查看更多>>摘要：This article aims to identify the topology and system parameter of fractional-order complex dynamical networks. The unknown topology and system parameter of the drive network are successfully identified under several controllers and update strategies. Moreover, we propose a lemma as the necessary condition to ensure successful identification. Two numerical simulations conclude that the high heterogeneity between the nodes of the drive network facilitates identification. (C) 2021 Published by Elsevier Inc.
查看更多>>摘要：This article includes an analytical investigation of the surface waves propagation in a uniform liquid layer overlying a homogeneous anisotropic (monoclinic) half-space. The waves are allowed to propagate through the interface, i.e., between the layer and the medium. Basic arithmetic procedures are employed to derive the dispersion equation for surface waves propagation. A comprising study is accomplished through numerical estimation to study the behavior of surface waves. Further analysis of surface waves in the absence of a liquid layer manifests that the phase velocity equation loses its dispersity like waves propagation in an isotropic medium. Some particular cases are extracted from the dispersion equation by taking correspondence with the results. Graphical software has been emerged to establish a criterion for the usefulness of several parameters discussed. (c) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：A new explicit stochastic scheme of order 1 is proposed for solving commutative stochastic differential equations (SDEs) with non-globally Lipschitz continuous coefficients. The proposed method is a semi-tamed version of Milstein scheme to solve SDEs with the drift coefficient consisting of non-Lipschitz continuous term and globally Lipschitz continuous term. It is easily implementable and achieves higher strong convergence order. A stability criterion for this method is derived, which shows that the stability condition of the numerical methods and that of the solved equations keep uniform. Compared with some widely used numerical schemes, the proposed method has better performance in inheriting the mean square stability of the exact solution of SDEs. Numerical experiments are given to illustrate the obtained convergence and stability properties. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：This paper presents a adaptive dynamic programming-based fault detection and isolation (FDI) scheme to detect and isolate faults in an aircraft jet engine. To this end, the weights in Actor-Critic neural networks are first tuned to learn the input-output map of the jet engine considering its multiple working modes. The convergences of the trainings in Critic-Actor neural networks are strictly proved without knowing the drift dynamics and the input dynamics in the presence of unknown nonlinearities and approximation errors. Using the residuals that are generated by measuring the difference of each network output and the measured engine output, various criteria are established for accomplishing the fault diagnosis task, that addresses the problem of fault detection and isolation of the system components. A number of simulation studies are carried out for combustion chamber of a single-spool jet engine to demonstrate and illustrate the advantages, capabilities, and performance of our proposed fault diagnosis scheme. (c) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：The aim of the present paper is to provide new criteria for the asymptotic behaviors of dynamical systems, approaching simultaneously four directions: nonuniform, uniform stability and respectively nonuniform, uniform expansiveness, treating both discrete and continuous-time case and using computational type methods. In order to characterize the asymptotic properties of discrete variational systems, we consider two classes of weighted l(infinity)-spaces and we define two types of nonuniform input-output properties, by employing spaces from these classes in the admissible pair. Our study continues the line initiated in Dragi.cevi ' c, Sasu and Sasu [J. Differential Equations 268 (2020), 4786-4829] and [J. Dynam. Differential Equations, doi.org/10.1007/s10884-020-09918-4], giving a completely new perspective regarding the connections between admissibility techniques for stability and expansiveness. We obtain necessary and sufficient conditions for nonuniform, uniform exponential stability and also for nonuniform, uniform exponential expansiveness, providing a unified approach and emphasizing the key differences when passing from nonuniform to uniform behavior. Next, we present two categories of applications of the discrete-time results. First, we deduce criteria for stability and expansiveness in terms of input-output type properties along period orbits. After that, we obtain characterizations for uniform exponential stability and uniform exponential expansiveness of skew-product semiflows in terms of the solvability of an associated integral control system between well-chosen weighted spaces of continuous functions, pointing out new computational methods of recovering the continuous information from the discrete-time behavior in the framework of nonuniform input-output techniques. Our results are applicable to general classes of variational systems. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：A key to the analysis and design of a dynamic system is to establish a suitable mathematical model of the system. This paper investigates the parameter optimization problem of a class of radial basis function-based multivariate hybrid models. Taking into account the high dimensions of the models and different forms of the parameters, the original identification model is separated into several regressive sub-identification models according to the characteristics of model outputs. Some auxiliary models are constructed to solve the unmeasurable noise terms in the information matrices. For the purpose of eliminating the redundant computation and to deal with the associate terms caused by the model decomposition, inspired by the coupling concept, a partially-coupled nonlinear parameter optimization algorithm is proposed for the multivariate hybrid models. Through the computational efficiency analysis and numerical simulation verification, it is shown that the proposed algorithm has low computational complexity and high parameter estimation accuracy. (c) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：This paper presents an fault detection (FD) method for a class of uncertain nonlinear systems with unmatched nonlinear fault functions and disturbances. A recursive FD observer is designed with predetermined and small output estimation error. The nonlinear observer gain function is achieved by introducing predetermined output estimation accuracy-dependent nonnegative functions. Combining Lyapunov functions, it is shown that the absolute value of the residual signal is equal or lesser than tight threshold before fault occurrence. The FD scheme is proposed following fault detectability analysis, simulation example indicates the validity of the proposed method. (c) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：This paper investigates the observer-based quantized output feedback control for a kind of nonlinear discrete-time systems. The system studied in this paper is denoted by a Takagi-Sugeno (T-S) fuzzy model. Under digital communication channels, all transmitted signals between the system and the actuator (including the controller and the observer) will be quantized by the dynamic quantizers in the closed-loop system. Taking into consideration the design of the controller, observer, and dynamic parameters of quantizers, an effective matrix inequality decoupling method is presented to handle the problem. One is shown that the proposed design conditions of the controller, observer, dynamic parameters of quantizers are summarized in a matrix inequality, which can be synthesized synchronously. The resulting design ensures that the quantized closed-loop system can meet the prescribed H-infinity performance. Finally, the availability and the feasibility of the presented design method are demonstrated by a mechanical motion system. (C) 2021 Published by Elsevier Inc.
查看更多>>摘要：Computing a defective eigenvalue is an ill-posed problem if components of the matrix are approximate data. Using the definition of multiplicity support of a defective eigenvalue introduced by Zeng, we consider the verification about the sensitivity and computation of a defective eigenvalue of a real matrix. We discuss how to construct a slightly perturbed interval matrix which is guaranteed to possess a real matrix with computed defective eigenvalue of computed multiplicity support. Furthermore, we also obtain an interval matrix which is guaranteed to possess a real matrix. The columns of the real matrix span the corresponding eigenvector space. (c) 2021 Elsevier Inc. All rights reserved.
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