电动汽车用永磁同步电动机混沌振动的控制

建立非均匀气隙永磁同步电动机系统的数学模型,用系统的时间历程图、相轨迹图、庞加莱映射图、李雅普诺夫指数和功率谱图揭示混沌振动。为消除永磁同步电动机系统中的混沌振动,在此系统上施加一个非线性反馈控制器,通过选取适当的控制参数,可将原来永磁同步电动机系统中的混沌振动控制到稳定的周期运动。数值仿真结果表明该控制方法的有效性与可行性。     

纺丝聚合物熔体流变性的实验研究

采用西德布拉本达公司挤出流变仪测试纺丝聚合物熔体流变性能,该仪器用螺杆挤出机作为熔融器,为狭缝式毛细口模提供一定压力的熔体;由于熔融历程与熔融纺丝生产过程类似,因而测试所得数据更接近熔融纺丝的实际情况,实测特性粘度[η]为0.67～1.03dL/g的几种纤维级聚酯(PET)的流动特性以及若干国产及进口纤维级聚丙烯的流变特性,得到了一系列数据,这些数据将为纺丝机械设计和纺丝工艺参数设计提供依据。     

熔体泵在聚合物加工中的特性及应用

熔体泵辅助挤出已广泛应用于聚合物加工工业,在挤出机出口处安装熔体泵能有效的产生必要的压力并使熔体均匀的输送到机头。稳定的体积流量和降低熔体温度对于改善最终产品的质量有重要意义。熔体泵辅助挤出可用于片材、管材、吹膜和型材,它具有广泛的发展前景。主要介绍其在聚合物挤出系统中的特点及应用。     

混沌控制综述

混沌和混沌控制是非线性动力系统的新理论、新方法和新概念 ,是智能控制的重要组成部分。本文介绍了混沌的产生、特点及混沌控制的方法 ,阐述了混沌理论的普遍应用 ,指出混沌控制这一颇具起色的研究方向无论在理论上还是在应用方面都具有十分诱人的前景     

振动机械利用混沌振动的可行方案

分析了在振动机械中应用混沌振动的途径，基于含间隙机构的动力分析，提出了一种混沌振动机械的可行方案。     

二自由度含间隙碰撞振动系统的分岔与混沌

针对二自由度含间隙碰撞振动系统，建立了正弦激励作用下的碰撞振动方程，推导了振动系统满足稳定碰撞的周期解参数和解存在的充要条件，给出了Poincare映射的数学关系.在此基础上，进行了周期运动的稳定性分析，研究了系统随参数改变出现分叉和通向混沌运动的途径.计算结果表明，该振动系统存在复杂丰富的动力学行为.在一定的参数条件下，系统除了存在稳定的周期运动形态之外，还存在着倍周期分叉、Hopf分叉以及其他分叉，系统会沿着倍周期分叉、Hopf分叉等多种途径进入混沌运动.     

小型振动搅拌机的混沌特性

目的建立混凝土搅拌机系统力学模型与运动微分方程,分析系统运动状态．方法利用数值模拟的方法,在一定的参数下,以转速为分叉参数,结合波形图、轴心轨迹图和poincar6截面图,来分析搅拌机系统的混沌特性．结果当搅拌轴转速在工作转速范围内时,系统的宏观运动状态是周期1运动,而微观运动状态是无序的混沌运动,即系统的运动状态是周期运动中包含有比较强烈的混沌运动;当搅拌轴转速在工作转速范围之外时,系统的运动状态只是周期运动．结论在一定的参数数值下,混凝土搅拌机具有混沌运动特性,这种运动状态能较好地破坏水泥凝聚团,增加有效的碰撞次数,能有效地改善混凝土的微观匀质性．提高微观搅拌效果．     

最优控制技术在转子振动控制中的应用

本文在现有文献的基础上．分析了各种转子振动主动控制方案，采用了最优控制技术，将控制力施加于轴承座上，实现了转子振动闭环反馈控制．实验证明，控制效果是理想的．     

变量反馈控制方法在混沌控制中的应用

将变量反馈控制方法用于混沌杜芬方程的控制，通过调整反馈强度，可显著改善混沌现象，并可使系统由初始的混沌轨道被控变成非混沌的轨道，最终进入目标轨道．     

振动注射实现等规聚丙烯自增强自增韧

利用自行研制的两种振动注射装置，研究振动频率对等规聚丙烯机械性能的影响。振动频率的提高有利于试样屈服强度增加，并存在一个最大值，在强度峰值之后，振动频率的增加使屈服强度的变化不大，但总是大于常规注射得到的屈服强度值；较低的振动频率使断裂伸长率降低，之后振动频率增加有利于断裂伸长率提高；振动频率的增加明显提高冲击强度(对于振动注射Ⅰ，频率大于4．17Hz，冲击强度变化不大)。可见，振动注射可以实现聚丙烯自增强的同时自增韧。     

Stochastic Chaos with Its Control and Synchronization

The discovery of chaos in the sixties of last century was a breakthrough in concept,revealing the truth that some disorder behavior,called chaos,could happen even in a deterministic nonlinear system under barely deterministic disturbance.After a series of serious studies,people begin to acknowledge that chaos is a specific type of steady state motion other than the conventional periodic and quasi-periodic ones,featuring a sensitive dependence on initial conditions,resulting from the intrinsic randomness of a nonlinear system itself.In fact,chaos is a collective phenomenon consisting of massive individual chaotic responses,corresponding to different initial conditions in phase space.Any two adjacent individual chaotic responses repel each other,thus causing not only the sensitive dependence on initial conditions but also the existence of at least one positive top Lyapunov exponent(TLE) for chaos.Meanwhile,all the sample responses share one common invariant set on the Poincaré map,called chaotic attractor,which every sample response visits from time to time ergodically.So far,the existence of at least one positive TLE is a commonly acknowledged remarkable feature of chaos.We know that there are various forms of uncertainties in the real world.In theoretical studies,people often use stochastic models to describe these uncertainties,such as random variables or random processes.Systems with random variables as their parameters or with random processes as their excitations are often called stochastic systems.No doubt,chaotic phenomena also exist in stochastic systems,which we call stochastic chaos to distinguish it from deterministic chaos in the deterministic system.Stochastic chaos reflects not only the intrinsic randomness of the nonlinear system but also the external random effects of the random parameter or the random excitation.Hence,stochastic chaos is also a collective massive phenomenon,corresponding not only to different initial conditions but also to different samples of the random parameter or the random excitation.Thus,the unique common feature of deterministic chaos and stochastic chaos is that they all have at least one positive top Lyapunov exponent for their chaotic motion.For analysis of random phenomena,one used to look for the PDFs(Probability Density Functions) of the ensemble random responses.However,it is a pity that PDF information is not favorable to studying repellency of the neighboring chaotic responses nor to calculating the related TLE,so we would rather study stochastic chaos through its sample responses.Moreover,since any sample of stochastic chaos is a deterministic one,we need not supplement any additional definition on stochastic chaos,just mentioning that every sample of stochastic chaos should be deterministic chaos.We are mainly concerned with the following two basic kinds of nonlinear stochastic systems,i.e.one with random variables as its parameters and one with ergodical random processes as its excitations.To solve the stochastic chaos problems of these two kinds of systems,we first transform the original stochastic system into their equivalent deterministic ones.Namely,we can transform the former stochastic system into an equivalent deterministic system in the sense of mean square approximation with respect to the random parameter space by the orthogonal polynomial approximation,and transform the latter one simply through replacing its ergodical random excitations by their representative deterministic samples.Having transformed the original stochastic chaos problem into the deterministic chaos problem of equivalent systems,we can use all the available effective methods for further chaos analysis.In this paper,we aim to review the state of art of studying stochastic chaos with its control and synchronization by the above-mentioned strategy.     

预测控制在结构振动控制中的应用研究

主要研究预测控制在结构振动控制中的应用,探讨结构振动控制对象模型、预测模型、控制算法,然后通过模拟试验,证实其控制效果明显、易于实现。     

一个Van Der Pol-Duffing系统的混沌与控制

研究了Van der Pol-Duffing振子的混沌动力学行为,应用直接微扰法构造了系统的通解,由该通解获得了预测混沌出现的Melnikov判据.在非微扰情形,相图和相应Poincaré截面的演化结果表明：系统阻尼和外驱动力的变化都可以导致系统由倍周期分叉进入混沌状态,当频率参数取相同值时,系统混沌被完全抑制.     

超声波振动塑化原理模型及装置

探讨了振动对聚合物熔体的体积效应、剪切塑化作用。构建了新型熔融塑化理论，并根据塑化原理设计了多功能流变性能测试装置．对聚合物流变性能进行了测试，取得好的塑化效果，验证了塑化模型的可行性．     

干气密封环磨合过程摩擦振动信号混沌特性分析

磨合对防止干气密封环端面发生咬合、延长密封环使用寿命等具有一定影响,因而研究干气密封环在磨合过程中的变化特征,识别磨合状态有着重要意义.利用集合经验模态分解法(EEMD)提取端面间的摩擦振动信号,通过相空间重构,得到了摩擦振动信号的相轨迹和混沌参数.利用主分量分析法(PCA)和最大Lyapunov指数判别法,验证摩擦振...