检索结果-南通市图书馆

Output Tracking for One-Dimensional wave equation with Non-Collocated Control and Output Configuration

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2020年第5期33卷 1469-1484页

作者： WEI Jing FENG Hongyinping School of Mathematical Sciences Shanxi UniversityTaiyuan 030006China

This paper considers output tracking for a one-dimensional wave equation with general disturbance which includes both internal nonlinear uncertainty and external *** performance output is non-collocated to the *** disturbance is estimated by an essentially extended state observer from active disturbance rejection control and the difficulty caused by the non-collocated configuration of control and output is overcome by a proper trajectory *** output feedback law is proposed to make the tracking error be convergent to zero exponentially as time goes to *** the same time,all states of the closed-loop system are shown to be uniformly *** simulation is also presented to validate the theoretical results.

关键词： Disturbance estimation output feedback output tracking wave equation

Symmetries and conserved quantities of discrete wave equation associated with the Ablowitz-Ladik-Lattice system

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2013年第9期22卷 177-182页

作者：傅景礼宋端付昊何玉芳洪方昱 Institute of Mathematical Physics Zhejiang Sci-Tech University Department of Physics Eastern Liaoning University China Jingye Engineering Corporation Limited Shenzhen Brach

In this paper, we present a new method to obtain the Lie symmetries and conserved quantities of the discrete wave equation with the Ablowitz-Ladik-Lattice equations. Firstly, the wave equation is transformed into a simple difference equation with the Ablowitz-Ladik-Lattice method. Secondly, according to the invariance of the discrete wave equation and the Ablowitz-Ladik-Lattice equations under infinitesimal transformation of dependent and independent variables, we derive the discrete determining equation and the discrete restricted equations. Thirdly, a series of the discrete analogs of conserved quantities, the discrete analogs of Lie groups, and the characteristic equations are obtained for the wave equation. Finally, we study a model of a biological macromolecule chain of mechanical behaviors, the Lie symmetry theory of discrete wave equation with the Ablowitz-Ladik-Lattice method is verified.

关键词： symmetry invariant Ablowitz-Ladik-Lattice system wave equation

STABILITY ANALYSIS OF FINITE ELEMENT METHODS FORTHE ACOUSTIC wave equation WITH ABSORBINGBOUNDARY CONDITIONS (PART I)

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1999年第3期17卷 293-306页

作者： Xiu-min Shao Zhi-ling Lan(Institute of Mathematics, Academy of Sciences, Beijing 100080, China) 中科院数学所北京

In Part I and Part II of this paper initial-boundary value problems of the acoustic wave equation with absorbing boundary conditions are considered. Their finite element-finite difference computational schemes are proposed. The stability of the schemes is discussed and the corresponding stability conditions are given. Part I and Part II concern the first- and the second-order absorbing boundary conditions, respectively. Finally, numerical results are presented in Part II to show the correctness of theoretical analysis. (Author abstract) 7 Refs.

关键词： stability finite element methods wave equation absorbing boundary conditions

Target-oriented Q-compensated reverse-time migration by using optimized pure-mode wave equation in anisotropic media

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2023年第2期20卷 866-878页

作者： Shi-Gang Xu Qian-Zong Bao Zhi-Ming Ren Chang'an University School of Geological Engineering and GeomaticsDepartment of GeophysicsXi'anShaanxi710064China National Engineering Research Center of Offshore Oil and Gas Exploration Beijing100028China

Research on seismic anisotropy and attenuation plays a significant role in exploration geophysics. To enhance the imaging quality for complicated structures, we develop several effective improvements for anisotropic attenuation effects in reverse-time migration (Q-RTM) on surface and vertical seismic profiling (VSP) acquisition geometries. First, to suppress pseudo-shear wave artifact and numerical instability of the commonly used anisotropic pseudo-acoustic wave equations, an optimized pure P-wave dispersion relation is derived and the corresponding pure-mode wave equation is solved by combining the finite-difference and Possion methods. Second, a simplified anisotropic pure-mode visco-acoustic wave equation (PVAWE) based on standard linear solid model is established. Third, a time-dispersion correlation strategy is applied to improve the modeling accuracy. Fourth, we extend a target-oriented scheme to anisotropic attenuated modeling and imaging. Instead of the conventional wavefield modeling and RTM, the proposed approach can extract available wavefield information near the target regions and produce high imaging resolution for target structures. Last, both anisotropic surface and VSP Q-RTMs are executed by combining optimized PVAWE, time-dispersion correlation and target-oriented algorithm. Modeling examples demonstrate the advantages of our schemes. Moreover, our modified Q-compensated imaging workflow can be regarded as a supplement to the classical anisotropic RTM.

关键词： Anisotropy Attenuation Reverse-time migration wave equation Optimized algorithm Target-oriented

Periodic solutions of a semilinear variable coefficient wave equation under asymptotic nonresonance conditions

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2023年第1期66卷 79-90页

作者： Hui Wei Shuguan Ji Department of Mathematics Luoyang Normal UniversityLuoyang 471934China School of Mathematics and Statistics and Center for Mathematics and Interdisciplinary Sciences Northeast Normal UniversityChangchun130024China School of Mathematics Jilin UniversityChangchun 130012China

We consider the periodic solutions of a semilinear variable coefficient wave equation arising from the forced vibrations of a nonhomogeneous string and the propagation of seismic waves in nonisotropic *** variable coefficient characterizes the inhomogeneity of media and its presence usually leads to the destruction of the compactness of the inverse of the linear wave operator with periodic-Dirichlet boundary conditions on its *** the pioneering work of Barbu and Pavel(1997),they gave the existence and regularity of the periodic solution for Lipschitz,nonresonant and monotone nonlinearity under the assumptionηu>0(see Section 2 for its definition)on the coefficient u(x)and left the caseηu=0 as an open *** this paper,by developing the invariant subspace method and using the complete reduction technique and Leray-Schauder theory,we obtain the existence of periodic solutions for such a problem when the nonlinear term satisfies the asymptotic nonresonance *** result needs neither requirements on the coefficient except the natural positivity assumption(i.e.,u(x)>0)nor the monotonicity assumption on the *** particular,when the nonlinear term is an odd function and satisfies the global nonresonance conditions,there is only one(trivial)solution to this problem in the invariant subspace.

关键词： periodic solutions wave equation asymptotic nonresonance conditions

On Uniform Decay for Transmission Problem of Kirchhoff Type Viscoelastic wave equation

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2010年第7期26卷 1197-1206页

作者： Jeong Ja BAE Department of Mathematics Dongeui University

In this paper we consider the large time behavior of solutions to an n-dimensional transmission problem for two Kirchhoff type viscoelastic wave equations, that is, the wave propagation over bodies consisting of two physically different types of materials. One component is a simple elastic part while the other is a viscoelastic component endowed with a long range memory. We show that the dissipation produced by the viscoelastic part is strong enough to produce exponential or polynomial decay of the solution

关键词： existence of solution uniform decay wave equation boundary value problem a priori estimates

Application of wave equation theory to improve dynamic cone penetration test for shallow soil characterisation

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 289-302页

作者： Miguel Angel Benz Navarrete Pierre Breul Roland Gourvès Sol Solution Géotechnique Réseaux ZA des Portes de Riom Nord23 Avenue Georges GershwinRiom Cedex63204France UniversitéClermont Auvergne Institut PascalUMR CNRS 6602Clermont-Ferrand63000France Polytech Clermont-Ferrand Campus des Cézeaux 2 Avenue Blaise PascalAubière Cedex63178France

Among the geotechnical in situ tests,the dynamic penetration test(DPT)is commonly used around the ***,DPT remains a rough technique and provides only one failure parameter:blow count or cone *** paper presents an improvement of the dynamic cone penetration test(DCPT)for soil characterisation based on the wave equation *** on an instrumented lightweight dynamic penetrometer driving with variable energy,the main process of the test involves the separation and reconstruction of the waves propagating in the rods after each blow and provides a dynamic cone load-penetration(DCLT)*** analytical methodology is used to analyse this curve and to estimate additional strength and deformation parameters of the soil:dynamic and pseudo-static cone resistances,deformation modulus and wave *** carried out in the laboratory on different specimens(wood,concrete,sand and clay)in an experimental sand pit and in the field demonstrated that the resulting DCLT curve is reproducible,sensitive and reliable to the test conditions(rod length,driving energy,etc.)as well as to the soil properties(nature,density,etc.).Obtained results also showed that the method based on shock polar analysis makes it possible to evaluate mechanical impedance and wave velocity of soils,as demonstrated by the comparisons with cone penetration test(CPT)and shear wave velocity measurements made in the *** technique improves the method and interpretation of DPT and provides reliable data for shallow foundation design.

关键词： In situ test Dynamic cone penetrometer P.A.N.D.A. wave equation wave decoupling Dynamic cone load-penetration(DCLT)curve

Energy Decay for the Cauchy Problem of the Linear wave equation of Variable Coeffcients with Dissipation

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2010年第1期31卷 59-70页

作者： Pengfei YAO Key Laboratory of Control and Systems Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Decay of the energy for the Cauchy problem of the wave equation of variable coefficients with a dissipation is considered. It is shown that whether a dissipation can be localized near infinity depends on the curvature properties of a Riemannian metric given by the variable coefficients. In particular, some criteria on curvature of the Riemannian manifold for a dissipation to be localized are given.

关键词： wave equation Riemannian metric Localized dissipation near infinity

On a Strongly Damped wave equation for the Flame Front

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2010年第6期31卷 819-840页

作者： Claude-Michel BRAUNER Luca LORENZI Gregory I. SIVASHINSKY Chuanju XU School of Mathematical Sciences Xiamen University 361005 Xiamen Fujian China Dipartimento di Matematica Università degli Studi di Parma Viale Parco Area delle Scienze 53/A 43124 Parma Italy School of Mathematical Sciences Tel Aviv University 69978 Tel Aviv Israel

In two-dimensional free-interface problems, the front dynamics can be modeled by single parabolic equations such as the Kuramoto-Sivashinsky equation (K-S). However, away from the stability threshold, the structure of the front equation may be more involved. In this paper, a generalized K-S equation, a nonlinear wave equation with a strong damping operator, is considered. As a consequence, the associated semigroup turns out to be analytic. Asymptotic convergence to K-S is shown, while numerical results illustrate the dynamics.

关键词： Front dynamics wave equation Kuramoto-Sivashinsky equation Stability Analytic semigroups Spectral method