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24 December 2007, Volume 18 Issue 4
New multi-layer data correlation algorithm for multi-passive-sensor location system
Zhou Li, Li Lingyun & He You
2007, 18(4):  667-672. 
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Under the scenario of dense targets in clutter, a multi-layer optimal data correlation algorithm is proposed. This algorithm eliminates a large number of false location points from the assignment process by rough correlations before we calculate the correlation cost, so it avoids the operations for the target state estimate and the calculation of the correlation cost for the false correlation sets. In the meantime, with the elimination of these points in the rough correlation, the disturbance from the false correlations in the assignment process is decreased, so the data correlation accuracy is improved correspondingly. Complexity analyses of the new multi-layer optimal algorithm and the traditional optimal assignment algorithm are given. Simulation results show that the new algorithm is feasible and effective.

Characterizing Ultra-wide Band indoor line-of-sight wireless channel
Wang Yang, Zhang Naitong, Zhang Qinyu & Zhang Zhongzhao
2007, 18(4):  673-678. 
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By exploring the deterministic characteristics of the measurement data, a new propagation model with two deterministic clusters and stochastic arriving rays within each cluster is proposed. When considering the cumulative distribution function (CDF) of the three key channel statistics, the proposed model fits the measurement data better than SV/IEEE 802.15.3, a model which is known as a standard model for UWB indoor propagation channel. Therefore, with the additional knowledge of the specific environment geometry, the proposed model generating impulse responses \resemble" the measured channel impulse responses better than IEEE model. Moreover, the proposed model's parameters obtaining procedure is simplified by utilizing simple parameters of the environment.

Analysis of wire antennas mounted on large perfectly conducting platforms using MLFMA
Que Xiaofeng & Nie Zaiping
2007, 18(4):  679-684. 
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The electric eld integral equation (EFIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze the radiation and impedance properties of wire antennas mounted on complex conducting platforms to realize fast, accurate solutions. Wire, surface and junction basis functions are used to model the current distribution on the object. Application of MLFMA reduces memory requirement and computing time compared to conventional methods, such as method of moment (MOM), especially for the antenna on a large-sized platform. Generalized minimal residual (GMRES) solver with incomplete LU factorization preconditioner using a dual dropping strategy (ILUT) is applied to reduce the iterative number. Several typical numerical examples are presented to validate this algorithm and show the accuracy and computational eciency.

Simulation research on scattering characteristics by complex targets
Guo Kunyi & Sheng Xinqing
2007, 18(4):  685-691. 
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A simulation approach based on a full-wave numerical method is presented to study electromagnetic characteristics by complex targets. How to validate simulation results is considered thoroughly under no analytical and measured data, where a double-check criterion is designed for our simulation approach. As an example, the scattering of F-117A is studied by using our simulation approach under all polarizations, di erent frequency bands, incident and scattering directions, etc., some of which, such as cross-polarization, bistatic RCS, have not been considered in the previous literature.

Blind channel estimation for redundant precoded OFDM systems
Liang Yongming, Luo Hanwen, Wu Yadong & Huang Jianguo
2007, 18(4):  692-697. 
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Considering that channel estimation can play a crucial role in coherent detection of the information symbols in each data block, a blind channel estimation approach is proposed for redundant precoded orthogonal frequency-division multiplexing (OFDM) systems. A redundant linear frequency-domain precoder is applied to each pair of blocks before they enter the OFDM system. Because of the introduced structure, the frequency-selective channel can be identified at the receiver based on autocorrelation operations, singular value decomposition (SVD), and by resolving the scalar ambiguity. The proposed channel estimation method has low computational complexity and requires no prior statistical information on channel or noise. And the proposed blind method has high spectral efficiency owing to exploiting no training sequence. Computer simulations confirm that this proposed blind channel estimation method can identify the frequency-selective channels perfectly and obtain a good performance.

New chaos-based encryption scheme for digital sequence
Zhang Zhengwei, Fan Yangyu & Zeng Li
2007, 18(4):  698-703. 
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To enhance the anti-breaking performance of privacy information, this article proposes a new encryption method utilizing the leaping peculiarity of the periodic orbits of chaos systems. This method maps the secret sequence to several chaos periodic orbits, and a short sequence obtained by evolving the system parameters of the periodic orbits in another nonlinear system will be the key to reconstruct these periodic orbits. In the decryption end, the shadowing method of chaos trajectory based on the modified Newton-Raphson algorithm is adopted to restore these system parameters. Through deciding which orbit each pair coordinate falls on, the original digital sequence can be decrypted.

Joint estimation of DOA, frequency, and polarization based on cumulants and UCA
Huang Jiacai, Shi Yaowu & Tao Jianwu
2007, 18(4):  704-709. 
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A joint estimation algorithm of direction of arrival (DOA), frequency, and polarization, based on fourth-order cumulants and uniform circular array (UCA) of trimmed vector sensors is presented for narrowband non-Gaussian signals. The proposed approach, which is suitable for applications in arbitrary Gaussian noise environments, gives a closed-form representation of the estimated parameters, without spectral peak searching. An efficient method is also provided for elimination of cyclic phase ambiguities. Simulations are presented to show the performance of the algorithm.

Study of ultra-wideband radar signals-generated technology using two-channel signal generator

Wan Yonglun 1, Lu Youxin 2, Si Qiang 2, Wang Xuegang 2 & Cao Guangping 1
2007, 18(4):  710-715. 
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Synthesis of ultra-wideband (UWB) linear frequency modulation radar signals is a very important technology for microwave imaging, target identi cation and detection of low radar-cross-section (RCS) targets. A new method of UWB radar signals generation with two-channel signal generator is presented. The realization structure is given; the principle and errors of signal synthesis are analyzed. At the same time, an automatic adjustment measure of signal phase is proposed because of phase discontinuity of waveform in this method. The simulation experiment and analysis results indicate that radar signals with large instantaneous bandwidth can be generated by means of this method on the condition that the high-speed digital devices are limited.

Simpli ed iterative algorithm for OFDM phase noise mitigation
Yang Jianhua, Zhao Danfeng, Yue Li & Zhao Chunhui
2007, 18(4):  716-720. 
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OFDM has been widely adopted in several communication systems. However, OFDM systems are very sensitive to the phase noise, which causes the CPE (common phase error) and ICI (inter-carrier interference), and thus degrades the system performance signi cantly. Based on the IEEE 802.11a standard, a simpli ed iterative phase noise mitigation algorithm is proposed. The proposed algorithm has very low complexity, and requires no additional pilot information. The simulation result shows that good BER performance can be achieved through several few times of iteration.

Design of continuous long slot leaky-wave antenna for millimeter wave application
Lv Shanwei, Zhang Yan, Liu Juan & Zhang Jiangling
2007, 18(4):  721-725. 
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A simple and efficient design scheme of the continuous long slot leaky-wave antenna is developed. The key steps involved in the scheme are summarized. First, the cut-off frequencies of slot waveguides with different slot offsets are obtained by 3D finite-diffierence time-domain (FDTD) method. Second, the attenuation function αra is estimated by the aperture distribution, and the attenuation function αrs is determined by the slot radiation. Finally, the attenuation function αra is combined with the attenuation function αrs by the coefficient K. And an example in Ka band is presented. Moreover, the return loss of the E-plane Tee-junction (ET) and the radiation pattern of leaky-wave antenna are simulated. The scheme is verified by comparing with the experimental result.

New hybridization of PO, SBR, and MoM for scattering by large complex conducting objects
Dong Chunzhu, Geng Fangzhi, Yin Hongcheng & Wang Chao
2007, 18(4):  726-730. 
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As a marked extension of the traditional MoM-PO (method of moment-physical optics) hybrid method, a new hybridization of PO, SBR, and MoM (MoM-SBR/PO) is presented to calculate the multi-reection contribution in the PO region efficiently by introducing the method of SBR based on RDN notion, which avoids the time-consuming iterative procedure and the choice of proper Green's function. As compared with the traditional MoM-PO hybrid method, the calculation eciency of the proposed method is greatly improved, and its validity is verified by numerical results.

Utility function based fair data scheduling algorithm for OFDM wireless network
Guo Kunqi, Sun Lixin & Jia Shilou
2007, 18(4):  731-738. 
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A system model is formulated as the maximization of a total utility function to achieve fair downlink data scheduling in multiuser orthogonal frequency division multiplexing (OFDM) wireless networks. A dynamic subcarrier allocation algorithm (DSAA) is proposed, to optimize the system model. The subcarrier allocation decision is made by the proposed DSAA according to the maximum value of total utility function with respect to the queue mean waiting time. Simulation results demonstrate that compared to the conventional algorithms, the proposed algorithm has better delay performance and can provide fairness under different loads by using different utility functions.

Estimation of detection threshold in multiple ship target situations with HF ground wave radar
Li Hongbo, Shen Yiying & Liu Yongtan
2007, 18(4):  739-744. 
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A credible method of calculating the detection threshold is presented for the multiple target situations, which appear frequently in the lower Doppler velocity region during the surveillance of sea with HF ground wave radar. This method defines a whole-peak-outlier elimination (WPOE) criterion, which is based on in-peak-samples correlation of each target echo spectra, to trim o the target signals and abnormal disturbances with great amplitude from the complex spectra. Therefore, cleaned background noise samples are obtained to improve the accuracy and reliability of noise level estimation. When the background noise is nonhomogeneous, the detection samples are limited and often occupied heavily with outliers. In this case, the problem that the detection threshold is overvalued can be solved. In applications on experimental data, it is verified that this method can reduce the miss alarm rate of signal detection effectively in multiple target situations as well as make the adaptability of the detector better.

Scale transform algorithm used in FMCW SAR data processing
Jiang Zhihong, Kan Huangfu & Wan Jianwei
2007, 18(4):  745-750. 
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The frequency-modulated continuous-wave (FMCW) synthetic aperture radar (SAR) is a light-weight, cost-effective, high-resolution imaging radar, which is suitable for a small flight platform. The signal model is derived for FMCW SAR used in unmanned aerial vehicles (UAV) reconnaissance and remote sensing. An appropriate algorithm is proposed. The algorithm performs the range cell migration correction (RCMC) for continuous non-chirped raw data using the energy invariance of the scaling of a signal in the scale domain. The azimuth processing is based on step transform without geometric resampling operation. The complete derivation of the algorithm is presented. The algorithm performance is shown by simulation results.

Quantified simulation research on harmonious factors in the leadership teams of aerospace enterprise group
Yin Xingliang, Hu Yunquan, Yang Fuping, Zhao Hanping & Tang Ning
2007, 18(4):  751-757. 
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A brief account of basic connotation and evaluation indexes system of harmonious leadership teams is given. On this basis, a simulation model is built by using the ARENA simulation software and the quantified simulation is carried out for the factors of harmonization of aerospace enterprise leadership teams. Moreover, by taking the characteristics of aerospace enterprise leadership teams into consideration, the comparison of harmonization quantified results of several typical leadership teams, especially on the comparative analysis of influencing degrees of moral characters and capabilities on the leadership teams overall harmonization is emphatically discussed. Finally, a conclusion is drawn.

Decentralized and overall condition monitoring system for large-scale mobile and complex equipment
Cao Jianjun, Zhang Peilin, Ren Guoquan & Fu Jianping
2007, 18(4):  758-763. 
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It is an urgent project to realize online and overall condition monitoring and timely fault diagnosis for large-scale mobile and complex equipment. Moreover, most of the existing large-scale complex equipment has quite insufficient accessibility of examination, although it still has quite a long service life. The decentralized and overall condition monitoring, as a new concept, is proposed from the point of view of the whole system. A set of complex equipment is divided into several parts in terms of concrete equipment. Every part is processed via one detecting unit, and the main detecting unit is connected with other units. The management work and communications with the remote monitoring center have been taken on by it. Consequently, the difficulty of realizing a condition monitoring system and the complexity of processing information is reduced greatly. Furthermore, excellent maintainability of the condition monitoring system is obtained because of the modularization design. Through an application example, the design and realization of the decentralized and overall condition monitoring system is introduced specifically. Some advanced technologies, such as, micro control unit (MCU), advanced RISC machines (ARM), and control area network (CAN), have been adopted in the system. The system's applicability for the existing large-scale mobile and complex equipment is tested.

F-generation law and recognition of system law
Shi Kaiquan & Yao Bingxue
2007, 18(4):  764-768. 
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If a system is not disturbed (or invaded) by some law, there is no doubt that each system will move according to the expected law and keep stable. Although such a fact often appears, some unknown law breaks into the system and leads it into turbulence. Using function one direction S-rough sets, this article gives the concept of the F-generation law in the system, the generation model of the F-generation law and the recognition method of the system law. Function one direction singular rough sets is a new theory and method in recognizing the disturbance law existing in the system and recognizing the system law.

SVR mathematical model and methods for sale prediction
Yi Yang, Rong Fuli, Chang Huiyou & Xiao Zhijiao
2007, 18(4):  769-773. 
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Sale prediction plays a significant role in business management. By using support vector machine Regression (ε-SVR), a method using to predict sale is illustrated. It takes historical data and current context data as inputs and presents results, i.e. sale tendency in the future and the forecasting sales, according to the user's specification of accuracy and time cycles. Some practical data experiments and the comparative tests with other algorithms show the advantages of the proposed approach in computation time and correctness.

Novel combinatorial algorithm for the problems of fuzzy grey multi-attribute group decision making
Rao Congjun, Xiao Xinping & Peng Jin
2007, 18(4):  774-780. 
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To study the fuzzy and grey information in the problems of multi-attribute group decision making, the basic concepts of both fuzzy grey numbers and grey interval numbers are given firstly, then a new model of fuzzy grey multi-attribute group decision making based on the theories of fuzzy mathematics and grey system is presented. Furthermore, the grey interval relative degree and deviation degree is defined, and both the optimistic algorithm of the grey interval relational degree and the algorithm of deviation degree minimization for solving this new model are also given. Finally, a decision making example to demonstrate the feasibility and rationality of this new method is given, and the results by using these two algorithms are uniform.

Analysis method on shoot precision of weapon in small-sample case
Jiang Jun, Song Baowei & Liang Qingwei
2007, 18(4):  781-784. 
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Because of limits of cost, in general, the test data of weapons are shortness. It is always an important topic that to gain scientific results of weapon performance analyses in small-sample case. Based on the analysis of distribution function characteristics and grey mathematics, a weighting grey method in small-sample case is presented. According to the analysis of test data of a weapon, it is proved that the method is a good method to deal with data in the small-sample case and has a high value in the analysis of weapon performance.

Multi-agent cooperative intrusion response in mobile adhoc networks
Yi Ping, Zou Futai, Jiang Xinghao & Li Jianhua
2007, 18(4):  785-794. 
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The nature of adhoc networks makes them vulnerable to security attacks. Many security technologies such as intrusion prevention and intrusion detection are passive in response to intrusions in that their countermeasures are only to protect the networks, and there is no automated network-wide counteraction against detected intrusions. the architecture of cooperation intrusion response based multi-agent is propose. The architecture is composed of mobile agents. Monitor agent resides on every node and monitors its neighbor nodes. Decision agent collects information from monitor nodes and detects an intrusion by security policies. When an intruder is found in the architecture, the block agents will get to the neighbor nodes of the intruder and form the mobile firewall to isolate the intruder. In the end, we evaluate it by simulation.

High performance scalable image coding
Gan Tao, He Yanmin & Zhu Weile
2007, 18(4):  795-800. 
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A high performance scalable image coding algorithm is proposed. The salient features of this algorithm are the ways to form and locate the significant clusters. Thanks to the list structure, the new coding algorithm achieves fine fractional bit-plane coding with negligible additional complexity. Experiments show that it performs comparably or better than the state-of-the-art coders. Furthermore, the exible codec supports both quality and resolution scalability, which is very attractive in many network applications.

Fusion of multiagent preference orderings with information on agent's importance being incomplete certain
Wang Jianqiang
2007, 18(4):  801-805. 
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The problem of fusing multiagent preference orderings, with information on agent's importance being incomplete certain with respect to a set of possible courses of action, is described. The approach is developed for dealing with the fusion problem described in the following sections and requires that each agent provides a preference ordering over the di erent alternatives completely independent of the other agents, and the information on agent's importance is incomplete certain. In this approach, the ternary comparison matrix of the alternatives is constructed, the eigenvector associated with the maximum eigenvalue of the ternary comparison matrix is attained so as to normalize priority vector of the alternatives. The interval number of the alternatives is then obtained by solving two sorts of linear programming problems. By comparing the interval numbers of the alternatives, the ranking of alternatives can be generated. Finally, some examples are given to show the feasibility and effectiveness of the method.

Nonlinear approximation of image based on monoscale orthonormal ridgelets frame
Lu Chengwu, Song Yimei, Song Guoxiang
2007, 18(4):  806-810. 
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A new tight frame called as monoscale orthonormal ridgelet frame (MORF) is proposed. The localization principle and the orthonormal ridgelet constructed by Donoho are applied to construct the MORF, which are used to evaluate the order of nonlinear approximation for image with edge. Because the new tight frame not only has directionality but also bears orthonormality. It overcomes redundancy of Candes's monoscale ridgelets and provides many excellent properties in practical application. Theoretical analysis and experiments demonstrate that the new frame has remarkable potential for image compression, image reconstruction, and image denoising with the simple refinement for MORF.

Broadcast group-oriented encryption secure against chosen ciphertext attack
Ma Chunbo, Ao Jun & Li Jianhua
2007, 18(4):  811-817. 
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A novel broadcast encryption scheme for group communication scenarios in distributed networks is presented. In the scheme, anyone is allowed to encrypt a message and distribute it to a designated group. Each member in the designated group has the ability to independently decrypt a ciphertext. In contrast to traditional broadcast encryption, all the valid receivers in the proposed scheme compose the designated group. To take advantage of this property, a tab for the group is set and the matching private key for each member is generated. In addition, before decrypting a ciphertext, anyone in the scheme can verify the ciphertext, to ensure that the ciphertext is correct. This property is very important for large-scale group communication, as the gateway can filter incorrect ciphertext and alleviate the receiver's workload. Finally, a proof in the random oracle model is given, to show that the proposed scheme is secure against the adaptively chosen ciphertext attack.

Multi-path based secure communication in wireless mesh networks
Ding Xuyang, Fan Mingyu, Lu Xiaojun, Zhu Dayong & Wang Jiahao
2007, 18(4):  818-824. 
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Communication security is a critical aspect of QoS provisioning in wireless mesh network (WMN). Because of the inherent characteristics of WMN, conventional security mechanisms cannot be applied. In order to guarantee the communication security, a novel communication security mechanism is proposed. The mechanism uses a communication encryption scheme to encrypt data packets and employs a risk avoidance scheme to avoid the malicious nodes during communications. Simulation results indicate that the mechanism is able to provide secure communication effectively and reduce the damage of attacks through multiple paths.

Digital signature systems based on smart card and fingerprint feature
You Lin, Xu Maozhi, Zheng Zhiming
2007, 18(4):  825-834. 
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Two signature systems based on smart cards and fingerprint features are proposed. In one signature system, the cryptographic key is stored in the smart card and is only accessible when the signer's extracted fingerprint features match his stored template. To resist being tampered on public channel, the user's message and the signed message are encrypted by the signer's public key and the user's public key, respectively. In the other signature system, the keys are generated by combining the signer's fingerprint features, check bits, and a rememberable key, and there are no matching process and keys stored on the smart card. Additionally, there is generally more than one public key in this system, that is, there exist some pseudo public keys except a real one.

Distributed sampling measurement method of network traffic in high-speed IPv6 networks
Pan Qiao, Pei Changxing
2007, 18(4):  835-840. 
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With the advent of large-scale and high-speed IPv6 network technology, an effective multi-point traffic sampling is becoming a necessity. A distributed multi-point traffic sampling method that provides an accurate and efficient solution to measure IPv6 traffic is proposed. The proposed method is to sample IPv6 traffic based on the analysis of bit randomness of each byte in the packet header. It offers a way to consistently select the same subset of packets at each measurement point, which satisfies the requirement of the distributed multi-point measurement. Finally, using real IPv6 traffic traces, the conclusion that the sampled traffic data have a good uniformity that satisfies the requirement of sampling randomness and can correctly reflect the packet size distribution of full packet trace is proved.

Improvement of precision for pendulous integrating gyro accelero-meter via adaptive internal model control
Xu Fengxia, Xia Gang, Zeng Ming, Sun Baoku & Zhao Xuezeng
2007, 18(4):  841-845. 
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An adaptive internal mode control is proposed to eliminate e®ectively periodic disturbance with un-certain frequency caused by input error angle of PIGA (Pendulous Integrating Gyro Accelerometer). An adaptive algorithm with periodic disturbance frequency identi¯cation on line is applied and the internal model controller parameters are adjusted to eliminate disturbance. Then the convergence of this algorithm and the stability of the system are proved by the averaging method. Simulation results verify the proposed scheme can eliminate periodic disturbance and improve the test precision for PIGA effectively.

Guaranteed cost control with constructing switching law of uncertain discrete-time switched systems
Zhang Ying & Duan Guangren
2007, 18(4):  846-851. 
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A guaranteed cost control problem for a class of linear discrete-time switched systems with norm-bounded uncertainties is considered in this article. The purpose is to construct a switching rule and design a state feedback control law, such that, the closed-loop system is asymptotically stable and the closed-loop cost function value is not more than a specified upper bound for all admissible uncertainties under the constructed switching rule. A sufficient condition for the existence of guaranteed cost controllers and switching rules is derived based on the Lyapunov theory together with the linear matrix inequality (LMI) approach. Furthermore, a convex optimization problem with LMI constraints is formulated to select the suboptimal guaranteed cost controller. A numerical example demonstrates the validity of the proposed design approach.

Design of performance robustness for uncertain nonlinear time-delay systems via neural network
Luan Xiaoli & Liu Fei
2007, 18(4):  852-857. 
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Performance robustness problems via the state feedback controller are investigated for a class of uncertain nonlinear systems with time-delay in both state and control, in which the neural networks are used to model the nonlinearities. By using an appropriate uncertainty description and the linear difference inclusion technique, su±cient conditions for existence of such controller are derived based on the linear matrix inequalities (LMIs). Using solutions of LMIs, a state feedback control law is proposed to stabilize the perturbed system and guarantee an upper bound of system performance, which is applicable to arbitrary time-delays.

Delay-independent robust guaranteed-cost control for uncertain linear neutral systems
Li Hongfei & Zhou Jun
2007, 18(4):  858-864. 
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This article concerns the delay-independent guaranteed-cost control problem via memoryless state feedback for a class of neutral-type systems with structural uncertainty and a given quadratic cost function. New delay-independent conditions for the existence of the guaranteed-cost controller are presented in the term of LMIs. An algorithm involving optimization is proposed to design a controller achieving an optimal guaranteed-cost, such that, the system can be stabilized for all admissible uncertainties. A numerical example is provided to illustrate the feasibility of the proposed method.

Adaptive variable structure control for large-scale time-delayed systems with unknown nonlinear dead-zone
Shen Qikun & Zhang Tianping
2007, 18(4):  865-870. 
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The problem of adaptive fuzzy control for a class of large-scale, time-delayed systems with unknown nonlinear dead-zone is discussed here. Based on the principle of variable structure control, a design scheme of adaptive, decentralized, variable structure control is proposed. The approach removes the conditions that the dead-zone slopes and boundaries are equal and symmetric, respectively. In addition, it does not require that the assumptions that all parameters of the nonlinear dead-zone model and the lumped uncertainty are known constants. The adaptive compensation terms of the approximation errors are adopted to minimize the in influence of modeling errors and parameter estimation errors. By theoretical analysis, the closed-loop control system is proved to be semi-globally uniformly ultimately bounded, with tracking errors converging to zero. Simulation results demonstrate the effectiveness of the approach.

Robust decentralized H∞ control of multi-channel systemswith norm-bounded parametric uncertainties
Chen Ning & Gui Weihua
2007, 18(4):  871-878. 
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A robust decentralized H∞ control problem for uncertain multi-channel systems is considered. The uncertainties are assumed to be time-invariant, norm-bounded, and exist in both the system and control input matrices. The dynamic output feedback is mainly dealt with. A necessary and sufficient condition for the uncertain multi-channel system to be stabilized robustly with a speci ed disturbance attenuation level is derived based on the bounded real lemma, which is reduced to a feasibility problem of a nonlinear matrix inequality (NMI). A two-stage homotopy method is used to solve the NMI iteratively. First, a decentralized controller for the nominal system with no uncertainty is computed by imposing structural constraints on the coefficient matrices of the controller gradually. Then the decentralized controller is modified, again gradually, to cope with the uncertainties. On each stage, a variable is fixed alternately at the iterations to reduce the NMI to a linear matrix inequality (LMI). A given example shows the efficiency of this method.

Delay-dependent robust passivity control for uncertain time-delay systems
Li Guifang, Li Huiying & Yang Chengwu
2007, 18(4):  879-884. 
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The robust passivity control problem is addressed for a class of uncertain delayed systems with time-varying delay. The parameter uncertainties are norm-bounded. First, the delay-dependent stability sufficient condition is obtained for the nominal system, and then, based-on the former, the delay-dependent robust passivity criteria is provided and the corresponding controller is designed in terms of linear matrix inequalities. Finally, a numerical example is given to demonstrate the validity of the proposed approach.

Guaranteed control performance robust LQG regulator for discrete-time Markovian jump systems with uncertain noise
Zhu Jin, Xi Hongsheng, Xiao Xiaobo & Ji Haibo
2007, 18(4):  885-891. 
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Robust LQG problems of discrete-time Markovian jump systems with uncertain noises are investigated. The problem addressed is the construction of perturbation upper bounds on the uncertain noise covariances so as to guarantee that the deviation of the control performance remains within the precision prescribed in actual problems. Furthermore, this regulator is capable of minimizing the worst performance in an uncertain case. A numerical example is exploited to show the validity of the method.