Chengdu, China

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


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Patent
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.


Quan G.,University of Electronic Science and Technology of China | Li G.,University of Electronic Science and Technology of China
Proceedings of 2016 IEEE Advanced Information Management, Communicates, Electronic and Automation Control Conference, IMCEC 2016 | Year: 2016

The paper has proposed an adaptive beam forming method based on the secondary combination of the array elements. After the partition of the array, the adaptive beam is achieved by the sub-array for the desired signals and the jamming signals, and the jamming signals are restrained deeply by the pattern of the sub-array. The outputs of the sub-arrays are combined secondarily as the array elements. The pattern of the secondary combination array is synthesized to compensate the pattern of the sub-array oppositely. The simulation for the uniform linear array (ULA) proves the effectiveness of the method. © 2016 IEEE.


QIN X.,University of Electronic Science and Technology of China | CHO S.Y.,Gyeongsang National University
Acta Mathematica Scientia | Year: 2017

In this article, fixed points of generalized asymptotically quasi-ϕ-nonexpansive mappings and equilibrium problems are investigated based on a monotone projection algorithm. Strong convergence theorems are established without the aid of compactness in the framework of reflexive Banach spaces. © 2017 Wuhan Institute of Physics and Mathematics


Yi B.,University of Electronic Science and Technology of China | Chen X.,University of Electronic Science and Technology of China
IEEE Transactions on Power Electronics | Year: 2017

In this paper, a high-side p-channel LDMOS (p-LDMOS) with an auto-biased n-channel LDMOS (n-LDMOS) based on Triple-RESURF technology is proposed. The p-LDMOS utilizes both carriers to conduct the on-state current; therefore, the specific on-resistance (Ron,sp ) can be much reduced because of much higher electron mobility. The simulation result shows that the proposed 300-V p-LDMOS obtains a Ron,sp of 16.97 mω/cm2, which is about 65% reduced compared with the Triple-RESURF silicon limit and is comparable to an optimized n-LDMOS (BV = 340 V, Ron,sp = 18 mω/cm2). In addition, due to larger current capability, the active area of the proposed p-LDMOS is only about one third of an optimized Triple-RESURF p-LDMOS. The turn-on (tr ) and turn-off time (tf ) are reduced by 51.2% and 40.0%, compared to the optimized Triple-RESURF p-LDMOS, respectively. © 2016 IEEE.


Xiao M.,University of Electronic Science and Technology of China | Nagamochi H.,Kyoto University
Leibniz International Proceedings in Informatics, LIPIcs | Year: 2016

In this paper, we study the problem of finding an integral multiflow which maximizes the sum of flow values between every two terminals in an undirected tree with a nonnegative integer edge capacity and a set of terminals. In general, it is known that the flow value of an integral multiflow is bounded by the cut value of a cut-system which consists of disjoint subsets each of which contains exactly one terminal or has an odd cut value, and there exists a pair of an integral multiflow and a cut-system whose flow value and cut value are equal; i.e., a pair of a maximum integral multiflow and a minimum cut. In this paper, we propose an O(n)-time algorithm that finds such a pair of an integral multiflow and a cut-system in a given tree instance with n vertices. This improves the best previous results by a factor of Ω(n). Regarding a given tree in an instance as a rooted tree, we define O(n) rooted tree instances taking each vertex as a root, and establish a recursive formula on maximum integral multiflow values of these instances to design a dynamic programming that computes the maximum integral multiflow values of all O(n) rooted instances in linear time. We can prove that the algorithm implicitly maintains a cut-system so that not only a maximum integral multiflow but also a minimum cut-system can be constructed in linear time for any rooted instance whenever it is necessary. The resulting algorithm is rather compact and succinct. © Mingyu Xiao and Hiroshi Nagamochi.


Huang W.-H.,TU Dortmund | Yang M.,University of Electronic Science and Technology of China | Chen J.-J.,TU Dortmund
Proceedings - Real-Time Systems Symposium | Year: 2017

When concurrent real-time tasks have to access shared resources, to prevent race conditions, the synchronization and resource access must ensure mutual exclusion, e.g., by using semaphores. That is, no two concurrent accesses to one shared resource are in their critical sections at the same time. For uniprocessor systems, the priority ceiling protocol (PCP) has been widely accepted and supported in real-time operating systems. However, it is still arguable whether there exists a preferable approach for resource sharing in multiprocessor systems. In this paper, we show that the proposed resource-oriented partitioned scheduling using PCP combined with a reasonable allocation algorithm can achieve a non-trivial speedup factor guarantee. Specifically, we prove that our task mapping and resource allocation algorithm has a speedup factor 11-6/(m+1) on a platform comprising m processors, where a task may request at most one shared resource and the number of requests on any resource by any single job is at most one. Our empirical investigations show that the proposed algorithm is highly effective in terms of task sets deemed schedulable. © 2016 IEEE.


Sun X.,University of Electronic Science and Technology of China | Wang Z.,University of Electronic Science and Technology of China | Fu Y.Q.,Northumbria University
Carbon | Year: 2017

Effects of grain boundaries (GBs) in graphene on adsorption and diffusion of sodium were investigated using first principle calculations. Results showed that the presence of GBs in graphene enhanced the adsorption of sodium, with their adsorption energies in the range of −1.32∼-0.79 eV, which were lower than the value of −0.67 eV for sodium adsorbed on pristine graphene. The diffusion energy barriers were in the range of 0.09–0.35 eV when sodium was diffused along GBs of graphene, whereas they were decreased when sodium was gradually diffused into the GBs. Results showed that graphene with GBs had a larger energy storage capacity for sodium than the pristine one, indicating that it can be used as a good anode material for sodium ion batteries. © 2017 Elsevier Ltd


Xia Y.,University of Electronic Science and Technology of China | Tang Z.-C.,University of Electronic Science and Technology of China
RSC Advances | Year: 2017

Various parameters, such as biodiesel price, capital cost, interest rate, operating cost, feedstock price, maintenance rate, biodiesel conversion efficiency and glycerol price, may exhibit variation in the techno-economic assessments of biodiesel production within the project's lifetime due to economic and technical uncertainties. This paper first defines a new indicator for techno-economic assessments of biodiesel production when all uncertain parameters are regarded as being uniformly distributed within their variation ranges. This new indicator is named economical infeasibility probability (EIP), which defines the probability that total profit, payback period and net present value (NPV) of biodiesel production or one of them or two of them do not satisfy the prescribed requirements, and the Monte Carlo Simulation (MCS) method is employed to evaluate EIP. Based on economical infeasibility analysis, the sensitivity analysis of EIP with respect to an individual uncertain parameter is defined, and MCS is utilized to evaluate the effect. It is found that EIP for the studied biodiesel production is 0.3676 under the selected distributions of uncertain parameters, and biodiesel price, feedstock price, biodiesel conversion efficiency and operating cost have significant effects on EIP, while capital cost, maintenance rate, interest rate and glycerol price have negligible effects. © The Royal Society of Chemistry.


Wang Z.,University of Electronic Science and Technology of China | Liu Q.,University of Electronic Science and Technology of China
IOP Conference Series: Earth and Environmental Science | Year: 2017

The clustering of buildings on the city map is an important field of cartographic and the main step to resolve issues related to the scale of the city map transformation process. The development of computer technology promotes the studies of cartographic and modelling algorithms. In order to achieve automatic clustering of map elements, the domestic and foreign scholars have proposed numerous automatic clustering algorithms. Although each algorithm works for specific problems, all algorithms are based on the graphical analysis transformation of building polygons on the map. By reading and analyzing current development of domestic and foreign researches, we find out that map building clustering needs more inspiring interactive features and automatic integrated decision-making simulation functions. It needs to improve the visualization software and integrated automatic intelligence, increase the proportion of the batch to support implementation of automated cartographic generalization to a higher level. © Published under licence by IOP Publishing Ltd.


Wang P.-P.,University of Maryland University College | Yu S.-J.,University of Maryland University College | Govorov A.O.,Ohio University | Govorov A.O.,University of Electronic Science and Technology of China | Ouyang M.,University of Maryland University College
Nature Communications | Year: 2017

Cooperative chirality phenomena extensively exist in biomolecular and organic systems via intra-and inter-molecular interactions, but study of inorganic materials has been lacking. Here we report, experimentally and theoretically, cooperative chirality in colloidal cinnabar mercury sulfide nanocrystals that originates from chirality interplay between the crystallographic lattice and geometric morphology at different length scales. A two-step synthetic scheme is developed to allow control of critical parameters of these two types of handedness, resulting in different chiral interplays expressed as observables through materials engineering. Furthermore, we adopt an electromagnetic model with the finite element method to elucidate cooperative chirality in inorganic systems, showing excellent agreement with experimental results. Our study enables an emerging class of nanostructures with tailored cooperative chirality that is vital for fundamental understanding of nanoscale chirality as well as technology applications based on new chiroptical building blocks. © 2017 The Author(s).


Liu G.,University of Electronic Science and Technology of China | Li L.,University of Electronic Science and Technology of China
International Conference on Signal Processing Proceedings, ICSP | Year: 2017

Parallel processing technology has become great of importance in a communication channel and error correction techniques are used to accomplish reliable data transmission, especially in redundant residue number system(RRNS). This paper presented a modified algorithm for double error correction in RRNS. We can correct double errors in RRNS more efficiently compared to other algorithms for double errors correction. The modified algorithm reduces the complexity of the hardware and the latency obviously. © 2016 IEEE.


Cheng X.,University of Electronic Science and Technology of China | Lou N.,University of Electronic Science and Technology of China
2016 IEEE International Conference on Communication Systems, ICCS 2016 | Year: 2016

Due to the potential of supporting multi-gigabit data rate, millimeter-wave (MMW) communication is deemed as a key technology for next-generation WLAN and 5G cellular systems. To fully realize the potential of MMW communication, we have to overcome some difficulties, such as phase noise (PHN). The immature CMOS fabrication incurs a relatively large PHN to MMW systems. Without suppression, the PHN can severely degrade the system performance. In this paper, we present a novel PHN suppression scheme for MMW single carrier frequency domain equalization (SC-FDE) systems. The key to suppress PHN is to estimate it as accurately as possible. Capitalizing on the statistical sparsity of MMW PHN in the basis formed by the eigenvectors of PHN autocorrelation matrix, we formulate the PHN estimation into the framework of compressive sensing (CS). In particular, we modify the sparse Bayesian leaning (SBL) strategy to estimate the involved PHN using the data decision available. The obtained PHN estimate is used to compensate for the PHN effect, followed by FDE operation and a re-demodulation of data symbols. This process iterates several times such that we can significantly improve the BER performance. Thanks to the modified SBL adopted, the proposed scheme can not only effectively mitigate the adverse effect of PHN, thereby leading to better performance, but also bear a low computation complexity. © 2016 IEEE.


Dong F.,University of Electronic Science and Technology of China | Pan Y.,University of Electronic Science and Technology of China
ACM International Conference Proceeding Series | Year: 2016

Haze has a great impact on the picture clarity, which cannot meetthe needs of high definition image areas. In this paper, image haze removal algorithms are studied, where the haze image are treated and restored using dark channel prior theory. Dark channel prior is an image Statistics Law - within the vast majority of outdoor haze free image, there are always some points of a color channel whose value is close to zero; Using the law to establish a model, you can well recover haze free image. © 2016 ACM.


Zou Y.,University of Electronic Science and Technology of China | Wan Q.,University of Electronic Science and Technology of China
2016 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference, APSIPA 2016 | Year: 2016

This paper considers the problem of moving target localization in noncoherent distributed multiple-input multiple-output (MIMO) radar systems by using the bistatic range and range rate measurements. We propose a weighted least squares (WLS) method to estimate the target position and velocity, and then use the semidefinite programming (SDP) method to improve the accuracy of the WLS estimation by relaxing the constraints that exist in the WLS solution. Simulation results are included to show the performance of the proposed algorithm. It is shown that the proposed method can reach the Cramer-Rao lower bound (CRLB) in a range of moderate measurements noise, and the proposed algorithm is robust to some special geometries, in which the two-step weighted least squares-based (2SWLS-based) methods will be failed. © 2016 Asia Pacific Signal and Information Processing Association.


Zheng Q.,University of Electronic Science and Technology of China | Zhang H.,University of Electronic Science and Technology of China
Circuits, Systems, and Signal Processing | Year: 2017

This paper investigates the robust stabilization problem for a class of polytopic uncertain continuous-time nonlinear switched systems without stable subsystems. In order to analyze the stability of switched systems without stable subsystems, we propose a novel switching Lyapunov function. This new switching Lyapunov function has the “switching-decreasing” property at switching instant. To obtain less conservative results, we propose the switching-decreasing parameter-dependent Lyapunov function (SDPDLF) to investigate the studied switched systems. By using the SDPDLF approach and maximum average dwell time technique, a sufficient condition is obtained to guarantee the studied switched systems to be asymptotically stable. It is shown that the average dwell time should be less than a upper bound. This is different from some previous work, where the average dwell time is larger than a lower bound. Finally, a numerical example and a practical example are provided to illustrate the effectiveness of our results. © 2016, Springer Science+Business Media New York.


Yang S.,Science and Technology on Electronic Information Control Laboratory | Tang W.,University of Electronic Science and Technology of China
Proceedings - 2016 UKSim-AMSS 18th International Conference on Computer Modelling and Simulation, UKSim 2016 | Year: 2016

To reduce the cost of network-wide broadcast in wireless sensor networks (WSNs), it's a common practice to establish a connected dominating set (CDS). A lot of algorithms have been proposed to construct CDS, and most of them aim at reducing the size of the created CDS. Existing distributed algorithms require that all nodes exchange announcement messages to acquire local topology in order to construct CDS. However, the process of construction and maintenance of CDS can cause huge overhead, especially in the context of WSNs, where the node density is high and the quantity of nodes is large. In this paper, we focus upon reducing the overhead of the CDS construction process, and propose a highly efficient distributed algorithm based on our previous work. We show that, to construct a CDS, a portion of nodes in the network don't have to generate announcement messages. An opportunistic announcement scheme is presented to determine such nodes. Simulation results show that the proposed algorithm greatly reduces the overhead compared to existing algorithms, while the size of the established CDS remains the same. An interesting fact is shown that certain nodes can just keep silent during the whole process of construction and maintenance of CDS. © 2016 IEEE.


Zhou Y.,University of Electronic Science and Technology of China | Zu X.,University of Electronic Science and Technology of China
Electrochimica Acta | Year: 2017

A search for high-efficiency electrode materials is crucial for the application of Li-ion batteries (LIBs). Using density functional theory (DFT), we assess the Mn2C sheet, a new MXene, as a suitable electrode material. Our studies show that Li atoms can bind strongly to the Mn2C sheet, with low adsorption energy of −1.93 eV. A pristine Mn2C sheet exhibits metallic characteristic, offering an intrinsic advantage for the transportation of electrons in material. A very low energy barrier of 0.05 eV is predicted, showing that Li ion can easily and freely migrate on the Mn2C sheet. In addition, with the increase of Li content, adsorption energy varies minimally within a range of energy that spans only 0.27 eV, showing that lithiation to a high content is feasible. Furthermore, we found that, because of the bilayer adsorptions on both sides of the Mn2C sheet, the theoretical capacity of the Mn2C sheet is 879 mAhg−1, which is greater than that of most two-dimentional (2D) electrode materials. All these results reveal a new promising MXene material for LIBs. We also studied the effects of oxidation and fluorination on the electrochemical properties of the Mn2C sheet and found that oxidation and fluorination will fade the electrochemical properties of the Mn2C sheet in general. © 2017


Yin L.,University of Electronic Science and Technology of China | Liu Y.,University of Electronic Science and Technology of China
Proceedings of 2016 IEEE 15th International Conference on Cognitive Informatics and Cognitive Computing, ICCI*CC 2016 | Year: 2016

Many biclustering algorithms have been proposed in analyzing the gene expression data and ensemble biclustering methods can improve performance of the biclustering algorithm. We propose a new method of obtaining a variety of constituent biclusters which use different quality measures of bicluster. To demonstrate the efficiency of our methods, experiment on six real gene expression data shows the diversity and biological significance of the biclusters obtained by our methods are higher than that of the compared methods. © 2016 IEEE.


Cai X.,University of Electronic Science and Technology of China | Long J.,University of Electronic Science and Technology of China
International Conference on Signal Processing Proceedings, ICSP | Year: 2017

A very compact polarization diversity quadruple-band-notched ultrawideband (UWB) two-element MIMO antenna and a small size MIMO antenna with four elements are presented in this paper. Firstly, the multi-input multi-output (MIMO) antenna has two identical monopoles. Its high isolation which is less than -20 dB is achieved without using any complex decoupling methods. Secondly, to obtain a band-notched function and improve the area utilization of the antenna, the symmetric split ring resonators (SRRs) are etched next to the feedline and the co-directional complementary split-ring resonator (CSRR) is embedded inside the radiating patch. Thirdly, curve ground plane and arc radiating patch can improve impedance matching performance of the antenna. The two proposed antennas exhibit the suitability for wireless diversity communications. © 2016 IEEE.


Yang F.,University of Electronic Science and Technology of China | Zhang X.,Texas A&M University
2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings | Year: 2016

The impulsive noise effect is one of the most dominant factors to cause performance degradation for power-line communication (PLC) links. Most reported literatures characterize such an impulsive noise based on the Bernoulli-Gaussian or Middleton's approach. However those models may not truly depict the noise characteristics of the impulses with stable property. The symmetric alpha-stable (SαS) noise model stems from the generalized central limit theorem (GCLT), which describes practical PLC impulsive noise well. By modeling the bandpass asynchronous impulsive noise as additive white symmetric alpha- stable noise (AWSαSN), we investigate the analytical symbol error rate (SER) performance of a PLC narrowband system link in smart grid networks. Based on the zero-order statistics, we evaluate the strength of the SαS noise using geometric signal-to-noise ratio (GSNR), and explore the uncoded error performance for the conventional linear receiver. Through extensive experiments and numerical analyses, we show that the analytical SER performance of a PLC link matches the simulation results well, which provides suitable benchmarks and guidance for designation of coded systems. © 2016 IEEE.


Long R.,University of Electronic Science and Technology of China | Ouyang J.,University of Electronic Science and Technology of China
Progress In Electromagnetics Research C | Year: 2017

Matrix method for phased array calibration is an excitation reconstruction method by solving the linear equations based on the linear relationship between the measured near-field data and element excitations. In this paper, we propose a modified matrix method, in which the phased array model is simplified, to measure the element excitations of planar phased array. Our method reduces measurement time greatly at the cost of introducing some calibration errors. The introduced calibration errors can be minimized with the array excitation strategy proposed in this paper. Experimental results validate the effectiveness of our methods in calibrating planar phased arrays. © 2017, Electromagnetics Academy. All Rights Reserved.


Chen B.,Southern Methodist University | Chen B.,Zhejiang University | Ni D.,University of Electronic Science and Technology of China
International Journal of Industrial Organization | Year: 2017

We study optimal pricing issues for a monopolist selling two indivisible goods to a continuum of consumers with correlated private valuations over the goods, where the (positive or negative) correlation is modeled using copulas in the Fréchet family. We derive explicit optimal pricing schemes and comparative statics results for various environments in our setting. The optimal pricing schemes can take several forms, including pure bundling, partial mixed bundling, and mixed bundling, depending jointly on the degrees of asymmetry and correlation of the consumers’ valuations. The explicit optimal pricing schemes also enable us to investigate whether and how the monopolist's profit can be further improved via random assignments. © 2017 Elsevier B.V.


Peng C.,University of Electronic Science and Technology of China | Zou J.,University of Electronic Science and Technology of China | Lian L.,University of Electronic Science and Technology of China
Renewable and Sustainable Energy Reviews | Year: 2017

Recently, with the rapid growth of electric vehicle (EV) and development of Vehicle-to-Grid (V2G) technology, EVs participating in frequency regulation service to support power grid operation has been seen as one of the most promising power grid ancillary services provided by EVs integrated in grid. The dispatching strategy of EVs determines the feasibility and efficiency of EVs participating in frequency regulation, which have been received extensive researches. This paper will review the current dispatching strategies of EVs participating in frequency regulation. At first, the system structure of EVs participating frequency regulation is introduced. The stability and economy of EVs participating frequency in grid are analyzed. Secondly, the existing dispatching strategies are categorized into strategies for stability problem and strategies for economy problem, which are discussed in detailed. Finally, the existing problems and the future researches in EVs participating in frequency regulation on power grid are summarized. © 2016 Elsevier Ltd


Cheng H.,University of Electronic Science and Technology of China | Deng H.,University of Electronic Science and Technology of China | Wang Y.,University of Electronic Science and Technology of China | Wei M.,University of Electronic Science and Technology of China
Journal of Alloys and Compounds | Year: 2017

The influence of the ZnO buffer layer thickness on the structural, electrical, optical and surface properties of Ga-doped ZnO (GZO) films deposited on glass substrates by RF magnetron sputtering were investigated. X-ray diffraction results showed the obtained films had highly c-axis oriented with hexagonal (002) structures and GZO film with 20 nm buffer layer had the best crystalline quality. The resistivity in GZO/ZnO bi-layer films decreased significantly than that in GZO film without a ZnO buffer layer, and GZO film with 20 nm buffer layer showed the lowest resistivity of 4.09 × 10−4 Ω cm. The bi-layer films exhibited the highest transmittance of over 80% in the visible light range and displayed a low near infrared transmittance. The correlation between surface morphology and wettability was studied and GZO/ZnO bi-layer films exhibited hydrophobic property with contact angle of θ from 104° to 108.5°, indicating acceptable property of environmental durability. © 2017 Elsevier B.V.


Guo L.,University of Electronic Science and Technology of China | Chen Y.,University of Electronic Science and Technology of China | Yang S.,University of Electronic Science and Technology of China
IEEE Transactions on Antennas and Propagation | Year: 2017

In this paper, characteristic mode (CM) formulations are developed from surface integral equation (SIE) for the modal analysis of dielectric coated conducting bodies. The electric field integral equation-Poggio, Miller, Chang, Harrington, Wu, and Tsai SIE is used for modeling the dielectric coated conducting bodies. By ensuring the field continuity on the interface boundary, two types of generalized eigenvalues equations are formulated to determine the resonant behavior of the dielectric coated conducting bodies. Following Poynting's theorem, the resultant eigenvalues indicate the ratio of the imaginary and real part of the complex power for each CM. Zero eigenvalues indicate the resonance in dielectric coated conducting bodies. The corresponding modal fields provide with clear physical insights into the radiation/scattering mechanisms. Numerical results are presented to demonstrate the accuracy of the proposed CM formulations. © 1963-2012 IEEE.


Wang J.,University of Electronic Science and Technology of China | Cheng Y.J.,University of Electronic Science and Technology of China
International Journal of Antennas and Propagation | Year: 2017

A W-band hybrid unequal feeding network of waveguide and substrate integrated waveguide (SIW) is presented in this paper. It comprises a two-way hybrid waveguide-SIW E-plane divider and an unequal SIW dividing network. Firstly, the two-way hybrid divider is developed to realize the waveguide-to-SIW vertical transition and power division at the same time. Besides, it has a wider bandwidth and more compact configuration compared with those of conventional structures including a transition and a cascading divider. Secondly, an SIW 1-to-16-way unequal dividing network is developed with the phase self-compensation ability. This W-band dividing network is able to generate the desired amplitude and phase distribution. Finally, two back-to-back SIW 16 × 16 antenna arrays are grouped and fed by the proposed feeding network. The low sidelobe levels (SLLs) can be achieved at E- and H-plane of the antenna. The total aperture size of the antenna is 15% less than that of a conventional antenna with a separated divider and a transition. With such a multifunctional feeding network, the antenna is able to achieve low loss and high efficiency as well. © 2017 Jun Wang and Yu Jian Cheng.


Yu S.,University of Electronic Science and Technology of China | Xiang Y.,University of Electronic Science and Technology of China
Journal of Computational and Theoretical Nanoscience | Year: 2017

The challenge of multi-dimensional performance optimization has been extensively addressed in the literature based on deterministic parameters. Since resources in Cloud Computing platforms are geographically separated and heterogeneous, it is rather difficult to apply a uniform distribution algorithm for achieving various optimization goals. Based on the analysis of cloud service performance measures, this paper proposes an approach for optimal network resource distribution managed by the multi-agent system (MAS), which is aimed to satisfy both the users' and the service providers' requirements. Moreover, a communication algorithm that uses the universal generating function technique is proposed to obtain the service time distribution efficiently. Copyright © 2017 American Scientific Publishers.


Zhang L.,No. 2006 | Zhang H.,University of Electronic Science and Technology of China | Ding X.,Davis
IET Generation, Transmission and Distribution | Year: 2017

In this study, the authors investigate the non-fragile H∞ filtering for large-scale power systems with sensor networks to estimate the state of each subsystem and send the states to different sites. First, for the purpose of enhancing monitoring efficiency, each sensor measures the corresponding subsystem, which can avoid the paralysis of the entire monitoring system caused by the damage of a sensor. Second, they construct the non-fragile filter to adapt the uncertain environment. Sufficient conditions are obtained to ensure that the filtering error system is asymptotically stable with a prescribed H∞ performance level based on the robust control approach. The filter parameters are determined by solving a set of linear matrix inequalities. A simulation example, which shows the efficiency of the proposed methods is included in this study. © The Institution of Engineering and Technology 2016.


Rao Y.,University of Electronic Science and Technology of China
Journal of Internet Technology | Year: 2016

Since many activities of interest often occur in the dark environment, nighttime video enhancement is important for video surveillance. In this paper, we propose a novel and effective nighttime video enhancement algorithm for video surveillance applications by using illumination compensation, which fuses video frames from high quality daytime background and low quality nighttime video. For further improving the perceptual quality of the moving objects, an algorithm based on object region ratio average is also proposed. Experimental results show that the proposed algorithm can obviously improve the visual quality from the conventional methods.


Zheng X.-Y.,Chengdu Engineering Corporation Ltd | Shen J.,University of Electronic Science and Technology of China
Civil Engineering and Urban Planning IV - Proceedings of the 4th International Conference on Civil Engineering and Urban Planning, CEUP 2015 | Year: 2016

Diversion tunnel is often characterized by long tunnel line, extremely complicated geologic conditions and construction techniques, great embedded depth, inspection and maintenance difficulties. Consequently, the problems of construction management and engineering construction schedule control could occur, especially diversion tunnel groups. In this paper, a new ontology-based model for diversion tunnel is proposed, and design and development of the context management system for mobile computing, which is an intelligent context-aware system, is described. Moreover, knowledge sharing and knowledge reuse are also provided by using the ontology model. The context management system makes use of rulebased reasoning that provides derivation of a high-level context from a low-level context. The test results validate the feasibility of the context management system. The achievements of this paper could provide references for the management of diversion tunnel or similar rock engineering. Technical support and scientific basis are also provided for its process control, safety warning, later inspection and maintenance. © 2016 Taylor & Francis Group, London.


Yuan X.,University of Electronic Science and Technology of China | Gan L.,University of Electronic Science and Technology of China
Signal Processing | Year: 2017

In this paper, a novel subspace method is proposed to reconstruct the interference-plus-noise covariance matrix (IPNCM) according to its definition, which can fundamentally eliminate the signal of interest (SOI) component from the sample covariance matrix (SCM). The central ideal is that each interference steering vector (SV) is estimated by the vector lying within the intersection of two subspaces while its power obtained by using the Capon spectral estimator. The first subspace is the interference subspace and it is obtained from each interference covariance matrix term calculated by integrating over each interference angular sector. The second one is the signal-interference subspace got from the SCM. Then a more precise IPNCM is reconstructed based on these accurate estimations. Meanwhile the signal covariance matrix is calculated by integrating over the SOI angular sector so that a new SV estimation of SOI can be obtained from its prime eigenvector. Finally, based on the new IPNCM and the SV of SOI, a novel robust beamformer is formulated to improve the robustness against array model mismatches. Simulation results demonstrate that the proposed beamformer outperforms other existing reconstruction-based beamformers and almost attains the optimal performance in both low and high input signal-to-noise ratio (SNR) cases. © 2016 Elsevier B.V.


Benlic U.,Queen Mary, University of London | Benlic U.,University of Electronic Science and Technology of China | Burke E.K.,Queen Mary, University of London | Woodward J.R.,University of Stirling
Computers and Operations Research | Year: 2017

The problem of assigning gates to arriving and departing flights is one of the most important problems in airport operations. We take into account the real multi-criteria nature of the problem by optimizing a total of nine gate allocation objectives that are oriented both on convenience for airport/airline services and passenger comfort. As far as we are aware, this is the largest number of objectives jointly optimized in the GAP literature. Given the complexity of the considered problem, we propose a heuristic approach based on the Breakout Local Search (BLS) framework. BLS is a recent variant of the Iterated Local Search (ILS) with a particular focus on the perturbation strategy. Based on some relevant information on search history, it tries to introduce an appropriate degree of diversification by determining adaptively the number and type of moves for the next perturbation phase. Moreover, we use a new memory-based greedy constructive heuristic to generate a starting point for BLS. Benchmark instances used for our experiments and comparisons are based on information provided by Manchester Airport. © 2016 Elsevier Ltd


Zhao G.,University of Electronic Science and Technology of China | Fu J.,University of Michigan
Biotechnology Advances | Year: 2017

Cryopreservation has utility in clinical and scientific research but implementation is highly complex and includes labor-intensive cell-specific protocols for the addition/removal of cryoprotective agents and freeze-thaw cycles. Microfluidic platforms can revolutionize cryopreservation by providing new tools to manipulate and screen cells at micro/nano scales, which are presently difficult or impossible with conventional bulk approaches. This review describes applications of microfluidic tools in cell manipulation, cryoprotective agent exposure, programmed freezing/thawing, vitrification, and in situ assessment in cryopreservation, and discusses achievements and challenges, providing perspectives for future development. © 2017 Elsevier Inc.


Long S.,Chongqing University of Technology | Zhong S.,University of Electronic Science and Technology of China
Nonlinear Analysis: Hybrid Systems | Year: 2017

In this paper, the problem of stochastic stabilization for a class of discrete-time singular Markovian jump systems with time-varying delay is investigated. By using the Lyapunov functional method and delay decomposition approach, improved delay-dependent sufficient conditions are presented, which guarantee the considered systems to be regular, causal and stochastically stabilizable. Finally, some numerical examples are provided to illustrate the effectiveness of the obtained methods. © 2016 Elsevier Ltd.


Mao Y.,Binghamton University State University of New York | Zhang H.,University of Electronic Science and Technology of China | Zhang Z.,Binghamton University State University of New York
IEEE Transactions on Fuzzy Systems | Year: 2017

This paper investigates the finite-time exponential stability analysis and stabilization problem of discrete-time switched nonlinear systems without stable subsystems. In the stability analysis, the Takagi-Sugeno (T-S) fuzzy model is employed to approximate nonlinear subsystems. With two level functions, namely, crisp switching functions and local fuzzy weighting functions, we introduce switched fuzzy systems with approximation errors, which inherently contain both the features of the switched systems and T-S fuzzy systems. By constructing the 'decreasing-jump' piecewise Lyapunov-like functions and minimum dwell time technique, a finite-time exponential stability of switched fuzzy systems with bounded approximation errors is obtained. Then, based on the finite-time exponential stability, a multiobjective evolution algorithm (nondominated sorting genetic algorithm, NSGA-II), which considers two conflicting objectives, such as the average convergence error and the average switching cost, is proposed to generate tradeoff switching sequences to stabilize the discrete-time switched nonlinear systems over a finite-time interval. A numerical example and a practical example are provided to illustrate the effectiveness of the stability and the algorithm, respectively. © 2016 IEEE.


Wang J.,City University of Hong Kong | Wang L.,City University of Hong Kong | Ren J.,University of Electronic Science and Technology of China | Hovhannisyan H.,City University of Hong Kong
IEEE Wireless Communications | Year: 2017

As one of the cornerstones of networked systems, the design of resolution between names and resources, that is, name resolution, is crucial. In recent years, with the emerging research on future Internet architectures, many namespaces and resolution systems have been proposed. However, these namespaces and resolution systems are closed systems, where a system can only support one or more predefined namespaces and the policies for resolution among them. Such closed design lacks the flexibility of defining new resolution policy and interoperability among different networked systems. In this article, we analyze the existing namespaces and resolution systems in various network architectures and propose a generic name resolution framework, which can allow flexible namespace and resolution policy definition and enable interoperation among different network architectures. A prototype of such a name resolution system supporting the interoperability among WiFi, Zigbee, and Bluetooth, and the interoperability between NDN and HTTP is demonstrated. © 2002-2012 IEEE.


Zhang W.,University of Electronic Science and Technology of China | Hou X.,University of Electronic Science and Technology of China
Multimedia Tools and Applications | Year: 2017

The atmospheric light value is a critical parameter in defogging algorithms that are based on atmospheric scattering models. Any error in the atmospheric light value will impact directly on the accuracy of scattering computation and thus cause chromatic distortions in the restored images. To address this problem, this paper proposes a method that relies on clustering statistics to estimate the atmospheric light value. It starts by selecting in the original image some potential atmospheric light source points, which are grouped into point clusters using a clustering technique. From these clusters, several clusters containing candidate atmospheric light source points are selected; the points are then analyzed statistically, and the cluster containing the most candidate points is used for estimating the atmospheric light value. The mean brightness vector of the candidate atmospheric light points in the chosen point cluster is used as the estimate of the atmospheric light value, and their geometric center in the image is accepted as the location of atmospheric light. The experimental results suggest that this statistical clustering method produces more accurate atmosphere brightness vectors and light source locations. This accuracy translates to, from a subjective perspective, both a more natural defogging effect and improvements in various objective image quality indicators. © 2017 Springer Science+Business Media New York


Tang C.-J.,University of Electronic Science and Technology of China
Journal of Electronic Science and Technology | Year: 2017

This literature review on the research of embodied emotion addresses the aspects of the concepts of embodied emotion, the various theories or theses on the embodied emotion abroad and at home, some comments based on the literature are elicited and the discussions about the future research topics on embodied emotion are proposed.


Wang W.-Q.,University of Electronic Science and Technology of China | So H.C.,City University of Hong Kong | Farina A.,IEEE Aerospace and Electronic Systems Society BoG
IEEE Journal on Selected Topics in Signal Processing | Year: 2017

Time and frequency modulated arrays have numerous application areas including radar, navigation, and communications. Specifically, a time modulated array can create a beampattern with low sidelobes via connecting and disconnecting the antenna elements from the feed network, while the frequency modulated frequency diverse array produces a range-dependent pattern. In this paper, we aim to introduce these advanced arrays to the signal processing community so that more investigations in terms of theory, methods, and applications, can be facilitated. The research progress of time/frequency modulated array studies is reviewed and the most recent advances are discussed. Moreover, potential applications in radar and communications are presented, along with their technical challenges, especially in signal processing aspects. © 2016 IEEE.


Liang D.,University of Electronic Science and Technology of China | Xu Z.,University of Sichuan | Liu D.,Southwest Jiaotong University
Information Sciences | Year: 2017

Decision-theoretic rough sets (DTRSs) as a classic model of three-way decisions have been widely applied in the area of risk decision-making. When we confront the complicated and uncertain environment, one of challenges is to estimate the loss function of DTRSs. As a new generalization of fuzzy sets, dual hesitant fuzzy sets (DHFSs) can handle uncertain information more flexibly in the process of decision making and give a new measure for the determination of loss functions of DTRSs. To have more interesting results in the context of three-way decisions, we introduce the new hesitant format of DHFSs into DTRSs and explore a new three-way decision model. Firstly, we take into account the loss functions of DTRSs with dual hesitant fuzzy elements (DHFEs) and propose a dual hesitant fuzzy DTRS model. In order to satisfy the preconditions of three-way decisions, we analyze the normalized principle of loss functions under the dual hesitant fuzzy environment. Meanwhile, some properties of the expected losses are carefully investigated. Then, we further design two approaches for deriving three-way decisions with the new DTRS model, i.e., Method 1 and Method 2, which mainly relies on the comparisons among the expected losses. Method 1 is a general method based on the scores and the accuracies of DHFEs. Method 2 is a ranking method of possibility degrees with a stochastic strategy and enriches the comparisons among the expected losses. Finally, the assessment of emergency blood transshipment is used to illustrate and compare these proposed methods. © 2017 Elsevier Inc.


Wang Z.,University of Electronic Science and Technology of China | Wang Z.,University of California at Irvine | Heydari P.,University of California at Irvine
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2017

A study of operating condition and design methods is presented that enables the amplifiers to achieve the upper limit of their power gain at frequencies close to the device fmax. Using the gain-plane approach, the necessary and sufficient conditions to achieve this theoretical upper limit are obtained and the results are analytically verified. As will be demonstrated, the maximum power gain is achieved if and only if the imaginary part of Y12/Y21 becomes zero and the device operates at the edge of the unconditional stability region. In addition, a generic circuit solution comprising both a Y- and a Z-embedding network is proposed to achieve this upper limit. Simulations of a CMOS amplifier surrounded by an exemplary YZ-embedding network verify this study. © 2017 IEEE.


Xue M.,University of Electronic Science and Technology of China | Du Y.,University of Electronic Science and Technology of China
Mathematical Problems in Engineering | Year: 2017

In recent years, the decision-making models with hesitant fuzzy preference relations (HFPRs) have received a lot of attention by some researchers. Meanwhile, the previous studies normally adopt normalization technical means to ensure the same number for all elements, which biases original information of decision-makers. In order to overcome this problem, in this paper, the multiplicative consistency of HFPRs is defined and the highest consistent reduced HFPRs are obtained by means of fuzzy linear programming method from given HFPRs. The proposed regression method eliminates the unreasonable information and retains the reasonable information from a given HFPR. In addition, the proposed method overcomes drawbacks of Zhu and Xu's regression method and is more simple and effective. On account of the obtained reduced HFPRs by the proposed regression method, a GDM model is established. Finally, a supplier selection problem was researched to present the effectiveness and pragmatism of the proposed approach, which proved that the method could offer beneficial insights into the GDM procedure. © 2017 Min Xue and Yifei Du.


Zhong Y.,University of Electronic Science and Technology of China | Liu D.,University of Electronic Science and Technology of China
Proceedings - 2016 9th International Symposium on Computational Intelligence and Design, ISCID 2016 | Year: 2017

With the development of computer network technology and popularization, and the technology of data acquisition, data management and data query develop rapidly. People who is in the surging "data ocean", need an intelligent technology badly, to "explore" more valuable "oil "from the "data ocean", so the data mining technology which has been successfully used in commercial, medical, financial, and other fields, emerges. The primary technology of data mining is classification analysis, cluster analysis, Association Rule analysis, and etc. Association Rule analysis is an important branch of data mining, which can extract the valuable associations or rules people want to know from data warehouse. Based on the background of "data platform for public petition", it aims to study how to combine the Association Rule analysis technology with the current massive government-data, extracting association information from the massive hidden government-data, which can provide userful and valuable information according to the practical significance of the associations for system managers and decision makers. This paper study the classic Association Rule algorithm Apriori, propose the improved Apriori algorithm based on matrix com-pression. Based on this improved Apriori algorithm, develop the module of the analysis of cases evaluation, which can associate the cases and case handlers according to the information of cases and case handlers fistly, and then get the practical significance from the association result analysis, which can provide help to the managers and decision makers. © 2016 IEEE.


Zhang Y.,University of Electronic Science and Technology of China
Proceedings - 2016 9th International Symposium on Computational Intelligence and Design, ISCID 2016 | Year: 2017

The super-resolution passive radar image can be obtained by estimation of signal parameter via rotational invariance technique (ESPRIT) method under the condition of small angular rotation. However, the ESPRIT method needs high signal noise ratio (SNR), which may not be satisfied in actual passive radar system. Therefore, a super-resolution passive inverse synthetic aperture radar (ISAR) imaging framework of moving targets using the relaxation (RELAX) algorithm is proposed under the condition of few illuminators of opportunity and small rotation angle with low SNR. During this framework, the RELAX model of passive radar imaging is mathematically established, and then we apply the RELAX algorithm to extract spatial frequencies and amplitudes of different scatterers on the target. Finally, the super-resolution passive ISAR image can be obtained by frequency searching. Comparing with existing super-resolution ESPRIT method, the proposed method can achieve a more robust reconstruction in low SNR case. © 2016 IEEE.


Wu S.,University of Electronic Science and Technology of China | Shu L.,University of Electronic Science and Technology of China
2016 3rd International Conference on Systems and Informatics, ICSAI 2016 | Year: 2016

One innovation of our paper lies in the introduction of neutral anticipated backward stochastic differential equations (NABSDEs). By the theorem of fixed point, we show that those equations have unique solutions. This type of equations can be regarded as an expansion of classical backward stochastic differential equations (BSDEs). On the other hand, we focus on the neutral systems' optimality problems and obtain a neutral maximum principle by virtue of NABSDEs and duality technique. © 2016 IEEE.


Zheng D.,University of Electronic Science and Technology of China | Zhang H.,University of Electronic Science and Technology of China
Proceedings - 2016 8th International Conference on Intelligent Human-Machine Systems and Cybernetics, IHMSC 2016 | Year: 2016

In this paper, the transformation of control protocols is researched among three kinds of cooperative control (consensus with no leader, tracking control with one leader, containment control with multiple leaders) for multi-agent systems. By the extension of local neighborhood synchronization error, the consensus problem, the tracking problem, and the containment problem are converted to the stability problem of the extended local neighborhood synchronization error. Some results of protocols transformation are present. The main contribution of this paper is not the design of a control protocol, but the result about the transformation of control protocols among consensus, tracking, and containment control, resulting to the cost reduction of the design of another control protocol. © 2016 IEEE.


Jiang T.,University of Electronic Science and Technology of China | Jiang T.,Chengdu Yosemite Ltd Corporation
Proceedings - 2016 8th International Conference on Intelligent Human-Machine Systems and Cybernetics, IHMSC 2016 | Year: 2016

Three dimensional data reconstruction and registration is essential in modern mechanism design and art entertainment, this paper proposed the key technologies of the black/white ring mark based 3D data registration when using monocular laser line scanning technology, including fast circle recognition, mapping circle centers matching between adjacent views, rigid transform matrix computing and 3D data registration, the real sculpture experiments show that the proposed method is successful and effective. © 2016 IEEE.


Kang X.,University of Electronic Science and Technology of China | Yang J.,Singapore Power Group
Computer Networks | Year: 2017

Effective in fighting against “free-riding” and stimulating the cooperation between peers, credit-based incentive mechanisms are widely adopted in today's peer-to-peer (P2P) streaming networks. This work considers a P2P multimedia streaming system that relies on credits for incentivizing peers to upload. The main problem of focus is to derive the optimal strategy for a peer, in terms of allocating its credits across different time slots, to maximize its long-term viewing experience. Especially, the dynamic changing feature of credits is taken into consideration when we formulate the problem, and the optimal credits allocation is shown to be a staircase-like function over time. Then, based on the characteristics of the optimal credits allocation strategy, an effective double-loop iterative algorithm is proposed. For the consideration of practical implementation, three low-complexity credits allocation strategies are proposed. It is shown that each of the strategies has its own feature and is suitable for a specific scenario. Then, as an extension, the proposed credits allocation schemes are reinvestigated for P2P streaming networks that adopt dynamic-pricing credits-based incentive mechanisms. It is shown that the previously obtained credits allocation strategies and algorithms can be easily applied to these systems with minor modifications. © 2017


Ding Y.,Southwest University of Science and Technology | Zhong S.,University of Electronic Science and Technology of China | Long S.,Chongqing University of Technology
International Journal of Robust and Nonlinear Control | Year: 2017

This paper investigates the problem of asymptotic stability in probability for singular stochastic systems with Markovian switchings. A stochastic Lyapunov theorem on asymptotic stability in probability for the considered systems is provided. Also, we show that the original system has the same stability property as its difference-algebraic form based on singular value decomposition. By utilizing the earlier results, a sufficient condition is obtained in terms of linear matrix inequalities, which is easy to check by using standard software. © 2017 John Wiley & Sons, Ltd.


Yao D.,University of Electronic Science and Technology of China
Brain Topography | Year: 2017

Currently, average reference is one of the most widely adopted references in EEG and ERP studies. The theoretical assumption is the surface potential integral of a volume conductor being zero, thus the average of scalp potential recordings might be an approximation of the theoretically desired zero reference. However, such a zero integral assumption has been proved only for a spherical surface. In this short communication, three counter-examples are given to show that the potential integral over the surface of a dipole in a volume conductor may not be zero. It depends on the shape of the conductor and the orientation of the dipole. This fact on one side means that average reference is not a theoretical ‘gold standard’ reference, and on the other side reminds us that the practical accuracy of average reference is not only determined by the well-known electrode array density and its coverage but also intrinsically by the head shape. It means that reference selection still is a fundamental problem to be fixed in various EEG and ERP studies. © 2017 The Author(s)


Zhang M.,University of Electronic Science and Technology of China | Zhang M.,Chinese Academy of Forestry | Wei X.,University of British Columbia | Li Q.,University of British Columbia
Ecohydrology | Year: 2017

Hydrological responses to forest disturbances are highly variable among watersheds. Climatic factors including water and energy are major drivers that determine the hydrological responses to forest disturbances. Although there are a number of large watershed studies on identifying the role of climate in the hydrological response to forest disturbances (e.g., logging, insect infestation, and fire), they are mainly concentrated on the precipitation effect. Given that climatic factors including both water and energy interact dynamically with hydrology and forest, and accordingly with forest–water relationships, there is a need for understanding the joint controls of water and energy on hydrological responses to forest changes by use of an integrated climatic index. In this study, 6 large watersheds along climatic gradients (Willow, Cottonwood, Baker, Moffat, Tulameen, and Ashnola) in the interior of British Columbia (BC), Canada, were selected for investigating the effect of climate on hydrological responses to forest disturbances at a large watershed scale by using modified double mass curves and statistical analysis (time series cross-correlation, linear regression, and Mann–Whitney U test). Key results include the following: (a) in watersheds with a cumulative equivalent clear-cut area of over 30% (Willow, Baker, Moffat, and Tulameen), mean annual flows were significantly increased by about 21–60 mm due to cumulated forest disturbances and (b) mean annual flow response to forest disturbances varied along climatic gradient. The amount of mean annual flow increase due to forest disturbances in energy-limited watersheds Willow and Tulameen was as 3 times as that in water-limited watersheds Baker and Moffat. Similarly, mean annual flow changes due to forest disturbances in wetter years were greater than those in drier years as suggested by results from the study watersheds. These findings highlight the need to develop different strategies for forests management in water-limited and energy-limited watersheds to minimize or adapt hydrological changes due to forest disturbances. Copyright © 2017 John Wiley & Sons, Ltd.


Guo H.,University of Electronic Science and Technology of China | Xi L.,University of Electronic Science and Technology of China
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

With the rapid development of photoacoustic imaging, it has been widely used in various research fields such as biology, medicine and nanotechnology. Due to the huge difference among photoacoustic imaging systems, it is hard to integrate them in one platform. To solve this problem, we propose to develop a new universal photoacoustic imaging platform that integrates acoustic-resolution photoacoustic microscopy and optical-resolution photoacoustic microscopy through a multifunctional liquid lens. This lens takes advantage of an inherently low acoustic impedance and a tunable focal length that was characterized by the infusion volume of the liquid. In this paper, the liquid lens was used to realize confocal of laser illumination and acoustic detection for both acoustic-resolution and optical-resolution photoacoustic microscopy. The home-made polyvinylidene fluoride (PVDF) acoustic transducer had a center frequency of 10MHz and -6dB frequency spectrum from 4MHz to 15MHz which yielded to an axial resolution of 70 μm. The lateral resolutions of acoustic- and optical-resolution photoacoustic microscopy were evaluated to be 180 μm and 4.8 μm, respectively. The vasculature of rat ears was carried out to evaluate the performance of optical-resolution photoacoustic microscopy. © 2016 SPIE.


Qi W.,University of Electronic Science and Technology of China | Xi L.,University of Electronic Science and Technology of China
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Optical resolution photoacoustic microscopy (ORPAM) is currently one of the fastest evolving photoacoustic imaging modalities. It has a comparable spatial resolution to pure optical microscopic techniques such as epifluorescence microscopy, confocal microscopy, and two-photon microscopy, but also owns a deeper penetration depth. In this paper, we report a rotary-scanning (RS)-ORPAM that utilizes a galvanometer scanner integrated with objective to achieve rotary laser scanning. A 15 MHz cylindrically focused ultrasonic transducer is mounted onto a motorized rotation stage to follow optical scanning traces synchronously. To minimize the loss of signal to noise ratio, the acoustic focus is precisely adjusted to reach confocal with optical focus. Black tapes and carbon fibers are firstly imaged to evaluate the performance of the system, and then in vivo imaging of vasculature networks inside the ears and brains of mice is demonstrated using this system. © 2016 SPIE.


Tang H.,University of Electronic Science and Technology of China | Nie Z.,University of Electronic Science and Technology of China
ISAPE 2016 - Proceedings of the 11th International Symposium on Antennas, Propagation and EM Theory | Year: 2016

Focusing on the design of the large number of antennas in massive multiple input multiple output (MIMO), this paper has proposed a configuration of the antennas for massive MIMO, and presented a possible working model based on the idea of dynamic combination of the multiple antennas and the antenna arrays. The upper limit of the number of antenna elements for beamforming in the massive MIMO system is studied. Then the zero-forcing (ZF) precoding and quaternary phase-shift keying (QPSK) modulation are applied to evaluate bit error rate (BER) of the proposed configuration. Finally, the simulation results have been given to show the performance of the configuration and the working model proposed in this paper. © 2016 IEEE.


Huang N.,University of Electronic Science and Technology of China | Xi L.,University of Electronic Science and Technology of China
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Zebrafish is a top vertebrate model to study developmental biology and genetics, and it is becoming increasingly popular for studying human diseases due to its high genome similarity to that of humans and the optical transparency in embryonic stages. However, it becomes difficult for pure optical imaging techniques to volumetric visualize the internal organs and structures of wild-type zebrafish in juvenile and adult stages with excellent resolution and penetration depth. Even with the establishment of mutant lines which remain transparent over the life cycle, it is still a challenge for pure optical imaging modalities to image the whole body of adult zebrafish with micro-scale resolution. However, the method called photoacoustic imaging that combines all the advantages of the optical imaging and ultrasonic imaging provides a new way to image the whole body of the zebrafish. In this work, we developed a non-invasive photoacoustic imaging system with optimized near-infrared illumination and cylindrical scanning to image the zebrafish. The lateral and axial resolution yield to 80 μm and 600 μm, respectively. Multispectral strategy with wavelengths from 690 nm to 930 nm was employed to image various organs inside the zebrafish. From the reconstructed images, most major organs and structures inside the body can be precisely imaged. Quantitative and statistical analysis of absorption for organs under illumination with different wavelengths were carried out. © 2016 SPIE.


Huang X.,University of Electronic Science and Technology of China | Pan J.,University of Electronic Science and Technology of China
ISAPE 2016 - Proceedings of the 11th International Symposium on Antennas, Propagation and EM Theory | Year: 2016

A low profile quadrifilar helix antenna based on top-loaded technology for global navigation satellite system is presented in this paper. The top-loaded technology can both be used to reduce the profile of the wire form quadrifilar helix antenna and the printed form. An S-band top-loaded quadrifilar helix antenna has been simulated and possesses the characteristic of wide beam width, high gain at the low elevation, good circular polarization performance and the low profile. This low profile antenna can be an attractive candidate for handset applications. © 2016 IEEE.


Wang J.,University of Electronic Science and Technology of China | Cheng Y.J.,University of Electronic Science and Technology of China
APCAP 2016 - 2016 IEEE 5th Asia-Pacific Conference on Antennas and Propagation, Conference Proceedings | Year: 2016

In this paper, a 92∼94 GHz low sidelobe level (SLL) and high gain slot antenna array based on the substrate integrated waveguide (SIW) technology is presented. The antenna includes two SIW 16×16 arrays, which are placed back-to-back, and a waveguide divider. The aperture size of the antenna is 34×90 mm2. Simulated and measured results show that the return loss is larger than 10dB, and the SLLs in both E-plane and H-plane are under-20dB. The measured results are in good agreement with the simulated ones. © 2016 IEEE.


Wu Y.,University of Electronic Science and Technology of China | Arslanagic S.,Technical University of Denmark
APCAP 2016 - 2016 IEEE 5th Asia-Pacific Conference on Antennas and Propagation, Conference Proceedings | Year: 2016

The multi-layer two-dimensional(2-D) epsilon-negative (ENG), mu-negative (MNG) and double-negative (DNG) materials are investigated in this work. The unit cells consist of infinite dielectric cylinders of which the size and permittivity are chosen to excite the dominant electric and magnetic dipole modes inside the structure. This enables the ENG, MNG, and DNG behaviors. The material parameters are obtained from the simulated S-parameters by use of the Nicholson-Ross-Weir method. For the 2-layer structure in particular, the results show a possibility of DNG realization with a negative refractive index from 303MHz to 305MHz. © 2016 IEEE.


Mao S.,University of Electronic Science and Technology of China | Xiong J.,University of Electronic Science and Technology of China
APCAP 2016 - 2016 IEEE 5th Asia-Pacific Conference on Antennas and Propagation, Conference Proceedings | Year: 2016

The aperture radiation of TEM mode waveguide of two different sizes has been studied. Simulated results show that when the aperture is covered with an effective bulk epsilon-near-zero (ENZ) metamaterial block with the component along the normal of the aperture of the permittivity tensor approaching zero, the beamwidth of the E-plane can be significantly reduced. The effective bulk ENZ block has been implemented by the electric-LC-resonator (ELC) array as well. © 2016 IEEE.


You Q.,University of Electronic Science and Technology of China | Wan Q.,University of Electronic Science and Technology of China
Information (Switzerland) | Year: 2017

In this paper, we address strongly convex programming for principal component analysis, which recovers a target matrix that is a superposition of low-complexity structures from a small set of linear measurements. In this paper, we firstly provide sufficient conditions under which the strongly convex models lead to the exact low-rank matrix recovery. Secondly, we also give suggestions that will guide us how to choose suitable parameters in practical algorithms. Finally, the proposed result is extended to the principal component pursuit with reduced linear measurements and we provide numerical experiments.


Liang D.,University of Electronic Science and Technology of China | Xu Z.,University of Sichuan | Liu D.,Southwest Jiaotong University
Information Sciences | Year: 2017

Three-way decisions with decision-theoretic rough sets (DTRSs) as a typical risk decision method, are generated by Bayesian decision theory and have three kinds of decision strategies, i.e., the acceptance decision, the deferment (non-commitment) decision and the rejection decision. The construction of three-way decisions under the complex decision-making context creates enormous challenges. The determination of loss function is one of key steps. In this paper, we discuss the decision principles of three-way decision rules based on the variation of loss functions with intuitionistic fuzzy sets (IFSs). More specifically, we introduce the intuitionistic fuzzy point operator (IFPO) into DTRSs and explore three-way decisions. Firstly, we construct a loss function matrix with the point operator and analyze its corresponding properties. IFPO implies one type of variation modes for the loss functions of three-way decisions. With respect to the point operator, we show that the prerequisites among loss functions still hold in each stage. Secondly, given the loss functions, we construct the corresponding three-way decision model and deduce three-way decisions. Finally, with the aid of information entropy theory, we further investigate which stage may be most suitable to make the decision. This study extends the range of applications of three-way decisions to the new intuitionistic fuzzy environment. © 2016 Elsevier Inc.


Fan S.,University of Electronic Science and Technology of China | Chi W.,University of Electronic Science and Technology of China
Briefings in Functional Genomics | Year: 2016

Aberrant DNA methylation is considered to be one of themost common hallmarks of cancer. Several recent advances in assessing the DNA methylome provide great promise for deciphering the cancer-specific DNAmethylation patterns. Herein, we present the current key technologies used to detect high-throughput genome-wide DNAmethylation, and the available cancerassociatedmethylation databases. Additionally, we focus on the computationalmethods for preprocessing, analyzing and interpreting the cancermethylome data. It not only discusses the challenges of the differentiallymethylated region calling and the predictionmodel construction but also highlights the biomarker investigation for cancer diagnosis, prognosis and response to treatment. Finally, some emerging challenges in the computational analysis of cancermethylome data are summarized. © The Author 2016. Published by Oxford University Press.


Gao C.,University of Electronic Science and Technology of China | Li X.,University of Electronic Science and Technology of China
Optical Review | Year: 2017

Both experimental results and empirical research have shown that the atmospheric turbulence can present the anisotropic property not only at a few meters above the ground but also at high altitudes of up to several kilometers. This paper investigates the modulation transfer function of a Gaussian beam propagating along a horizontal path in weak anisotropic non-Kolmogorov turbulence. Mathematical expressions are obtained based on the generalized exponential spectrum for anisotropic turbulence, which includes the spectral power law value, the finite inner and outer scales of turbulence, the anisotropic factor, and other essential optical parameters of the Gaussian beam. The numerical results indicate that the atmospheric turbulence would produce less negative effects on the wireless optical communication system with an increase in the anisotropic factor. © 2017 The Optical Society of Japan


He G.,University of Electronic Science and Technology of China | Yang L.,University of Electronic Science and Technology of China
Proceedings - 2016 9th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics, CISP-BMEI 2016 | Year: 2016

The development of image processing methods based on partial differential equations, such as denoising, restoration, segmentation and so on, is an emerging field in the last decade, where a large number of models are second order nonlinear diffusion equations. In this article, we present a two level finite volume method to solve the Perona and Malik (P-M) equation. The method involves solving one small implicit Perona and Malik problem on the coarse mesh system, and an explicit Perona and Malik problem on the fine mesh. The numerical results demonstrate that the two level method is efficient and can save a large amount of computational time than the standard FVM method. © 2016 IEEE.


Widaa A.H.A.,University of Electronic Science and Technology of China | Talha W.A.,University of Gezira
Proceedings - 2017 International Conference on Communication, Control, Computing and Electronics Engineering, ICCCCEE 2017 | Year: 2017

Since the 20th century industrial revolution era, automobiles started playing a key and important role in our daily life activities. But, unfortunately, at the same time, an automobiles related accidents, and problems are representing an increasing source of danger on Human's life. In this paper a design of an autonomous (self-driving) car control system is presented to reduce automobiles-related problems. System's design is done by using Fuzzy Logic Control technology in addition to artificial intelligence algorithms. The achieved results demonstrates that proposed design has shown a reliable and efficient performance; all of the main driving control tasks (speed, brakes, steering wheel) were done effectively; it acts just same as a professional human driver. © 2017 IEEE.


Zhong Y.C.,University of Electronic Science and Technology of China | Cheng Y.J.,University of Electronic Science and Technology of China
European Microwave Week 2016: "Microwaves Everywhere", EuMW 2016 - Conference Proceedings; 46th European Microwave Conference, EuMC 2016 | Year: 2016

A wideband pseudo-Bessel beam antenna with a large non-diffraction range is proposed in this paper. A phase shift surface (PSS) with controllable phase shift versus frequency response is employed. Thus, the Bessel beam can be realized over a wideband. Measurement indicates that the relative bandwidth of the Bessel beam antenna is more than 13.7% at Ka-band and the non-diffraction range is more than 150 times of the wavelength at the center frequency of 29 GHz. Good axial symmetry can be achieved because both cellular topology and hexagonal element are used. © 2016 EuMA.


Wu Z.,University of Electronic Science and Technology of China | Hu H.,Huawei
IEEE Region 10 Annual International Conference, Proceedings/TENCON | Year: 2017

Video quality assessment is one of the key techniques in video communication and editing. With constraints of transmission system, storage space etc., original information of videos may not be available. No-reference video quality assessment (NRVQA) methods are in demand. This paper presents a reconstruction-based no-reference video objective quality assessment algorithm for quantization distorted video frames. The proposed assessment is performed without any prior information of distortion or codec parameters. By deeply mining the features of the testing frames, the proposed algorithm can reconstruct zero coefficients' values in every sub-band of frequency coefficients. In addition, non-zero frequency coefficients error will be estimated more accurately with the proposed modified DCT coefficients distribution model. To fully evaluate the proposed NRVQA algorithm, testing video frames are distorted with various quantization steps blindly. Experimental results have showed that the proposed reconstruction-based NRVQA algorithm can give out pleasant performances compared with the state of the art NRVQA algorithms. © 2016 IEEE.


Wu Z.,University of Electronic Science and Technology of China | Hu H.,Hua Wei Technologies Co.
IEEE Region 10 Annual International Conference, Proceedings/TENCON | Year: 2017

With consideration of human visual perception, the structural similarity (SSIM) index has presented a pleasant prediction for video quality assessment in many applications such as video editing and network visual communications. However, SSIM is not implementable in real world applications like IPTV or broadcasting services, which need full access to the original video frames. In this paper we propose a no-reference approach to estimate SSIM without only information of the original video frames. We analysis quantization distortion's affections in video frames' statistical properties and then develop a self-training-based approach to estimate the quantized frames' SSIM. We find an interesting result that the statistical characteristics of test frame can be well estimated by itself and some set of its self-quantized frames. A self-training method is applied to find the optimal quantization step sets for estimation processing. There is no other information requirement in the proposed no-reference SSIM estimation method except the test frame itself. The standard video sequences are taken to evaluate the proposed self-training-based no-reference assessment estimation approach. Experimental results have shown that the proposed approach can give out perfect estimation accuracy and strong consistency with SSIM and subjective evaluations. © 2016 IEEE.


Zhang M.,University of Electronic Science and Technology of China | He J.,University of Electronic Science and Technology of China
Proceedings - 2016 9th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics, CISP-BMEI 2016 | Year: 2016

Fault-tolerant mechanisms have been an essential part of electronic equipments in extreme environments these years. The combined analog circuit system can work properly when one or several parts of it break down. Then, what factors affect the fault-tolerant performance of such systems? System function is the most direct reflection of the output of a circuit, it can necessarily give us much useful information. From the perspective of vectors,this paper analyzed the phase angle of the combined circuit system based on system functions and furthermore inferred the relation between angle and fault-tolerant abilities. Experimental results show that, the larger angle a combined circuit system has, the better its fault-tolerant performance is, which will provide great benefit for designing analog circuit with better fault tolerance. © 2016 IEEE.


Gao S.,University of Electronic Science and Technology of China | Xue R.,University of Electronic Science and Technology of China
Proceedings - 15th IEEE International Conference on Trust, Security and Privacy in Computing and Communications, 10th IEEE International Conference on Big Data Science and Engineering and 14th IEEE International Symposium on Parallel and Distributed Processing with Applications, IEEE TrustCom/BigDataSE/ISPA 2016 | Year: 2016

Locality-aware task scheduling for MapReduce can reduce job execution time by avoiding data transferring. However, many existing scheduling algorithms suffer from either heavy storage overhead, reduced task parallelism, significant response time, or poor scalability. To address these issues, this paper presents BOLAS+, a scalable lightweight locality-aware scheduling algorithm for Hadoop. BOLAS+ takes such global information as block distribution and node performance divergence into consideration for optimal scheduling. BOLAS+ associates each node and each block replica with a value, node importance, and replica priority, respectively. As the only factors for scheduling decision-making, these two values are updated dynamically upon a scheduling request, and are designed in a way that they can be calculated very efficiently. Only simple comparisons within these values of local blocks are involved during scheduling, which guarantees the scalability of BOLAS+. Experimental results show that BOLAS+ can completely eliminate off-switch scheduling, and ensure more than 95% node-local scheduling with a very low complexity O(n/m), which in turn can reduce the total job execution time by up to 15.1%. © 2016 IEEE.


Yang G.,University of Electronic Science and Technology of China | Liang Y.-C.,University of Electronic Science and Technology of China
2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings | Year: 2016

Ambient backscatter communications (AmBC) enables radio-frequency (RF) powered devices (e.g., tags, sensors) to modulate their information bits over ambient RF carriers in an over-the-air manner. This system, called ''modulation in the air'', thus has emerged as a promising technology for green communications and future Internet-of-Things. This paper studies the AmBC system over ambient orthogonal frequency division multiplexing (OFDM) carriers in the air. We first establish the system model for such AmBC system from spread-spectrum perspective, from which a novel joint design for tag waveform and reader detector is proposed. We construct the test statistic that cancels out the direct-link interference by exploiting the repeating structure of the ambient OFDM signals due to the use of cyclic prefix. The maximum-likelihood detector is proposed to recover the tag bits, for which the optimal threshold is obtained with closed-form expression. Also, we analyze the effect of various system parameters on the transmission rate and detection performance. Finally, extensive numerical results show that the proposed transceiver design outperforms the conventional design. © 2016 IEEE.


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.


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.


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.


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.


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.


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


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

We consider a broadcast channel with three receivers and three-degraded message sets, i.e., the transmitter has a common message intended for all three receivers, a message intended for receivers 2 and 3, and a private message intended only for receiver 3. The messages are transmitted over a family of parallel degraded broadcast channels. In the most general case, the broadcast channel consists of the product of six parallel degraded broadcast channels, each with a different order of degradedness. We first consider an achievable rate region of Nair and El Gamal, by appropriately choosing independent input random variables and auxiliary random variables for each subchannel. We then show that the achievable rate region attains the capacity region for two different classes of such broadcast channels, one consisting of the product of five parallel degraded broadcast channels and another consisting of the product of three parallel degraded broadcast channels. To accomplish this, we make use of an information-theoretic inequality that may be proven using the Csiszar-sum identity. Next, we extend the result to the Gaussian case. We consider the aligned Gaussian MIMO broadcast channel consisting of the product of six parallel degraded Gaussian broadcast channels, where the Gaussian noise vectors for each of the users in each of the subchannels follow a degradedness order, i.e., the noise covariance matrices may be ordered in a positive semi-definite sense. We show that the Nair-El Gamal achievable rate region considered in this paper is maximized by Gaussian inputs. To prove that Gaussian inputs are optimal, we prove an extremal entropy inequality employing a new method recently introduced by Geng and Nair to prove the capacity region of the two-user Gaussian MIMO broadcast channel with common and private messages. © 1963-2012 IEEE.


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

The heterogeneous network (HetNet) architecture, device-to-device (D2D) communications, and coexistence with existing wireless systems have been regarded as new communication paradigms introduced in LTE-A/LTE-B cellular networks. To facilitate these paradigms, considerable research has shown promise of the cognitive radio (CR) technology, particularly the cognitive radio resource management (CRRM) on the top of resource allocation to control Layer-1 and Layer-2 radio operations, thus eliminating the concerns of potential system impacts and operation unreliability to bridge the gap between cellular and CR technologies. To support diverse communication paradigms with different challenges, a variety of CRRM schemes have been recently proposed, which however significantly perplexes the system implementation. To provide a general reconfigurable framework, in this article, we reveal a software-defined design of the CRRM. Through proper configurations, this software- defined design is able to adapt to diverse communication paradigms in LTE-A/LTE-B, and provides transmission reliability in terms of quality- of-service guarantees via the optimum control of the design. Supporting diverse CRRM schemes, this design substantially simplifies the system realization to bring the development of the CRRM to the next stage of practice for the fifth generation (5G) cellular network. © 2002-2012 IEEE.


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.
Advanced Materials | Year: 2011

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.


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.


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 |