BFRP加固墩柱柱端应力集中效应有限元分析

本文针对BFRP（玄武岩纤维）加固墩柱试验过程中柱端产生的应力集中现象,通过有限元模拟,分析柱端应力集中产生的原因,并采取相应措施减少应力集中产生对加固产生的不利影响．     

关于定位误差产生原因的探讨

本文在全面分析关于机械加工中定位误差产生原因有关例证的基础上,对工件在调整法加工中产生定位误差的原因作了较为深入的分析。并得出了判断产生定位误差的充要三条件和产生定位误差的根本原因。     

基于关系数据库表示产生式规则

本文在分析产生式规则的数据结构模型基础上,提出了利用关系数据库表示产生式规则的思路,论述了基于关系数据库表示产生式规则的具体方法。     

四里岩水库廊道裂缝分析与评价

本文对裂缝产生机理做了分析计算。认为产生裂缝是因为混凝土干缩受到基本不干缩的浆砌石阻碍后产生的拉应变超过混凝土极限拉应变所致,提出了防止产生裂缝的措施,并针对四里岩的现状提出了处理方案。     

一种改进的Apriori算法

Apriori算法是挖掘关联规则频繁项集的最有影响的算法之一,它通过连接、剪枝等步骤产生频繁项集,进而产生强关联规则。由于面临海量数据,因此将会产生大量的候选项集,尤其是候选2-项集,严重影响了挖掘的效率。提出了一种改进的算法,此算法不产生小项候选集而直接产生大项候选集,从而提高了算法的效率。     

基于可拓学的创意生成与生产研究

如何获得新产品、新项目和解决矛盾问题的创意,是很多管理者和产品创新人员的难题.本文从创意和矛盾问题的关系出发,探讨创意产生的机理和产生创意的方法,指出产生创意的理论基础就是可拓论,产生创意的方法就是可拓创新方法,介绍利用可拓学的基本思想和方法去产生创意的程序和利用计算机生产创意的可拓创意生成方法.     

混凝土结构中水化热产生温度应力的仿真分析

基于水化热产生温度应力的基本特性,利用有限元分析软件ANSYS计算出水化热在混凝土结构中产生的温度数值,并就SPF动物房建筑部分超长混凝土框架梁（83.1m）在水化热产生温度的情况下,对结构构件中产生的温度应力和应变进行仿真分析,根据分析结果总结出水化热产生不利影响的防治措施,为工程结构设计,施工以及后续的工程水化热研究工作提供理论依据和数据支撑。     

用MOS C-V技术同时确定体产生寿命和表面产生速度

本文根据线性扫描电压作用下的深耗尽高频 MOS C-V 特性,采用修正的体产生区宽度,提出了一种快速确定体产生寿命和表面产生速度的新方法。     

平行共轴三线圈产生均匀磁场的原理和计算

在亥姆霍兹线圈产生均匀磁场的基础上讨论了加入第三个线圈产生更为均匀磁场的途径 ,并分析和推导了平行共轴三线圈产生均匀磁场的设计方法     

玄武岩纤维布Whipple防护结构超高速撞击损伤分析

针对加入玄武岩纤维织物对Whipple防护结构损伤产生的影响进行了实验研究.探讨了将玄武岩纤维织物作为航天器空间碎片超高速撞击损伤防护结构的增强材料用于航天领域的可行性.实验采用的基本构形为Whipple防护结构,玄武岩纤维布按不同方案布置在结构中.实验分析表明,玄武岩纤维布的防护作用在于:其发生击穿破坏时,击穿孔处的纤维束产生的断裂和孔边处纤维束产生的变形消耗和吸收了撞击物的撞击能量;破坏时,玄武岩纤维束中逐次断裂的纤维丝与撞击物的撞击除了对撞击物产生切割作用外还在撞击物中产生高频的间歇冲击波,两者都对撞击物产生碎化作用;玄武岩纤维布自身的破坏不会再产生新的大碎片.     

用正比计数管探测单电子的试验研究

为了研究次级电子的分布规律，用充有各种不同组分和压力的气体的正比计这探测单个初妈中电子及由此引起的次级电子数目的分布情况，其结果显示了次级电子脉冲分布不是一个简单的指数分布。     

Three-dimensional discharge simulation of inductively coupled plasma (ICP) etching reactor

More and more importance has been attached to inductively coupled plasma (ICP) in semiconductor manufacture. For a deep understanding of the plasma discharge process in the etching reactor, this study made a three-dimensional simulation on the Ar plasma discharge process with the commercial software CFD-ACE, which is according to the real experiment conditions and data supplied by North Microelectronic Corporation. The error of the simulation results is in the range of ±20% with credibility. The numerical results show that the three-dimentional spatial distribution of electron density is reduced from the chamber center to the wall. The distribution of electron density, electron temperature and power deposition is related to the shape and placement of the coil.     

用分析电子显微镜研究快速凝固A18Fe4Ce3Ti合金中的未知相

本文用分析电子显微镜(AEM)对快速凝固Al-8Fe-4Ce-3Ti(重量百分比)条带中—未知相进行了会聚京电子衍射(CBED),X—射线能谱(EDS)及高分辨分析。结果表明:它属于菱方晶系,空间群为R3m,点阵常数a=1.81A(10~(-10)m),C=22.9A.[001]位向下的高分辨像显示了同会聚束一致的对称性。     

扫描电镜测试绝缘样品能量损失的物理过程

本文针对绝缘样品在扫描电镜中的负荷问题，分析了电子束轰击样品的物理过程，讨论了电子束能量损失、平均自由程和轨迹，提供了解决负荷问题的物理模型。     

超晶格中的电子谱

对多年来超晶格多量子阱中的电子谱滤波及相关研究成果进行了总结、归纳,并研究了纳米面材料的电子滤波,超晶格多量子阱中的电子谱.叙述了周期超晶格和非周期超晶格中的电子透射和反射系数,介绍了外场下超晶格中的电子谱.外界条件可引起超晶格中内建电场的变化,进而引起隧穿电流的变化.     

新型金刚石薄膜场电子发射的特性

介绍了用微波CVD法制备的一种新型低阈值电压大电流密度金刚石薄膜场发射冷阴极,阈值电压低于1.09 V/μm,场发射电流密度高达418 mA/cm²,这是目前文献中报道的最好结果之一.文中还探讨了金刚石薄膜场电子发射机制.     

Microstructure evolution of single crystal copper wires in cold drawing

The deformation microstructure evolution of single crystal copper wires produced by OCC method has been studied with the help of TEM, EBSD and OM. The results show that there are a small number of dendrites and twins in the undeformed single crystal copper wires. However, it is difficult to observe these dendrites in deformed single crystal copper wires. The structure evolution of deformed single crystal copper wires during drawing process can be divided into three stages. When the true strain is lower than 0.94, macroscopic subdivision of grains is not evident, and the microscopic evolution of deformed structure is that the cells are formed and elongated in drawn direction. When the true strain is between 0.94 and 1.96, macroscopic subdivision of grains takes place, and the number of microbands located on {111} and cell blocks is much more than that with the true strain lower than 0.94. When the true strain is larger than 1.96, the macroscopic subdivision of grains becomes more evident than that with the true strain between 0.94 and 1.96, and S-bands structure and lamellar boundaries will be formed. From EBSD analysis, it is found that part of 〈100〉 texture resulting from solidifying is transformed into 〈111〉 and 〈112〉 due to shear deformation, but 〈100〉 texture component is still kept in majority. When the true strain is 0.94, the misorientation angle of dislocation boundaries resulting from deformation is lower than 14°. However, when the true strain arrives at 1.96, the misorientation angle of some boundaries will be greater than 50°, and the peak of misorientation angle distribution produced by texture evolution is located in the range between 25° and 30°. Supported by the National Natural Science Foundation of China (Grant Nos. 50471098 and 59971033), the Natural Science Foundation of Shaanxi Province, China (Grant No. 2003E101), and the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institution of MOE, China     

Axial electron channeling statistical method of site occupancy determination

Multibeams dynamical theory of electron diffraction has been used to calculate the fast electron thickness-integrated probability density on Ti and Al sites in the γ-TiAl phase as a function of the incident electron beam orientation along [100], [110] and [011] zone axes, with the effect of absorption considered. Both of the calculation and experiments show that there are big differences in electron channeling effect for different zone axes or the same axis but with different orientations, so we should choose proper zone axis and suitable incident beam tilting angles when using the axial electron channeling statistical method to determine the site occupancies of impurities. It is suggested to calculate the channeling effect map before the experiments.     

回旋管双阳极磁控注入电子枪分析与数值计算

根据回旋管对电子枪的要求,考虑相对论效应和空间电荷效应,编制了一套大型的计算程序.利用计算机辅助设计,计算出了电极形状、电子轨迹与电子注参量.计算表明,这种电子枪具有速度零散小、层流性较好、体积小等优点.     

Microstructure and texture of electroformed copper liners of shaped charges

The microstructures of copper liners of shaped charges prepared by electroforming technique were investigated by trans-mission electron microscopy (TEM). Meanwhile, the orientations distributing of the grains in the electroformed copper liners of shaped charges was examined by the electron backscattering Kikuchi pattern (EBSP) technique. TEM observations have revealed that these electroformed copper liners of shaped charges have the grain size of about 1-3μm and the grains have a preferential orientation distribution along the growth direction. EB SP analysis has demonstrated that the as-formed copper liners of shaped charges exhibit a micro-texture,i.e. one type of fiber texture, and the preferred growth direction is normal to the surface of the liners.