Study of warpage due to P-V-T-C relation of EMC in IC packaging

There were many studies about the prediction of warpage due to thermal mismatch , . However, cure induced warpage is usually ignored and the results can be inaccurate. To minimize this problem, a thorough understanding of epoxy molding compound (EMC) with pressure-volume-temperature-cure (P-V-T-C) relation is necessary. This paper used the P-V-T-C relation of an encapsulation material to formulate the stress-strain relationship. With the help of finite element method (FEM) and mold flow analysis, warpage predictions combined with P-V-T-C relation were performed and the results show that this approach is practical. For a given P-V-T-C relation, the shrinkage direction is pointing toward the gate and maximum warpage usually occurs at the boundary of an integrated circuit (IC) package. Variation of specific volume difference along the flow direction is larger than that perpendicular to the flow direction. When temperature difference is small in thickness direction, specific volume difference in thickness direction varies only slightly.     

用磷铝杂原子固体酸催化剂合成马来酸二丁酯

以自制的磷铝杂原子固体酸催化剂催化合成了马来酸二丁酯，考察了反应时间、醇酸摩尔比、带水剂用量、催化剂用量等对酯化率的影响；同时考察了催化剂的重复使用性。对酯化产物物理性能进行了测试，其实测值与文献值相符。     

铁通资源管理系统的设计和实现

在分析铁路通信资源结构的基础上,利用地理信息系统技术、数据库技术和客户/服务器(C/S)模式,为铁通(ChinaTietong)各级分公司和运营部门提供一套较为完善的资源管理信息系统。文中分析了铁通资源的结构与资源之间的关联,介绍了系统功能、物理结构及体系结构,详细分析了数据库设计、地理信息系统和系统安全性所采用的关键技术。这套系统的应用对铁通网络管理的现代化将起到重要的推动作用。     

Chemical compositions and optical properties of HfOxNy thin films at different substrate temperatures

High-k HfO_xN_y thin films have been grown by radio frequency (rf) reactive sputtering of metal Hf target in N₂/Ar/O₂ ambient at different substrate temperatures. The chemical compositions of the films have been investigated as a function of substrate temperature by X-ray photoelectron spectroscopy (XPS). XPS measurements showed that nitrogen concentration increases with an increase in substrate temperature. Room-temperature spectroscopic ellipsometry (SE) with photon energy 0.75–6.5 eV was used to investigate the optical properties of the films. SE results demonstrated that refractive index n increases with an increase in substrate temperature. Based on TL parameters which were obtained from the best fit results used in a simulation of the measured spectra, meanwhile, we conclude that the energy band gap (E_g) decreases with an increase in substrate temperature.     

有限元数值试井解释技术在复杂断块油气藏评价中的应用

有限元数值模拟试井技术,可通过描述不同网格的瞬变压力对测试范围内各个小单元进行精细描述.综合运用解析试井、数值试井联带分析方法,将测试动态成果与地质静态成果有机结合、相互补充,可实现对复杂断块油气藏的精细描述,达到一口井搞清一个小型复杂断块油气藏的目的.     

高油价下我国石油化工的发展对策思考

改革开放20多年来，中国经济向全球展示了持续快速的增长，作为支柱产业的中国石化工业也一直保持着良好的增长势头，得到了稳定快速的发展，尤其在“十五”期间，中国的石化工业在世界石化业中的地位有了突破性的提升。     

基于Web平台的机器翻译系统

用户可以通过Internet访问和使用机器翻译系统，在线机器翻译系统可以帮助用户阅读网上外文材料。用户一般通过购买相关软件或访问提供在线翻译的网站来获取翻译服务，但是专用软件价格昂贵，或者获得的在线翻译效果不能令人满意。通过Web服务与J2EE技术的结合，提出了将机器翻译拳统包装为Web服务的机制，使企业和个人能够以较低的代价方便地享受更高质量的翻译服务。     

NUMERICAL ANALYSIS OF THE EFFECTS OF LOCAL HYDRODYNAMICS ON MASS TRANSFER IN HETEROGENEOUS POROUS MEDIA

Many engineering problems require the estimation of mass transfer coefficients in porous materials. In heterogeneous materials or in cases where mass transfer sites are not spatially uniform, empirical equations for mass transfer coefficients vary widely, and the origin of these differences is not well understood. In this article, we use a stochastic algorithm to model mass transfer from single particles in a two-dimensional heterogeneous packed bed. The computed mass transfer coefficients are used to generate a distribution of local Peclet numbers in the bed. Detailed hydrodynamics are then used to interpret variations in the local Peclet number. The results show clear relationships between pore structure, streamline patterns, and mass transfer rates.     

Engineering Computation and Analysis of Enhancing Efficiency for Folded Waveguide TWT in MMW

Large signal operating equations in TWT have been solved by numerical solve method. The relations between interaction efficiency and design parameters in TWT are analyzed. A fast engineering design method of enhancing efficiency for folded waveguide TWT by velocity resynchronization is described. The computation is shown that the efficiency of Ka-band folded waveguide TWT with double taper can be enhanced over twice as original tube. This method of approach is very useful for tube designer.