检索结果-内蒙古大学图书馆

Optimizing a multigrid Runge-Kutta smoother for variable-coefficient convection-diffusion equations

linear algebra AND ITS applications 2017年 533卷 507-535页

作者： Bertaccini, Daniele DonateIli, Marco Durastante, Fabio Serra-Capizzano, Stefano Univ Roma Tor Vergata Dipartimento Matemat Viale Ric Sci 1 I-00133 Rome Italy Univ Insubria Dipartimento Sci & Alta Tecnol Via Valleggio 11 I-22100 Como Italy Uppsala Univ Dept Informat Technol Box 337 SE-75105 Uppsala Sweden

The theory of Generally Locally Toeplitz (or GLT for short) sequences of matrices is proposed in the analysis of a multigrid solver for the linear systems generated by finite volume/finite difference approximations of variable-coefficients linear convection diffusion equations in 1D, proposed by Birken in 2012, and extended here to 2D problems. The multigrid solver is used with a Runge-Kutta smoother. Optimal coefficients for the smoother are found by considering the unsteady linear advection equation and using optimization algorithms. In particular, in order to reduce the issues of having multiple local minima, the sequential quadratic programming (SQP) mixed with genetic and particle swarm optimization algorithms are proposed. numerical results show that our proposals are competitive with respect to other multigrid implementations. (C) 2017 Elsevier Inc. All rights reserved.

关键词： Multigrid Unsteady flows Finite volume methods Explicit Runge-Kutta methods linear advection equations GLT

来源：评论

学校读者我要写书评

暂无评论

International conference on Dynamical Systems: theory and applications, DSTA 2017

International Conference on Dynamical Systems: Theory and Ap...

引用

International conference on Dynamical Systems: theory and applications, DSTA 2017

ISBN: (纸本)9783319966007

The proceedings contain 44 papers. The special focus in this conference is on Dynamical Systems: theory and applications. The topics include: Accumulation of the Energy in Mechanical Resonance;application of Time-Frequency methods for Assessment of Gas Metal Arc Welding Condition;a 3-Link Model of a Human for Simulating a Fall in Forward Direction;reflectance and Transmittance of Cholesteric Liquid Crystal Sandwiched Between Polarizers;analysis of Nonlinear Dynamic Behavior of a Rotating Electrical Machine Rotor-Bearing System Using Optimal Auxiliary Functions Method;development of a Computational Based Reference Dynamics Model of a Flexible Link Manipulator;Optimization of Geometry of Cavitational Tunnel Using CFD Method;Application of numerical Simulations on 10GN2MFA Steel Multilayer Welding;application of Time-Frequency Analysis of Acoustic Signal to Detecting Flat Places on the Rolling Surface of a Tram Wheel;the Experimental Determination of Bearings Dynamic Coefficients in a Wide Range of Rotational Speeds, Taking into Account the Resonance and Hydrodynamic Instability;development of a Prototype Dynamic Weighing System for Single Bucket Excavator;design of Illumination and Lighting Visualization by Simulation methods;optimal Design of Multibody Systems Using the Adjoint Method;non-linear Modelling of Human Body Dynamic;dynamics of a Portable Module Handling System;dynamic Analysis of a Beam with Additional Auxiliary Mass Spatial Via Spectral Element Method;influence of Air Temperature on Dynamic Properties of Pipes Supplied with Pulsating Flow;model of Kinetic Energy Recuperation System for City Buses;signal Prediction in Bilateral Teleoperation with Force-Feedback;method of Direct Separation of Motions Applied to a Non-ideal Electromechanical Pendulum System.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Reduced modelling and fixed-order control of delay systems applied to a heat exchanger

引用

IET CONTROL theory AND applications 2017年第18期11卷 3341-3352页

作者： Michiels, Wim Hilhorst, Gijs Pipeleers, Goele Vyhlidal, Tomas Swevers, Jan Katholieke Univ Leuven Dept Comp Sci Celestijnenlaan 200A B-3001 Leuven Belgium Katholieke Univ Leuven Dept Mech Engn Celestijnenlaan 300B B-3001 Leuven Belgium Czech Tech Univ Fac Mech Engn Ctr Adv Aerosp Technol Dept Instrumentat & Control Engn Technicka St 4 Prague 16607 6 Czech Republic

The authors present an integrated approach for designing low-order multi-objective controllers for linear time-delay systems (TDSs), combining recently developed methods for reduction of delay systems and fixed-order control design, respectively. As a benchmark problem for process control applications, a model of an experimental heat transfer setup is used, which serves to motivate the adopted combination of model reduction and control technique. The former corresponds to a Krylov based reduction procedure, which is generalised to multiple-input-multiple-output systems with state, input and output delays, and allows the adaptive construction of an accurate low-order linear time-invariant approximation of the original linear TDS. Concerning the latter, a fixed-order controller is synthesised for the delay-free approximation, exploiting a recently proposed linear matrix inequality based framework for fixed-order controller design, and validated on the original model. In this way, the systematic overall design procedure, which is grounded in convex optimisation, complements approaches based on directly optimising stability and performance measures as a function of the controller parameters, which may lead to highly nonconvex, even non-smooth optimisation problems. The successful design of a fixed-order multi-H 2 controller is validated on the benchmark problem, confirming the potential of the adopted approach for realistic industrial applications.

关键词： Optimisation techniques heat exchanger multiple-input-multiple-output systems convex programming model reduction Multivariable control systems convex optimisation heat exchangers Control of heat systems stability control system synthesis Stability in control theory TDS Control system analysis and synthesis methods fixed-order multicontroller MIMO systems heat transfer process control applications low-order linear time-invariant approximation output delays linear time-delay systems linear systems reduced modelling state delays stability optimization linear algebra (numerical analysis) delays input delays Interpolation and function approximation (numerical analysis) fixed-order control design approximation theory reduced order systems linear matrix inequalities Krylov-based reduction procedure experimental heat-transfer setup linear matrix inequality-based framework low-order multiobjective controllers control technique delay-free approximation Distributed parameter control systems systematic overall design procedure

来源：评论

学校读者我要写书评

暂无评论

Tobit Kalman filter with time-correlated multiplicative measurement noise

引用

IET CONTROL theory AND applications 2017年第1期11卷 122-128页

作者： Li, Wenling Jia, Yingmin Du, Junping Beihang Univ BUAA Res Div 7 Beijing 100191 Peoples R China Beihang Univ BUAA Ctr Informat & Control Beijing 100191 Peoples R China Beihang Univ BUAA Sch Automat Sci & Elect Engn Beijing 100191 Peoples R China Beijing Univ Posts & Telecommun Sch Comp Sci & Technol Beijing 100876 Peoples R China

Kalman filters for discrete-time linear systems with censored measurements have been developed, of which the Tobit Kalman filter has been shown an effective candidate. In this study, the authors expand the Tobit Kalman filter to discrete-time linear systems with time-correlated multiplicative measurement noise. By introducing several new terms including the estimates for the products of multiplicative measurement noise and the state as well as their error covariance matrices, the proposed filter can be implemented in a recursive manner. A numerical example involving radar tracking is provided to show the effectiveness of the proposed filter.

关键词： linear systems Tobit Kalman filter Kalman filters covariance matrices radar tracking discrete time systems Discrete control systems Radar equipment, systems and applications algebra Filtering methods in signal processing error covariance matrices Signal processing theory discrete-time linear systems time-correlated multiplicative measurement noise

来源：评论

学校读者我要写书评

暂无评论

Quasi-HSS iteration methods for non-Hermitian positive definite linear systems of strong skew-Hermitian parts

引用

numerical linear algebra WITH applications 2018年第4期25卷

作者： Bai, Zhong-Zhi Chinese Acad Sci Acad Math & Syst Sci Inst Computat Math & Sci Engn Comp State Key Lab Sci Engn Comp POB 2719 Beijing 100190 Peoples R China

For large sparse non-Hermitian positive definite linear systems, we establish exact and inexact quasi-HSS iteration methods and discuss their convergence properties. numerical experiments show that both iteration methods are effective and robust when they are used either as linear solvers or as matrix splitting preconditioners for the Krylov subspace iteration methods. In addition, these two iteration methods are, respectively, much more powerful than the exact and inexact HSS iteration methods, especially when the linear systems have nearly singular Hermitian parts or strongly dominant skew-Hermitian parts, and they can be employed to solve non-Hermitian indefinite linear systems with only mild indefiniteness.

关键词： convergence Hermitian and skew-Hermitian splitting iteration method preconditioning system of linear equations

来源：评论

学校读者我要写书评

暂无评论

Parameter-dependent preview control with robust tracking performance

引用

IET CONTROL theory AND applications 2017年第1期11卷 38-46页

作者： Li, Li Liao, Fucheng Univ Sci & Technol Beijing Sch Math & Phys Beijing 100083 Peoples R China

The problem of static output feedback preview tracking control is proposed for a class of polytopic uncertain discrete-time systems by combining parameter-dependent Lyapunov function method with linear matrix inequality (LMI) technique. First, the error system method of preview control theory is adopted and the difference operator is introduced, and then an augmented error system including previewed information is constructed, which transforms a tracking problem into a regulation problem. Then, a previewable reference signal is fully utilised through reformulation of the output equation for the derived augmented error system while considering the output feedback. Sufficient conditions for designing a robust static feedback preview controller are given in terms of solutions to a set of LMIs. Based on the criterion, a static output feedback controller with preview action is designed such that the output can asymptotically track the reference signal. Finally, the numerical simulation examples also illustrate the superiority of the desired preview controller for the uncertain system in the study.

关键词： parameter-dependent Lyapunov function method numerical simulation Stability in control theory augmented error system linear matrix inequality static output feedback preview tracking control previewable reference signal robust control polytopic uncertain discrete time systems feedback algebra Lyapunov methods robust tracking performance uncertain systems linear matrix inequalities parameter-dependent preview control preview control theory Discrete control systems robust static feedback preview controller LMI technique discrete time systems

来源：评论

学校读者我要写书评

暂无评论

Sampling Type Reconstruction Processes for the Disk algebra 12

Sampling Type Reconstruction Processes for the Disk Algebra

引用

12th International conference on Sampling theory and applications (SAMPTA)

作者： Boche, Holger Pohl, Volker Tech Univ Munich Lehrstuhl Theoret Informat Tech D-80333 Munich Germany

ISBN: (纸本)9781538615652

This paper considers the classical problem of recovering functions in the disk algebra from discrete samples taken at the unit circle by means of linear sampling type approximation methods. The paper characterizes subspaces of the disk algebra on which linear approximation operators do exist and subspaces on which such operators do not exist. The subspaces on which a linear signal recovery is possible are characterized by a sufficient concentration of the signal energy in the low frequency components of the signal.

关键词： Disk algebra sampling uniform recovery

来源：评论

学校读者我要写书评

暂无评论

Domain decomposition preconditioners for multiscale problems in linear elasticity

引用

numerical linear algebra WITH applications 2018年第5期25卷

作者： Buck, Marco Iliev, Oleg Andrae, Heiko Fraunhofer Inst Ind Math ITWM D-67663 Kaiserslautern Germany Univ Kaiserslautern Dept Math Kaiserslautern Germany Univ Kaiserslautern Dept Mech Engn Kaiserslautern Germany Bulgarian Acad Sci Inst Math & Informat Sofia Bulgaria

We analyze two-level overlapping Schwarz domain decomposition methods for vector-valued piecewise linear finite element discretizations of the PDE system of linear elasticity. The focus of our study lies in the application to compressible, particle-reinforced composites in 3D with large jumps in their material coefficients. We present coefficient-explicit bounds for the condition number of the two-level additive Schwarz preconditioned linear system. Thereby, we do not require that the coefficients are resolved by the coarse mesh. The bounds show a dependence of the condition number on the energy of the coarse basis functions, the coarse mesh, and the overlap parameters, as well as the coefficient variation. Similar estimates have been developed for scalar elliptic PDEs by Graham et al. 1 The coarse spaces to which they apply here are assumed to contain the rigid body modes and can be considered as generalizations of the space of piecewise linear vector-valued functions on a coarse triangulation. The developed estimates provide a concept for the construction of coarse spaces, which can lead to preconditioners that are robust with respect to high contrasts in Young's modulus and the Poisson ratio of the underlying composite. To confirm the sharpness of the theoretical findings, we present numerical results in 3D using vector-valued linear, multiscale finite element and energy-minimizing coarse spaces. The theory is not restricted to the isotropic (Lame) case, extends to the full-tensor case, and allows applications to multiphase materials with anisotropic constituents in two and three spatial dimensions. However, the bounds will depend on the ratio of largest to smallest eigenvalue of the elasticity tensor.

关键词： coefficient robustness convergence analysis energy-minimizing basis linear elasticity multiscale finite elements overlapping domain decomposition preconditioners

来源：评论

学校读者我要写书评

暂无评论

Integral-based event-triggered PD control for systems with network-induced delay using a quadratic generalised free-weighting matrix inequality

引用

IET CONTROL theory AND applications 2017年第18期11卷 3261-3268页

作者： Koo, Baeyoung Kwon, Wookyong Lee, Sangmoon Pohang Univ Sci & Technol Grad Inst Ferrous Technol 77 Cheongam Ro Pohang Kyungpook South Korea Kyungpook Natl Univ Dept Elect Engn Daehak Ro 80 Bukgu 41566 Daegu South Korea

This study investigates event-triggered proportional-derivative (PD) control for systems with network-induced delay. Based on the Lyapunov-Krasovskii functional, the PD sampled-data controller design condition is derived in terms of linear matrix inequality (LMI) which include the integral-based event-triggering condition. As the derivative term of the proposed PD control may lead excessively frequent triggering, an integral-based triggering is firstly adopted to reduce the required sampled control input in this study. The proposed triggering condition with integration is converted as LMI with quadratic augmented vector by applying a new quadratic generalised free-weighting matrix inequality which provides a free selectable vector. numerical simulation shows the effectiveness of the proposed event-triggered PD control with the integral-based event-triggering condition.

关键词： integral-based event-triggering condition PD control event-triggered proportional-derivative control Lyapunov-Krasovskii functional numerical simulation Stability in control theory linear matrix inequality quadratic generalised free-weighting matrix inequality LMI PD sampled-data controller design condition frequent triggering linear algebra (numerical analysis) Lyapunov methods linear matrix inequalities network-induced delay free selectable vector quadratic augmented vector integral-based event-triggered PD control integral-based triggering

来源：评论

学校读者我要写书评

暂无评论

applications of the numerical methods in mechanical engineering experimental studies

引用

IOP conference Series: Materials Science and Engineering 2020年第1期916卷

作者： E Oanta A Raicu B Menabil Constanta Maritime University Faculty of Naval Electro-Mechanics 104 Mircea cel Batran Street 900663 Constanta Romania Autoklass Center srl 133 Aurel Vlaicu Bd 900498 Constanta Romania

Tremendous advances in computer science led to important progresses in science and technology. The significant feature of a computer, to rapidly and accurately perform calculi, was used for several purposes; the most important influence regarded the applied mathematics concepts where it was lifted the constraint concerning the necessary volume of calculi to be minimal when solving a complex problem. Conceptual advances also influenced the experimental mechanics domain, where numerical methods or numerical solving principles were applied to solve specific problems. The paper presents three original applications of the numerical methods in experimental mechanics. Reusability of the experimental projects' results saves time and effort. For relevancy purposes many experimental studies' results are expressed as diagrams. In the first example the approximation theory is used to solve interpolation problems. The output of the data processor consists of the spline function coefficients stored as CSV files or expressed as automatically generated computer codes, ready to be included in upper level applications. The second example is a particular study included in a hybrid model of an internal combustion engine, which outputs the states of strains and stresses in its cylinder block in running conditions. The particular study presents a method to compute the linear thermal expansion coefficient in the points where the temperatures are measured and to compute the temperatures in the inaccessible points, using the values of the previously computed coefficient. The experiment used strain gage rosettes bonded in 10 measurement points. The last original example presents a method to compute the analytical functions of the isostatics using as input data the pattern of isoclinic fringes of a photoelastic model or coating. Deep integration of the analytical, numerical and experimental studies is an important target in hybrid modelling.

关键词：

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：