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.     

基于μCLinux的NAT设备的设计与开发

NAT(网络地址翻译)技术有效地解决了IP地址紧缺的问题,为实现IPv4到IPv6的平滑过渡发挥了巨大的作用.在一个体积小、重量轻、价格低廉的嵌入式平台上实现NAT设备具有很好的实际意义.文中介绍了NAT技术的原理和实现过程,在自行设计的ARM7嵌入式硬件平台上基于μCLinux操作系统实现了NAT的功能,并通过实现其他相关功能,构建了完整的NAT设备,完成了小型网络接入Internet的方案.     

我国风机盘管技术现状分析

介绍了近年来我国在风机盘管技术领域的最新成果，在结构形式、强化传热、提高室内空气品质、降低噪音和提高自动控制水平等方面的技术进展情况，分析了目前风机盘管中存在的问题，并对今后的发展方向进行了展望。     

Mode Matching Analysis of a Tapered Coaxial Tip in a Parallel-Plate Waveguide

A tapered coaxial tip in a parallel plate waveguide is investigated. A boundary-value problem of electromagnetic scattering from a tapered coaxial monopole is solved rigorously based on the Fourier transform, eigenfunction expansion, and mode matching. Scattering parameters are represented in a series and computed to understand the behavior of the scattering in terms of the coaxial tip geometry.     

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。     

公司大门工程建设施工

大门小品建筑属多项目综合性工程。本文作者从管理者的角度 ,通过对公司大门及附属工程施工质量控制的总结 ,说明了质量控制应贯穿于工程施工的全过程     

微地震相分析在河流储层精细描述中的应用

传统地震相分析满足不了目前油田勘探开发的需要。神经网络微地震相分析将神经网络应用于高质量三维地震数据体中，可对单一反射同相轴进行波形信号分析和训练，建立模型地震道，并对实际地震道分类，进而得到在平面和剖面上精度较高的微地震相分布。采用该方法并结合测井资料，在研究区块中建立的微地震相分布图能够清晰地表现出该区块的沉积微相特征，且较好地解释了工区内2口井的产能差异，表明神经网络微地震相分析是可靠和有效的。     

钛精矿回转窑直接还原过程结圈可能性的探讨

通过煤种，入窑球冷态强度和还原过程强度，以及钛精矿与煤灰混合物的软化温度等分析探讨了钛精矿预热球团回转窑直接还原产生结圈的可能性，获得了可以避免结圈的结论。     

KMLS型立式砂泵的振动噪声产生原因及解决措施

针对KMLS型立式砂泵振动、噪声产生原因及其表现特征,提出了解决措施。通过对这些原因的分析研究,可以提供泵设计者和生产者在减少砂泵振动方面采取相应的措施,使KMLS型立式砂泵能更好的服务于用户。