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.     

电容传感器在使用中存在的几个问题及处理方法

随着电容测量技术的迅速发展，电容传感器在非电量测量和自动检测中得到广泛应用，但它在使用过程中也存在一些问题，针对在使用电容传感器过程中存在的几个问题，从电容传感器的原理和工作过程两个方面进行了讨论，并提出行之有效的处理方法。     

Nanoscale structural characteristics and electron field emission properties of transition metal–fullerene compound TiC60 films

Transition-metal compound TiC₆₀ thin films were grown by co-deposition from two separated sources of fullerene C₆₀ powder and titanium. Study of structural properties of the films, by Raman spectroscopy, atomic force microscopy, and scanning tunneling spectroscopy reveals that the films have a deformed C₆₀ structure with certain amount of sp³ bonds and a rough surface with a large number of nanoclusters. z–V tunnelling spectroscopic measurements suggest that several charge transport mechanisms are involved in as the tip penetrates into the thin film. Conventional field electron emission (FEE) measurements show a high emission current density of 10 mA/cm² and a low turn-on field less than 8 V/μm, with the field enhancement factors being 659 and 1947 for low-field region and high-field region, respectively. By exploiting STM tunneling spectroscopy, local FEE on nanometer scale has also been characterized in comparison with the conventional FEE. The respective field enhancement factors are estimated to be 99–355 for a gap varying from 36 to 6 nm. The enhanced FEE of TiC₆₀ thin films can be ascribed to structural variation of C₆₀ in the films and the electrical conducting paths formed by titanium nanocrystallites embedded in C₆₀ matrix.     

春光油田现代油藏经营管理模式的

介绍并分析了春光油田现代油藏经营管理模式的构建与运作及实施效果.     

"十五"农村水电发展分析与"十一五"发展预测

本文分析了"十五"期间农村水电发展情况,对"十一五"农村水电发展政策环境及增长情况进行了预测。     

试论QC小组活动与企业文化建设相结合

本文分析了QC小组活动与企业文化的特点与共同点,提出开展QC小组活动与企业文化建设是互相促进,互相补充的,两者可以互相结合。     

山西沁南煤层气井试气工艺分析

对山西沁南地区三口煤层气井试气施工工艺进行总结分析，改进了注入压降测试管柱，采用电潜泵法对煤层排采测气。对今后煤层气井的施工具有一定的指导意义。     

蓄热式均热炉生产中存在问题的分析及解决方案

介绍了高温空气燃烧技术在均热炉上的应用情况，对应用中出现的问题进行了分析，并提出了解决方案。     

河北省水安全现状分析及对策探讨

从水资源与水环境两方面分析了河北省水安全的现状,指出影响水安全的因素在于自然因素、人为因素及人与自然的不协调因素,并针对水安全问题可能引发的健康安全、粮食安全、经济安全、生态环境安全进行了讨论,最后探讨了解决河北省水安全问题的对策。