Optimal structural design with indirect use of Transferred Forces

An optimal design method based on the concepts of Transferred Forces is introduced. The method uses these forces in an indirect way. The concept of reaction functional based on transferred forces is introduced. The functional approximates the structural behaviour in terms of the properties of a selected region. Using the reaction functionals, a nonlinear programming formulation and a computational method that perform sizing and topology optimization are developed. The procedure does not need structural analyses during optimization iterations. Example problems are solved with the method and the similar solutions are obtained for a refined mesh model and a different starting design. Thus, it is concluded that the new concept presented here is applicable to structural optimization problems. Received June 28, 2000     

SPARC体系结构的操作系统仿真器实现方法研究

在CPU的研制阶段通常也要同时进行操作系统的开发,为在新型CPU问世之前运行和调试目标操作系统,就必须开发支持操作系统功能的CPU仿真器。文章针对一种正在研制的基于SPARC体系结构的CPU,提出了操作系统仿真器的两种实现方案,然后对其中一种相对可行的方案进行了深入研究,并总结了开发过程中解决的一些实际问题。     

基于ATM和Internet的视频点播系统的设计与实现

本文探讨了基于ATM和Internet传输视频点播业务系统的基本原理和实验实现。该系统由业务代理器和交互工作单元组成,业务代理器控制系统内的资源分配及业务指南,交互工作单元在代理器的控制下实现各种功能转换,包括：数据传输协议转换、比特率控制、业务网关转换、业务量监测。     

基于VSAT的移动指挥系统

通过一个实例介绍基于VSAT的移动指挥系统的设计,阐述了系统的基本结构单元与数据接口,最后,指出系统建设的注意要点。     

基于模拟对象Mock Object的单元测试研究

在软件测试中,单元测试不仅能够优化软件系统设计,还大大简化了功能测试的测试量。但是在一些情况下进行单元测试比较困难,本文引入了模拟对象Mock Object的概念,利用Mock Object进行单位测试,解决了传统单元测试中存在的一些问题。     

Identification and sizing of the entirely visible rocks from a 3D surface data segmentation of laboratory rock piles

Once segmentation of 3D surface data of a rock pile has been performed, the next task is to determine the visibility of the surface rocks. A region boundary-following algorithm that accommodates irregularly spaced 3D coordinate data is presented for determining this visibility. We examine 3D surface segmentations of laboratory rock piles and determine which regions in the segmentation correspond to entirely visible rocks, and which correspond to overlapped or partially visible rocks. This is a significant distinction as it allows accurate size determination of entirely visible rocks, separate handling of partially visible rocks, and prevents erroneous bias resulting from mishandling partially visible rocks as smaller entirely visible rocks. Literature review indicates that other rock pile sizing techniques fail to make this distinction. The rock visibility results are quantified by comparison to manual surface classifications of the laboratory piles and the size results are quantified by comparison to the sieve size.     

一种基于可编程图形硬件的快速三维图像重建算法*

针对三维CT图像重建时间过长这一瓶颈问题,给出了FDK算法的几何描述,并据此导出了利用可编程图形硬件加速三维图像重建的方法,最后利用图形处理器的可编程、高精度以及并行计算等特性实现了该方法。实验结果表明,该三维图像重建方法非常有效,与原始算法相比取得了8倍左右的重建加速比。     

火力发电机组计算机监控系统高可靠性的设计

介绍了火力发电机组计算机监控系统的网络结构、软硬件设计思想及其具体实现方法。     

Work and fatigue characteristics of unsuited and suited humans during isolated isokinetic joint motions

The effects of a pressurized suit on human performance were investigated. The suit is known as an Extra-Vehicular Mobility Unit (EMU) and is worn by astronauts while working outside their spacecraft in a low earth orbit. Isolated isokinetic joint torques of three female and three male subjects (all experienced users of the suit in 1G gravity) were measured while working at 100% and 80% of their maximum voluntary torque (MVT, which is synonymous with maximum voluntary contraction (MVC)). It was found that the average decrease in the total amount of work (the sum of the work in each repetition until fatigue) done when the subjects were wearing the EMU were 48% and 41% while working at 100% and 80% MVT, respectively. There is a clear relationship between the MVT and the time and amount of work done until fatigue. Here, the time to fatigue is defined as the ending time of the repetition for which the computed work done during that repetition dropped below 50% of the work done during the first repetition. In general the stronger joints took longer to fatigue and did more work than the weaker joints. It was found that the EMU decreases the work output at the wrist and shoulder joints the most, due to the EMU joint geometry. The EMU also decreased the joint range of motion. The average total amount of work done by the test subjects increased by 5.2% (20.4%) for the unsuited (suited) case, when the test subjects decreased the level of effort from 100% to 80% MVT. Also, the average time to fatigue increased by 9.2% (25.6%) for the unsuited (suited) case, when the test subjects decreased the level of effort from 100% to 80% MVT. It was also found that the experimentally measured torque decay could be predicted by a logarithmic equation. The absolute average errors in the predictions were found to be 18.3% and 18.9% for the unsuited and suited subjects, respectively, when working at 100% MVT, and 22.5% and 18.8% for the unsuited and suited subjects, respectively, when working at 80% MVT. These results could be very useful in the design of future EMU suits and the planning of Extra-Vehicular Activity (EVA) for the future International Space Station assembly operations.     

并行化水体表面动态多分辨率物理仿真模型

大面积水体仿真中的细节捕捉较为困难,且渲染效率容易受限。为此,提出一种基于图形处理单元(GPU)的水体表面动态多分辨率物理仿真模型。采用细节层次渐进网格划分方法对水体表面进行建模,利用统一计算构架和GPU技术加速纳维-斯托克斯方程的求解。实验结果表明,随着初始网格分辨率的提高,该模型的加速比逐渐加大,在分辨率达到1 024×1 024的情况下,能保证30帧左右的渲染 效率。