用于集成电路检测的复合电子透镜——能量分析器-收集器系统

研制出一种将物镜、电子能量分析器与二次电子收集器复合在一起的电子光学系统,该系统能用于集成电路的电子束检测,定量地测定微电路的电位分布。利用侧极靴磁透镜作物镜,该透镜轴上最大磁场在透镜体外,带有吸引栅的拒斥场分析器处在透镜体内,样品处有很强的透镜磁场。通过计算机优化设计,样品发出的二次电子在复合电磁场作用下大体正交地进入拒斥场分析器,确保了很高的电位分辨率。实验研究结果证实了计算机CAD设计,S曲线与理论预期的很接近。本文还提出了一种理论模型,用于分析了局部场效应,尤其是局部位垒对S曲线的影响。     

磁透镜内径比对条纹变像管性能的影响

针对一款高时空分辨率飞秒条纹变像管的带极靴磁透镜结构,提出了更加符合实际磁场分布规律的"高斯型"磁场分析模型,并且研究了磁透镜内径比对条纹变像管时间、空间分辨特性的影响。利用Lorentz软件数值研究了条纹变像管中不同内径比的磁透镜所产生的磁场分布,并且采用Monte-Carlo方法对大量光电子初始参量进行抽样计算,通过跟踪行波偏转前置短磁聚焦条纹变像管中大量光电子的运行轨迹,统计分析了光电子在最佳像面上的位置分布,最后利用调制传递函数对条纹管时空分辨能力进行评价。结果表明:当磁透镜内径比r1/r2=0.83时,磁场对电子束进行有效聚焦,获得物理时间分辨率优于190 fs,且狭缝边缘(狭缝总长度为6 mm)空间分辨率达到100 lp/mm的结果。     

铝合金强流脉冲电子束辐照熔化层尺寸数值模拟研究

强流脉冲电子束表面改性过程中熔化层尺寸是改性效果的衡量指标之一。针对改性中不同束流情况引发的温度场和融化层情况进行了仿真研究。通过对温度场变化等结果的分析,发现仅增加辐照次数不能有效增加熔化层尺寸。在总功率、辐照时间等不变的情况下可以对束斑的电流分布进行控制来实现熔化层控制。对束斑直径聚焦的仿真显示束斑尺寸对熔化层熔深熔宽均有较大影响,熔深随着束斑增大有减小趋势,熔宽则在一定束斑直径下有最大值。同时发现优化电子束电流分布是获得特定熔池尺寸的有效方法。     

考虑电子热初速分布计算磁聚焦强流电子注的新方法

电子的热初速对强流电子注磁聚焦系统的性能具有重大的影响.本文提出了一种新方法,系统地考虑电子热初速分布和空间电荷效应计算非层流强流电子注聚焦系统;导出了局部正交曲线坐标系中电流密度分布的演化方程;编写了强流电子注磁聚焦的软件,研究了热初速分布对周期磁聚焦电子注电流密度分布及其演化的影响.     

复合静电—磁浸没透镜的宽束曲轴聚焦性质及像差理论

研究了新型的复合静电－磁浸没透镜的曲光轴高斯电子光学性质及像差特性。应用宽束曲轴理论，导出了三维局部正交坐标系中的电子运动的中心轨迹方程和曲光轴的近轴轨迹方程；利用数学软件Mathematica推导出了复合静电－磁浸没透镜全部曲轴二级像差系数。作为实例，中针对轴上磁场和电场具有某种解析表达式的旋转对称的静电－磁浸没透镜系数，计算了它的曲轴高斯聚焦特性和二级像差，并给出了二级像差分布图形。     

聚焦电流和阴极位置对束流品质影响的CST仿真北大核心CSCD

电子枪的阴极位置和聚焦电流大小会影响电子束的焦距和束斑形貌,进而影响增材制造零件的质量。首先根据实际的电子枪结构,建立了1∶1三维电子枪物理模型和有限元分析模型,并采用CST软件的粒子工作室模块进行了仿真,研究了聚焦电流大小和阴极位置对电子束的焦点位置和束斑形貌的影响。仿真结果表明:聚集电流为460 mA,阴极下表面距栅极上表面为1.0 mm时,电子束在工作平面处的束斑直径为0.61 mm,电子分布较均匀且形状较圆。进行了电子束选区熔化实验,成功实现了钛合金粉末的预热和熔化成型。试验结果表明模拟仿真对电子枪的设计具有一定的指导作用,可以实现800 mm工作平面处的成功成型的要求。     

大屏幕彩色显像管电子枪电子束形成区及预聚焦透镜特点分析

束形成区及预聚焦透镜是大屏幕彩色显像管电子枪的设计重点之一。本通过计算机模拟的方法对几种大屏幕彩色显像管用电子枪束形成区及预聚焦透镜的特点进行了系统分析，比较了各电子枪在不同电流下最小交叉截面位置的波动、最大电流密度的变化、主透镜中束截面形貌。分析表明束形成区和预聚焦透镜均采用四极结构的电子枪更容易实现聚焦稳定性和附加理想的像散。     

电磁微电机中平面微线圈磁场分布特性的研究

本文分析了电磁微电机中平面微线圈产生的空间磁场，把微线圈等效几何圆电流和矩形截面电流，导出了空间磁场的计算公式，接着通过四种算法的比较，建立了平面微线圈空间磁场快速准确的数值算法，最后分析了平面微线圈空间磁场的分布特性。     

复合静电-磁浸没透镜的宽束曲轴聚焦性质及像差理论

研究了新型的复合静电 磁浸没透镜的曲光轴高斯电子光学性质及像差特性。应用宽束曲轴理论 ,导出了三维局部正交坐标系中的电子运动的中心轨迹方程和曲光轴的近轴轨迹方程 ;利用数学软件Mathematica推导出了复合静电 磁浸没透镜全部曲轴二级像差系数。作为实例 ,文中针对轴上磁场和电场具有某种解析表达式的旋转对称的静电 磁浸没透镜系数 ,计算了它的曲轴高斯聚焦特性和二级像差 ,并给出了二级像差分布图形     

电子束快速成型机聚焦及偏扫系统的工程实现

阐述了电子束快速成型机聚焦及偏扫系统在工程上所遇到的几个问题及解决方法。主要有:制造工艺引起s、t轴偏扫不垂直,通过斜角坐标和直角坐标数据互换算来解决此问题;电子束偏转后束斑散焦,采用以电子束偏转位置为因变量校正聚焦励磁电流来解决此问题;电子束聚焦校正励磁电流与反映位置的s、t轴偏扫励磁电流之间存在非线性,采用偏扫场按扇形分区,试验获取特征点参数数据,区域内每点参数按线性近似处理;磁路动态损耗影响聚焦补偿精度和偏扫精度,励磁电源指令电压采用比例-微分输入方式加以解决。试验结果表明电子束斑的均匀性和偏扫精度均明显优于无补偿系统。     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.