An effective-charge model for the trapping of impurities of fluids in channels with nanostructured walls

We present model equations for the trapping and accumulation of particles in a cylindrical channel with nanostructured inner walls when a fluid passes through, carrying a moderate load of impurities. The basic ingredient of the model is the introduction of a phenomenological ‘effective-charge density’ of the walls, related to the electrical charges exposed in the nanotexture. The effective charge is gradually reduced as the flow runs through the channel and the trapped impurities cover the internal walls. Based on the proposed equations, the position and time dependence of the areal density of trapped impurities, and the filtration performance, may be calculated. It is proposed that experimentally testing these results may help to understand the enhanced trapping capability observed in many diverse nanotextured channel structures.     

高效预应力砼结构经济效益与大开间住宅建筑体系选择

通过工程实例的经济分析,评述高效预应力砼结构的推广价值,并提出最适合于大开间住宅的高效预应力结构体系。     

五自由度3D打印并联机器人设计及分析

为实现多向3D打印,设计了一种新型五自由度3D打印并联机器人,该机器人具有两个转动自由度和三个平动自由度,其特点是采用铰接的动平台以获得大的工作空间。根据建立的运动学模型,计算了该机器人机构的运动学反解,分析了定姿态位置工作空间和定位置姿态工作空间,用螺旋理论方法建立了速度雅可比矩阵,在此基础上分析了五自由度3D打印并联机器人的奇异性、灵巧性,并进行了运动仿真分析。研究结果表明,所设计的五自由度3D打印并联机器人具有大的位置工作空间和姿态工作空间,该机器人在工作空间内存在奇异位置,通过添加冗余驱动后可以消除奇异位置,并且具有良好的灵巧性,适合多向3D打印。     

大位移多折叠梁静电驱动器的设计及力学性能分析

针对现有微静电梳状谐振器用作驱动器时输出位移极小的弱点,提出一种结构新颖、输出位移大、能工作于谐振状态和静电力状态下的多折叠梁微静电驱动器设计方案.建立该驱动器的力学分析模型,给出位移、弹性系数和谐振频率的解析公式.研究表明,当特征尺寸相同时,与常用的直脚型和蟹脚型谐振器相比,在相同电压下其输出位移可提高7倍～14倍,而在相同最大应力条件下其位移输出能力可提高4倍～9倍.     

A THRESHOLD MODEL FOR LASER CLEANING OF LARGER SILICON WAFERS

High cleaning quality for silicon wafers without damage is a challenge in laser cleaning technologies. Laser cleaning of Al₂O₃ micro-particles, which are the main contaminants of silicon wafer lapping and polishing solutions used in industry, from silicon wafers was studied for determining laser energy for high efficient particle removal while not causing damage to the wafers. As the cleaning force is generated from laser-energy absorption and conduction of the wafer, heat-conduction model on silicon wafer was developed during laser irradiation using a finer finite element method, from which cleaning force exerting on the particles greater than the adhesion force between the particle and the substrate, but less than the wafer damage energy of laser input was determined. Calculations of the laser energy threshold values for both particle cleaning and wafer damage were conducted for silicon wafers of 200 mm in diameter and 0.2 mm in thickness, and they were found to be about 60 mJ/cm² and 320 mJ/cm², respectively. The laser energy threshold model was finally verified experimentally using a KrF Excimer laser and found to be in good agreement with the experimental data. With the cleaning parameters from the model, the cleaning efficiency of as high as 98% has been achieved.     

机车发动机机体维修用组合镗床

介绍了大工件多孔位专用组合镗床的总体方案并分析其经济效益。     

低温大平板热导装置研制及材料测试分析

介绍了作者单位研制的低温大平板热导装置的特点，关键技术，装置的构成及对一些问题的探讨，利用这套装置做一些材料的测试分析工作。     

大粒径钢纤维混凝土劈拉性能研究

基于水利工程中对大粒径混凝土的防裂增韧要求,进行了二级配骨料钢纤维混凝土试件的劈拉试验,探讨了钢纤维体积率(钢纤维掺量)对混凝土劈拉强度的影响,提出丁提高钢纤维对混凝土劈拉强度影响系数的思路和劈拉强度的计算公式.结果表明:钢纤维对二级配混凝土劈托强度有良好的增强效果.     

自动化测试浅析

本文阐述了自动化测试的概念及实现自动化测试的方法,并介绍了主流自动化测试软件及其自动化测试框架的构造,最后简单介绍了用自动化测试脚本语言Tcl实现一硬件系统中主备板间的自动切换的测试事例。     

基于自组织特征映射的网页分类研究

本文提出了一种SOFM（自组织特征映射）与LVQ（学习矢量量化）相结合的分类算 法，利用一种新的网页表示方法，形成特征向量并应用于网页分类中．该方法充分利用了SO FM自组织的特点，同时又利用LVQ解决聚类中测试样本的交迭问题．实验表明它不仅具有较 高的训练效率，同时有比较好的查全率和查准率．