检索结果-南通市图书馆

The dynamics of an ion acting on two monochromatic obliquely propagating Alfvén waves

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Plasma Science and Technology 2017年第7期19卷 12-25页

作者： Limin YU Zhengmao SHENG Xianmei ZHANG Erbing XUE Department of Physics East China University of Science and Technology Shanghai 200237 People＇s Republic of China Department of Physics and Institute for Fusion Theory and Simulation Zhejiang University Haugzhou 310027 People＇s Republic of China

The interaction between a magnetized ion and two monochromatic shear Alfvtn waves propagating obliquely to an ambient magnetic field is investigated both analytically and numerically. According to the Hamiltonian of this system, the invariant of motion at the lowest order and the half-island widths at the corresponding resonances are obtained analytically using the Lie transformation method. It is shown that these theoretical results agree with the numerical ones from the poincare surface of section. The regular motions from the invariant and the transition to stochasticity due to resonance overlapping are demonstrated. Compared to the case of a single wave, there may be a lower stochastic threshold in the multiple-wave problem.

关键词： Alfven waves Lie transformation poincare section stochastic heating

维普期刊数据库

An improved numerical method for constructing Halo/Lissajous orbits in a full solar system model

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2018年第6期31卷 1362-1374页

作者： Yingjing QIAN Xiaodong YANG Wuxing JING Wei ZHANG Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures College of Mechanical Engineering Beijing University of Technology Department of Aerospace Engineering Harbin Institute of Technology

An improved numerical method that can construct Halo/Lissajous orbits in the vicinity of collinear libration points in a full solar system model is investigated. A full solar system gravitational model in the geocentric rotating coordinate system with a clear presentation of the angular velocity relative to the inertial coordinate system is proposed. An alternative way to determine patch points in the multiple shooting method is provided based on a dynamical analysis with poincare′sections. By employing the new patch points and sequential quadratic programming, Halo orbits for L1, L2, and L3points as well as Lissajous orbits for L1and L2points in the EarthMoon system are generated with the proposed full solar system gravitational model to verify the effectiveness of the proposed method.

关键词： Full solar system model Halo orbit Libration motion Lissajous orbit poincare section

维普期刊数据库

Controlling Chaos for the Buck Converter Using a Nonlinear Controller in the Form of the Cubic Difference 36

在线全文

学校读者我要写书评

暂无评论

Controlling Chaos for the Buck Converter Using a Nonlinear C...

Chaos in a gravitational field with dipoles

第36届中国控制会议

作者： Meimei Jia School of Electric Power Jinchuan CampusInner Mongolia University of Technology

ISBN: (纸本)9781538629185

When the Buck converter is under the chaotic state, its working performance deteriorates. This paper proposes a novel nonlinear controller in the form of the cubic difference to eliminate the chaotic behavior in the Buck converter. This nonlinear controller is designed on basis of an idea that the cubic difference between the output voltage and the input voltage is multiplied by a feedback coefficient. Based on the state equations and the discrete mapping equations of the original Buck converter, it is confirmed that the chaotic phenomenon exists in the Buck converter. In terms of the controlled Buck converter model which can be obtained by introducing the nonlinear controller into the original Buck converter, the effectiveness of this controller is verified via analyzing the bifurcation diagrams with the feedback coefficient increasing, the inductor current waveform, the output voltage waveform, the poincare section, the phase portrait and so on. Results show that without knowing the targeting orbit beforehand, this controller can transform the chaotic state of the Buck converter to the fixed point and the various periodic orbits by only adjusting one external parameter, that is, the feedback coefficient. The results of this paper provide a new thought for controlling chaotic phenomena in the power electronic circuits.

关键词： Chaos control Nonlinear controller Fixed point Periodic orbit poincare section

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Physics B 2003年第8期12卷 836-840页

作者：陈菊华王永久 CollegeofPhysicsandInformationScience InstituteofPhysicsHunanNorma/UniversityChangsha410081China

In this paper we investigate the dyna nics of a test particle in the gravitational field with dipoles. At first we study the gravitational potential by numerical simulations, we find that, for appropriate parameters, there are two different cases in the potential curve: one is the one-well case with a stable critical point, and the other is the three-well case with three stable critical points and two unstable critical points. By performing poincare sections for different values of the parameters and initial conditions, we find a regular motion and a chaotic motion. From these poincare sections,we further confirm that the chaotic motion of the test particle originates mainly from the dipoles.

关键词： chaos poincare section dipole

The Axial Nonlinear Vibration Analysis of Ball-screw about Machine Tool Feeding System

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Plant Engineering and Management 2016年第3期21卷 181-192页

作者： ZENG Hao-ran LIU Nian-cong YANG Jia-rui CHEN Jian-long GENG Wei-tao College of Nuclear Technology and Automation Engineering Chengdu University of Technology

The forced state of the ball-screw of machine tool feeding system is analyzed. The ball-screw is simplified as Timoshenko beam and the differential equation of motion for the ball-screw is built. To obtain the axial vibration equation,the differential equation of motion is simplified using the assumed mode method. Axial vibration equation is in form of Duffing equation and has the characteristics of nonlinearity. The numerical simulation of Duffing equation is proceeded by MATLAB / Simulink. The effect of screw length,exciting force and damping coefficient are researched,and the axial vibration phase track diagram and poincare section are obtained. The stability and period of the axial vibration are analyzed. The limit cycle of phase track diagram is enclosed. Axial vibration has two type-center singularity distributions on both sides of the origin. The singularity attracts vibration to reach a stable state,and poincare section shows that axial vibration appears chaotic motion and quasi periodic motion or periodic motion. Singularity position changes with the vibration system parameters,while the distribution doesn’ t change. The period of the vibration is enhanced with increasing frequency and damping coefficient. Test of the feeding system ball-screw axial vibration exists chaos movement. This paper provides a certain theoretical basis for the dynamic characteristic analysis of machine feeding system ball-screw and optimization of structural parameters.

关键词： ball screw Timoshenko beam axial vibration phase diagram poincare section

维普期刊数据库

Anti-control of Hopf bifurcation creation off an unstable equilibrium point

在线全文

学校读者我要写书评

暂无评论

Anti-control of Hopf bifurcation creation off an unstable eq...