A new iterative order reduction (IOR) method for eigensolutions of large structures

Order reduction is a computationally efficient method to estimate some lowest eigenvalues and the corresponding eigenvectors of large structural systems by reducing the order of the original model to a smaller one. But its accuracy is limited to a small range of frequencies that depends on the selection of the retained degrees of freedom. This paper proposes a new iterative order reduction (IOR) technique to obtain accurately the eigensolutions of large structural systems. The technique retains all the inertia terms associated with the removed degrees of freedom. This hence leads to the reduced mass matrix being in an iterated form and the reduced stiffness matrix constant. From these mass and stiffness matrices, the eigensolutions of the reduced system can be obtained iteratively. On convergence the reduced system reproduces the eigensolutions of the original structure. A proof of the convergence property is also presented. Applications of the method to a practical GARTEUR structure as well as a plate have demonstrated that the proposed method is comparable to the commonly used Subspace Iteration method in terms of numerical accuracy. Moreover, it has been found that the proposed method is computationally more efficient than the Subspace Iteration method. Copyright © 2003 John Wiley & Sons, Ltd.     

WuSH—86分布式操作系统中的几个问题

本文主要论述了一个面向科学计算,支撑“异步并行算法”解题的分布式操作系统中的某些基本问题.采用一种拟层次结构的对称形式、无主从关系.对并发进程的派生调度、进程间的通信和同步、共享资源的互斥等方面的问题,提出了一些新的有效方法,致使并行解题加速效率最高达0.87.     

用于实时数据传输的滑动帧方法及其实现

根据某雷达系统对测量信号的快速传输要求,提出采用滑动帧的处理方法并在FPGA中实现,克服了传统帧处理难以满足快速传输要求的不足。阐述了滑动帧结构的构造思想,详述了滑动帧结构的特点及具体功能模块的实现。根据实际应用需求构造了滑动帧结构处理器,试验和应用结果表明设计可行有效,能充分满足实时数据传输的要求。     

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS ON HORIZONTAL OIL-GAS FLOW

Experiments were carried out to investigate the characteristics of oil-gas flow in a horizontal pipe on a large scale (with the inner diameter D = 125 mm). With the experimental data, the flow patterns were presented. Through the analyses for the flow regime transition, it was found that there was a critical superficial velocity of liquid phase for the flow regime transiting from stratified flow to slug flow. The slug flow could not occur until the superficial velocity of liquid phase was higher than the critical velocity. For the flow pattern transiting from stratified to slug flow, the transmitting velocity of gas phase decreases with the augmentation of superficial velocity of liquid phase. On the basis of the experiments, numerical simulations of different flow patterns and their transitions were performed with the use of the Volume Of Fluid (VOF) technique. The results of the computations are shown to match well with the measured data in the experiments.     

半流体润滑脂在抽油机减速箱保养中的应用

抽油机减速箱的润滑和漏失问题已经严重影响了抽油机的正常运转，引起了人们的重视。为了解决这个问题，中原油田分公司采油一厂应用了由燕化集团生产的半流体润滑脂，先后应用于20台抽油机减速箱的润滑保养，通过6个月应用与监测，发现该半流体脂的润滑及防漏效果良好。     

国有公路运输企业改革创效的现实选择

通过对公路运输企业经营实践的考察 ,介绍了国有公路运输企业改革创效的一些现实选择 ,以供运输公司经营借鉴 ,从而摆脱困境 ,取得良好业绩     

应用金属迭片挠性联轴器改造D1000-32型风机

使用液力偶合器因故障频繁，对高炉稳产、高产造成严重威胁，而且维修费用较高，对偶合器改造后，应用金属迭片挠性联轴器其故障率、维修费用都很低。     

单层多跨刚架在移动荷载作用下的影响量计算方法

讨论了桥梁、工业厂房和大型公共建筑中较多采用的单层多跨刚架在移动荷载作用下影响量的计算方法。以工程中计算连续梁的一次力矩分配法的概念和思路为基础,建立了结构中杆端真实抗转刚度和结点转角传递的概念及其相应计算公式,提出了一种单层多跨刚架超静定结构影响量的精确计算方法。算例表明,该方法较之传统的计算方法简捷,且既便于手算,也利于编制通用程序用于电算。     

开流形的曲率与拓扑

应用比较几何的方法研究了完备非紧且具有特定曲率条件的黎曼流形，证明了在一定Pinching条件限制下，流形具有有限拓扑型或者微分同胚于R^n。     

大型储罐基础非平面倾斜问题的探讨

大型储罐因基础产生非平面倾斜而影响其正常使用的情况在工程中时有发生,文章通过对某油罐工程中基础沉降观测结果的分析,探讨了储罐基础产生非平面倾斜的原因。相邻储罐之间的相互影响、充水预压未达到规范要求以及地基处理措施不当是引起储罐基础非平面倾斜的主要因素。针对相邻储罐间的相互影响,根据现行《石油化工企业设计防火规范》和《石油化工企业钢储罐地基与基础设计规范》的规定,提出以下建议:储罐布置的净距除应满足防火规范规定外,有条件时也应适当考虑对基础沉降的影响,当采用复合地基时,相邻储罐间的净距不宜小于0.6 D;当占地面积成为主要矛盾,储罐间的净距只能限制在防火规范规定的最小范围时,在地基处理时就应采取有效措施,以尽可能减少相邻储罐的相互影响。