Chengdu, China
Chengdu, China

The University of Electronic Science and Technology of China is a research-intensive university in Chengdu, China. Wikipedia.

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University of Electronic Science and Technology of China | Date: 2016-12-07

The present invention relates to a serpentine film heater for adjusting temperature uniformity and a method of temperature adjusting, including a substrate and a serpentine film heating wire which is deposited on the substrate, wherein the serpentine film heating wire is formed by several parallel heating sections and connecting lines. In the longitudinal direction, the temperature uniformity is improved by adjusting the spacings between adjacent heating sections or line widths of the heating sections separately or in combination. In the transverse direction, the every heating section is adjusted to a shape which is wide in center and narrow at two ends. By adjusting the spacings and line widths in both transverse and longitudinal directions the present invention reduces heating power in the central part of the substrate and increases the heating power on the edges, thus compensates the heat transfer difference between center and edges and improves the temperature uniformity.

Patent
University of Electronic Science, Technology of China and Institute Of Electronic And Information Engineering In Dongguan | Date: 2016-12-07

A bidirectional Metal-Oxide-Semiconductor (MOS) device, including a P-type substrate, and an active region. The active region includes a drift region, a first MOS structure and a second MOS structure; the first MOS structure includes a first P-type body region, a first P+ contact region, a first N+ source region, a first metal electrode, and a first gate structure; the second MOS structure includes a second P-type body region, a second P+ contact region, a second N+ source region, a second metal electrode, and a second gate structure; and the drift region includes a dielectric slot, a first N-type layer, a second N-type layer, and an N-type region. The active region is disposed on the upper surface of the P-type substrate. The first MOS structure and the second MOS structure are symmetrically disposed on two ends of the upper layer of the drift region.

Liu C.,National University of Singapore | Liu C.,University of Electronic Science and Technology of China | Guo Y.-X.,National University of Singapore | Xiao S.,University of Electronic Science and Technology of China
IEEE Transactions on Antennas and Propagation | Year: 2014

A single-fed miniaturized circularly polarized microstrip patch antenna is designed and experimentally demonstrated for industrial-scientific-medical (2.4-2.48 GHz) biomedical applications. The proposed antenna is designed by utilizing the capacitive loading on the radiator. Compared with the initial topology of the proposed antenna, the so-called square patch antenna with a center-square slot, the proposed method has the advantage of good size reduction and good polarization purity. The footprint of the proposed antenna is 10 × 10 × 1.2mm3. The simulated impedance, axial ratio, and radiation pattern are studied and compared in two simulation models: cubic skin phantom and Gustav voxel human body. The effect of different body phantoms is discussed to evaluate the sensitivity of the proposed antenna. The effect of coaxial cable is also discussed. Two typical approaches to address the biocompatibility issue for practical applications are reported as well. The simulated and measured impedance bandwidths in cubic skin phantom are 7.7% and 10.2%, respectively. The performance of the communication link between the implanted CP antenna and the external antenna is also presented. © 2014 IEEE.

Wang M.,South China University of Technology | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China | Hong K.-S.,Pusan National University
IEEE Transactions on Neural Networks | Year: 2010

This paper presents adaptive neural tracking control for a class of non-affine pure-feedback systems with multiple unknown state time-varying delays. To overcome the design difficulty from non-affine structure of pure-feedback system, mean value theorem is exploited to deduce affine appearance of state variables xi as virtual controls αi and of the actual control The separation technique is introduced to decompose unknown functions of all time-varying delayed states into a series of continuous functions of each delayed state. The novel LyapunovKrasovskii functionals are employed to compensate for the unknown functions of current delayed state, which is effectively free from any restriction on unknown time-delay functions and overcomes the circular construction of controller caused by the neural approximation of a function of and mathdotu. Novel continuous functions are introduced to overcome the design difficulty deduced from the use of one adaptive parameter. To achieve uniformly ultimate boundedness of all the signals in the closed-loop system and tracking performance, control gains are effectively modified as a dynamic form with a class of even function, which makes stability analysis be carried out at the present of multiple time-varying delays. Simulation studies are provided to demonstrate the effectiveness of the proposed scheme. © 2006 IEEE.

Ni D.,University of Electronic Science and Technology of China | Ni D.,University of Windsor | Li K.W.,University of Windsor | Li K.W.,Tokyo Institute of Technology
International Journal of Production Economics | Year: 2012

This research investigates how two supply chain members, a downstream firm (F) and an upstream supplier (S), interact with each other with respect to corporate social responsibility (CSR) behavior and what impact exogenous parameters may have on this interaction. A game-theoretic analysis is conducted to obtain equilibriums for both simultaneous-move and sequential-move CSR games. Under certain assumptions, it is concluded that (1) there exists a mutual incentive between their CSR behavior, whereby a win-win performance in terms of both CSR and profitability is achieved as long as exogenous parameters exceed certain critical thresholds; (2) a higher consumer marginal social-benefit potential (MSBP) or a lower consumer marginal perception difficulty (MPD) helps to lower the critical thresholds of CSR budgets and CSR operational efficiency by S and F, making it easier to achieve the win-win performance; (3) an increase in one supply chain members CSR budget or CSR operational efficiency tends to make the supply chain easier to attain a win-win performance scenario; (4) if CSR decisions are made sequentially, a prior commitment to CSR activities from one supply chain member strengthens the mutual incentive and facilitates the realization of the win-win performance. Business implications of these research findings are also discussed. © 2012 Elsevier B.V. All rights reserved.

Dong B.,Zhejiang University | Ni D.,University of Electronic Science and Technology of China | Wang Y.,University of Windsor
Environmental and Resource Economics | Year: 2012

A polluted river network is populated with agents (e. g., firms, villages, municipalities, or countries) located upstream and downstream. This river network must be cleaned, the costs of which must be shared among the agents. We model this problem as a cost sharing problem on a tree network. Based on the two theories in international disputes, namely the Absolute Territorial Sovereignty (ATS) and the Unlimited Territorial Integrity (UTI), we propose three different cost sharing methods for the problem. They are the Local Responsibility Sharing (LRS), the Upstream Equal Sharing (UES), and the Downstream Equal Sharing (DES), respectively. The LRS and the UES generalize Ni and Wang (Games Econ Behav 60:176-186, 2007) but the DES is new. The DES is based on a new interpretation of the UTI. We provide axiomatic characterizations for the three methods. We also show that they coincide with the Shapley values of the three different games that can be defined for the problem. Moreover, we show that they are in the cores of the three games, respectively. Our methods can shed light on pollution abatement of a river network with multiple sovereignties. © 2012 Springer Science+Business Media B.V.

Zou Y.,Nanjing University of Posts and Telecommunications | Li X.,CAS Xi'an Institute of Optics and Precision Mechanic | Liang Y.-C.,Institute for Infocomm Research | Liang Y.-C.,University of Electronic Science and Technology of China
IEEE Journal on Selected Areas in Communications | Year: 2014

In this paper, we investigate the physical-layer security of a multi-user multi-eavesdropper cognitive radio system, which is composed of multiple cognitive users (CUs) transmitting to a common cognitive base station (CBS), {while multiple eavesdroppers may collaborate with each other or perform independently in intercepting the CUs-CBS transmissions, which are called the coordinated and uncoordinated eavesdroppers, respectively. Considering multiple CUs available, we propose the round-robin scheduling as well as the optimal and suboptimal user scheduling schemes for improving the security of CUs-CBS transmissions against eavesdropping attacks. Specifically, the optimal user scheduling is designed by assuming that the channel state information (CSI) of all links from CUs to CBS, to primary user (PU) and to eavesdroppers are available. By contrast, the suboptimal user scheduling only requires the CSI of CUs-CBS links without the PU's and eavesdroppers' CSI. We derive closed-form expressions of the secrecy outage probability of these three scheduling schemes in the presence of {the coordinated and uncoordinated eavesdroppers. We also carry out the secrecy diversity analysis and show that the round-robin scheduling achieves the diversity order of only one, whereas the optimal and suboptimal scheduling schemes obtain the full secrecy diversity, {no matter whether the eavesdroppers collaborate or not. In addition, numerical secrecy outage results demonstrate that for both the coordinated and uncoordinated eavesdroppers, the optimal user scheduling achieves the best security performance and the round-robin scheduling performs the worst. Finally, upon increasing the number of CUs, the secrecy outage probabilities of the optimal and suboptimal user scheduling schemes both improve significantly. © 2014 IEEE.

Li Y.,National University of Singapore | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
IEEE/ASME Transactions on Mechatronics | Year: 2014

In this paper, adaptive impedance control is proposed for a robot collaborating with a human partner, in the presence of unknown motion intention of the human partner and unknown robot dynamics. Human motion intention is defined as the desired trajectory in the limb model of the human partner, which is extremely difficult to obtain considering the nonlinear and time-varying property of the limb model. Neural networks are employed to cope with this problem, based on which an online estimation method is developed. The estimated motion intention is integrated into the developed adaptive impedance control, which makes the robot follow a given target impedance model. Under the proposed method, the robot is able to actively collaborate with its human partner, which is verified through experiment studies. © 1996-2012 IEEE.

He W.,University of Electronic Science and Technology of China | Zhang S.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, a flexible cable with a payload attached at the bottom is considered to be the model of a crane system used for positioning the payload. The dynamics of the flexible cable coupled with the tip payload contribute to a hybrid system represented by partial-ordinary differential equations. An integral-barrier Lyapunov function (IBLF)-based control is proposed to suppress the undesirable vibrations of the flexible crane system with the boundary output constraint. Adaption laws are developed for handling parametric uncertainties. A novel IBLF is adopted to guarantee the uniform stability of the closed-loop systems without the violation of the boundary constraint. All closed-loop signals are ensured to be bounded. Extensive simulations are demonstrated to illustrate the performance of the control system. © 2013 IEEE.

Vu T.L.,National University of Singapore | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China | Hang C.C.,National University of Singapore
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We exploit the notion of SWM- (simultaneous-weak-measurements)-induced quantum state reduction, enabling the use of measurement backaction to produce the desired quantum states. The probabilistic generation of maximally entangled Bell states and the |GHZ (Greenberger-Horne-Zeilinger) state are then performed as a consequence of this notion. By combining SWM-induced quantum state reduction with feedback control, we are able to deterministically generate any desired Bell state as well as the |GHZ state, without the knowledge of the initial state. The control-computation time is compensated for by the delay time in the time-delay bang-bang control, through which the real-time implementation of the control scheme is guaranteed. The effectiveness of the proposed scheme is illustrated numerically. © 2012 American Physical Society.

Yang H.-X.,Fuzhou University | Rong Z.,University of Electronic Science and Technology of China | Wang W.-X.,Beijing Normal University
New Journal of Physics | Year: 2014

The paradox of cooperation among selfish individuals still puzzles scientific communities. Although a large amount of evidence has demonstrated that the cooperator clusters in spatial games are effective in protecting the cooperators against the invasion of defectors, we continue to lack the condition for the formation of a giant cooperator cluster that ensures the prevalence of cooperation in a system. Here, we study the dynamical organization of the cooperator clusters in spatial prisoner's dilemma game to offer the condition for the dominance of cooperation, finding that a phase transition characterized by the emergence of a large spanning cooperator cluster occurs when the initial fraction of the cooperators exceeds a certain threshold. Interestingly, the phase transition belongs to different universality classes of percolation determined by the temptation to defect b. Specifically, on square lattices, 1 < b < 4/3 leads to a phase transition pertaining to the class of regular site percolation, whereas 3/2 < b < 2 gives rise to a phase transition subject to invasion percolation with trapping. Our findings offer a deeper understanding of cooperative behavior in nature and society. © 2014 IOP Publishing and Deutsche Physikalische Gesellschaft.

Guo J.,CAS Institute of Theoretical Physics | Li J.,University of Adelaide | Li T.,CAS Institute of Theoretical Physics | Li T.,University of Electronic Science and Technology of China | Williams A.G.,University of Adelaide
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

The Galactic center excess is explained in the framework of the Next-to-Minimal Supersymmetric Standard Model with a Z3 discrete symmetry. We show that a resonant CP-odd Higgs boson with mass twice that of the Dark Matter (DM) candidate is favored. Meanwhile, the DM candidate is required to have relatively large coupling with the Z boson through its Higgsino component in order to obtain correct DM relic density. Its LHC discovery potential via four signatures is discussed in detail. We find that the most sensitive signals are provided by the Higgsino-like chargino and neutralino pair production with their subsequent decays into W bosons, Z bosons, and DM. The majority of the relevant parameter space can be probed at the Large Hadron Collider with a center-of-mass energy of 14 TeV and an integrated luminosity 1000 fb-1. © 2015 American Physical Society.

Lin P.,University of Electronic Science and Technology of China | Ren W.,University of California at Riverside
Proceedings of the IEEE Conference on Decision and Control | Year: 2012

In this paper, we study a distributed subgradient projection algorithm for multi-agent optimization with nonidentical constraints and switching topologies. We first show that distributed optimization might not be achieved on general strongly connected graphs. Instead, the agents optimize a weighted average of the local objective functions. Then we prove that distributed optimization can be achieved when the adjacency matrices are doubly stochastic and the union of the graphs is strongly connected among each time interval of a certain bounded length. © 2012 IEEE.

Zhang Y.,University of Electronic Science and Technology of China | Li L.,University of Swansea
Nano Energy | Year: 2016

Experimental findings on electroluminescence or photoluminescence of ZnO nanowires have been drawn much attention due to their promising applications in many areas. One of the current challenges on this technology is a deeper understanding of this phenomenon in order to adopt it into practical device designs. In this work, a theoretical analysis of the stimulated emission of ZnO nanowires taking into consideration of the piezotronics effect has been conducted using the quantum mechanics theory. It is revealed that extra piezoelectric charges induced by applied mechanical forces increase the overall charge density of the nanowire, subsequently enhancing the emission intensity. Electronic bandgap varying with the diameter of the nanowire determines the peak value in the electromagnetic spectrum. Both wavelength and intensity of the stimulated emission can be tuned by controlling the dimension of the nanowires and external applied mechanical forces. © 2016 Elsevier Ltd.

He W.,National University of Singapore | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
IEEE Transactions on Control Systems Technology | Year: 2012

In this paper, robust adaptive boundary control is developed for a class of flexible string-type systems under unknown time-varying disturbance. The dynamics of the string system is represented by a nonhomogeneous hyperbolic partial differential equation (PDE) and two ordinary differential equations. Boundary control is proposed at the right boundary of the string based on the original distributed parameter system model (PDE) to suppress the vibration excited by the external unknown disturbance. Adaptive control is designed to compensate the system parametric uncertainty. With the proposed robust adaptive boundary control, all the signals in the closed-loop system are guaranteed to be uniformly ultimately bounded. The state of the string system is proven to converge to a small neighborhood of zero by appropriately choosing design parameters. Simulations are provided to illustrate the effectiveness of the proposed control. © 2006 IEEE.

Wei H.-W.,China Institute of Technology | Peng R.,Cisco Systems | Wan Q.,University of Electronic Science and Technology of China | Chen Z.-X.,University of Electronic Science and Technology of China | Ye S.-F.,China Institute of Technology
IEEE Transactions on Signal Processing | Year: 2010

A new framework for positioning a moving target is introduced by utilizing time differences of arrival (TDOA) and frequency differences of arrival (FDOA) measurements collected using an array of passive sensors. It exploits the multidimensional scaling (MDS) analysis, which has been developed for data analysis in the field such as physics, geography and biology. Particularly, we present an accurate and closed-form solution for the position and velocity of a moving target. Unlike most passive target localization methods focusing on minimizing a loss function with respect to the measurement vector, the proposed method is based on the optimization of a cost function related to the scalar product matrix in the classical MDS framework. It is robust to the large measurement noise. The bias and variance of the proposed estimator is also derived. Simulation results show that the proposed estimator achieves better performance than the spherical-interpolation (SI) method and the two-step weighted least squares (WLS) approach, and it attains the Cramér-Rao lower bound at a sufficiently high noise level before the threshold effect occurs. Moreover, for the proposed estimator the threshold effect, which is a result of the nonlinear nature of the localization problem, occurs apparently later as the measurement noise increases for a near-field target. © 2010 IEEE.

He W.,National University of Singapore | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China | Zhang S.,National University of Singapore
Automatica | Year: 2011

In this paper, boundary control of a marine installation system is developed to position the subsea payload to the desired set-point and suppress the cable's vibration. Using Hamilton's principle, the flexible cable coupled with vessel and payload dynamics is described as a distributed parameter system with one partial differential equation (PDE) and two ordinary differential equations (ODEs). Adaptive boundary control is proposed at the top and bottom boundaries of the cable, based on Lyapunov's direct method. Considering the system parametric uncertainty, the boundary control schemes developed achieve uniform boundedness of the steady state error between the boundary payload and the desired position. The control performance of the closed-loop system is guaranteed by suitably choosing the design parameters. Simulations are provided to illustrate the applicability and effectiveness of the proposed control. © 2011 Elsevier Ltd. All rights reserved.

Liu X.,Southwest University for Nationalities | Liu X.,University of Electronic Science and Technology of China | Yu W.,East China Normal University | Wang L.,Peking University
IEEE Transactions on Automatic Control | Year: 2010

This note addresses the stability problem of continuous-time positive systems with time-varying delays. It is shown that such a system is asymptotically stable for any continuous and bounded delay if and only if the sum of all the system matrices is a Hurwitz matrix. The result is a time-varying version of the widely-known asymptotic stability criterion for constant-delay positive systems. A numerical example illustrates the correctness of our result. © 2006 IEEE.

Chen B.,Qingdao University | Liu X.P.,Lakehead University | Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore | Lin C.,Qingdao University
IEEE Transactions on Fuzzy Systems | Year: 2012

Controlling nonstrict-feedback nonlinear systems is a challenging problem in control theory. In this paper, we consider adaptive fuzzy control for a class of nonlinear systems with nonstrict-feedback structure by using fuzzy logic systems. A variable separation approach is developed to overcome the difficulty from the nonstrict-feedback structure. Furthermore, based on fuzzy approximation and backstepping techniques, a state feedback adaptive fuzzy tracking controller is proposed, which guarantees that all of the signals in the closed-loop system are bounded, while the tracking error converges to a small neighborhood of the origin. Simulation studies are included to demonstrate the effectiveness of our results. © 2012 IEEE.

Cheng Y.J.,National University of Singapore | Cheng Y.J.,University of Electronic Science and Technology of China | Bao X.Y.,National University of Singapore | Guo Y.X.,National University of Singapore
IEEE Transactions on Antennas and Propagation | Year: 2013

In this paper, miniaturized substrate integrated multibeam array antennas are proposed and designed at 60 GHz. Owing to the design flexibility of the low temperature cofired ceramic (LTCC) technology, the entire multibeam antenna size is only equal to the size of radiating aperture by carefully embedding the complicated substrate integrated waveguide (SIW) feeding network underneath the radiating array. After introducing design procedures for the folded Butler matrix and the corresponding radiating array, a ±45° dual linear-polarization (LP) and a dual circular-polarization (CP) substrate integrated multibeam array antennas are designed and fabricated, respectively. Here, each multibeam antenna has four switchable beams with different pointing directions. Each beam direction has two orthogonal LP or CP modes, therefore allowing the polarization diversity.Measured results validate our design and demonstrate good performances of our proposed structures. © 2013 IEEE.

He W.,University of Electronic Science and Technology of China | Zhang S.,University of Electronic Science and Technology of China | Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore
Automatica | Year: 2014

In this paper, robust adaptive control is developed for a thruster assisted position mooring system in the transverse direction. To provide an accurate and concise representation for the dynamic behavior of the mooring system, the flexible mooring lines are modeled as a distributed parameter system of partial differential equations (PDEs). The proposed control is applied at the top boundary of the mooring lines for station keeping via Lyapunov's direct method. Adaptive control is designed to handle the system parametric uncertainties. With the proposed robust adaptive control, uniform boundedness of the system under the ocean current disturbance is achieved. The proposed control is implementable with actual instrumentations since all the signals in the control can be measured by sensors or calculated by using a backward difference algorithm. The effectiveness of the proposed control is verified by numerical simulations. © 2014 Elsevier Ltd. All rights reserved.

He W.,University of Electronic Science and Technology of China | Zhang S.,University of Electronic Science and Technology of China | Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore
IEEE Transactions on Control Systems Technology | Year: 2014

In this brief, the vibration control problem is investigated for a flexible string system in both transverse and longitudinal directions. The vibrating string is nonlinear due to the coupling between transverse and longitudinal displacements. Using the Hamilton's principle, the dynamics of the nonlinear string are presented by two partial and four ordinary differential equations. With the Lyapunov's direct method, adaptive boundary control is developed to suppress the string's vibration and the adaptive law is designed to compensate for the system parametric uncertainties. With the proposed control, the states of the system eventually converge to a compact set. Numerical simulations are carried out to verify the effectiveness of the proposed control. © 2014 IEEE.

He W.,University of Electronic Science and Technology of China | Sun C.,University of Toronto | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
IEEE/ASME Transactions on Mechatronics | Year: 2014

This paper presents a boundary controller for a flexible marine riser to suppress the riser's vibration with a top tension constraint. The flexible marine riser is described by a distributed parameter system with a partial differential equation and four ordinary differential equations. The boundary controller is designed at the top boundary of the riser based on an integral-barrier Lyapunov function to suppress the riser's tension at top. Adaptive control is designed when the system parametric uncertainty exists. With the proposed robust adaptive boundary control, uniformed boundedness under the ocean disturbance can be achieved. Stability analysis of the closed-loop system is given using the Lyapunov stability theory. Simulation results illustrate the effectiveness of the proposed boundary controller with top tension constraint. © 2014 IEEE.

He W.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
IEEE/ASME Transactions on Mechatronics | Year: 2015

In this paper, the vibration control problem is studied for a wind turbine tower subjected to random wind loads. The tower is modeled as a nonuniform Euler-Bernoulli beam system with distributed parameters by using the Hamilton's principle. The control force is applied at the top boundary of the tower to suppress the vibrations of the tower. Disturbance observer is designed to attenuate the disturbance at the top of the tower. The stability of the whole system is rigorously proved via the Lyapunov analysis and the satisfactory control performance is guaranteed under the proper choice of the design parameters. Numerical results are provided to illustrate that the designed controller is effective in dissipating the vibrations of the tower. © 1996-2012 IEEE.

Qu S.-W.,University of Electronic Science and Technology of China | Chen Q.-Y.,Beijing Institute of Technology | Xia M.-Y.,Peking University | Zhang X.Y.,South China University of Technology
IEEE Transactions on Antennas and Propagation | Year: 2014

This paper presents two kinds of novel elements to design single-layer dual-band reflectarray, with identical polarization in two closely separated bands. Several degrees of freedom of the proposed elements are tuned to match the desired phase compensations at two center frequencies simultaneously. It is noted that the dual-band characteristics are realized by a single integrated element rather than conventional dual-band elements with independent tunable components corresponding to two center frequencies. A 10× 10-element offset-fed reflectarray operating at 9 and 13.5 GHz, with a ratio of the center frequencies 1.5, is designed and fabricated to validate the performance of the element, and the measured results show reasonable agreements with simulations. Due to the incompleteness of reflection phase distribution at the two center frequencies of the presented element, a complementary element with four resonances is introduced. Then, a 20× 20-element reflectarray composed of both kinds of elements is also designed, and the measured results demonstrate a good availability of the proposed elements. © 2013 IEEE.

Jun S.,University of Electronic Science and Technology of China | Xiaoling Z.,University of Electronic Science and Technology of China | Jianyu Y.,University of Electronic Science and Technology of China | Chen W.,China Institute of Technology
IEEE Transactions on Geoscience and Remote Sensing | Year: 2010

This paper discusses the antenna phase center trajectory (APCT) design for the "one-active" linear-array 3-D imaging SAR (LASAR). First, we discuss the principle of the one-active LASAR and demonstrate its feasibility by experiment. To describe the 3-D spatial resolution of the one-active LASAR, the relationship between the 3-D ambiguity function (AF) of the one-active LASAR and the system parameters is discussed in detail. Based on the analysis, we divide the APCT design into three topics: the direction of the linear array, the length of the linear array, and the switching mode of the active element [named as antenna phase center function (APCF)]. On the first topic, we conclude that, when the range, along-track, and cross-track directions are orthogonal to each other, the ambiguity region of the one-active LASAR attains minimum, and the 3-D spatial resolution can be separated into the range, along-track, and cross-track resolutions. On the second topic, we find that the cross-track resolution is determined by the length of the linear array and the frequency of the carrier. To ensure that the length of the linear array is acceptable, the carrier should beW-band wave or millimeter wave. On the third topic, the effect of APCF is researched, and we find that both the periodic APCF and the pseudorandom APCF can produce 3-D resolution, except for the periodic rectangle APCF. For the pseudorandom APCF and the periodic APCF with short period, the cross-range 2-D AF is or can be approximated as the product of two 1-D AFs in the along-and cross-track directions. Finally, the distribution of the pseudorandom APCF is optimized by the Lagrange multiplier method under the minimum variance criterion, and we find that, when the pseudorandom APCF obeys the parabolic distribution, the cross-range 2-D AF is optimal. © 2009 IEEE.

Tang Z.,Sichuan Agricultural University | Yang Z.,University of Electronic Science and Technology of China | Fu S.,Sichuan Agricultural University
Journal of Applied Genetics | Year: 2014

Hybrids derived from wheat (Triticum aestivum L.) × rye (Secale cereale L.) have been widely studied because of their important roles in wheat cultivar improvement. Repetitive sequences pAs1, pSc119.2, pTa-535, pTa71, CCS1, and pAWRC.1 are usually used as probes in fluorescence in situ hybridization (FISH) analysis of wheat, rye, and hybrids derived from wheat × rye. Usually, some of these repetitive sequences for FISH analysis were needed to be amplified from a bacterial plasmid, extracted from bacterial cells, and labeled by nick translation. Therefore, the conventional procedure of probe preparation using these repetitive sequences is time-consuming and labor-intensive. In this study, some appropriate oligonucleotide probes have been developed which can replace the roles of repetitive sequences pAs1, pSc119.2, pTa-535, pTa71, CCS1, and pAWRC.1 in FISH analysis of wheat, rye, and hybrids derived from wheat × rye. These oligonucleotides can be synthesized easily and cheaply. Therefore, FISH analysis of wheat and hybrids derived from wheat × rye using these oligonucleotide probes becomes easier and more economical. © 2014 Institute of Plant Genetics, Polish Academy of Sciences, Poznan.

Han T.,National University of Singapore | Han T.,University of Electronic Science and Technology of China | Qiu C.-W.,National University of Singapore
Optics Express | Year: 2010

We propose a novel kind of trapeziform cloak requiring only homogeneous anisotropic materials. Large-scale flat cloaks can be degenerated from the general trapeziform cloak with PEC inner boundary, and be realized by isotropic nonmagnetic materials for optical frequencies with controlled index profiles and improved invisibility. With the support of PEC inner boundary, large vehicles and objects of arbitrary shape can be concealed between the PEC and ground, and PEC can be firm by adding pillars in the cloaking space. Full-wave simulations validate the proposed cloaking concept, which is not only based on simple isotropic nonmagnetic materials but also realizable in practice. © 2010 Optical Society of America.

Chen M.,Nanjing University of Aeronautics and Astronautics | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
IEEE Transactions on Industrial Electronics | Year: 2015

In this paper, an adaptive neural output feedback control scheme is proposed for uncertain nonlinear systems that are subject to unknown hysteresis, external disturbances, and unmeasured states. To deal with the unknown nonlinear function term in the uncertain nonlinear system, the approximation capability of the radial basis function neural network (RBFNN) is employed. Using the approximation output of the RBFNN, the state observer and the nonlinear disturbance observer (NDO) are developed to estimate unmeasured states and unknown compounded disturbances, respectively. Based on the RBFNN, the developed NDO, and the state observer, the adaptive neural output feedback control is proposed for uncertain nonlinear systems using the backstepping technique. The first-order sliding-mode differentiator is employed to avoid the tedious analytic computation and the problem of "explosion of complexity" in the conventional backstepping method. The stability of the whole closed-loop system is rigorously proved via the Lyapunov analysis method, and the satisfactory tracking performance is guaranteed under the integrated effect of unknown hysteresis, unmeasured states, and unknown external disturbances. Simulation results of an example are presented to illustrate the effectiveness of the proposed adaptive neural output feedback control scheme for uncertain nonlinear systems. © 1982-2012 IEEE.

Han T.,University of Electronic Science and Technology of China | Han T.,National University of Singapore | Qiu C.-W.,National University of Singapore | Tang X.,University of Electronic Science and Technology of China
Optics Letters | Year: 2011

We propose a method for adaptive waveguide bends using homogeneous, nonmagnetic, and isotropic materials, which simplifies the parameters of the bends to the utmost extent. The proposed bend has an adaptive and compact shape because of all the flat boundaries. The nonmagnetic property is realized by selecting OB′=OC / 0:5. Only two nonmagnetic isotropic dielectrics are needed throughout, and the transmission is not sensitive to nonmagnetic isotropic dielectrics. Results validate and illustrate these functionalities, which make the bend much easier to fabricate and apply, owing to its simple parameters, compact shape, and versatility in connecting different waveguides. © 2011 Optical Society of America.

He W.,University of Electronic Science and Technology of China | Zhang S.,National University of Singapore | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
IEEE Transactions on Industrial Electronics | Year: 2013

This paper considers a modeling and control problem for a Timoshenko beam under spatiotemporally varying disturbance. The model of the Timoshenko beam is represented by a hybrid model including both partial differential equations and ordinary differential equations. In order to suppress the vibration of the system, boundary control is proposed based on Lyapunov's direct method. Boundary disturbance observers are designed to reduce the effects of the external disturbances. With the proposed boundary control strategies, the states of the system are proven to be uniformly ultimately bounded and converge to a small neighborhood of zero by choosing the design parameters. Simulations are displayed to show the effectiveness of the proposed boundary control. © 1982-2012 IEEE.

Li Z.,South China University of Technology | Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore
IET Control Theory and Applications | Year: 2013

This paper presents a structure of robust adaptive control for biped robots, which includes balancing and posture control for regulating the centre-of-mass (COM) position and trunk orientation of bipedal robots in a compliant way. First, the biped robot is decoupled into the dynamics of COM and the trunks. Then, the adaptive robust controls are constructed in the presence of parametric and functional dynamics uncertainties. The control computes a desired ground reaction force required to stabilise the posture with unknown dynamics of COM and then transforms these forces into fullbody joint torques even if the external disturbances exist. Based on Lyapunov synthesis, the proposed adaptive controls guarantee that the tracking errors of system converge to zero. The proposed controls are robust not only to system uncertainties such as mass variation but also to external disturbances. The verification of the proposed control is conducted using the extensive simulations. © The Institution of Engineering and Technology 2013.

He W.,University of Electronic Science and Technology of China | Zhang S.,National University of Singapore | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
IEEE Transactions on Industrial Electronics | Year: 2013

This paper investigates the control problem of a marine riser installation system. The riser installation system consisting of a vessel, a flexible riser, and a subsea payload is modeled as a distributed parameter system with one partial differential equation and four ordinary differential equations. Based on Lyapunov's direct method, adaptive boundary control is proposed at the top and bottom boundaries of the riser to position the subsea payload to the desired set point and suppress the riser's vibration. With the proposed control, uniform boundedness of the steady-state error between the boundary payload and the desired position is achieved by suitably choosing the design parameters. Numerical simulations are presented for demonstrating the effectiveness of the proposed control. © 1982-2012 IEEE.

Li L.-W.,University of Electronic Science and Technology of China | Li L.-W.,National University of Singapore | Li Y.-N.,National University of Singapore | Yeo T.S.,National University of Singapore | And 2 more authors.
Applied Physics Letters | Year: 2010

A broad bandwidth and high gain rectangular patch antenna was specifically designed in this paper using planar-patterned metamaterial concepts. Based on an ordinary patch antenna, the antenna has isolated triangle gaps and crossed strip-line gaps etched on the metal patch and ground plane, respectively. Demonstrated to have left-handed characteristics, the patterned metal patch and finite ground plane form a coupled capacitive-inductive circuit of negative index metamaterial. It is shown to have great impact on the antenna performance enhancement in terms of the bandwidth significantly broadened from a few hundred megahertz to a few gigahertz, and also in terms of high efficiency, low loss, and low voltage standing wave ratio. Experimental data show a reasonably good agreement between the simulation and measured results. This antenna has strong radiation in the horizontal direction for some specific applications within the entire band. © 2010 American Institute of Physics.

Yu J.,University of Electronic Science and Technology of China | Yu J.,Peking University | Wang L.,Peking University | Yu M.,North China Electrical Power University
International Journal of Robust and Nonlinear Control | Year: 2011

Stabilization problems of networked control systems (NCSs) with bounded packet losses and transmission delays are addressed. We model such NCSs as a class of switched systems, and establish stabilizing conditions in the form of matrix inequalities by using packet-loss dependent Lyapunov functions. By solving the inequalities, packet-loss dependent controllers are designed for two types of packet-loss processes: one is an arbitrary packet-loss process, and the other is a Markovian packet-loss process. Several numerical examples and simulations are worked out to demonstrate the effectiveness of the proposed design techniques. © 2010 John Wiley & Sons, Ltd.

Li F.,University of Electronic Science and Technology of China | Li F.,Fujian Normal University | Khan M.K.,King Saud University
Future Generation Computer Systems | Year: 2012

Signcryption is a high performance cryptographic primitive that fulfills both the functions of digital signature and public key encryption simultaneously, at a cost significantly lower than that required by the traditional signature-then-encryption approach. In this paper, we introduce biometrics into identity-based signcryption. We formalize the notion of biometric identity-based signcryption and propose an efficient biometric identity-based signcryption scheme that uses biometric information to construct the public key. We prove that our scheme satisfies confidentiality and unforgeability in the random oracle model. We show that both the computational costs and the communication overheads of our scheme are lower than those of the signature-then-encryption approach. © 2010 Elsevier B.V. All rights reserved.

Lin P.,University of Electronic Science and Technology of China | Ren W.,University of California at Riverside
Proceedings of the IEEE Conference on Decision and Control | Year: 2012

In this paper, a constrained consensus problem is studied in unbalanced networks in the presence of communication delays. Here each agent needs to lie in a closed convex set while reaching a consensus. The communication graphs considered are directed, dynamically changing, and not necessarily balanced and only the union of the graphs is assumed to be strongly connected among each time interval of a certain bounded length. The analysis is performed based on an undelayed equivalent system that is composed of a linear main body and an error auxiliary. It is showed that the error auxiliary vanishes as time evolves and the linear main body converges to a vector with an exponential rate as a separate system. It is also showed that the communication delays do not affect the consensus stability and consensus is achieved even though the communication delays are arbitrary bounded. © 2012 IEEE.

Mi W.,University of Electronic Science and Technology of China | Qian T.,University of Macau
Automatica | Year: 2014

In this paper, we present an algorithm for estimating poles of linear time-invariant systems by using the backward shift operator. We prove that poles of rational functions, including zeros and multiplicities, are solutions to an algebraic equation which can be obtained by taking backward shift operator to the shifted Cauchy kernels in the unit disc case. The algorithm is accordingly developed for frequency-domain identification. We also prove the robustness of this algorithm. Some illustrative examples are presented to show the efficiency in systems with distinguished and multiple poles. © 2014 Elsevier Ltd. All rights reserved.

Liu X.-X.,University of California at Riverside | Wang H.,University of Electronic Science and Technology of China | Tan S.X.-D.,University of California at Riverside
IEEE/ACM International Conference on Computer-Aided Design, Digest of Technical Papers, ICCAD | Year: 2013

In this paper, we propose an efficient parallel dynamic linear solver, called GPU-GMRES, for transient analysis of large power grid networks. The new method is based on the preconditioned generalized minimum residual (GMRES) iterative method implemented on heterogeneous CPU-GPU platforms. The new solver is very robust and can be applied to power grids with different structures and other applications like thermal analysis. The proposed GPU-GMRES solver adopts the very general and robust incomplete LU (ILU) based preconditioner. We show that by properly selecting the right amount of fill-ins in the incomplete LU factors, a good trade-off between GPU efficiency and GMRES convergence rate can be achieved for the best overall performance. Such a tunable feature makes this algorithm very adaptive to different problems. Furthermore, we properly partition the major computing tasks in GMRES solver to minimize the data traffic between CPU and GPU, which further boosts performance of the proposed method. Experimental results on the set of published IBM benchmark circuits and mesh-structured power grid networks show that the GPU-GMRES solver can deliver order of magnitudes speedup over the direct LU solver UMFPACK. GPU-GMRES can also deliver 3-10× speedup over the CPU implementation of the same GMRES method on transient analysis. © 2013 IEEE.

Chen M.,Nanjing University of Aeronautics and Astronautics | Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore
IEEE Transactions on Cybernetics | Year: 2013

In this paper, the direct adaptive neural control is proposed for a class of uncertain nonaffine nonlinear systems with unknown nonsymmetric input saturation. Based on the implicit function theorem and mean value theorem, both state feedback and output feedback direct adaptive controls are developed using neural networks (NNs) and a disturbance observer. A compounded disturbance is defined to take into account of the effect of the unknown external disturbance, the unknown nonsymmetric input saturation, and the approximation error of NN. Then, a disturbance observer is developed to estimate the unknown compounded disturbance, and it is established that the estimate error converges to a compact set if appropriate observer design parameters are chosen. Both state feedback and output feedback direct adaptive controls can guarantee semiglobal uniform boundedness of the closed-loop system signals as rigorously proved by Lyapunov analysis. Numerical simulation results are presented to illustrate the effectiveness of the proposed direct adaptive neural control techniques. © 2012 IEEE.

Kang Z.,Peking University | Kang Z.,Korea Institute for Advanced Study | Ko P.,Korea Institute for Advanced Study | Li T.,CAS Institute of Theoretical Physics | And 2 more authors.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

In the supersymmetric models with low scale supersymmetry (SUSY) breaking where the gravitino mass is around keV, we show that the 3.5 keV X-ray lines can be explained naturally through several different mechanisms: (I) a keV scale dark gaugino plays the role of sterile neutrino in the presence of bilinear R-parity violation. Because the light dark gaugino obtains Majorana mass only via gravity mediation, it is a decaying warm dark matter (DM) candidate; (II) the compressed cold DM states, whose mass degeneracy is broken by gravity mediated SUSY breaking, emit such a line via the heavier one decay into the lighter one plus photon(s). A highly supersymmetric dark sector may readily provide such kind of system; (III) the light axino, whose mass again is around the gravitino mass, decays to neutrino plus gamma in the R-parity violating SUSY. Moreover, we comment on dark radiation from dark gaugino. © 2015 Published by Elsevier B.V.

Li J.L.-W.,University of Electronic Science and Technology of China | Ong W.-L.,National University of Singapore
IEEE Transactions on Antennas and Propagation | Year: 2011

A new solution to electromagnetic scattering by a gyroelectric sphere is obtained. Gyroelectric characteristics are considered, where both internal transmitted fields and external scattered fields are derived theoretically. The derived solutions are capable of dealing with incident electromagnetic waves at an arbitrary incident angle and arbitrary polarization. After the theoretical formulas are obtained, numerical validations are made by comparing our present results with those obtained using the Fourier transform method. Good agreements are observed between the present results obtained in this paper and those obtained using the other method. Some new numerical results are presented to investigate effects of electric anisotropy ratio and gyroelectric ratio on the radar cross section for a gyroelectric sphere and a left-handed metamaterial gyroelectric sphere. The new formulation of the problem is expected to have wide practical applications. In addition, some critical mistakes in literature were corrected. © 2006 IEEE.

Chen X.,University of Electronic Science and Technology of China | Hao G.,City University of Hong Kong | Li L.,Old Dominion University
International Journal of Production Economics | Year: 2014

We investigate a one-period two-echelon supply chain composed of a risk-neutral supplier that produces short life-cycle products and a loss-averse retailer that orders from the supplier via option contracts and sells to end-users with stochastic demand in the selling season. When a single retail season begins, the retailer can obtain goods by purchasing and exercising call options. We derive the loss-averse retailer's optimal ordering policy and the risk-neutral supplier's optimal production policy under these conditions. In addition, we find that the loss-averse retailer may order less than, equal to, or more than the risk-neutral retailer. Further, we show that the loss-averse retailer's optimal order quantity may increase in retail price and decrease in option price and exercise price, which is different from the case of a risk-neutral retailer. Finally, we study coordination of the supply chain and show that there always exists a Pareto contract as compared to the non-coordinating contracts. © 2013 Elsevier B.V.

He L.,Los Alamos National Laboratory | Lu H.,University of Electronic Science and Technology of China | Cao G.,Tsinghua University | Hu H.,Swinburne University of Technology | Liu X.-J.,Swinburne University of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

We present a theoretical study of the ground state of the BCS-BEC crossover in dilute two-dimensional Fermi gases. While the mean-field theory provides a simple and analytical equation of state, the pressure is equal to that of a noninteracting Fermi gas in the entire BCS-BEC crossover, which is not consistent with the features of a weakly interacting Bose condensate in the BEC limit and a weakly interacting Fermi liquid in the BCS limit. The inadequacy of the two-dimensional mean-field theory indicates that the quantum fluctuations are much more pronounced than those in three dimensions. In this work, we show that the inclusion of the Gaussian quantum fluctuations naturally recovers the above features in both the BEC and the BCS limits. In the BEC limit, the missing logarithmic dependence on the boson chemical potential is recovered by the quantum fluctuations. Near the quantum phase transition from the vacuum to the BEC phase, we compare our equation of state with the known grand canonical equation of state of two-dimensional Bose gases and determine the ratio of the composite boson scattering length aB to the fermion scattering length a2D. We find aB≃0.56a2D, in good agreement with the exact four-body calculation. We compare our equation of state in the BCS-BEC crossover with recent results from the quantum Monte Carlo simulations and the experimental measurements and find good agreements. © 2015 American Physical Society.

Peng X.-L.,Shanghai University | Xu X.-J.,Shanghai University | Fu X.,Shanghai University | Zhou T.,University of Electronic Science and Technology of China
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2013

Vaccination is an important measure available for preventing or reducing the spread of infectious diseases. In this paper, an epidemic model including susceptible, infected, and imperfectly vaccinated compartments is studied on Watts-Strogatz small-world, Barabási-Albert scale-free, and random scale-free networks. The epidemic threshold and prevalence are analyzed. For small-world networks, the effective vaccination intervention is suggested and its influence on the threshold and prevalence is analyzed. For scale-free networks, the threshold is found to be strongly dependent both on the effective vaccination rate and on the connectivity distribution. Moreover, so long as vaccination is effective, it can linearly decrease the epidemic prevalence in small-world networks, whereas for scale-free networks it acts exponentially. These results can help in adopting pragmatic treatment upon diseases in structured populations. © 2013 American Physical Society.

Chen M.,Nanjing University of Aeronautics and Astronautics | Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore | How B.V.E.,National University of Singapore | Choo Y.S.,National University of Singapore
IEEE Transactions on Control Systems Technology | Year: 2013

In this paper, robust adaptive control with dynamic control allocation is proposed for the positioning of marine vessels equipped with a thruster assisted mooring system, in the presence of parametric uncertainties, unknown disturbances and input nonlinearities. Using neural network approximation and variable structure based techniques in combination with backstepping and Lyapunov synthesis, the positioning control is developed to handle the uncertainties, input saturation and dead-zone characteristics of the mooring lines and thrusters. Full state feedback with all states measurable and output feedback using high gain observer to estimate unmeasurable states are considered. Dynamic control allocation is presented for actuation of the position mooring system. Under the proposed robust adaptive control, semi-global uniform boundedness of the closed-loop signals are guaranteed. Numerical simulations are carried out to show the effectiveness of the proposed control. © 2012 IEEE.

Yang T.,University of Electronic Science and Technology of China | Chi P.-L.,National Chiao Tung University | Xu R.,University of Electronic Science and Technology of China | Lin W.,University of Electronic Science and Technology of China
IEEE Transactions on Microwave Theory and Techniques | Year: 2013

Composite right/left-handed (CRLH) transmission line structures based on the folded substrate integrated waveguide (FSIW) are presented and discussed in this paper. This FSIW-based CRLH (FSIW-CRLH) transmission line exhibits much lower cut-off frequencies as compared to the ordinary FSIW of the same footprint, and furthermore, it requires only one-half width of the conventional substrate integrated waveguide (SIW) based CRLH (SIW-CRLH) transmission lines while possessing the same dispersion characteristics. In addition, the proposed structure offers the advantage of a high quality factor for preventing the guided-wave circuits from radiation as suffered in the previous open CRLH transmission line structures when operated in the fast-wave region. All of the aforementioned properties lend the proposed FSIW-based CRLH transmission lines best suited to miniaturized and guided-wave microwave applications. In this paper, a comprehensive study on the FSIW-CRLH transmission structures is conducted by means of its dispersion relation and Bloch impedance. In addition, two partial H-plane filters are implemented here to demonstrate the capabilities of miniaturization and high quality factor based on the proposed FSIW-CRLH structures. The resultant filters are shown to have about 80% size reduction as compared to the conventional FSIW filters, and 59% size reduction as compared to the SIW-CRLH filters. To the best of our knowledge, it is the first time that the partial H-plane filters are implemented utilizing both the dispersion behavior of the CRLH transmission structures and the structural benefits of the FSIW configuration. © 1963-2012 IEEE.

Gao P.,Peking University | Wang L.,University of Electronic Science and Technology of China | Zhang Y.,CAS Institute of Physics | Huang Y.,Brookhaven National Laboratory | Liu K.,Peking University
ACS Nano | Year: 2015

For alkali-metal-ion batteries, probing the dynamic processes of ion transport in electrodes is critical to gain insights into understanding how the electrode functions and thus how we can improve it. Here, by using in situ high-resolution transmission electron microscopy, we probe the dynamics of Na transport in MoS2 nanostructures in real-time and compare the intercalation kinetics with previous lithium insertion. We find that Na intercalation follows the two-phase reaction mechanism, that is, trigonal prismatic 2H-MoS2 → octahedral 1T-NaMoS2, and the phase boundary is ∼2 nm thick. The velocity of the phase boundary at <10 nm/s is 1 order smaller than that of lithium diffusion, suggesting sluggish kinetics for sodium intercalation. The newly formed 1T-NaMoS2 contains a high density of defects and series superstructure domains with typical sizes of ∼3-5 nm. Our results provide valuable insights into finding suitable Na electrode materials and understanding the properties of transition metal dichalcogenide MoS2. © 2015 American Chemical Society.

Wang D.,University of Electronic Science and Technology of China | Tang Z.,University of Macau
Advanced Functional Materials | Year: 2015

Raman spectroscopy is the most widely used noninvasive analytical technique. Apart from the fingerprint Raman frequency for identifying vibrational mode of certain functional groups, the Raman scattering tensor can also be used to determine the corresponding vibrational symmetry as well as the orientation of this functional group with respect to the rest of the molecule. For gaseous single molecules, only limited structural information can be obtained from Raman spectroscopy owing to their freely rotating and randomly oriented nature. Here, a method, for the first time, is developed to directly determine the Raman scattering tensor on orientation-fixed single iodine molecules, which are confined inside the nano-sized channels of zeolite AlPO4-11 (AEL) single crystal. The experimental results are in good agreement with theoretical predictions based on a density functional theory. The optical transparency and appreciable size of the crystal facilitate the Raman exploration and the 3D manipulation. It is also demonstrated that iodine molecules' orientations are randomly distributed inside the nano-channels of AlPO4-5 (AFI) crystal, which indicates that by carefully choosing the relevant zeolite crystal, the big family of zeolites can be utilized as directing template database for orienting a large number of guest molecules to estimate their structures by polarized Raman spectroscopy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Li J.L.-W.,University of Electronic Science and Technology of China | Ong W.-L.,National University of Singapore | Zheng K.H.R.,National University of Singapore
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

Solutions for characterizing both electromagnetic wave propagation in, and scattering by, a gyrotropic sphere are obtained based on some recently published literature. Both gyrotropic permittivity and permeability tensors are considered herein, and both transmitted internal fields and scattered external fields are derived theoretically. Compared with problems of a uniaxial sphere, a gyroelectric sphere, and a gyromagnetic sphere, the scattering problem considered here is found to be astonishingly complicated but more generalized in formulation and solution procedure. Numerical validations are made by reducing our results to a gyromagnetic sphere and comparing them with the results obtained using the Fourier transform method, where excellent agreements are observed. Then, radar cross sections (RCSs) versus electric and magnetic gyrotropy ratios are computed, while hybrid effects due to both electric and magnetic gyrotropies are studied extensively, where some special cases of uniaxial spheres are demonstrated. It is shown that characteristics of gyrotropy parameters in Cartesian coordinates may lead to considerably large variations in RCS values, elucidating physical significance of gyrotropy and anisotropy ratios in scattering control. The generalized formulation of the problem is expected to have wide practical applications, while some features of this gyrotropic sphere may help other researchers or engineers to understand more physical insight. In addition, some critical mistakes made in literature were corrected. © 2012 American Physical Society.

Li L.,Old Dominion University | Su Q.,Xi'an Jiaotong University | Chen X.,University of Electronic Science and Technology of China
International Journal of Production Research | Year: 2011

The objective of adopting quality standards such as ISO 9000 series is to help companies develop and maintain supply chain processes that meet certain performance metrics, such as those provided by the Supply Chain Operations Reference model (SCOR). Based on the survey data from 232 companies that have obtained ISO 9000 certification, this study extends the five decision areas (Plan, Source, Make, Deliver, and Return) of the SCOR model by integrating quality assurance measures in the supply chain process. The results show that individually, each decision area has a positive impact on both customer-facing supply chain quality performance and internal-facing firm level business performance. Collectively, 'Plan' and 'Source' decisions are more important to customer-facing supply chain performance (reliability, response, and flexibility), and 'Make' decisions positively affect internal-facing performance metrics (cost and asset). © 2011 Taylor & Francis.

Shen F.,University of Electronic Science and Technology of China | Shen C.,University of Adelaide | Shen C.,Australian Center for Robotic Vision | Liu W.,IBM | Shen H.T.,University of Queensland
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2015

Recently, learning based hashing techniques have attracted broad research interests because they can support efficient storage and retrieval for high-dimensional data such as images, videos, documents, etc. However, a major difficulty of learning to hash lies in handling the discrete constraints imposed on the pursued hash codes, which typically makes hash optimizations very challenging (NP-hard in general). In this work, we propose a new supervised hashing framework, where the learning objective is to generate the optimal binary hash codes for linear classification. By introducing an auxiliary variable, we reformulate the objective such that it can be solved substantially efficiently by employing a regularization algorithm. One of the key steps in this algorithm is to solve a regularization sub-problem associated with the NP-hard binary optimization. We show that the sub-problem admits an analytical solution via cyclic coordinate descent. As such, a high-quality discrete solution can eventually be obtained in an efficient computing manner, therefore enabling to tackle massive datasets. We evaluate the proposed approach, dubbed Supervised Discrete Hashing (SDH), on four large image datasets and demonstrate its superiority to the state-of-the-art hashing methods in large-scale image retrieval. © 2015 IEEE.

Wang X.-H.,University of Electronic Science and Technology of China | Xue Q.,City University of Hong Kong | Choi W.-W.,University of Macau
IEEE Microwave and Wireless Components Letters | Year: 2010

In this letter, double-sided parallel-strip line (DSPSL) has been used to build a novel differential filter with ultra- wideband (UWB) response. Swap structures, based on DSPSL, are employed in the design to realize 180° phase shift. So the swap structures can realize the conversion between differential- and common-mode. Utilizing the characteristic, the input common- mode signals will be cancelled at the center of the filter, while the input differential-mode signals can propagate in the proposed filter. The proposed new differential filter was calculated in analytical method, and was simulated by the full-wave electromagnetic simulator, and was validated by the measurement. The last results show they have a good in-band and out-band performance. With fractional bandwidth of 110% centered at 3 GHz, the differential-mode signals can propagate with UWB frequency response, while the common-mode signals are suppressed below -20 dB in the whole frequency band. © 2010 IEEE.

Tee K.P.,Institute for Infocomm Research | Ren B.,National University of Singapore | Ren B.,University of California at San Diego | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China
Automatica | Year: 2011

This paper presents control design for strict feedback nonlinear systems with time-varying output constraints. An asymmetric time-varying Barrier Lyapunov Function (BLF) is employed to ensure constraint satisfaction. By allowing the barriers to vary with the desired trajectory in time, the initial condition requirements are relaxed. Through a change of tracking error coordinates, we eliminate the explicit dependence of the BLF on time, thereby simplifying the analysis of constraint satisfaction. We show that asymptotic output tracking is achieved without violation of the output constraint, and also quantify the transient performance bound as a function of time that converges to zero. To handle parametric model uncertainty, we present an adaptive controller that ensures constraint satisfaction during the transient phase of online parameter adaptation. The performance of the proposed control is illustrated through a simulation example. © 2011 Elsevier Ltd. All rights reserved.

Chen M.,Nanjing University of Aeronautics and Astronautics | Chen M.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,National University of Singapore | Ren B.,National University of Singapore
Automatica | Year: 2011

In this paper, adaptive tracking control is proposed for a class of uncertain multi-input and multi-output nonlinear systems with non-symmetric input constraints. The auxiliary design system is introduced to analyze the effect of input constraints, and its states are used to adaptive tracking control design. The spectral radius of the control coefficient matrix is used to relax the nonsingular assumption of the control coefficient matrix. Subsequently, the constrained adaptive control is presented, where command filters are adopted to implement the emulate of actuator physical constraints on the control law and virtual control laws and avoid the tedious analytic computations of time derivatives of virtual control laws in the backstepping procedure. Under the proposed control techniques, the closed-loop semi-global uniformly ultimate bounded stability is achieved via Lyapunov synthesis. Finally, simulation studies are presented to illustrate the effectiveness of the proposed adaptive tracking control. © 2011 Elsevier Ltd. All rights reserved.

Guo S.,University of Electronic Science and Technology of China | Huang H.-Z.,University of Electronic Science and Technology of China | Wang Z.,University of Electronic Science and Technology of China | Xie M.,National University of Singapore
IEEE Transactions on Reliability | Year: 2011

There has been quite some research on the development of tools and techniques for grid systems, yet some important issues, e.g., grid service reliability and task scheduling in the grid, have not been sufficiently studied. For some grid services which have large subtasks requiring time-consuming computation, the reliability of grid service could be rather low. To resolve this problem, this paper introduces Local Node Fault Recovery (LNFR) mechanism into grid systems, and presents an in-depth study on grid service reliability modeling and analysis with this kind of fault recovery. To make LNFR mechanism practical, some constraints, i.e. the life times of subtasks, and the numbers of recoveries performed in grid nodes, are introduced; and grid service reliability models under these practical constraints are developed. Based on the proposed grid service reliability model, a multi-objective task scheduling optimization model is presented, and an ant colony optimization (ACO) algorithm is developed to solve it effectively. A numerical example is given to illustrate the influence of fault recovery on grid service reliability, and show a high efficiency of ACO in solving the grid task scheduling problem. © 2010 IEEE.

Liu C.,National University of Singapore | Liu C.,University of Electronic Science and Technology of China | Guo Y.-X.,National University of Singapore | Bao X.,National University of Singapore | Xiao S.-Q.,University of Electronic Science and Technology of China
IEEE Transactions on Antennas and Propagation | Year: 2012

A 60-GHz wideband circularly polarized (CP) helical antenna array of 4 × 4 elements is designed and fabricated using low temperature cofired ceramic (LTCC) technology. The flexible via hole distribution is fully utilized to achieve a helical antenna array to obtain good circular polarization performance. Meanwhile, grounded coplanar waveguide (GCPW) to stripline is utilized for probe station measurement. Unlike traditional helical antennas, the proposed helical antenna array is convenient for integrated applications. The fabricated antenna array has dimension of 12 × 10 × 2 mm 3. The simulated and measured impedance, axial ratio (AR) and radiation pattern are studied and compared. The proposed antenna array shows a wide measured impedance bandwidth from 52.5 to 65.5 GHz for S|11| < -10 dB, wideband measured AR bandwidth from 54 to 66 GHz for AR < 3 dB, respectively. © 2006 IEEE.

Xiao S.-H.,University of Electronic Science and Technology of China | Xiao S.-H.,Yibin University
Wireless Personal Communications | Year: 2012

As one of the most promising techniques for next generation wireless communication, coordinating transmission by multiple points (i.e. radio access points or base stations) have recently attracted a lot of attention because of its potential for intercell co-channel interferencemitigation and significant spectral efficiency improvement. This paper firstly presents the system structure and mathematical signal model for multipoint coordinating downlink transmission, and then gives a detailed discussion on dynamical cell-clustering strategies, scheduling utility-metric and resources allocation scheme in adaptively forming cooperation cluster of cells based on detected system parameters, where the user is serviced by a cluster selected from a set of clusters that has been adapted to its particular network circumstance and location. Some numerical analysis shows that with dynamical cell-clustering, a clustered supercell with 7-cell is relatively reasonable for spectral efficiency improvement. Also, some simulation results are given to showthat adaptive dynamical cell-clustering methods aremore beneficial to user performance improvement. © Springer Science+Business Media, LLC. 2011.

Wang Q.,University of Electronic Science and Technology of China | Leng S.,University of Electronic Science and Technology of China | Fu H.,Oakland University | Zhang Y.,Simula Research Laboratory | Zhang Y.,University of Oslo
IEEE Transactions on Intelligent Transportation Systems | Year: 2012

In recent years, governments, standardization bodies, automobile manufacturers, and academia are working together to develop vehicular ad hoc network (VANET)-based communication technologies. VANETs apply multiple channels, i.e., control channel (CCH) and service channels (SCHs), to provide open public road safety services and the improve comfort and efficiency of driving. Based on the latest standard draft IEEE 802.11p and IEEE 1609.4, this paper proposes a variable CCH interval (VCI) multichannel medium access control (MAC) scheme, which can dynamically adjust the length ratio between CCH and SCHs. The scheme also introduces a multichannel coordination mechanism to provide contention-free access of SCHs. Markov modeling is conducted to optimize the intervals based on the traffic condition. Theoretical analysis and simulation results show that the proposed scheme is able to help IEEE 1609.4 MAC significantly enhance the saturated throughput of SCHs and reduce the transmission delay of service packets while maintaining the prioritized transmission of critical safety information on CCH. © 2011 IEEE.

Yi X.,University of California at Davis | Yi X.,University of Electronic Science and Technology of China | Fontaine N.K.,University of California at Davis | Scott R.P.,University of California at Davis | Yoo S.J.B.,University of California at Davis
Journal of Lightwave Technology | Year: 2010

This paper discusses the realization of terabit per second high speed and high spectral-efficiency optical transmissions using much lower speed electronics and optoelectronics through parallel processing of coherent optical frequency combs at both the transmitter and receiver. The coherent and parallel processing enables electrical-to-optical and optical-to-electrical (E/O and O/E) conversion of wide-bandwidth optical signals which would otherwise exceeds the capability of conventional optoelectronics. In the first experiment, an optical frequency comb (OFC) generator provides 32 comb lines with less than 5-dB power variation. Subsequently, 1.008-Tb/s modulation capability is realized on 32$\,\times\,$ 106 OFDM subcarriers with 16-QAM modulation in a 318-GHz seamless optical bandwidth. It demonstrates an effective way to generate an optical OFDM signal with tens of times wider optical bandwidth than that of analog-to-digital converters and digital-to-analog converters (ADC/DAC). The second experiment demonstrates simultaneous detection of multiple OFDM bands from a 32-band coherent optical OFDM signal using another optical frequency comb, a silica planar lightwave circuit (PLC) that implemented the major optical devices, and two pairs of balanced photodiodes. The experimental results indicate prospects for an optically integrated coherent optical OFDM system on a chip-scale platform. © 2006 IEEE.

Chen X.,University of Electronic Science and Technology of China | Chen X.,International Institute For Applied Systems Analysis | Szolnoki A.,Hungarian Academy of Sciences | Szolnoki A.,Institute of Mathematics | Perc M.,University of Maribor
New Journal of Physics | Year: 2014

Cooperators that refuse to participate in sanctioning defectors create the second-order free-rider problem. Such cooperators will not be punished because they contribute to the public good, but they also eschew the costs associated with punishing defectors. Altruistic punishers - those that cooperate and punish - are at a disadvantage, and it is puzzling how such behaviour has evolved. We show that sharing the responsibility to sanction defectors rather than relying on certain individuals to do so permanently can solve the problem of costly punishment. Inspired by the fact that humans have strong but also emotional tendencies for fair play, we consider probabilistic sanctioning as the simplest way of distributing the duty. In well-mixed populations the public goods game is transformed into a coordination game with full cooperation and defection as the two stable equilibria, while in structured populations pattern formation supports additional counterintuitive solutions that are reminiscent of Parrondos paradox. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Chen W.,Hebei United University | Feng P.,Hebei United University | Lin H.,University of Electronic Science and Technology of China
FEBS Letters | Year: 2012

In this study, we introduced two DNA structural characteristics, namely, bendability and hydroxyl radical cleavage intensity to analyze origin of replication (ORI) in the Saccharomyces cerevisiae genome. We found that both DNA bendability and cleavage intensity in core replication regions were significantly lower than in the linker regions. By using these two DNA structural characteristics, we developed a computational model for ORI prediction and evaluated the model in a benchmark dataset. The predictive performance of the jackknife cross-validation indicates that DNA bendability and cleavage intensity have the ability to describe core replication regions and our model is effective in ORI prediction. © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Wang Z.,Beijing University of Posts and Telecommunications | Peng Q.,University of Electronic Science and Technology of China | Milstein L.B.,University of California at San Diego
IEEE Transactions on Wireless Communications | Year: 2011

In this paper, we consider an adaptive multi-user resource allocation for the downlink transmission of a multi-cluster tactical multicarrier DS CDMA network. The goal is to maximize the sum packet throughput, subject to transmit power constraints. Since the objective function turns out to be noncovex and nondifferentiable, we propose a simple iterative bisection algorithm. At each iteration, a closed-form expression is derived for the transmit power, subchannel, and modulation assignment, which significantly reduces the computational complexity. We also provide an optimization algorithm for the downlink transmission under the condition of imperfect channel knowledge, and investigate the effects of both channel estimation error and partial-band jamming. © 2006 IEEE.

Qin Y.,KTH Royal Institute of Technology | Qin Y.,CAS Institute of Remote Sensing | Li S.,University of Electronic Science and Technology of China | Vu T.-T.,University of Nottingham Malaysia Campus | And 2 more authors.
Optics Express | Year: 2015

Urban land cover map is essential for urban planning, environmental studies and management. This paper aims to demonstrate the potential of geometric and radiometric features derived from LiDAR waveform and point cloud data in urban land cover mapping with both parametric and non-parametric classification algorithms. Small footprint LiDAR waveform data acquired by RIEGL LMS-Q560 in Zhangye city, China is used in this study. A LiDAR processing chain is applied to perform waveform decomposition, range determination and radiometric characterization. With the synergic utilization of geometric and radiometric features derived from LiDAR data, urban land cover classification is then conducted using the Maximum Likelihood Classification (MLC), Support Vector Machines (SVM) and random forest algorithms. The results suggest that the random forest classifier achieved the most accurate result with overall classification accuracy of 91.82% and the kappa coefficient of 0.88. The overall accuracies of MLC and SVM are 84.02, and 88.48, respectively. The study suggest that the synergic utilization of geometric and radiometric features derived from LiDAR data can be efficiently used for urban land cover mapping, the non-parametric random forest classifier is a promising approach for the various features with different physical meanings. © 2015 Optical Society of America.

Li L.,University of California at Berkeley | Li L.,University of Electronic Science and Technology of China | Gratton C.,University of California at Berkeley | Fabiani M.,University of Illinois at Urbana - Champaign | Knight R.T.,University of California at Berkeley
Neurobiology of Aging | Year: 2013

We investigated age-related changes in frontal and parietal scalp event-related potential (ERP) activity during bottom-up and top-down attention. Younger and older participants were presented with arrays constructed to induce either automatic "pop-out" (bottom-up) or effortful "search" (top-down) behavior. Reaction times (RTs) increased and accuracy decreased with age, with a greater age-related decline in accuracy for the search than for the pop-out condition. The latency of the P300 elicited by the visual search array was shorter in both conditions in the younger than in the older adults. Pop-out target detection was associated with greater activity at parietal than at prefrontal locations in younger participants and with a more equipotential prefrontal-parietal distribution in older adults. Search target detection was associated with greater activity at prefrontal than at parietal locations in older relative to younger participants. Thus, aging was associated with a more prefrontal P300 scalp distribution during the control of bottom-up and top-down attention. Early latency extrastriate potentials were enhanced and N2-posterior-contralateral (N2pc) was reduced in the older group, supporting the idea that the frontal enhancements may be due to a compensation for disinhibition and distraction in the older adults. Taken together these findings provide evidence that younger and older adults recruit different frontal-parietal networks during top-down and bottom-up attention, with older adults increasing their recruitment of a more frontally distributed network in both of these types of attention. This work is in accord with previous neuroimaging findings suggesting that older adults recruit more frontal activity in the service of a variety of tasks than younger adults. © 2013 Elsevier Inc.

Zhou Y.,University of Electronic Science and Technology of China | Yang P.,Pacific Northwest National Laboratory | Zu H.,University of Electronic Science and Technology of China | Gao F.,Pacific Northwest National Laboratory | Zu X.,University of Electronic Science and Technology of China
Physical Chemistry Chemical Physics | Year: 2013

Developing approaches to effectively induce and control the magnetic states is critical to the use of magnetic nanostructures in quantum information devices but is still challenging. Here MoS2-based nanostructures including atomic defects, nanoholes, nanodots and antidots are characterized with spin-polarized density functional theory. The S-vacancy defect is more likely to form than the Mo-vacancy defect due to the form of Mo-Mo metallic bonds. Among different shaped nanoholes and nanodots, triangle ones associated with ferromagnetic characteristic are most energetically favorable, and exhibit unexpected large spin moments that scale linearly with edged length. In particular, S-terminated triangle nanodots show strong spin anisotropy around the Fermi level with a substantial collective characteristic of spin states at edges, enabling it to a desired spin-filtering structure. However, in the antidot, the net spin, coupled order and stability of spin states can be engineered by controlling type and distance of internal nanoholes. Based on the analysis of the spin coupled mechanism, a specific antidot structure, the only S-terminated antidot, was determined to exhibit a large net spin with long-range ferromagnetic coupling above room temperature. Given the recent achievement of graphene- and BN-based nanohole, nanodot and antidot structures, we believe that our calculated results are suitable for experimental verification and implementation opening a new path to explore MoS2-based magnetic nanostructures. © 2013 the Owner Societies.

Wu X.-J.,University of Electronic Science and Technology of China | Huang Q.,University of Electronic Science and Technology of China | Zhu X.-J.,Shanghai JiaoTong University
International Journal of Hydrogen Energy | Year: 2011

For a solid oxide fuel cell (SOFC) integrated into a micro gas turbine (MGT) hybrid power system, SOFC operating temperature and turbine inlet temperature are the key parameters, which affect the performance of the hybrid system. Thus, a least squares support vector machine (LS-SVM) identification model based on an improved particle swarm optimization (PSO) algorithm is proposed to describe the nonlinear temperature dynamic properties of the SOFC/MGT hybrid system in this paper. During the process of modeling, an improved PSO algorithm is employed to optimize the parameters of the LS-SVM. In order to obtain the training and prediction data to identify the modified LS-SVM model, a SOFC/MGT physical model is established via Simulink toolbox of MATLAB6.5. Compared to the conventional BP neural network and the standard LS-SVM, the simulation results show that the modified LS-SVM model can efficiently reflect the temperature response of the SOFC/MGT hybrid system. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Gu M.,Pacific Northwest National Laboratory | Wang Z.,Pacific Northwest National Laboratory | Wang Z.,University of Electronic Science and Technology of China | Connell J.G.,Northwestern University | And 4 more authors.
ACS Nano | Year: 2013

Silicon has been widely explored as an anode material for lithium ion battery. Upon lithiation, silicon transforms to amorphous LixSi (a-LixSi) via electrochemical-driven solid-state amorphization. With increasing lithium concentration, a-LixSi transforms to crystalline Li15Si4 (c-Li15Si4). The mechanism of this crystallization process is not known. In this paper, we report the fundamental characteristics of the phase transition of a-LixSi to c-Li15Si4 using in situ scanning transmission electron microscopy, electron energy loss spectroscopy, and density function theory (DFT) calculation. We find that when the lithium concentration in a-LixSi reaches a critical value of x = 3.75, the a-Li3.75Si spontaneously and congruently transforms to c-Li15Si4 by a process that is solely controlled by the lithium concentration in the a-LixSi, involving neither large-scale atomic migration nor phase separation. DFT calculations indicate that c-Li15Si4 formation is favored over other possible crystalline phases due to the similarity in electronic structure with a-Li3.75Si. © 2013 American Chemical Society.

Lin H.,University of Electronic Science and Technology of China | Chen W.,Hebei United University | Ding H.,University of Electronic Science and Technology of China
PLoS ONE | Year: 2013

The structure and activity of enzymes are influenced by pH value of their surroundings. Although many enzymes work well in the pH range from 6 to 8, some specific enzymes have good efficiencies only in acidic (pH<5) or alkaline (pH>9) solution. Studies have demonstrated that the activities of enzymes correlate with their primary sequences. It is crucial to judge enzyme adaptation to acidic or alkaline environment from its amino acid sequence in molecular mechanism clarification and the design of high efficient enzymes. In this study, we developed a sequence-based method to discriminate acidic enzymes from alkaline enzymes. The analysis of variance was used to choose the optimized discriminating features derived from g-gap dipeptide compositions. And support vector machine was utilized to establish the prediction model. In the rigorous jackknife cross-validation, the overall accuracy of 96.7% was achieved. The method can correctly predict 96.3% acidic and 97.1% alkaline enzymes. Through the comparison between the proposed method and previous methods, it is demonstrated that the proposed method is more accurate. On the basis of this proposed method, we have built an online web-server called AcalPred which can be freely accessed from the website (http://lin.uestc.edu.cn/server/AcalPred). We believe that the AcalPred will become a powerful tool to study enzyme adaptation to acidic or alkaline environment. © 2013 Lin et al.

Qu H.,University of Electronic Science and Technology of China | Xing K.,University of Electronic Science and Technology of China | Alexander T.,KTH Royal Institute of Technology
Neurocomputing | Year: 2013

This paper presents a Co-evolutionary Improved Genetic Algorithm (CIGA) for global path planning of multiple mobile robots, which employs a co-evolution mechanism together with an improved genetic algorithm (GA). This improved GA presents an effective and accurate fitness function, improves genetic operators of conventional genetic algorithms and proposes a new genetic modification operator. Moreover, the improved GA, compared with conventional GAs, is better at avoiding the problem of local optimum and has an accelerated convergence rate. The use of a co-evolution mechanism takes into full account the cooperation between populations, which avoids collision between mobile robots and is conductive for each mobile robot to obtain an optimal or near-optimal collision-free path. Simulations are carried out to demonstrate the efficiency of the improved GA and the effectiveness of CIGA. © 2013.

Guo S.-H.,University of Electronic Science and Technology of China | Deng E.-Z.,University of Electronic Science and Technology of China | Xu L.-Q.,University of Electronic Science and Technology of China | Ding H.,University of Electronic Science and Technology of China | And 6 more authors.
Bioinformatics | Year: 2014

Motivation: Nucleosome positioning participates in many cellular activities and plays significant roles in regulating cellular processes. With the avalanche of genome sequences generated in the post-genomic age, it is highly desired to develop automated methods for rapidly and effectively identifying nucleosome positioning. Although some computational methods were proposed, most of them were species specific and neglected the intrinsic local structural properties that might play important roles in determining the nucleosome positioning on a DNA sequence. Results: Here a predictor called 'iNuc-PseKNC' was developed for predicting nucleosome positioning in Homo sapiens, Caenorhabditis elegans and Drosophila melanogaster genomes, respectively. In the new predictor, the samples of DNA sequences were formulated by a novel feature-vector called 'pseudo k-tuple nucleotide composition', into which six DNA local structural properties were incorporated. It was observed by the rigorous cross-validation tests on the three stringent benchmark datasets that the overall success rates achieved by iNuc-PseKNC in predicting the nucleosome positioning of the aforementioned three genomes were 86.27%, 86.90% and 79.97%, respectively. Meanwhile, the results obtained by iNuc-PseKNC on various benchmark datasets used by the previous investigators for different genomes also indicated that the current predictor remarkably outperformed its counterparts. © 2014 The Author 2014.

Hu J.,University of Electronic Science and Technology of China | Hu J.,KTH Royal Institute of Technology | Hu X.,KTH Royal Institute of Technology
Automatica | Year: 2010

Collaborative signal processing and sensor deployment have been among the most important research tasks in target tracking using networked sensors. In this paper, the mathematical model is formulated for single target tracking using mobile nonlinear scalar range sensors. Then a sensor deployment strategy is proposed for the mobile sensors and a nonlinear convergent filter is built to estimate the trajectory of the target. © 2010 Elsevier Ltd. All rights reserved.

Wu Y.I.,University of Electronic Science and Technology of China | Wong K.T.,Hong Kong Polytechnic University | Lau S.-K.,University of Nebraska at Omaha
IEEE Transactions on Signal Processing | Year: 2010

The acoustic vector-sensor is a practical and versatile sound-measurement system, for applications in-room, open-air, or underwater. Its far-field measurement model has been introduced into signal processing over a decade ago; and many direction-finding algorithms have since been developed for acoustic vector-sensors, but only for far-field sources. Missing in the literature is a near-field measurement model for the acoustic vector-sensor. This correspondence fills this literature gap. © 2010 IEEE.

Li Y.,University of Electronic Science and Technology of China | Li Y.,Chongqing University | Celebi H.,Stevens Institute of Technology | Daneshmand M.,University of Electronic Science and Technology of China | And 2 more authors.
IEEE Wireless Communications | Year: 2013

As a promising technique for next-generation wireless networks, femtocells expand the coverage of cellular networks, provide high data rate for users, decrease the transmission power of user equipments, and increase the spectrum efficiency. In a few years, the number of deployed femtocell base stations (FBSs) will reach hundreds of millions. This huge deployment will bring a lot of challenges in terms of interference management, resource scheduling, and energy consumption. In recent years, more and more attention has been paid to energy-efficient communications. The huge number of deployed FBSs will aggravate energy consumption. In this article, we comprehensively survey the related work on energy efficiency issues in femtocell networks, including energy efficiency metrics, energy consumption models, deployments of femtocells, and energy-efficient schemes. Then a simple sleeping scheme, fixed time sleeping, is presented as a case study for saving the energy of FBSs. Some interesting results are also presented to show that fixed time sleeping makes a good trade-off among energy efficiency, actual waiting time, and call loss. © 2013 IEEE.

Lin H.,University of Electronic Science and Technology of China | Chen W.,Hebei United University
Journal of Microbiological Methods | Year: 2011

The thermostability of proteins is particularly relevant for enzyme engineering. Developing a computational method to identify mesophilic proteins would be helpful for protein engineering and design. In this work, we developed support vector machine based method to predict thermophilic proteins using the information of amino acid distribution and selected amino acid pairs. A reliable benchmark dataset including 915 thermophilic proteins and 793 non-thermophilic proteins was constructed for training and testing the proposed models. Results showed that 93.8% thermophilic proteins and 92.7% non-thermophilic proteins could be correctly predicted by using jackknife cross-validation. High predictive successful rate exhibits that this model can be applied for designing stable proteins. © 2010 Elsevier B.V.

Guo S.,Hunan Normal University | Kendrick K.M.,University of Electronic Science and Technology of China | Yu R.,South China Normal University | Wang H.-L.S.,National Taiwan University | And 2 more authors.
Human Brain Mapping | Year: 2014

There is still no clear consensus as to which of the many functional and structural changes in the brain in schizophrenia are of most importance, although the main focus to date has been on those in the frontal and cingulate cortices. In the present study, we have used a novel holistic approach to identify brain-wide functional connectivity changes in medicated schizophrenia patients, and functional connectivity changes were analyzed using resting-state fMRI data from 69 medicated schizophrenia patients and 62 healthy controls. As far as we are aware, this is the largest population reported in the literature for a resting-state study. Voxel-based morphometry was also used to investigate gray and white matter volume changes. Changes were correlated with illness duration/symptom severity and a support vector machine analysis assessed predictive validity. A network involving the inferior parietal lobule, superior parietal gyrus, precuneus, superior marginal, and angular gyri was by far the most affected (68% predictive validity compared with 82% using all connections) and different components correlated with illness duration and positive and negative symptom severity. Smaller changes occurred in emotional memory and sensory and motor processing networks along with weakened interhemispheric connections. Our findings identify the key functional circuitry altered in schizophrenia involving the default network midline cortical system and the cortical mirror neuron system, both playing important roles in sensory and cognitive processing and particularly self-processing, all of which are affected in this disorder. Interestingly, the functional connectivity changes with the strongest links to schizophrenia involved parietal rather than frontal regions. Hum Brain Mapp 35:123-139, 2014. © 2012 Wiley Periodicals, Inc.

Wu X.-J.,University of Electronic Science and Technology of China | Huang Q.,University of Electronic Science and Technology of China | Zhu X.-J.,Shanghai JiaoTong University
Journal of Power Sources | Year: 2011

Solid Oxide Fuel Cell (SOFC) integrated into Micro Gas Turbine (MGT) is a multivariable nonlinear and strong coupling system. To enable the SOFC and MGT hybrid power system to follow the load profile accurately, this paper proposes a self-tuning PID decoupling controller based on a modified output-input feedback (OIF) Elman neural network model to track the MGT output power and SOFC output power. During the modeling, in order to avoid getting into a local minimum, an improved particle swarm optimization (PSO) algorithm is employed to optimize the weights of the OIF Elman neural network. Using the modified OIF Elman neural network identifier, the SOFC/MGT hybrid system is identified on-line, and the parameters of the PID controller are tuned automatically. Furthermore, the corresponding decoupling control law is achieved by the conventional PID control algorithm. The validity and accuracy of the decoupling controller are tested by simulations in MATLAB environment. The simulation results verify that the proposed control strategy can achieve favorable control performance with regard to various load disturbances. © 2010 Elsevier B.V. All rights reserved.

Deng N.,University of Electronic Science and Technology of China | Deng N.,University of Notre Dame | Zhou W.,University of Electronic Science and Technology of China | Haenggi M.,University of Notre Dame
IEEE Transactions on Wireless Communications | Year: 2015

The spatial structure of transmitters in wireless networks plays a key role in evaluating mutual interference and, hence, performance. Although the Poisson point process (PPP) has been widely used to model the spatial configuration of wireless networks, it is not suitable for networks with repulsion. The Ginibre point process (GPP) is one of the main examples of determinantal point processes that can be used to model random phenomena where repulsion is observed. Considering the accuracy, tractability, and practicability tradeoffs, we introduce and promote the β-GPP, which is an intermediate class between the PPP and the GPP, as a model for wireless networks when the nodes exhibit repulsion. To show that the model leads to analytically tractable results in several cases of interest, we derive the mean and variance of the interference using two different approaches: the Palm measure approach and the reduced second-moment approach, and then provide approximations of the interference distribution by three known probability density functions. In addition, to show that the model is relevant for cellular systems, we derive the coverage probability of a typical user and find that the fitted β-GPP can closely model the deployment of actual base stations in terms of coverage probability and other statistics. © 2002-2012 IEEE.

Fang J.,University of Electronic Science and Technology of China | Wen C.,Eastern Illinois University | Prybutok V.,University of North Texas
Computers in Human Behavior | Year: 2014

Investigation of the underlying mechanisms responsible for measurement variance has received little attention. The primary objective of this study is to examine whether paper and social media surveys produce convergent results and investigate the underlying psychological mechanisms for the potential measurement nonequivalence. Particularly, we explored the role of social desirability and satisficing on the measurement results. We collected data via five different survey modes, including paper survey, ad hoc Web survey, online forum (message boards)-based, SNS-based and microblog-based surveys. The findings show that socially desirable responding does not lead to inconsistent results. Rather we found that satisficing causes inconsistent results in paper versus online surveys. Sociability reduces the possibility of engaging in satisficing that results in inconsistent results between traditional Web surveys and social media-based Web surveys. © 2013 Elsevier Ltd. All rights reserved.

Zheng K.,Beijing University of Posts and Telecommunications | Zheng K.,Orange S.A. | Hu F.,Beijing University of Posts and Telecommunications | Wang W.,Catalonia Technology Center of Telecomunications | And 2 more authors.
IEEE Communications Magazine | Year: 2012

Machine-to-machine (M2M) communications are expected to provide ubiquitous connectivity between machines without the need of human intervention. To support such a large number of autonomous devices, the M2M system architecture needs to be extremely power and spectrally efficient. This article thus briefly reviews the features of M2M services in the third generation (3G) long-term evolution and its advancement (LTE-Advanced) networks. Architectural enhancements are then presented for supporting M2M services in LTE-Advanced cellular networks. To increase spectral efficiency, the same spectrum is expected to be utilized for humanto-human (H2H) communications as well as M2M communications. We therefore present various radio resource allocation schemes and quantify their utility in LTE-Advanced cellular networks. System-level simulation results are provided to validate the performance effectiveness of M2M communications in LTE-Advanced cellular networks. © 2012 IEEE.

Zhou Y.,University of Electronic Science and Technology of China | Zhou Y.,Pacific Northwest National Laboratory | Wang Z.,University of Electronic Science and Technology of China | Yang P.,Pacific Northwest National Laboratory | And 4 more authors.
ACS Nano | Year: 2012

Developing approaches to effectively induce and control the magnetic states is critical to the use of magnetic nanostructures in quantum information devices but is still challenging. Here we have demonstrated, by employing the density functional theory calculations, the existence of infinite magnetic sheets with structural integrity and magnetic homogeneity. Examination of a series of transition metal dichalcogenides shows that the biaxial tensile strained NbS2 and NbSe2 structures can be magnetized with a ferromagnetic character due to the competitive effects of through-bond interaction and through-space interaction. The estimated Curie temperatures (387 and 542 K under the 10% strain for NbS2 and NbSe2 structures, respectively) suggest that the unique ferromagnetic character can be achieved above room temperature. The self-exchange of population between 4d orbitals of the Nb atom that leads to exchange splitting is the mechanism behind the transition of the spin moment. The induced magnetic moments can be significantly enhanced by the tensile strain, even giving rise to a half-metallic character with a strong spin polarization around the Fermi level. Given the recent progress in achieving the desired strain on two-dimensional nanostructures, such as graphene and a BN layer, in a controlled way, we believe that our calculated results are suitable for experimental verification and implementation, opening a new path to explore the spintronics in pristine two-dimensional nanostructures. © 2012 American Chemical Society.

Kou G.,University of Electronic Science and Technology of China | Shi Y.,Chinese Academy of Sciences | Shi Y.,University of Nebraska at Omaha | Wang S.,CAS Academy of Mathematics and Systems Science
Decision Support Systems | Year: 2011

Integration of MCDM with DSS brings benefit to both fields. MCDM tools are useful in identifying and evaluating incompatible alternatives for DSS, while DSS can implement MCDM approaches and help maintain and retrieve MCDM models. Over the years, MCDM has made considerable contribution to the development of various DSS subspecialties. This special issue on Multiple Criteria Decision Making and Decision Support Systems consists of 9 selected papers from the 20th International Conference on Multiple Criteria Decision Making. The guest editors highlight the key ideas and contributions of the papers in the special issue. © 2010 Elsevier B.V. All rights reserved.

Levitin G.,University of Electronic Science and Technology of China | Hausken K.,University of Stavanger
Reliability Engineering and System Safety | Year: 2010

The article considers defense resource allocation in a system exposed to external intentional attack. The defender distributes its resource between deploying redundant elements and their protection from attacks. The attacker observes all the elements and tries to detect the unprotected elements. All the detected unprotected elements are destroyed with negligible effort. The attacker then distributes its effort evenly among all of the undetected elements or among elements from a chosen subset of undetected elements. The vulnerability of each element is determined by an attacker-defender contest success function depending on the resources allocated to protection and attack efforts and on the contest intensity. The expected damage caused by the attack is evaluated as system unsupplied demand. The article studies the influence of the unprotected elements' detection probability on the optimal resource distribution. © 2010 Elsevier Ltd. All rights reserved.

Wu X.-J.,University of Electronic Science and Technology of China | Zhu X.-J.,Shanghai JiaoTong University
Journal of Power Sources | Year: 2011

Solid oxide fuel cell and micro gas turbine (SOFC/MGT) hybrid system is a promising distributed power technology. In order to ensure the system safe operation as well as long lifetime of the fuel cell, an effective control manner is expected to regulate the temperature and fuel utilization at the desired level, and track the desired power output. Thus, a multi-loop control strategy for the hybrid system is investigated in this paper. A mathematical model for the SOFC/MGT hybrid system is built firstly. Based on the mathematical model, control cycles are introduced and their design is discussed. Part load operation condition is employed to investigate the control strategies for the system. The dynamic modeling and control implementation are realized in the MATLAB/SIMULINK environment, and the simulation results show that it is feasible to build the multi-loop control methods for the SOFC/MGT hybrid system with regard to load disturbances. © 2011 Elsevier B.V. All rights reserved.

Liu Y.,University of Electronic Science and Technology of China | Yu Y.,University of Illinois at Urbana - Champaign
IEEE Transactions on Visualization and Computer Graphics | Year: 2012

In this paper, we present a robust and accurate algorithm for interactive image segmentation. The level set method is clearly advantageous for image objects with a complex topology and fragmented appearance. Our method integrates discriminative classification models and distance transforms with the level set method to avoid local minima and better snap to true object boundaries. The level set function approximates a transformed version of pixelwise posterior probabilities of being part of a target object. The evolution of its zero level set is driven by three force terms, region force, edge field force, and curvature force. These forces are based on a probabilistic classifier and an unsigned distance transform of salient edges. We further propose a technique that improves the performance of both the probabilistic classifier and the level set method over multiple passes. It makes the final object segmentation less sensitive to user interactions. Experiments and comparisons demonstrate the effectiveness of our method. © 2012 IEEE.

Kou G.,University of Electronic Science and Technology of China | Lu Y.,University of Electronic Science and Technology of China | Peng Y.,University of Electronic Science and Technology of China | Shi Y.,University of Nebraska at Omaha | Shi Y.,Chinese Academy of Sciences
International Journal of Information Technology and Decision Making | Year: 2012

Classification algorithm selection is an important issue in many disciplines. Since it normally involves more than one criterion, the task of algorithm selection can be modeled as multiple criteria decision making (MCDM) problems. Different MCDM methods evaluate classifiers from different aspects and thus they may produce divergent rankings of classifiers. The goal of this paper is to propose an approach to resolve disagreements among MCDM methods based on Spearman's rank correlation coefficient. Five MCDM methods are examined using 17 classification algorithms and 10 performance criteria over 11 public-domain binary classification datasets in the experimental study. The rankings of classifiers are quite different at first. After applying the proposed approach, the differences among MCDM rankings are largely reduced. The experimental results prove that the proposed approach can resolve conflicting MCDM rankings and reach an agreement among different MCDM methods. © 2012 World Scientific Publishing Company.

Liu N.,University of Electronic Science and Technology of China | Liu M.,University of Electronic Science and Technology of China | Chen G.,Shanghai JiaoTong University | Cao J.,Hong Kong Polytechnic University
Proceedings - IEEE INFOCOM | Year: 2012

In Vehicular Ad Hoc Networks (VANETs), content distribution directly relies on the fleeting and dynamic contacts between moving vehicles, which often leads to prolonged downloading delay and terrible user experience. Deploying Wifi-based Access Points (APs) could relieve this problem, but it often requires a large amount of investment, especially at the city scale. In this paper, we propose the idea of ParkCast, which doesn't need investment, but leverages roadside parking to distribute contents in urban VANETs. With wireless device and rechargable battery, parked vehicles can communicate with any vehicles driving through them. Owing to the extensive parking in cities, available resources and contact opportunities for sharing are largely increased. To each road, parked vehicles at roadside are grouped into a line cluster as far as possible, which is locally coordinated for node selection and data transmission. Such a collaborative design paradigm exploits the sequential contacts between moving vehicles and parked ones, implements sequential file transfer, reduces unnecessary messages and collisions, and then expedites content distribution greatly. We investigate ParkCast through theoretic analysis and realistic survey and simulation. The results prove that our scheme achieve high performance in distribution of contents with different sizes, especially in sparse traffic conditions. © 2012 IEEE.

Wu X.-J.,University of Electronic Science and Technology of China | Zhu X.-J.,Shanghai JiaoTong University
International Journal of Energy Research | Year: 2013

For a solid oxide fuel cell (SOFC) and micro gas turbine (MGT) hybrid system, optimal control of load changes requires optimal dynamic scheduling of set points for the system's controllers. Thus, this paper proposes an improved iterative particle swarm optimization (PSO) algorithm to optimize the operating parameters under various loads. This method combines the iteration method and the PSO algorithm together, which can execute the discrete PSO iteratively until the control profile would converge to an optimal one. In MATLAB environment, the simulation results show that the SOFC/MGT hybrid model with the optimized parameters can effectively track the output power with high efficiency. Hence, the improved iterative PSO algorithm can be helpful for system analysis, optimization design, and real-time control of the SOFC/MGT hybrid system. © 2011 John Wiley & Sons, Ltd.

Yan S.,University of Electronic Science and Technology of China | Yan S.,University of Illinois at Urbana - Champaign | Jin J.-M.,University of Illinois at Urbana - Champaign | Nie Z.,University of Electronic Science and Technology of China
IEEE Transactions on Antennas and Propagation | Year: 2011

In computational electromagnetics, the second-kind Fredholm integral equations are known to have very fast iterative convergence but rather poor solution accuracy compared with the first-kind Fredholm integral equations. The error source of the second-kind integral equations can mainly be attributed to the discretization error of the identity operators. In this paper, a scheme is presented to significantly suppress such discretization error by using the Buffa-Christiansen functions as the testing function, leading to much more accurate solutions of the second-kind integral equations, while maintaining their fast convergence properties. Numerical experiments are designed to investigate and demonstrate the accuracy improvement of the second-kind surface integral equations in both perfect electric conductor and dielectric cases by using the presented discretization scheme. © 2006 IEEE.

Chen W.,Hebei United University | Chen W.,Gordon Life Science Institute | Feng P.-M.,Hebei United University | Lin H.,University of Electronic Science and Technology of China | Chou K.-C.,Gordon Life Science Institute
Nucleic Acids Research | Year: 2013

Meiotic recombination is an important biological process. As a main driving force of evolution, recombination provides natural new combinations of genetic variations. Rather than randomly occurring across a genome, meiotic recombination takes place in some genomic regions (the so-called 'hotspots') with higher frequencies, and in the other regions (the so-called 'coldspots') with lower frequencies. Therefore, the information of the hotspots and coldspots would provide useful insights for in-depth studying of the mechanism of recombination and the genome evolution process as well. So far, the recombination regions have been mainly determined by experiments, which are both expensive and time-consuming. With the avalanche of genome sequences generated in the postgenomic age, it is highly desired to develop automated methods for rapidly and effectively identifying the recombination regions. In this study, a predictor, called 'iRSpot-PseDNC', was developed for identifying the recombination hotspots and coldspots. In the new predictor, the samples of DNA sequences are formulated by a novel feature vector, the so-called 'pseudo dinucleotide composition' (PseDNC), into which six local DNA structural properties, i.e. three angular parameters (twist, tilt and roll) and three translational parameters (shift, slide and rise), are incorporated. It was observed by the rigorous jackknife test that the overall success rate achieved by iRSpot-PseDNC was >82% in identifying recombination spots in Saccharomyces cerevisiae, indicating the new predictor is promising or at least may become a complementary tool to the existing methods in this area. Although the benchmark data set used to train and test the current method was from S. cerevisiae, the basic approaches can also be extended to deal with all the other genomes. Particularly, it has not escaped our notice that the PseDNC approach can be also used to study many other DNA-related problems. As a user-friendly web-server, iRSpot-PseDNC is freely accessible at http://lin.uestc.edu. cn/server/iRSpot- PseDNC. © The Author(s) 2013. Published by Oxford University Press.

Cao H.,University of Electronic Science and Technology of China | He W.,University of Electronic Science and Technology of China | Mao Y.,China Academy of Engineering Physics | Lin X.,University of Chinese Academy of Sciences | And 3 more authors.
Journal of Power Sources | Year: 2014

Stability is of paramount importance in organic semiconductor devices, especially in organic solar cells (OSCs). Serious degradation in air limits wide applications of these flexible, light-weight and low-cost power-generation devices. Studying the stability of organic solar cells will help us understand degradation mechanisms and further improve the stability of these devices. There are many investigations into the efficiency and stability of OSCs. The efficiency and stability of devices even of the same photoactive materials are scattered in different papers. In particular, the extrinsic degradation that mainly occurs near the interface between the organic layer and the cathode is a major stability concern. In the past few years, researchers have developed many new cathodes and cathode buffer layers, some of which have astonishingly improved the stability of OSCs. In this review article, we discuss the recent developments of these materials and summarize recent progresses in the study of the degradation/stability of OSCs, with emphasis on the extrinsic degradation/stability that is related to the intrusion of oxygen and water. The review provides detailed insight into the current status of research on the stability of OSCs and seeks to facilitate the development of highly-efficient OSCs with enhanced stability. © 2014 Elsevier B.V. All rights reserved.

Zhong Y.,University of Electronic Science and Technology of China | Zhang W.,University of Electronic Science and Technology of China | Haenggi M.,University of Notre Dame
IEEE Transactions on Wireless Communications | Year: 2014

The capacity of wireless networks is fundamentally limited by interference. However, little research has focused on the interference correlation, which may greatly increase the local delay (namely the number of time slots required for a node to successfully transmit a packet). This paper focuses on the question whether increasing randomness in the MAC, specifically frequency-hopping multiple access (FHMA) and ALOHA, helps to reduce the effect of interference correlation. We derive closed-form results for the mean and variance of the local delay for the two MAC protocols and evaluate the optimal parameters that minimize the mean local delay. Based on the optimal parameters, we identify two operating regimes, the correlation-limited regime and the bandwidth-limited regime. Our results reveal that while the mean local delays for FHMA with N sub-bands and for ALOHA with transmit probability p essentially coincide when p=\frac{1}{N}, a fundamental discrepancy exists between their variances. We also discuss implications from the analysis, including an interesting mean delay-jitter tradeoff, and convenient bounds on the tail probability of the local delay, which shed useful insights into system design. © 2002-2012 IEEE.

Chen W.,Hebei United University | Feng P.,Hebei United University | Lin H.,University of Electronic Science and Technology of China
Journal of Industrial Microbiology and Biotechnology | Year: 2012

Ketoacyl synthases are enzymes involved in fatty acid synthesis and can be classified into five families based on primary sequence similarity. Different families have different catalytic mechanisms. Developing costeffective computational models to identify the family of ketoacyl synthases will be helpful for enzyme engineering and in knowing individual enzymes' catalytic mechanisms. In this work, a support vector machine-based method was developed to predict ketoacyl synthase family using the n-peptide composition of reduced amino acid alphabets. In jackknife cross-validation, the model based on the 2-peptide composition of a reduced amino acid alphabet of size 13 yielded the best overall accuracy of 96.44% with average accuracy of 93.36%, which is superior to other state-of-the-art methods. This result suggests that the information provided by n-peptide compositions of reduced amino acid alphabets provides efficient means for enzyme family classification and that the proposed model can be efficiently used for ketoacyl synthase family annotation. © Society for Industrial Microbiology 2011.

Guo D.,University of Electronic Science and Technology of China | Guo D.,Okinawa Institute of Science and Technology | Wang Q.,Beihang University | Perc M.,University of Maribor
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

Networks of fast-spiking interneurons are crucial for the generation of neural oscillations in the brain. Here we study the synchronous behavior of interneuronal networks that are coupled by delayed inhibitory and fast electrical synapses. We find that both coupling modes play a crucial role by the synchronization of the network. In addition, delayed inhibitory synapses affect the emerging oscillatory patterns. By increasing the inhibitory synaptic delay, we observe a transition from regular to mixed oscillatory patterns at a critical value. We also examine how the unreliability of inhibitory synapses influences the emergence of synchronization and the oscillatory patterns. We find that low levels of reliability tend to destroy synchronization and, moreover, that interneuronal networks with long inhibitory synaptic delays require a minimal level of reliability for the mixed oscillatory pattern to be maintained. © 2012 American Physical Society.

Wang W.,University of Electronic Science and Technology of China | Tang M.,University of Electronic Science and Technology of China | Tang M.,Kyungpook National University | Yang H.,University of Electronic Science and Technology of China | And 3 more authors.
Scientific Reports | Year: 2014

The spread of disease through a physical-contact network and the spread of information about the disease on a communication network are two intimately related dynamical processes. We investigate the asymmetrical interplay between the two types of spreading dynamics, each occurring on its own layer, by focusing on the two fundamental quantities underlying any spreading process: epidemic threshold and the final infection ratio. We find that an epidemic outbreak on the contact layer can induce an outbreak on the communication layer, and information spreading can effectively raise the epidemic threshold. When structural correlation exists between the two layers, the information threshold remains unchanged but the epidemic threshold can be enhanced, making the contact layer more resilient to epidemic outbreak. We develop a physical theory to understand the intricate interplay between the two types of spreading dynamics.

Lin H.,University of Electronic Science and Technology of China | Lin H.,Gordon Life Science Institute | Deng E.-Z.,University of Electronic Science and Technology of China | Ding H.,University of Electronic Science and Technology of China | And 4 more authors.
Nucleic Acids Research | Year: 2014

The σ54 promoters are unique in prokaryotic genome and responsible for transcripting carbon and nitrogen-related genes. With the avalanche of genome sequences generated in the postgenomic age, it is highly desired to develop automated methods for rapidly and effectively identifying the σ54 promoters. Here, a predictor called 'iPro54-PseKNC' was developed. In the predictor, the samples of DNA sequences were formulated by a novel feature vector called 'pseudo k-tuple nucleotide composition', which was further optimized by the incremental feature selection procedure. The performance of iPro54-PseKNC was examined by the rigorous jackknife cross-validation tests on a stringent benchmark data set. As a user-friendly web-server, iPro54-PseKNC is freely accessible at http://lin.uestc.edu.cn/server/iPro54-PseKNC. For the convenience of the vast majority of experimental scientists, a step-by-step protocol guide was provided on how to use the web-server to get the desired results without the need to follow the complicated mathematics that were presented in this paper just for its integrity. Meanwhile, we also discovered through an in-depth statistical analysis that the distribution of distances between the transcription start sites and the translation initiation sites were governed by the gamma distribution, which may provide a fundamental physical principle for studying the σ54 promoters. © 2014 The Author(s).

Tian Y.,University of Electronic Science and Technology of China | Tian Y.,Chongqing University of Posts and Telecommunications | Yao D.,University of Electronic Science and Technology of China
Psychophysiology | Year: 2013

Using ERPs in the audiovisual stimulus, the current study is the first to investigate the influence of the reference on experimental effects (between two conditions). Three references, the average reference (AR), the mean mastoid (MM), and a new infinity zero reference (IR), were comparatively investigated via ERPs, statistical parametric scalp mappings (SPSM), and LORETA. Specifically, for the N1 (170-190ms), the SPSM results showed an anterior distribution for MM, a posterior distribution for IR, and both anterior and posterior distributions for AR. However, the circumstantial evidence provided by LORETA is consistent with SPSM of IR. These results indicated that the newly developed IR could provide increased accuracy; thus, we recommend IR for future ERP studies. © 2013 Society for Psychophysiological Research.

Chen W.,Hebei United University | Lin H.,University of Electronic Science and Technology of China
Computers in Biology and Medicine | Year: 2012

Proteins belonging to different subfamilies of Voltage-gated K + channels (VKC) are functionally divergent. The traditional method to classify ion channels is more time consuming. Thus, it is highly desirable to develop novel computational methods for VKC subfamily classification. In this study, a support vector machine based method was proposed to predict VKC subfamilies using amino acid and dipeptide compositions. In order to remove redundant information, a novel feature selection technique was employed to single out optimized features. In the jackknife cross-validation, the proposed method (VKCPred) achieved an overall accuracy of 93.09% with 93.22% average sensitivity and 98.34% average specificity, which are superior to that of other two state-of-the-art classifiers. These results indicate that VKCPred can be efficiently used to identify and annotate voltage-gated K + channels' subfamilies. The VKCPred software and dataset are freely available at http://cobi.uestc.edu.cn/people/hlin/tools/VKCPred/. © 2012 Elsevier Ltd.

Luojie X.,University of Electronic Science and Technology of China | Kurkoski B.M.,University of Electro - Communications
2012 International Conference on Computing, Networking and Communications, ICNC'12 | Year: 2012

Agarwal et al. gave a closed-form expression for write amplification in NAND flash memory by finding the probability of a page being valid over the whole flash memory. This paper gives an improved analytic expression for write amplification in NAND flash memory by finding the probability of a page being invalid in the block selected for garbage collection. The improved expression uses the Lambert W function. Through asymptotic analysis, write amplification is shown to depend on the overprovisioning factor only, consistent with the previous work. Comparison with numerical simulations shows that the improved expression achieves a more accurate prediction of write amplification. For example, when the overprovisioning factor is 0.3, the improved expression gives a write amplification of 2.36 whereas that of the previous work gives 2.17, when the actual value is 2.35. © 2012 IEEE.

Chen Y.P.,University of Electronic Science and Technology of China | Chew W.C.,University of Illinois at Urbana - Champaign | Jiang L.,University of Hong Kong
IEEE Transactions on Antennas and Propagation | Year: 2012

A new Green's function formulation is developed systematically for modeling general homogeneous (dielectric or magnetic) objects in a layered medium. The dyadic form of the Green's function is first derived based on the pilot vector potential approach. The matrix representation in the moment method implementation is then derived by applying integration by parts and vector identities. The line integral issue in the matrix representation is investigated, based on the continuity property of the propagation factor and the consistency of the primary term and the secondary term. The extinction theorem is then revisited in the inhomogeneous background and a surface integral equation for general homogeneous objects is set up. Different from the popular mixed potential integral equation formulation, this method avoids the artificial definition of scalar potential. The singularity of the matrix representation of the Green's function can be made as weak as possible. Several numerical results are demonstrated to validate the formulation developed in this paper. Finally, the duality principle of the layered medium Green's function is discussed in the appendix to make the formulation succinct. © 1963-2012 IEEE.

Hale G.,Federal Reserve Bank of San Francisco | Long C.,Colgate University | Long C.,University of Electronic Science and Technology of China
Pacific Economic Review | Year: 2011

We review previous literature on productivity spillovers of foreign direct investment (FDI) in China and conduct our own analysis using a firm-level data set from a World Bank survey. We find that the evidence of FDI spillovers on the productivity of Chinese domestic firms is mixed, with many positive results largely due to aggregation bias or failure to control for endogeneity of FDI. Attempting over 6000 specifications that take into account forward and backward linkages, we fail to find evidence of systematic positive productivity spillovers from FDI in China. © 2011 The Authors. Pacific Economic Review © 2011 Blackwell Publishing Asia Pty Ltd.

Chen W.,Hebei United University | Chen W.,Gordon Life Science Institute | Lin H.,University of Electronic Science and Technology of China | Feng P.-M.,Hebei United University | And 3 more authors.
PLoS ONE | Year: 2012

Nucleosome positioning has important roles in key cellular processes. Although intensive efforts have been made in this area, the rules defining nucleosome positioning is still elusive and debated. In this study, we carried out a systematic comparison among the profiles of twelve DNA physicochemical features between the nucleosomal and linker sequences in the Saccharomyces cerevisiae genome. We found that nucleosomal sequences have some position-specific physicochemical features, which can be used for in-depth studying nucleosomes. Meanwhile, a new predictor, called iNuc-PhysChem, was developed for identification of nucleosomal sequences by incorporating these physicochemical properties into a 1788-D (dimensional) feature vector, which was further reduced to a 884-D vector via the IFS (incremental feature selection) procedure to optimize the feature set. It was observed by a cross-validation test on a benchmark dataset that the overall success rate achieved by iNuc-PhysChem was over 96% in identifying nucleosomal or linker sequences. As a web-server, iNuc-PhysChem is freely accessible to the public at http://lin.uestc.edu.cn/server/iNuc-PhysChem. For the convenience of the vast majority of experimental scientists, a step-by-step guide is provided on how to use the web-server to get the desired results without the need to follow the complicated mathematics that were presented just for the integrity in developing the predictor. Meanwhile, for those who prefer to run predictions in their own computers, the predictor's code can be easily downloaded from the web-server. It is anticipated that iNuc-PhysChem may become a useful high throughput tool for both basic research and drug design. © 2012 Chen et al.

Ge S.S.,University of Electronic Science and Technology of China | Li Z.,Shanghai JiaoTong University | Li Z.,Key Laboratory of System Control and Information Processing | Yang H.,Zhejiang University
IEEE Transactions on Control Systems Technology | Year: 2012

Fundamentally, control system designs are concerned with the flow of signals in the closed loop. In this paper, we are to present the control technique at the next level of abstraction in control system design. We construct a control using implicit function with support vector regression-based data-driven model for the biped, in the presence of parametric and functional dynamics uncertainties. Based on Lyapunov synthesis, we develop decoupled adaptive control based on the model predictive and the data-driven techniques and construct the control directly from online or offline data. The adaptive predictive control mechanisms use the advantage of data-driven technique combined with online parameters estimation strategy in order to achieve an efficient approximation. Simulation results are presented to verify the effectiveness of the proposed control. © 2011 IEEE.

Ke Q.,University of Electronic Science and Technology of China | Oommen B.J.,Carleton University
Neurocomputing | Year: 2014

The goal of this paper is to catalog the chaotic and Pattern Recognition (PR) properties of a network of Logistic Neurons (LNs). Over the last few years, the field of Chaotic Neural Networks (CNNs) has been extensively studied because of their potential applications in PR, Associative Memory (AM), optimization, multi-value content addressing and image processing. The research in chaos theory has thus expanded to report numerous neural models that, by virtue of their inter-connections, yield chaotic behavior. Recently, the Adachi Neural Network (AdNN) and its variants have been shown to yield an entire spectrum of properties including chaotic, quasi-chaotic, PR and AM as its/their parameters change. To simplify the AdNN model and to also investigate the design philosophy of the CNN model, in this paper, we consider the consequences of networking a set of LNs, each of which is founded on principles of the Logistic map. By appropriately defining the input/output characteristics of a fully connected network of LNs, and by defining their set of weights and output functions, we have succeeded in designing a Logistic Neural Network (LNN). Although the LNN is much simpler than other CNNs such as the AdNN, it possesses some of those properties mentioned above. The chaotic properties of a single-neuron have been formally proven using the theory of Lyapunov analysis and by examining its Jacobian matrix. As far as we know, the results presented here, that the LNN can also demonstrate both AM and PR properties, are unreported, and we submit that it can, hopefully, lead to a new method of PR and AM. © 2013 Elsevier B.V.

Patent
University of Electronic Science, Technology of China and Huawei Symantec Technologies | Date: 2012-02-03

A multi-disk fault-tolerant system, a method for generating a check block, and a method for recovering a data block are provided. The multi-disk fault-tolerant system includes a disk array and a calculation module connected through a system bus, the disk array is formed by p disks, and a fault-tolerant disk amount of the disk array is q; data in the disk array is arranged according to a form of a matrix M of (m+q)p, where m is a prime number smaller than or equal to pq; in the matrix M, a 0^(th )row is virtual data blocks being virtual and having values being 0, a 1^(st )row to an (m1)^(th )row are data blocks, an m^(th )row to an (m+q1)^(th )row are check blocks. Therefore, during a procedure of generating the check block and recovering the data block in the multi-disk fault-tolerant system, calculation complexity is lowered.

Ding H.,University of Electronic Science and Technology of China | Feng P.-M.,Hebei United University | Chen W.,Hebei United University | Lin H.,University of Electronic Science and Technology of China
Molecular BioSystems | Year: 2014

The bacteriophage virion proteins play extremely important roles in the fate of host bacterial cells. Accurate identification of bacteriophage virion proteins is very important for understanding their functions and clarifying the lysis mechanism of bacterial cells. In this study, a new sequence-based method was developed to identify phage virion proteins. In the new method, the protein sequences were initially formulated by the g-gap dipeptide compositions. Subsequently, the analysis of variance (ANOVA) with incremental feature selection (IFS) was used to search for the optimal feature set. It was observed that, in jackknife cross-validation, the optimal feature set including 160 optimized features can produce the maximum accuracy of 85.02%. By performing feature analysis, we found that the correlation between two amino acids with one gap was more important than other correlations for phage virion protein prediction and that some of the 1-gap dipeptides were important and mainly contributed to the virion protein prediction. This analysis will provide novel insights into the function of phage virion proteins. On the basis of the proposed method, an online web-server, PVPred, was established and can be freely accessed from the website (http://lin.uestc.edu.cn/server/PVPred). We believe that the PVPred will become a powerful tool to study phage virion proteins and to guide the related experimental validations. This journal is © the Partner Organisations 2014.

Feng P.,Hebei United University | Chen W.,Hebei United University | Lin H.,University of Electronic Science and Technology of China
Genomics | Year: 2014

As an inheritable epigenetic modification, DNA methylation plays important roles in many biological processes. The non-uniform distribution of DNA methylation across the genome implies that characterizing genome-wide DNA methylation patterns is necessary to better understand the regulatory mechanisms of DNA methylation. Although a series of experimental technologies have been proposed, they are cost-ineffective for DNA methylation status detection. As complements to experimental techniques, computational methods will facilitate the identification of DNA methylation status. In the present study, we proposed a Naïve Bayes model to predict CpG island methylation status. In this model, DNA sequences are formulated by "pseudo trinucleotide composition" into which three DNA physicochemical properties were incorporated. It was observed by the jack-knife test that the overall success rate achieved by the proposed model in predicting the DNA methylation status was 88.22%. This result indicates that the proposed model is a useful tool for DNA methylation status prediction. © 2014 Elsevier Inc.

News Article | October 13, 2016
Site: www.materialstoday.com

In optoelectronic devices like solar cells or light-emitting diodes, the band gap – or energy gap between the top of the valence band and the bottom of the conduction band – determines the photonic performance. One of the ways of controlling that band gap is through strain because deforming a material induces a predictable change in the band gap. GaAs, which is widely used in optoelectronic devices, is too brittle for such simple strain engineering. But now researchers from the University of Electronic Science and Technology of China, Tsinghua University, and the Institute of Semiconductors in Beijing have found a way around the problem. By creating very thin ribbons of GaAs, or nanoribbons, the researchers introduce a wave or buckle into the structure that allows manipulation of the band gap [Wang et al., ACS Nano (2016), doi: 10.1021/acsnano.6b03434]. The team led by Xue Feng of Tsinghua University created the wavy nanoribbons by using photolithography to cut thin strips of GaAs grown by metal-organic chemical vapor deposition (MOCVD). The nanoribbons are then transfer-printed onto a pre-stretched soft substrate of the polymer polydimethylsiloxane (PDMS). When the stretched substrate is released, ribbons of undulating GaAs are formed. The wavy structure creates alternating regions of tension and compression in the nanoribbons. In step with this strain variation, the band gap narrows and widens periodically and continuously along the length ofthe structure. Photoluminescence (PL) measurements provide a direct insight into the band gap. Over a distance of 100 m in a single nanoribbon, the researchers found that the band gap varies by up to ∼1%. “Our approach can produce continuous strain in the same piece of material, from tension to compression, making its performance unique,” says Feng. The ability to control the band gap in such a predictable and periodic way within a nanostructure could inspire new designs of optical and optoelectronic devices, suggest the researchers. Because of the overall flexibility of the GaAs nanoribbons, further levels of complexity in the modulation and enhancement of the band gap can be achieved through tension or compression of the soft substrate. “We are intending to induce more complicated strain into the optoelectronic material,” Feng explains. “[For example] we could divide the whole ribbon into several parts with different band gaps to make separate LED cells. Every cell would have a different emitting wavelength based on its gap - we could achieve a multi-wavelength LED device using a single film.” John A. Rogers of the University of Illinois at Urbana-Champaign believes that Feng and colleagues have made very interesting use of mechanical buckling in semiconductor nanoribbons to scrutinize the effects of strain on electronic bandgap. “The work is an interesting combination of nanoscale mechanics and electronic structure, where the unique ‘wavy’ geometry of the materials allows systematic investigation of how strain and intrinsic properties relevant to electronic and optoelectronic performance can be examined at sub-micron length scales,” he says. “The outcomes have relevance to engineering design of both conventional, wafer-based forms of semiconductor devices as well as newer stretchable and flexible technologies.” This article was originally published in Nano Today (2016), doi:10.1016/j.nantod.2016.08.002

Lu Q.,University of Electronic Science and Technology of China | Lu Q.,Basque Center for Applied Mathematics
ESAIM - Control, Optimisation and Calculus of Variations | Year: 2013

In this paper, a lower bound is established for the local energy of partial sum of eigenfunctions for Laplace-Beltrami operators (in Riemannian manifolds with low regularity data) with general boundary condition. This result is a consequence of a new pointwise and weighted estimate for Laplace-Beltrami operators, a construction of some nonnegative function with arbitrary given critical point location in the manifold, and also two interpolation results for solutions of elliptic equations with lateral Robin boundary conditions. © 2012 EDP Sciences, SMAI.

Jiang C.,University of Electronic Science and Technology of China | Li H.,Stevens Institute of Technology | Rangaswamy M.,U.S. Air force
IEEE Transactions on Signal Processing | Year: 2012

The conjugate gradient (CG) algorithm is an efficient method for the calculation of the weight vector of the matched filter (MF). As an iterative algorithm, it produces a series of approximations to the MF weight vector, each of which can be used to filter the test signal and form a test statistic. This effectively leads to a family of detectors, referred to as the CG-MF detectors, which are indexed by k the number of iterations incurred. We first consider a general case involving an arbitrary covariance matrix of the disturbance (including interference, noise, etc.) and show that all CG-MF detectors attain constant false alarm rate (CFAR) and, furthermore, are optimum in the sense that the kth CG-MF detector yields the highest output signal-to-interference-and- noise ratio (SINR) among all linear detectors within the k th Krylov subspace. We then consider a structured case frequently encountered in practice, where the covariance matrix of the disturbance contains a low-rank component (rank-r) due to dominant interference sources, a scaled identity due to the presence of a white noise, and a perturbation component containing the residual interference. We show that the (r+1)st CG-MF detector achieves CFAR and an output SINR nearly identical to that of the MF detector which requires complete iterations of the CG algorithm till reaching convergence. Hence, the (r+1)st CG-MF detector can be used in place of the MF detector for significant computational saving when r is small. Numerical results are presented to verify the accuracy of our analysis for the CG-MF detectors. © 1991-2012 IEEE.

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.

Lin P.,University of Electronic Science and Technology of China | Lin P.,Beihang University | Jia Y.,Beihang University
Automatica | Year: 2011

This paper investigates consensus problems in networks of continuous-time agents with diverse time-delays and jointly-connected topologies. For convergence analysis of the networks, a class of LyapunovKrasovskii functions is constructed which contains two parts: one describes the current disagreement dynamics and the other describes the integral impact of the dynamics of the whole network over the past. By a contradiction approach, sufficient conditions are derived under which all agents reach consensus, even though the communication structures between agents dynamically change over time and the corresponding graphs may not be connected. The obtained conditions are composed of a sum of decoupled parts corresponding to each possible connected component of the communication topology. Finally, numerical examples are included to illustrate the obtained results. Copyright © 2011 Published by Elsevier Ltd. All rights reserved.

Huang Y.,University of Electronic Science and Technology of China | Wen G.,University of Electronic Science and Technology of China | Zhu W.,Monash University | Li J.,University of Electronic Science and Technology of China | And 2 more authors.
Optics Express | Year: 2014

We synthesize and systematically characterize a novel type of magnetically tunable metamaterial absorber (MA) by integrating ferrite as a substrate or superstrate into a conventional passive MA. The nearly perfect absorption and tunability of this device is studied both numerically and experimentally within X-band (8-12 GHz) in a rectangular waveguide setup. Our measurements clearly show that the resonant frequency of the MA can be shifted across a wide frequency band by continuous adjustment of a magnetic field acting on the ferrite. Moreover, the effects of substrate/superstrate's thickness on the MA's tunability are discussed. The insight gained from the generic analysis enabled us to design an optimized tunable MA with relative frequency tuning range as larger as 11.5% while keeping the absorptivity higher than 98.5%. Our results pave a path towards applications with tunable devices, such as selective thermal emitters, sensors, and bolometers. © 2014 Optical Society of America.

Hu W.,University of Electronic Science and Technology of China | Yen G.G.,Oklahoma State University
IEEE Transactions on Evolutionary Computation | Year: 2015

Managing convergence and diversity is essential in the design of multiobjective particle swarm optimization (MOPSO) in search of an accurate and well distributed approximation of the true Pareto-optimal front. Largely due to its fast convergence, particle swarm optimization incurs a rapid loss of diversity during the evolutionary process. Many mechanisms have been proposed in existing MOPSOs in terms of leader selection, archive maintenance, and perturbation to tackle this deficiency. However, few MOPSOs are designed to dynamically adjust the balance in exploration and exploitation according to the feedback information detected from the evolutionary environment. In this paper, a novel method, named parallel cell coordinate system (PCCS), is proposed to assess the evolutionary environment including density, rank, and diversity indicators based on the measurements of parallel cell distance, potential, and distribution entropy, respectively. Based on PCCS, strategies proposed for selecting global best and personal best, maintaining archive, adjusting flight parameters, and perturbing stagnation are integrated into a self-adaptive MOPSO (pccsAMOPSO). The comparative experimental results show that the proposed pccsAMOPSO outperforms the other eight state-of-the-art competitors on ZDT and DTLZ test suites in terms of the chosen performance metrics. An additional experiment for density estimation in MOPSO illustrates that the performance of PCCS is superior to that of adaptive grid and crowding distance in terms of convergence and diversity. © 2014 IEEE.

Gao B.,University of Electronic Science and Technology of China | Bai L.,University of Electronic Science and Technology of China | Woo W.L.,Newcastle University | Tian G.,University of Electronic Science and Technology of China | Tian G.,Newcastle University
Applied Physics Letters | Year: 2014

Analysis of thermography spatial- Transient patterns has considerable potential to enable automatic identification and quantification of detects in non-destructive testing and evaluation. This Letter proposes a non-negative pattern separation model for eddy current pulsed thermography to automatically extract important spatial and time patterns according to the transient thermal sequences without any pro- Training or prior knowledge. In particular, the method is scale-invariant, such that large differences in surface emissivity, hot spots, and cool areas with dynamic range of thermal contrast can be extracted. Finally, an artificial slot in a steel sample with shining, black strip on the surface is tested to validate the proposed method. © 2014 AIP Publishing LLC.

Zhang C.,University of Electronic Science and Technology of China | Yi Z.,Sichuan University
Information Sciences | Year: 2011

This paper proposes a novel PSO algorithm, referred to as SFIPSO (Scale-free fully informed particle swarm optimization). In the proposed algorithm a modified Barabási-Albert (BA) model [4] is used as a self-organizing construction mechanism, in order to adaptively generate the population topology exhibiting scale-free property. The swarm population is divided into two subpopulations: the active particles and the inactive particles. The former fly around the solution space to find the global optima; whereas the latter are iteratively activated by the active particles via attaching to them, according to their own degrees, fitness values, and spatial positions. Therefore, the topology will be gradually generated as the construction process and the optimization process progress synchronously. Moreover, the cognitive effect and the social effect on the variance of a particle's velocity vector are distributed by its "contextual fitness" value, and the social effect is further distributed via a time-varying weighted fully informed mechanism that originated from [27]. It is proved by the results of comparative experiments carried out on eight benchmark test functions that the scale-free population topology construction mechanism and the weighted fully informed learning strategy can provide the swarm population with stronger diversity during the convergent process. As a result, SFIPSO obtained success rate of 100% on all of the eight test functions. Furthermore, SFIPSO also yielded good-quality solutions, especially on multimodal test functions. We further test the network properties of the generated population topology. The results prove that (1) the degree distribution of the topology follows power-law, therefore exhibits scale-free property, and (2) the topology exhibits "disassortative mixing" property, which can be interpreted as an important condition for the reinforcement of population diversity. © 2011 Elsevier Inc. All rights reserved.

Xu P.,University of Electronic Science and Technology of China | Ding Z.,Newcastle University | Dai X.,University of Electronic Science and Technology of China
IEEE Transactions on Information Forensics and Security | Year: 2013

This paper studies the impact of partial encoder cooperation on the secrecy of the multiple access channel (MAC) with an external eavesdropper. In particular, two encoders, connected by two communication links with finite capacities, wish to send secret messages to the common intended decoder in the presence of a passive eavesdropper. The inner and outer bounds on the secrecy capacity are derived for the discrete memoryless channel. The derived inner bound rate region is achievable by combining Willems's coding for the MAC with partially cooperating encoders and Wyner's random binning for the wiretap channel. Then, both the inner and outer bounds are extended to the Gaussian case and the corresponding rate regions are established. Several simple achievable transmission schemes are proposed for the Gaussian channel and the numerical results show that the partial encoder cooperation can increase the achievable rate regions. © 2013 IEEE.

Lu L.,Hangzhou Normal University | Lu L.,University of Fribourg | Lu L.,University of Electronic Science and Technology of China | Medo M.,University of Fribourg | And 10 more authors.
Physics Reports | Year: 2012

The ongoing rapid expansion of the Internet greatly increases the necessity of effective recommender systems for filtering the abundant information. Extensive research for recommender systems is conducted by a broad range of communities including social and computer scientists, physicists, and interdisciplinary researchers. Despite substantial theoretical and practical achievements, unification and comparison of different approaches are lacking, which impedes further advances. In this article, we review recent developments in recommender systems and discuss the major challenges. We compare and evaluate available algorithms and examine their roles in the future developments. In addition to algorithms, physical aspects are described to illustrate macroscopic behavior of recommender systems. Potential impacts and future directions are discussed. We emphasize that recommendation has great scientific depth and combines diverse research fields which makes it interesting for physicists as well as interdisciplinary researchers. © 2012 Elsevier B.V.

Raju S.,Hong Kong University of Science and Technology | Wu R.,University of Electronic Science and Technology of China | Chan M.,Hong Kong University of Science and Technology | Yue C.P.,Hong Kong University of Science and Technology
IEEE Transactions on Power Electronics | Year: 2014

This paper presents a compact model of mutual inductance between two planar inductors, which is essential to design and optimize a wireless power transmission system. The tracks of the planar inductors are modeled as constant current carrying filaments, and the mutual inductance between individual filaments is determined by Neumann's integral. The proposed model is derived by solving Neumann's integral using a series expansion technique. This model can predict the mutual inductance at various axial and lateral displacements. Mutual coupling between planar inductors is computed by a 3-D electromagnetic (EM) solver, and the proposed model shows good agreement with these numerical results. Different types of planar inductors were fabricated on a printed circuit board (PCB) or silicon wafer. Using these inductors, wireless power links were constructed for applications like implantable biomedical devices and contactless battery charging systems. Mutual inductance was measured for each of the cases, and the comparison shows that the proposed model can predict mutual coupling suitably. © 1986-2012 IEEE.

Wu R.,University of Electronic Science and Technology of China | Li W.,University of Electronic Science and Technology of China | Luo H.,University of Electronic Science and Technology of China | Sin J.K.O.,Hong Kong University of Science and Technology | Yue C.P.,Hong Kong University of Science and Technology
IEEE Transactions on Power Electronics | Year: 2014

In this paper, the design of an inductive power link (IPL) for wireless power transfer (WPT) in brain-machine interface (BMI) applications is thoroughly studied. The constraints and requirements of BMI applications are analyzed. By theoretical derivations, the relationships between the IPL performances and its electrical parameters are determined. The design guidelines for the IPL physical parameters are then obtained through experimental characterizations. Experimental results show that with proper IPL design, the efficiency can be improved from the previously reported values of 29.9% and 4.3% to 33.1% and 9.2% for BMI WPT distances of 5 and 12.5 mm, respectively. © 1986-2012 IEEE.

Wang W.-Q.,University of Electronic Science and Technology of China | Wang W.-Q.,Nanjing Southeast University
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2012

Persistent regional monitoring is particularly valuable in remote sensing applications. Inspired by the advantages of near-space vehicles as compared to satellites and airplanes, this paper presents a regional remote sensing approach by near-space vehicle-borne passive bistatic radars. Note that near-space is defined as the altitude region between 20 and 100. km, which is too high up for conventional airplanes but too low for current satellites. We place passive radar receivers inside near-space vehicles which work in conjunction with opportunistic illuminators such as global positioning system (GPS), spaceborne radar, airborne radar or even ground-based radar as the transmitter, to provide a persistent monitoring. The comparative advantages of near-space vehicle as compared to satellite and airplane are investigated. The system models, signal processing algorithm, synchronization processing technique, and the conceptual design examples are presented. Since experimental data are not available for us, numerical simulation results are provided. Although passive radar is not a new concept, the originality of this paper lies in the matched filter reference signal extraction and synchronization processing algorithms. © 2012 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).

Fang J.,University of Electronic Science and Technology of China | Li H.,Stevens Institute of Technology | Chen Z.,University of Electronic Science and Technology of China | Li S.,University of Electronic Science and Technology of China
IEEE Transactions on Signal Processing | Year: 2012

We consider a decentralized detection problem in a power-constrained wireless sensor network (WSN), in which a number of sensor nodes collaborate to detect the presence of a deterministic vector signal. The signal to be detected is assumed known a priori. Each sensor conducts a local linear processing to convert its observations into one or multiple messages. The messages are conveyed to the fusion center (FC) by an uncoded amplify-and-forward scheme, where a global decision is made. Given a total network transmit power constraint, we investigate the optimal linear processing strategy for each sensor. Our study finds that the optimal linear precoder has the form of a matched filter. Depending on the channel characteristics, one or multiple versions of the filtered/compressed message should be reported to the FC. In addition, assuming a fixed total transmit power, we examine how the detection performance behaves with the number of sensors in the network. Analysis shows that increasing the number of sensors can substantially improve the system detection reliability. Finally, decentralized detection with unknown signals is studied and a heuristic precoding design is proposed. Numerical results are conducted to corroborate our theoretical analysis and to illustrate the performance of the proposed algorithm. © 2012 IEEE.

Shen Y.,University of Electronic Science and Technology of China | Fang J.,University of Electronic Science and Technology of China | Li H.,Stevens Institute of Technology
IEEE Signal Processing Letters | Year: 2013

The fact that fewer measurements are needed by log-sum minimization for sparse signal recovery than the L1-minimization has been observed by extensive experiments. Nevertheless, such a benefit brought by the use of the log-sum penalty function has not been rigorously proved. This paper provides a theoretical justification for adopting the log-sum as an alternative sparsity-encouraging function. We prove that minimizing the log-sum penalty function subject to Az = y is able to yield the exact solution, provided that a certain condition is satisfied. Specifically, our analysis suggests that, for a properly chosen regularization parameter, exact reconstruction can be attained when the restricted isometry constant δ3k is smaller than one, which presents a less restrictive isometry condition than that required by the conventional L1-type methods. © 1994-2012 IEEE.

Jiang Z.,University of Electronic Science and Technology of China | Van Dijke M.I.J.,Heriot - Watt University | Sorbie K.S.,Heriot - Watt University | Couples G.D.,Heriot - Watt University
Water Resources Research | Year: 2013

Developing a better understanding of single-/multiphase flow through reservoir rocks largely relies on characterizing and modeling the pore system. For simple homogeneous rock materials, a complete description of the real pore structure can be obtained from the pore network extracted from a rock image at a single resolution, and then an accurate prediction of fluid flow properties can be achieved by using network model. However, for complex rocks (e.g., carbonates, heterogeneous sandstones, deformed rocks), a comprehensive description of the real pore structure may involve several decades of length scales (e.g., from submicron to centimeters), which cannot be captured by a single-resolution image due to the restriction of image size and resolution. Hence, the reconstruction of a single 3-D multiple-scale model of a porous medium is an important step in quantitatively characterizing such heterogeneous rocks and predicting their multiphase flow properties. In this paper, we present a novel methodology for the numerical construction of the multiscale pore structure of a complex rock from a number of CT images/models of a carbonate sample at several length scales. The success of this reconstruction relies heavily on image segmentation, pore network extraction and stochastic network generation, which are provided by our existing software system, referred to as Pore Analysis Tools (PAT). Specifically, the statistical description of pore networks of 3-D rock images at multiple resolutions makes it possible for us to: (a) construct an arbitrary sized network which is equivalent in a specified domain, and (b) integrate multiple networks of different sizes into a single network incorporating all scales. Using multiscale networks of carbonate rocks generated in this manner, two-phase network modeling results are presented to show how the resulting flow properties are dependent on inclusion of information from multiple scales. These outcomes reinforce the importance of capturing both geometry and topology in the hierarchical pore structure for such complex pore systems. The example presented reveals that isolated large-scale (e.g., macro-) pores are mainly connected by small-scale (e.g., micro-) pores, which in turn determines the combined effective petrophysical properties (capillary pressure, absolute and relative permeability). It is also demonstrated that multi- (three) scale networks reveal the effects of the interacting multiscale pore systems (e.g., micropores, macropores, and vugs) on bulk flow properties in terms of two-phase flow properties. Key Points To capture the multi-scale heterogeneity of complex porous media. To illustrate the effects of multi-scale pore systems on flow properties. To highlight the importance of equivalent stochastic network in flow simulation ©2013. American Geophysical Union. All Rights Reserved.

Zhang C.,University of Electronic Science and Technology of China | Yi Z.,Sichuan University
Neurocomputing | Year: 2010

Self-nonself discrimination has long been the fundamental model of modern theoretical immunology. Based on this principle, some effective and efficient artificial immune algorithms have been proposed and applied to a wide range of engineering applications. Over the last few years, a new model called "danger theory" has been developed to challenge the classical self-nonself model. In this paper, a novel immune algorithm inspired by danger theory is proposed for solving on-line supervised two-class classification problems. The general framework of the proposed algorithm is described, and several essential issues related to the learning process are also discussed. Experiments based on both artificial data sets and real-world problems are carried out to visualize the learning process, as well as to evaluate the classification performance of our method. It is shown empirically by the experimental results that the proposed algorithm exhibits competitive classification accuracy and generalization capability. © 2010 Elsevier B.V. All rights reserved.

Das K.,Harish Chandra Research Institute | Li T.,CAS Institute of Theoretical Physics | Li T.,University of Electronic Science and Technology of China | Nandi S.,Oklahoma State University | Rai S.K.,Harish Chandra Research Institute
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

The resonant excesses around 2 TeV reported by the ATLAS Collaboration can be explained in the left-right model, and the tight constraints from lepton plus missing energy searches can be evaded if the SU(2)R gauge symmetry is leptophobic. We, for the first time, propose an anomaly- free leptophobic left-right model with gauge symmetry SU(3)C×SU(2)L×SU(2)R×U(1)X, where the SM leptons are singlets under SU(2)R. The gauge anomalies are cancelled by introducing extra vectorlike quarks. The mass of the Z′ gauge boson, which cannot be leptophobic, is assumed to be around or above 2.5 TeV so that the constraint on the dilepton final state can be avoided. Moreover, we find that the W′→WZ channel cannot explain the ATLAS diboson excess due to the tension with the constraint on the W′→jj decay mode. We solve this problem by considering the mixings between the SM quarks and vectorlike quarks. We show explicitly that the ATLAS diboson excess can be explained in the viable parameter space of our model, which is consistent with all the current experimental constraints. © 2016 American Physical Society.

Hu W.,University of Electronic Science and Technology of China | Yen G.G.,Oklahoma State University
2013 IEEE Congress on Evolutionary Computation, CEC 2013 | Year: 2013

Leader selection and archive maintenance are the two key issues, which have an important impact on the performance of the obtained approximate Pareto front, to be tackled when extending Single-Objective Particle Swarm Optimization to Multi-Objective Particle Swarm Optimization (MOPSO). In this paper, a new method of density estimation is proposed for selecting leaders and maintaining archive in MOPSO. The density of a nondominated solution in archive is calculated according to the Parallel Cell Distance after the archive is mapped from Cartesian Coordinate System into Parallel Cell Coordinate System. A new MOPSO is proposed based on this method of density estimation for selecting leaders and maintaining archive to improve the performance of convergence and diversity. The experimental results show that the proposed algorithm is significantly superior to the five chosen state-of-the-art MOPSOs on 12 test problems in term of hypervolume performance indicator. © 2013 IEEE.

Ren P.-G.,Xi'an University of Technology | Yan D.-X.,Sichuan University | Ji X.,University of Sichuan | Chen T.,University of Electronic Science and Technology of China | Li Z.-M.,Sichuan University
Nanotechnology | Year: 2011

Graphene oxide (GO) was successfully prepared by a modified Hummer's method. The reduction effect and mechanism of the as-prepared GO reduced with hydrazine hydrate at different temperatures and time were characterized by x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), x-ray diffractions (XRD), Raman spectroscopy and thermo-gravimetric analysis (TGA). The results showed that the reduction effect of GO mainly depended on treatment temperature instead of treatment time. Desirable reduction of GO can only be obtained at high treatment temperature. Reduced at 95 °C for 3 h, the C/O atomic ratio of GO increased from 3.1 to 15.1, which was impossible to obtain at low temperatures, such as 80, 60 or 15 °C, even for longer reduction time. XPS, 13C NMR and FTIR results show that most of the epoxide groups bonded to graphite during the oxidation were removed from GO and form the sp2 structure after being reduced by hydrazine hydrate at high temperature (>60 °C), leading to the electric conductivity of GO increasing from 1.5 × 10-6 to 5 S cm -1, while the hydroxyls on the surface of GO were not removed by hydrazine hydrate even at high temperature. Additionally, the FTIR, XRD and Raman spectrum indicate that the GO reduced by hydrazine hydrate can not be entirely restored to the pristine graphite structures. XPS and FTIR data also suggest that carbonyl and carboxyl groups can be reduced by hydrazine hydrate and possibly form hydrazone, but not a C=C structure. © 2011 IOP Publishing Ltd Printed in the UK & the USA.

Yao G.-G.,Shaanxi Normal University | Yao G.-G.,University of Posts and Telecommunications | Liu P.,Shaanxi Normal University | Zhang H.-W.,University of Electronic Science and Technology of China
Journal of the American Ceramic Society | Year: 2013

Using a conventional solid-state reaction Ca5A 4(VO4)6 (A2+ = Mg, Zn) ceramics were prepared and their microwave dielectric properties were investigated for the first time. X-ray diffraction revealed the formation of pure-phase ceramics with a cubic garnet structure for both samples. Two promising ceramics Ca 5Zn4(VO4)6 and Ca5Mg 4(VO4)6 sintered at 725°C and 800°C were found to possess good microwave dielectric properties: εr = 11.7 and 9.2, Q × f = 49 400 GHz (at 9.7 GHz) and 53 300 GHz (at 10.6 GHz), and τf = -83 and -50 ppm/°C, respectively. © 2013 The American Ceramic Society.

Lin P.,University of Electronic Science and Technology of China | Jia Y.,Beihang University
IET Control Theory and Applications | Year: 2010

This study is concerned with consensus problems for a class of multi-agent systems with second-order dynamics. Some dynamic neighbour-based rules are adopted for the agents with the consideration of parameter uncertainties and external disturbances. Sufficient conditions are derived to make all agents asymptotically reach consensus while satisfying desired H∞ performance. Finally, numerical simulations are provided to show the effectiveness of our theoretical results. © 2010 The Institution of Engineering and Technology.

Lu Q.,Basque Center for Applied Mathematics | Lu Q.,University of Electronic Science and Technology of China
Inverse Problems | Year: 2012

In this paper, we establish a global Carleman estimate for stochastic parabolic equations. Based on this estimate, we study two inverse problems for stochastic parabolic equations. One is concerned with a determination problem of the history of a stochastic heat process through the observation at the final time T for which we obtain a conditional stability estimate. The other is an inverse source problem with observation on the lateral boundary. We derive the uniqueness of the source. © 2012 IOP Publishing Ltd.

Qiu T.,Nanchang Hangkong University | Zhang Z.-K.,Hangzhou Normal University | Zhang Z.-K.,University of Electronic Science and Technology of China | Zhang Z.-K.,Beijing Computational Science Research Center | Chen G.,Nanchang Hangkong University
PLoS ONE | Year: 2013

Finding a universal description of the algorithm optimization is one of the key challenges in personalized recommendation. In this article, for the first time, we introduce a scaling-based algorithm (SCL) independent of recommendation list length based on a hybrid algorithm of heat conduction and mass diffusion, by finding out the scaling function for the tunable parameter and object average degree. The optimal value of the tunable parameter can be abstracted from the scaling function, which is heterogeneous for the individual object. Experimental results obtained from three real datasets, Netflix, MovieLens and RYM, show that the SCL is highly accurate in recommendation. More importantly, compared with a number of excellent algorithms, including the mass diffusion method, the original hybrid method, and even an improved version of the hybrid method, the SCL algorithm remarkably promotes the personalized recommendation in three other aspects: solving the accuracy-diversity dilemma, presenting a high novelty, and solving the key challenge of cold start problem. © 2013 Qiu et al.

Liu S.,University of Electronic Science and Technology of China | Xiong L.,Paramount science | He C.,Chengdu Yanbai Technology Co.
Journal of Power Sources | Year: 2014

Lithium ion batteries with lithium nickel cobalt manganese oxide (NCM) cathode were characterized by extensive cycling (>2000 cycles), discharge rate test, hybrid pulse power characterization test (HPPC), and electrochemical impedance spectroscopy (EIS). The crystal structure, morphology and particle size of cathode materials were characterized by X-ray diffraction and scanning electron microscopy (SEM). It was demonstrated that the rate performance and cycle life of battery are closely related to the cathode material composition and electrode design. With proper selection of cathode composition and electrode design, the lithium ion battery cell achieved close to 3500 cycles with 85% capacity retention at 1C current. © 2014 Elsevier B.V. All rights reserved.

Gou J.,University of Electronic Science and Technology of China | Yi Z.,Sichuan University
Computer Journal | Year: 2013

In this article, we develop a linear supervised subspace learning method called locality-based discriminant neighborhood embedding (LDNE), which can take advantage of the underlying submanifold-based structures of the data for classification. Our LDNE method can simultaneously consider both 'locality' of locality preserving projection (LPP) and 'discrimination' of discriminant neighborhood embedding (DNE) in manifold learning. It can find an embedding that not only preserves local information to explore the intrinsic submanifold structure of data from the same class, but also enhances the discrimination among submanifolds from different classes. To investigate the performance of LDNE, we compare it with the state-of-the-art dimensionality reduction techniques such as LPP and DNE on publicly available datasets. Experimental results show that our LDNE can be an effective and robust method for classification. © 2013 The Author.

Lin P.,Beihang University | Lin P.,University of Electronic Science and Technology of China | Jia Y.,Beihang University
IEEE Transactions on Automatic Control | Year: 2010

This technical note investigates consensus problems of a class of second-order continuous-time multi-agent systems with time-delay and jointly-connected topologies. We first introduce a neighbor-based linear protocol with time-delay. Then we derive a sufficient condition in terms of linear matrix inequalities (LMIs) for average consensus of the system. Furthermore, we discuss the case where the time-delay affects only the information that is being transmitted and show that consensus can be reached with arbitrary bounded time-delay. Finally, simulation results are provided to demonstrate the effectiveness of our theoretical results. © 2010 IEEE.

Lin P.,University of Electronic Science and Technology of China | Jia Y.,Beihang University
Systems and Control Letters | Year: 2010

This paper investigates collective rotating motions of second-order multi-agent systems. We first consider rotating consensus problems. Using local relative information, we propose a protocol and give a necessary and sufficient condition for rotating consensus of the system. Then, we consider rotating formation control problems. With the help of Lyapunov theory for complex systems, we propose rotating formation protocols and give sufficient conditions to make all agents move with a specific structure in a circular channel. Finally, simulation results are provided to demonstrate the effectiveness of our theoretical results. © 2010 Elsevier B.V. All rights reserved.

Cheng Y.J.,University of Electronic Science and Technology of China | Hong W.,Nanjing Southeast University | Wu K.,Ecole Polytechnique de Montréal
IEEE Transactions on Antennas and Propagation | Year: 2012

A planar W-band monopulse antenna array is designed based on the substrate integrated waveguide (SIW) technology. The sum-difference comparator, 16-way divider and 32 × 32 slot array antenna are all integrated on a single dielectric substrate in the compact layout through the low-cost PCB process. Such a substrate integrated monopulse array is able to operate over 93 ∼ 96 GHz with narrow-beam and high-gain. The maximal gain is measured to be 25.8 dBi, while the maximal null-depth is measured to be - 43.7 dB. This SIW monopulse antenna not only has advantages of low-cost, light, easy-fabrication, etc., but also has good performance validated by measurements. It presents an excellent candidate for W-band directional-finding systems. © 2006 IEEE.

Wang N.,University of Electronic Science and Technology of China | Ding Z.,Northumbria University | Dai X.,University of Electronic Science and Technology of China | Vasilakos A.V.,University of Western Macedonia
IEEE Transactions on Vehicular Technology | Year: 2011

In this paper, we first study the design of network coding for the generalized multiple-input-multiple-output (MIMO) Y channels, where K users wish to exchange information with each other within two time slots. Precoding at each user and the relay is carefully constructed to ensure that the signals from the same user pair are grouped together and that cross-pair interference can be canceled. In addition, a simple mapping function is proposed to ensure low-complexity detection at the relay. Exact expressions of symbol error rate (SER) are then developed to establish the explicit relationship between the diversity gain and the number of node antennas. Monte Carlo simulation is also provided to demonstrate the performance of the proposed scheme. © 2010 IEEE.

Mu B.,University of Electronic Science and Technology of China | Mu B.,Sichuan University | Wang P.,Sichuan University | Yang H.,Sichuan University | Yang H.,CAS Institute of Theoretical Physics
Advances in High Energy Physics | Year: 2015

We investigate effects of the minimal length on quantum tunnelling from spherically symmetric black holes using the Hamilton-Jacobi method incorporating the minimal length. We first derive the deformed Hamilton-Jacobi equations for scalars and fermions, both of which have the same expressions. The minimal length correction to the Hawking temperature is found to depend on the black hole's mass and the mass and angular momentum of emitted particles. Finally, we calculate a Schwarzschild black hole's luminosity and find the black hole evaporates to zero mass in infinite time. © 2015 Benrong Mu et al.

Cui G.,Stevens Institute of Technology | Cui G.,University of Electronic Science and Technology of China | Li H.,Stevens Institute of Technology | Rangaswamy M.,Air Force Research Lab
IEEE Transactions on Signal Processing | Year: 2014

We consider the problem of waveform design for Multiple-Input Multiple-Output (MIMO) radar in the presence of signal-dependent interference embedded in white Gaussian disturbance. We present two sequential optimization procedures to maximize the Signal to Interference plus Noise Ratio (SINR), accounting for a constant modulus constraint as well as a similarity constraint involving a known radar waveform with some desired properties (e.g., in terms of pulse compression and ambiguity). The presented sequential optimization algorithms, based on a relaxation method, yield solutions with good accuracy. Their computational complexity is linear in the number of iterations and trials in the randomized procedure and polynomial in the receive filter length. Finally, we evaluate the proposed techniques, by considering their SINR performance, beam pattern as well as pulse compression property, via numerical simulations. © 1991-2012 IEEE.

Zhu W.,Monash University | Huang Y.,University of Electronic Science and Technology of China | Rukhlenko I.D.,Monash University | Wen G.,University of Electronic Science and Technology of China | Premaratne M.,Monash University
Optics Express | Year: 2012

Metamaterials attain their behavior due to resonant interactions among their subwavelength components and thus show specific designer features only in a very narrow frequency band. There is no simple way to dynamically increase the operating bandwidth of a narrowband metamaterial, but it may be possible to change its central frequency, shifting the spectral response to a new frequency range. In this paper, we propose and experimentally demonstrate a metamaterial absorber that can shift its central operating frequency by using mechanical means. The shift is achieved by varying the gap between the metamaterial and an auxiliary dielectric slab parallel to its surface. We also show that it is possible to create multiple absorption peaks by adjusting the size and/or shape of the dielectric slab, and to shift them by moving the slab relative to the metamaterial. Specifically, using numerical simulations we design a microwave metamaterial absorber and experimentally demonstrate that its central frequency can be set anywhere in a 1.6 GHz frequency range. The proposed configuration is simple and easy to make, and may be readily extended to THz frequencies. © 2012 Optical Society of America.

Jiang T.,University of Electronic Science and Technology of China | Jiang T.,University of Massachusetts Dartmouth | Wang H.,University of Massachusetts Dartmouth | Vasilakos A.V.,University of Western Macedonia
IEEE Journal on Selected Areas in Communications | Year: 2012

With the fast growing of multimedia communication applications, cognitive radio networks have gained the popularity as they can provide high wireless bandwidth and support quality-driven wireless multimedia services. In multimedia applications such as video conferences over the cognitive radio, the Quality of Experience (QoE) that directly measures the satisfaction of the end users cannot be easily realized due to the limited spectrum resources. The opportunistic spectrum access cognitive radio (CR) is an efficient technology to address this issue. However, the unstable channels allocated to the multimedia secondary users (SUs) can be re-occupied by the primary users (PUs) at any time, which makes the CR difficult to meet the QoE requirements. Therefore, it is important to study how to allocate frequency or spectrum resources to SUs according to their QoE requirements. This paper proposes a novel QoE-driven channel allocation scheme for SUs and cognitive radio networks (CRN) base station (BS). The historical QoE data under different primary channels (PCs) are collected by the SUs and delivered to a Cognitive Radio Base Station (CRBS). The CRBS will allocate available channel resources to the SUs based on their QoE expectations and maintain a priority service queue. The modified ON/OFF models of PCs and service queue models of SUs are jointly investigated for this channel allocation scheme. The performance of multimedia transmission of images and H.264 videos under our CR channel allocation scheme is studied, the results show that the proposed channel allocation approach can significantly improve the QoE of the priority-based SUs over the cognitive radio networks. © 1983-2012 IEEE.

Wu K.,Ecole Polytechnique de Montréal | Cheng Y.J.,University of Electronic Science and Technology of China | Djerafi T.,Ecole Polytechnique de Montréal | Hong W.,Nanjing Southeast University
Proceedings of the IEEE | Year: 2012

Significant advances in the development of millimeter-wave and terahertz (30-10000 GHz) technologies have been made to cope with the increasing interest in this still not fully explored electromagnetic spectrum. The nature of electromagnetic waves over this frequency range is well suited for the development of high-resolution imaging applications, molecular-sensitive spectroscopic devices, and ultrabroadband wireless communications. In this paper, millimeter-wave and terahertz antenna technologies are overviewed including the conventional and nonconventional planar/nonplanar antenna structures based on different platforms. As a promising technological platform, substrate-integrated circuits (SICs) attract more and more attention. Various substrate-integrated waveguide (SIW) schemes and other synthesized guide techniques have been widely employed in the design of antennas and arrays. Different types of substrate-integrated antennas and beamforming networks are discussed with respect to theoretical and experimental results in connection with electrical and mechanical performances. © 2012 IEEE.

Gao Q.,Huazhong University of Science and Technology | Gong Y.,Huazhong University of Science and Technology | Li T.,CAS Institute of Theoretical Physics | Li T.,University of Electronic Science and Technology of China
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

To reconcile the BICEP2 measurement on the tensor-to-scalar ratio r with Planck constraint, a large negative running of scalar spectral index ns is needed. So the inflationary observable such as ns should be expanded at least to the second-order slow-roll parameters for single-field inflationary models. The large value of r and the Lyth bound indicate that it is impossible to obtain the sub-Planckian excursion for the inflaton. However, we derive an absolutely minimal bound Δφ/MPl>r/2 on the inflaton excursion for single-field inflationary models, which can be applied to non-slow-roll inflationary models as well. This bound excludes the possibility of the small-field inflation with Δφ<0.1MPl if the BICEP2 result on r stands, and it opens the window of sub-Planckian excursion with Δφ

Liu Y.,Xiamen University | Liu Q.H.,Duke University | Nie Z.,University of Electronic Science and Technology of China
IEEE Transactions on Antennas and Propagation | Year: 2014

Previously, the matrix pencil method (MPM) and the forward-backward MPM (FBMPM) were used to effectively reduce the number of antenna elements in the single-pattern linear arrays. This work extends the MPM and FBMPM-based synthesis methods to the synthesis of multiple-pattern linear arrays with a smaller number of elements. The extended MPM (resp., the extended FBMPM) method organizes all the multiple pattern data into a composite Hankel (resp., composite Hankel-Toeplitz) matrix from which the minimum number of elements and the common poles corresponding to element positions can be obtained with similar processing used in the original MPM or FBMPM synthesis method. In particular, the extended FBMPM inherits the advantage of the original FBMPM that a useful restriction is put on the distribution of poles, which makes the element positions obtained much more accurate and robust. Numerical experiments are conducted to validate the effectiveness and robustness of the proposed methods. For the tested cases, the element saving is about 20% ~ 25% for reconfigurable shaped patterns, and can be even more for electrically large linear arrays with scanned pencil-beams. © 1963-2012 IEEE.

Li T.,CAS Institute of Theoretical Physics | Li T.,University of Electronic Science and Technology of China | Li Z.,Texas A&M University | Nanopoulos D.V.,Texas A&M University | And 2 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We show that the quadratic inflation can be realized by the phase of a complex field with helicoid potential. Remarkably, this helicoid potential can be simply realized in minimal supergravity. The global U(1) symmetry of the Kähler potential introduces a flat direction and evades the η problem automatically. So such inflation is technically natural. The phase excursion is super-Planckian as required by the Lyth bound, while the norm of the complex field can be suppressed in the sub-Planckian region. This model resolves the ultraviolet sensitive problem of the large field inflation; besides, it also provides a new type of monodromy inflation in supersymmetric field theory with consistent field stabilization. © 2015 American Physical Society.

Li T.,CAS Institute of Theoretical Physics | Li T.,University of Electronic Science and Technology of China | Raza S.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Considering the generalized minimal supergravity model in the minimal supersymmetric Standard Model, we study the electroweak supersymmetry, in which the squarks and/or gluino are heavy around a few TeVs while the sleptons, sneutrinos, bino, winos, and/or Higgsinos are light within 1 TeV. We resolve the (g-2)μ/2 discrepancy for the muon anomalous magnetic moment in the Standard Model successfully and identify a parameter space in which such solutions also have the electroweak fine-tuning measures ΔEW 16.5 (6%) and ΔEW 25 (4%) without and with the Wilkinson Microwave Anisotropy Probe (WMAP) bounds, respectively. We find that the allowed mass ranges, which are consistent within 3σ of the g-2 discrepancy, for the lightest neutralino, charginos, stau, stau neutrinos, and first two-family sleptons are [44, 390], [100, 700], [100, 700], [52, 800], and [150, 800] GeV, respectively. Moreover, our solutions satisfy the latest bounds reported by the ATLAS and CMS collaborations on electroweakinos and sleptons. The colored sparticles such as light stop, gluinos, and the first the first two generations of squark masses have been found in the mass ranges of [500, 3000], [1300, 4300], and [1800, 4200] GeV, respectively. To obtain the observed dark matter relic density for the lightest supersymmetric particle (LSP) neutralino, we have the bino-wino, LSP neutralino-stau, and LSP neutralino-tau sneutrinos coannihilation scenarios and the resonance solutions such as the A pole, Higgs pole, and Z pole. We identify the Higgsino-like LSP neutralino and display its spin-independent and spin-dependent cross sections with nucleons. We present ten benchmark points that can be tested at the up coming collider searches as well. © 2015 American Physical Society.

Cheng T.,CAS Institute of Theoretical Physics | Li T.,CAS Institute of Theoretical Physics | Li T.,University of Electronic Science and Technology of China | Li T.,Texas A&M University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

To explain all the available experimental results, we have proposed the electroweak supersymmetry (EWSUSY) previously, where the squarks and/or gluino are heavy around a few TeVs while the sleptons, sneutrinos, bino, winos, and/or Higgsinos are light within 1 TeV. In the next to minimal supersymmetric Standard Model, we perform the systematic χ2 analyses on parameter space scan for three EWSUSY scenarios: (I) R-parity conservation and one dark matter candidate, (II) R-parity conservation and multicomponent dark matter, (III) R-parity violation. We obtain the minimal χ2/(degree of freedom) of 10.2/15, 9.6/14, and 9.2/14 respectively for scenarios I, II, and III. Considering the constraints from the LHC neutralino/chargino and slepton searches, we find that the majority of viable parameter space preferred by the muon anomalous magnetic moment has been excluded except for the parameter space with moderate to large tanâ¡β(8). Especially, the most favorable parameter space has relatively large tanâ¡β, moderate λ, small μeff, heavy squarks/gluino, and the second lightest CP-even neutral Higgs boson with mass around 125 GeV. In addition, if the left-handed smuon is nearly degenerate with or heavier than wino, there is no definite bound on wino mass. Otherwise, the wino with mass up to ∼450 GeV has been excluded. Furthermore, we present several benchmark points for scenarios I and II, and briefly discuss the prospects of the EWSUSY searches at the 14 TeV LHC and ILC. © 2013 American Physical Society.

Cheng H.,University of Electronic Science and Technology of China | Liu Z.,Microsoft | Yang L.,University of Electronic Science and Technology of China | Chen X.,Wayne State University
Signal Processing | Year: 2013

Sparse representation and learning has been widely used in computational intelligence, machine learning, computer vision and pattern recognition, etc. Mathematically, solving sparse representation and learning involves seeking the sparsest linear combination of basis functions from an overcomplete dictionary. A rational behind this is the sparse connectivity between nodes in human brain. This paper presents a survey of some recent work on sparse representation, learning and modeling with emphasis on visual recognition. It covers both the theory and application aspects. We first review the sparse representation and learning theory including general sparse representation, structured sparse representation, high-dimensional nonlinear learning, Bayesian compressed sensing, sparse subspace learning, non-negative sparse representation, robust sparse representation, and efficient sparse representation. We then introduce the applications of sparse theory to various visual recognition tasks, including feature representation and selection, dictionary learning, Sparsity Induced Similarity (SIS) measures, sparse coding based classification frameworks, and sparsity-related topics. © 2012 Elsevier B.V.

Gao X.,CAS Institute of Theoretical Physics | Gao X.,Virginia Polytechnic Institute and State University | Li T.,CAS Institute of Theoretical Physics | Li T.,University of Electronic Science and Technology of China | Shukla P.,University of Turin
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

In the lights of current BICEP2 observations accompanied with the PLANCK satellite results, it has been observed that the simple single field chaotic inflationary models provide a good agreement with their spectral index ns and large tensor-to-scalar ratio r (0.15

Fang J.,University of Electronic Science and Technology of China | Wen C.,University of North Texas | Pavur R.,University of North Texas
Cyberpsychology, Behavior, and Social Networking | Year: 2012

Liu J.,University of California at Los Angeles | Li L.,University of California at Los Angeles | Li L.,University of Electronic Science and Technology of China | Pei Q.,University of California at Los Angeles
Macromolecules | Year: 2011

We demonstrate that conjugated polymers are able to efficiently host blue and white electrophosphorescence if the conjugated polymer has both high triplet energy level (ET) and high-lying HOMO energy level. A novel conjugated polymer host (PmPTPA) is developed by attaching triphenylamine unit to poly(m-phenylene) backbone. The poly(m-phenylene) backbone endows PmPTPA an ET as high as 2.65 eV, which is sufficiently high to prevent triplet energy back transfer. The tethering triphenylamine unit leads to the HOMO energy level of -5.35 eV for PmPTPA and facilitates hole injection. As the result, blue phosphorescent polymer light-emitting diodes (PPLEDs) based on PmPTPA exhibit the luminance efficiency of 17.9 cd/A and external quantum efficiency of 9.3%. White PPLEDs with blue, green and red phosphorescent dopants dispersed in PmPTPA show the luminance efficiency of 22.1 cd/A and external quantum efficiency of 10.6%. For both the blue and white PPLEDs based on the conjugated polymer host PmPTPA, the EL performance are fairly comparable to those of the state-of-the-art nonconjugated polymer host, poly(vinyl-carbazole) (PVK). These results indicate that conjugated polymers are suitable host materials for PPLEDs with all emission colors. © 2011 American Chemical Society.

Chen G.,Advanced Signal Processing Group | Tian Z.,Advanced Signal Processing Group | Gong Y.,Advanced Signal Processing Group | Chen Z.,University of Electronic Science and Technology of China | Chambers J.A.,Advanced Signal Processing Group
IEEE Transactions on Information Forensics and Security | Year: 2014

This paper considers the security of transmission in buffer-aided decode-and-forward cooperative wireless networks. An eavesdropper which can intercept the data transmission from both the source and relay nodes is considered to threaten the security of transmission. Finite size data buffers are assumed to be available at every relay in order to avoid having to select concurrently the best source-to-relay and relay-to-destination links. A new max-ratio relay selection policy is proposed to optimize the secrecy transmission by considering all the possible source-to-relay and relay-to-destination links and selecting the relay having the link which maximizes the signal to eavesdropper channel gain ratio. Two cases are considered in terms of knowledge of the eavesdropper channel strengths: exact and average gains, respectively. Closed-form expressions for the secrecy outage probability for both cases are obtained, which are verified by simulations. The proposed max-ratio relay selection scheme is shown to outperform one based on a max-min-ratio relay scheme. © 2014 IEEE.

Dutta B.,Texas A&M University | Gao Y.,Texas A&M University | Ghosh T.,Texas A&M University | Gogoladze I.,University of Delaware | And 2 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

We consider the diphoton resonance at the 13 TeV LHC in a consistent model with new scalars and vector-like fermions added to the Standard Model, which can be constructed from orbifold grand unified theories and string models. The gauge coupling unification can be achieved, neutrino masses can be generated radiatively, and the electroweak vacuum stability problem can be solved. To explain the diphoton resonance, we study a spin-0 particle, and discuss various associated final states. We also constrain the couplings and number of the introduced heavy multiplets for the new resonance's width at 5 or 40 GeV. © 2016 American Physical Society.

Yang T.,University of Electronic Science and Technology of China | Chi P.-L.,University of California at Los Angeles | Itoh T.,University of California at Los Angeles
IEEE Transactions on Microwave Theory and Techniques | Year: 2011

Novel and compact composite right/left-handed (CRLH) quarter-wave type resonators are proposed in this paper. The resonator can resonate at the frequency where the electrical length is phase-leading or negative, which results in a smaller size as compared to the conventional phase-delayed microstrip-line resonator. Furthermore, it is only half the size of the CRLH half-wave resonator resonating at the same frequency. In addition, the proposed resonator is capable of engineering the multiresonances very close to each other, which makes it suitable to implement the miniaturized multiband microwave components such as diplexers and triplexers. A very compact diplexer and a very compact triplexer are proposed based on the proposed CRLH quarter-wave resonators in this paper and both of them have demonstrated very good performance. Specifically, compared to the referenced works based on the conventional microstrip resonators, the proposed diplexer and triplexer are 50% and 76% smaller than their microstrip counterparts, respectively. © 2011 IEEE.

Chong H.-F.,Institute for Infocomm Research | Liang Y.-C.,University of Electronic Science and Technology of China
IEEE Transactions on Information Theory | Year: 2016

Zeng K.,University of Electronic Science and Technology of China | Pawelczak P.,University of California at Los Angeles | Cabric D.,University of California at Los Angeles
IEEE Communications Letters | Year: 2010

Existing cooperative spectrum sensing (CSS) schemes are typically vulnerable to attacks where misbehaved cognitive radios (CRs) falsify sensing data. To ensure the robustness of spectrum sensing, this letter presents a secure CSS scheme by introducing a reputation-based mechanism to identify misbehaviors and mitigate their harmful effect on sensing performance. Encouraged by the fact that such secure CSS is sensitive to the correctness of reputations, we further present a trusted node assistance scheme. This scheme starts with reliable CRs. Sensing information from other CRs are incorporated into cooperative sensing only when their reputation is verified, which increases robustness of cooperative sensing. Simulations verify the effectiveness of the proposed schemes. © 2010 IEEE.

Fu Y.,University of Electronic Science and Technology of China | Fu Y.,CAS Chengdu Institute of Optics and Electronics | Zhou X.,University of Electronic Science and Technology of China
Plasmonics | Year: 2010

Four types of plasmonic lenses for the purpose of superfocusing designed on the bases of approximate negative refractive index concept, subwavelength metallic structures, waveguide mode were introduced, and curved chains of nanoparticles, respectively, were introduced. Imaging mechanism, fabrication, and characterization issues were presented. Theoretical analyses of the illumination with different polarization states on focusing performance of the plasmonic lenses were given also. In addition, a hybrid Au-Ag plasmonic lens with chirped slits for the purpose of avoiding oxidation of Ag film was presented. © 2010 Springer Science+Business Media, LLC.

Qi Y.,University of Minnesota | Zhang Y.,University of Minnesota | Zhang Y.,University of Rochester | Zhang F.,University of Minnesota | And 6 more authors.
Genome Research | Year: 2013

Improved methods for engineering sequence-specific nucleases, including zinc finger nucleases (ZFNs) and TAL effector nucleases (TALENs), have made it possible to precisely modify plant genomes. However, the success of genome modification is largely dependent on the intrinsic activity of the engineered nucleases. In this study, we sought to enhance ZFNmediated targeted mutagenesis and gene targeting (GT) in Arabidopsis by manipulating DNA repair pathways. Using a ZFN that creates a double-strand break (DSB) at the endogenous ADH1 locus, we analyzed repair outcomes in the absence of DNA repair proteins such as KU70 and LIG4 (both involved in classic nonhomologous end-joining, NHEJ) and SMC6B (involved in sister-chromatid-based homologous recombination, HR). We achieved a fivefold to 16-fold enhancement in HR-based GT in a ku70 mutant and a threefold to fourfold enhancement in GT in the lig4 mutant. Although the NHEJ mutagenesis frequency was not significantly changed in ku70 or lig4, DNA repair was shifted to microhomology-dependent alternative NHEJ. As a result, mutations in both ku70 and lig4 were predominantly large deletions, which facilitates easy screening for mutations by PCR. Interestingly, NHEJ mutagenesis and GT at the ADH1 locus were enhanced by sixfold to eightfold and threefold to fourfold, respectively, in a smc6b mutant. The increase in NHEJ-mediated mutagenesis by loss of SMC6B was further confirmed using ZFNs that target two other Arabidopsis genes, namely, TT4 and MPK8. Considering that components of DNA repair pathways are highly conserved across species, mutations in DNA repair genes likely provide a universal strategy for harnessing repair pathways to achieve desired targeted genome modifications. © 2013, Published by Cold Spring Harbor Laboratory Press.

Zeng Y.,Institute for Infocomm Research | Liang Y.-C.,Institute for Infocomm Research | Liang Y.-C.,University of Electronic Science and Technology of China | Pham T.-H.,Institute for Infocomm Research
IEEE Journal on Selected Areas in Communications | Year: 2013

Orthogonal frequency division multiplex (OFDM) has been widely used in various wireless communications systems. Thus the detection of OFDM signals is of significant importance in cognitive radio and other spectrum sharing systems. A common feature of OFDM in many popular standards is that some pilot subcarriers repeat periodically after certain OFDM blocks. In this paper, sensing methods for OFDM signals are proposed by using such repetition structure of the pilots. Firstly, special properties for the auto-correlation (AC) of the received signals are identified, from which the optimal likelihood ratio test (LRT) is derived. However, this method requires the knowledge of channel information, carrier frequency offset (CFO) and noise power. To make the LRT method practical, we then propose an approximated LRT (ALRT) method that does not rely on the channel information and noise power, thus the CFO is the only remaining obstacle to the ALRT. To handle the problem, we propose a method to estimate the composite CFO and compensate its effect in the AC using multiple taps of ACs of the received signals. Computer simulations have shown that the proposed sensing methods are robust to frequency offset, noise power uncertainty, time delay uncertainty, and frequency selectiveness of the channel. © 1983-2012 IEEE.

Zhang L.,Institute for Infocomm Research | Zhang R.,Institute for Infocomm Research | Liang Y.-C.,Institute for Infocomm Research | Liang Y.-C.,University of Electronic Science and Technology of China | And 2 more authors.
IEEE Transactions on Information Theory | Year: 2012

Owing to the special structure of the Gaussian multiple-input multiple-output (MIMO) broadcast channel (BC), the associated capacity region computation and beamforming optimization problems are typically non-convex, and thus cannot be solved directly. One feasible approach is to consider the respective dual multiple-access channel (MAC) problems, which are easier to deal with due to their convexity properties. The conventional BC-MAC duality has been established via BC-MAC signal transformation, and is applicable only for the case in which the MIMO BC is subject to a single transmit sum-power constraint. An alternative approach is based on minimax duality, which can be applied to the case of the sum-power constraint or per-antenna power constraint. In this paper, the conventional BC-MAC duality is extended to the general linear transmit covariance constraint (LTCC) case, which includes sum-power and per-antenna power constraints as special cases. The obtained general BC-MAC duality is applied to solve the capacity region computation for the MIMO BC and beamforming optimization for the multiple-input single-output (MISO) BC, respectively, with multiple LTCCs. The relationship between this new general BC-MAC duality and the minimax duality is also discussed, and it is shown that the general BC-MAC duality leads to simpler problem formulations. Moreover, the general BC-MAC duality is extended to deal with the case of nonlinear transmit covariance constraints in the MIMO BC. © 2006 IEEE.

Tamura M.,Panasonic | Yang T.,University of Electronic Science and Technology of China | Itoh T.,University of California at Los Angeles
IEEE Transactions on Microwave Theory and Techniques | Year: 2011

In this paper, two design approaches are presented for realizing very compact and low-profile unbalanced-balanced filters with special configuration called hybrid resonators. One of the design concepts for the unbalanced-balanced filter is based on the folded hybrid resonators. This filter consists of two hybrid resonators, which are folded face to face symmetrically. The capacitance between two resonators is generated by folding the resonators. This approach makes design of compact and low-profile filters possible. The other design concept for the unbalanced-balanced filter consists of resonators that have capacitive and inductive inverters. The feature of this filter is that phase-lag is expressed by inductive coupling. This filter also achieves very low profile and compact size. The dimensions of the two filters fabricated by low-temperature co-fired ceramic are 1.6 mm × 1.05 mm × 0.67 mm and 1.6 mm × 0.8 mm × 0.56 mm, respectively. For the simulation results, the maximum insertion losses for the first and second filters are 2.2 and 2.3 dB in the 2.4-GHz band, respectively. Common mode rejection for both is more than 22 dB in the same band. The amplitude imbalance and phase imbalance for the first filter are less than 1.8 dB and 6.8 in the passband, respectively. The amplitude imbalance and phase imbalance for the second filter are less than 1.9 dB and 1.8 in the passband, respectively. For both design methods, good agreement between measured and computed results is obtained. © 2011 IEEE.

Lien S.-Y.,National formosa University | Chen K.-C.,National Taiwan University | Liang Y.-C.,University of Electronic Science and Technology of China | Lin Y.,IBM
IEEE Wireless Communications | Year: 2014

Wang X.-H.,University of Electronic Science and Technology of China | Zhang H.,University of North Texas | Wang B.-Z.,University of Electronic Science and Technology of China
IEEE Microwave and Wireless Components Letters | Year: 2013

A novel differential filter with ultra-wideband (UWB) response is proposed in this letter based on microstrip line structures. 180° UWB phase shifters and 360° transmission lines are employed in the design to get the 180° phase shift over broad bandwidth. In this way, the broadband conversion between in- and out-of-phase signals can be realized. Utilizing this characteristic, the undesired common-mode noises will be cancelled out at the center of the filter, while the input differential-mode signals can still propagate well. The proposed new differential filter was calculated by transmission line model, simulated by full-wave electromagnetic simulator, and validated by the measurement. The simulation and measurement results verify its good performance. It is validated that, in the proposed filter, the differential-mode signals can propagate well with UWB frequency response, while the common-mode noises are well suppressed with more than 10 dB suppression in the concerned frequency band. © 2001-2012 IEEE.

Yang K.,University of Electronic Science and Technology of China | Gao S.,University of Electronic Science and Technology of China | Li C.,University of Electronic Science and Technology of China | Li C.,CAS Shanghai Institutes for Biological Sciences | Li Y.,University of Electronic Science and Technology of China
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2013

Color information plays an important role in better understanding of natural scenes by at least facilitating discriminating boundaries of objects or areas. In this study, we propose a new framework for boundary detection in complex natural scenes based on the color-opponent mechanisms of the visual system. The red-green and blue-yellow color opponent channels in the human visual system are regarded as the building blocks for various color perception tasks such as boundary detection. The proposed framework is a feed forward hierarchical model, which has direct counterpart to the color-opponent mechanisms involved in from the retina to the primary visual cortex (V1). Results show that our simple framework has excellent ability to flexibly capture both the structured chromatic and achromatic boundaries in complex scenes. © 2013 IEEE.

Cermak T.,University of Minnesota | Doyle E.L.,Iowa State University | Christian M.,University of Minnesota | Wang L.,Iowa State University | And 8 more authors.
Nucleic Acids Research | Year: 2011

TALENs are important new tools for genome engineering. Fusions of transcription activator-like (TAL) effectors of plant pathogenic Xanthomonas spp. to the FokI nuclease, TALENs bind and cleave DNA in pairs. Binding specificity is determined by customizable arrays of polymorphic amino acid repeats in the TAL effectors. We present a method and reagents for efficiently assembling TALEN constructs with custom repeat arrays. We also describe design guidelines based on naturally occurring TAL effectors and their binding sites. Using software that applies these guidelines, in nine genes from plants, animals and protists, we found candidate cleavage sites on average every 35bp. Each of 15 sites selected from this set was cleaved in a yeast-based assay with TALEN pairs constructed with our reagents. We used two of the TALEN pairs to mutate HPRT1 in human cells and ADH1 in Arabidopsis thaliana protoplasts. Our reagents include a plasmid construct for making custom TAL effectors and one for TAL effector fusions to additional proteins of interest. Using the former, we constructed de novo a functional analog of AvrHah1 of Xanthomonas gardneri. The complete plasmid set is available through the non-profit repository AddGene and a web-based version of our software is freely accessible online. © 2011 The Author(s).

Xing L.,University of Electronic Science and Technology of China | Xing L.,University of Massachusetts Dartmouth | Tannous O.,University of Massachusetts Dartmouth | Dugan J.B.,University of Virginia
IEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans | Year: 2012

Many real-world systems, particularly those with limited power resources, are designed with cold-standby redundancy for achieving fault tolerance and high reliability. Cold-standby units are unpowered and, thus, do not consume any power until needed to replace a faulty online component. Cold-standby redundancy creates sequential dependence between the online component and standby components; in particular, a standby component can start to work and then fail only after the online component has failed. Traditional approaches to handling the cold-standby redundancy are typically state-space-based or simulation-based or inclusion/exclusion-based methods. Those methods, however, have the state-space explosion problem and/or require long computation time particularly when results with a high degree of accuracy are desired. In this paper, we propose an analytical method based on sequential binary decision diagrams (SBDD) for combinatorial reliability analysis of nonrepairable cold-standby systems. Different from the simulation-based methods, the proposed approach can generate exact system reliability results. In addition, the system SBDD model and reliability evaluation expression, once generated, are reusable for the reliability analysis with different component failure parameters. The approach has no limitation on the type of time-to-failure distributions for the system components or on the system structure. Application and advantages of the proposed approach are illustrated through several case studies. © 2012 IEEE.

Yang T.,University of Electronic Science and Technology of China | Yang T.,University of California at Los Angeles | Chi P.-L.,University of California at Los Angeles | Itoh T.,University of California at Los Angeles
IEEE Microwave and Wireless Components Letters | Year: 2010

In this letter, a compact microstrip diplexer with very high output isolation is proposed. This diplexer consists of compact hybrid resonators, which are capable of introducing transmission zeros at desired frequencies and meanwhile suppressing signals below the resonant frequencies through tapping the feeding line close to the shorted vias. By designing the transmission zero of the lower-frequency channel in the higher passband, and utilizing the high lower-stopband suppression property of the higher-frequency channel, very high diplexer output isolation can be achieved. The proposed diplexer with center frequencies at 1.8 and 2.45 GHz, respectively, has demonstrated better than 55 dB output isolation and more than 55 dB suppressions in the stopbands. Furthermore, the diplexer occupies only a small area of 0.13λ0 × 0.2λ0. © 2010 IEEE.

Yang T.,University of California at Los Angeles | Yang T.,University of Electronic Science and Technology of China | Tamura M.,Panasonic | Itoh T.,University of California at Los Angeles
IEEE Transactions on Microwave Theory and Techniques | Year: 2010

A hybrid resonant circuit is proposed in this paper. The circuit is a combination of a shunt resonant circuit and series resonant circuit. With this combination, lower resonant frequency is achieved as compared to the single shunt and series resonant circuits. As a result, a compact resonator with smaller size can be achieved as compared to the conventional quarter- and half-wave resonators. Besides the size reduction, the proposed resonant circuit is able to introduce a transmission zero to improve the stopband suppression in filter design. Based on this circuit, a very compact interdigital coupled microstrip resonator is proposed in this paper. The resonator achieves a small length of nearly 1/10 guided wavelength λg, which has a length reduction of 63% as compared to the conventional uniform quarter-wave resonator. By using the proposed resonator, a second-order bandpass filter with a small size of 0.144λg × 0.128λg and a fourth-order bandpass filter with a size of 0.217λg × 0.1λg are built based on the standard filter synthesis methods. Both good performance and miniaturization are achieved for the proposed filters, and the expected transmission zeros are also observed. In addition to the small filters, the proposed resonator is suitable for miniaturized balun bandpass filters. A novel configuration for a balun bandpass filter is proposed based on the aforementioned resonators. A second-order balun bandpass filter with a size of 0.26λg × 0.145λg and a fourth-order balun bandpass filter with a size of 0.213λg × 0.203λg are reported in this paper. Both balun filters achieve good filtering performance, as well as excellent amplitude and phase imbalances, which are less than 1 dB and 1° in the passband, respectively. © 2010 IEEE.

Zhang L.,Northwestern University | Zhang L.,Qualcomm | Li H.,University of Electronic Science and Technology of China | Guo D.,Northwestern University
IEEE Transactions on Information Theory | Year: 2014

In many wireless communication systems, radios are subject to a duty cycle constraint, that is, a radio can only actively transmit signals over a fraction of the time. For example, it is desirable to have a small duty cycle in some low power systems; a half-duplex radio cannot keep transmitting if it wishes to receive useful signals; and a cognitive radio needs to listen and detect primary users frequently. This paper studies the capacity of point-to-point scalar discrete-time Gaussian channels subject to a duty cycle constraint as well as an average transmit power constraint. An idealized duty cycle constraint is first studied, which can be regarded as a requirement on the minimum fraction of nontransmissions or zero symbols in each codeword. Independent input with a unique discrete distribution is shown to achieve the channel capacity. In many situations, numerically optimized on-off signaling can achieve much higher rate than Gaussian signaling over a deterministic transmission schedule. This is in part because the positions of nontransmissions in a codeword can convey information. A more realistic duty cycle constraint is also studied, where the extra cost of transitions between transmissions and nontransmissions due to pulse shaping is accounted for. The capacity-achieving input is correlated over time and is hard to compute. A lower bound of the achievable rate as a function of the input distribution is shown to be maximized by a first-order Markov input process, whose stationary distribution is also discrete and can be computed efficiently. The results in this paper suggest that, under various duty cycle constraints, departing from the usual paradigm of intermittent packet transmissions may yield substantial gain. © 1963-2012 IEEE.

Li L.,University of California at Los Angeles | Li L.,University of Electronic Science and Technology of China | Yu Z.,University of California at Los Angeles | Hu W.,University of California at Los Angeles | And 3 more authors.

Blue, green, and red electrophosphorescent polymer light-emitting diodes have been fabricated on silver nanowire-polymer composite electrode. The devices are 20%-50% more efficient than control devices on ITO/glass and exhibit small efficiency roll-off at high luminances. The blue PLEDs were repeatedly bent to 1.5 mm radius concave or convex with calculated strain in the emissive layer approximately 5% (tensile or compressive). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lan F.,University of Electronic Science and Technology of China | Yang Z.,University of Electronic Science and Technology of China | Qi L.,Qufu Normal University | Gao X.,Guilin University of Electronic Technology | Shi Z.,University of Electronic Science and Technology of China
Optics Letters | Year: 2014

A dual-resonance frequency selective surface filter in the THz range that uses bilayer modified complementary metamaterial structures is proposed in this Letter. The bandpass filter, with dual bands centered at 0.315 and 0.48 THz, uses a single crystal quartz substrate and is simulated, fabricated, and measured. To minimize the manufacturing risks of working with fragile and thin quartz substrates, efforts have been made to improve the transmission frequency response features at realizable substrate thicknesses. Experimental results from 0.1 to 0.6 THz measured by THz time-domain spectroscopy show excellent agreement with the simulation results. © 2014 Optical Society of America.

Fan L.,CAS Institute of Automation | Wang J.,University of Electronic Science and Technology of China | Zhang Y.,CAS Institute of Automation | Han W.,Tianjin Medical University | And 4 more authors.
Cerebral Cortex | Year: 2014

The temporal pole (TP) is an association cortex capable of multisensory integration and participates in various high-order cognitive functions. However, an accepted parcellation of the human TP and its connectivity patterns have not yet been well established. Here, we sought to present a scheme for the parcellation of human TP based on anatomical connectivity and to reveal its subregional connectivity patterns. Three distinct subregions with characteristic fiber pathways were identified, including the dorsal (TAr), the medial (TGm), and lateral (TGl) subregions, which are located ventrally. According to the connectivity patterns, a dorsal/ventral sensory segregation of auditory and visual processing and the medial TGm involved in the olfactory processing were observed. Combined with the complementary resting-state functional connectivity analysis, the connections of the TGm with the orbitofrontal cortex and other emotion-related areas, the TGl connections with the MPFC and major default mode network regions, and the TAr connections with the perisylvian language areas were observed. To the best of our knowledge, the present study represents the first attempt to parcel the human TP based on its anatomical connectivity features, which may help to improve our understanding of its connectional anatomy and to extend the available knowledge in TP-related clinical research. © The Author 2013. Published by Oxford University Press. All rights reserved.

He Q.,University of Electronic Science and Technology of China | He Q.,Lehigh University | Blum R.S.,Lehigh University | Haimovich A.M.,New Jersey Institute of Technology
IEEE Transactions on Signal Processing | Year: 2010

This paper presents an analysis of the joint estimation of target location and velocity using a multiple-input multiple-output (MIMO) radar employing noncoherent processing for a complex Gaussian extended target. A MIMO radar with M transmit and $N$ receive antennas is considered. To provide insight, we focus on a simplified case first, assuming orthogonal waveforms, temporally and spatially white noise-plus-clutter, and independent reflection coefficients. Under these simplifying assumptions, the maximum-likelihood (ML) estimate is analyzed, and a theorem demonstrating the asymptotic consistency, large MN, of the ML estimate is provided. Numerical investigations, given later, indicate similar behavior for some reasonable cases violating the simplifying assumptions. In these initial investigations, we study unconstrained systems, in terms of complexity and energy, where each added transmit antenna employs a fixed energy so that the total transmitted energy is allowed to increase as we increase the number of transmit antennas. Following this, we also look at constrained systems, where the total system energy and complexity are fixed. To approximate systems of fixed complexity in an abstract way, we restrict the total number of antennas employed to be fixed. Here, we show numerical examples which indicate a preference for receive antennas, similar to MIMO communications, but where systems with multiple transmit antennas yield the smallest possible mean-square error (MSE). The joint CramrRao bound (CRB) is calculated and the MSE of the ML estimate is analyzed. It is shown for some specific numerical examples that the signal-to-clutter-plus-noise ratio (SCNR) threshold, indicating the SCNRs above which the MSE of the ML estimate is reasonably close to the CRB, can be lowered by increasing MN. The noncoherent MIMO radar ambiguity function (AF) is developed in two different ways and illustrated by examples. It is shown for some specific examples that the size of the product MN controls the levels of the sidelobes of the AF. © 2010 IEEE.

He Q.,University of Electronic Science and Technology of China | Blum R.S.,Lehigh University
IEEE Signal Processing Letters | Year: 2014

Target position and velocity estimation using a passive radar with multiple signals of opportunity and multiple receive stations is investigated. The maximum likelihood (ML) estimate of the unknown position and velocity vector of a target is presented. Formulas bounding the best possible mean square error are provided, via the Cramer-Rao lower bound, for any unbiased estimator of target position and velocity. The model assumes a single target, a single receive antenna at each receive station, spatially and temporally white Gaussian clutter-plus-noise, and uncorrelated reflection coefficients. To describe the best possible performance, it is assumed that the signals of opportunity are estimated perfectly from the direct path reception. For a specific example where the signals of opportunity come from the Global System for Mobile (GSM) communication system, the optimum possible estimation performance is presented using numerical examples. It is shown that it is possible to obtain large performance gains through using multiple signals of opportunity and multiple receive stations. © 2013 IEEE.

He Q.,University of Electronic Science and Technology of China | He Q.,Lehigh University | Blum R.S.,Lehigh University | Godrich H.,New Jersey Institute of Technology | Haimovich A.M.,New Jersey Institute of Technology
IEEE Journal on Selected Topics in Signal Processing | Year: 2010

This paper studies the velocity estimation performance for multiple-input multiple-output (MIMO) radar with widely spaced antennas. We derive the Cramer Rao bound (CRB) for velocity estimation and study the optimized system/configuration design based on CRB. General results are presented for an extended target with reflectivity varying with look angle. Then detailed analysis is provided for a simplified case, assuming an isotropic scatterer. For given transmitted signals, optimal antenna placement is analyzed in the sense of minimizing the CRB of the velocity estimation error. We show that when all antennas are located at approximately the same distance from the target, symmetrical placement is optimal and the relative position of transmitters and receivers can be arbitrary under the orthogonal received signal assumption. In this case, it is also shown that for MIMO radar with optimal placement, velocity estimation accuracy can be improved by increasing either the signal time duration or the product of the number of transmit and receive antennas. © 2010 IEEE.

He Q.,University of Electronic Science and Technology of China | He Q.,Lehigh University | Blum R.S.,Lehigh University
IEEE Transactions on Signal Processing | Year: 2011

For a multiple-input multiple-output (MIMO) system adopting the NeymanPearson (NP) criterion, we initially derive the diversity gain for a signal-present versus signal-absent scalar hypothesis test statistic and also for a vector signal-present versus signal-absent hypothesis testing problem. For a MIMO radar system with M transmit and N receive antennas, used to detect a target composed of Q random scatterers with possibly non-Gaussian reflection coefficients in the presence of possibly non-Gaussian clutter-plus-noise, we consider a class of test statistics, including the optimum test for Gaussian reflection coefficients and Gaussian clutter-plus-noise, and apply the previously developed results to compute the diversity gain. It is found that the diversity gain for the MIMO radar system is dependent on the cumulative distribution function (cdf) of the reflection coefficients while being invariant to the cdf of the clutter-plus-noise under some reasonable conditions requiring certain moments of the magnitude of the processed clutter-plus-noise be bounded. If the noise-free received waveforms, due to target reflection, at each receiver span a space of dimension M' ≤ M, the largest possible diversity gain is controlled by the value of min (N M', Q and the lowest order power in an expansion, about zero, of the cdf of the magnitude squared of a linear transformed version of the reflection coefficient vector. It is shown that the maximum possible diversity gain in any given scenario can be achieved without employing orthogonal waveforms. © 2006 IEEE.

Wang H.,Rutgers University | Zou Q.,Rutgers University | Xu H.,University of Electronic Science and Technology of China
Automatica | Year: 2012

In this article, the problem of nonperiodic tracking-transition switching with preview is considered. Such a control problem exists in applications including nanoscale material property mapping, robot manipulation, and probe-based nanofabrication, where the output needs to track the desired trajectory during the tracking sections, and rapidly transit to another point during the transition sections with no post-transition oscillations. Due to the coupling between the control of the tracking sections and that of the transition ones, and the potential mismatch of the boundary system state at the tracking-transition switching instants, these control objectives become challenging for nonminimum-phase systems. In the proposed approach, the optimal desired output trajectory for the transition sections is designed through a direct minimization of the output energy, and the needed control input that maintains the smoothness of both the output and the system state across all tracking-transition switching is obtained through a preview-based stable-inversion approach. The needed preview time is quantified by the characteristics of the system dynamics, and can be minimized via the recently developed optimal preview-based inversion technique. The proposed approach is illustrated through a nanomanipulation example in simulation. © 2012 Elsevier Ltd. All rights reserved. © 2012 Elsevier Ltd. All rights reserved.

Xi L.,University of Electronic Science and Technology of China | Jiang H.,University of Electronic Science and Technology of China | Jiang H.,University of Florida
Applied Physics Letters | Year: 2015

We present a method for noninvasively imaging the hand joints using a three-dimensional (3D) photoacoustic imaging (PAI) system. This 3D PAI system utilizes cylindrical scanning in data collection and virtual-detector concept in image reconstruction. The maximum lateral and axial resolutions of the PAI system are 70μm and 240μm. The cross-sectional photoacoustic images of a healthy joint clearly exhibited major internal structures including phalanx and tendons, which are not available from the current photoacoustic imaging methods. The in vivo PAI results obtained are comparable with the corresponding 3.0T MRI images of the finger joint. This study suggests that the proposed method has the potential to be used in early detection of joint diseases such as osteoarthritis. © 2015 AIP Publishing LLC.

Li J.,Aston University | Li J.,University of Electronic Science and Technology of China | Sun Z.,Aston University | Luo H.,University of Electronic Science and Technology of China | And 4 more authors.
Optics Express | Year: 2014

We demonstrate an all-fiber Tm3+-doped silica fiber laser operating at a wide selectable wavelength range by using different fiber Bragg gratings (FBGs) as wavelength selection elements. With a specifically designed high reflective (HR) FBG and the fiber end as an output coupler, the lasing in the range from 1975 nm to 2150 nm with slope efficiency of >30% can be achieved. By employing a low reflective (LR) FBG as the output coupler, the obtainable wavelengths were extended to the range between 1925 nm and 2200 nm which is the reported longest wavelength from the Tm3+-doped silica fiber lasers. Furthermore, by employing a FBG array in the laser cavity and inducing bend loss between adjacent FBGs in the array, six switchable lasing wavelengths were achieved. © 2014 Optical Society of America.

He Q.,University of Electronic Science and Technology of China | Blum R.S.,Lehigh University
IEEE Signal Processing Letters | Year: 2010

Recent research indicates the potential of MIMO radar with dispersed antennas to achieve high target localization accuracy via coherent processing. Coherent processing requires phase synchronization. Usually, perfect phase synchronization is difficult to realize. Assuming frequency synchronization, possibly through reception of a beacon, and white noise, possibly due to estimating the covariance matrix and whitening the observations, we consider the impact of static phase errors at the transmitters and receivers for cases with sufficiently high SNR such that the Cramer-Rao bound (CRB) provides accurate performance estimates. We model the phase errors as random variables and discuss the impact of these errors on target localization performance. In a few example cases the CRB is computed and compared with those in the ideal coherent and noncoherent processing cases. For these examples, using numerical results, we will show that at high enough signal-to-noise ratio (SNR), phase errors degrade performance only by a relatively small amount. © 2009 IEEE.

Chen F.,University of Electronic Science and Technology of China | Zhang Y.,Sichuan Remote Sensing Geomatics Institute
IEEE Geoscience and Remote Sensing Letters | Year: 2013

Linear spectral unmixing is an effective technique to estimate the abundances of materials present in each hyperspectral image pixel. Recently, sparse-regression-based unmixing approaches have been proposed to tackle this problem. Mostly, ℓ1 norm minimization is used to approximate the ℓ0 norm minimization problem in terms of computational complexity. In this letter, we model the hyperspectral unmixing as a constrained sparse ℓp - ℓ2(0 < p < 1) optimization problem and propose to solve it via the iteratively reweighted least squares algorithm. Experimental results on a series of simulated data sets and a real hyperspectral image demonstrate that the proposed method can achieve performance improvement over the state-of-the-art ℓ1 -ℓ2 method. © 2012 IEEE.

Wu G.-R.,Ghent University | Wu G.-R.,University of Electronic Science and Technology of China | Marinazzo D.,Ghent University
Brain Topography | Year: 2015

It is now recognized that important information can be extracted from the brain spontaneous activity, as exposed by recent analysis using a repertoire of computational methods. In this context a novel method, based on a blind deconvolution technique, is used to analyze potential changes due to chronic pain in the brain pain matrix’s effective connectivity. The approach is able to deconvolve the hemodynamic response function from spontaneous neural events, i.e., in the absence of explicit onset timings, and to evaluate information transfer between two regions as a joint probability of the occurrence of such spontaneous events. The method revealed that the chronic pain patients exhibit important changes in the insula’s effective connectivity which can be relevant to understand the overall impact of chronic pain on brain function. © 2014, Springer Science+Business Media New York.

He Q.,University of Electronic Science and Technology of China | Blum R.S.,Lehigh University
Signal Processing | Year: 2012

MIMO radar with properly placed antennas that employs a coherent processing approach can provide superior MSE performance, as indicated by recent work. This paper demonstrates that the magnitude of these gains decreases with an increase in the product of the number of transmit and receive antennas if the antennas for the noncoherent system are also suitably placed, using a placement which is generally different from the one for the coherent processing approach. Initially, we study the systems without constraining the complexity and energy, where each added transmit antenna employs a fixed energy so that the total transmitted energy is allowed to increase as we increase the number of transmit antennas. Later we also look at constrained systems, where adding a transmit antenna splits the total system energy and the total number of antennas employed is restricted. A rigorous theorem is presented for the case of orthogonal signals in temporally and spatially white clutter-plus-noise, but numerical results for nonorthogonal signals and colored clutter-plus-noise follow a similar pattern. © 2012 Elsevier B.V. All rights reserved.

Wang W.,University of Electronic Science and Technology of China | Li G.-X.,Harbin Institute of Technology
Engineering Failure Analysis | Year: 2012

With an increase in speed, a vehicle's dynamic behavior becomes apparent. Increasing speed not only affects the sitting comfort, but also may lead to derailment. However, an accident is difficult to predict, because the derailment mechanism is not thoroughly understood. The reliability of derailment simulations are completely conditional to being able to accurately solve the wheel and rail contact problem. Thus, an improved three-dimensional contact trace method is presented to quickly obtain the correct point. Then, a fast and accurate method for obtaining the contact force, which includes the creep force and the normal force, is improved. The results correspond more closely to realitic solutions compared with those of current methods. Next, a dynamic model of the vehicle and the rail is established. The two models are not independent of each other. The wheel-rail contact calculation is the key consideration for coupling in the two models. Finally, all the dynamic models, which are called dynamic derailment simulation for high-speed vehicle (DDSHV), are developed in MATLAB. To identify two different types of derailment, derailment judgment is embedded in the program package. The simulation system can be used to study the dynamic derailment mechanism, analyze derailment conditions and influence factors, and determine the key cause of the incident. © 2012 Elsevier Ltd.

Yang Y.,Lehigh University | Blum R.S.,Lehigh University | He Z.,University of Electronic Science and Technology of China | Fuhrmann D.R.,Michigan Technological University
IEEE Transactions on Signal Processing | Year: 2010

Waveform design is essential to unleash the performance advantages promised by multiple-input multiple-output (MIMO) radar, and this topic has attracted a lot of attention in the recent years. Revisiting an earlier examined MIMO radar waveform design problem that optimizes both minimum mean-square error estimation (MMSE) and mutual information (MI), in this correspondence we formulate a new waveform design problem and provide some further results, which complement the previous study. More specifically, we present an iterative optimization algorithm based on the alternating projection method to determine waveform solutions that can simultaneously satisfy a structure constraint and optimize the design criteria. Numerical examples are provided, which illustrate the effectiveness of the proposed approach. In particular, we find that the waveform solutions obtained through our proposed algorithm can achieve very close and virtually indistinguishable performance from that predicted in the previous study. © 2010 IEEE.

Chen Y.,University of Electronic Science and Technology of China | Chen Y.,Huaibei Normal University | Wang B.-Z.,University of Electronic Science and Technology of China
Optics Express | Year: 2013

Polycentric focus effect of time-reversal (TR) electromagnetic field is found in a rectangular resonant cavity. Theoretical deduction shows that the effect is due to the mirror symmetry of the cavity and the maximum number of focus points is 27 including 1 main focus point and 26 secondary focus points. A case of 6 focus points is calculated, in which the numerical results are consistent with the theoretical predictions, and particularly the 5 secondary focus points have directly resulted in inaccurate imaging and pulse signal interception. © Optical Society of America 2013.

Chen Y.,University of Electronic Science and Technology of China | Chen Y.,Huaibei Normal University | Wang B.-Z.,University of Electronic Science and Technology of China
Optics Express | Year: 2013

Current experimental investigations about time reversal (TR) electromagnetic (EM) fields always depended on TR mirror (TRM). However, EM fields can perform reversal operation invariance in four domains connected by Fourier Transform. A multiplication table and an appropriate operating figure about EM fields' invariance are derived to describe a series of dual combined operations in the four domains, in which there are at least 10 dual-combination operations different from current TRM operations which can equivalently actualize TR symmetry. Theoretically, centrosymmetric operations of spatial position vector and spatial spectrum vector may have the potential to promote different reversal mirrors. © 2013 Optical Society of America.

Liu Y.,University of Electronic Science and Technology of China | Mei T.,Microsoft
IEEE Transactions on Multimedia | Year: 2011

Visual search reranking is defined as reordering visual documents (images or video clips) based on the initial search results or some auxiliary knowledge to improve the search precision. Conventional approaches to visual search reranking empirically take the "classification performance" as the optimization objective, in which each visual document is determined relevant or not, followed by a process of increasing the order of relevant documents. In this paper, we first show that the classification performance fails to produce a globally optimal ranked list, and then we formulate reranking as an optimization problem, in which a ranked list is globally optimal only if any arbitrary two documents in the list are correctly ranked in terms of relevance. This is different from existing approaches which simply classify a document as "relevant" or not. To find the optimal ranked list, we convert the individual documents to "document pairs," each represented as a "ordinal relation." Then, we find the optimal document pairs which can maximally preserve the initial rank order while simultaneously keeping the consistency with the auxiliary knowledge mined from query examples and web resources as much as possible. We develop two pairwise reranking methods, difference pairwise reranking (DP-reranking) and exclusion pairwise reranking (EP-reranking), to obtain the relevant relation of each document pair. Finally, a round robin criterion is explored to recover the final ranked list. We conducted comprehensive experiments on an automatic video search task over TRECVID 2005-2007 benchmarks, and showed consistent improvements over text search baseline and other reranking approaches. © 2011 IEEE.

Zhao X.-L.,University of Electronic Science and Technology of China | Wang F.,Lanzhou University | Huang T.-Z.,University of Electronic Science and Technology of China | Ng M.K.,Hong Kong Baptist University | Plemmons R.J.,Wake forest University
IEEE Transactions on Geoscience and Remote Sensing | Year: 2013

The main aim of this paper is to study total variation (TV) regularization in deblurring and sparse unmixing of hyperspectral images. In the model, we also incorporate blurring operators for dealing with blurring effects, particularly blurring operators for hyperspectral imaging whose point spread functions are generally system dependent and formed from axial optical aberrations in the acquisition system. An alternating direction method is developed to solve the resulting optimization problem efficiently. According to the structure of the TV regularization and sparse unmixing in the model, the convergence of the alternating direction method can be guaranteed. Experimental results are reported to demonstrate the effectiveness of the TV and sparsity model and the efficiency of the proposed numerical scheme, and the method is compared to the recent Sparse Unmixing via variable Splitting Augmented Lagrangian and TV method by Iordache © 1980-2012 IEEE.

Yang P.,University of Electronic Science and Technology of China | Di Renzo M.,French National Center for Scientific Research | Xiao Y.,University of Electronic Science and Technology of China | Li S.,University of Electronic Science and Technology of China | Hanzo L.,University of Southampton
IEEE Communications Surveys and Tutorials | Year: 2015

A new class of low-complexity, yet energy-efficient Multiple-Input Multiple-Output (MIMO) transmission techniques, namely, the family of Spatial Modulation (SM) aided MIMOs (SM-MIMO), has emerged. These systems are capable of exploiting the spatial dimensions (i.e., the antenna indices) as an additional dimension invoked for transmitting information, apart from the traditional Amplitude and Phase Modulation (APM). SM is capable of efficiently operating in diverse MIMO configurations in the context of future communication systems. It constitutes a promising transmission candidate for large-scale MIMO design and for the indoor optical wireless communication while relying on a single-Radio Frequency (RF) chain. Moreover, SM may be also viewed as an entirely new hybrid modulation scheme, which is still in its infancy. This paper aims for providing a general survey of the SM design framework as well as of its intrinsic limits. In particular, we focus our attention on the associated transceiver design, on spatial constellation optimization, on link adaptation techniques, on distributed/cooperative protocol design issues, and on their meritorious variants. © 1998-2012 IEEE.

Xiong L.,Yunnan Nationalities University | Tian J.,University of Electronic Science and Technology of China | Liu X.,University of Waterloo
Journal of the Franklin Institute | Year: 2012

This paper addresses the problem of the delay-dependent stability for neutral Markovian jump systems with partial information on transition probability. The time delays discussed in this paper are time-varying delays. Combined the new constructed Lyapunov functional with the introduced free matrices, and using the analysis technique of matrix inequalities, the delay-dependent stability conditions are obtained. The obtained results are formulated in terms of LMIs, which can be easily checked in practice by Matlab LMI control toolbox. Three numerical examples are given to show the validity and potential of the developed criteria. © 2012 The Franklin Institute. All rights reserved.

Tian X.,University of Electronic Science and Technology of China | Tao D.,Nanyang Technological University | Hua X.-S.,Microsoft | Wu X.,University of Electronic Science and Technology of China
IEEE Transactions on Image Processing | Year: 2010

Image search reranking methods usually fail to capture the user's intention when the query term is ambiguous. Therefore, reranking with user interactions, or active reranking, is highly demanded to effectively improve the search performance. The essential problem in active reranking is how to target the user's intention. To complete this goal, this paper presents a structural information based sample selection strategy to reduce the user's labeling efforts. Furthermore, to localize the user's intention in the visual feature space, a novel local-global discriminative dimension reduction algorithm is proposed. In this algorithm, a submanifold is learned by transferring the local geometry and the discriminative information from the labelled images to the whole (global) image database. Experiments on both synthetic datasets and a real Web image search dataset demonstrate the effectiveness of the proposed active reranking scheme, including both the structural information based active sample selection strategy and the local-global discriminative dimension reduction algorithm. © 2010 IEEE.

Vasan A.S.S.,University of Maryland University College | Long B.,University of Electronic Science and Technology of China | Pecht M.,University of Maryland University College | Pecht M.,City University of Hong Kong
IEEE Transactions on Industrial Electronics | Year: 2013

Analog circuits play a vital role in ensuring the availability of industrial systems. Unexpected circuit failures in such systems during field operation can have severe implications. To address this concern, we developed a method for detecting faulty circuit condition, isolating fault locations, and predicting the remaining useful performance of analog circuits. Through the successive refinement of the circuit's response to a sweep signal, features are extracted for fault diagnosis. The fault diagnostics problem is posed and solved as a pattern recognition problem using kernel methods. From the extracted features, a fault indicator (FI) is developed for failure prognosis. Furthermore, an empirical model is developed based on the degradation trend exhibited by the FI. A particle filtering approach is used for model adaptation and RUP estimation. This method is completely automated and has the merit of implementation simplicity. Case studies on two analog filter circuits demonstrating this method are presented. © 1982-2012 IEEE.

Ng M.K.,Hong Kong Baptist University | Yuan X.,Hong Kong Baptist University | Zhang W.,University of Electronic Science and Technology of China
IEEE Transactions on Image Processing | Year: 2013

In this paper, we develop a decomposition model to restore blurred images with missing pixels. Our assumption is that the underlying image is the superposition of cartoon and texture components. We use the total variation norm and its dual norm to regularize the cartoon and texture, respectively. We recommend an efficient numerical algorithm based on the splitting versions of augmented Lagrangian method to solve the problem. Theoretically, the existence of a minimizer to the energy function and the convergence of the algorithm are guaranteed. In contrast to recently developed methods for deblurring images, the proposed algorithm not only gives the restored image, but also gives a decomposition of cartoon and texture parts. These two parts can be further used in segmentation and inpainting problems. Numerical comparisons between this algorithm and some state-of-the-art methods are also reported. © 1992-2012 IEEE.

Li Z.,Cisco Systems | Gong G.,University of Waterloo | Qin Z.,University of Electronic Science and Technology of China
IEEE Transactions on Information Theory | Year: 2013

The simple, computationally efficient HB-like entity authentication protocols based on the learning parity with noise (LPN) problem have attracted a great deal of attention in the past few years due to the broad application prospect in low-cost RFID tags. However, all previous protocols are vulnerable to a man-in-the-middle attack discovered by Ouafi, Overbeck, and Vaudenay. In this paper, we propose a lightweight authentication protocol named LCMQ and prove it secure in a general man-in-the-middle model. The technical core in our proposal is a special type of circulant matrix, for which we prove the linear independence of matrix vectors, present efficient algorithms on matrix operations, and describe a secure encryption against ciphertext-only attack. By combining all of those with LPN and related to the multivariate quadratic problem, the LCMQ protocol not only is provably secure against all probabilistic polynomial-time adversaries, but also transcends HB-like protocols in terms of tag's computation overhead, storage expense, and communication cost. © 1963-2012 IEEE.

Lu Q.,University Pierre and Marie Curie | Lu Q.,University of Electronic Science and Technology of China
Inverse Problems | Year: 2013

This paper is devoted to a study of the boundary and internal state observation problems for stochastic hyperbolic equations. For this, we derive a boundary and an internal observability inequality for stochastic hyperbolic equations with nonsmooth lower order terms. The required inequalities are obtained by the global Carleman estimate for stochastic hyperbolic equations. By these inequalities, we get stability estimates for the state observation problems. As a consequence, we also establish a unique continuation property for stochastic hyperbolic equations. © 2013 IOP Publishing Ltd.

Wang D.,City University of Hong Kong | Miao Q.,University of Electronic Science and Technology of China | Pecht M.,University of Maryland University College
Journal of Power Sources | Year: 2013

Lithium-ion batteries are widely used as power sources in commercial products, such as laptops, electric vehicles (EVs) and unmanned aerial vehicles (UAVs). In order to ensure a continuous power supply, the functionality and reliability of lithium-ion batteries have received considerable attention. In this paper, a battery capacity prognostic method is developed to estimate the remaining useful life of lithium-ion batteries. This capacity prognostic method consists of a relevance vector machine and a conditional three-parameter capacity degradation model. The relevance vector machine is used to derive the relevance vectors that can be used to find the representative training vectors containing the cycles of the relevance vectors and the predictive values at the cycles of the relevance vectors. The conditional three-parameter capacity degradation model is developed to fit the predictive values at the cycles of the relevance vectors. Extrapolation of the conditional three-parameter capacity degradation model to a failure threshold is used to estimate the remaining useful life of lithium-ion batteries. Three instance studies were conducted to validate the developed method. The results show that the developed method is able to predict the future health condition of lithium-ion batteries. © 2013 Elsevier B.V. All rights reserved.

Xiao Y.,University of Electronic Science and Technology of China | Tylecote A.,University of Sheffield | Liu J.,University of Manchester
Research Policy | Year: 2013

How can 'late-comer firms' (LCFs) in developing economies manage their development of technological capability, and within it their IP, strategically, in order to become fully competitive internationally? Under what conditions, external and internal, are they likely to succeed? This paper develops a theoretical framework for understanding LCFs' technology strategy and predicting its outcome, then applies it to the cases of three Chinese firms in sectors at different levels of technology intensity. This yields insights as to its limitations and further development. These help explain mainland China's very limited catch-up in high technology sectors-and to a lesser extent in medium-high technology. We show how our findings can be reconciled with the much greater success of Korean firms some 20 years earlier, if the effect of corporate governance differences is recognised. © 2012 Elsevier B.V.

Sasaki T.,University of Vienna | Uchida S.,RINRI Institute | Chen X.,University of Electronic Science and Technology of China
Scientific Reports | Year: 2015

Punishment is a popular tool when governing commons in situations where free riders would otherwise take over. It is well known that sanctioning systems, such as the police and courts, are costly and thus can suffer from those who free ride on other's efforts to maintain the sanctioning systems (second-order free riders). Previous game-theory studies showed that if populations are very large, pool punishment rarely emerges in public good games, even when participation is optional, because of second-order free riders. Here we show that a matching fund for rewarding cooperation leads to the emergence of pool punishment, despite the presence of second-order free riders. We demonstrate that reward funds can pave the way for a transition from a population of free riders to a population of pool punishers. A key factor in promoting the transition is also to reward those who contribute to pool punishment, yet not abstaining from participation. Reward funds eventually vanish in raising pool punishment, which is sustainable by punishing the second-order free riders. This suggests that considering the interdependence of reward and punishment may help to better understand the origins and transitions of social norms and institutions.

Wang S.,University of Electronic Science and Technology of China | Zhu Q.,University of Electronic Science and Technology of China | Zhu W.,Zhangzhou Normal University | Min F.,Zhangzhou Normal University
Information Sciences | Year: 2013

Coverings are a useful form of data, while covering-based rough sets provide an effective tool for dealing with this data. Covering-based rough sets have been widely used in attribute reduction and rule extraction. However, few quantitative analyses for covering-based rough sets have been conducted, while many advances for classical rough sets have been obtained through quantitative tools. In this paper, the upper approximation number is defined as a measurement to quantify covering-based rough sets, and a pair of upper and lower approximation operators are constructed using the approximation number. The operators not only inherit some important properties of existing approximation operators, but also exhibit some new quantitative characteristics. It is interesting to note that the upper approximation number of a covering approximation space is similar to the dimension of a vector space or the rank of a matrix. © 2012 Elsevier Inc. All rights reserved.

Cermak T.,University of Minnesota | Baltes N.J.,University of Minnesota | Cegan R.,Academy of Sciences of the Czech Republic | Zhang Y.,University of Electronic Science and Technology of China | Voytas D.F.,University of Minnesota
Genome Biology | Year: 2015

Background: The use of homologous recombination to precisely modify plant genomes has been challenging, due to the lack of efficient methods for delivering DNA repair templates to plant cells. Even with the advent of sequence-specific nucleases, which stimulate homologous recombination at predefined genomic sites by creating targeted DNA double-strand breaks, there are only a handful of studies that report precise editing of endogenous genes in crop plants. More efficient methods are needed to modify plant genomes through homologous recombination, ideally without randomly integrating foreign DNA. Results: Here, we use geminivirus replicons to create heritable modifications to the tomato genome at frequencies tenfold higher than traditional methods of DNA delivery (i.e., Agrobacterium). A strong promoter was inserted upstream of a gene controlling anthocyanin biosynthesis, resulting in overexpression and ectopic accumulation of pigments in tomato tissues. More than two-thirds of the insertions were precise, and had no unanticipated sequence modifications. Both TALENs and CRISPR/Cas9 achieved gene targeting at similar efficiencies. Further, the targeted modification was transmitted to progeny in a Mendelian fashion. Even though donor molecules were replicated in the vectors, no evidence was found of persistent extra-chromosomal replicons or off-target integration of T-DNA or replicon sequences. Conclusions: High-frequency, precise modification of the tomato genome was achieved using geminivirus replicons, suggesting that these vectors can overcome the efficiency barrier that has made gene targeting in plants challenging. This work provides a foundation for efficient genome editing of crop genomes without the random integration of foreign DNA. © 2015 Čermák et al.

Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,Interactive Digital Media Institute | Li Z.,South China University of Technology
IEEE Transactions on Automatic Control | Year: 2014

In this technical note, high dimensional integral Lyapunov functions are introduced for a class of MIMO nonlinear systems with unknown nonlinearities. First, adaptive state feedback control is presented based on the integral Lyapunov function. When only the output is measurable, by using a high-gain observer to estimate the derivative of the system output, adaptive output feedback control is also derived. The proposed control scheme provides a general approach to stabilize the MIMO plant without any restrictive assumptions. The control is continuous and ensures closed-loop stability and convergence of the tracking error to a small residual set. The size of the tracking error at steady state can be specified a priori and guaranteed by choosing the design parameters. © 1963-2012 IEEE.

Guo X.,Seoul National University | Guo X.,University of Electronic Science and Technology of China
Journal of Biophotonics | Year: 2012

Optical Surface plasmon resonance (SPR) biosensors represent the most advanced and developed optical label-free biosensor technology. Optical SPR biosensors are a powerful detection and analysis tool that has vast applications in environmental protection, biotechnology, medical diagnostics, drug screening, food safety and security. This article reviews the recent development of SPR biosensor techniques, including bulk SPR and localized SPR (LSPR) biosensors, for detecting interactions between an analyte of interest in solution and a biomolecular recognition. The concepts of bulk and localized SPs and the working principles of both sensing techniques are introduced. Major sensing advances on biorecognition elements, measurement formats, and sensing platforms are presented. Finally, the discussions on both biosensor techniques as well as comparison of both SPR sensing techniques are made. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhu W.,Zhangzhou Normal University | Wang S.,University of Electronic Science and Technology of China
International Journal of Machine Learning and Cybernetics | Year: 2011

Rough set theory is a useful tool for dealing with the vagueness, granularity and uncertainty in information systems. This paper connects generalized rough sets based on relations with matroid theory. We define the upper approximation number to induce a matroid from a relation. Therefore, many matroidal approaches can be used to study generalized rough sets based on relations. Specifically, with the rank function of the matroid induced by a relation, we construct a pair of approximation operators, namely, matroid approximation operators. The matroid approximation operators present some unique properties which do not exist in the existing approximation operators. On the other hand, we present an approach to induce a relation from a matroid. Moreover, the relationship between two inductions is studied. © 2011 Springer-Verlag.

Wang S.,University of Electronic Science and Technology of China | Zhu W.,Zhangzhou Normal University | Min F.,Zhangzhou Normal University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

In many real world applications, information blocks form a covering of a universe. Covering-based rough set theory has been proposed to deal with this type of information. It is more general and complex than classical rough set theory, hence there is much need to develop sophisticated structures to characterize covering-based rough sets. Matroids are important tools for describing graphs and linear independence of matrix theory. This paper establishes two matroidal structures of covering-based rough sets. Firstly, the transversal matroidal structure of a family of subsets of a universe is constructed. We also prove that the family of subsets of a universe is a covering if and only if the constructed transversal matroid is a normal one. Secondly, the function matroidal structure is constructed through the upper approximation number. Moreover, the relationships between the two matroidal structures are studied. Specifically, when a covering of a universe is a partition, these two matroidal structures coincide with each other. © 2011 Springer-Verlag.

Lv X.-G.,University of Electronic Science and Technology of China | Huang T.-Z.,University of Electronic Science and Technology of China | Xu Z.-B.,Xi'an Jiaotong University | Zhao X.-L.,University of Electronic Science and Technology of China
Information Sciences | Year: 2012

Reflexive boundary conditions (BCs) assume that the array values outside the viewable region are given by a symmetry of the array values inside. The reflection guarantees the continuity of the image. In fact, there are usually two choices for the symmetry: symmetry around the meshpoint and symmetry around the midpoint. The first is called whole-sample symmetry in signal and image processing, the second is half-sample. Many researchers have developed some fast algorithms for the problems of image restoration with the half-sample symmetric BCs over the years. However, little attention has been given to the whole-sample symmetric BCs. In this paper, we consider the use of the whole-sample symmetric boundary conditions in image restoration. The blurring matrices constructed from the point spread functions (PSFs) for the BCs have block Toeplitz-plus-PseudoHankel with Toeplitz-plus-PseudoHankel blocks structures. Recently, regardless of symmetric properties of the PSFs, a technique of Kronecker product approximations was successfully applied to restore images with the zero BCs, half-sample symmetric BCs and anti-reflexive BCs, respectively. All these results extend quite naturally to the whole-sample symmetric BCs, since the resulting matrices have similar structures. It is interesting to note that when the size of the true PSF is small, the computational complexity of the algorithm obtained for the Kronecker product approximation of the resulting matrix in this paper is very small. It is clear that in this case all calculations in the algorithm are implemented only at the upper left corner submatrices of the big matrices. Finally, detailed experimental results reporting the performance of the proposed algorithm are presented. © 2011 Elsevier Inc. All rights reserved.

Ai X.,University of Electronic Science and Technology of China | Chen J.,University of Winnipeg | Zhao H.,University of Electronic Science and Technology of China | Tang X.,University of Electronic Science and Technology of China
International Journal of Production Economics | Year: 2012

We examine decisions of retailers and manufacturers in two competing supply chains selling a substitutable product, with demand uncertainty, when manufacturers offer or do not offer full returns policies. We consider retailers two pricing strategies, optimal pricing and clearance pricing, and we find that full returns policies have different implications in the presence of chain-to-chain competition as compared to the case of a monopoly supply chain. The conditions under which manufacturers and retailers prefer or not prefer full returns policies are identified. © 2010 Elsevier B.V. All rights reserved.

Lv H.,University of Electronic Science and Technology of China | Lu C.,University of Electronic Science and Technology of China | Lu C.,Xi'an Jiaotong University
International Journal of Advanced Manufacturing Technology | Year: 2010

In this paper, a discrete particle swarm optimization (DPSO) algorithm is proposed to solve the assembly sequence planning (ASP) problem. To make the DPSO algorithm effective for solving ASP, some key technologies including a special coding method of the position and velocity of particles and corresponding operators for updating the position and velocity of particles are proposed and defined. The evolution performance of the DPSO algorithm with different setting of control parameters is investigated, and the performance of the proposed DPSO algorithm to solve ASP is verified through a case study. © Springer-Verlag London Limited 2010.

Zhou P.,University of Electronic Science and Technology of China | Wang C.,University of Electronic Science and Technology of China | Ren Y.,Chongqing University | Yang C.,University of Electronic Science and Technology of China | Tian F.,Southwest Jiaotong University
Current Medicinal Chemistry | Year: 2013

The recent focus on protein-protein interaction networks has increasingly been shifted towards the disruption of protein complexes, which either are mediated by the binding of a globular domain in one protein to a short peptide stretch in another, or involve flat, large, and hydrophobic interfaces that classical small-molecule agents are not always ideally suited. Rational design of therapeutic peptides with high affinity targeting such interactions has emerged as a new and promising tool in discovery of potential drug candidates against associated diseases. The design is commonly based on bioinformatics methods or molecular modeling techniques, indirectly exploiting structure-activity relationship at the level of peptide sequence or directly deriving lead entities from protein complex architecture. Here, a newly rising subfield called computational peptidology that focuses on the use of computational and theoretical approaches to treat peptiderelated problems is comprehensively reviewed on the design and discovery of peptide agents targeting protein-protein interactions. We address a systematic discussion on several representative cases in which the computational peptidology is successfully employed to develop peptide therapeutics. Besides, some problems and pitfalls accompanied with the current use of computational methods in peptide modeling and design are also present. © 2013 Bentham Science Publishers.

Li F.,Southwest Jiaotong University | Li Y.,University of Electronic Science and Technology of China
Procedia Engineering | Year: 2011

With the development of electronic commerce, usability on a website is vital to customers and enterprises from ecommerce websites. However, many of these e-commerce applications still do not meet customers' usability requirements and the web pages need a better human computed interface. An evaluation of business to customer (B2C) websites in China was implemented according to the usability criterion. Two questionnaires were designed and verified to capture the evaluation index when customers operated the B2C websites. The fist on was used to choose the appropriate factors in questionnaire scale and the second one was used to evaluated the importance of the chosen factors. Finally, the usability indices were used to evaluate the characteristic of two main China B2C websites. The results obtained would help the designers of B2C electronic commerce to improve their websites. © 2011 Published by Elsevier Ltd.

Zhu W.,Zhangzhou Normal University | Wang S.,University of Electronic Science and Technology of China
Information Sciences | Year: 2013

Rough sets provide an efficient tool for attribute reduction and rule extraction. However, many important problems in rough set theory, including attribute reduction, are NP-hard and therefore the algorithms for solving them are usually greedy. As a generalization of linear independence in vector spaces, matroids have wide applications in diverse fields, particularly in greedy algorithm design. In this paper, we propose an integration of rough sets and matroids to exploit the advantages of both theories. Specifically, we present definitions of lower and upper rough matroids based on relations from the viewpoint of approximation operators. It is interesting that lower rough matroids based on partial orders coincide with poset matroids, which are a well-known generalization of matroids. A matroid is represented by the lower rough matroid based on both a partial order and an equivalence relation. Lower and upper rough matroids based on equivalence relations coincide with each other. Finally, we present some special types of examples of rough matroids from the viewpoints of approximations and graphs. These interesting results demonstrate the potential for the combination between rough sets and matroids. © 2013 Elsevier Inc. All rights reserved.

Christian M.,University of Minnesota | Qi Y.,University of Minnesota | Zhang Y.,University of Electronic Science and Technology of China | Voytas D.F.,University of Electronic Science and Technology of China
G3: Genes, Genomes, Genetics | Year: 2013

Custom TAL effector nucleases (TALENs) are increasingly used as reagents to manipulate genomes in vivo. Here, we used TALENs to modify the genome of the model plant, Arabidopsis thaliana. We engineered seven TALENs targeting five Arabidopsis genes, namely ADH1, TT4, MAPKKK1, DSK2B, and NATA2. In pooled seedlings expressing the TALENs, we observed somatic mutagenesis frequencies ranging from 2-15% at the intended targets for all seven TALENs. Somatic mutagenesis frequencies as high as 41-73% were observed in individual transgenic plant lines expressing the TALENs. Additionally, a TALEN pair targeting a tandemly duplicated gene induced a 4.4-kb deletion in somatic cells. For the most active TALEN pairs, namely those targeting ADH1 and NATA2, we found that TALEN-induced mutations were transmitted to the next generation at frequencies of 1.5-12%. Our work demonstrates that TALENs are useful reagents for achieving targeted mutagenesis in this important plant model. © 2013 Christian et al.

Zhang W.,University of Electronic Science and Technology of China | Poor H.V.,Princeton University
IEEE Transactions on Information Theory | Year: 2011

The problem of detecting a wide-sense stationary Gaussian signal process embedded in white Gaussian noise, in which the power spectral density of the signal process exhibits uncertainty, is investigated. The performance of minimax robust detection is characterized by the exponential decay rate of the miss probability under a Neyman-Pearson criterion with a fixed false alarm probability, as the length of the observation interval grows without bound. A stochastic suppression condition is identified for the uncertainty set of spectral density functions, and it is established that, under the stochastic suppression condition, the resulting minimax problem possesses a saddle point, which is achievable by the likelihood ratio tests matched to a so-called suppressing power spectral density in the uncertainty set. No convexity condition on the uncertainty set is required to establish this result. © 2011 IEEE.

Wang J.,City University of Hong Kong | Qiao C.,State University of New York at Buffalo | Yu H.,University of Electronic Science and Technology of China
Proceedings - IEEE INFOCOM | Year: 2011

A major disruption may affect many network components and significantly lower the capacity of a network measured in terms of the maximum total flow among a set of source-destination pairs. Since only a subset of the failed components may be repaired at a time due to e.g., limited availability of repair resources, the network capacity can only be progressively increased over time by following a recovery process that involves multiple recovery stages. Different recovery processes will restore the failed components in different orders, and accordingly, result in different amount of network capacity increase after each stage. This paper aims to investigate how to optimally recover the network capacity progressively, or in other words, to determine the optimal recovery process, subject to limited available repair resources. We formulate the optimization problem, analyze its computational complexity, devise solution schemes, and conduct numerical experiments to evaluate the algorithms. The concept of progressive network recovery proposed in this paper represents a paradigm-shift in the field of resilient and survivable networking to handle large-scale failures, and will motivate a rich body of research in network design and other applications. © 2011 IEEE.

Lei Y.,Xi'an Jiaotong University | Lin J.,Xi'an Jiaotong University | Zuo M.J.,University of Electronic Science and Technology of China | Zuo M.J.,University of Alberta | He Z.,Xi'an Jiaotong University
Measurement: Journal of the International Measurement Confederation | Year: 2014

Planetary gearboxes significantly differ from fixed-axis gearboxes and exhibit unique behaviors, which invalidate fault diagnosis methods working well for fixed-axis gearboxes. Much work has been done for condition monitoring and fault diagnosis of fixed-axis gearboxes, while studies on planetary gearboxes are not that many. However, we still notice that a number of publications on condition monitoring and fault diagnosis of planetary gearboxes have appeared in academic journals, conference proceedings and technical reports. This paper aims to review and summarize these publications and provide comprehensive references for researchers interested in this topic. The structures of a planetary gearbox as well as a fixed-axis one are briefly introduced and contrasted. The unique behaviors and fault characteristics of planetary gearboxes are identified and analyzed. Investigations on condition monitoring and fault diagnosis of planetary gearboxes are summarized based on the adopted methodologies. Finally, open problems are discussed and potential research topics are pointed out. © 2013 Elsevier Ltd. All rights reserved.

Wang H.,University of Electronic Science and Technology of China | Wang H.,Anshun University | Huang T.-Z.,University of Electronic Science and Technology of China | Xu Z.,Xi'an Jiaotong University | Wang Y.,University of Electronic Science and Technology of China
Information Sciences | Year: 2014

In this paper, we propose an active contour model and its corresponding algorithms with detailed implementation for image segmentation. In the proposed model, the local and global region fitting energies are described by the combination of the local and global Gaussian distributions with different means and variances, respectively. In this combination, we increase a weighting coefficient by which we can adjust the ratio between the local and global region fitting energies. Then we present an algorithm for implementing the proposed model directly. Considering that, in practice, the selection of the weighting coefficient is troublesome, we present a modified algorithm in order to overcome this problem and increase the flexibility. By adaptively updating the weighting coefficient and the time step with the contour evolution, this algorithm is less sensitive to the initialization of the contour and can speed up the convergence rate. Besides, it is robust to the noise and can be used to extract the desired objects. Experiment results demonstrate that the proposed model and its algorithms are effective with application to both the synthetic and real-world images. © 2014 Published by Elsevier Inc.

Liang D.,University of Electronic Science and Technology of China | Liu D.,Southwest Jiaotong University
Information Sciences | Year: 2014

Decision-theoretic rough sets (DTRS) are a representative rough set model. The loss function is a pivotal ingredient of DTRS, which is associated with the decision maker's evaluation. Considering the value of loss function with the imprecise evaluation, interval-valued DTRS (IVDTRS) and its mechanism in this paper are explored. First, we construct a basic model of IVDTRS. The comparison between DTRS and IVDTRS is discussed. In the frame of IVDTRS, we then focus on deriving three-way decisions with the aid of two conventional methods, i.e., a certain ranking method and a degree of possibility ranking method, respectively. The certain ranking method converts an interval value into single and derives decision rules under a certain risk attitude of decision maker; the degree of possibility ranking method assumes the flexibility of interval and utilizes the preference between interval values. All the combinations and their prerequisites are summarized, in which we obtain two types of decision rules. Based on the above analysis, we further propose an optimization method for three-way decisions with IVDTRS, which is designed to minimize the overall uncertainty based on the Shannon entropy. We also compare these methods based on standard data sets. Finally, the criteria for choosing a suitable method to three-way decisions with IVDTRS are generated. These results can support decision making in the uncertain environment. © 2013 Elsevier Inc. All rights reserved.

Scheele D.,University of Bonn | Kendrick K.M.,University of Electronic Science and Technology of China | Khouri C.,University of Bonn | Kretzer E.,University of Bonn | And 6 more authors.
Neuropsychopharmacology | Year: 2014

Social communication through touch and mutual grooming can convey highly salient socio-emotional signals and has been shown to involve the neuropeptide oxytocin (OXT) in several species. Less is known about the modulatory influence of OXT on the neural and emotional responses to human interpersonal touch. The present randomized placebo (PLC)-controlled within-subject pharmaco-functional magnetic resonance imaging (fMRI) study was designed to test the hypothesis that a single intranasal dose of synthetic OXT (24 IU) would facilitate both neural and emotional responses to interpersonal touch in a context- (female vs male touch) and trait- (autistic trait load) specific manner. Specifically, the experimental rationale was to manipulate the reward value of interpersonal touch independent of the intensity and type of actual cutaneous stimulation administered. Thus, 40 heterosexual males believed that they were touched by either a man or a woman, although in fact an identical pattern of touch was always given by the same female experimenter blind to condition type. Our results show that OXT increased the perceived pleasantness of female, but not male touch, and associated neural responses in insula, precuneus, orbitofrontal, and pregenual anterior cingulate cortex. Moreover, the behavioral and neural effects of OXT were negatively correlated with autistic-like traits. Taken together, this is the first study to show that the perceived hedonic value of human heterosexual interpersonal touch is facilitated by OXT in men, but that its behavioral and neural effects in this context are blunted in individuals with autistic traits. © 2014 American College of Neuropsychopharmacology. All rights reserved.

Wu Z.,University of Electronic Science and Technology of China | Yu H.,University of Electronic Science and Technology of China | Chen C.W.,State University of New York at Buffalo
IEEE Signal Processing Letters | Year: 2010

Video frame resizing has received more and more research attention as contemporary video distributions need to deliver video to various receiving devices with different display resolutions. It is now becoming necessary for video distribution systems to be able to generate higher resolution video from lower resolution one for some end users. Current schemes in video up-sampling either only focused on improving visual quality with little or no improvement in objective quality or increasing the up-sampling accuracy by adaptively optimizing interpolation methods. Many such algorithms are typically quite complex and require substantial extra implementation efforts. In this letter, we propose a new hybrid DCT-Wiener-based interpolation scheme for video intra frame up-sampling without referencing the original high resolution video frames. This scheme takes full advantage of interpolation in both DCT domain and spatial domain and seamlessly integrates these two approaches to design an improved up-sampling filter. Experiments have been carried out to demonstrate that noticeable improvement in both objective and visual quality are obtained. With similar complexity, the proposed algorithm can achieve up to 4 dB gain in PSNR over fixed parameter Wiener filter-based interpolation, 4 dB gain over popular bicubic interpolation, and 1 dB gain over up-sampling scheme in DCT domain. © 2006 IEEE.

Wen R.,University of Electronic Science and Technology of China | Wen R.,University of Minnesota
Electronics Letters | Year: 2013

Two compact triple-band monopole antennas consisting of a singleloop resonator (SLR) fed with coplanar waveguide (CPW) and microstrip transmission lines, respectively, are proposed. The SLR exhibiting three resonances is used to achieve the three operating frequency bands ranging from 2.4 to 6 GHz. The proposed triple-band antennas exhibit very well eight-like radiation patterns and low cross-polarisations, which have potential applications for wireless communications. © The Institution of Engineering and Technology 2013.

Wang S.,University of Electronic Science and Technology of China | Zhu Q.,University of Electronic Science and Technology of China | Zhu W.,Zhangzhou Normal University | Min F.,Zhangzhou Normal University
Knowledge-Based Systems | Year: 2012

Rough sets are efficient for data pre-processing in data mining. However, some important problems such as attribute reduction in rough sets are NP-hard, and the algorithms to solve them are almost greedy ones. As a generalization of the linear independence in vector spaces, matroids provide well-established platforms for greedy algorithms. In this paper, we apply matroids to rough sets through an isomorphism from equivalence relations to 2-circuit matroids. First, a matroid is induced by an equivalence relation. Several equivalent characterizations of the independent sets of the induced matroid are obtained through rough sets. Second, an equivalence relation is induced by a matroid. The relationship between the above two inductions is studied. Third, an isomorphism from equivalence relations to 2-circuit matroids is established, which lays a sound foundation for studying rough sets using matroidal approaches. Finally, attribute reduction is equivalently formulated with rank functions and closure operators of matroids. These results show the potential for designing attribute reduction algorithms using matroidal approaches. © 2012 Elsevier B.V. All rights reserved.

Liu G.,Samsung | Liu G.,University of Electronic Science and Technology of China | Zhidkov S.V.,Samsung
IEEE Transactions on Broadcasting | Year: 2010

In this paper, we presents a novel synchronizer dealing with carrier frequency offset (CFO), sampling frequency offset (SFO), as well as frame timing offset (FTO) in TDS-OFDM receiver. The proposed schemes are based on tracking the output waveform of a composite PN-correlator (CPC), which provides sufficient correlative gains to detect its peaks even in the presence of large CFOs. From the correlation peaks, we can extract useful information for estimating the synchronization offsets. CFO is recovered by a multi-stage CPC scheme, of which the parameters are adjustable for meeting the system's demands on the tracking range and accuracy. According to the inter-frame variations of correlation waveform, we estimate SFO for a large scale and correct SFO through an interpolator. Meanwhile, frame timing is investigated in this paper, and the analysis indicates a very fast and robust timing scheme is possible for TDS-OFDM receiver. The developed synchronizer is quite robust against a large CFO even in very adverse fading channels, and it is shown by computer simulation that the residual synchronization error has little effect on the performance of TDS-OFDM receiver. © 2006 IEEE.

Zhang W.,University of Electronic Science and Technology of China | Poor H.V.,Princeton University
IEEE Transactions on Information Theory | Year: 2013

With a finite number of samples drawn from one of two possible distributions sequentially revealed, an opportunistic detection rule is proposed, which possibly makes an early decision in favor of the alternative hypothesis, while always deferring the decision of the null hypothesis until collecting all the samples. Properties of this opportunistic detection rule are discussed and its key asymptotic behavior in the large sample size limit is established. Specifically, a Chernoff-Stein lemma type of characterization of the exponential decay rate of the miss probability under the Neyman-Pearson criterion is established, and consequently, a performance metric of asymptotic exponential efficiency loss is proposed and discussed, which is exactly the ratio between the Kullback-Leibler distance and the Chernoff information of the two hypotheses. Analytical results are corroborated by numerical experiments. © 1963-2012 IEEE.

Meng F.,University of Electronic Science and Technology of China | Ishida H.,Case Western Reserve University | Liu X.,University of Electronic Science and Technology of China

A high degree of functionalization on the surface of graphene oxide (GO-BZ) by benzoxazine is achieved via click chemistry. The modified GO-BZ is used to prepare single layer polymer-grafted 2D nano-hybrids. The GO-BZ exhibits good solubility and lower polymerization temperature in benzoxazine resins and imparts higher thermal stability to the corresponding GO. © 2014 The Royal Society of Chemistry.

Teng Y.,University of Electronic Science and Technology of China | Wang J.,University of New South Wales
GPS Solutions | Year: 2015

With the future global navigation satellite system (GNSS), the multi-GNSS constellations, which are composed of various single systems, will be the main navigation method in future. For the multi-GNSS constellations, the geometric dilution of precision (GDOP) is an important parameter used for satellite selection and the evaluation of positioning accuracy. However, the calculation of GDOP is a time-consuming and power-consuming task. Using Schur complement, we present a closed-form formula to calculate GDOP for multi-GNSS constellations. The formula can be applied to multi-GNSS constellations that include two, three or four different single systems. Furthermore, a closed-form formula for the case of exactly five satellites is also derived. Compared with the conventional numerical methods, the formula can reduce the amounts of multiplication and addition effectively. Numerical experiments validate the effectiveness and feasibility of the closed-form formula. © 2015 Springer-Verlag Berlin Heidelberg

Cheng J.,University of Electronic Science and Technology of China | Zhu H.,University of Electronic Science and Technology of China | Zhong S.,University of Electronic Science and Technology of China | Zeng Y.,University of Electronic Science and Technology of China | Dong X.,Xihua University
ISA Transactions | Year: 2013

This paper is concerned with the problem of finite-time H∞ control for a class of Markovian jump systems with mode-dependent time-varying delays via new Lyapunov functionals. In order to reduce conservatism, a new Lyapunov-Krasovskii functional is constructed. Based on the derived condition, the reliable H∞ control problem is solved, and the system trajectory stays within a prescribed bound during a specified time interval. Finally, numerical examples are given to demonstrate the proposed approach is more effective than some existing ones.© 2013 Published by Elsevier Ltd. All rights reserved.

Zhang T.,University of Electronic Science and Technology of China | Xia N.-G.,University of Delaware
IEEE Transactions on Geoscience and Remote Sensing | Year: 2015

The existing linear-frequency-modulated (or step frequency) and random noise synthetic aperture radar (SAR) systems may correspond to the frequency-hopping and direct-sequence spread spectrum systems in the past second- and third-generation wireless communications. Similar to the current and future wireless communications generations, in this paper, we propose the orthogonal frequency-division multiplexing (OFDM) SAR imaging, where a sufficient cyclic prefix (CP) is added to each OFDM pulse. The sufficient CP insertion converts an intersymbol interference (ISI) channel from multipaths into multiple ISI-free subchannels as the key in a wireless communications system, and analogously, it provides an inter-range-cell interference (IRCI)-free (high range resolution) SAR image in a SAR system. The sufficient CP insertion along with our newly proposed SAR imaging algorithm, particularly for the OFDM signals, also differentiates this paper from all the existing studies in the literature on OFDM radar signal processing. Simulation results are presented to illustrate the high-range-resolution performance of our proposed CP-based OFDM SAR imaging algorithm. © 2014 IEEE.

Xiao-Feng P.,University of Electronic Science and Technology of China | Xiao-Feng P.,CAS Shenyang International Center for Materials Physics
Progress in Biophysics and Molecular Biology | Year: 2012

A new theory of bio-energy transport along protein molecules in living systems, where the energy is released by hydrolysis of adenosine triphosphate (ATP), is proposed based on some physical and biological reasons. In the new theory, the Davydov's Hamiltonian and wave function of the systems are simultaneously modified and extended. A new interaction has been added into Davydov's Hamiltonian. The wave function of the excitation state of single particles for the excitons in the Davydov model is replaced by a new wave function of two-quanta quasicoherent state. In such a case, the bio-energy is transported by the new soliton, which differs from the Davydov's soliton. The soliton is formed through self- trapping of two excitons interacting amino acid residues. The exciton is generated by vibrations of amide-I (CO stretching) arising from the energy of hydrolysis of ATP. The properties of the new soliton are extensively studied by analytical method and its lifetime is calculated using the nonlinear quantum perturbation theory and a wide ranges of parameter values relevant to protein molecules. The lifetime of the new soliton at the biological temperature 300K is enough large and belongs to the order of 10-10s, or τ/τ0≥700, in which the soliton can transports over several hundreds amino acid residues. These studied results show clearly that the new soliton is thermally stable and has so larger lifetime that it can play an important role in biological processes. Thus the new model is a candidate of the bio-energy transport mechanism in protein molecules. In the meanwhile, the influences of structure nonuniformity in protein molecules and temperature of the systems on the states and properties of the soliton transport of bio-energy are numerically simulated and studied by the fourth-order Runge-Kutta method. The structure nonuniformity arises from the disorder distributions of masses of amino acid residues, side groups and impurities, which results also in the fluctuations of the spring constant of protein molecules, dipole-dipole interaction between the neighboring amides, exciton-phonon (vibration of amino acids)interaction, chain-chain interaction among the three channels and ground state energy of the systems. We investigated the behaviors and states of the new solitons in a single protein molecular chain and α-Helix protein molecules with three channels under influences of the structure nonuniformity. We prove first that the bio-energy is transported by a soliton, which can move without dispersion, retaining its shape, velocity and energy in a uniform and periodic protein molecule. When the structure nonuniformity exists, although the fluctuations of the spring constant, dipole-dipole interaction constant, exciton-phonon coupling constant and ground state energy and the nonuniformity distributions of masses of amino acid residues can change the states and properties of motion of new soliton, they are still quite stable and very robust against these structure nonuniformities, i.e., even there are a larger structure nonuniformity in the protein molecules, the new solitons cannot be still dispersed. If the effects of thermal perturbation of medium on the soliton in nonuniform proteins is considered again, the new soliton can transport also over a larger spacing of 400 amino acids and has a longer time period of 300ps, it is still thermally stable up to 320K under the influence of the above structure nonuniformities. However, the new soliton disperses in the case of a higher temperature of 325K and in more large structure nonuniformity. Thus, we determine that the new soliton's lifetime and critical temperature are 300ps and 320K, respectively. These results are also consistent with analytical data obtained via quantum perturbed theory. For α-Helix protein molecules with three channels, the results obtained show that the structure nonuniformity and quantum fluctuation can change the states and features of the new solitons, for example, the amplitudes, energies and velocities of the new soliton are decreased, but the solitons have been not destroyed, they can still transport steadily along the molecular chains retaining energy and momentum. When the quantum fluctuations are larger, such as, structure disorders and quantum fluctuations of 0.67<αK<2, ΔW=±8%W-, ΔJ=±1%J-, Δ(χ1+χ2)=±3%(χ-1+χ-2) and ΔL=±1%L- and Δe{open}0=e{open}|βn|, e{open}=0.1meV, |βn|<0.5, the new soliton is still stable. Therefore, the new solitons are quite robust against these nonuniform effects. However, they will be dispersed or disrupted in cases of very large structure nonuniformity. When the influence of temperature on solitons is considered, we find that the new solitons can transport steadily over 333 amino acid residues in the case of a long time period of 120ps, in which the soliton can retain its shape and energy to travel forward along protein molecules after their mutual collision at the biological temperature of 300K. However, the soliton disperses in cases of higher temperatures 325K under action of a larger structure disorder. Thus, its critical temperature is about 320K. When the effects of structure nonuniformity andtemperature are considered simultaneously, then the new soliton has still high thermal stability andcan transport also along the protein molecular chains retaining its amplitude, energy and velocity, they will disperses in the larger fluctuations, for example, 0.67M-

Fan X.,University of Delaware | Wu J.,University of Delaware | Chen Y.,University of Delaware | Jerry M.J.,University of Delaware | And 2 more authors.
Nature Communications | Year: 2013

The spin-orbital interaction in heavy nonmagnetic metal/ferromagnetic metal bilayer systems has attracted great attention and exhibited promising potentials in magnetic logic devices, where the magnetization direction is controlled by passing an electric current. It is found that the spin-orbital interaction induces both an effective field and torque on the magnetization, which have been attributed to two different origins: the Rashba effect and the spin Hall effect. It requires quantitative analysis to distinguish the two mechanisms. Here we show sensitive spin-orbital effective field measurements up to 10 nm thick ferromagnetic layer and find the effective field rapidly diminishes with the increase of the ferromagnetic layer thickness. We further show that this effective field persists even with the insertion of a copper spacer. The nonlocal measurement suggests that the spin-orbital effective field does not rely on the heavy normal metal/ferromagnetic metal interface. © 2013 Macmillan Publishers Limited. All rights reserved.

He W.,University of Electronic Science and Technology of China | Goodenough J.B.,University of Texas at Austin
Journal of Power Sources | Year: 2014

Mass transport is of paramount importance to the electrochemical performance of fuel cells. The high performance of fuel cells requires a large diffusion coefficient, i.e. the diffusivity, of the gas transport in electrodes and efficient gas diffusion can lead to large limiting currents and controlled concentration polarization. Recently-designed electrochemical devices allow for the direct evaluation of gas diffusivity in fuel cells. To realize these devices, a gas pump and an oxygen sensor are typically attached to two different spots of the inside wall of an electrolyte tube, which inevitably induces the uncertainty in measurement temperature. To eliminate temperature uncertainty in the diffusivity measurement, an electrochemical device with a multifunctional sensor is designed in this report. Quantitative analysis shows that temperature uncertainty can indeed induce substantial evaluation errors of gas diffusivity, limiting current density and concentration polarization, which in turn verifies the necessity of the multifunctional sensor device for the accurate diffusivity measurement in fuel cells. © 2013 Elsevier B.V. All rights reserved.

Feng D.,University of Electronic Science and Technology of China | Jiang C.,University of Delaware | Lim G.,University of Delaware | Cimini Jr. L.J.,University of Delaware | And 2 more authors.
IEEE Communications Surveys and Tutorials | Year: 2013

Reducing energy consumption in wireless communications has attracted increasing attention recently. Advanced physical layer techniques such as multiple-input multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM), cognitive radio, network coding, cooperative communication, etc.; new network architectures such as heterogeneous networks, distributed antennas, multi-hop cellulars, etc.; as well as radio and network resource management schemes such as various cross-layer optimization algorithms, dynamic power saving, multiple radio access technologies coordination, etc. have been proposed to address this issue. In this article, we overview these technologies and present the state-of-the-art on each aspect. Some challenges that need to be solved in the area are also described. © 1998-2012 IEEE.

Yang H.-X.,Fuzhou University | Tang M.,University of Electronic Science and Technology of China
Physica A: Statistical Mechanics and its Applications | Year: 2014

The design of routing strategies for networks of mobile nodes has received increasing attention in recent years. In this paper, we propose an adaptive routing strategy that incorporates geographical distance with local traffic information through a tunable parameter h. It is found that there exists an optimal value of h, leading to the maximum traffic throughput of the network. The optimal value of h decreases as the moving speed increases and increases as the communication radius increases. The dependence of the throughput on the moving speed and the communication radius is also studied. Our results show that for a wide range of the parameters, the throughput decreases as the moving speed increases. However, when the value of the parameter is set to be one, the maximum throughput is obtained at a moderate speed. Moreover, we find that the throughput increases with the communication radius.© 2014 Elsevier B.V. All rights reserved.

Li P.,University of Hong Kong | Li Y.,University of Electronic Science and Technology of China | Jiang L.J.,University of Hong Kong | Hu J.,University of Electronic Science and Technology of China
IEEE Transactions on Antennas and Propagation | Year: 2013

Conventional equivalent source reconstruction methods are only operating at a single frequency point each time. However, for wide-band radiators, their computation cost of the source reconstruction increases with the number of frequency points. In this communication, a wide-band equivalent source reconstruction method (WB-SRM) based on the Neville-type Stoer-Bulirsch (SB) algorithm is developed. Since the SB algorithm is a recursive tabular method, it can perform the interpolation over a broadband using a single rational function without any singularity issue. Supported by the adaptive frequency sampling (AFS) scheme, the number of required sampling data is significantly reduced, which leads to much better computational efficiency. During the AFS process, three fitting models (FM) are considered: two are 'triangle rules,' and another one is 'rhombus rule.' In this communication, a bisection searching strategy is performed. Furthermore, to achieve high-order accuracy, the Nyström method is implemented. Numerical examples are presented to validate the proposed WB-SRM and demonstrate its accuracy and applications. © 1963-2012 IEEE.

Pang X.-F.,University of Electronic Science and Technology of China | Pang X.-F.,CAS Shenyang International Center for Materials Physics
Physics of Life Reviews | Year: 2011

The bio-energy transport is a basic problem in life science and related to many biological processes. Therefore to establish the mechanism of bio-energy transport and its theory have an important significance. Based on different properties of structure of α-helical protein molecules some theories of bio-energy transport along the molecular chains have been proposed and established, where the energy is released by hydrolysis of adenosine triphosphate (ATP). A brief survey of past researches on different models and theories of bio-energy, including Davydov's, Takeno's, Yomosa's, Brown et al.'s, Schweitzer's, Cruzeiro-Hansson's, Forner's and Pang's models were first stated in this paper. Subsequently we studied and reviewed mainly and systematically the properties, thermal stability and lifetimes of the carriers (solitons) transporting the bio-energy at physiological temperature 300 K in Pang's and Davydov's theories. From these investigations we know that the carrier (soliton) of bio-energy transport in the α-helical protein molecules in Pang's model has a higher binding energy, higher thermal stability and larger lifetime at 300 K relative to those of Davydov's model, in which the lifetime of the new soliton at 300 K is enough large and belongs to the order of 10-10 s or τ/τ0≥700. Thus we can conclude that the soliton in Pang's model is exactly the carrier of the bio-energy transport, Pang's theory is appropriate to α-helical protein molecules. © 2011 Elsevier B.V.

Han H.,University of Electronic Science and Technology of China | Wang H.-J.,University of Electronic Science and Technology of China | Dong X.,Xihua University
Energy Procedia | Year: 2011

Failure of transformer is very complex, dissolved Gas in Oil Analysis (DGA) is presently the easier and simpler way for fault diagnosis of oil-immersed transformers. The correct selection of features of dissolved gas data can improve efficiency of transformer fault diagnosis. SVM is more effective than traditional methematic model to discribe the type of fault of transformer. As for the problem of difficulty of determining parameters in SVM applications, genetic algorithm (GA) was used to select SVM parameters. The test results show that this GA-SVM model is effective to detect failure of transformer. © 2011 Published by Elsevier Ltd.

Lin P.,University of Electronic Science and Technology of China | Qin K.,University of Electronic Science and Technology of China | Li Z.,Beijing Institute of Technology | Ren W.,Utah State University
Systems and Control Letters | Year: 2011

This paper addresses collective rotating motions of second-order multi-agent systems in three-dimensional space (3D). Two distributed control protocols are proposed and sufficient conditions are derived under which all agents rotate around a common point with a specified formation structure. Simulation results are provided to illustrate the effectiveness of the theoretical results. © 2011 Elsevier B.V. All rights reserved.

Liu T.,Western Michigan University | Wang B.,University of Electronic Science and Technology of China | Choi D.S.,NASA
Physics of Fluids | Year: 2012

The flow structures of Jupiter's Great Red Spot (GRS) are studied based on a high-resolution velocity field extracted from the Galileo 1996 cloud images of the GRS by using the physics-based optical flow method. The mean transverse velocity profile across the anti-cyclonic near-elliptical collar of the GRS is obtained. The flow structures in the relatively quiescent inner region enclosed by the high-speed collar are revealed at a coarse-grained level. The cyclonic source node in the inner region is identified that is directly associated with the observed cyclonic rotation near the center of the GRSits significance in the maintenance of the GRS is explored by using a topological constraint. © 2012 American Institute of Physics.

Gao S.S.,University of Hong Kong | Gao S.S.,University of Electronic Science and Technology of China | Sun S.,University of Electronic Science and Technology of China | Xiao S.,University of Electronic Science and Technology of China
IEEE Microwave and Wireless Components Letters | Year: 2013

A simple stub-loaded ring resonator is presented as a novel wideband bandpass power divider with good in-band responses and out-of-band harmonic suppression. The first two resonances of the ring resonator are excited and employed to construct a wideband passband. By adjusting the length of loaded open stubs, four transmission zeros can be generated in the lower and upper stopbands. After installing three coupled-line sections at one input port and two output ports along the ring, additional two in-band poles and one upper-stopband transmission zero are further introduced. Subsequently, total five transmission zeros are utilized to improve the passband selectivity and suppress the high-order harmonic. In addition, a single resistor is properly placed between two output ports to ensure the isolation. Finally, a prototype power divider is fabricated and verified experimentally with attractive bandpass features. © 2001-2012 IEEE.

Cui G.,University of Electronic Science and Technology of China | Demaio A.,University of Naples Federico II | Piezzo M.,University of Naples Federico II
IEEE Transactions on Aerospace and Electronic Systems | Year: 2013

We deal with the performance prediction of the incoherent radar receiver in the presence of arbitrary correlated, possibly nonidentically-distributed target backscattered echoes. The problem is of interest in some common scenarios that account for frequency agility, and polarization, as well as for spatial diversity. We develop analytic expressions for the detection probability in terms of function series, assuming that a generalized Swerling-chi distribution models the first order probability density function (pdf) of the target amplitude. Moreover, we study the speed of convergence of the resulting series and assess the impact on the detection performance of both the correlation and the nonidentical distribution of the target returns. © 1965-2011 IEEE.

Liu F.,University of Electronic Science and Technology of China | Liu F.,University of North Carolina at Chapel Hill | Wee C.-Y.,University of North Carolina at Chapel Hill | Chen H.,University of Electronic Science and Technology of China | And 2 more authors.
NeuroImage | Year: 2014

Previous studies have demonstrated that the use of integrated information from multi-modalities could significantly improve diagnosis of Alzheimer's Disease (AD). However, feature selection, which is one of the most important steps in classification, is typically performed separately for each modality, which ignores the potentially strong inter-modality relationship within each subject. Recent emergence of multi-task learning approach makes the joint feature selection from different modalities possible. However, joint feature selection may unfortunately overlook different yet complementary information conveyed by different modalities. We propose a novel multi-task feature selection method to preserve the complementary inter-modality information. Specifically, we treat feature selection from each modality as a separate task and further impose a constraint for preserving the inter-modality relationship, besides separately enforcing the sparseness of the selected features from each modality. After feature selection, a multi-kernel support vector machine (SVM) is further used to integrate the selected features from each modality for classification. Our method is evaluated using the baseline PET and MRI images of subjects obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Our method achieves a good performance, with an accuracy of 94.37% and an area under the ROC curve (AUC) of 0.9724 for AD identification, and also an accuracy of 78.80% and an AUC of 0.8284 for mild cognitive impairment (MCI) identification. Moreover, the proposed method achieves an accuracy of 67.83% and an AUC of 0.6957 for separating between MCI converters and MCI non-converters (to AD). These performances demonstrate the superiority of the proposed method over the state-of-the-art classification methods. © 2013 Elsevier Inc.

Zhang J.,University of Electronic Science and Technology of China | Yang H.-C.,University of Electronic Science and Technology of China | Yang D.,University of Electronic Science and Technology of China
IEEE Antennas and Wireless Propagation Letters | Year: 2012

A novel circularly polarized (CP) antenna with 1357-1997 MHz impedance bandwidth, 8 dB high gain, 3-dB axial-ratio bandwidth (ARBW) of 12.9% and ± 45° half-power beamwidth (HPBW) is proposed. Compared to other reported Inmarsat antennas, the proposed antenna possesses much higher gain and larger CP bandwidth and is more suitable for high-latitude satellite communication systems. © 2012 IEEE.

Xiang Y.,University of Electronic Science and Technology of China | Levitin G.,Israel Electric
IEEE Transactions on Reliability | Year: 2012

This paper proposes a new model that generalizes the linear multi-state sliding window system. In this model, the system consists of n linearly ordered multi-state elements. Each element can have different states spanning from complete failure up to perfectly functioning. A performance rate is associated with each state. The system fails if the gap between any pair of groups of r consecutive elements having the cumulative performance lower than a minimum allowable level W is less than m groups of r consecutive elements. An algorithm for system reliability evaluation is suggested which is based on an extended universal moment generating function. Examples of evaluating system reliability and elements' reliability importance indices are presented. © 2012 IEEE.

Zhang C.,University of Michigan | Zhao D.,University of Michigan | Gu D.,University of Michigan | Gu D.,University of Electronic Science and Technology of China | And 4 more authors.

An ultrathin, smooth, and low-loss Ag film without a wetting layer is achieved by co-depositing a small amount of Al into Ag. The film can be as thin as 6 nm, with a roughness below 1 nm and excellent mechanical flexibility. Organic photovoltaics that use these thin films as transparent electrode show superior efficiency to their indium tin oxide (ITO) counterparts because of improved photon management. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zang Y.,University of Washington | Li C.-Z.,University of Washington | Chueh C.-C.,University of Washington | Williams S.T.,University of Washington | And 4 more authors.

High-performance non-fullerene OSCs with PCEs of up to ca. 6.0% are demonstrated based on PBDTT-F-TT polymer and a molecular di-PBI acceptor through comprehensive molecular, interfacial, and device engineering. Impressive PCEs can also be retained in devices with relatively thick BHJ layer and processed through non-halogenated solvents, indicating these high-performance non-fullerene OSCs are promising for large-area printing applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hu J.,University of Electronic Science and Technology of China | Chen G.,City University of Hong Kong | Li H.-X.,City University of Hong Kong
Kybernetika | Year: 2011

As embedded microprocessors are applied widerly to multi-agent systems, control scheduling and time-delay problems arose in the case of limited energy and computational ability. It has been shown that the event-triggered actuation strategy is an effective methodology for designing distributed control of multi-agent systems with limited computational resources. In this paper, a tracking control problem of leader-follower multi-agent systems with/without communication delays is formulated and a distributed dynamic tracking control is designed by employing event-triggered technique. Then, the input-to-state stability of the closed-loop multi-agent system with directed interconnections is analyzed. Finally, a numerical example is given to validate the proposed control.

He B.,University of Electronic Science and Technology of China
Advanced Materials Research | Year: 2014

Low-power wireless sensor networks(WSNs) design involves all aspects of research in wireless sensor networks. As energy is limited in wireless sensor networks, how to effectively manage and use energy of WSNs, and how to maximize the reduction of power consumption in WSNs and extend the lifetime of WSNs become a key problem faced by wireless sensor networks. Aimed at these problems, a low-power clustering routing algorithm based on load-balanced is proposed. The algorithm introduced an energy load factor to reduce the power consumption of WSNs. The simulation results show that the low-power routing algorithm can effectively reduce power consumption of networks and extend the lifetime of networks. © (2014) Trans Tech Publications, Switzerland.

Yu L.,University of Electronic Science and Technology of China | Li H.,University of Electronic Science and Technology of China | Li W.,University of Electronic Science and Technology of China
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2014

Wireless video broadcast/multicast and mobile video communication pose a challenge to the conventional video transmission scheme (which consists of separate digital source coding and digital channel coding). The reason is that the separate coding scheme is based on nonscalable coding design, and this unavoidably leads to cliff effect as well as limits the ability to support multiple users with diverse channel conditions. In this paper, we propose a novel wireless scalable video coding (WSVC) framework. Specifically, we present a hybrid digital-analog (HDA) joint source-channel coding (JSCC) scheme that integrates the advantages of digital coding and analog coding. Moreover, the proposed JSCC is able to broadcast one video with different resolutions to fit various devices with different display resolutions. Compared to most state-of-the-art video delivery methods, it avoids the staircase effect and realizes continuous quality scalability (CQS) on condition that the channel quality is within the expected range, and it has strong adaptability to channel variation with higher coding efficiency and better fairness among all receivers. Therefore, it is very suitable for wireless video broadcast/multicast transmission and mobile video applications. The experimental results show that for broadcasting/multicasting the videos with CIF and QCIF resolutions the proposed WSVC 1) outperforms SoftCast (which is a new analog scheme) average 0.60∼5.90 dB and 3.39∼9.97 dB respectively, 2) outperforms SVC+HM (which combines H.264/SVC codec and hierarchical modulation technique) average 3.87∼9.13 dB and 0.27∼10.47 dB respectively, and 3) outperforms DCast (which is an up-to-date video delivery scheme) about 0.2∼3.3 dB for the video with CIF resolution. The experimental results verify the effectiveness of our proposed WSVC framework. © 2014 IEEE.

Gong Y.,University of Electronic Science and Technology of China | Zhao T.,University of Electronic Science and Technology of China | Rao Y.-J.,University of Electronic Science and Technology of China | Wu Y.,University of Electronic Science and Technology of China
IEEE Photonics Technology Letters | Year: 2011

A fiber-optic curvature sensor based on the single-modemultimodesingle-mode (SMS) fiber structure is developed. Several notches in the transmitted spectrum of the SMS fiber structure are generated due to the multimode interference effect. The dependence of the wavelength shifts and intensity changes of three transmission notches on the applied curvature are different from each other. The maximum sensitivities of wavelength-curvature and intensity-curvature relationships are - 10.38 nm/m-1 and - 130.37 dB/m-1, respectively. By properly choosing to measure wavelength shifts or intensity changes, high sensitivity measurement of curvature over a large scale can be obtained. The wavelength of the second notch is insensitive to the curvature change, offering the possibility for simultaneous measurement of curvature and other parameters such as temperature or strain. © 2011 IEEE.

Li J.,University of Electronic Science and Technology of China | Xu J.,University of Sichuan
Information Sciences | Year: 2013

This paper addresses the multi-objective portfolio selection model with fuzzy random returns for investors by studying three criteria: return, risk and liquidity. In addition, securities historical data, experts' opinions and judgements and investors' different attitudes are considered in the portfolio selection process, such that the investor's individual preference is reflected by an optimistic-pessimistic parameter λ. To avoid the difficulty of evaluating a large set of efficient solutions and to ensure the selection of the best solution, a compromise approach-based genetic algorithm has been designed to solve the proposed model. In addition, a numerical example is presented to illustrate the proposed algorithm. © 2012 Elsevier Inc. All rights reserved.

Xiong H.,University of Electronic Science and Technology of China | Li F.,University of Electronic Science and Technology of China | Qin Z.,University of Electronic Science and Technology of China
Information Sciences | Year: 2013

Threshold signature is an extension of the standard signature, in which several signers may be required to cooperatively sign messages for sharing the responsibility and authority. Certificateless cryptography eliminates the need of certificates in the Public Key Infrastructure and solves the inherent key-escrow problem in the Identity-based (ID-based) cryptography. In this paper, we propose a certificateless threshold signature scheme with concrete implementation which is provably secure in the standard model. Furthermore, this scheme is proven secure against the malicious-but-passive KGC attack. To the best of author's knowledge, this is the first construction of certificateless threshold signature scheme that does not rely on random oracle or ideal ciphers. © 2013 Elsevier Inc. All rights reserved.

Wei S.,University of Electronic Science and Technology of China | Hong Q.,University of Electronic Science and Technology of China | Hou M.,University of Electronic Science and Technology of China
Neurocomputing | Year: 2011

PCNN is a novel neural network model to simulate the synchronous phenomenon in the visual cortex system of the mammals. It has been widely used in the field of image processing and pattern recognition. However, there are still some limitations when it is applied to solve image processing problems, such as trial-and-error parameter settings and manually selection of the final results. This paper studies a simple model of PCNN(S-PCNN) and applies it to image segmentation. The main contributions of this paper are: (1) A new method based on the simplified model of PCNN is proposed to segment the images automatically. (2) The parameter settings are studied to ensure that the threshold decay of S-PCNN would be adaptively adjusted according to the overall characteristics of the image. (3) Based on the time series in S-PCNN, a simple selection criteria for the final results is presented to promote efficiency of the proposed method. (4) Simulations are carried out to illustrate the performance of the proposed method. © 2011 Elsevier B.V.

Xing L.,University of Electronic Science and Technology of China | Xing L.,University of Massachusetts Dartmouth | Amari S.V.,Parametric Technology (PTC) | Wang C.,University of Massachusetts Dartmouth
Reliability Engineering and System Safety | Year: 2012

In this paper, an efficient method is proposed for the exact reliability evaluation of k-out-of-n systems with identical components subject to phased-mission requirements and imperfect fault coverage. The system involves multiple, consecutive, and non-overlapping phases of operation, where the k values and failure time distributions of system components can change from phase to phase. The proposed method considers statistical dependencies of component states across phases as well as dynamics in system configuration and success criteria. It also considers the time-varying and phase-dependent failure distributions and associated cumulative damage effects for the system components. The proposed method is based on the total probability law, conditional probabilities and an efficient recursive formula to compute the overall mission reliability with the consideration of imperfect fault coverage. The main advantages of this method are that both its computational time and memory requirements are linear in terms of the system size, and it has no limitation on the type of time-to-failure distributions for the system components. Three examples are presented to illustrate the application and advantages of the proposed method. © 2012 Elsevier Ltd. All rights reserved.

Tian J.,University of Electronic Science and Technology of China | Zhong S.,University of Electronic Science and Technology of China
Neurocomputing | Year: 2011

In this paper, the problem of exponential stability criteria for neural networks with discrete and distributed time-varying delays are considered. By dividing the discrete delay interval into multiple segments and choosing a new class of Lyapunov functional which contains tripe-integral terms, some new delay-dependent stability criteria are derived in terms of linear matrix inequalities. The obtained criteria are less conservative because free-weighting matrices method and a convex optimization approach are considered. Finally, numerical examples are given to illustrate the effectiveness of the proposed method. © 2011 Elsevier B.V.

Song K.,University of Electronic Science and Technology of China | Mo Y.,University of Electronic Science and Technology of China | Xue Q.,City University of Hong Kong | Fan Y.,University of Electronic Science and Technology of China
IEEE Transactions on Industrial Electronics | Year: 2014

Two new wideband four-way out-of-phase slotline power dividers are proposed in this paper. The half-wavelength slotlines are employed to construct the presented compact power dividers. Based on the proposed power-dividing circuit, a four-way power divider is implemented with compact size and simple structure. To obtain high isolation among the four output ports and good output impedance matching, another four-way out-of-phase slotline power divider with improved isolation performance is designed by introducing an air-bridge resistor and two slotlines with isolation resistors. The simulated and measured results of the proposed power dividers demonstrate reasonable performance of impedance matching, insertion loss, amplitude balancing, and isolation among the output ports. © 1982-2012 IEEE.

Wang W.-Q.,University of Electronic Science and Technology of China | Wang W.-Q.,City University of Hong Kong | So H.C.,City University of Hong Kong
IEEE Transactions on Signal Processing | Year: 2014

Different from conventional phased-array, which provides only angle-dependent beampattern, frequency diverse array (FDA) employs a small frequency increment across the antenna elements and results in a range-angle-dependent beampattern. This beampattern offers a potential to localize the targets in two dimensions in terms of slant ranges and azimuth angles. However, it is difficult to obtain the target location information from a standard FDA radar due to the couplings in range and angle responses. In this paper, we propose a transmit subaperturing scheme on the FDA radar for range and angle estimation of targets. The essence is to divide the FDA elements into multiple subarrays and optimize the transmit beamspace matrix with the use of convex optimization. We also discuss several practical issues for designing the FDA radar system parameters. Since the subarrays offer decoupled range and angle responses, the targets can be located using the beamspace-based multiple signal classification algorithm. The range and angle estimation performance is evaluated by comparing with the Cramér-Rao lower bound. © 1991-2012 IEEE.

Song K.,City University of Hong Kong | Xue Q.,University of Electronic Science and Technology of China
Microwave and Optical Technology Letters | Year: 2010

A novel ultra-wideband (UWB) out-of-phase power divider with band-pass filtering response is presented. This power divider is constructed by introducing multilayer microstrip line-slotline coupling structure, which can not only divide/combine the power of microwave signals, but also reject unwanted frequency signals. To verify the features of this proposed out-of-phase power divider, one prototype divider is designed, fabricated, and measured. Good impedance matching, amplitude balance, and out-of-band rejection are obtained both by simulations and measurements.© 2010 Wiley Periodicals, Inc.

Yu J.,University of Electronic Science and Technology of China | Wang N.,University of Electronic Science and Technology of China | Zang Y.,University of Electronic Science and Technology of China | Jiang Y.,University of Electronic Science and Technology of China
Solar Energy Materials and Solar Cells | Year: 2011

The performance of organic photovoltaic (OPV) cells based on copper phthalocyanine (CuPc)/C60 heterojunction was investigated by focusing on the role of 1,3,5-tris(2-N-phenylbenzimidazolyl) benzene (TPBi) as a cathode buffer layer. The effect of the film thickness of TPBi layer on the electrical characteristics of the device was systematically studied. The interface between the acceptor and cathode was studied with the characterization of atomic force microscope. Optical field distribution inside the OPV cell was also simulated to gain insight into the mechanism responsible for TPBi used as an optical spacer. The results indicated that at an optimal film thickness, TPBi cathode buffer layer is essential to enhance device performance by forming improved interfacial contact without introducing more series resistance and current loss. © 2010 Elsevier B.V. All rights reserved.

Wu H.,University of Electronic Science and Technology of China | Wang Z.,University of Electronic Science and Technology of China | Fan M.,University of Electronic Science and Technology of China | Zhang L.,University of Electronic Science and Technology of China | And 2 more authors.
Optics Express | Year: 2015

In this paper, we thoroughly analyze the role of the point reflector's reflectivity in the performance of forward-pumped random fiber laser, in both the long- and short-cavity cases. The results show that the power performance is sensitive to the small reflection added on the pump side of the fiber end, whereas both the power distribution and threshold tend to be stable when the reflectivity reaches a relatively high level (>0.4). Moreover, for the short cavity case (e.g. 500m), the maximum achievable 1st-oder random lasing output can even increase when the reflectivity decreases from 0.9 to 0.01, due to the different lasing power distributions with different reflectivity values. This work reveals a new and unique property of random fiber lasers and provides insights into their design for the applications such as distributed amplification and high power sources. © 2015 Optical Society of America.

Xue C.,University of Electronic Science and Technology of China | Jiang N.,University of Electronic Science and Technology of China | Qiu K.,University of Electronic Science and Technology of China | Lv Y.,University of Electronic Science and Technology of China
Optics Express | Year: 2015

We propose and numerically demonstrate a new scheme for key distribution on the physical layer based on the chaos synchronization and physical random bit generation. In this scheme, two chaotic semiconductor lasers are commonly driven by a third semiconductor laser, their output chaotic signals are employed as the physical sources of the random bit generators (RBGs). Under symmetry operation scenario, the two RBGs are well synchronized and the random bits generated by them are used to generate identical secret keys for Alice and Bob by the way of a dynamic post-processing technology. The feasibility and security of the proposed scheme are investigated by testing the parameters mismatch tolerance and the sensitivity to the systematic noise. The numerical results indicate that the dynamic and unpredictable post-processing can provide a great enhancement for the security of the secret key distribution. The security of the proposed scheme mainly determined by the post-processing, not confidential source, which provides a new potential way for implementing high-speed secure secret key distribution. © 2015 Optical Society of America.

Zhou J.,Anhui Xinhua University | Zhou J.,South China Normal University | Yu W.-C.,South China Normal University | Gao Y.-M.,University of Electronic Science and Technology of China | Xue Z.-Y.,South China Normal University
Optics Express | Year: 2015

A cavity QED implementation of the non-adiabatic holonomic quantum computation in decoherence-free subspaces is proposed with nitrogen-vacancy centers coupled commonly to the whispering-gallery mode of a microsphere cavity, where a universal set of quantum gates can be realized on the qubits. In our implementation, with the assistant of the appropriate driving fields, the quantum evolution is insensitive to the cavity field state, which is only virtually excited. The implemented non-adiabatic holonomies, utilizing optical transitions in the Λ type of three-level configuration of the nitrogen-vacancy centers, can be used to construct a universal set of quantum gates on the encoded logical qubits. Therefore, our scheme opens up the possibility of realizing universal holonomic quantum computation with cavity assisted interaction on solid-state spins characterized by long coherence times. © 2015 Optical Society of America.

Zhang W.,University of Electronic Science and Technology of China
Journal of Applied Physics | Year: 2015

Electronic structure and magnetic properties of ZrFe2 in the cubic Laves phase are investigated by calculations based on density functional theory. The magnetic moment decreases with the increase of the hydrostatic pressure in an unusual way: Two-step magnetic collapse is predicted. The first one is a continuous change from 1.53-μB/Fe to 0.63-μB/Fe at about 3.6-GPa, and the other is from 0.25-μB/Fe to the nonmagnetic state at about 15-GPa in a first order manner under the local spin density approximation of the exchange correlation potential. A metastable state with intermediate spin moment about 0.15-μB/Fe may exist before that. We understand this process by the changes of density of states during it. The magnetic moment decreases under the pressure in the vicinity of the experimental lattice constant with d ln m / d p = - 0.038 GPa-1. The spontaneous volume magnetostriction is 3.6%, which is huge enough to find potential applications in magnetostriction actuators and sensors. We suggest that the Invar effect of this compound may be understood when considering the magnetic moment variation according to the magnetostrictive model of Invar. © 2015 AIP Publishing LLC.

Zhang Q.-M.,University of Electronic Science and Technology of China | Zeng A.,Hangzhou Normal University | Zeng A.,University of Fribourg | Shang M.-S.,Hangzhou Normal University
PLoS ONE | Year: 2013

Information overload is a serious problem in modern society and many solutions such as recommender system have been proposed to filter out irrelevant information. In the literature, researchers have been mainly dedicated to improving the recommendation performance (accuracy and diversity) of the algorithms while they have overlooked the influence of topology of the online user-object bipartite networks. In this paper, we find that some information provided by the bipartite networks is not only redundant but also misleading. With such "less can be more" feature, we design some algorithms to improve the recommendation performance by eliminating some links from the original networks. Moreover, we propose a hybrid method combining the time-aware and topology-aware link removal algorithms to extract the backbone which contains the essential information for the recommender systems. From the practical point of view, our method can improve the performance and reduce the computational time of the recommendation system, thus improving both of their effectiveness and efficiency. © 2013 Zhang et al.

Gong D.,University of Electronic Science and Technology of China | Hu J.,University of Electronic Science and Technology of China | Yao D.,University of Electronic Science and Technology of China
Psychophysiology | Year: 2012

With the two-choice go/no-go paradigm, we investigated whether timbre attribute can be transmitted as partial information from the stimulus identification stage to the response preparation stage in auditory tone processing. We manipulated two attributes of the stimulus: timbre (piano vs. violin) and acoustic intensity (soft vs. loud) to ensure an earlier processing of timbre than intensity. We associated the timbre attribute more with go trials. Results showed that lateralized readiness potentials (LRPs) were consistently elicited in no-go trials. This showed that the timbre attribute had been transmitted to the response preparation stage before the intensity attribute was processed in the stimuli identification stage. Such a result provides evidence for the continuous model and asynchronous discrete coding (ADC) model in information processing. We suggest that partial information can be transmitted in an auditory channel. © 2011 Society for Psychophysiological Research.

Zhang X.,University of Electronic Science and Technology of China | Wang H.,University of Electronic Science and Technology of China | Zhang Z.,University of Electronic Science and Technology of China
Computer Networks | Year: 2014

In this paper, we study the energy efficient problem of survivable IP over WDM networks. A novel "virtual link" energy model is presented. The energy model is abstrated ed from the power consumption value of commercial network devices. Based on the new two-layer energy-aware auxiliary graph, we propose the Energy-Efficient and Survivable Routing (E2SR) algorithm for IP over WDM networks against double-link failures. In contrast to prior green networking algorithms, the novelty of our proposed routing algorithm is mainly twofold: first, the energy-efficient virtual topology iterative mapping method; second, the energy-efficient spare resource sharing method. From the numerical results for two typical carrier networks, our proposed E2SR algorithm achieves obvious energy consumption reduction for IP over WDM networks when guaranteeing traffic survivability against double-link failures. © 2013 Elsevier B.V. All rights reserved.

Jin J.X.,University of Electronic Science and Technology of China | Zheng L.H.,University of Electronic Science and Technology of China
Superconductor Science and Technology | Year: 2011

Driving models of high temperature superconducting (HTS) linear synchronous motors (LSM) are studied and extracted from the HTS LSM technology developed to date. An HTS LSM using an HTS bulk magnet secondary has been developed and presented for technical verification. The HTS LSM drive combined with an HTS bulk-permanent magnet guideway (PMG) system for magnetic levitation results in running without sliding friction and having the functions of self-levitation and self-guidance without the need for a compulsory active control system. In this paper, driving models of the HTS LSMs are introduced with numerical analysis results. Different magnetization methods are applied to obtain the HTS bulk magnets, and the HTS magnetization characteristics using those methods are identified. Two types of PMGs are designed and prepared whose magnetic field distributions are simulated and practically tested for comparison. Comprehensive experiments have been conducted on the HTS LSM drive. The practical results obtained show that the HTS LSM developed has applicable thrust characteristics without the conventional friction, and a better practical performance can be achieved by using HTS bulk magnets having a higher trapped magnetic field. © 2011 IOP Publishing Ltd.

Wang Z.-G.,University of Electronic Science and Technology of China | Chen Y.-F.,University of Electronic Science and Technology of China | Li P.-J.,University of Electronic Science and Technology of China | Hao X.,University of Electronic Science and Technology of China | And 3 more authors.
ACS Nano | Year: 2011

For the first time, large-area CVD-grown graphene films transferred onto flexible PET substrates were used as transparent conductive electrodes in alternating current electroluminescence (ACEL) devices. The flexible ACEL device based on a single-layer graphene electrode has a turn-on voltage of 80 V; at 480 V (16 kHz), the luminance and luminous efficiency are 1140 cd/m2 and 5.0 lm/W, respectively. The turn-on voltage increases and the luminance decreases with increasing stacked layers of graphene, which means the single-layer graphene is the best optimal choice as the transparent conductive electrode. Furthermore, it demonstrates that the graphene-based ACEL device is highly flexible and can work very well even under a very large strain of 5.4%, suggesting great potential applications in flexible optoelectronics. © 2011 American Chemical Society.

Chang J.,University of Electronic Science and Technology of China
MATEC Web of Conferences | Year: 2016

The bistatic radar weak target detection problem is considered in this paper. An effective way to detect weak target is the long time integration. However, range migration (RM) will occur due to the high speed. Without knowing the target motion parameters, a long time integration algorithm for bistatic radar is proposed in this paper. Firstly, the algorithm utilizes second-order keystone transform (SKT) to remove range curvature. Then the quadratic phase term is compensated by the estimated acceleration. After that, SKT is used once more and the Doppler ambiguity phase term compensation is performed. At last, the target energy is integrated via FT. Simulations are provided to show the validity of the proposed algorithm in the end. © 2016 The Authors, published by EDP Sciences.

Li Y.,University of Electronic Science and Technology of China | Peng L.,Chengdu University of Information Technology
Journal of Magnetism and Magnetic Materials | Year: 2011

SmCo-based films were deposited on Si (1 0 0) substrates by the rf magnetron sputtering process. The growth conditions are improved for the films deposited on hot Si substrates without the annealing process. The dependence of crystal structure and intrinsic coercivity on substrate temperature is chiefly investigated. It is suggested that TbCu 7 type structural films can be obtained with enhanced in-plane magnetic properties with proper substrate temperature. © 2010 Elsevier B.V. All rights reserved.

Zhang C.,University of Electronic Science and Technology of China | Huang J.,University of Electronic Science and Technology of China | Chen C.,University of Electronic Science and Technology of China | Qiu K.,University of Electronic Science and Technology of China
Optics Express | Year: 2011

We propose and demonstrate a novel scheme, which enables alloptical virtual private network (VPN) and all-optical optical network units (ONUs) inter-communications in optical orthogonal frequency-division multiplexing-based passive optical network (OFDM-PON) system using the subcarrier bands allocation for the first time (to our knowledge). We consider the intra-VPN and inter-VPN communications which correspond to two different cases: VPN communication among ONUs in one group and in different groups. The proposed scheme can provide the enhanced security and a more flexible configuration for VPN users compared to the VPN in WDM-PON or TDM-PON systems. The all-optical VPN and inter-ONU communications at 10-Gbit/s with 16 quadrature amplitude modulation (16 QAM) for the proposed optical OFDM-PON system are demonstrated. These results verify that the proposed scheme is feasible. © 2011 Optical Society of America.

Rao Y.,University of Electronic Science and Technology of China | Chen L.,University of Electronic Science and Technology of China
Journal of Information Hiding and Multimedia Signal Processing | Year: 2012

Video enhancement is one of the most important and difficult components in video research. The aim of video enhancement is to improve the visual appearance of the video, or to provide a "better"transform representation for future automated video processing, such as analysis, detection, segmentation, recognition, surveillance, traffic, criminal justice systems. In this paper, we present an overview of video enhancement processing and analysis algorithms used in these applications. The existing techniques of video enhancement can be classified into two categories: Self-enhancement and Contextbased fusion enhancement. More specifically, we categorize processing methods based representative techniques of video enhancement. Thus, the contribution of the paper has fourfold: (1) to classify and review video enhancement processing algorithms, (2) to discuss the advantages and disadvantages of these algorithms, (3) according to this integrated consideration, attempt an evaluation of shortcomings and general needs in this field of active research, and (4) we will point out promising directions on research for video enhancement for future research. © 2012 ISSN 2073-4212.

Zhang W.L.,University of Electronic Science and Technology of China | Wang F.,University of Electronic Science and Technology of China | Rao Y.J.,University of Electronic Science and Technology of China | Jiang Y.,University of Electronic Science and Technology of China
Optics Express | Year: 2014

This paper proposes a novel concept of refractive index sensing taking advantage of a high-refractive-index-contrast optical Tamm plasmon (OTP) structure, i.e., an air/dielectric alternate-layered distributed Bragg reflector (DBR) coated with metal. In the reflection spectrum of the structure, a dip related to the formation of OTP appears. The wavelength and reflectivity of this dip are sensitive to variation of ambient refractive index, which provides a potential way to realize refractive index sensing with a large measuring range and high sensitivity. © 2014 Optical Society of America.

Xiang Y.,University of Electronic Science and Technology of China | Chen C.,University of Electronic Science and Technology of China | Zhang C.,University of Electronic Science and Technology of China | Qiu K.,University of Electronic Science and Technology of China
Optics Express | Year: 2013

In this paper, we propose and demonstrate a novel integrated radio-over-fiber passive optical network (RoF-PON) system for both wired and wireless access. By utilizing the polarization multiplexed four-wave mixing (FWM) effect in a semiconductor optical amplifier (SOA), scalable generation of multi-frequency millimeter-waves (MMWs) can be provided so as to assist the configuration of multi-frequency wireless access for the wire/wireless access integrated ROF-PON system. In order to obtain a better performance, the polarization multiplexed FWM effect is investigated in detail. Simulation results successfully verify the feasibility of our proposed scheme. © 2013 Optical Society of America.

Wang H.,University of Electronic Science and Technology of China | Wang J.,University of Electronic Science and Technology of China
Optics Express | Year: 2011

In this article, properties of solitons in a parity-time periodical lattices with a single-sited defect are investigated. Both of the negative and positive defects are considered. Linear stability analyses show that, when the defect is positive, in the semi-infinite gap, the solitons are always stable, while in the first gap, the solitons are unstable in most of their existence region except for those near the edge of the second band; when the defect is negative, in the semi-infinite gap, other than those near the edge of the first band, most solitons are stable, but in the first gap, all solitons are unstable. Such stability analyses are corroborated by numerical simulations. © 2011 Optical Society of America.

Zhu Y.Y.,University of Electronic Science and Technology of China | Zhang W.L.,University of Electronic Science and Technology of China | Jiang Y.,University of Electronic Science and Technology of China
IEEE Photonics Technology Letters | Year: 2013

A novel all-fiber tunable multi-wavelength Raman fiber laser is achieved in a 50 km single-mode fiber connected to a multi-channel wavelength tunable component (MCWTC), i.e., a F-P cavity combined with a long-period fiber gratings based Mach-Zehnder interferometer, that is obtained by micro-processing. Raman amplified Rayleigh scattering feedback provides the mechanism for random lasing that is split to equidistance wavelengths and tuned continuously from 1553.9 to 1565.4 nm by the MCWTC. © 1989-2012 IEEE.

Kou G.,University of Electronic Science and Technology of China | Ergu D.,Southwest University for Nationalities | Shi Y.,University of Electronic Science and Technology of China
Computers and Operations Research | Year: 2014

Most of the existing disaster assessment models are based on single method, such as expert system, or one of the multi-criteria decision making (MCDM) methods. This paper proposes an efficient disaster assessment expert system, which integrates fuzzy logic, survey questionnaire, Delphi method and MCDM methods. Two simulation experiments on typhoon and earthquake are introduced to validate the integrated expert system. The satisfaction degrees of the proposed model in both cases are 75% and 74.5%, respectively, which are close to the ideal rate (78%) of the proposed model. The experimental results show that the proposed expert system is not only efficient, fast and accurate, but also robust through self-adaptive study and has strong adaptability to different environments. © 2012 Elsevier Ltd.

Peng M.,University of Electronic Science and Technology of China | Peng Y.,University of Electronic Science and Technology of China | Chen H.,University of Electronic Science and Technology of China
Computers and Operations Research | Year: 2014

Post-seismic inventory and logistics planning under incomplete and fuzzy information is an important yet understudied area in supply chain risk management. The goal of this paper is to propose a system dynamics model to analyze the behaviors of disrupted disaster relief supply chain by simulating the uncertainties associated with predicting post-seismic road network and delayed information. The simulation results indicate: (1) information delay has different influences over the relief head-quarter (the upstream) and the disaster-affected areas (the downstream); and (2) the change of road conditions and shipment schedules have impact on the on-time transportation rate in supply chain management. Furthermore, this paper defined and tested supplies' replenishment solutions combined with three inventory planning strategies and four forecasting methods under different lead time uncertainties. The results show that: (1) a strategy that considers information from both the post-seismic management center and the affected areas can provide a better logistic plan than an one takes information from one side; (2) the smooth-the-trend forecasting method is suitable for inventory and logistic planning when the post-seismic situations are volatile, while the quick-response forecasting method has good performance in stable environments. In addition, this paper proposes decision tree to help decision makers choose the appropriate stocking strategies. © 2013 Elsevier Ltd.

Ergu D.,University of Electronic Science and Technology of China | Ergu D.,Southwest University for Nationalities | Kou G.,University of Electronic Science and Technology of China | Shi Y.,University of Nebraska at Omaha | And 2 more authors.
Computers and Operations Research | Year: 2014

In risk assessment and decision analysis, the analytical network process (ANP) is widely used to assess the key factors of risks and analyze the impacts and preferences of decision alternatives. There are lots of comparison matrices for a complicated risk assessment problem, but a decision has to be made rapidly in emergency cases. However, in the ANP, the reciprocal pairwise comparison matrices (RPCM) are more complicated and difficult than AHP. The consistency test and the inconsistent elements identification need to be simplified. In this paper, a maximum eigenvalue threshold is proposed as the consistency index for the ANP in risk assessment and decision analysis. The proposed threshold is mathematically equivalent to the consistency ratio (CR). To reduce the times of consistency test, a block diagonal matrix is introduced for the RPCM to conduct consistency tests simultaneously for all comparison matrices. Besides, the inconsistent elements can be identified and adjusted by an induced bias block diagonal comparison matrix. The effectiveness and the simplicity of the proposed maximum eigenvalue threshold consistency test method and the inconsistency identification and adjustment method are shown by two illustrative examples of emergent situations. © 2011 Elsevier Ltd.

Yang Y.,University of Electronic Science and Technology of China | Dong Y.,Soochow University of China | Zhao C.,Soochow University of China | Liu Y.-D.,University of Electronic Science and Technology of China | Cai Y.,Soochow University of China
Optics Express | Year: 2014

The spatial correlation singularity of a partially coherent vortex beam was demonstrated recently [Phys. Rev. Lett. 92, 143905 (2004)], and it was shown that the cross-correlation singularity disappears when the spatial coherence is high. In this paper, we demonstrate that the spatial autocorrelation function of a fully coherent beam in the far-field is equivalent to the Fourier transform of its intensity in the source plane. Our theoretical and experimental results show that, depending on both the radial and azimuthal mode indices (p, ?) of the incident light beam, the distribution of the far-field autocorrelation function displays a series of concentric, alternate bright and dark rings. This phenomenon may be used to determine the topological charge (the azimuthal index) of light beam with a nonzero radial index. © 2014 Optical Society of America.

Huang X.,University of Electronic Science and Technology of China | Feng M.,University of Electronic Science and Technology of China | Liu X.,University of Electronic Science and Technology of China

TiO2-MWCNT heterostructure nanotubes have been fabricated via a solvent-thermal method. Energy dispersive spectrometer and X-ray diffraction analysis revealed that the nanotubes are composed of C, Ti and O elements and TiO2 only contains the tetragonal anatase phase. SEM and TEM results show that most of the TiO2 bristles are vertically studded on the surface of the MWCNT. Subsequently, TiO2-MWCNT/polyarylene ether nitrile (PEN) composite films were prepared in order to investigate the effect of TiO2-MWCNT on the PEN matrix. SEM images exhibit that there is strong interfacial adhesion between the PEN matrix and fillers owing to the special bristle-like structure. Thermal analysis results show that TiO 2-MWCNT/PEN composite films possess excellent thermal properties endowed by the PEN matrix. Besides, the dielectric constant of the composite films increases from 4 to 109 at 100 Hz when the TiO2-MWCNT loading reaches 8 wt%. Rheology measurements reveal that there is an obvious difference between the rheological percolation threshold and the electrical percolation threshold. © 2014 The Royal Society of Chemistry.

Yi X.,University of Electronic Science and Technology of China | Qiu K.,University of Electronic Science and Technology of China
Optics Express | Year: 2011

Coherent optical OFDM systems employ DAC at the transmitters and ADC at the receivers. The sample frequencies of DAC and ADC in such systems need to be synchronized, especially in the context of high-speed transmissions. This paper presents a channel model including the effect of the sample frequency offset, which adds an additional phase shift proportional to the subcarrier index. The sample frequency offset monitoring and the compensation method are discussed and verified in experiment. It is expected that the synchronization can be achieved by feeding the monitoring result back to the receiver oscillator. © 2011 Optical Society of America.

Li F.,University of Electronic Science and Technology of China | Ye M.,University of Electronic Science and Technology of China | Chen X.,Chongqing Technology and Business University
International Journal of Approximate Reasoning | Year: 2014

Rough c-means algorithm has gained increasing attention in recent years. However, the assignment scheme of Rough c-means algorithm does not incorporate any information about the neighbors of the data point to be assigned and may cause undesirable solutions in practice. This paper proposes an extended Rough c-means clustering algorithm based on the concepts of decision-theoretic Rough Sets model. In the risk calculation, a new kind of loss function is utilized to capture the loss information of the neighbors. The assignment scheme of the present multi-category decision-theoretic Rough Sets model is also adjusted to deal with the potentially high computational cost. Experimental results are provided to validate the effectiveness of the proposed approach. © 2013 Elsevier Inc. All rights reserved.

Zhang N.,University of Electronic Science and Technology of China | Zhou P.,University of Electronic Science and Technology of China | Cheng D.,University of Electronic Science and Technology of China | Weng X.,University of Electronic Science and Technology of China | And 2 more authors.
Optics Letters | Year: 2013

We present the simulation, fabrication, and characterization of a dual-band metamaterial absorber in the midinfrared regime. Two pairs of circular-patterned metal-dielectric stacks are employed to excite the dual-band absorption peaks. Dielectric characteristics of the dielectric spacing layer determine energy dissipation in each resonant stack, i.e., dielectric or ohmic loss. By controlling material parameters, both two mechanisms are introduced into our structure. Up to 98% absorption is obtained at 9.03 and 13.32 μm in the simulation, which is in reasonable agreement with experimental results. The proposed structure holds promise for various applications, e.g., thermal radiation modulators and multicolor infrared focal plane arrays. © 2013 Optical Society of America.

Wang Z.,University of Electronic Science and Technology of China | Wu H.,University of Electronic Science and Technology of China | Fan M.,University of Electronic Science and Technology of China | Rao Y.,University of Electronic Science and Technology of China | And 2 more authors.
Optics Express | Year: 2013

Third-order random lasing operating in 1670nm spectral band is experimentally demonstrated for the first time to the best of our knowledge, with only 2.45W pump threshold. The lasing cavity is formed by G.652 fiber and fiber loop mirrors (FLMs), while the former acts as the distributed reflector and the latter acts as the point reflector. The G.652 fiber and the FLMs are connected via a multi-band wavelength-divisionmultiplexer, which ensures each of the three Raman Stokes components generated in the long fiber is routed to one FLM and then reflected back with minimum loss. Unlike existing half-open random lasing cavities using fiber Bragg gratings, the reflection bandwidth of FLMs is wide enough to preserve the intrinsic spectral features of each lasing bands, providing a valuable platform to study the mechanism of high-order random lasing in fibers. Also, the reflection efficiency can be treated as an invariant as the pump power grows, significantly reducing the threshold of high-order random lasing. The stationary model is used to calculate the output power, and the results fit the experimental data well. © 2013 Optical Society of America.

Li X.D.,Nanyang Technological University | Chen T.P.,Nanyang Technological University | Liu Y.,University of Electronic Science and Technology of China | Leong K.C.,Globalfoundries
Optics Express | Year: 2014

The contributions of localized surface plasmon resonance (LSPR) and Drude (free electrons) absorption to the complex dielectric function of ultrathin Au films were investigated with spectroscopic ellipsometry. When the Au film thickness is thinner than ∼10 nm, Au nanoparticles (NPs) are formed as a result of the discontinuity in the films, leading to the emergence of LSPR of Au NPs; and the LSPR exhibits a splitting when the films thinner than ∼8 nm, which could be attributed to the near-field coupling of the Au NPs and/or the inhomogeneous polarizations of the Au NPs. On the other hand, the delocalization of electrons in Au NPs due to the aggregation of Au NPs in a thicker film leads to an increase in the free-electron absorption and a suppression of the LSPR. © 2014 Optical Society of America.

Zhang W.L.,University of Electronic Science and Technology of China | Jiang Y.,University of Electronic Science and Technology of China | Zhu Y.Y.,University of Electronic Science and Technology of China | Wang F.,University of Electronic Science and Technology of China | Rao Y.J.,University of Electronic Science and Technology of China
Optics Letters | Year: 2013

A method for realizing low-threshold all-optical bistable logic control is proposed based on Tamm plasmons (TPs), which are formed in an asymmetric dielectric Bragg reflector (DBR)-metal-DBR (ADMD) structure with a layer of Kerr medium embedded. The ADMD structure supports two TPs due to coupling of trapped modes at each metal-DBR interface, generating two dips in the structure's reflection spectrum. Thus, control (i.e., pump) and controlled (i.e., probe) light with wavelengths close to the two dips, respectively, can be imported. It is verified theoretically that, thanks to the enhanced Kerr nonlinearity related to excitation of high-quality TP, bistable switching at very low injection intensity can be initiated by strength or direction variation of the pump. Meanwhile, the probe changes correspondingly with the pump. Thus, all-optical bistable logic operation of the probe can be controlled by the pump. © 2013 Optical Society of America.

Xu H.,University of Electronic Science and Technology of China | Yang L.,University of Electronic Science and Technology of China
Optics Letters | Year: 2013

We examine mode couplings in chiral fiber grating (CFG) with N-fold rotation symmetry in the cross section and show how the angular momentum matching condition in couplings determines the generation and conversion of orbital angular momentum (OAM) beams. Then we discuss interactions of OAM and spin angular momentum in single- and double-helix long-period CFGs excited by the fundamental core modes. Subsequently, taking righthanded elliptic-core long-period CFGs as example, we demonstrate a dual-OAM converter generating OAM beams with charge +2 and charge +4 at dual wavelengths, both with a conversion efficiency greater than 97%, as well as a broadband converter based on adiabatic coupling, with a bandwidth about 10 nm for a conversion efficiency greater than 95%. © 2013 Optical Society of America.

Xu X.,University of Electronic Science and Technology of China | Lou C.,University of Electronic Science and Technology of China
International Journal of Advancements in Computing Technology | Year: 2012

This paper introduces the application of decision tree algorithm in English vocabulary item selection, and explores the reliability of the item difficulty classifier, generated by the algorithm. The study results show that the classifiers generated by algorithm J48 and FT can effectively and efficiently predict the classification of the given items with an accuracy of over 85% and 91% respectively. This empirical study is the first time that decision tree algorithms are applied in English vocabulary test item selection.

Ping Z.,University of Electronic Science and Technology of China | Tian P.,University of Electronic Science and Technology of China
International Journal of Advancements in Computing Technology | Year: 2012

To reduce the computational complexity of motion estimation in H.264/AVC video coding, this paper proposes a global to local search algorithm based on particle swarm optimization and chaotic search. Firstly, global motion vector is obtained through particle swarm optimization applied to motion estimation. Then, chaotic search is used for local motion estimation to increase search accuracy. In addition, early and iterative termination strategies are adopted to further reduce computational complexity. Experimental results show that the proposed algorithm saves the average motion estimation times up 19-51% and 12-38% for UMHexagonS and EPZS algorithm, respectively, which are adopted in H.264/AVC video coding. Meanwhile, the proposed algorithm has insignificant degradation of rate distortion performance compared with UMHexagonS and EPZS algorithm.

Yang Y.,University of Electronic Science and Technology of China | Dong Y.,Soochow University of China | Zhao C.,Soochow University of China | Cai Y.,Soochow University of China
Optics Letters | Year: 2013

A theoretical model is proposed to describe a novel vortex beam named anomalous vortex (AV) beam. Analytical propagation formula for the proposed beam passing through a paraxial ABCD optical system is derived, and the propagation properties of such beam in free space are studied numerically. It is interesting to find that an AV beam will eventually become an elegant Laguerre-Gaussian beam in the far field (or in the focal plane) in free space. Furthermore, we report experimental generation of an AV beam and measure its propagation properties. Our experimental results are consistent with the theoretical predictions. © 2013 Optical Society of America.

Xia H.,University of Electronic Science and Technology of China | Li H.,University of Electronic Science and Technology of China | Lan C.,University of Electronic Science and Technology of China | Li C.,University of Electronic Science and Technology of China | And 3 more authors.
Optics Express | Year: 2014

We demonstrate an erbium-doped fiber laser passively modelocked by a multilayer molybdenum disulfide (MoS2) saturable absorber (SA). The multilayer MoS2 is prepared by the chemical vapor deposition (CVD) method and transferred onto the end-face of a fiber connector. Taking advantage of the excellent saturable absorption of the fabricated MoS2-based SA, stable mode locking is obtained at a pump threshold of 31 mW. Resultant output soliton pulses have central wavelength, spectral width, pulse duration, and repetition rate of 1568.9 nm, 2.6 nm, 1.28 ps, and 8.288 MHz, respectively. The experimental results show that multilayer MoS2 is a promising material for ultrafast laser systems. © 2014 Optical Society of America.

Yu M.X.,University of Electronic Science and Technology of China
International Journal of Antennas and Propagation | Year: 2016

This paper investigates a novel X-band microstrip-to-microstrip vertical via transition with matching pads loaded signal via. This design has been proposed for a multilayer substrate package. The matching pads, which are located in the center of the signal via on each ground layer, are adopted to further improve the impedance matching level and thus attain better signal transition performance. A physics-based equivalent circuit modeling approach has been employed for this research. The right angle MS-to-MS via transition was also designed using this technique. The simulated S-parameters indicate that the match-pad design made a breakthrough in achieving an approximate-15 dB wide-band return loss reduction. The measured S-parameter of MS-to-MS transition showed that return loss with the matching pads is better than that without the matching pads. © 2016 M. X. Yu.

Deng H.X.,University of Electronic Science and Technology of China | Deng H.X.,University of Michigan | Zu X.T.,University of Electronic Science and Technology of China | Xiang X.,University of Electronic Science and Technology of China | Sun K.,University of Michigan
Physical Review Letters | Year: 2010

A theory of photon-assisted impact ionization in solids is presented. Our theory makes a quantum description of the new impact ionization-cold avalanche ionization recently reported by P.P. Rajeev, M. Gertsvolf, P.B. Corkum, and D.M. Rayner. The present theory agrees with the experiments and can be reduced to the traditional impact ionization expression in the absence of a laser. © 2010 The American Physical Society.

Jia X.-H.,Sichuan Normal University | Ji X.-L.,Sichuan Normal University | Xu C.,Sichuan Normal University | Wang Z.-N.,University of Electronic Science and Technology of China | Zhang W.-L.,University of Electronic Science and Technology of China
Optics Express | Year: 2014

All-optical temporal integrator using phase-shifted distributedfeedback semiconductor optical amplifier (DFB-SOA) is investigated. The influences of system parameters on its energy transmittance and integration error are explored in detail. The numerical analysis shows that, enhanced energy transmittance and integration time window can be simultaneously achieved by increased injected current in the vicinity of lasing threshold. We find that the range of input pulse-width with lower integration error is highly sensitive to the injected optical power, due to gain saturation and induced detuning deviation mechanism. The initial frequency detuning should also be carefully chosen to suppress the integration deviation with ideal waveform output. ©2014 Optical Society of America

Peng F.,University of Electronic Science and Technology of China | Wu H.,University of Electronic Science and Technology of China | Jia X.-H.,University of Electronic Science and Technology of China | Rao Y.-J.,University of Electronic Science and Technology of China | And 2 more authors.
Optics Express | Year: 2014

An ultra-long phase-sensitive optical time domain reflectometry (φ-OTDR) that can achieve high-sensitivity intrusion detection over 131.5km fiber with high spatial resolution of 8m is presented, which is the longest φ-OTDR reported to date, to the best of our knowledge. It is found that the combination of distributed Raman amplification with heterodyne detection can extend the sensing distance and enhances the sensitivity substantially, leading to the realization of ultra-long φ-OTDR with high sensitivity and spatial resolution. Furthermore, the feasibility of applying such an ultra-long φ-OTDR to pipeline security monitoring is demonstrated and the features of intrusion signal can be extracted with improved SNR by using the wavelet detrending/denoising method proposed. © 2014 Optical Society of America.

Li X.D.,Nanyang Technological University | Chen T.P.,Nanyang Technological University | Liu Y.,University of Electronic Science and Technology of China | Leong K.C.,Globalfoundries
Optics Express | Year: 2014

Evolution of dielectric function of Al-doped ZnO (AZO) thin films with annealing temperature is observed. It is shown that the evolution is due to the changes in both the band gap and the free-electron absorption as a result of the change of free-electron concentration of the AZO thin films. The change of the electron concentration could be attributed to the activation of Al dopant and the creation/annihilation of the donor-like defects like oxygen vacancy in the thin films caused by annealing. © 2014 Optical Society of America.