单模激光系统中混沌吸引子的分维

对单模激光系统动力学行为的Ｌａｓｅｒ－Ｌｏｒｅｎｚ方程进行了线性稳定性分析,通过计算Ｌｙａｐｕｎｏｖ指数来确定该系统中混沌吸引子的分维。     

自调心伪双CCD光切360°三维轮廓测量系统

针对双 CCD三角测量系统的调心问题,提出一种利用单 CCD辅以可控机械回转臂实现光切 360°三维轮廓测量的新方案,给出了测量原理及系统结构,并详细介绍了映射函数法标定系统的原理及其具体实现.实物测量结果表明,该方法除具有双 CCD光切测量系统的全部优点外,测量系统可实现自动定心,后序数据融合简单,测量精度高,系统造价较低.     

The fractional dimension identification method of critical bifurcated parameters of bearing-rotor system

ＩｎｔｒｏｄｕｃｔｉｏｎＢｉｆｕｒｃａｔｉｏｎａｎｄｆｒａｃｔａｌｔｈｅｏｒｙａｒｅｔｗｏｉｍｐｏｒｔａｎｔｂｒａｎｃｈｅｓｏｆｎｏｎｌｉｎｅａｒｓｃｉｅｎｃｅ.Ｔｈｅｂｉｆｕｒｃａｔｉｏｎｉｓ:ｆｏｒｃｏｎｔｉｎｕｏｕｓ＿ｔｉｍｅｄｙｎａｍｉｃａｌｓｙｓｔｅｍｘ=ｆ(ｘ,ｔ,α)ｏｒｄｉｓｃｒｅｔｅｄｙｎａｍｉｃａｌｓｙｓｔｅｍｘ｜→ｇ(ｘ,α)(ｗｈｅｒｅｇｉｓｍａｐｇ:Ｒｎ×Ｒ→Ｒｎ),ｗｈｅｎｔｈｅｐａｒａｍｅｔｅｒαｃｈａｎｇｅｓｃｏｎｔｉｎｕｏｕｓｌｙａｎｄｐａｓｓｅｓα0,ｔｈｅｔｏｐｏｌｏｇｉｃ…     

粘弹性圆薄板的动力学行为

基于线性粘弹性力学的Boltzmann叠加原理,给出粘弹性圆薄板动力学分析的初边值问题。通过一定的简化后得到描述薄板力学行为的四维非线性非自治动力系统。综合使用非线性动力学中的数值分析方法,研究了参数对粘弹性圆薄板动力学行为的影响。同时计算了吸引子的Lyapunov维、相关维和点形维。     

Impact Dynamics in Milling of Thin-Walled Structures

The development of reliable high-speed spindles and motioncontrol systems has led to an increase in the industrial use ofhigh-speed milling. One of the primary applications of this newtechnology is the manufacture of thin-walled aluminum components foraircraft. The flexibility of the tools and workpieces, the high spindlefrequencies, and the inherent impact nonlinearities in the millingprocess can lead to complicated dynamic tool-workpieceinteractions. An experiment was constructed to study the vibrations ofa thin-walled part during milling. Time series, power spectra,autocorrelations, auto-bispectra, and phase portraits were examined.From this data, it is inferred that stiffness and damping nonlinearitiesdue to the intermittent cutting action have a pronounced effect on thedynamics of the workpiece. Delay space reconstructions and pointwisedimension calculations show that the associated motions arecharacterized by a fractal geometry. The auto-bispectra suggestquadratic phase coupling among the spectral peaks associated with thecutter frequency. A mechanics-based model with impact-nonlinearities wasdeveloped to explain the observed results. The predicted results agreewell with the experimental observations. The model predictions indicatethat aperiodic motions are possible over a large range ofcontrol-parameter values. These analytical and experimental results haveimplications for the prediction and control of vibrations in milling.     

An Event Dimension for Modeling Damping Due to Time-Varying Forcing Frequency

This article presents an original method for evaluating thedissipative effect in SDOF systems due to the transient phenomenongenerated by time-varying forcing frequencies. The main contributionlies in the use of an event dimension, as additional dimension, andEinstein's method for highlighting and proving the existence of adamping term in the equation of the motion. The variational problem ofthe metric of a pseudo-Riemannian space gives the geodesic equations andthe equation of the motion. The application is concerned with aspring-pendulum system and the associated experimental investigationpermits validating the method proposed. The influence of the variationof the forcing frequency is highlighted using two different load cases:it is shown that the damping depends on the forcing frequency variation.     

Set packing relaxations of some integer programs

This paper is about set packing relaxations of combinatorial optimization problems associated with acyclic digraphs and linear orderings, cuts and multicuts, and set packings themselves. Families of inequalities that are valid for such a relaxation as well as the associated separation routines carry over to the problems under investigation. Received: September 1997 / Accepted: November 1999?Published online June 8, 2000     

The packing property

A clutter (V, E) packs if the smallest number of vertices needed to intersect all the edges (i.e. a minimum transversal) is equal to the maximum number of pairwise disjoint edges (i.e. a maximum matching). This terminology is due to Seymour 1977. A clutter is minimally nonpacking if it does not pack but all its minors pack. An m×n 0,1 matrix is minimally nonpacking if it is the edge-vertex incidence matrix of a minimally nonpacking clutter. Minimally nonpacking matrices can be viewed as the counterpart for the set covering problem of minimally imperfect matrices for the set packing problem. This paper proves several properties of minimally nonpacking clutters and matrices. Received: December 1, 1997 / Accepted: April 6, 1999?Published online October 18, 2000     

关于凝聚局部环的正则性

本文证明了极大理想m是有限生成的交换凝聚局部环（R,M）是正则的充分必要条件是m可以由一个正则R-序列生成,推广了文献[1]中相应的结论并给出了一个由正则凝聚局部环构造大量的非正则凝聚局部环的方法．     

轴承-转子系统分岔参数的分维数识别法

广泛用于各行各业的转子系统的稳定性问题一直倍受关注.而在当今失稳多是由于一些非线性现象的出现所引起,这就对转子系统的设计提出了更高的要求:考虑非线性因素,避开会出现非线性现象的不稳定参数点或区域.若仅知未知系统的系列时间序列(有可能被噪声污染),如何识别系统运动性态的变化?为了探讨此问题,在本文中通过对一单盘Jeffcott转子的研究,得出了利用随参数变化的时间序列分维数趋势图,可以很好地识别轴承-转子动力系统发生分岔时的临界参数.