Game theory‐based MIMO cognitive radio systems: Accuracy examination

The Letter proposes a precise mathematical expression for game theory‐based multiple‐input multiple‐output (MIMO) cognitive radio systems. The sum of information rates and the network utility are maximized, providing an accurate examination. Constraining the interference signals caused by the secondary transmitters on the primary receivers in the underlay scenario also needs to be addressed. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

An Imanishism‐based genetic algorithm for sampling various Pareto‐optimal solutions: An application to the multiobjective resource division problem

For sampling various solutions from the entire Pareto front of the multiobjective resource division problem, a new Genetic Algorithm (GA) based on an evolutionary theory advocated by Kinji Imanishi is proposed. First, two types of distance between two individuals, namely, structural and functional distances, are introduced and used to define four types of relation between them, namely, homogeneous, heterogeneous, homologous, and analogous species. Then, for keeping a variety of species within a population as far as possible, a new generation alternation model with variable population size is presented. In order to find Pareto‐optimal solutions effectively, a new genetic operation that combines conventional harmonic crossover with a local optimization algorithm is also proposed. Finally, the advantage of the Imanishism‐based GA is demonstrated through computational experiments conducted on two‐ and three‐objective problem instances. © 2002 Scripta Technica, Electr Eng Jpn, 139(2): 23–35, 2002; DOI 10.1002/eej.10010     

Stochastic H∞ control problem with state‐dependent noise for weakly coupled large‐scale systems

In this paper, stochastic H_∞ state feedback control with state‐dependent noise for weakly coupled large‐scale systems is discussed. After establishing the asymptotic structure of the stochastic algebraic Riccati equation (SARE), a new iterative algorithm that combines the Newton's method with the fixed‐point algorithm is derived for the first time. As a result, both the quadratic convergence and the reduced‐order computation in the same dimension of the subsystems are attained. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Adaptive B‐spline neural network‐based vector control for a grid side converter in wind turbine‐DFIG systems

This paper presents a novel control system design for the grid‐side converter of doubly fed induction generator wind power generation systems. The control method proposed in this work is a vector control based on adaptive B‐spline neural network by using a simple fixed‐gain stabilizing control topology. The adaptive control is designed both for inner current loops and an outer DC‐link voltage loop of the grid side converter control system. To guarantee the control stability, the weights updating rule for the B‐spline neural network is synthesized by utilizing Lyapunov's direct method. To verify the effectiveness of the proposed control system, extensive simulations are performed using MATLAB/Simulink. Based on the simulation results, it is concluded that the proposed controller has improved performance compared to an optimum proportional integral control system. It is also relatively robust against external disturbances and variations of the control parameters. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

On the terminal region of model predictive control for non‐linear systems with input/state constraints

This paper addresses the terminal region of model‐based predictive control (MPC) for non‐linear systems with control input and state constraints. Based on a stability condition of non‐linear MPC, a method to determine the terminal weighting term in the performance index and the terminal stabilizing control law to enlarge the terminal region and thus the domain of attraction of the non‐linear MPC is proposed. An LMI based optimization approach is developed to choose the terminal weighting item and fictitious terminal stabilizing control law so as to enlarge the terminal region of the non‐linear MPC method. The proposed method is illustrated by a numerical example and compares favourably with existing results. Copyright © 2003 John Wiley & Sons, Ltd.     

On the asymptotic property analysis for a class of adaptive control systems with σ‐modification

With the effect of σ‐modification in adaptive control systems, robustness is achieved at the potential expense of destroying some of the convergence properties. This paper proposes a qualitative analysis method for the situations where the σ‐modification may lead to perfect tracking and also, given the prior knowledge of system parameters, may allow proper modification of the adaptive algorithm. The applicability of the proposed analysis method is illustrated by two examples, where the system control gains that lead to global asymptotic convergence are given explicitly. Further, simulations are performed to verify the qualitative analysis results. Copyright © 2012 John Wiley & Sons, Ltd.     

A Green's function‐based method for the transient analysis of plane waves obliquely incident on lossy and dispersive planar layers

This paper presents a new methodology for the transient analysis of plane waves obliquely incident on a planar lossy and dispersive layer. The proposed model is based on the Sturm–Liouville problem associated with the propagation equations. Green's function is calculated in a series form and the open‐end impedance matrix is obtained as the sum of infinite rational functions. This form permits an easy identification of poles and residues. Furthermore, the knowledge of poles leads to the development of a model order reduction technique by selecting only the dominant poles of the system. The pole–residue representation is converted into a state‐space model that can be easily interfaced with ordinary differential equation solvers. The numerical results confirm the effectiveness of the proposed modeling technique. Copyright © 2008 John Wiley & Sons, Ltd.