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New lower solution bounds of the continuous algebraic Riccati matrix equation

LINEAR ALGEBRA AND ITS APPLICATIONS 2007年第2-3期427卷 242-255页

作者： Davies, Richard Shi, Peng Wiltshire, Ron Univ Glamorgan Fac Adv Technol Pontypridd CF37 1DL M Glam Wales

In optimal and robust control problems, the so-called continuous algebraic Riccati equation (CARE) plays an important part. By utilizing some matrix inequalities and linear algebraic techniques, new lower matrix bounds for the solution of the CARE are derived. Following the derived bounds, iterative algorithms are then developed to obtain sharper solution estimates. In comparison to existing results, the obtained bounds are less restrictive. Finally, we give numerical examples to demonstrate the effectiveness of our results. (C) 2007 Elsevier Inc. All rights reserved.

关键词： matrix bound continuous algebraic Riccati equation iterative algorithm

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Multistage channel estimation and data detection for multi-antenna CDMA systems with single spreading code per user

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IEICE TRANSACTIONS ON COMMUNICATIONS 2007年第12期E90B卷 3523-3529页

作者： Tseng, Shu-Ming Yu, Hung-Chieh Natl Taipei Inst Technol Dept Elect Engn Taipei Taiwan

A training-based vector channel estimation method has been proposed for single-user code-division multiple access (CDMA) systems in fast-varying correlated multipath fading channels. In this paper, we extend it in an iterative way to multiuser multiple-input multiple-output (MIMO) CDMA systems where both the transmitter and receiver have multiple antennas. In the training period, we propose to add the minimum mean square error (MMSE) front end before channel estimation to suppress multiuser interference (MUI) from substreams with difference spreading codes, so then we can get good initial vector channel estimation for each user. In the data transmission period, we proposed to add MMSE/parallel interference cancellation (PIC) front end to suppress MUI, interference suppression, and vector channel estimation in an iterative way. The perfect channel estimation is assumed in Liu et al., and the inter-play between channel estimation and multiuser detection is not discussed either. On the contrary, the novelty of the proposed method is that we add MMSE/PIC front end (in addition to matched filter) before channel estimation and we repeatedly switch between MMSE/PIC front end and channel estimation.

关键词： iterative algorithm inter-antenna interference

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Automatic modulation classification of composite FM/PM speech signals in sensor arrays over flat fading channel

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IET COMMUNICATIONS 2007年第2期1卷 157-164页

作者： El-Mahdy, A. E. Mil Tech Coll Dept Elect Engn Cairo Egypt

A method for automatic classification of composite FM/PM speech signals is proposed here. The method classifies a number of intercepted signals into FM or PM, provided that each signal is either speech FM or PM. The signals are transmitted through flat fading channels and contaminated with white Gaussian noise. A linear array consisting of several sensors is constructed to intercept these signal. The minimum description length criterion is used to estimate the number of intercepted signals. The maximum likelihood approach is used to estimate the direction of arrival of each signal, the fading channel, coefficients and the noise variance. The classification procedure is based on estimation of the phase waveform which contains the speech signal. An iterative algorithm is derived to perform this estimate for each signal and then the resulting estimate is used to develop a method to determine, for each signal, if it is FM or PM. The method is based on evaluating the power spectral density of the instantaneous frequency of the intercepted signal which is distinctive in speech FM and PM signals. Computer simulations are performed to validate the theoretical developments.

关键词： iterative methods maximum likelihood estimation speech processing fading channels direction of arrival estimation sensor arrays frequency modulation composite FM-PM speech signal phase modulation direction-of-arrival estimation signal classification maximum likelihood approach Gaussian noise flat fading channel array signal processing power spectral density iterative algorithm automatic modulation classification

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A novel algorithm for two-dimensional frequency estimation

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SIGNAL PROCESSING 2007年第1期87卷 1-12页

作者： Zhou, Yi Feng, Da-zheng Liu, Jain-qiang Xidian Univ Key Lab Radar Signal Proc Xian 710071 Peoples R China

This paper addresses the two-dimensional (2-D) frequency estimation embedded in additive Gaussian noise. By use of the biorthogonatity of matrices and rotational invariance property, we construct an interesting cost function and propose a novel iterative algorithm for 2-D frequency estimation, which obtains one column of the Vandermonde matrix containing 1-D frequencies and the corresponding column of the Vander-monde matrix containing the other 1-D frequencies at each stage. Therefore, the proposed algorithm can pair the 2-D frequencies automatically. The convergence of the proposed iterative algorithm is also proven. Moreover, all the columns of the frequency matrices can be obtained by systematically multistage decomposition and multistage reconstruction. Simulation results are provided to show the good performance of the proposed algorithm. (c) 2006 Elsevier B.V. All rights reserved.

关键词： two-dimensional frequency estimation rotational invariance biorthogonality iterative algorithm cyclic minimization

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Cross-layer distributed approach for optimal rate allocation for homogeneous wireless multicast

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IET COMMUNICATIONS 2007年第5期1卷 838-845页

作者： Mohamed, A. Alnuweiri, H. Univ British Columbia Dept Elect & Comp Engn Vancouver BC V6T 1Z4 Canada

Multicast-based data communication is an efficient communication scheme especially in multihop ad hoc networks where the MAC layer is based on one-hop broadcast from one source to multiple receivers. The problem of resource allocation for a set of homogeneous multicast sessions over multihop wireless network is addressed. An iterative algorithm is proposed that achieves the optimal rates for a set of multicast sessions such that the aggregate utility for all sessions is maximised. The authors demonstrate analytically and through simulations that the algorithm achieves optimal resource utilisation while guaranteeing fairness among multicast sessions. The algorithm in network environments with asynchronous distributed computations has been further analysed. Two implementations for the algorithm based on different network settings are presented and show that the algorithm not only converges to the optimal rates in all network settings but it also tracks network changing conditions, including mobility and dynamic channel capacity.

关键词： iterative methods multicast protocols resource allocation access protocols cross-layer distributed approach optimisation homogeneous wireless multicast sessions ad hoc networks optimal rate allocation resource optimisation multicast-based data communication distributed algorithms resource allocation problem MAC layer iterative algorithm multihop ad hoc networks

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iterative methods for solving variational inclusions in Banach spaces

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2007年第1期203卷 80-86页

作者： He, Xin-Feng Lou, Jian He, Zhen Hebei Univ Coll Math & Comp Baoding 071002 Peoples R China Hebei Univ Ctr Comp Baoding 071002 Peoples R China

In this paper, we consider a system of nonlinear variational inclusions involving H-accretive operators studied by Huang and Fang in q-uniformly smooth Banach spaces. Using resolvent operator technique, we suggest an iterative algorithm for finding all approximate solution to the system of variational inclusions. Further, we discuss convergence criteria for the approximate solution of the system of variational inclusions. The theorems presented in this paper improve and unify many known results of variational inclusions. (c) 2006 Elsevier B.V. All rights reserved.

关键词： q-uniformly smooth space H-accretive operator mapping resolvent operator technique a system of nonlinear variational inclusions iterative algorithm

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Experimental and numerical investigation of structural damage detection using changes in natural frequencies

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JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME 2007年第6期129卷 686-700页

作者： Xu, G. Y. Zhu, W. D. Emory, B. H. Univ Maryland Baltimore Cty Dept Mech Engn Baltimore MD 21250 USA

A robust iterative algorithm is used to identify the locations and extent of damage in beams using only the changes in their first several natural frequencies. The algorithm, which combines a first-order multiple-parameter perturbation method and the generalized inverse method, is tested extensively through experimental and numerical means on cantilever beams with different damage scenarios. If the damage is located at a position within 0-35% or 50-95% of the length of the beam from the cantilevered end, while the resulting system equations are severely underdetermined, the minimum norm solution from the generalized inverse method can lead to a solution that closely represents the desired solution at the end of iterations when the stiffness parameters of the undamaged structure are used as the initial stiffness parameters. If the damage is located at a position within 35-50% of the length of the beam from the cantilevered end, the resulting solution by using the stiffness parameters of the undamaged structure as the initial stiffness parameters deviates significantly from the desired solution. In this case, a new method is developed to enrich the measurement information by modifying the structure in a controlled manner and using the first several measured natural frequencies of the modified structure. A new method using singular value decomposition is also developed to handle the ill-conditioned system equations that occur in the experimental investigation by using the measured natural frequencies of the modified structure.

关键词： structural damage detection natural frequency changes perturbation method generalized inverse method iterative algorithm underdetermined system equations cantilever beams enrichment of measurement information ill-conditioned system equations

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A New System of Variational Inclusions with(H,η)-accretive Operators in Banach Spaces

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Chinese Quarterly Journal of Mathematics 2008年第4期000卷

作者： LIU Ying CHEN Yong-li HE Zhen College of Mathematics and Computer Hebei UniversityBaoding 071002China College of Technology North China Electric Power UniversityBaoding 071051China

In this paper,we first introduce a new class of generalized accretive operators named(H,η)-accretive in Banach *** studying the properties of(H,η)-accretive,we extend the concept of resolvent operators associated with m-accretive operators to the new(H,η)-accretive *** terms of the new resolvent operator technique,we prove the existence and uniqueness of solutions for this new system of variational *** also construct a new algorithm for approximating the solution of this system and discuss the convergence of the sequence of iterates generated by the algorithm.

关键词： q-uniformly smooth Banach space (H η)-accretive operator resolvent operatortechnique system of variational inclusion iterative algorithm

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iterative contextual recurrent classification of chromosomes

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NEURAL PROCESSING LETTERS 2007年第3期26卷 159-175页

作者： Martinez, Cesar Juan, Alfons Casacuberta, Francisco Univ Nacl Entre Rios Fac Ingn Parana Entre Rios Argentina Univ Nacl Litoral Fac Ingn & Ciencias Hidricas Santa Fe Argentina Univ Politecn Valencia DSIC ITI E-46071 Valencia Spain

Recurrent connectionist models provide a method to represent dynamic patterns in a neural network. In this work we present a method for chromosome classification based on an almost unexplored neural network technique for this task. A partially recurrent connectionist model, the Elman network, is managed to capture the dark and light band patterns of the different classes. The proposed method is completed with the formulation of the ICC (iterative contextual classification) algorithm in order to restrict the classification to the cell context, and is applied to the neural network results. The Copenhagen data set was used in the experiments, where a cross-validation method was applied in order to obtain statistically representative results using the complete corpus. The entire system obtained very good results for this task, improving the performance of other neural network approaches.

关键词： chromosome classification recurrent neural networks Elman network context-dependent classification iterative algorithm

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On-line parameter estimator derived from modified matrix pseudoinverse

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APPLIED MATHEMATICS AND COMPUTATION 2007年第2期189卷 1139-1145页

作者： Gonzalez, Graciela Adriana Univ Buenos Aires Fac Ingn Dept Matemat RA-1063 Buenos Aires DF Argentina

A method based on the matrix pseudoinverse is considered for on-line parameter identification of discrete-time nonlinear systems. A recursive scheme was previously reported but assuming some restrictions on the input-output data. By resorting to the formulae developed for modified matrix pseudoinverse, an iterative algorithm is derived in this work. This algorithm applies to the general class of proposed systems while keeping well known desired properties for parameter identification. (c) 2006 Elsevier Inc. All rights reserved.

关键词： discrete-time nonlinear systems parameter identification least-squares problem iterative algorithm matrix pseudoinverse

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