The Structure And Electrical Properties Of Dislocations In Semiconductors

Evidence from weak beam electron microscopy shows that dislocations introduced by deformation of crystals of tetrahedrally coordinated semi-conductors are dissociated into partials, and suggests that these lie on the‘glide’ rather than the‘shuffle’ planes. Models of the structures of the cores of such partials are described, and it is proposed that the bonds in the cores of the 30° and 90° partials constituting screw and 60° dislocations are reconstructed, forming one dimensional super-lattices, and that dangling bonds occur only at kinks, antiphase defects, and possibly in the cores of 60° partials constituting edge dislocations. The implications regarding electronic and optical properties are discussed briefly. Consideration of the charge carried by dislocations suggests that significant Coulomb forces between partials may arise only when Cottrell atmospheres of charged point defects or impurities are present.     

Characterization Of Grain Boundaries Observed In Polycrystalline Silicon For Solar Cell Applications

This paper describes some preliminary results concerning the TEM observations of grain boundaries in polycrystalline silicon for solar cell applications. A graphical method of grain boundary characterization has been developed. All the grain boundaries studied have been found to be characterized by twin relationships.     

Microscope Photometry In Studies Of The Molecular Structure Of Carbonized Bitumens And Pyrobitumens

Four bitumens and pyrobitumens (gilsonite, grahamite, impsonite and shungite), varying considerably in their initial properties, have been carbonized over the temperature range 0–1400 °C. Reflectances of the carbonized products in air and immersion oil were measured at 546 nm using a conventional microscope photometer, and the effective bireflectances. refractive indices and absorption coefficients calculated for the samples from the reflectances. The results obtained support an earlier suggestion that the derived optical data can be used to supplement X-ray lattice parameters as a means of tracing the general course of molecular and structural organization of organic materials when these are carbonized, viz: (a) continuously rising bireflectance and absorption coefficient with rise of preparation temperature respectively indicate progressive ordering of the aromatic lamellae and increasing average diameter of the sheets of aromatic layers forming the‘crystallites’; while (b) systematic changes of the effective refractive index point to interruptions in the growth of the heights of the aromatic-layer stacks in the crystallites. The optical variations are paralleled by changes in the patterns of the X-ray lattice parameters for the same samples, which estimate directly the aromatic-layer diameters (La), the average number of aromatic layers in the stacks (Lc) and the average spacing of the aromatic layers (d). Although the trends followed by the optical properties of the carbonized products of the bitumens and pyrobitumens are generally similar, in detail they show variations that can be related to the initial character of the fresh materials. The carbonization process, as it affects bitumens and pyrobitumens, is briefly discussed in the light of these results.     

The Measurement Of Excess Volume At Grain Boundaries Using Transmission Electron Microscopy

A technique enabling accurate measurements of relative displacements between adjacent coincidence related crystals has been described previously. The technique depends on intensity measurements of stacking-fault-like fringes by comparison of experimental and theoretically simulated fringe profiles. This matching procedure is illustrated in the present work for a (l?2l?) boundary between twin related aluminium crystals. The main part of the paper describes the application of the technique for measuring excess volume at certain coincidence boundaries, and considers in detail the measurement for (l?2l?) boundaries. The excess volume per unit area at (l?2l?) boundaries is found to be 0·02 nm.     

The Use Of The Texture Analyser To Study Sinter Structure: Application To The Morphology Of Calcium Ferrites Encountered In Basic Sinters Of Rich Iron Ores

Quantitative image analysis applied to iron ore sinters gives complementary information to chemical analysis such as quantitative mineralogical analysis, and also quantitative geometric properties of crystals and of porous networks (size distribution, repartition). Spatial disposition of sinter components produced during crystallization builds different textures which are well known to mineralogists. The types of textures encountered can be related to initial composition, cooling conditions and to physical properties of the sinter (mechanical strength, reducibility). In order to estimate the relative importance of each texture in a sinter, measurements made using a pattern recognition procedure are required. Algorithms for automatic pattern recognition were established for calcium ferrites texture encountered in rich iron ore basic sinters. They depend on a specific treatment of morphological parameters estimated inside fields of measurement of the texture analyser. Furthermore, mathematical models of multicomponent structures based on mathematical morphology, are used for different calcium ferrites textures. The parameters of these models are estimated from experimental measurements made with a texture analyser. The present study is a part of a research programme made by IRSID (Institute of Research of French Steel Industry) on the structure of iron ore sinters in order to explain variations of their physical properties related to their behaviour in the blast furnace.     

超声波萃取-气相色谱法测定鱼肉中硝基苯类化合物的不确定度评定

对超声波萃取-气相色谱法测定鱼肉中硝基苯类化合物的过程中可能引入的不确定度进行了分析和评定.结果表明不确定度主要来源为标准系列制备过程和样品制作过程引入的不确定度.     

Local Characterization Of Solids By Electron Energy Loss Spectrometry

A survey of instrumentation for electron energy loss spectrometry and applications of this technique to the local characterization of solids is presented. The use of plasmon losses and core excitation losses are compared. The statistics that determine elemental detection limits for core losses are discussed and areas for future developments in the use of electron energy loss spectrometry are emphasized.     

低温恒温仪器在头孢类抗生素合成实验中的应用

DFY低温恒温仪器采用全封闭压缩机组制冷和XMT模拟数字PID自动控制系统,工作温度范围广（-80°C-300°C）,广泛用于制药、石化、生物、化工等行业中的冷却和加热。本文对头孢反应体系使用的低温恒温仪器选型、冷载体、制冷量及冷载体更换周期进行了探讨,并通过实验进行比较分析得出结论,提出了适合头孢反应体系使用的低温恒温仪器。     

风机叶片用涂层的抗冲蚀性能的研究

针对风机叶片用涂层的抗冲蚀性能进行了研究,从磨损原理入手,分析研究了等离子喷涂涂层和表面粘涂涂层的抗冲蚀性能。采用NIWC35涂层和陶瓷耐磨修补剂（11680）涂层,对涂层结合强度、硬度、显微结构及抗冲蚀性能进行了研究。试验结果表明,等离子喷涂涂层在低角度下的冲蚀明显低于高角度下的冲蚀;而耐磨修补剂（11680）涂层从冲蚀情况看,Al1O3与树脂的粘结状况是良好的,在冲蚀率上,高角度下耐剖蚀性能比低角度下好。     

Reflection Measurements Used In The Analysis Of Structural Colours Of Beetles

Reflectance measurements have been carried out on the elytral cuticle of two beetles. Great differences arise in the tiger beetle Cicindela campestris depending on the extremely structured surface and colour variation from point to point. In comparison the buprestid beetle Chrysochroa vittata appears more even. Indeed macroscopically it looks completely smooth, but there are microscopical structures complicating reflection measurements. The advantages and disadvantages of working with a macro- and a microspectrophotometer are listed. The structural properties of the colour producing multilayer system are the same in both species. Measured spectral reflectance curves show the typical form of interference colours. A second order reflectance maximum in the UV region was found. Calculations of the reflectance curves were done by the equations given by Huxley for the non-ideal type of multilayer reflectors.     

机电企业的品牌之道

纵观这些年中国工程机械行业的发展,我们发现中国工程机械市场的竞争已经开始由低水平竞争转变为高水平竞争,由产能竞争,规模竞争、转变为品质竞争,甚至品牌竞争。中国工程机械行业近十来年特别是最近五六年呈现高速、强健的发展势头。目前中国工程机械企业已经初步具备了较强的研发能力和制造能力,具有较强的经济实力和物质基础,从过去的引进、消化、吸收为主,转变到现在的集成创新、自主创新为主,并开始向原始创新迈进,正在由“内需型”向“国际型”转变,由“规模增长”向“核心能力”增长,由“产品”向“品牌”转轨。中国工程机械行业的骄人业绩打出了国威,它的成功之路给中国整个机电行业的重要启示是,企业必须守住品牌。     

分散控制系统接地系统设计中应注意的问题

电磁防护中的接地对ＤＣＳ的正常工作影响较大,本文根据现场经验介绍了应用中易忽视的问题。     

滑动轴承CAD中的数据连接技术

在CAD系统的设计中,如何处理数据的连接是一个关键的问题,本文介绍了基于ObjectARX开发的滑动轴承CAD系统中解决数据连接一种行之有效的方法,解决了CAD系统与设计所需数据间的调用连接问题,并为CAD与下一步CAPP间的数据连接也提供了一种方法。     

微波萃取-液相色谱法测定塑料产品中的苯酚

目的：建立并验证了用高效液相色谱法测定塑料产品中苯酚残留量的含量。方法：以甲醇为溶剂,采用微波萃取塑料产品中的苯酚,以高效液相色谱仪-紫外检测器进行检测,以相对保留时间定性,峰面积定量。结果：该方法回收率为98.99%～102.08%,RSD%为3.43%～5.75%,最低检出限为0.05mg/kg;结论：实验表明该方法对塑料产品中苯酚含量的测定操作简单,方便,结果准确。     

基于单片机的相位差测量系统的设计

从硬件电路和软件设计两方面介绍了一种以单片机为主控器件的相位差测量系统的设计方案,此系统可用于两个同频率的正弦信号的相位差测量,并具有硬件电路简单、测量精度高、显示直观等优点,有一定的使用价值。     

并行工程理论在汽车大型冲压零件开发中的应用与探讨

在汽车大型冲压零件开发过程中,比较了并行工程与传统串行工程的优劣,并探讨了并行工程在汽车大型冲压零件开发中的实施应用及其效益.     

MOD法在生产线平衡中的应用

主要介绍模特法（MOD法）在生产线平衡中的应用,通过对某生产线各工序的时间及操作研究,找出存在问题及有缺陷的工序,利用模特法对其分析和改善,以此证明模特法在提高生产线平衡中有显著作用,并进一步强调工业工程方法的应用在当今企业中的重要地位。     

含界面相复合材料的柔度预报

界面相对复合材料的力学行为有很大影响.考虑夹杂与界面相的联合作用,建立由夹杂、界面相、基体和有效介质组成的四相模型.首先根据有效自相容法推导出夹杂与界面相内的局部应力场,进而得到复合材料有效柔度的隐性形式,再利用Taylor级数展开得到复合材料的柔度张量的显性表达式,复合材料的柔度张量与夹杂和界面相的体积含量、夹杂形状和分布形式有关.     

基于单片机的创意彩灯控制系统的设计

介绍了一种心形的创意彩灯控制系统的设计方法,以单片机作为主控核心,与按键、显示器等较少的辅助硬件电路相结合,利用软件实现对彩灯进行控制,系统具有形式新颖、体积小、硬件少、电路结构简单及容易操作等优点。