基于多体系统理论的机床运动学仿真与应用研究

从多体系统运动学理论的角度, 构建了机床各部件之间的拓扑结构和约束关系, 建立了三维多体模型, 开发了运动学仿真系统. 设计者可在虚拟环境下观察到整个机床的运动加工过程, 准确了解零部件的位置、速度和加速度等运动参数, 判断零部件的姿态, 并可在样机试制前对设计中可能出现的问题作出精确的预测和改进, 保证设计方案的可行性, 缩短产品的研制周期和降低成本. 该仿真系统用于CK1416高速高精度数控车床的设计, 所得到的滚珠丝杆角速度曲线、拖板位移曲线与理论结果一致, 从而证明了模型的正确性.     

自由圆管在横向冲击载荷下的动力学行为研究

对自由圆管在其中心部位经受刚性平头弹体横向冲击时的动力学行为进行了实验研究和计算机仿真.研究了不同管径、管长以及不同材质的自由圆管在3种不同直径和质量的平头弹体的横向冲击下的变形历程、最终的变形模态以及能量的分配方式,得到了自由圆管被穿透时子弹的临界速度和临界动能.并把实验和模拟的结果与自由梁模型的情况作了比较和分析.     

IFS分形图的透视变换模拟

在给定IFS码的基础上,应用透视变换的方法将三维空间上的分形投影到二维屏幕上加以显示,并通过参数调整产生大量具有特殊视觉效果的分形图,研究了参数变化时分形图的演化.     

Simulation study on fluctuant flow stress scale effect

INTRODUCTION With the continuous development of science and technology, especially the rapid progress of electronic industry and micromachine, microparts are needed more and more, and their technical requirements are higher and higher (Geiger et al., 1994; 1996; Geiger and Engel, 2002). However, traditional processing technologies, like cutting, etc., do not meet these requirements. Traditional plastic forming technology has merits like high production rate, excellent me-chanical proper…     

基于VHDL的数字计时器的设计

文章论述了数字计时器的设计原理、设计步骤以及用VHDL语言设计数字计时器的方法。数字计时器的设计主体是计数部分和译码部分,仿真结果表明,设计的计时器精度高。     

MATLAB软件在物流运输定量分析中的应用

物流定量分析过程中通常涉及大量的数学运算,运输最优模型的研究一直是物流领域中最令人关注的问题之一。在众多的定量分析方法中线性规划法的使用最为频繁,而运输问题所涉及的条件变量众多给运算带来了极大的障碍,本文以物流运输规划中一个典型的案例为突破口阐述了MATLAB软件在物流运输定量分析过程中的应用。     

基于Ad Hoc网络的典型路由协议的研究与NS2仿真

目前Ad Hoc网络有三种典型的路由协议,即先发性（Proactive）路由协议、反应性（Reactive）路由协议和混合性（Hybrid）路由协议。本文分析了上述协议,并给出几个典型的路由协议NS2仿真分析。     

移动通信电波传播预测模型选择研究

能否准确预测基站信号的覆盖情况是移动通信网络规划的优劣所在,提高预测准确度的关键在于选择最能接近实测值的预测模型,通过对五种预测模型的分析对比,并与实测数据的仿真比较,得出了在郊区环境下,Okumura-Hata预测模型更接近实测值的结论。     

Simultaneous perturbation stochastic approximation algorithm combined with neural network and fuzzy simulation

In order to solve three kinds of fuzzy programm model, fuzzy chance-constrained programming mode ng models, i.e. fuzzy expected value and fuzzy dependent-chance programming model, a simultaneous perturbation stochastic approximation algorithm is proposed by integrating neural network with fuzzy simulation. At first, fuzzy simulation is used to generate a set of input-output data. Then a neural network is trained according to the set. Finally, the trained neural network is embedded in simultaneous perturbation stochastic approximation algorithm. Simultaneous perturbation stochastic approximation algorithm is used to search the optimal solution. Two numerical examples are presented to illustrate the effectiveness of the proposed algorithm.     

Effects of un-transposed UHV transmission line on fault analysis of power systems

The conventional fault analysis method based on symmetrical components supposes that the three-phase parameters of un-transposed transmission line are symmetrical in case of fault. The errors caused by the method with the symmetrical distributed parameter circuit model as the equivalent circuit of the un-transposed ultra high voltage (UHV) transmission line were studied under both normal operation and fault, and the corresponding problems arising were pointed out. By contrast with electromagnetic transient and power electronics (EMTPE) simulation results with the asymmetrical distributed parameter circuit model of un-transposed line, it is shown that the conventional method cannot show the existence of negative and zero sequences before fault happening and there are many errors on voltage and current after fault happening which are different with fault types. The error ranges of voltage and current are 2.13%-81.13% and -7.82%-86.15%, respectively.