate monomers including siloxane macromer, methacryloxypropyl tris (trimethylsiloxy) silane (TRIS) and N,N-dimethylacrylamide (DMA)/ N-vinyl-2-pyrrolidone (NVP) in the presence of free radical and cationic photoinitiators. The polymerization mechanism is investigated preliminarily by the formation of gel network. The morphology of the hydrogels is characterized by fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and transmission electron microscope (TEM). The results show that the IPN hydrogels exhibit a heterogeneous morphology. The surface wettability is examined by the contact angle goniometer. The result reveals that the IPN silicone hydrogels possess hydrophilic surfaces with the lowest water contact angle of 59°. Furthermore, the oxygen permeability of the hydrogels is measured by an oxygen transmission tester. The results indicate that the IPN silicone hydrogels have excellent oxygen permeability with the highest Dk of 226 barrer. © 2010 Wiley Periodicals, Inc.

Li Y.,Nanjing Southeast University | Li T.,Nanjing Southeast University | Yao M.,Nanjing Southeast University | Liu S.,Nanjing Southeast University
Journal of Materials Chemistry | Year: 2012

This study described a facile and effective route for the synthesis of structurally uniform and electrochemically active nitrogen-doped hollow carbon spheres (NHCSs) via pyrolysis of hollow poly(o-phenylenediamine) (PoPD) spheres. The characters and the mechanism of the transformation between the as-prepared PoPD and the NHCSs were studied. Results showed that the ladder aromatic structure of the as-prepared PoPD was transformed into a polycyclic-type structure in which nitrogen atoms were successfully incorporated into the graphitic structures to replace the carbon atoms. The as-prepared NHCSs showed a much higher electrocatalytic current than multi-wall carbon nanotubes and nitrogen-doped carbon nanotubes for the oxygen reduction reaction through a four-electron pathway in alkaline solution. The enhanced catalytic activity of NHCSs for ORR arose from the doping of nitrogen in the form of quaternary nitrogen, along with pyridinic N and pyrrolic N. The NHCSs also presented high methanol tolerance and long-term operational stability. The results showed that the NHCSs had a promising application in direct methanol fuel cells and provided a new method to synthesize carbon-based metal-free electrocatalysts from organic polymers. © The Royal Society of Chemistry 2012.

Wang Y.,Nanjing Southeast University | Liao H.,Nanjing Southeast University | Wu Y.,Nanjing Southeast University | Yang J.,Nanjing Southeast University
Materials and Design | Year: 2014

Microstructure and mechanical properties of as-cast and as-extruded Al-Si-Mg alloys with different Si content are investigated by tensile test, microstructure observation. High density of Si particles in the Al alloys can induce dynamic recrystallization during hot extrusion and it becomes more matured with an increase in the density of Si particles. The tensile strength of as-cast and as-extruded alloys can be improved with the increase of Si content and hot extrusion make the elongation of alloys increase dramatically. Considerable grain refining effect caused by recrystallization occurred during hot extrusion of S2 (equivalently commercial A356 alloy) and S3 (near eutectic alloy) alloys plays an important role in the improvement of elongation. A good combination of strength and elongation for the as-extruded S3 alloy indicates that near eutectic Al-Si alloys can be hot-extruded to produce aluminum profiles with high performance. © 2013 Elsevier Ltd.

Wang S.K.,Nanjing Southeast University | Wang J.,Nanjing Southeast University | Chan K.S.,City University of Hong Kong
New Journal of Physics | Year: 2014

Silicene is a 2D topological insulator due to its fairly large spin-orbital interaction and features a buckled lattice structure that allows one to control the effective mass of Dirac electrons by a perpendicular electric field. We propose the use of a spatially alternative electric field to generate multiple topologically-protected interface states (TIS) in the bulk silicene. It is shown that when the valley-dependent electron mass (defining the Chern number of an insulating bulk silicene) changes its sign or discontinues due to spatial variation of the electric field, multiple TIS appear in the insulating bulk silicene. The TIS come from the K and valleys and sustain dissipationless valley or spin-valley-dependent currents, which are immune to both the valley-conservation and spin-observation scattering. It is also found that the coupling among TIS due to spatial electron tunneling excites the TIS, and whether there is an excitation gap or not depends on the even or odd TIS number. Our findings may shed light on manufacturing topological electron devices. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Shi J.J.,Nanjing Southeast University | Sun W.,Nanjing Southeast University
Cement and Concrete Composites | Year: 2014

The influence of phosphate as a corrosion inhibitor on the corrosion behavior of as-received and pre-rusted reinforcing steels in mortar specimens was investigated after 360 days exposure in 3.5% NaCl solution. This involved the use of electrochemical techniques for studying the steel surface reactions and microscopic observations of the steel-mortar interface. The electrochemical methods, including electrochemical impedance spectroscopy (EIS) and measurements of corrosion potential (Ecorr) and linear polarization resistance (LPR), were employed to evaluate the corrosion tendency and general corrosion rate of steel. In addition, the pitting corrosion resistance of steel was also determined by cyclic polarization (CP) measurements. The results indicate that different from nitrite, which is generally accepted as an anodic inhibitor, phosphate may be a cathodic inhibitor according to its reduced corrosion rate and more negative Ecorr at the same dosage as nitrite in mortar specimens. The study also reveals that the inhibiting efficiency of phosphate against general corrosion of both as-received and pre-rusted specimens is lower than 10%, which is inferior to nitrite in some respects. However, as indicated by cyclic polarization measurements, the presence of phosphate provides slightly higher pitting corrosion resistance in comparison to nitrite. Furthermore, it suggests that the corrosion inhibition mechanism of phosphate in mortars mainly depends on a dual effect occurring at the steel-mortar interface. Furthermore, it is confirmed that phosphate has little effect on the long-term mechanical properties of mortars. © 2013 Elsevier Ltd. All rights reserved.

Wang B.,Nanjing Southeast University | Hobbs B.F.,Johns Hopkins University
Electric Power Systems Research | Year: 2014

U.S. Independent System Operators (ISOs) are creating short-run markets for so-called "flexiramp". The aim of these markets is to ensure that enough flexible generation capacity is on-line to manage the increasingly volatile net loads resulting from growth in renewable energy. In particular, we assume that the purpose of flexiramp is to improve the expected performance, in terms of costs, prices, and reliability, of the ISOs' deterministic market models. Therefore, we compare the solutions of (1) a deterministic dispatch model with a flexiramp constraint that simulates ISO operations with (2) a stochastic dispatch model that, by definition, obtains schedules that minimize expected cost. Dispatch, prices, settlements, and market efficiency are contrasted in a simplified case study to explore the fundamental reasons for successes (and failures) of flexiramp markets. The results illustrate how flexiramp can enhance market efficiency. However, they also show that procuring flexiramp is insufficient to minimize expected costs, and that market parameters affect the quality of the solutions. The simulations furthermore show that deterministic markets with flexiramp can yield either higher or lower prices than the stochastic optimum. We propose a penalty-based approach to mitigate possible biases towards choosing capacity with high energy costs to provide flexiramp, and conclude that market operators will need to monitor market performance and adjust flexiramp parameters in order to maximize market efficiency. © 2014 Elsevier B.V.

Zhao X.,Nanjing Southeast University | Sun Z.-Z.,Nanjing Southeast University
Journal of Computational Physics | Year: 2011

Combining order reduction approach and L1 discretization, a box-type scheme is presented for solving a class of fractional sub-diffusion equation with Neumann boundary conditions. A new inner product and corresponding norm with a Sobolev embedding inequality are introduced. A novel technique is applied in the proof of both stability and convergence. The global convergence order in maximum norm is O(τ2-α+h2). The accuracy and efficiency of the scheme are checked by two numerical tests. © 2011 Elsevier Inc.

Zhang M.-L.,Nanjing Southeast University | Zhou Z.-H.,Nanjing University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

Co-training is one of the major semi-supervised learning paradigms that iteratively trains two classifiers on two different views, and uses the predictions of either classifier on the unlabeled examples to augment the training set of the other. During the co-training process, especially in initial rounds when the classifiers have only mediocre accuracy, it is quite possible that one classifier will receive labels on unlabeled examples erroneously predicted by the other classifier. Therefore, the performance of co-training style algorithms is usually unstable. In this paper, the problem of how to reliably communicate labeling information between different views is addressed by a novel co-training algorithm named CoTrade. In each labeling round, CoTrade carries out the label communication process in two steps. First, confidence of either classifier's predictions on unlabeled examples is explicitly estimated based on specific data editing techniques. Secondly, a number of predicted labels with higher confidence of either classifier are passed to the other one, where certain constraints are imposed to avoid introducing undesirable classification noise. Experiments on several real-world datasets across three domains show that CoTrade can effectively exploit unlabeled data to achieve better generalization performance. © 2006 IEEE.

Liu X.,Nanjing Southeast University | Liu X.,University of Southern California | Mendel J.M.,University of Southern California
IEEE Transactions on Fuzzy Systems | Year: 2011

Based on a new continuous Karnik-Mendel (KM) algorithm expression, this paper proves that the centroid computation of an interval type-2 fuzzy set using KM algorithms is equivalent to the Newton-Raphson method in root-finding, which reveals the mechanisms in KM algorithm computation. The theoretical results of KM algorithms are re-obtained. Different from current KM algorithms, centroid computation methods that use different root-finding routines are provided. Such centroid computation methods can obtain the exact solution and are different from the current approximate methods using sampled data. Further improvements and analysis of the centroid problem using root-finding and integral computation techniques are also possible. © 2006 IEEE.

Tao Y.,Nanjing Southeast University | Liang X.,Nanjing Southeast University | Wang J.,Nanjing Southeast University | Zhao C.,Nanjing Southeast University
Optics Express | Year: 2015

Visible light communication (VLC) has drawn much attention in the field of high-rate indoor wireless communication. While most existing works focused on point-to-point VLC technologies, few studies have concerned multiuser VLC, where multiple optical access points (APs) transmit data to multiple user receivers. In such scenarios, inter-user interference constitutes the major factor limiting the system performance. Therefore, a proper scheduling scheme has to be proposed to coordinate the interference and optimize the whole system performance. In this work, we aim to maximize the sum rate of the system while taking into account user fairness by appropriately assigning LED lamps to multiple users. The formulated scheduling problem turns out to be a maximum weighted independent set problem. We then propose a novel and efficient resource allocation method based on graph theory to achieve high sum rates. Moreover, we also introduce proportional fairness into our scheduling scheme to ensure the user fairness. Our proposed scheduling scheme can, with low complexity, achieve more multiplexing gains, higher sum rate, and better fairness than the existing works. © 2014 Optical Society of America.

Luo X.,Nanjing Southeast University | Qiu T.,Nanjing Southeast University | Lu W.,Nanjing Southeast University | Ni Z.,Nanjing Southeast University
Materials Science and Engineering R: Reports | Year: 2013

Owing to its excellent electrical, mechanical, thermal and optical properties, graphene has attracted great interests since it was successfully exfoliated in 2004. Its two dimensional nature and superior properties meet the need of surface plasmons and greatly enrich the field of plasmonics. Recent progress and applications of graphene plasmonics will be reviewed, including the theoretical mechanisms, experimental observations, and meaningful applications. With relatively low loss, high confinement, flexible feature, and good tunability, graphene can be a promising plasmonic material alternative to the noble metals. Optics transformation, plasmonic metamaterials, light harvesting etc. are realized in graphene based devices, which are useful for applications in electronics, optics, energy storage, THz technology and so on. Moreover, the fine biocompatibility of graphene makes it a very well candidate for applications in biotechnology and medical science. © 2013 Elsevier B.V.

Yang W.-X.,Nanjing Southeast University
Optics Letters | Year: 2015

We investigate the high-order harmonic generation (HHG) in a semiconductor quantum dot (SQD) and metallic nanorod (MNR) complex driven by a moderate intensity (<1012 W/cm2) frequency-chirped Gaussian few-cycle pulse. Our numerical results indicate that the cutoff energy of the HHG can be controlled by optimizing the shape of the MNR and surface-to-surface distance between the SQD and the MNR. We also show that the extreme ultraviolet supercontinuum harmonics (25 eV maximal photon energy) and isolated ultrashort pulses (2.67-4.36 fs FWHM) are achievable. © 2015 Optical Society of America.

Ma S.,Nanjing Southeast University | Xue J.,Nanjing Southeast University | Zhou Y.,Nanjing Southeast University | Zhang Z.,Nanjing Southeast University
Journal of Materials Chemistry A | Year: 2014

ZnO/Ag2O heterostructures were successfully synthesized via a simple one-step photochemical route. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). Photocatalytic activity toward degradation of a methylene blue (MB) aqueous solution under ultraviolet (UV) and visible light was investigated. The results showed that the as-prepared ZnO/Ag2O heterostructures significantly enhanced the UV and visible photocatalytic activity compared with pure ZnO and Ag2O. In particular, the rates of degradation using the as-prepared ZnO/Ag2O heterostructures were 27.4 and 15.6 times faster than that using bare ZnO nanoparticles under UV and visible light irradiation, respectively. Furthermore, the as-prepared ZnO/Ag2O heterostructures could be easily recycled in UV and visible photocatalytic applications due to the low concentration of surface defects. Moreover, the ZnO/Ag2O heterostructures could also degrade MB dye with high efficiency in various water types such as Changjiang river water, tap water, and deionized water, which will greatly promote their application in the area of environmental remediation. © the Partner Organisations 2014.

Nie X.,Nanjing Southeast University | Huang Z.,Jimei University
Neurocomputing | Year: 2012

In this paper, high-order synaptic connectivity is introduced into competitive neural networks and the multistability and multiperiodicity issues are discussed for high-order competitive neural networks with a general class of activation functions. Based on decomposition of state space, Halanay inequality, Cauchy convergence principle and inequality technique, some sufficient conditions are derived for ascertaining equilibrium points to be located in any designated region and to be locally exponentially stable. As an extension of multistability, some similar results are presented for ensuring multiple periodic solutions when external inputs and time delay are periodic. The obtained results are different from and less restrictive than those given by Nie and Cao (2009 [25]), and the assumption (H1A) by Nie and Cao (2009 [25]) is relaxed. It is shown that high-order synaptic connectivity plays an important role on the number of equilibrium points and their dynamics. As a consequence, our results refute traditional viewpoint: high-order synaptic connectivity has faster convergence rate and greater storage capacity than first-order one. Finally, three examples with their simulations are given to show the effectiveness of the obtained results. © 2011 Elsevier B.V.

Zhang Z.,Nanjing Southeast University | Qian S.,Nanyang Technological University | Ma H.,Nanjing Southeast University
Construction and Building Materials | Year: 2014

In this paper, the mechanical properties and self-healing behavior of Engineered Cementitious Composite (ECC) are investigated. Three ECC mix proportions with different volume of fly ash are used in this research. The mechanical properties of ECC are revealed via compressive strength, deflection capacity and cracking behavior. Meanwhile, the self-healing behavior of ECCs is investigated by sorptivity test and rapid chloride penetration test (RCPT). Specimens are pre-loaded first to produce micro-cracks, followed by sorptivity and RCPT tests. It is found that both compressive strength and crack width decrease with increasing volume of fly ash, while deflection capacity shows the opposite trend. Micro-cracks produced by pre-loading heal themselves after cured in water, thus decrease sorptivity and charge passed of micro-cracked specimen. Subsequent Environment Scanning Electron Microscope (ESEM) observations also confirm the above findings. The sorptivity test result suggests that ECC mixture with fly ash/cement ratios of 4.0 by weight reveals best self-healing behavior. Therefore, with excellent capacity of crack width control, deformability and self-healing behavior, ECC can be an ideal material for durable concrete infrastructure. © 2013 Elsevier Ltd. All rights reserved.

Wang H.,Nanjing Southeast University
Neural Networks | Year: 2012

Subspace learning is a core issue in pattern recognition and machine learning. Linear graph embedding (LGE) is a general framework for subspace learning. In this paper, we propose a structured sparse extension to LGE (SSLGE) by introducing a structured sparsity-inducing norm into LGE. Specifically, SSLGE casts the projection bases learning into a regression-type optimization problem, and then the structured sparsity regularization is applied to the regression coefficients. The regularization selects a subset of features and meanwhile encodes high-order information reflecting a priori structure information of the data. The SSLGE technique provides a unified framework for discovering structured sparse subspace. Computationally, by using a variational equality and the Procrustes transformation, SSLGE is efficiently solved with closed-form updates. Experimental results on face image show the effectiveness of the proposed method. © 2011 Elsevier Ltd.

Yao X.,Nanjing Southeast University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2013

The relaxation of geometrical frustration under different factors is investigated by comparing the density of states and magnetic behavior obtained in Wang-Landau simulation. Starting from the same triangular antiferromagnetic system with high frustration, three typical ways, in which the non-trivial high degeneracy of ground states is lifted by different relaxative factors, are revealed. Correspondingly, the typical magnetic behavior with M0/3 (where M0 is the saturated magnetization) plateau in frustrated triangular system, shows distinct variations in these three cases. © 2012 Elsevier B.V. All rights reserved.

Ye W.,Nanjing Southeast University | Wang N.,Nanjing Southeast University
Physical Review C - Nuclear Physics | Year: 2013

We study the influence of the ratio of level-density parameters at saddle to that at ground-state configuration (af/an) on the sensitivity of fission cross sections (σfiss) to presaddle dissipation effects by comparing fission excitation functions measured in the 3He + 197Au (208Pb) reactions with three distinct types of model calculations: the standard Bohr-Wheeler theory with af/an = 1 (i) and af/an ≠ 1 (ii) as well as the Langevin approach with af/an ≠ 1 (iii). It is shown that both cases (i) and (ii) cannot provide a reasonable, satisfactory description of the measured σfiss. A presaddle friction strength (β) of (4-4.5) × 1021 s-1 is extracted through reproducing data with Langevin simulations. We find from the comparison of the experimental and calculated σfiss in cases (ii) and (iii) that a precise determination of β depends sensitively on af/an. The finding indicates that level-density parameters play a significant role in accurately probing presaddle friction; that is, to stringently constrain β it is important to take into account a realistic and an elaborate evaluation of a f/an in theoretical calculations. We further find that high energy increases the sensitivity of σfiss to β, suggesting that in experiments, to obtain precise information of presaddle dissipation by measuring σfiss, it is best to populate a compound nucleus with high energy. © 2013 American Physical Society.

Lu Z.,Nanjing Southeast University
Frontiers of Physics | Year: 2016

This article presents a review of our present understanding of the spin structure of the unpolarized hadron. Particular attention is paid to the quark sector at leading twist, namely, the quark Boer–Mulders function, which describes the transverse polarization of the quark inside an unpolarized hadron. After introducing the operator definition of the Boer–Mulders function, a detailed treatment of different non-perturbative calculations of the Boer–Mulders functions is provided. The phenomenology in Drell–Yan processes and semi-inclusive leptoproduction, including the extraction of the quark and antiquark Boer–Mulders functions from experimental data, is presented comprehensively. Finally, prospects for future theoretical studies and experimental measurements are presented in brief. © 2016, The Author(s).

Wang Y.-H.A.,University of Alabama | Zhang X.,University of Alabama | Zhang X.,Nanjing Southeast University | Bao N.,University of Alabama | And 3 more authors.
Journal of the American Chemical Society | Year: 2011

Monodisperse wurtzite CuInxGa1 - xS2 nanocrystals have been synthesized over the entire composition range using a facile solution-based method. Depending on the chemical composition and synthesis conditions, the morphology of the nanocrystals can be controlled in the form of bullet-like, rod-like, and tadpole-like shapes. The band gap of the nanocrystals increases linearly with increasing Ga concentration, with band gap values for the end members being close to those observed in the bulk. Colloidal suspensions of the nanocrystals are attractive for use as inks for low-cost fabrication of thin film solar cells by spin or spray coating. © 2011 American Chemical Society.

Tian Y.-P.,Nanjing Southeast University
ASCC 2011 - 8th Asian Control Conference - Final Program and Proceedings | Year: 2011

This paper studies the high-order consensus problem for heterogeneous multi-agent systems with unknown communication delays. It is shown that high-order consensus may exist in systems with heterogeneous agents. A necessary and sufficient condition is given for the existence of high-order consensus solution to heterogeneous multi-agent systems. The obtained condition shows that for systems with diverse communication delays, high-order consensus does not require each self-delay of agent is equal to the corresponding communication delay. A matching condition for self-delays and communication delays is derived. Finally, when communication delays are unknown, an adaptive adjustment mechanism is proposed for on-line adjusting self-delays. © 2011 Asian Control Association.

Xie J.,Nanjing Southeast University | Yan C.,Nanjing Southeast University | Zhang Y.,Nanjing Southeast University | Gu N.,Nanjing Southeast University
Chemistry of Materials | Year: 2013

Monodisperse magnetic Mn-Zn ferrite nanostructures with various morphologies have been successfully synthesized via high-temperature decomposition of metal acetylacetonate (acac) in the presence of oleic acid (OA) and oleyamine (OAm). In a classical crystal nucleation/growth process, differential stabilization of OA on specific crystal facets may alter relative crystal growth rates, resulting in the formation of zero-dimensional (0-D) spherical, cubical, and starlike nanocrystals (ca. 9, 11, 16 nm), respectively. Furthermore, shortening nucleation duration might bring a deficient nucleation and a rapid increase in monomer concentration, which accelerates the subsequent growth process of nanocrystals, leading to the formation of the starlike nanocrystals with larger size (ca. 19-23 nm). They are further oriented to assemble reciprocally, gradually forming initial three-dimensional (3-D) "branched" nanoclusters (ca. 30-40 nm) to minimize the magnetostatic energy, owing to their size-dependent magnetic dipolar interaction. In addition, the surface-defect-induced secondary growth of the "branched" nanoclusters may considerably improve their uniformity, accompanied by the size increase in the presence of the monomers, resulting in the final "multibranched" nanoclusters with formation of sharp or obtuse edges (ca. 45-50 nm). Our study reveals the transformation of 0-D nanocrystals to 3-D nanoclusters as well as the shape evolution mechanism, which provide a versatile synthetic strategy for shape-controlled nanostructure. The multibranched nanoclusters have the higher magnetization and magnetically induced heating efficiency in an alternating current magnetic field, which can be used as promising heating agents for biomedical application. © 2013 American Chemical Society.

Ye H.-Y.,Nanjing Southeast University | Li S.-H.,CAS Wuhan Institute of Physics and Mathematics | Zhang Y.,Nanjing Southeast University | Zhou L.,CAS Wuhan Institute of Physics and Mathematics | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

Many order-disorder-type phase transitions in molecule-based ferroelectrics are related to changes of molecular dynamics. If the molecular motions do not involve reorientations of dipole moments, their ordering fails to contribute directly to spontaneous electric polarization. For understanding ferroelectric mechanisms in these systems, it is important to clarify how such molecular dynamics changes induce structurally symmetry-breaking phase transitions and thus the appearance of spontaneous electric polarization. Systematic characterization of an [18]crown-6 based host-guest inclusion compound, [(DIPA)([18]crown-6)]BF4 (DIPA = 2,6-diisopropylanilinium), shows it is an excellent ferroelectric with a large dielectric anomaly, significant pyroelectricity, and SHG response, and rectangular polarizaiton-electric field hysterisis loops. By the combination of variable-temperature single-crystal structural determination and solid-state NMR observation, it is found that the slowing down of the rotation of the [18]crown-6 molecule and the tumbling of the BF4 anion causes the symmetry breaking, while the spontaneous polarization is induced by the relative displacement between the cationic and anionic sublattices. This investigation will contribute to a deeper understanding of the structure-property relationship in the emerging molecular ferroelectrics. © 2014 American Chemical Society.

Wang N.,Nanjing Southeast University | Ye W.,Nanjing Southeast University
Physical Review C - Nuclear Physics | Year: 2013

Based on the stochastic Langevin equation coupled with a statistical decay model, we study the effects of deformation on the accuracy of extracting saddle-to-scission friction (β) by analyzing prescission neutron yields measured in heavy compound nuclei 248Fm, 252Fm, 256Fm, and 251Es. It is shown that accounting for the effect can appreciably reduce the value of β needed to fit data, and a friction value of (11-13)×1021 s-1 is obtained. Furthermore, we find that at low energy the sensitivity of light charged particles (LCPs) to β almost disappears, but the sensitive dependence of neutrons and LCPs on friction is substantially enhanced with increasing excitation energy. Our findings suggest that to obtain precise information of saddle-to-scission nuclear dissipation with particle emission, besides taking into account deformation effects in theoretical calculations, in experiments it is best to populate heavy fissioning systems with high energy. © 2013 American Physical Society.

Hou J.-M.,Nanjing Southeast University
Physical Review Letters | Year: 2013

We study a two-dimensional fermionic square lattice, which supports the existence of a two-dimensional Weyl semimetal, quantum anomalous Hall effect, and 2π-flux topological semimetal in different parameter ranges. We show that the band degenerate points of the two-dimensional Weyl semimetal and 2π-flux topological semimetal are protected by two distinct novel hidden symmetries, which both correspond to antiunitary composite operations. When these hidden symmetries are broken, a gap opens between the conduction and valence bands, turning the system into a insulator. With appropriate parameters, a quantum anomalous Hall effect emerges. The degenerate point at the boundary between the quantum anomalous Hall insulator and trivial band insulator is also protected by the hidden symmetry. © 2013 American Physical Society.

Hong W.,Nanjing Southeast University
IEEE MTT-S International Microwave Symposium Digest | Year: 2011

In this paper, the history of millimeter wave and THz research and applications in China and the current projects supported by China government related to millimeter wave and THz communications are briefly reviewed, some typical achievements in millimeter wave and THz components, systems and integrated circuits from some universities and institutes in China are introduced. © 2011 IEEE.

Ma Q.,Lanzhou University | Mei Z.L.,Lanzhou University | Zhu S.K.,Lanzhou University | Jin T.Y.,Lanzhou University | Cui T.J.,Nanjing Southeast University
Physical Review Letters | Year: 2013

In recent years, invisibility cloaks have received a lot of attention and interest. These devices are generally classified into two types: passive and active. The design and realization of passive cloaks have been intensively studied using transformation optics and plasmonic approaches. However, active cloaks are still limited to theory and numerical simulations. Here, we present the first experiment on active cloaking and propose an active illusion for the Laplace equation. We make use of a resistor network to simulate a conducting medium. Then, we surround the central region with controlled sources to protect it from outside detection. We show that by dynamically changing the controlled sources, the protected region can be cloaked or disguised as different objects (illusion). Our measurement results agree very well with numerical simulations. Compared with the passive counterparts, the active cloaking and illusion devices do not need complicated metamaterials. They are flexible, in-line controllable, and adaptable to the environment. In addition to dc electricity, the proposed method can also be used for thermodynamics and other problems governed by the Laplace equation. © 2013 American Physical Society.

Xue P.,Nanjing Southeast University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2013

We evaluate the spin squeezing dynamics of N independent spin-1/2 particles with exchange symmetry. Each particle couples to an individual and identical reservoir. We study the time evolution of spin squeezing under the influence of different decoherence. The spin squeezing property vanishes with evolution time under Markovian decoherence, while it collapses quickly and revives under non-Markovian decoherence. As spin squeezing can be regarded as a witness of multipartite entanglement, our scheme shows the collapses and revivals of multipartite entanglement under the influence of non-Markovian decoherence. © 2013 Elsevier B.V.

Zhao Y.-L.,Nanjing Southeast University | Wang D.-Y.,Nanjing Southeast University
Oxidative Medicine and Cellular Longevity | Year: 2012

All organisms respond to environmental stresses (e.g., heavy metal, heat, UV irradiation, hyperoxia, food limitation, etc.) with coordinated adjustments in order to deal with the consequences and/or injuries caused by the severe stress. The nematode Caenorhabditis elegans often exerts adaptive responses if preconditioned with low concentrations of agents or stressor. In C. elegans, three types of adaptive responses can be formed: hormesis, cross-adaptation, and dietary restriction. Several factors influence the formation of adaptive responses in nematodes, and some mechanisms can explain their response formation. In particular, antioxidation system, heat-shock proteins, metallothioneins, glutathione, signaling transduction, and metabolic signals may play important roles in regulating the formation of adaptive responses. In this paper, we summarize the published evidence demonstrating that several types of adaptive responses have converged in C. elegans and discussed some possible alternative theories explaining the adaptive response control. © 2012 Y.-L. Zhao and D.-Y. Wang.

Zheng J.,Nanjing Southeast University
Oncology Letters | Year: 2012

Metabolic activities in normal cells rely primarily on mitochondrial oxidative phosphorylation (OXPHOS) to generate ATP for energy. Unlike in normal cells, glycolysis is enhanced and OXPHOS capacity is reduced in various cancer cells. It has long been believed that the glycolytic phenotype in cancer is due to a permanent impairment of mitochondrial OXPHOS, as proposed by Otto Warburg. This view is challenged by recent investigations which find that the function of mitochondrial OXPHOS in most cancers is intact. Aerobic glycolysis in many cancers is the combined result of various factors such as oncogenes, tumor suppressors, a hypoxic microenvironment, mtDNA mutations, genetic background and others. Understanding the features and complexity of the cancer energy metabolism will help to develop new approaches in early diagnosis and effectively target therapy of cancer.

Gao G.-H.,Nanjing Southeast University | Sun Z.-Z.,Nanjing Southeast University
Journal of Computational Physics | Year: 2011

In this paper, a compact finite difference scheme for the fractional sub-diffusion equations is derived. After a transformation of the original problem, the L1 discretization is applied for the time-fractional part and fourth-order accuracy compact approximation for the second-order space derivative. The unique solvability of the difference solution is discussed. The stability and convergence of the finite difference scheme in maximum norm are proved using the energy method, where a new inner product is introduced for the theoretical analysis. The technique is quite novel and different from previous analytical methods. Finally, a numerical example is provided to show the effectiveness and accuracy of the method. © 2010 Elsevier Inc.

Li L.,Nanjing Southeast University | Cao J.,Nanjing Southeast University
Neurocomputing | Year: 2011

In this paper, cluster synchronization problem is studied for an array of coupled stochastic delayed neural networks by using pinning control strategy. Based on the free matrix approach and stochastic analysis techniques, some sufficient criteria are derived to ensure cluster synchronization of the network model if a single linear or adaptive feedback controller is added to each cluster. Furthermore, two specific methods are given to achieve desired cluster synchronization pattern. Finally, a numerical example is provided to demonstrate the effectiveness of the obtained theoretical results. © 2010 Elsevier B.V.

Fu D.-W.,Nanjing Southeast University | Zhang W.,Nanjing Southeast University | Cai H.-L.,Nanjing Southeast University | Zhang Y.,Nanjing Southeast University | And 3 more authors.
Journal of the American Chemical Society | Year: 2011

Molecular motion is one of the structural foundations for the development of functional molecular materials such as artificial motors and molecular ferroelectrics. Herein, we show that pendulum-like motion of the terminal group of a molecule causes a ferroelectric phase transition. Complex 4-methoxyanilinium tetrafluoroborate-18-crown-6 ([C7H 10NO(18-crown-6)]+[BF4]-, 1) shows a second-order ferroelectric phase transition at 127 K, together with an abrupt dielectric anomaly, Debye-type relaxation behavior, and the symmetry breaking confirmed by temperature dependence of second harmonic generation effect. The origin of the polarization is due to the order-disorder transition of the pendulum-like motions of the terminal para-methyl group of the 4-methoxyanilinium guest cation; that is, the freezing of pendulum motion at low temperature forces significant orientational motions of the guest molecules and thus induces the formation of the ferroelectric phase. The supramolecular bola-like ferroelectric is distinct from the precedent ferroelectrics and will open a new avenue for the design of polar functional materials. © 2011 American Chemical Society.

Wu L.,Nanjing Southeast University | Zhang M.-L.,Nanjing Southeast University
Journal of Machine Learning Research | Year: 2013

The problem of multi-label classification has attracted great interests in the last decade. Multi-label classification refers to the problems where an example that is represented by a single instance can be assigned to more than one category. Until now, most of the researches on multi-label classification have focused on supervised settings whose assumption is that large amount of labeled training data is available. Unfortunately, labeling training example is expensive and time-consuming, especially when it has more than one label. However, in many cases abundant unlabeled data is easy to obtain. Current attempts toward exploiting unlabeled data for multi-label classification work under the transductive setting, which aim at making predictions on existing unlabeled data while can not generalize to new unseen data. In this paper, the problem of inductive semi-supervised multi-label classification is studied, where a new approach named iMLCU, i.e. inductive Multi-Label Classification with Unlabeled data, is proposed. We formulate the inductive semi-supervised multi-label learning as an optimization problem of learning linear models and ConCave Convex Procedure (CCCP) is applied to optimize the non-convex optimization problem. Empirical studies on twelve diversified real-word multi-label learning tasks clearly validate the superiority of iMLCU against the other well-established multi-label learning approaches. © 2013 L. Wu & M.-L. Zhang.

Yin Y.,Nanjing Southeast University | Zhang X.,Nanjing Southeast University
Building and Environment | Year: 2010

Liquid desiccant regeneration has important effect on performance of a liquid desiccant air conditioning system. Compared with conventional packed regenerator, internally heated regenerator is proposed to achieve better regeneration performance. This study emphasized on both regeneration rate and regeneration thermal efficiency to evaluate the performance of both regenerators. A validated heat and mass transfer model was used to analyse and compare the performance of internally heated and adiabatic regenerators. The results indicated that internally heated regenerator not only could increase the regenerate rate, but also could exhibit higher energy utilization efficiency. Different from adiabatic regenerator, internally heated regenerator can provide comparable regeneration efficiency and regeneration rate at low desiccant flow rate, so it should be a good alternative to avoid carryover of desiccant droplets. Higher air flow rate would result in a deduction of regeneration thermal efficiency although achieving higher regeneration rate. Suitable flow rate of the air should be considered carefully in liquid desiccant regeneration. The internally regenerator could have considerable prospect in liquid desiccant air conditioning application. © 2010 Elsevier Ltd.

Liu Q.,Nanjing Southeast University | Guo Z.,University of North Carolina at Chapel Hill | Wang J.,Chinese University of Hong Kong
Neural Networks | Year: 2012

In this paper, a one-layer recurrent neural network is proposed for solving pseudoconvex optimization problems subject to linear equality and bound constraints. Compared with the existing neural networks for optimization (e.g., the projection neural networks), the proposed neural network is capable of solving more general pseudoconvex optimization problems with equality and bound constraints. Moreover, it is capable of solving constrained fractional programming problems as a special case. The convergence of the state variables of the proposed neural network to achieve solution optimality is guaranteed as long as the designed parameters in the model are larger than the derived lower bounds. Numerical examples with simulation results illustrate the effectiveness and characteristics of the proposed neural network. In addition, an application for dynamic portfolio optimization is discussed. © 2011 Elsevier Ltd.

Liu X.,Nanjing Southeast University | Cao J.,Nanjing Southeast University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2010

Discontinuous dynamical systems, particularly neural networks with discontinuous activation functions, arise in a number of applications and have received considerable research attention in recent years. In this paper, the robust state estimation problem is investigated for uncertain neural networks with discontinuous activations and time-varying delays, where the neuron-dependent nonlinear disturbance on the network outputs are only assumed to satisfy the local Lipschitz condition. Based on the theory of differential inclusions and nonsmooth analysis, several criteria are presented to guarantee the existence of the desired robust state estimator for the discontinuous neural networks. It is shown that the design of the state estimator for such networks can be achieved by solving some linear matrix inequalities, which are dependent on the size of the time derivative of the time-varying delays. Finally, numerical examples are given to illustrate the theoretical results. © 2010 IEEE.

Liang J.,Nanjing Southeast University | Wang Z.,Brunel University | Liu X.,Nanjing Southeast University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2010

TakagiSugeno (T-S) fuzzy models, which are usually represented by a set of linear submodels, can be used to describe or approximate any complex nonlinear systems by fuzzily blending these subsystems, and so, significant research efforts have been devoted to the analysis of such models. This paper is concerned with the passivity and passification problems of the stochastic discrete-time T-S fuzzy systems with delay. We first propose the definition of passivity in the sense of expectation. Then, by utilizing the Lyapunov functional method, the stochastic analysis combined with the matrix inequality techniques, a sufficient condition in terms of linear matrix inequalities is presented, ensuring the passivity performance of the T-S fuzzy models. Finally, based on this criterion, state feedback controller is designed, and several criteria are obtained to make the closed-loop system passive in the sense of expectation. The results acquired in this paper are delay dependent in the sense that they depend on not only the lower bound but also the upper bound of the time-varying delay. Numerical examples are also provided to demonstrate the effectiveness and feasibility of our criteria. © 2006 IEEE.

Wang H.-T.,Nanjing Southeast University | Wu G.,Nanjing Southeast University | Wu Z.-S.,Nanjing Southeast University
Journal of Composites for Construction | Year: 2014

The epoxy-bonded fiber-reinforced polymer (FRP) technique has been attracting more attention for repairing steel structures. In this paper, cracked steel plates repaired with FRP laminates were investigated with the finite element (FE) method. Three different FRP configurations designed with equivalent tensile stiffnesses were employed to repair cracked steel plates to determine the best FRP configuration for extending the crack growth life. The stress intensity factor (K) and the crack growth life of FRP-repaired specimens were compared, and the parameters influencing the repair effectiveness were analyzed. The results showed that FRP configurations have an obvious effect on K and the crack growth life. Configuration 1 was more effective than Configuration 2. The superiority of Configuration 1 over Configuration 2 was more evident with an increase of FRP thickness and/or initial crack length, but the superiority decreased with a thicker adhesive thickness and/or a larger local debond size. However, a comparison between Configuration 1 and Configuration 3 was highly dependent on FRP thickness, initial crack length, FRP width arranged in Configuration 3, and local debond size. Based on limited analyses of the three FRP configurations, FRP Configuration 1 is recommended for practical engineering applications when the fatigue cracks of steel members are similar to the center crack. Finally, two additional investigations were recommended for future study. © 2013 American Society of Civil Engineers.

Liu M.-L.,Nanjing Southeast University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

The asymmetric unit of the title compound, (C7H 10N)3[ZnCl4]Cl·0.5H2O, consists of three 3-methylanilinium cations, one tetrahedral tetrachloridozincate anion and one chloride anion and a water molecule, which lies on a twofold axis. The components are linked into chains parallel to the a axis by N - H⋯Cl hydrogen bonds. © Ming-Liang Liu 2011.

Liu M.-L.,Nanjing Southeast University
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

In the title salt, C8H6F3N2 +·ClO4 -, the atoms of the benzimidazole ring (including H atoms) are nearly coplanar (r.m.s. deviation of the fitted atoms = 0.0122 Å) and the triflouromethyl group lies out of this plane. The perchlorate anion adopts a distorted tetra-hedral conformation with the Cl - O bond distances ranging from 1.412 (3) to 1.439 (2) Å. The benzimidazolium cations are linked to adjacent anions by intermolecular N - H⋯O hydrogen bonds, forming chains. © Ming-Liang Liu 2011.

Jin C.-J.,Nanjing Southeast University | Wang W.,Nanjing Southeast University
Physica A: Statistical Mechanics and its Applications | Year: 2011

In this paper we study the congested patterns upstream of an isolated on-ramp in a cellular automaton traffic flow model, which is proposed in our previous paper [Cheng-Jie Jin, Wei Wang, Rui Jiang, Kun Gao, J. Stat. Mech (2010) P03018]. The simulation results under open boundary conditions are presented by spatiotemporal diagrams. Our diagram of congested patterns is quite similar to that of the cellular automaton models within Kerner's three-phase traffic theory, while some differences in the "moving synchronized flow pattern" (MSP) should be noted. In our model the upstream front of MSP propagates not only upstream, but also downstream. The propagation direction depends on the flow rates and densities of free flow and synchronized flow. Besides, in our model the outflow of wide moving jams or bottlenecks could be free flow or synchronized flow, as reported in many empirical data. In the dissolving of congestions, the form of free flow may be hindered and stable synchronized flow may emerge. This phenomenon can help us understand more about the outflow. All the interesting characteristics of our model are due to the nonmonotonic structure of synchronized flow branch in the fundamental diagram, which has not been found in previous models. © 2011 Elsevier B.V. All rights reserved.

Xu M.,Nanjing Southeast University | Sheng C.,Nanjing Southeast University
Energy and Fuels | Year: 2012

The present work was addressed to understand the contributions of the heat-treatment temperature and inorganic catalysis to the combustion characteristics of biochar. A cornstalk sample was leached by water and HCl to partially and fully remove active inorganic elements, respectively. The raw and leached samples were heat-treated at the temperatures of 200-900 °C. The resulting biochars were subjected to X-ray diffractometry and Raman spectroscopy analyses for structural characterization and thermogravimetric analysis for combustion characteristics, particularly, for char reactivity. It was found that the heat-treatment temperature has a significant effect on the evolution of the biochar structure, while inorganic matter has little influence. For low-temperature (200-400 °C) biochars, the heat-treatment temperature has a considerable influence on the devolatilizaiton and a marginal effect on char combustion behaviors, while the inorganic species, particularly, water-soluble species, have considerable influence on the behaviors of both stages. For high-temperature (500-900 °C) biochars, the heat-treatment temperature and inorganic matter are both important to char reactivity. The high contents of inorganic species of cornstalk resulted in the catalytic effect of inorganic species dominating over the influence of the carbonaceous structure ordering on char reactivity. With active inorganic species removed by leaching, char reactivity of biochars turned to decreasing monotonically with an increase of the treatment temperature. © 2011 American Chemical Society.

Wang G.,Nanjing Southeast University | Shen L.,Nanjing Southeast University | Sheng C.,Nanjing Southeast University
Energy and Fuels | Year: 2012

The paper presents the results of systematically characterizing the bottom and fly ash from a typical water-cooled vibrating grate furnace and the fly ash from a circulating fluidized-bed (CFB) combustor of two power plants burning similar mixed agricultural residues. Multi-standard techniques were employed in the characterization in terms of basic properties, particle morphology, chemical composition, mineralogy, and leaching behaviors. It was found that, despite the similar elemental compositions, the basic properties, particle morphology, mineralogical composition, and leaching behaviors were quite different between the three ashes mainly because of the differences in combustion conditions and, consequently, ash formation behaviors. The characterization indicated that the grate furnace bottom ash and CFB fly ash have potential for agricultural use with proper handling, while the grate furnace fly ash is currently problematic for use on agricultural purposes as well as building material. The obtained data and implications of this study are valuable for evaluating ash quality and developing sustainable utilization and management of the ashes from power plants firing mixed agricultural biomass. © 2011 American Chemical Society.

Qu M.,Purdue University | Abdelaziz O.,Oak Ridge National Laboratory | Yin H.,Nanjing Southeast University
Energy Conversion and Management | Year: 2014

Conventional natural gas-fired boilers exhaust flue gas direct to the atmosphere at 150-200 °C, which, at such temperatures, contains large amount of energy and results in relatively low thermal efficiency ranging from 70% to 80%. Although condensing boilers for recovering the heat in the flue gas have been developed over the past 40 years, their present market share is still less than 25%. The major reason for this relatively slow acceptance is the limited improvement in the thermal efficiency of condensing boilers. In the condensing boiler, the temperature of the hot water return at the range of 50-60 °C, which is used to cool the flue gas, is very close to the dew point of the water vapor in the flue gas. Therefore, the latent heat, the majority of the waste heat in the flue gas, which is contained in the water vapor, cannot be recovered. This paper presents a new approach to improve boiler thermal efficiency by integrating absorption heat pumps with natural gas boilers for waste heat recovery (HRAHP). Three configurations of HRAHPs are introduced and discussed. The three configurations are modeled in detail to illustrate the significant thermal efficiency improvement they attain. Further, for conceptual proof and validation, an existing hot water-driven absorption chiller is operated as a heat pump at operating conditions similar to one of the devised configurations. An overall system performance and economic analysis are provided for decision-making and as evidence of the potential benefits. These three configurations of HRAHP provide a pathway to achieving realistic high-efficiency natural gas boilers for applications with process fluid return temperatures higher than or close to the dew point of the water vapor in the flue gas. © 2014 Elsevier Ltd. All rights reserved.

Hao Q.,Nanjing Southeast University | Qiu T.,Nanjing Southeast University | Qiu T.,City University of Hong Kong | Chu P.K.,City University of Hong Kong
Progress in Surface Science | Year: 2012

The novel and burgeoning technique of surfaced-enhanced cellular fluorescence imaging has tremendous potential in the monitoring and investigation of intracellular processes at the single-molecular level, for instance, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics. The success hinges on the development and fabrication of plasmonic nanostructured surfaces with size and shape compatible with cell interactions because they are crucial to enhanced cellular imaging. In this review, the mechanism of surface-enhanced cellular fluorescence imaging is discussed in view of metal-enhanced fluorescence. The design of nanostructured surfaces with evenly distributed plasmonic fields suitable for enhanced cellular fluorescence imaging such as nanoparticle superlattice coatings, lithographically-based substrates, and alumina-templated surface are described. © 2012 Elsevier Ltd. All rights reserved.

Wang X.,Nanjing Southeast University | Wu Z.,Nanjing Southeast University | Wu Z.,Ibaraki University
Composite Structures | Year: 2010

This paper evaluates the safety factors, the applicable lengths, and relative cost of FRP (fiber reinforced polymer) and hybrid FRP cables that are potentially suitable for cable-stayed bridges with a super long-span of between 1000m and 10,000m. Following previous studies on 1000-m scale cable-stayed bridges with FRP cables, two kinds of hybrid FRP cables - the previously discussed hybrid basalt and carbon FRP (B/CFRP) cable and the newly-developed basalt and steel-wire FRP (B/SFRP) cable - as well as conventional steel cable, CFRP cable, and BFRP cable are further investigated focusing on their promise in meeting potential requirements for super long-span bridges. Some major results are as follows: (1) a three-stage model for determining safety factors of cables with different kinds and lengths is proposed; (2) a threshold of λ2 is suggested to achieve both high material and stiffness utilization efficiency, based on which the applicable lengths for different kinds of cables were evaluated; and (3) hybrid B/SFRP cables and BFRP cables are comparable in cost to steel cables within a 3000m span, while hybrid B/CFRP cables and CFRP cables demonstrate a superior performance/cost ratio over a longer span. © 2010 Elsevier Ltd.

He Z.-Q.,Nanjing Southeast University | Liu Z.,Nanjing Southeast University
Journal of Structural Engineering | Year: 2010

A unified methodology is proposed to compute the tendon stresses in externally prestressed beams in elastic and ultimate states, and practical design equations are developed to predict the ultimate tendon stresses. Previous test results have shown that there is an almost linear relationship between the tendon stress increment and the beam midspan deflection in both elastic and inelastic ranges. The key point is to seek this relationship and then the prediction of the tendon stress increment is transferred to the problem of calculating the beam midspan deflection. The second-order effect of external tendons is included in this deformation compatibility based analysis. Moreover, reasonable simplifications are made to establish practical design equations for the prediction of the ultimate tendon stress. The proposed equations are shown to be able to account for most of the important variables and result in good agreement with test data. It is shown that the ultimate stress increment is mainly dependent on the tendon eccentricity and the neutral axis depth, and the second-order effect can be reasonably taken into account using the stress and depth reduction factors. © 2010 ASCE.

Zhao Y.,Nanjing Southeast University | Xie Z.,Nanjing Southeast University | Gu H.,Nanjing Southeast University | Zhu C.,Nanjing Southeast University | Gu Z.,Nanjing Southeast University
Chemical Society Reviews | Year: 2012

Natural structural color materials, especially those that can undergo reversible changes, are attracting increasing interest in a wide variety of research fields. Inspired by the natural creatures, many elaborately nanostructured photonic materials with variable structural colors were developed. These materials have found important applications in switches, display devices, sensors, and so on. In this critical review, we will provide up-to-date research concerning the natural and bio-inspired photonic materials with variable structural colors. After introducing the variable structural colors in natural creatures, we will focus on the studies of artificial variable structural color photonic materials, including their bio-inspired designs, fabrications and applications. The prospects for the future development of these fantastic variable structural color materials will also be presented. We believe this review will promote the communications among biology, bionics, chemistry, optical physics, and material science (196 references). © 2012 The Royal Society of Chemistry.

Qian S.Z.,Nanjing Southeast University | Zhou J.,Technical University of Delft | Schlangen E.,Technical University of Delft
Cement and Concrete Composites | Year: 2010

This paper investigates the self-healing behavior of Engineered Cementitious Composites (ECC) with focus on the influence of curing condition and precracking time. Four-point bending tests were used to precrack ECC beams at different age, followed by different curing conditions, including air curing, 3% CO2 concentration curing, cyclic wet/dry (dry under 3% CO 2 concentration) curing and water curing. For all curing conditions, deflection capacity after self-healing can recover or even exceed that from virgin samples with almost all precracking ages. After self-healing, flexural stiffness was also retained significantly compared with that from virgin samples, even though the level of retaining decreases with the increase of precracking time. The flexural strength increases for samples pre-cracked at the age of 14 days and 28 days, presumably due to continuous hydration of cementitious materials afterwards. Furthermore, it is promising to utilize nanoclay as distributed internal water reservoirs to promote self-healing behavior within ECC without relying on external water supply. © 2010 Elsevier Ltd. All rights reserved.

Lin J.R.,Nanjing Southeast University
Acta Crystallographica Section E: Structure Reports Online | Year: 2010

In the title salt, C8H9N2+·C7H7O3S -·H2O, the dihedral angle between the cation and anion benzene rings is 50.1 (4)°. In the cation, the Cyanomethyl group is twisted from the plane of the benzene ring [C-C-C-N =-86 (12)°]. In the crystal, the cations, anions and water molecules are linked by N-H⋯O and O-H⋯O hydrogen bonds, forming a chain along the c axis.

Xu J.,Nanjing Southeast University | Li X.,Nanjing Southeast University | Sun F.,Nanjing Southeast University
Acta Biomaterialia | Year: 2010

Poly(2-hydroxyethyl methacrylate) hydrogels containing β-cyclodextrin (pHEMA/β-CD) have been investigated as a platform for sustained release of ophthalmic drugs. First of all, pHEMA/β-CD hydrogel membranes and contact lenses were prepared by photopolymerization of HEMA, mono-methacrylated β-CD (mono-MA-β-CD) and trimethylolpropane trimethacrylate using a cast molding process. The hydrogels were characterized by Fourier transform infrared spectroscopy, equilibrium swelling ratio (ESR) and tensile tester. The results showed that the incorporation of β-CD in the hydrogels increased the ESR and tensile strength. Then, puerarin was used as a model to evaluate drug loading and in vitro and in vivo release behavior of the pHEMA/β-CD hydrogels. It was revealed that puerarin loading and in vitro release rate were dependent on β-CD content in the pHEMA/β-CD hydrogels. In rabbit eyes the pHEMA/β-CD hydrogel contact lenses exhibited longer mean residence times (MRTF) of puerarin in tear fluid than that of pHEMA contact lenses and 1% puerarin eye drops. The puerarin concentration in the aqueous humor of rabbit reached a maximum of 0.81 μg ml-1 after wearing the pHEMA/β-CD contact lens, which had been presoaked in 0.802 mg ml-1 puerarin solution for 4.81 h. Also, the pHEMA/β-CD contact lenses had a higher drug bioavailability in aqueous humor than puerarin eye drops. The data demonstrate that pHEMA/β-CD hydrogel contact lenses can effectively deliver puerarin through the cornea. © 2009 Acta Materialia Inc.

Jiang X.,Nanjing Southeast University | Ellis N.,University of British Columbia
Energy and Fuels | Year: 2010

Storage properties and thermal stability of fuels are important background information when dealing with a new potential fuel. Following the first paper on the preparation and characterization of the fuel mixture produced through emulsification of bio-oil and biodiesel, the second part of this investigation reports on the storage and thermal stability of the bio-oil/biodiesel mixture. The physicochemical properties of the samples stored at different temperatures (60 and 80 °C) for up to 180 h are measured. Fuel properties, such as viscosity, water content, acid number, and average molecular weight of the bio-oil/biodiesel mixture, are measured before and after aging. In contrast to the aging properties of bio-oil alone, very little changes in water content and viscosity are shown for the mixtures aged at 80 °C for 180 h. Overall, a slight decrease in acid numbers is observed for the aged mixtures. Chemical changes are characterized using gel permeation chromatography (GPC), showing a slight increase in the molecular weight over time, possibly because of some polymerization and condensation reactions during storage. Further confirmation of the changes is shown through a Fourier transform infrared spectrometer (FTIR), thermal decomposition analysis using a thermogravimetric analyzer (TGA), and proton assignment using proton nuclear magnetic residence (1H NMR) spectroscopy. Finally, the study indicates that the bio-oil/biodiesel mixture is stable within the conditions tested as a fuel. © 2010 American Chemical Society.

Lu W.B.,Nanjing Southeast University | Zhu W.,Nanjing Southeast University | Xu H.J.,Nanjing Southeast University | Ni Z.H.,Nanjing Southeast University | And 2 more authors.
Optics Express | Year: 2013

The flexible control of surface plasmon polaritons (SPPs) is important and intriguing due to its wide application in novel plasmonic devices. Transformation optics (TO) offers the capability either to confine the SPP propagation on rigid curved/uneven surfaces, or to control the flow of SPPs on planar surfaces. However, TO has not permitted us to confine, manipulate, and control SPP waves on flexible curved surfaces. Here, we propose to confine and freely control flexible SPPs using TO and graphene. We show that SPP waves can be naturally confined and propagate on curved or uneven graphene surfaces with little bending and radiation losses, and the confined SPPs are further manipulated and controlled using TO. Flexible plasmonic devices are presented, including the bending waveguides, wave splitter, and Luneburg lens on curved surfaces. Together with the intrinsic flexibility, graphene can be served as a good platform for flexible transformation plasmonics. © 2013 Optical Society of America.

Wan X.,Nanjing Southeast University | Shen X.P.,Nanjing Southeast University
Optics Express | Year: 2013

We analyze and experimentally realize coplanar imaging of transverse-electric (TE) modes surface waves using weakly anisotropic metasurface consisting of non-periodic subwavelength U-shaped metallic structures. Such metallic structures with the exciting coplanar dipole are integrated on the top surface of a thin dielectric board. A circuit model is utilized to analyze the characteristics of the surface waves supported by the metasurface. By varying the geometrical parameters of the U-shaped metallic structures, the phases of surface waves are modulated, from which a planar lens is presented for the TE-mode coplanar imaging. The analyses and measurements show that anisotropies of the U-shaped metallic structures have little influence on the imaging properties of the planar lens. The measurement results have good agreements to numerical simulations. © 2013 Optical Society of America.

Li S.,Nanjing Southeast University
Advances in Complex Systems | Year: 2011

This paper develops an analytical model of contagion risk in banking systems with tiered structure. It explores the respective effects of banking network structure and bank activity on contagion risk in banking network evolution. The findings suggest that increasing interbank connections is conducive to handling banking crisis and reducing the effect of contagion risk, but its positive effect is limited; raising bank reserve ratio will enhance the stability of individual banks to a certain extent, but it may immediately lead to liquidity problems for banks that have less excess reserves, causing the occurrence of contagion risk; an excessive drive for risk assets with high return may bring high risk to banks and lead to instability of banking systems; the bank risk preference is crucial to the stability of banking systems, and the radicalness of it may lead to greater systemic instability. © 2011 World Scientific Publishing Company.

Chen J.,Nanjing Southeast University | Liu B.,Nanjing Southeast University
Inorganic Chemistry Communications | Year: 2012

Two new complexes, namely, Co(IDC)(phen) (1) and [Co(PrIDC)(phen)] n·nH 2O (2) (H 3IDC = 4,5- imidazoledicarboxylic acid, H 3PrIDC = 2-propyl-1H-imidazole-4,5- dicarboxylic acid, and phen = 1,10-phenanthroline) have been hydrothermally synthesized and structurally characterized. Complex 1 crystallizes in a tetranuclear fashion with a square ring-like structure. Complex 2 shows an infinite one-dimensional chain structure, in which the six-coordinated Co 3+ exhibits distorted octahedral geometry. It is particularly worth noting that the existence of the substitute group of 2-position in the 4,5-imidazoledicarboxylate ligand plays a critical role in the formation of the resulting diverse topological structures. The fluorescence properties of complexes 1 and 2 in the solid state have also been investigated. © 2012 Elsevier B.V. All rights reserved.

Wang Z.,Nanjing Southeast University | Wu B.,Ryerson University | Xu D.,Ryerson University | Zargari N.R.,Rockwell Automation
IEEE Transactions on Power Electronics | Year: 2011

In this paper, a hybrid pulsewidth modulation (PWM) scheme is proposed to suppress the LC resonance for the high-power current-source inverter (CSI) fed drives with low switching frequency. In CSI drive systems, the selective harmonic elimination (SHE) is selected due to the better performance of harmonics, but the LC resonance cannot be effectively damped due to the lack of control flexibility of SHE. In this paper, SHE is only used for the steady-state operation. The modulation scheme is then switched to space vector modulation with dynamic capacitor voltage control when the transient event occurs. The smoothed transitions between different modulation schemes are proposed. The proposed hybrid method effectively solves the resonant issues in CSI drives, while maintaining the power quality. Both simulation and experiments verify the performance of the proposed hybrid PWM scheme. © 2006 IEEE.

Wei J.,Nanjing Southeast University | Wei J.,State University of New York at Buffalo | Liu W.,State University of New York at Buffalo | Yan Z.,State University of New York at Buffalo
Journal of Biological Chemistry | Year: 2010

Accumulating evidence suggests that glycogen synthase kinase 3 (GSK-3) is a multifunctional kinase implicated in neuronal development, mood stabilization, and neurodegeneration. However, the synaptic actions of GSK-3 are largely unknown. In this study, we examined the impact of GSK-3 on AMPA receptor (AMPAR) channels, the major mediator of excitatory transmission, in cortical neurons. Application of GSK-3 inhibitors or knockdown of GSK-3 caused a significant reduction of the amplitude of miniature excitatory postsynaptic current (mEPSC), a readout of the unitary strength of synaptic AMPARs. Treatment with GSK-3 inhibitors also decreased surface and synaptic GluR1 clusters on dendrites and increased internalized GluR1 in cortical cultures. Rab5, the small GTPase controlling the transport from plasma membrane to early endosomes, was activated by GSK-3 inhibitors. Knockdown of Rab5 prevented GSK-3 inhibitors from regulating mEPSC amplitude. Guanyl nucleotide dissociation inhibitor (GDI), which regulates the cycle of Rab5 between membrane and cytosol, formed an increased complex with Rab5 after treatment with GSK-3 inhibitors. Blocking the function of GDI occluded the effect of GSK-3 inhibitors on mEPSC amplitude. In cells transfected with the non-phosphorylatable GDI mutant, GDI(S45A), GSK-3 inhibitors lost the capability to regulate GDI-Rab5 complex, mEPSC amplitude, and AMPAR surface expression. These results suggest that GSK-3, via altering the GDI-Rab5 complex, regulates Rab5-mediated endocytosis of AMPARs. It provides a potential mechanism underlying the role of GSK-3 in synaptic transmission and plasticity. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

Cheng Y.J.,University of Electronic Science and Technology of China | Hong W.,Nanjing Southeast University | Wu K.,University of Montréal | Fan Y.,University of Electronic Science and Technology of China
IEEE Transactions on Antennas and Propagation | Year: 2011

Two types of substrate integrated waveguide (SIW) long slot leaky-wave antennas with controllable sidelobe level are proposed and demonstrated in this paper. The first prototype is able to achieve an excellent sidelobe level of -27.7 dB by properly meandering a long slot etched on the broadside of a straight SIW section from the centerline toward the sidewall then back. But it is known that an asymmetrically curved slot would worsen the cross-polar level. To overcome this drawback, a modified leaky-wave antenna is proposed, which has a straight long slot etched on the broadside of a meandering SIW section. It yields an outstanding sidelobe level of -29.3 dB and also improves the cross-polar level by more than 11 dB at 35 GHz. Experimental results agree well with simulations, thus validating our design. Then, a two-dimensional (2-D) multibeam antenna is developed by combining such 14 leaky-wave antennas with an SIW beamforming network (BFN). It has features of scanning both in elevation orientation by varying frequency and in cross-plane direction by using the BFN. Excited at ports 110 of such a 2-D multibeam antenna at 35 GHz, angular region of 86.6° in azimuth can effectively be covered by 3 dB beam-width of ten pencil beams. Varying frequency from 33 GHz to 37 GHz, the angular region of 37.5° and 38.9° in elevation can be covered by 3 dB beam-width of those continuous scanning beams excited at ports 6 and 8 respectively. © 2006 IEEE.

Zeng H.,Nanjing Southeast University | Zeng H.,Hong Kong Baptist University | Cheung Y.-M.,Hong Kong Baptist University
IEEE Transactions on Knowledge and Data Engineering | Year: 2012

The pairwise constraints specifying whether a pair of samples should be grouped together or not have been successfully incorporated into the conventional clustering methods such as k-means and spectral clustering for the performance enhancement. Nevertheless, the issue of pairwise constraints has not been well studied in the recently proposed maximum margin clustering (MMC), which extends the maximum margin framework in supervised learning for clustering and often shows a promising performance. This paper therefore proposes a pairwise constrained MMC algorithm. Based on the maximum margin idea in MMC, we propose a set of effective loss functions for discouraging the violation of given pairwise constraints. For the resulting optimization problem, we show that the original nonconvex problem in our approach can be decomposed into a sequence of convex quadratic program problems via constrained concave-convex procedure (CCCP). Subsequently, we present an efficient subgradient projection optimization method to solve each convex problem in the CCCP sequence. Experiments on a number of real-world data sets show that the proposed constrained MMC algorithm is scalable and outperforms the existing constrained MMC approach as well as the typical semi-supervised clustering counterparts. © 1989-2012 IEEE.

Min X.,Nanjing Southeast University | Jiang S.,Nanjing Southeast University
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2011

The feed drive system is a major heat source of machine tools, which results in considerable thermal drift at the tool. Therefore, there is a need to establish a scientific and systematic model that can be used to predict the temperature distribution of the feed drive system. In this research, considering the thermal contact resistance between the bearing and its housing, an integrated thermal model has been developed by the aid of the finite-element method to analyse the temperature distribution of a ball screw feed drive system, in particular the theoretical determination of power losses caused by the friction in ball screw pair, rolling bearings, and guide ways. Thermal boundary conditions including the convective heat transfer coefficients and heat flux have been obtained using the Fourier's law. Results reveal that the ball screw shaft surface has a uniform temperature rise of 4.2 °C under a given condition. The temperature rise agrees with the data obtained by an infrared thermometer.

Xu O.,Nanjing Southeast University
Progress in Electromagnetics Research | Year: 2011

The dielectric pyramid loaded and the dielectric cone loaded diagonal horn working at 150 GHz are investigated by using Gaussian beam mode analysis. With extremely low cross-polarized and axially symmetrical field distribution in the horn aperture, the calculated fundamental Gaussian mode coupling achieves about 98%. The far field radiation patterns of the two antennas are analyzed using fundamental Gaussian mode aperture field distribution model whose results agree with high-accuracy CST TM software computations, indicating that the dielectric loaded horns radiate fine Gaussian beams. The dielectric loaded geometry may be used to modify the diagonal horns with distorted beam.

Jin X.,Nanjing Southeast University | Zhang X.,Nanjing Southeast University
Applied Thermal Engineering | Year: 2011

Phase change materials (PCMs) can be used to shift the cooling or heating load from the peak period to the off-peak period. In this paper, a new double layer phase change material (PCM) floor is put forward. The two layers of PCM have different melting temperature. The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. According to the numerical model built in this paper, the thermal performances of the floor are analyzed. The results show that the optimal melting temperatures of PCMs exist. The fluctuations of the floor surface temperatures and the heat fluxes will be reduced and the system still can provide a certain amount of heat or cold energy after the heat pump or chiller has been turned off for a long time. Compared to the floor without PCM, the energy released by the floor with PCM in peak period will be increased by 41.1% and 37.9% during heating and cooling when the heat of fusion of PCM is 150 kJ/kg. © 2011 Elsevier Ltd. All rights reserved.

Peng D.,Nanchang University | Zhang X.,Nanjing Southeast University
Applied Energy | Year: 2011

Solar collector/regenerator (C/R) using liquid desiccant combines solar photothermic transformation and regeneration of liquid desiccant together, effectively achieving the regeneration for solar energy-driven liquid desiccant cooling systems. In this paper a group of dimensionless heat and mass transfer equations describing the heat and mass transfer process in the solar C/R were obtained by introducing total temperature difference (ΔT0) and dimensionless heat loss coefficient (hz). For the sake of predicting the heat loss of air stream and simplifying calculation, the models of dimensionless air temperature (θa) and equilibrium humidity ratio (YeL) along with the height of solar C/R were put forward. An analytical solution was formed by two differential equations on the dimensionless heat and mass transfer driving potentials and the heat and mass conservation equations. Compared with the numerical simulation results, the analytical results on the outlet parameters of solar C/R have great precision with different Lewis factor Le, total temperature difference ΔT0 and air-to salt mass flow rate ratio ASMR. Simultaneously, the effects of above variables on the regeneration performance were analyzed. Lastly, by comparing with the experimental data, the analytical calculation results can agree well with the experimental results validating the analytical model is an ideal way for predicting the performance of the solar C/R. © 2011 Elsevier Ltd.

Peng D.,Nanchang University | Zhang X.,Nanjing Southeast University
Energy | Year: 2011

Solar liquid collector/regenerator combines solar photothermic transformation and liquid regeneration together for solar energy-driven liquid desiccant cooling systems. A group of dimensionless heat and mass transfer equations describing the heat and mass transfer process in the solar C/R(Collector/Regenerator) were obtained by introducing total temperature difference (ΔT0) and dimensionless heat loss coefficient (hz). The increment of solution concentration ΔC was increased 2.9-3.5%/°C and 5.3%/°C for increasing unit inlet temperature of air stream and solution respectively and increased about 6.2%/(g/kg) and 0.9%/(g/kg) for decreasing unit inlet humidity ratio of air and solution concentration. Besides, the increasing number of heat transfer units (NTU), air-to-salt mass flow rate ratio (ASMR) and total temperature difference (ΔT0) can increase the performance of solution regeneration significantly. Compared to parallel flow regeneration, the performance of counterflow regeneration was increased about 10%. © 2011 Elsevier Ltd.

Liao Z.,Nanjing Southeast University | Pan B.C.,Nanjing Southeast University | Shen X.,Nanjing Southeast University | Cui T.J.,Nanjing Southeast University
Optics Express | Year: 2014

We present the occurrence of bright modes and dark modes in spoof localized surface plasmons (LSPs) generated by ultrathin corrugated metallic disks. As two such disks with asymmetric geometries are placed in close proximity, we find that dark modes (in multipoles) of one disk emerge by coupling with the bright modes (in dipoles) of the other disk. Then we further observe multiple Fano resonances due to destructive interferences of dark modes with the overlapping and broadened bright modes. These Fano line-shapes clearly exhibit the strong polarization dependence. We design and fabricate the ultrathin corrugated bi-disk structure in the microwave frequency, and the measurement results show reasonable agreement with theoretical predictions and numerical simulations. Such multiple Fano resonances could be exploited for the plasmonic devices at lower frequencies. © 2014 Optical Society of America.

Xue P.,Nanjing Southeast University | Sanders B.C.,University of Calgary
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We show that the standard quantum-walk quantum-to-classical transition, characterized by ballistic-to-diffusive spreading of the walker's position, can be controlled by externally modulating the coin state. We illustrate this by showing an oscillation between classical diffusive and quantum ballistic spreading using numerical and asymptotically exact closed-form solutions, and we prove that the walker is in a controllable incoherent mixture of classical and quantum walks with a reversible quantum-to-classical transition. © 2013 American Physical Society.

Mao W.,Nanjing Southeast University | Lu Z.,Nanjing Southeast University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We study the beam spin asymmetry ALUsinh in semi-inclusive π0 electroproduction contributed by the T-odd twist-3 distribution function g ⊥(x,kT2). We calculate this transverse momentum dependent distribution function for the u and d quarks inside the proton in a spectator model including the scalar and the axial-vector diquark components. Using the model results, we estimate the asymmetry ALUsinh in the ep→e′π0X process in which the lepton beam is longitudinally polarized. The model prediction is compared with the data measured by the CLAS and HERMES collaborations, and it is found that our numerical results agree with the experimental data reasonably. Especially, our results can well describe the CLAS data at the region where the Bjorken x and the pion transverse momentum is not large. We also make a prediction on the asymmetry ALUsinh in π0 electroproduction at CLAS12 using the same model calculation. © 2013 American Physical Society.

Zhang X.,Nanjing Southeast University | Xu Z.,University of Sichuan
International Journal of Intelligent Systems | Year: 2014

Recently, a new model based on Pythagorean fuzzy set (PFS) has been presented to manage the uncertainty in real-world decision-making problems. PFS has much stronger ability than intuitionistic fuzzy set to model such uncertainty. In this paper, we define some novel operational laws of PFSs and discuss their desirable properties. For the multicriteria decision-making problems with PFSs, we propose an extended technique for order preference by similarity to ideal solution method to deal effectively with them. In this approach, we first propose a score function based comparison method to identify the Pythagorean fuzzy positive ideal solution and the Pythagorean fuzzy negative ideal solution. Then,we define a distancemeasure to calculate the distances between each alternative and the Pythagorean fuzzy positive ideal solution as well as the Pythagorean fuzzy negative ideal solution, respectively. Afterward, a revised closeness is introduced to identify the optimal alternative. At length, a practical example is given to illustrate the developed method and to make a comparative analysis. © 2014 Wiley Periodicals, Inc.

Zhang C.,Nanjing Southeast University | Zhang C.,Nanjing Institute of Supervision and Testing on Product Quality
Food Control | Year: 2013

Techniques for species assay are potent tools for the supervision of meat adulteration. Matsunaga et al. have established a reliable multiplex PCR method to identify chicken, beef, pork and mutton species in meat products. However, this method was not sensitive enough in the assay of further-processed meats. Here, we attempted 2 strategies, semi-nested multiplex PCR and shortening primers, to enhance the sensitivity of multiplex PCR. As the semi-nested multiplex PCR, first PCR was performed by a pair of common primers, and the product was used as the template of second multiplex PCR. This method lowered the limit of detection (LOD) of multiplex PCR by 3 orders of magnitude, and effectively identified meat species in further-processed foods. The LOD of semi-nested multiplex PCR reached 1 pg of DNA per reaction, which was 10-fold lower than a standardized Real-time PCR method. In contrast, multiplex PCR using truncated primers could hardly meet identical efficiency on different templates, and failed to improve the method sensitivity. The semi-nested multiplex PCR established in this study would be practical in the control of meat adulteration, and could benefit QC of meat manufacture. © 2012 Elsevier Ltd.

Fan L.,University of South Florida | Zhu C.,Nanjing Southeast University | Miao Z.,University of South Florida | Hu M.,Nanjing Southeast University
IEEE Transactions on Energy Conversion | Year: 2011

Interests of subsynchronous resonance (SSR) in series compensated electric networks with wind power penetration have arisen recently. To better understand the nature of such systems, modal analysis of a doubly-fed induction generator (DFIG)-based wind energy system interconnected with a series compensated electric network is conducted in this paper. The system model is built in Matlab/Simulink. The major contributions of the paper include: 1) identification of the four system modes (SSR, supersynchronous, electromechanical, and shaft modes) of a DFIG-based wind farm interfaced with a series compensated network, 2) investigation of the impacts of various parameters and operating conditions on those modes, and 3) prediction of the dynamic performance of the system using modal analysis and confirmation of such prediction via time-domain simulation results. © 2011 IEEE.

Ji Y.,Nanjing Southeast University | Qian Y.,Nanjing Southeast University
RSC Advances | Year: 2014

The dendrimer PNS-G0 with Schiff-base imines (CN) realizes highly selective and common fluorescence (λex = 400 nm) or up-converted fluorescence (λex = 800 nm) turn-on effect to qualitatively and quantitatively detect zinc ions (Zn2+). The PNS-G0 + Zn 2+ complex (CN-Zn-O) fluorescence emitting parts were firstly proposed as half-organic quantum dots (HOQDs). The HOQDs probe PNS-G0 for Zn2+ by the coordination method based on imine isomerization (inhibition) mechanism, which has potential applications in biological imaging, analytical chemistry, and optical physics areas. © the Partner Organisations 2014.

Hu J.,Nanjing Southeast University | Xiao R.,Nanjing Southeast University | Shen D.,Nanjing Southeast University | Zhang H.,Nanjing Southeast University
Bioresource Technology | Year: 2013

Structural characteristics of benzene-ethanol-extracted lignin (BEL) and acetone-extracted lignin (AL) precipitated from black liquor were identified by elemental analysis, FTIR, 13C NMR, and 1H NMR, while the thermal behaviors were examined with thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR). The frequency of β-O-4 bonds per 100 C9 monomeric units was 28 and 17 for BEL and AL. Two-stage pyrolysis processes were observed for the two lignins. The mass loss rate of the initial solvent evolution stage (110-180°C) of BEL was greater than that of AL. The two lignins presented slightly different mass loss curves and evolution profiles of gases in the main pyrolysis stage (280-500°C). A global kinetic model was proposed for lignin pyrolysis and activation energies of 39.5 and 38.8kJ/mol was obtained for BEL and AL. The results enhance understanding of lignin pyrolysis and facilitate commercial utilization of black-liquor lignin. © 2012 Elsevier Ltd.

Wu D.-H.,Nanjing Southeast University | Jin L.,Nanjing Southeast University
Inorganic Chemistry Communications | Year: 2012

Bis(triethylbenzylammonium) tetrachlorocobaltate(II), (C 13H 22N +) 2·CoCl 4 2- was synthesized and separated as blue block crystals. DSC measurement detected that this compound undergoes a reversible phase transition at ca. 336 K with a hysteresis of 10 K. Dielectric measurements confirm the transition at ca. 336 K. The crystal structures determined at 291(2) K (a = 16.72 Å, b = 9.32 Å, c = 20.36 Å, β = 106.90°, V = 3035.1 Å 3, Z = 4) and 353(2) K (a = 20.16 Å, b = 9.35 Å, c = 34.29 Å, β = 108.61°, V = 6126.7 Å 3, Z = 8) show that the phase transition is a type of isostructural change with the same space group P2 1/c (No. 14). The most distinct difference between the two structures in high-temperature phase (HTP) and room-temperature phase (RTP) is the different molar ratios of configurations for the cations. The rotation of ethyl groups bonding with the N atom between the propeller-like configuration and butterfly-like configuration is probably the driving force to the phase transition. Non-classic hydrogen bonding effect on the transition was shown to be negligible. © 2012 Elsevier B.V.

Peng C.,Nanjing Southeast University | Huang Y.,Nanjing Southeast University | Wu Z.,Nanjing Southeast University
Energy and Buildings | Year: 2011

Building-Integrated Photovoltaics (BIPV) are one of the best ways to harness solar power, which is the most abundant, inexhaustible and clean of all the available energy resources. This paper discusses issues concerning BIPV in architectural design in China, including how to choose between BIPV and building-attached photovoltaics (BAPV), whether it is necessary for photovoltaic components to last as long as buildings and how to design BIPV structures. The paper shows that we should consider the function, cost, technology and aesthetics of BIPV, rather than solely the high integrations. According to developments in technology and markets, photovoltaic structures and design should be focused on the maintenance and replacement of photovoltaic cell modules, rather than simply prolonging their lives. To solve problems associated with the existing photovoltaic structures in China, we design a building photovoltaic structure that allows convenient maintenance and replacement of photovoltaic components. © 2011 Elsevier B.V.

Zhang Z.,Nanjing Southeast University | Liao X.,Nanjing Southeast University
Journal of Microelectromechanical Systems | Year: 2011

This letter presents research on a packaging-test-fixture for 8-10 GHz GaAs monolithic microwave integrated circuit-based in-line coupling radio frequency (RF) microelectromechanical systems (MEMS) power sensors by showing the performance of the power sensors embedded into RF circuit systems. The principle of the sensors is to measure a certain percentage of the microwave power coupled into a MEMS membrane. The packaging method utilizes the transition of the coplanar waveguide (CPW)-port power sensor, two microstrip lines, and two sub-miniature-A connectors. Experiments demonstrate that the design of the packaged power sensor has resulted in the reflection loss of about -25 dB at 9 GHz, with an insertion loss of less than 1.3 dB at 8-10 GHz, with good linearity of the output response. A sensitivity of more than 18.7 μV mW-1 is obtained at 9 GHz at ambient temperature. © 2006 IEEE.

Wang G.,Nanjing Southeast University
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011 - Proceedings | Year: 2011

Considering of the low income and shortage of computer in developing countries, many people have the idea of sharing technical resources. This paper describes a new kind of eye-controlled multi-mouse application based on OpenCV. By using the recent image recognition technology, the design of this paper only use the laptop's build-in camera or commonly used video camera to achieve eye-controlled mouse function. Attach with Microsoft's newly Multi-Point Mouse SDK, it can be easy to have the function of interference-free multi-mouse usage. It is easy to use, good reusability, and no need for any other external devices, good recognition performance. © 2011 IEEE.

Zheng D.,Nanjing Southeast University | Da F.,Nanjing Southeast University
Optics and Lasers in Engineering | Year: 2011

Branch cut method is a powerful noise-immune algorithm for correct phase unwrapping of noisy phase maps. The shortest branch cut length promises the optimal unwrapping result of the wrapped phase maps. A new algorithm is proposed to search for the shortest branch cut length by simple exchange operation. Although the algorithm is on the basis of stochastic search techniques, it has a high probability of finding the shortest branch cut length or an approximation of it. Compared with the traditional algorithms, the algorithm is fast and competitive. © 2011 Elsevier Ltd. All rights reserved.

Wu Q.,Nanjing Southeast University | Wu Q.,Hong Kong Polytechnic University
Expert Systems with Applications | Year: 2011

This paper presents a novel hybrid forecasting model based on support vector machine and particle swarm optimization with Cauchy mutation objective and decision-making variables. On the basis of the slow convergence of particle swarm algorithm (PSO) during parameters selection of support vector machine (SVM), the adaptive mutation operator based on the fitness function value and the iterative variable is also applied to inertia weight. Then, a hybrid PSO with adaptive and Cauchy mutation operator (ACPSO) is proposed. The results of application in regression estimation show the proposed hybrid model (ACPSO-SVM) is feasible and effective, and the comparison between the method proposed in this paper and other ones is also given, which proves this method is better than other methods. © 2011 Published by Elsevier Ltd.

Yang C.,Nanjing Southeast University | Xu C.,Nanjing Southeast University | Wang X.,Nanjing Southeast University
Langmuir | Year: 2012

Unique structured nanomaterials can facilitate the direct electron transfer between redox proteins and the electrodes. Here, in situ directed growth on an electrode of a ZnO/Cu nanocomposite was prepared by a simple corrosion approach, which enables robust mechanical adhesion and electrical contact between the nanostructured ZnO and the electrodes. This is great help to realize the direct electron transfer between the electrode surface and the redox protein. SEM images demonstrate that the morphology of the ZnO/Cu nanocomposite has a large specific surface area, which is favorable to immobilize the biomolecules and construct biosensors. Using glucose oxidase (GOx) as a model, this ZnO/Cu nanocomposite is employed for immobilization of GOx and the construction of the glucose biosensor. Direct electron transfer of GOx is achieved at ZnO/Cu nanocomposite with a high heterogeneous electron transfer rate constant of 0.67 ± 0.06 s -1. Such ZnO/Cu nanocomposite provides a good matrix for direct electrochemistry of enzymes and mediator-free enzymatic biosensors. © 2012 American Chemical Society.

Chen X.H.,Nanjing Southeast University | Wang D.W.,RWTH Aachen
Wear | Year: 2011

Studies are conducted to the characterization of the aggregate-surface texture in polishing process by fractal and spectral approaches based on rubber friction theory. The Wehner/Schulze (W/S) polishing machine is adopted to simulate the vehicle tyre polishing action. The commonly used aggregates in wearing courses named basalt, gabbros and greywacke are investigated. The surface profile texture and dynamic friction coefficient were monitored in polishing process. The dynamic friction coefficient was observed to reach a stable equilibrium phase after a sharp decrease at the initial polishing stage and the friction evolution in W/S polishing process can be described with power law. Fractal analysis reveals that the changes of amplitude and curve length of the profiles are the main contribution to the loss of friction. Spectral analysis reveals that the polishing action plays an important role in the changes of micro-texture. It can be concluded that the evolution of friction of the aggregates is primarily governed by micro-texture changes due to differential removal of mineral components. © 2011 Elsevier B.V.

Yang J.,Nanjing Southeast University | Chen W.-H.,Loughborough University | Li S.,Nanjing Southeast University
IET Control Theory and Applications | Year: 2011

Robust control of non-linear systems with disturbances and uncertainties is addressed in this study using disturbance observer-based control (DOBC) technique. In this framework, the 'disturbance' is a generalised concept, which may include external disturbances, unmodelled dynamics and system parameter perturbations. The existing DOBC methods were only applicable for the case where disturbances and uncertainties satisfy so-called matching condition, that is, they enter the system in the same channel as the control inputs. By appropriately designing a disturbance compensation gain vector in the composite control law, a non-linear disturbance observer-based robust control method is proposed in this study to attenuate the mismatched disturbances and the influence of parameter variations from system output channels. The proposed method is applied to a missile system with non-linear dynamics in the presence of various uncertainties and external disturbances. Simulation shows that, compared with the widely used non-linear dynamic inversion control (NDIC) and NDIC plus integral action methods, the proposed method provides much better disturbance attenuation ability and stronger robustness against various parameter variations. © 2011 The Institution of Engineering and Technology.

Ren J.,Nanjing Southeast University | Ren J.,Shangqiu Normal University | Sun Z.-Z.,Nanjing Southeast University | Zhao X.,Nanjing Southeast University
Journal of Computational Physics | Year: 2013

An effective finite difference scheme is considered for solving the time fractional sub-diffusion equation with Neumann boundary conditions. A difference scheme combining the compact difference approach the spatial discretization and L 1 approximation for the Caputo fractional derivative is proposed and analyzed. Although the spatial approximation order at the Neumann boundary is one order lower than that for interior mesh points, the unconditional stability and the global convergence order O(τ 2 - α + h 4) in discrete L 2 norm of the compact difference scheme are proved rigorously, where τ is the temporal grid size and h is the spatial grid size. Numerical experiments are included to support the theoretical results, and comparison with the related works are presented to show the effectiveness of our method. © 2012.

Sang X.,Nanjing Southeast University | Liu X.,Nanjing Southeast University
Fuzzy Sets and Systems | Year: 2014

An important issue in the theory of ordered weighted averaging (OWA) operators is the determination of the associated weights. One important approach, suggested by Wang, Luo and Liu in 2007 determines a special class of OWA operators with the least square deviation (LSD) of OWA weights for a given orness level. In this paper, using the method of Lagrange multipliers, we solve this constrained optimization problem analytically, and derive a polynomial equation to determine the optimal weighting vector. Numerical examples illustrate our proposed approach. © 2013 Elsevier B.V. All rights reserved.

Cong J.,Nanjing Southeast University | Yun B.,Nanjing Southeast University | Cui Y.,Nanjing Southeast University
Optics Express | Year: 2013

By introducing the frequency tuning sensitivity, an analytical model based on equivalent LC circuit is developed for the relative frequency tuning range of THz semiconductor split-ring resonator (SRR). And the model reveals that the relative tuning range is determined by the ratio of the kinetic inductance to the geometric inductance (RKG). The results show that under the same carrier density variation, a larger RKG results in a larger relative tuning range. Based on this model, a stacked SRR-dimer structure with larger RKG compared to the single SRR due to the inductive coupling is proposed, which improves the relative tuning range effectively. And the results obtained by the simple analytical model agree well with the numerical FDTD results. The presented analytical model is robust and can be used to analyze the relative frequency tuning of other tunable THz devices. ©2013 Optical Society of America.

Zhu B.,Nanjing Southeast University | Xu Z.,University of Sichuan
Fuzzy Sets and Systems | Year: 2014

The existing methods for solving the group decision making (GDM) problems with preference relations generally include four steps: (1) estimation of missing preferences, (2) consistency and consensus reaching, (3) aggregation and (4) exploitation, which make the GDM process complicated. Relatively, very few research results focus on exploring the methods which can simplify this process to improve the efficiency. In this paper, we develop a new fuzzy linear programming method (FLPM) to deal with the GDM problems with additive reciprocal fuzzy preference relations (FPRs). The FLPM can directly produce meaningful results without the four steps. An effect index is developed to measure the decision makers (DMs)' effects in the GDM problems. Based on the FLPM and the effect index, we propose a new method to determine the DMs' weights. A step by step procedure is further proposed to deal with the GDM problems with all the developed methods, and its performance is illustrated by examples. © 2014 Published by Elsevier B.V.

Zhang H.,Nanjing Southeast University
OncoTargets and Therapy | Year: 2016

Drug delivery system based on nanobiotechnology can improve the pharmacokinetics and therapeutic index of chemotherapeutic agents, which has revolutionized tumor therapy. Onivyde, also known as MM-398 or PEP02, is a nanoliposomal formulation of irinotecan which has demonstrated encouraging anticancer activity across a broad range of malignancies, including pancreatic cancer, esophago-gastric cancer, and colorectal cancer. This up-to-date review not only focuses on the structure, pharmacokinetics, and pharmacogenetics of Onivyde but also summarizes clinical trials and recommends Onivyde for patients with advanced solid tumors. © 2016 Zhang et al.

Zeng W.L.,Nanjing Southeast University | Lu X.B.,Nanjing Southeast University
Electronics Letters | Year: 2011

The non-local means (NLM) provides a useful tool for image denoising and many variations of the NLM method have been proposed. However, few works have tried to tackle the task of adaptively choosing the patch size according to region characteristics. Presented is a region-based NLM method for noise removal. The proposed method first analyses and classifies the image into several region types. According to the region type, a local window is adaptively adjusted to match the local property of a region. Experimental results show the effectiveness of the proposed method and demonstrate its superiority to the state-of-the-art methods. © 2011 The Institution of Engineering and Technology.

Pan L.,Nanjing Southeast University | Pan L.,Jia Ying University | Cao J.,Nanjing Southeast University
Nonlinear Analysis: Real World Applications | Year: 2011

In this paper, we discuss anti-periodic solution for delayed cellular neural networks with impulsive effects. By means of contraction mapping principle and Krasnoselski's fixed point theorem, we obtain the existence of anti-periodic solution for neural networks. By establishing a new impulsive differential inequality, using Lyapunov functions and inequality techniques, some new results for exponential stability of anti-periodic solution are obtained. Meanwhile, an example and numerical simulations are given to show that impulses may change the exponentially stable behavior of anti-periodic solution. © 2011 Elsevier Ltd. All rights reserved.

Gao D.,Nanjing Southeast University | Chen Z.,Nanjing Southeast University
International Journal of Thermal Sciences | Year: 2011

A thermal lattice Boltzmann model is developed for the melting with natural convection in porous media at the representative elementary volume scale. An evolution equation of the temperature distribution function is constructed through selecting the equilibrium distribution function and non-linear source term properly. Simulations of melting with natural convection in a cavity with and without a porous matrix are performed using the present model. Numerical results show good agreement with previous analytical, experimental and numerical solutions. In addition, the analysis of the melting process over a wider range of dimensionless parameters indicates that for conditions of high Darcy number and high porosity the effect of natural convection on the melting becomes stronger, and the Rayleigh number based on porous media (Ram) proposed in the previous studies may not be appropriate to correlate the average hot wall Nusselt number independently. The present model is also suitable for simulating freezing and solidification in porous media without modification. © 2010 Elsevier Masson SAS. All rights reserved.

Lin J.,Nanjing Southeast University | Fei S.,Nanjing Southeast University
Asian Journal of Control | Year: 2011

This paper is concerned with the reliable controller design problem for a class of singular systems with interval time-varying delay and norm-bounded uncertainties. A more practical model of actuator failures than outages is considered. First, by constructing a novel Lyapunov-Krasovskii functional combined with Finsler's Lemma, an improved delay-range-dependent stability criterion for the nominal unforced singular time-delay system is established in terms of linear matrix inequality (LMI). Then, based on this criterion, an LMI condition for the design of a reliable state feedback controller is presented such that, for all parameter uncertainties and actuator failures, the resultant closed-loop system is regular, impulse-free and stable. Numerical examples are proposed to illustrate the effectiveness of the proposed method. © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.

Zheng W.,Nanjing Southeast University | Lin Z.,Microsoft
Pattern Recognition | Year: 2012

FukunagaKoontz Transform (FKT) is a famous feature extraction method in statistical pattern recognition, which aims to find a set of vectors that have the best representative power for one class while the poorest representative power for the other class. Li and Savvides [1] propose a one-against-all strategy to deal with multi-class problems, in which the two-class FKT method can be directly applied to find the presentative vectors of each class. Motivated by the FKT method, in this paper we propose a new discriminant subspace analysis (DSA) method for the multi-class feature extraction problems. To solve DSA, we propose an iterative algorithm for the joint diagonalization (JD) problem. Finally, we generalize the linear DSA method to handle nonlinear feature extraction problems via the kernel trick. To demonstrate the effectiveness of the proposed method for pattern recognition problems, we conduct extensive experiments on real data sets and show that the proposed method outperforms most commonly used feature extraction methods. © 2011 Elsevier Ltd All rights reserved.

Qu X.,Nanjing Southeast University | Wong S.-C.,Hong Kong Polytechnic University | Tse C.K.,Hong Kong Polytechnic University
IEEE Transactions on Power Electronics | Year: 2011

LEDs are potential successors of incandescent lamps with high luminous efficacy and long lifetime. To improve the overall luminair efficacy and lifetime, the power efficiency and lifetime of LED ballasts become important factors. Efficiency gain in transformerless power converters appears attractive for applications without isolation. Driving solid-state LED bulbs in an existing lighting fixture such as PAR30 style housing from universal mains necessitates a high-voltage step-down ratio in order to produce an output voltage of about 10-20 V, which is very common in LED lighting applications. Traditional nonisolated step-down pulse width modulation buck converters may suffer from poor efficiency due to the long diode freewheeling time at small duty cycles. In this paper, we propose a resonance-assisted buck converter to achieve a high-voltage step-down ratio and high converter efficiency, whilst maintaining durability and compatibility with existing incandescent dimmers. The performance of the proposed LED driver is verified experimentally. © 2006 IEEE.

Xu W.X.,Nanjing Southeast University | Chen H.S.,Nanjing Southeast University
Modelling and Simulation in Materials Science and Engineering | Year: 2013

The determination of the volume fraction of interfacial layers is very significant for assessing the quantitative relationship between the microstructure and macroscopic physical properties of complex multiphase materials. In this work, based on a three-phase composite structure, an approximate analytical model for the volume fraction of interfacial layers around ellipsoidal aggregate particles is presented in detail. To verify the accuracy and reliability of the derived analytical model, a numerical model is introduced by means of random packing of polydispersed ellipsoidal aggregate particles, in which the relative spatial position between an arbitrary point and an ellipsoidal particle is precisely and conveniently determined. With the analytical and numerical models applied, the dependence of the volume fraction of interfacial layers on various factors, such as the particle shape, the volume fraction and the maximum particle size of aggregates, and the thickness of the interfacial layers, is evaluated. Furthermore, the results from the analytical model and the numerical model with these factors are compared. It is found that the theoretical results are favorably consistent with the simulated results. © 2013 IOP Publishing Ltd.

Wang H.,Nanjing Southeast University
IEEE Transactions on Biomedical Engineering | Year: 2011

The filtering technique for dimensionality reduction of multichannel electroencephalogram (EEG) recordings, modeled using common spatial patterns and its variants, is commonly used in two-class braincomputer interfaces (BCI). For a multiclass problem, the optimization of certain separability criteria in the output space is not directly related to the classification error of EEG single-trial segments. In this paper, we derive a new discriminant criterion, termed weighted pairwise criterion (WPC), for optimizing multiclass filters by minimizing the upper bound of the Bayesian error that is intentionally formulated for classifying EEG single-trial segments. The WPC approach pays more attention to close class pairs that are more likely to be misclassified than far away class pairs that are already well separated. Moreover, we extend WPC by integrating temporal information of EEG series. Computationally, we employ the rank-one update and power iteration technique to optimize the proposed discriminant criterion. The experiments of multiclass classification on the datasets of BCI competitions demonstrate the efficacy of the proposed method. © 2006 IEEE.

Lu J.,Nanjing Southeast University | Lu J.,City University of Hong Kong | Ho D.W.C.,City University of Hong Kong
Nonlinear Analysis: Real World Applications | Year: 2011

Under given performance constraint, this paper studies the stabilization problem of general dynamical network subject to noise disturbance. The newly presented dynamical network model includes both intrinsic disturbance of single node and communication noise over the network connections, which appear typically in a network environment. Single controller is pinned into one of the nodes for the exponential stabilization of dynamical network, and the prescribed performance constraint is satisfied. The reason why only one controller is valid for stabilization of dynamical network is the full utilization of network's local connections. One important feature of this paper is the introduction of the performance constraint concept into the stabilization of complex dynamical network with intrinsic and communication noises. The derived criteria are expressed in terms of linear matrix inequalities (LMIs), which are easy to be verified by resorting to recently developed algorithm. Numerical example is utilized to illustrate the effectiveness of the proposed results. © 2011 Elsevier Ltd. All rights reserved.

Usami T.,Meijo University | Wang C.-L.,Meijo University | Wang C.-L.,Nanjing Southeast University | Funayama J.,Meijo University
Earthquake Engineering and Structural Dynamics | Year: 2012

In order to enhance the durability of high-performance buckling-restrained braces (BRBs) used in bridge engineering, which are expected to withstand severe earthquakes three times without being replaced, aluminum alloys were employed to manufacture BRBs. A series of low-cycle fatigue tests, including 18 specimens, were conducted to address the low-cycle fatigue strength of the aluminum alloy BRB. Test results of all specimens show that stable hysteretic curves were obtained without overall buckling occurrence. Failure mode of the welded aluminum alloy BRB is obviously affected by the ribs' welding under the variable or constant strain amplitude condition. Therefore, another type of aluminum alloy BRB, the bolt-assembled BRB with or without spot-welded stoppers, is proposed and tested. Results showed that the low-cycle fatigue performance of bolt-assembled BRBs with stoppers improved four to five times compared with welded BRBs. However, the stoppers' spot welding has an adverse effect on the failure mode because the crack, which induced the specimen's failure, initiated from the spot weld toes of the stoppers. Both bolt-assembled BRBs with and without stoppers can meet the cumulative inelastic deformation requirement proposed for high-performance BRBs under the constant strain amplitude, not larger than 2%. In addition, under the variable strain amplitude condition, only the bolt-assembled BRB without stoppers has an excellent cumulative inelastic deformation capacity and sustains two cycles of 2.5% strain amplitude. Finally, recommended Manson-Coffin equations and preliminary cumulative damage formulae for welded and bolt-assembled BRBs are given as the references of the strain-based damage evaluation. © 2011 John Wiley & Sons, Ltd.

Yu W.,Nanjing Southeast University | Yu W.,University of Western Sydney | Zheng W.X.,University of Western Sydney | Chen G.,City University of Hong Kong | And 2 more authors.
Automatica | Year: 2011

This paper studies second-order consensus in multi-agent dynamical systems with sampled position data. A distributed linear consensus protocol with second-order dynamics is designed, where both the current and some sampled past position data are utilized. It is found that second-order consensus in such a multi-agent system cannot be reached without any sampled position data under the given protocol while it can be achieved by appropriately choosing the sampling period. A necessary and sufficient condition for reaching consensus of the system in this setting is established, based on which consensus regions are then characterized. It is shown that if all the eigenvalues of the Laplacian matrix are real, then second-order consensus in the multi-agent system can be reached for any sampling period except at some critical points depending on the spectrum of the Laplacian matrix. However, if there exists at least one eigenvalue of the Laplacian matrix with a nonzero imaginary part, second-order consensus cannot be reached for sufficiently small or sufficiently large sampling periods. In such cases, one nevertheless may be able to find some disconnected stable consensus regions determined by choosing appropriate sampling periods. Finally, simulation examples are given to verify and illustrate the theoretical analysis. © 2011 Elsevier Ltd. All rights reserved.

Chen Z.,Nanjing Southeast University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

The Dynamic Torque Analysis method (DTA) is applied to large scale power system via uniform linear modeling which can be integrated into system model with various kinds of controllers. Then the calculation process of DTA is proposed, and via some simplifications and assumptions on the channel of damping torque, the reconstruction of output and the extraction of sensitivity, the calculation method is simpler and clearer, which can be more easily extended to the calculation of large scale power system. Finally, the proposed DTA is extended to practical large-scale grid calculation and also applied to the analysis of HVDC and PSS controllers, and the effective results are obtained, which proves the feasibility and accuracy of the DTA algorithm applied extended to large scale power system.

Gao C.,Nanjing Southeast University | Wu X.,Nanjing Southeast University
Dianwang Jishu/Power System Technology | Year: 2013

Owing to its advantages, the battery-swapping mode is developed into an important energy supply mode of electric vehicles (EV), and at present the planning and the construction of battery-swapping networks are being carried out in major provinces and large cities in China, however the theoretical research in this field lags behind its application and dissemination and cannot meet the demand of the development in the field. Present developing situation of battery-swapping mode home and abroad is summarized, and the structure and features of two battery-swapping modes, namely the centralized charging mode and the charging and battery-swapping mode, are analyzed. The basic frame, operation mode and management system of battery-swapping network are presented. The planning and operation of battery-swapping network are analyzed in detail, and from the two aspects, i. e., the amount of batteries and the site selection and capability determination of charging station, the planning of battery-swapping network is researched; the battery dispatching strategy and battery charging management during practical operation phase of battery-swapping network are analyzed. Finally, the bottlenecks that the development of battery-swapping mode has to be faced with are enumerated, and research direction of this problem in future is prospected.

An Y.-K.,Nanjing Southeast University
International Journal of Solids and Structures | Year: 2015

This study aims to measure non-propagating Lamb wave modes (NPLs) for detection of a surface-breaking fatigue crack. Crack-induced NPLs are the attractive feature to identify and localize an invisible crack, because they are not spatially propagated but significantly contribute to local Lamb mode amplitudes at a crack interface. By extracting only the crack-induced NPLs from Lamb wavefields measured at multi-spatial points, the crack is able to be identified and localized without relying on baseline data obtained from the pristine condition of a target structure. First, the existence of the crack-induced NPLs are analytically proved using a modal expansion method. Then, a NPL filter based on a frequency-wavenumber analysis is proposed so that only NPLs are isolated from Lamb wavefields. Subsequently, the theoretical proof and the proposed NPL filter are numerically and experimentally validated through fatigue crack detection tests. In particular, the quantities of NPL generation at the real fatigue crack interface are investigated under changing driving frequencies as well as crack widths. The numerical and experimental results confirm that NPLs remarkably appear at open crack interfaces, while they are rarely induced at closed crack interfaces. © 2015 Elsevier Ltd.

Jin S.,Nanjing Southeast University | McKay M.R.,Hong Kong University of Science and Technology | Zhong C.,Queen's University of Belfast | Wong K.-K.,University College London
IEEE Transactions on Information Theory | Year: 2010

This paper presents an analytical characterization of the ergodic capacity of amplify-and-forward (AF) MIMO dual-hop relay channels, assuming that the channel state information is available at the destination terminal only. In contrast to prior results, our expressions apply for arbitrary numbers of antennas and arbitrary relay configurations. We derive an expression for the exact ergodic capacity, simplified closed-form expressions for the high SNR regime, and tight closed-form upper and lower bounds. These results are made possible by employing recent tools from finite-dimensional random matrix theory, which are used to derive new closed-form expressions for various statistical properties of the equivalent AF MIMO dual-hop relay channel, such as the distribution of an unordered eigenvalue and certain random determinant properties. Based on the analytical capacity expressions, we investigate the impact of the system and channel characteristics, such as the antenna configuration and the relay power gain. We also demonstrate a number of interesting relationships between the dual-hop AF MIMO relay channel and conventional point-to-point MIMO channels in various asymptotic regimes. © 2010 IEEE.

Zhu H.,Nanjing Southeast University | Sun L.,Nanjing Southeast University | Sun L.,Catholic University of America
International Journal of Plasticity | Year: 2013

Based on irreversible thermodynamics theory, a viscoelastic-viscoplastic damage constitutive model was derived from corresponding functions of free energy and dissipated potential. It characterizes the physical role of internal state variables while being consistent with the fundamental laws of thermodynamics. The developed constitutive model was applied to describe the triaxial creep and triaxial constant strain rate compression tests, and to predict time-dependent response of asphalt mixtures under various compression loading conditions. It shows that the model reasonably characterizes three-stage deformation of creep test, hardening and softening stages of constant strain rate compression test, creep and recovery during loading and unloading, as well as the accumulated permanent deformation after repeated loading-unloading. The predicted volumetric deformation exhibits contraction and dilation, in which viscoelastic component accounts for contraction, while viscoplastic damage component accounts for dilation. The model was also compared against several existing models when representing the permanent deformation behavior of asphalt mixtures to highlight its efficiency and capacity. © 2012 Elsevier Ltd. All rights reserved.

Sun L.,Catholic University of America | Sun L.,Nanjing Southeast University | Zhu Y.,Transportation Institute
Construction and Building Materials | Year: 2013

A serial two-stage viscoelastic-viscoplastic constitutive model is developed using internal variables theory and orthogonality principle of thermodynamics for modeling time-dependent behavior of asphalt concrete mixtures. In one stage when the actual stress is lower than the yield stress, the constitutive model only exhibit viscoelastic component, while in another stage when the actual stress exceeds the yield stress, the constitutive model exhibit both viscoelastic and viscoplastic components. Model parameters of viscoelastic component are estimated using data obtained from dynamic modulus test, whereas model parameters of viscoplastic component are consecutively estimated from creep test, assuming a known viscoelastic component. © 2012 Elsevier Ltd. All rights reserved.

Mi C.,Nanjing Southeast University | Kouris D.,Texas Christian University
International Journal of Solids and Structures | Year: 2013

Stress concentrations typically occur near discontinuities in structural elements and are often responsible for crack initiation. The aim of this study is to assess the stress concentration effects in the vicinity of a nanovoid located near a free surface. A semi-analytical investigation was carried out using the method of displacement potentials and coherent surface models. We investigated the dependence of stress concentration on a few important parameters like surface properties, external loads, bulk properties, as well as void size and location. Our analysis highlighted a few possible combinations of governing parameters that can reduce, prevent, and even reverse stress concentrations in nanoporous media. © 2013 Elsevier Ltd. All rights reserved.

Yu J.,Nanjing Southeast University | Zhang Y.,Nanjing Southeast University | Liu S.,Nanjing Southeast University
Biosensors and Bioelectronics | Year: 2014

The construction of nanodevices coupled with an integrated real-time detection system for evaluation of the function of biomolecules in biological processes, and enzymatic reaction kinetics occurring at the confined space or interface is a significant challenge. In this work, a nanochannel-enzyme system in which the enzymatic reaction could be investigated with an electrochemical method was constructed. The model system was established by covalently linking glucose oxidase (GOD) onto the inner wall of the nanochannels of the porous anodic alumina (PAA) membrane. An Au disc was attached at the end of the nanochannels of the PAA membrane as the working electrode for detection of H2O2 product of enzymatic reaction. The effects of ionic strength, amount of immobilized enzyme and pore diameter of the nanochannels on the enzymatic reaction kinetics were illustrated. The GOD confined in nanochannels showed high stability and reactivity. Upon addition of glucose to the nanochannel-enzyme system, the current response had a calibration range span from 0.005 to 2mM of glucose concentration. The apparent Michaelis-Menten constant (Kmapp) of GOD confined in nanochannel was 0.4mM. The presented work provided a platform for real-time monitoring of the enzyme reaction kinetics confined in nanospaces. Such a nanochannel-enzyme system could also help design future biosensors and enzyme reactors with high sensitivity and efficiency. © 2013 Elsevier B.V.

Wan X.,Nanjing Southeast University | Jiang W.X.,Nanjing Southeast University | Ma H.F.,Nanjing Southeast University | Cui T.J.,Nanjing Southeast University
Applied Physics Letters | Year: 2014

We present a transformational metasurface Luneburg lens based on the quasi-conformal mapping method, which has weakly anisotropic constitutive parameters. We design the metasurface lens using inhomogeneous artificial structures to realize the required surface refractive indexes. The transformational metasurface Luneburg lens is fabricated and the measurement results demonstrate very good performance in controlling the radiated surface waves. © 2014 AIP Publishing LLC.

Wang D.,Nanjing Southeast University
Toxicology Research | Year: 2016

Quantum dots (QDs), semiconductor nanomaterials with tiny light-emitting particles, act as important alternatives to conventional fluorescent dyes for biomedical imaging. With the increased tendency towards QD applications, concerns about the likelihood of adverse health impacts from exposure to QDs have also received attention. The nematode Caenorhabditis elegans is an important non-mammalian alternative model for the toxicological study of environmental toxicants including engineered nanomaterials. In this review, we summarize recent progress on the biological effects, translocation, and metabolism of QDs in the in vivo assay system of C. elegans. Moreover, certain perspectives or suggestions are further raised for the future toxicological study of QDs in nematodes. © The Royal Society of Chemistry 2016.

Luo Y.-H.,Nanjing Southeast University | Sun B.-W.,Nanjing Southeast University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2014

Three new co-crystals: pyridine-2-carboxamide-succinic acid (1), pyridine-2-carboxamide-glutaric acid (2) and pyridine-2-carboxamide-adipic acid (3) have been synthesized and characterized by single-crystal X-ray diffraction, TGA/DSC measurements, solid-state vibrational spectroscopy (IR and Raman) in this work. The investigation revealed that the carbon chain length of these alkyl acids changed the connecting motif of co-crystals 1-3 from trimer to 1D chain, and the formation of hydrogen bond interaction of pyridine-2-carboxamide with these alkyl acids lead to red shift of stretching vibration of NH 2 and OH groups in IR and Raman spectra. We also studied Hirshfeld surface and UV properties of co-crystals 1-3, and we found that the carbon chain length lead to decrease of close intermolecular interactions, and the formation of hydrogen bond interaction lead to red shift of UV spectra. © 2013 Elsevier B.V. All rights reserved.

Fang Z.,Nanjing Southeast University | Song H.-L.,Nanjing Southeast University | Cang N.,Nanjing Southeast University | Li X.-N.,Nanjing Southeast University
Bioresource Technology | Year: 2013

A microbial fuel cell coupled constructed wetland (planted with Ipomoea aquatica) system (planted CW-MFC) was used for azo dye decolorization. Electricity was simultaneously produced during the co-metabolism process of glucose and azo dye. A non-planted and an open-circuit system were established as reference to study the roles of plants and electrodes in azo dye decolorization and electricity production processes, respectively. The results indicated that plants grown in cathode enhanced the cathode potential and slightly promoted dye decolorization efficiency. The electrodes promoted the dye decolorization efficiency in the anode. The planted CW-MFC system achieved the highest decolorization rate of about 91.24% and a voltage output of about 610. mV. The connection of external circuit promoted the growth of electrogenic bacteria Geobacter sulfurreducens and Beta Proteobacteria, and inhibited the growth of Archaea in anode. © 2013 Elsevier Ltd.

Luo Y.-H.,Nanjing Southeast University | Sun B.-W.,Nanjing Southeast University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2014

Two new metastable crystalline forms of 6-chloroquinolin-2(1H)-one (forms II and III), which were induced by two kinds of 3D inorganic anions (ClO4- and BF4-), have been prepared and characterized in this work. We performed single-crystal diffraction, X-ray powder diffraction (XRPD), Hirshfeld surfaces, solid-state vibrational spectroscopy (IR) and thermal analysis (DSC, TGA) to these two new forms as well as the original one (form I). Form I featured with 1D chain, while form II and III featured with dimeric unit with stronger π⋯π and hydrogen bonds interactions. The 3D inorganic anions force the self-assemble behavior of 6-chloroquinolin-2(1H)-one molecules from 1D chain structure (form I) to dimeric unit (forms II and III) due to their large steric hindrance, and different anions induced different orientations for dimeric unit. These transformations lead to the increase of N-H⋯O, π⋯π, and Cl-Cl intermolecular interactions, which lead to blue shift of IR spectra in 1700-1500 cm-1 region as well as luminescence peaks, while red shift of IR spectra in 650-550 cm-1 region. © 2013 Elsevier B.V. All rights reserved.

Zhang H.,Nanjing Southeast University
Journal of Nanoscience and Nanotechnology | Year: 2012

Biocompatible nanomaterials have emerged as ideal platforms to develop multi-functionalization for achieving a compound effect using one system in which each component has a specially designed function. In this context, this article reviews multifunctional nanomedicine platforms for cancer therapy. The paper describes different types of multifunctional nanomedicine platforms, mainly co-delivery of drugs/genes in a single formulation for synergistic anticancer effect, specific strategies for targeting cancer therapy, smart control released drug delivery systems responding to certain internal or external stimuli, paradigms for theranostics to monitor effects in real time, and combination drug with thermal, sound, and light energies mediating multi-mode cancer treatment. Multifunctional nanomedicine platforms with different designs and therapeutic approaches for cancer and their translation from bench to bedside offer promising opportunities to benefit patients in the future. Copyright © 2012 American Scientific Publishers. All rights reserved.

Jiang S.,Nanjing Southeast University | Zheng S.,Nanjing Southeast University
Journal of Mechanical Design, Transactions of the ASME | Year: 2010

This technical brief presents a dynamic model based on the traditional transfer matrix method (TMM) and Jones-Harris nonlinear rolling bearing model to study the effects of the extended structure parameters on the vibration behavior of a high-speed motorized spindle-bearing system. The first critical speed and the dynamic stiffness of the high-speed motorized spindle-bearing system are systematically studied. A design sensitivity analysis of the structure parameters is then conducted to identify the main factor to affect the first critical speed of the spindle-bearing system. The results show that the processing condition, the shaft shoulder, the dimension of motor, and the bearing arrangement are sensitive to the spindle dynamic behavior. The TMM model of the spindlebearing system is verified by measuring the high-speed motorized spindle overall dynamic stiffness.

Li Z.Y.,Nanjing Southeast University
Circulation journal : official journal of the Japanese Circulation Society | Year: 2011

Inflammation and biomechanical factors have been associated with the development of vulnerable atherosclerotic plaques. Lipid-lowering therapy has been shown to be effective in stabilizing them by reducing plaque inflammation. Its effect on arterial wall strain, however, remains unknown. The aim of the present study was to investigate the role of high- and low-dose lipid-lowering therapy using an HMG-CoA reductase inhibitor, atorvastatin, on arterial wall strain. Forty patients with carotid stenosis >40% were successfully followed up during the Atorvastatin Therapy: Effects on Reduction Of Macrophage Activity (ATHEROMA; ISRCTN64894118) Trial. All patients had plaque inflammation as shown by intraplaque accumulation of ultrasmall super paramagnetic particles of iron oxide on magnetic resonance imaging at baseline. Structural analysis was performed and change of strain was compared between high- and low-dose statin at 0 and 12 weeks. There was no significant difference in strain between the 2 groups at baseline (P = 0.6). At 12 weeks, the maximum strain was significantly lower in the 80-mg group than in the 10-mg group (0.0850.033 vs. 0.1690.084; P = 0.001). A significant reduction (26%) of maximum strain was observed in the 80-mg group at 12 weeks (0.0180.02; P = 0.01). Aggressive lipid-lowering therapy is associated with a significant reduction in arterial wall strain. The reduction in biomechanical strain may be associated with reductions in plaque inflammatory burden.

Zhang Y.,Nanjing Southeast University | Tian Y.-P.,Nanjing Southeast University
IEEE Transactions on Automatic Control | Year: 2010

The consensus problem is considered for a team of second-order mobile agents communicating via a network with noise, variable delays and occasional packet losses. A queuing mechanism is applied and the switching process of the interaction topology of the network is modeled as a Bernoulli random process. In such a framework, a necessary and sufficient condition is presented for the mean-square robust consensus. Moreover, a necessary and sufficient condition of the solvability of the mean-square robust consensus problem is established. An approach to designing consensus protocol is proposed and numerical examples are given to illustrate the results. © 2006 IEEE.

Pan B.C.,Nanjing Southeast University | Liao Z.,Nanjing Southeast University | Zhao J.,Nanjing Southeast University | Cui T.J.,Nanjing Southeast University
Optics Express | Year: 2014

Based on the dispersion relation, surface plasmon polaritons (SPPs) or spoof SPPs are always propagating surface waves when the operating frequency is below the asymptotic limit - the surface plasma frequency. Here we propose a method to control the rejections of spoof SPPs using metamaterial particles. By introducing electrically resonant metamaterials near an ultrathin corrugated metallic strip - the spoof SPP waveguide - to produce tight coupling and mismatch of surface impedance, we show that the SPP modes are rejected near the resonant frequencies within the propagating band. Through the modulation of scaling factor of metamaterial particles, we can manipulate the rejections of SPP modes from narrowband to broadband. Both simulation and experiment results verify the tunability of SPP rejections, which have important applications in filtering SPP waves in plasmonic circuits and systems. © 2014 Optical Society of America.

Chen J.,Nanjing Southeast University | Wu G.,Nanjing Southeast University
Carbohydrate Polymers | Year: 2013

Based on studies of the forewings of two beetles, Allomyrina dichotoma and Prosopocoilus inclinatus, this paper reviews and identifies the potential benefits of studying the structure of the beetle forewing and the associated development of lightweight biomimetic composite materials. The forewings of both beetle species consist of an integrated border frame structure and a large center part with distributed trabecular supports in the hollow core. The forewings of the male A. dichotoma are constructed to reflect a lightweight honeycomb design. However, the forewings of P. inclinatus are a durable structure. The biological significance of these structures is also discussed. This work proposes an integrated honeycomb structure inspired by the beetle forewing. A series of biological models are also proposed for lightweight integrated honeycomb structures and durable sandwich structures with a trabecular core, which are intended to establish a new direction in the development of biomimetic composite materials. © 2012 Elsevier Ltd.

Chen Q.,Nanjing Southeast University | Pugno N.M.,University of Trento
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2013

Natural selection and evolution develop a huge amount of biological materials in different environments (e.g. lotus in water and opuntia in desert). These biological materials possess many inspiring properties, which hint scientists and engineers to find some useful clues to create new materials or update the existing ones. In this review, we highlight some well-studied (e.g. nacre shell) and newly-studied (e.g. turtle shell) natural materials, and summarize their hierarchical structures and mechanisms behind their mechanical properties, from animals to plants. These fascinating mechanisms suggest to researchers to investigate natural materials deeply and broadly, and to design or fabricate new bio-inspired materials to serve our life. © 2012 Elsevier Ltd.

Yun B.,Nanjing Southeast University | Hu G.,Nanjing Southeast University | Cui Y.,Nanjing Southeast University
Journal of Physics D: Applied Physics | Year: 2010

A compact and nanometric surface plasmon polariton (SPP) band-pass filter based on a rectangular ring resonator composed of metal-insulator-metal waveguides is proposed. Using the finite difference time domain method, the effects of the structure parameters on the transmission characteristics of this SPP band-pass filter are analysed in detail. The results show that the proposed SPP filter has narrow transmission peaks and the corresponding resonance wavelengths can be linearly tuned by altering the resonator's cavity length. Moreover, the transmission ratios of the pass bands can be tuned by changing the coupling gaps between the input/output MIM waveguides and the resonator. Also the metal loss and dispersion effects on the filter responses are included. The simple band-pass SPP filter is very promising for high-density SPP waveguide integrations. © 2010 IOP Publishing Ltd.

Xue P.,Nanjing Southeast University | Sanders B.C.,University of Calgary
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We consider two independent quantum walks on separate lines augmented by partial or full swapping of coins after each step. For classical random walks, swapping or not swapping coins makes little difference to the random-walk characteristics, but we show that quantum walks with partial swapping of coins have complicated yet elegant interwalker correlations. Specifically we study the joint position distribution of the reduced two-walker state after tracing out the coins and analyze total, classical, and quantum correlations in terms of mutual information, quantum mutual information, and measurement-induced disturbance. Our analysis shows intriguing quantum features without classical analogs. © 2012 American Physical Society.

Xue P.,Nanjing Southeast University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We study the spin-squeezing property of weighted graph states, which can be used to improve the sensitivity in interferometry. Decoherence reduces the spin-squeezing property but the result remains superior over other reference schemes with Greenberger-Horne-Zeilinger (GHZ) type maximally entangled states and product states. We study the time evolution of spin squeezing of weighted graph states coupled to different decoherence channels. Based on the analysis, the spin squeezing of the weighted graph states is robust in the presence of decoherence, and the decoherence limit in the improvement of the interferometric sensitivity is still achievable. © 2012 American Physical Society.

Chen S.,Nanjing Southeast University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We demonstrate that there exist globally convergent infinite tanh power series with which the spinless light-bullet solutions in the (3+1)D cubic-quintic complex Ginzburg-Landau equation can be exactly expressed. It is found that as these fixed-point bullet solutions exist, the series coefficients asymptotically approach certain nonzero constants; otherwise they oscillate and eventually decay to nil. In terms of the specific Padé approximants, the analytical solutions obtained for either the conventional bullets or the composite ones are in excellent agreement with numerical simulations. © 2012 American Physical Society.

Jiang W.-Z.,Nanjing Southeast University | Jiang W.-Z.,National Laboratory of Heavy Ion Accelerator
Physical Review C - Nuclear Physics | Year: 2010

Effects of the density dependence of the nuclear symmetry energy on ground-state properties of superheavy nuclei are studied in the relativistic mean-field theory. It is found that the softening of the symmetry energy plays an important role in the empirical shift of spherical orbitals in superheavy nuclei. The calculation based on the relativistic mean-field models NL3 and FSUGold supports the double shell closure in 292120 with the softening of the symmetry energy. In addition, the significant effect of the density dependence of the symmetry energy on the neutron skin thickness in superheavy nuclei is investigated. © 2010 The American Physical Society.

Binfeng Y.,Nanjing Southeast University | Guohua H.,Nanjing Southeast University | Ruohu Z.,Nanjing Southeast University | Yiping C.,Nanjing Southeast University
Optics Express | Year: 2014

A nanometric and high sensitive refractive index sensor based on the metal-insulator-metal plasmonic Bragg grating is proposed. The wavelength encoded sensing characteristics of the refractive index sensor were investigated by analyzing its transmission spectrum. The numerical results show that a good linear relationship between the Bragg wavelength and the refractive index of the sensing material can be obtained, which is in accordance with the analytical results very well. A high refractive index sensitivity of 1488nm/RIU around Bragg resonance wavelength of 1550nm was obtained. Besides, the simulation results show that the sensitivity is depended on the Bragg resonance wavelength and the longer the Bragg resonance wavelength, the higher sensitivity can be obtained. Furthermore, the figure of merit of the refractive index sensor can be greatly increased by introducing a nano-cavity in the proposed plasmonic Bragg grating structure. This work pave the way for high sensitive nanometric refractive index sensor design and application. ©2014 Optical Society of America

Ye W.,Nanjing Southeast University
Physical Review C - Nuclear Physics | Year: 2010

Using a one-dimensional Langevin model, we study the effects of deformation on the multiplicities of postsaddle neutrons, protons, α particles, and giant dipole resonance (GDR) γ rays of a heavy fissioning system Cf240 as probes of postsaddle nuclear dissipation (β). It is shown that postsaddle dissipation effects on these light particles have a significant deformation dependence. Furthermore, we find that the role of deformation depends on the type of the particle. It reduces the sensitive influence of β on protons, α particles, and GDR γ rays substantially, whereas it enhances the sensitivity of neutrons to β. The results suggest that to accurately extract the postsaddle friction strength by comparing measured prescission particle multiplicities of heavy nuclei with calculations based on statistical models or stochastic equations like Langevin equations, it is important to take into account the deformation effects. The influence of model dimensionality is discussed. © 2010 The American Physical Society.

Lu W.,Nanjing Southeast University | Zhou K.,University of Canterbury | Wang D.,Nanyang Technological University | Cheng M.,Nanjing Southeast University
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, a generic digital nk ± m-order harmonic repetitive control (nk ± m RC) scheme is presented for constant-voltage constant-frequency pulsewidth-modulation (PWM) converters to track/remove any nk ± m-order harmonic frequencies efficiently, e.g., 4k ± 1-order harmonics for single-phase converters or 6k ± 1-order harmonics for three-phase converters. Compared with conventional RC, the proposed nk ± m RC occupies less data memory and can achieve zero-error tracking or perfect disturbance rejection of nk ± m-order harmonics at much faster error convergence rate. What is more, the proposed RC provides a unified formula for various RC schemes. Application examples of 6k ± 1-RC-controlled three-phase PWM inverter and 4k ± 1 -RC-controlled single-phase PWM inverter demonstrate the effectiveness and advantages of the proposed RC scheme. © 1982-2012 IEEE.

Xie Y.,Nanjing Southeast University | Fu D.,Nanjing Southeast University
Materials Chemistry and Physics | Year: 2010

Titanium planar sheet formed by a chemical polishing process and titania nanotube array formed by an electrochemical anodization process are used as electrode substrates, on which electroactive ruthenium oxides are deposited by an electroreduction and electrooxidation process for supercapacitor applications. Morphological characterization and electrochemical properties of the electrode substrates and ruthenium oxide electrodes have been investigated. Crystalline titania nanotube array shows a much higher electric double layer capacitance than titanium planar sheet due to its high surface area of nanotube walls. Additionally, the well-defined ruthenium oxide-titania/titanium nanotube array electrode exhibits a much higher redox supercapacitance and a lower capacitance decay than ruthenium oxide/titanium planar film electrode. Such a superior energy-storage performance of ruthenium oxide-titania/titanium is ascribed to highly accessible nanotube channels for the reversible redox reaction of ruthenium oxide. The modification strategy of ruthenium oxide electrode by introducing highly ordered nanotube array structure instead of planar film structure can significantly improve specific capacitance as well as cyclic charge-discharge stability. © 2010 Elsevier B.V. All rights reserved.

Zeng H.,Nanjing Southeast University
Sensors (Basel, Switzerland) | Year: 2013

Ocular contamination of EEG data is an important and very common problem in the diagnosis of neurobiological events. An effective approach is proposed in this paper to remove ocular artifacts from the raw EEG recording. First, it conducts the blind source separation on the raw EEG recording by the stationary subspace analysis, which can concentrate artifacts in fewer components than the representative blind source separation methods. Next, to recover the neural information that has leaked into the artifactual components, the adaptive signal decomposition technique EMD is applied to denoise the components. Finally, the artifact-only components are projected back to be subtracted from EEG signals to get the clean EEG data. The experimental results on both the artificially contaminated EEG data and publicly available real EEG data have demonstrated the effectiveness of the proposed method, in particular for the cases where limited number of electrodes are used for the recording, as well as when the artifact contaminated signal is highly non-stationary and the underlying sources cannot be assumed to be independent or uncorrelated.

Chen S.,Nanjing Southeast University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

In terms of a tanh-series representation, the stationary dissipative solitons such as arbitrary-amplitude solitons, plain solitons, flattop solitons, and composite solitons in complex Ginzburg-Landau (CGL) systems can be exactly described, as confirmed by extensive simulations. It thus suggests another route to understanding solitons in CGL-like systems that is highly accurate. © 2012 American Physical Society.

Li M.,Nanjing Southeast University | Wu Z.,Nanjing Southeast University | Kao H.,Nanjing University of Technology
Solar Energy Materials and Solar Cells | Year: 2011

The choice of fatty acids as shape-stabilized phase change materials (PCMs) will increase the feasibilities of PCMs in practical applications due to the low price of the fatty acids. Compounding different fatty acids for each other is an effective way to obtain a PCM with a suitable phase-transition temperature. In this study, a series of binary fatty acids composed by capric acid, lauric acid, palmitic acid and stearic acid for each other were prepared using the phase diagram thermal dynamics calculation method. Then these binary fatty acids are absorbed in four kinds of diatomites with different specific areas, which act as a supporting material, to prepare shape-stabilized PCMs. The prepared shape-stabilized PCMs are characterized by the Scanning electron microscope (SEM) and the differential scanning calorimetry (DSC) analysis method. The results show that there is an optimum absorption ratio between binary fatty acids and the diatomite. The latent heat of capriclauric acid/diatomite decreases to 57% of that of capriclauric acid, and the phase-transition temperature rises from 16.36 to 16.74 °C when the capriclauric acid is absorbed in the diatomite. The prepared capriclauric acid/diatomite composite PCM has proper melting temperatures and latent heat for thermal energy storage application in buildings. © 2011 Elsevier B.V.

Manipulation of tumor microRNAs (miRNAs) may offer novel avenues for treatment of cancer. However, development of safe, robust, non-viral delivery methods remains a main challenge to obtain the promise of gene therapy. The miR-145 is dysregulated in many cancers, including colon carcer, and further in vitro investigation established antiproliferative and proapoptotic roles of miR-145. Herein, we study a PLGA/PEI (poly (d, l-lactide-co-glycolide)/polyethylenimine)-mediated miRNA vector delivery system; the validation of the method was carried out using a colon cancer xenograft model with miR-145 vector encoding for the expression of miR-145 (pDNA). First, high-molecular-weight PEI (25000 Da) was conjugated with cetyl to formulate reducible cetylated PEI (PEI-cet), and then PEI-cet was introduced to PLGA suspension. Next, PLGA/PEI-cet was crosslinked with hyaluronic acid (HA) to facilitate cellular uptake of miRNA plasmid vector via HA receptor-mediated endocytosis. After local administration of PLGA/PEI/HA complexes, intact miRNA plasmid vectors were delivered into HCT-116 colon cancer cells and xenograft tumor-bearing mice, and significant antitumor effects were achieved. The results show that the HA-based miR-145 nanocarrier could efficiently facilitate cellular uptake and significantly enhance miR-145 expression in HCT-116 cells. Consequently, the increased miR-145 induced G1 cell cycle arrest, reduced tumor proliferation and increased apoptosis, inhibited HCT-116 cell migration and suppressed c-MYC expressions, a regulatory target of miR-145. Of particular importance is the significant decrease in tumor growth in the mice model of colon cancer with the targeting miR-145 delivery system. The results in this work show that miR-145 has been effectively delivered to colon carcinomas through a PLGA/PEI/HA vehicle, indicating a promising miRNA replacement therapy strategy.Gene Therapy advance online publication, 1 September 2016; doi:10.1038/gt.2016.60. © 2016 Macmillan Publishers Limited, part of Springer Nature.

Xu F.,Nanjing Southeast University | Sun L.,Nanjing Southeast University
Energy and Environmental Science | Year: 2011

Solution-phase derived ZnO nanostructures have triggered considerable interest and become the mainstream route to obtain low-cost and large-scale electrode materials for dye-sensitized solar cells (DSSCs). The article reviews recent progress in liquid-phase synthesis methods for preparing ZnO nanostructures as the photoanodes of the DSSCs. A few classic paradigms and new advancements in the ZnO nanostructures made by our group are demonstrated. The effects of ZnO nanostructured films with different morphologies, prepared by solution-phase approaches, on the performance of DSSCs are discussed. Finally, various liquid-phase methods of ZnO nanostructure synthesis are summarized and compared to allow further exploration of the ways to improve the photoelectric conversion efficiency of DSSCs. © 2011 The Royal Society of Chemistry.

Liang J.,Nanjing Southeast University | Wang Z.,Brunel University | Liu X.,Brunel University
International Journal of Robust and Nonlinear Control | Year: 2012

In this paper, the distributed state estimation problem is investigated for a class of sensor networks described by uncertain discrete-time dynamical systems with Markovian jumping parameters and distributed time-delays. The sensor network consists of sensor nodes characterized by a directed graph with a nonnegative adjacency matrix that specifies the interconnection topology (or the distribution in the space) of the network. Both the parameters of the target plant and the sensor measurements are subject to the switches from one mode to another at different times according to a Markov chain. The parameter uncertainties are norm-bounded that enter into both the plant system as well as the network outputs. Furthermore, the distributed time-delays are considered, which are also dependent on the Markovian jumping mode. Through the measurements from a small fraction of the sensors, this paper aims to design state estimators that allow the nodes of the sensor network to track the states of the plant in a distributed way. It is verified that such state estimators do exist if a set of matrix inequalities is solvable. A numerical example is provided to demonstrate the effectiveness of the designed distributed state estimators. © 2011 John Wiley & Sons, Ltd.

Behrman J.R.,University of Pennsylvania | Xiong Y.,Nanjing Southeast University | Zhang J.,Chinese University of Hong Kong
Social Science and Medicine | Year: 2015

Adult health outcomes and health behaviors are often associated with schooling. However, such associations do not necessarily imply that schooling has causal effects on health with the signs or magnitudes found in the cross-sectional associations. Schooling may be proxying for unobserved factors related to genetics and family background that directly affect both health and schooling. Recently several studies have used within-monozygotic (MZ) twins methods to control for unobserved factors shared by identical twins. Within-MZ estimates for developed countries are generally smaller than suggested by cross-sectional associations, consistent with positive correlations between unobserved factors that determine schooling and those that determine health. This study contributes new estimates of cross-sectional associations and within-MZ causal effects using the Chinese Adults Twins Survey, the first study of its type for developing countries. The cross-sectional estimates suggest that schooling is significantly associated with adult health-related behaviors (smoking, drinking, exercising) but not with own or spouse health outcomes (general health, mental health, overweight, chronic diseases). However, within-MZ-twins estimators change the estimates for approximately half of these health indicators, in one case declining in absolute magnitudes and becoming insignificant and in the other cases increasing in absolute magnitudes. Within-MZ estimates indicate significant pro-health effects for at least one of the indicators for own health (better mental health), own health-related behaviors (less smoking) and spouse health (less overweight). © 2014 Elsevier Ltd.

Ye W.,Nanjing Southeast University
Physical Review C - Nuclear Physics | Year: 2010

Using a Langevin model, we explore the role of fissility in probing presaddle nuclear dissipation by calculating the excess of the evaporation residue cross section over its standard statistical-model value as a function of nuclear dissipation strength for nuclei Os190 and Po210, which are taken as two representatives that have the same neutron-to-proton ratio (N/Z) but have a difference in fissility. We find that a large fissility not only amplifies the dissipation effects on the excess of evaporation residues, but also significantly increases the sensitivity of this excess to nuclear dissipation. The results suggest that in experiments, to obtain a more accurate information of nuclear dissipation inside the saddle point by measuring evaporation residue cross sections, it is best to populate among the various compound systems with equal N/Z those with high fissility. © 2010 The American Physical Society.

Hu H.,Nanjing Southeast University
Sensors (Basel, Switzerland) | Year: 2014

Sliding tactile perception is a basic function for human beings to determine the mechanical properties of object surfaces and recognize materials. Imitating this process, this paper proposes a novel finger-shaped tactile sensor based on a thin piezoelectric polyvinylidene fluoride (PVDF) film for surface texture measurement. A parallelogram mechanism is designed to ensure that the sensor applies a constant contact force perpendicular to the object surface, and a 2-dimensional movable mechanical structure is utilized to generate the relative motion at a certain speed between the sensor and the object surface. By controlling the 2-dimensional motion of the finger-shaped sensor along the object surface, small height/depth variation of surface texture changes the output charge of PVDF film then surface texture can be measured. In this paper, the finger-shaped tactile sensor is used to evaluate and classify five different kinds of linen. Fast Fourier Transformation (FFT) is utilized to get original attribute data of surface in the frequency domain, and principal component analysis (PCA) is used to compress the attribute data and extract feature information. Finally, low dimensional features are classified by Support Vector Machine (SVM). The experimental results show that this finger-shaped tactile sensor is effective and high accurate for discriminating the five textures.

Hu S.,Nanjing Southeast University
Asia-Pacific Microwave Conference Proceedings, APMC | Year: 2016

Millimeter-wave (mmWave) and terahertz (THz) technologies have been showing their great potentials for Gbps high-speed communication and biomedical imaging. This paper briefly reviews part of our research advances in these topics, especially in antenna and integrated circuit (IC) chips. Following that, this paper also preliminarily discusses the component related challenging issues and possible approaches for Gbps communication as well as biomedical imaging. © 2015 IEEE.

Xu O.,Nanjing Southeast University
Journal of Electromagnetic Waves and Applications | Year: 2011

The genetic algorithm (GA) is applied to the optimization of a sub-millimeter wave horn-lens collimation equipment operating at 150 GHz, and measurement is carried out to validate the performance of the optimized geometry. The aperture-integration (AI) method is employed to formulate the fitness function of GA in dealing with complex field distribution from an arbitrary radiation source. A diagonal horn and the auxiliary lens are fabricated according to the GA-optimized geometry, and their radiation properties are measured employing a BWO (Backward-wave Oscillator) with a golay cell terahertz detector. The measurement indicates that the gain and near-field beam radius conform to the values predicted by GA. © 2011 VSP.

Wang W.,Guangxi Normal University | Liu X.,Nanjing Southeast University
Computers and Mathematics with Applications | Year: 2013

This article proposes an approach to multi-attribute decision making (MADM) where individual assessments are provided as interval-valued intuitionistic fuzzy numbers (IVIFNs). Firstly, some Einstein geometric operators on interval-valued intuitionistic fuzzy sets, such as Einstein product, Einstein exponentiation etc., and their characteristics are introduced. Secondly, some Einstein geometric operators, such as the interval-valued intuitionistic fuzzy Einstein weighted geometric operator, interval-valued intuitionistic fuzzy Einstein ordered weighted geometric operator and interval-valued intuitionistic fuzzy Einstein hybrid weighted geometric (IV IFHWGε) operator, are developed for aggregating the IVIFNs. Moreover, various properties of these operators are established. Finally, an IV IFHWGε operator based approach to MADM under interval-valued intuitionistic fuzzy environments is proposed. An illustrative propulsion/manoeuvring system selection problem is employed to demonstrate how to apply the proposed procedure and verify the feasibility and effectiveness of the developed method. © 2013 Elsevier Ltd. All rights reserved.

Zhu Q.,Ningbo University | Cao J.,Nanjing Southeast University
Neurocomputing | Year: 2011

In this paper, we study a new class of stochastic Cohen-Grossberg neural networks with reaction-diffusion and mixed delays. Without the aid of nonnegative semimartingale convergence theorem, the method of variation parameter and linear matrix inequalities technique, a set of novel sufficient conditions on the exponential stability for the considered system is obtained by utilizing a new Lyapunov-Krasovskii functional, the Poincaré inequality and stochastic analysis theory. The obtained results show that the reaction-diffusion term does contribute to the exponentially stabilization of the considered system. Therefore, our results generalize and improve some earlier publications. Moreover, two numerical examples are given to show the effectiveness of the theoretical results and demonstrate that the stability criteria existed in the earlier literature fail. © 2011 Elsevier B.V.

Zhang Y.-N.,Nanjing Southeast University | Sun Z.-Z.,Nanjing Southeast University
Journal of Computational Physics | Year: 2011

New numerical techniques are presented for the solution of a two-dimensional anomalous sub-diffusion equation with time fractional derivative. In these methods, standard central difference approximation is used for the spatial discretization, and, for the time stepping, two new alternating direction implicit (ADI) schemes based on the L1 approximation and backward Euler method are considered. The two ADI schemes are constructed by adding two different small terms, which are different from standard ADI methods. The solvability, unconditional stability and H1 norm convergence are proved. Numerical results are presented to support our theoretical analysis and indicate the efficiency of both methods. © 2011 Elsevier Inc.

Zhao W.,Nanjing Southeast University
American Journal of Tropical Medicine and Hygiene | Year: 2010

Secondary or reactive hemophagocytic syndrome (HPS) is frequently related to viral infections. However, the novel swine-origin influenza A (H1N1) virus associated HPS has never been reported. On October 10, 2009, a 17-year-old female child with no past medical history, complaining of severe asthenia, pneumonia, myalgia, and high fever, was admitted to our department, and H1N1 DNA was detected. Five days after her hospitalization, all signs and symptoms aggravated into HPS. After treatment for H1N1 influenza, the patient had a recovery and clearance of H1N1 infection 10 days after hospitalization. Three weeks later, the patient was discharged without any complaints, indicating the etiological role of H1N1infection in HPS. Copyright © 2010 by The American Society of Tropical Medicine and Hygiene.

Jianguo C.,Nanjing Southeast University
Journal of Mechanisms and Robotics | Year: 2016

Rolling joints, which are created by attaching two cylindrical surfaces of equal radius using two or more thin tapes or cable, are used for rigid origami considering the panel thickness. First, the concept and two implementation methods of this joint are given. Then planar linkages are chosen to study the mobility and kinematics of foldable plate structures with rolling joints. It can be found that the rolling joints preserve the full-cycle-motion of foldable plate structures. From the closure equations of linkages, the results show that the outputs of linkages with rolling joints are the same as that with traditional revolute joints if the lengths of links are equal. However, the results are different when the lengths of links are unequal. Moreover, the difference between linkages with rolling joints and revolute joints increases with an increase of the size of rolling joints. © 2016 by ASME.

Jiang H.,Nanjing Southeast University | Tang R.-N.,Nanjing Southeast University | Wang J.,Nanjing Medical University
European Journal of Clinical Microbiology and Infectious Diseases | Year: 2013

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of nosocomial pneumonia. Compared with glycopeptide antibiotics, linezolid achieves higher lung epithelial lining fluid concentrations, which may have an advantage in treating nosocomial pneumonia patients. The objective of this study was to evaluate the efficacy and safety of linezolid versus vancomycin or teicoplanin for the treatment of nosocomial pneumonia. Data were obtained from the Cochrane Central Register of Controlled Trials and the EMBASE and MEDLINE databases. Randomised controlled studies involving the use of linezolid versus vancomycin or teicoplanin in nosocomial pneumonia patients were included in the study. Twelve linezolid trials were included. There was no statistically significant difference between the two groups in the treatment of nosocomial pneumonia regarding the clinical cure rate [relative risk (RR) = 1.08, 95 % confidence interval (CI) = 1.00-1.17, p = 0.06]. Linezolid was associated with better microbiological eradication rate in nosocomial pneumonia patients compared with glycopeptide antibiotics (RR = 1.16, 95 % CI = 1.03-1.31, p = 0.01). There were no differences in the all-cause mortality (RR = 0.95, 95 % CI = 0.83-1.09, p = 0.46) between the two groups. However, the risks of rash (RR = 0.41, 95 % CI = 0.24-0.71, p = 0.001) and renal dysfunction (RR = 0.41, 95 % CI = 0.27-0.64, p < 0.0001) were higher with glycopeptide antibiotics. Although linezolid was more effective in eradicating microbiology than glycopeptide antibiotics for nosocomial pneumonia patients, it did not demonstrate superiority in clinical cure. The incidences of renal dysfunction and rash are higher in the glycopeptide antibiotics group. © 2013 Springer-Verlag Berlin Heidelberg.

Xu Z.,Nanjing Southeast University | Xu Z.,Chinese University of Hong Kong | Cai X.,Chinese University of Hong Kong
Information Sciences | Year: 2011

In many group decision-making situations, decision makers' preferences for alternatives are expressed in preference relations (including fuzzy preference relations and multiplicative preference relations). An important step in the process of aggregating preference relations, is to determine the importance weight of each preference relation. In this paper, we develop a number of goal programming models and quadratic programming models based on the idea of maximizing group consensus. Our models can be used to derive the importance weights of fuzzy preference relations and multiplicative preference relations. We further develop iterative algorithms for reaching acceptable levels of consensus in group decision making based on fuzzy preference relations or multiplicative preference relations. Finally, we include an illustrative example. © 2010 Published by Elsevier Inc.

In view of the dissatisfactory capability of the -insensitive loss function in field of white (Gaussian) noise of multi-dimensional load series, a new wavelet v-support vector machine with Gaussian loss function which is called Wg-SVM is put forward to penalize the Gaussian noises. To seek the optimal parameters of Wg-SVM, modified genetic algorithm (GA) is proposed to optimize parameters of Wg-SVM. The results of application in load forecasts show that the forecasting approach based on the Wg-SVM model is effective and feasible, the comparison between the method proposed in this paper and other ones is also given, which proves this method is better than other SVM methods. © 2010 Elsevier Ltd. All rights reserved.

Liu X.,Nanjing Southeast University | Yu S.,Deakin University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2012

The ordered weighted averaging (OWA) determination method with stress function was proposed by Yager, and it makes the OWA operator elements scatter in the shape of the stress function. In this paper, we extend the OWA determination with the stress function method using an optimization model. The proposed method transforms the OWA optimal solution elements into the interpolation points of the stress function. The proposed method extends the basic form of the stress function method with both scale and vertical shift transformations. We also explore a number of properties of this optimization-based stress function method. The OWA operator optimal solution elements can distribute as the shape of the given stress function in a parameterized way, in which case, the solution always possesses the arithmetic average operator as a special case. © 2011 IEEE.

Geng X.,Nanjing Southeast University
IEEE Transactions on Knowledge and Data Engineering | Year: 2016

Although multi-label learning can deal with many problems with label ambiguity, it does not fit some real applications well where the overall distribution of the importance of the labels matters. This paper proposes a novel learning paradigm named label distribution learning (LDL) for such kind of applications. The label distribution covers a certain number of labels, representing the degree to which each label describes the instance. LDL is a more general learning framework which includes both single-label and multi-label learning as its special cases. This paper proposes six working LDL algorithms in three ways: problem transformation, algorithm adaptation, and specialized algorithm design. In order to compare the performance of the LDL algorithms, six representative and diverse evaluation measures are selected via a clustering analysis, and the first batch of label distribution datasets are collected and made publicly available. Experimental results on one artificial and 15 real-world datasets show clear advantages of the specialized algorithms, which indicates the importance of special design for the characteristics of the LDL problem. © 1989-2012 IEEE.

Gu W.,Nanjing Southeast University | Zhou T.,University of Texas at Austin | Wilke C.O.,University of Texas at Austin
PLoS Computational Biology | Year: 2010

Recent studies have suggested that the thermodynamic stability of mRNA secondary structure near the start codon can regulate translation efficiency in Escherichia coli, and that translation is more efficient the less stable the secondary structure. We survey the complete genomes of 340 species for signals of reduced mRNA secondary structure near the start codon. Our analysis includes bacteria, archaea, fungi, plants, insects, fishes, birds, and mammals. We find that nearly all species show evidence for reduced mRNA stability near the start codon. The reduction in stability generally increases with increasing genomic GC content. In prokaryotes, the reduction also increases with decreasing optimal growth temperature. Within genomes, there is variation in the stability among genes, and this variation correlates with gene GC content, codon bias, and gene expression level. For birds and mammals, however, we do not find a genome-wide trend of reduced mRNA stability near the start codon. Yet the most GC rich genes in these organisms do show such a signal. We conclude that reduced stability of the mRNA secondary structure near the start codon is a universal feature of all cellular life. We suggest that the origin of this reduction is selection for efficient recognition of the start codon by initiator-tRNA. © 2010 Gu et al.

Yao X.,Nanjing Southeast University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2015

The Kitaev-Heisenberg model on the honeycomb lattice is investigated in two cases: (I) with the Kitaev interaction between the nearest neighbors, and (II) with the Kitaev interaction between the next nearest neighbors. In the full parameter range, the ground states are searched by Monte Carlo simulation and identified by evaluating the correlation functions. The energies of different phases are calculated and compared with the simulated result to show the phase competition. It is observed from both energy calculation and the density of states that the zigzag order shows a symmetric behavior to the stripy phase in the pure Kitaev-Heisenberg model. By considering more interactions in both cases, the energy of zigzag order can be reduced lower than the energies of other states. Thus the zigzag phase may be stabilized in more parameter region and even extended to the whole parameter range. © 2015 Elsevier B.V.All rights reserved.

Zhang J.,Nanjing Southeast University | Wen C.-K.,National Sun Yat - sen University | Jin S.,Nanjing Southeast University | Gao X.,Nanjing Southeast University | Wong K.-K.,University College London
IEEE Journal on Selected Areas in Communications | Year: 2013

In this paper, a deterministic equivalent of ergodic sum rate and an algorithm for evaluating the capacity-achieving input covariance matrices for the uplink large-scale multiple-input multiple-output (MIMO) antenna channels are proposed. We consider a large-scale MIMO system consisting of multiple users and one base station with several distributed antenna sets. Each link between a user and an antenna set forms a two-sided spatially correlated MIMO channel with line-of-sight (LOS) components. Our derivations are based on novel techniques from large dimensional random matrix theory (RMT) under the assumption that the numbers of antennas at the terminals approach to infinity with a fixed ratio. The deterministic equivalent results (the deterministic equivalent of ergodic sum rate and the capacity-achieving input covariance matrices) are easy to compute and shown to be accurate for realistic system dimensions. In addition, they are shown to be invariant to several types of fading distribution. © 2012 IEEE.