Auto CAD 参数化绘图模块库的建立

介绍了ＡｕｔｏＣＡＤ软件的几种扩充方式，提出了用ＡｕｔｏＣＡＤ内部的Ｃ语言开发系统ＡＤＳ建立绘图模块库的方法。利用该绘图模块库可以简便地编制各种机械零件工作图的绘图程序，将绘图应用程序编译成可执行文件在ＡｕｔｏＣＡＤ环境下运行，从而既利用了ＡｕｔｏＣＡＤ环境强大的图形显示和编辑功能，又利用了Ｃ语言的结构化编程、运行效率高的优势，并可达到参数化绘图的目的。     

有限元模型修正中若干重要问题

本文论述线性常系数系统的有限元模型修正中的若干重要问题。这些问题里：模态形状的映射，模型降阶，参数化和正则化，以及有限元模型修正中的贝叶斯概率方法。     

一类不确定系统的重复学习控制方法

针对一类不确定非线性系统, 结合Backstepping方法, 设计重复学习控制方法.采用Lyapunov-like综合, 设计重复学习控制器处理系统中的参数和非参数不确定性, 可实现系统状态在整个作业区间上完全跟踪期望轨迹.分别讨论部分限幅和完全限幅学习机制, 证明闭环系统中各变量的一致有界性以及跟踪误差的一致收敛性.仿真结果验证了所提出控制方法的有效性.     

A novel adaptive control approach for nonlinearly parameterized systems

Nonlinearly parameterized systems are commonly encountered in control of practical systems. However, the conventional adaptive estimation and control strategies, based on the essential assumption of linear parameterization, are incapable of dealing with this class of systems. This incapability in turn becomes a bottleneck for prevalent applications of adaptive control. In literature, there have been some attempts to break through this bottleneck by investigating the characteristics of nonlinearities. However, it is still open for an implementable strategy that is powerful for nonlinearly parameterized systems as the certainty equivalence principle for linearly parameterized systems. This paper aims to contribute an attempt to this open problem by proposing a novel adaptive control approach. On the one hand, the controller is conceptually simple, and it does not explicitly rely on the expression of system nonlinearities. On the other hand, the controller is able to achieve system stability and parameter convergence. Copyright © 2013 John Wiley & Sons, Ltd.     

基于3D参数化技术的旋转导向钻具虚拟设计

在简述旋转导向钻井工具结构原理和 4个设计难点之后 ,阐述了利用SolidWorks软件进行 3D参数化设计的原理。结合旋转导向钻井工具的结构特征 ,详细论述了对这种工具进行参数化设计的总体方案设计和设计过程 ,其中包括零件设计、装配体设计和工程图生成。设计实践表明 ,利用SolidWorks软件平台缩短了旋转导向钻井工具的开发周期 ,提高了设计质量 ,降低了设计成本。该导向工具的实际加工和装配过程 ,也表明这种虚拟设计的合理性。     

Properness and Inversion of Rational Parametrizations of Surfaces

 In this paper we characterize the properness of rational parametrizations of hypersurfaces by means of the existence of intersection points of some additional algebraic hypersurfaces directly generated from the parametrization over a field of rational functions. More precisely, if V is a hypersurface over an algebraically closed field ? of characteristic zero and is a rational parametrization of V, then the characterization is given in terms of the intersection points of the hypersurfaces defined by x _i q _i (tˉ)−p _i (tˉ), i=1,...,n over the algebraic closure of ?(V). In addition, for the case of surfaces we show how these results can be stated algorithmically. As a consequence we present an algorithmic criteria to decide whether a given rational parametrization is proper. Furthermore, if the parametrization is proper, the algorithm also computes the inverse of the parametrization. Moreover, for surfaces the auxiliary hypersurfaces turn to be plane curves over ?(V), and hence the algorithm is essentially based on resultants. We have implemented these ideas, and we have empirically compared our method with the method based on Gr?bner basis. Received: November 20, 2000; revised version: November 20, 2001     

Coprime factorizations and stability of fractional differential systems

We give a frequency-domain approach to stabilization for a large class of systems with transfer functions involving fractional powers of s. A necessary and sufficient criterion for BIBO stability is given, and it is shown how to construct coprime factorizations and associated Bézout factors in order to parametrize all stabilizing controllers of these systems.     

有理三次Bezier曲线表示圆弧的一种实用方法

在圆弧的标准型有理二次贝齐尔表示的基础上,给出了圆弧的带参数的标准型有理三次贝齐尔一种更实用的表示形式,通过调节参数的值,就可以得到同一圆弧不同的标准型有理三次贝齐尔表示。就参数对内控制点、两内权因子及肩点的影响进行了详细分析,从而对圆弧的标准型有理三次贝齐尔形式表示的内在性质有了更深入的了解。     

CAE优化技术在车辆前期研发中的应用

为克服车辆传统研发方法的缺陷,即在设计早期对产品性能有较大影响的结构设计缺少考虑,导致设计中、后期须进行大量反复修改的问题,将CAE优化技术引入车辆前期研发中.介绍CAE优化技术在车辆前期工程设计中的应用和研发流程,通过参数化建模和网格变形等技术的应用实例,展示在车辆概念设计阶段提取设计变量的方法.CAE优化技术能实现...