Superior step-size theorem and its application——Parallel variable step-size LMS filters algorithm

In several branches of adaptive filtering algorithms, the least mean square (LMS) algorithm is widely applied in many areas because of its low computational cost, good numerical stability and other features[1]. However, the contradiction between faster convergence and smaller steady-state mean squared error (MSE) affects its performance considerably. Step-size, as the key to the problem, can but offer only one choice of the two demands. Therefore, many variable step-size algorithms were prop…     

Parallel and Systolic Solution of Normalized Explicit Approximate Inverse Preconditioning

A new class of normalized approximate inverse matrix techniques, based on the concept of sparse normalized approximate factorization procedures are introduced for solving sparse linear systems derived from the finite difference discretization of partial differential equations. Normalized explicit preconditioned conjugate gradient type methods in conjunction with normalized approximate inverse matrix techniques are presented for the efficient solution of sparse linear systems. Theoretical results on the rate of convergence of the normalized explicit preconditioned conjugate gradient scheme and estimates of the required computational work are presented. Application of the new proposed methods on two dimensional initial/boundary value problems is discussed and numerical results are given. The parallel and systolic implementation of the dominant computational part is also investigated.     

The implementation of generic smart pointers for advanced defensive programming

Smart pointers denote a well‐known technique for collective resource ownership, e.g. sharing dynamic object instances, while usually supporting automatic garbage collection based on reference counting. The original method has been retargeted to serve as a generic defensive programming method for ‘exhaustive tracking’ of erroneous pointer use in C++. Automatic bug tracking is supported in a unified manner both for pointers to heap memory, i.e. free storage, as well as for pointers to stack or global memory, i.e. auto or static storage. Overall, the presented technique (a) offers a simple contract for memory allocation and use; (b) supports type and indirection depth genericity; (c) implements most operators supported for built‐in pointers with embedded bug defense; (d) offers an alternative way of employing a garbage collection facility for memory leak detection; and (e) provides an appropriate collection of utility macros, through which defensive pointers should be used, with an alternative version re‐targeted to normal native pointers. Copyright © 2004 John Wiley & Sons, Ltd.     

A parallel computing application of the genetic algorithm for lubrication optimization

This study investigated the performance of parallel optimization by means of a genetic algorithm (GA) for lubrication analysis. An air-bearing design was used as the illustrated example and the parallel computation was conducted in a single system image (SSI) cluster, a system of loosely network-connected desktop computers. The main advantages of using GAs as optimization tools are for multi-objective optimization, and high probability of achieving global optimum in a complex problem. To prevent a premature convergence in the early stage of evolution for multi-objective optimization, the Pareto optimality was used as an effective criterion in offspring selections. Since the execution of the genetic algorithm (GA) in search of optimum is population-based, the computations can be performed in parallel. In the cases of uneven computational loads a simple dynamic load-balancing scheme is proposed for optimizing the parallel efficiency. It is demonstrated that the huge amount of computing demand of the GA for complex multi-objective optimization problems can be effectively dealt with by parallel computing in an SSI cluster.     

基于LAPIC并联机器人的群钻外刃的锥面刃磨法

在LAPIC并联机器人的特殊坐标系中，采用坐标变换法推导建立了群钻外刃的数学模型，分析了锥面刃磨原理，用矢量变换表示了在虚轴机床上实现刃磨群钻圆锥面外刃的运动方程。     

3-TPS(RRR)并联机床设计中的干涉分析

介绍了一种3-TPS(RRR)并联机床,对该机床平行约束机构的构件间、平行约束机构和并联机构间的干涉进行了详细分析,给出了相关构件间干涉判别的计算公式。通过对该机床虚拟样机的干涉检查,验证了干涉判别计算公式的正确性。这些判别公式为该机床原型样机的设计提供了依据。     

基于ADAMS的3-PTT并联机构运动学和动力学仿真

以3-PTT型并联机构为研究对象，应用ADAMS软件建立了由静平台、动平台、定长杆等构件构成的并联机构虚拟样机模型。详细论述了建模方法、模型的ADAMS描述、仿真过程，并利用该模型对3-PTT并联机构的运动学和动力学进行了仿真，实现了在计算机上仿真分析并联机构的运动和动力性能，为并联机构设计提供了一套有效的分析方法。     

SiC二极管在高频大功率电流型逆变器中的应用

针对电流型逆变器桥臂并联扩容时开关损耗较大的问题,对SiC肖特基二极管和Si快恢复二极管的正反向恢复特性、MOSFET并联均流特性以及容性状态下电流型逆变器工作过程进行了研究。提出了在电流型逆变器中用SiC肖特基二极管代替Si快恢复二极管以实现保持逆变器良好并联均流效果的同时降低逆变器损耗。分别搭建了基于Si快恢复二极管和SiC肖特基二极管的电流型逆变器实验平台以对比验证SiC肖特基二极管在系统扩容应用中实际效果。研究结果表明,在电流型逆变器中使用SiC肖特基二极管可以极大地降低逆变器损耗同时保持逆变器良好的均流效果,提高逆变器效率。     

并联机床动态特性研究的理论与实际意义

针对并联机床的研究现状 ,从刚体动力学、弹性体动力学、加工过程稳定性、加工精度等方面综述了并联机床动态特性研究的理论与实际意义 ,明确了并联机床在工程应用中亟待解决的关键技术问题     

三自由度并联姿态测量机构及其运动学参数最优化设计

提出了基于并联结构的三自由度姿态测量机构，将其连接到三自由度串联结构位置测量装置末端可以实现对被测物体六自由度位姿的综合测量。该测量机构克服了并联机构运动学正解的困难，得到运动平台姿态坐标参数的显式解。建立了基于全微分理论的姿态测量机构坐标参数误差模型，实现机构运动学参数的优化设计。误差因子分析使得机构运动学参数设计更为合理。