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Progress in Natural Science:Materials International 2007年第6期17卷 681-686页

作者： Zhou Zhiheng, Zeng Delu and Xie Shengli(college of electronic & information engineering, South china University of Technology, Guangzhou 510640, china) college of electronic & information engineering South China University of Technology Guangzhou 510640 China

For the contours extraction from the images, active contour model and self-organizing map based approach are popular nowadays. but they are still confronted with the problems that the optimization of energy function will trap in local minimums and the contour evolutions greatly depend on the initial contour selection. Addressing to these problems, a contours extraction algorithm based on RbF neural network is proposed here. A series of circles with adaptive radius and center is firstly used to search image feature points that are scattered enough. After the feature points are clustered, a group of radial basis functions are constructed. Using the pixels’ intensities and gradients as the input vector, the final object contour can be obtained by the predicting ability of the neural network. The RbF neural network based algorithm is tested on three kinds of images, such as changing topology, complicated background, and blurring or noisy boundary. Simulation results show that the proposed algorithm performs contours extraction greatly.

关键词： contours extraction RbF neural network dynamic clustering.

Vector bundle constraint for particle swarm optimization and its application to active contour modeling

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Progress in Natural Science:Materials International 2007年第10期17卷 1220-1225页

作者： Zeng Delu, Zhou Zhiheng and Xie Shengli(college of electronic and information engineering, South china University of Technology, Guangzhou 510641, china) college of electronic and information engineering South China University of Technology Guangzhou 510641 China

Active contour modeling (ACM) has been shown to be a powerful method in object boundary extraction. In this paper, a new ACM based on vector bundle constraint for particle swarm optimization (VbCPSO-ACM) is proposed. Different from the traditional particle swarm optimization (PSO), in the process of velocity update, a vector bundle is predefined for each particle and velocity update of the particle is restricted to its bundle. Applying this idea to ACM, control points on the contour are treated as particles in PSO and the evolution of the contour is driven by the particles. Meanwhile, global searching is shifted to local searching in ACM by decreasing the number of neighbors and inertia. In addition, the addition and deletion of particles on the active contour make this new model possible for representing the real boundaries more precisely. The proposed VbCPSO-ACM can avoid self-intersection during contour evolving and also extract inhomogeneous boundaries. The simulation results proved its great performance in performing contour extraction.

关键词： boundary extraction active contour modeling particle swarm optimization velocity update vector bundle.

Approximately optimal tracking control for discrete time-delay systems with disturbances

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Progress in Natural Science:Materials International 2008年第2期18卷 225-231页

作者： Gongyou Tang a,,Huiying Sun b,Haiping Pang c a college of information Science and engineering,Ocean University of china,Qingdao 266100,china b college of information and Electrical engineering,Shandong University of Science and Technology,Qingdao 266510,china c college of Automation and electronic engineering,Qingdao University of Science and Technology,Qingdao 266042,china college of information Science and engineering Ocean University of China Qingdao 266100 China college of information and Electrical engineering Shandong University of Science and Technology Qingdao 266510 China college of Automation and electronic engineering Qingdao University of Science and Technology Qingdao 266042 China

Optimal tracking control (OTC) for discrete time-delay systems affected by persistent disturbances with quadratic performance index is considered. by introducing a sensitivity parameter,the original OTC problem is transformed into a series of two-point boundary value (TPbV) problems without time-advance or time-delay terms. The obtained OTC law consists of analytic feedforward and feedback terms and a compensation term which is the sum of an infinite series of adjoint vectors. The analytic feedforward and feedback terms can be found by solving a Riccati matrix equation and two Stein matrix equations. The compensation term can be obtained by using an iteration formula of the adjoint vectors. Observers are constructed to make the approximate OTC law physically realizable. A simulation example shows that the approximate approach is effective in tracking the reference input and robust with respect to exogenous persistent disturbances.

关键词： Discrete systems Time-delay systems Disturbances Optimal control Tracking control

Series-based approximate approach of optimal tracking control for nonlinear systems with time-delay

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Progress in Natural Science:Materials International 2008年第12期18卷 1571-1576页

作者： Gongyou Tang~a Mingqu Fan~(a,b) a college of information Science and engineering,Ocean University of china,Qingdao 266100,china b college of information and engineering,Shandong University of Science and Technology,Jinan 250031,china college of information Science and engineering Ocean University of China Qingdao 266100 China college of information and engineering Shandong University of Science and Technology Jinan 250031 China

The optimal output tracking control (OTC) problem for nonlinear systems with time-delay is *** a series-based approx- imate approach,the original OTC problem is transformed into iteration solving linear two-point boundary value problems without time- *** OTC law obtained consists of analytical linear feedback and feedforward terms and a nonlinear compensation term with an infinite series of the adjoint *** truncating a finite sum of the adjoint vector series,an approximate optimal tracking control law is obtained.A reduced-order reference input observer is constructed to make the feedforward term physically *** exam- ples are used to test the validity of the series-based approximate approach.

关键词： Nonlinear systems Time-delay Tracking control Optimal control Observer

Improving TCP Performance over Wireless Links Using Link-Layer Retransmission and Explicit Loss Notification

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Journal of Systems engineering and electronics 2002年第4期13卷 17-23页

作者： Zhou Zhizhao & Han Zhengzhi college of electronic and information engineering, Shanghai Jiaotong University, Shanghai 200030, P. R. china college of electronic and information engineering Shanghai Jiaotong University Shanghai 200030 P. R. China

In order to support the mobility of computers during communication, the transport control protocol (TCP) connections between fixed host and mobile host often traverse wired and wireless networks, and the recovery of the losses due to wireless transmission error is much different from congestion control. This paper analyzes the interaction between TCP and link layer retransmission scheme when the correlated packet are losses handled, indicates that a higher value of the maximum number of successive link layer timeout retransmissions has an adverse effect on TCP ability to perform congestion control rapidly. To achieve a better TCP performance, the paper proposes a strategy combining link-layer selective-reject automatic repeat request (ARQ) with explicit loss notification mechanism, which can respond to congestion quickly while keeping wireless link more reliable, and make TCP react to the different packet losses more suitably.

关键词： Congestion control (communication) Mechanisms Performance Transmissions

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Performance of iteratively decoded bit-interleaved coded modulation with chaos based interleaving strategies

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Science china(information Sciences) 2010年第4期53卷 833-841页

作者： ZOU XueLan1*, LIU WeiYan2 & FENG GuangZeng3 1Department of electronic and information engineering, Zhejiang Institute of Media and Communications, Hangzhou 310018, china 2Department of information engineering, Jiangsu City Vocation college, Nanjing 210036, china 3college of Communication and information engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, china Department of electronic and information engineering Zhejiang Institute of Media and Communications Hangzhou China Department of information engineering Jiangsu City Vocation College Nanjing China college of Communication and information engineering Nanjing University of Posts and Telecommunications Nanjing China

bit-interleaved coded modulation with iterative decoding (bICM-ID) is a bandwidth efficient trans- mission scheme which is well suitable for next-generation mobile communications. The interleaver design is critical to the high performance of bICM-ID. In this paper we investigate the application of the chaos theory to the interleaver design to further improve the performance of bICM-ID. A new interleaving scheme based on the chaos theory is proposed. Compared with the random interleaver, the proposed approach has the ad- vantages including lower system delay and higher transmission efficiency. Simulation results in both additive white Gaussian noise (AWGN) channel and Rayleigh fading channel are provided, which demonstrates that the new interleaver is better than the random interleaver and exhibits excellent performance when applied to the bICM-ID system.

关键词： chaos interleaving bit-interleaved coded modulation (bICM) iterative decoding

Research progress on electrical signals in higher plants

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Progress in Natural Science:Materials International 2009年第5期19卷 531-541页

作者： Xiaofei Yana, Zhongyi Wang a, Lan Huang a, Cheng Wang b, Ruifeng Hou b, Zhilong Xu b, Xiaojun Qiao b a college of information and Electrical engineering, china Agricultural University, beijing 100083, china b National engineering Research Center for information Technology in Agriculture, beijing 100097, china college of information and Electrical engineering China Agricultural University Beijing 100083 China National engineering Research Center for information Technology in Agriculture Beijing 100097 China

This review introduces the characteristics of electrical signals in higher plants and their corresponding physiological significance, and describes in detail the impact of environmental factors (e.g. light and temperature) on the electrical potential of the plants. Also, we evaluate the measurement techniques used for electrical signals in plants, including intracellular measurement, extracellular measurement, measurement of the ion channel based on the patch-clamp technique and on the non-invasive microelectrode vibrating probe technique. We also give a brief review of the applications of these methods for investigating electrical signals in plants. The ionic mechanism of electrical activity in plants is then discussed in terms of environmental response in higher plants, and this is used to provide a theoretical basis for quantitative description of the electrical signals in plants. A model for interpretation of the electrical signal mechanisms in higher plants is discussed, but further experiments are required for the verification of this model.

关键词： Ion channel Temperature-induced Light-induced Ion mechanism Measurement technology

Single-channel blind separation of overlapped multicomponents based on energy operator

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Science china(information Sciences) 2010年第1期53卷 147-157页

作者： CAI QuanWei, WEI Ping & XIAO XianCi college of electronic engineering, University of electronic Science and Technology of china, Chengdu 610054, china college of electronic engineering University of Electronic Science and Technology of China Chengdu China

A method utilizing single channel recordings to blind separate the multicomponents overlapped in both time and frequency domains is proposed in this paper. The main idea of the method is based on using the energy operator and differential energy operator to estimate instantaneous frequencies and amplitudes of each component and then to reconstruct these components. This method, due to the good time resolution of the energy operator and differential energy operator, as well as the very low computational complexity, is very useful in real time processing and practical applications. Simulation results demonstrated the effciency of this method.

关键词： single channel time frequency overlap multicomponents separation energy operator differential energy operator

Large eddies induced by local impulse at wall of boundary layer with pressure gradients

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Progress in Natural Science:Materials International 2008年第7期18卷 873-878页

作者： Changgen Lu a,b,*, Weidong Caob, Yanmei Zhang b, Jintao Pengb a college of Atmospheric Science, Nanjing University of information Science & Technology, Nanjing 210044, china b college of Environmental Science and engineering, Hohai University, Nanjing 210098, china college of Atmospheric Science Nanjing University of Information Science & Technology Nanjing 210044 China college of Environmental Science and engineering Hohai University Nanjing 210098 China

Large eddies induced by local impulse at the wall with pressure gradients in the boundary layer was studied by direct numerical sim- ulations. The results show that the amplitude evolution, the high and low speed stripes, the formation of streamwise vortices, the ejection and sweeping, inflexions and distortion at the mean velocity profiles, as well as other characteristics, are consistent with the experimental and other numerical results. It is also found that large eddies are easy to be excited with adverse pressure gradient in the boundary layer, and the growth of amplitudes, formation of streamwise vortices and the influencing area etc., are much larger than those with favorable pressure gradient in the boundary layer. In contrast, large eddies are hardly to be induced through local impulse disturbance at the wall with favorable pressure gradients in the boundary layer.

关键词： boundary layer Pressure gradients Impulse Large eddies