1.08μmInAs/GaAs量子点激光器光学特性研究

介绍了ＩｎＡｓ／ＧａＡｓ量子点激光器的材料生长,器件制备及其光学特性的研究。器件为条宽１００μｍ,腔长１６００μｍ未镀膜激器。室温阈值电流密度为２２１Ａ／ｃｍ＾２,激射波长为１．０８μｍ,连续波工作最大光功率输出为２．７４Ｗ（双面）,外微分效率为８８％,经５０℃,１０００ｈ老化,仍有〉１．２Ｗ的光功率输出。     

高迁移率AlGaN-GaN二维电子气

用金属有机物气相外延方法在（０００１）蓝宝石衬底上生长了ＡｌｘＧａ１－ｘＮ／ＧａＮ二维电子气结构。Ａｌ０．１３Ｇａ０．８７Ｎ（７００ｎｍ）／ＧａＮ（６００ｎｍ）异质结的室温电子迁移率达１０２４ｃｍ＾２／Ｖｓ,而ＧａＮ体材料的室温电子迁移率为３９０ｃｍ＾２／Ｖｓ;该异质结的７７Ｋ电子迁移率达３５００ｃｍ＾２／Ｖｓ,而ＧａＮ体材料的电子迁移率在１８５Ｋ下达到峰值,为４９０ｃｍ＾２／Ｖｓ,７７Ｋ下下降到     

论不锈钢容器中烘烤对出气率与抽速关系的影响

为了研究真空系统中烘烤时对出气率与抽速关系的影响，在室温条件下未经烘烤和在室温条件下经过温度为１００℃和２５０℃烘烤的情况下，对出气率与抽速的关系进行了测量。测量所得出气率ｑ（Ｔｏｒｒ，ｌ／ｓ，ｃｍ＾２）遵循指数规律：ｑ＝（Ｃｓ／Ａ）＾ｍ，其中，ｃ和ｍ（０〈ｍ〈１）为常数：Ｓ／Ａ为抽气参数，其定义为抽速Ｓ（ｌ／ｓ）与真空容器表面积Ａ（ｃｍ＾２）之比，Ｓ／Ａ的变化范围从２．４６×１０＾－５到１．２６     

人组织液医学超声空化阈值的研究

本文用荧光法检测医用理疗级连续波超声作用于人组织液（血清，血浆）发生空化产生的自由基，超声阈值强度ＩＳＡＴＡ（空间平均时间平均声强）分别为０．７５Ｗ／ｃｍ＾２～０．８５Ｗ／ｃｍ＾２和０．７Ｗ／ｃｍ＾２。本研究证明荧光法是检测医学超声空化的有效方法，并提供离体人组织液超声空化安全阈值的研究结果，同时发现人血清，人血浆空化的程度工化与声强相关关系不同。     

光阴极材料GaAs／AlGaAs的组分分析

为探索砷化我阴极的光电灵敏度的影响因素,利用Ｘ射线光电子能谱、二次离子擀谱和电化学方法测试和分析了国内和国外ＧａＡｓ光阴极材料ＧａＡｓ／ＡｌＧａＡｓ的Ｃ,Ｏ含量的空穴深度分布。实验发现,国内的材料在ＧａＡｓ／ＡｌＧａＡｓ 面及ＡｌＧａＡｓ层的Ｏ含量分别为７．６％和１０．６％,Ｃ深度分别为５．２×１０＾１８ａｔｏｍｓ／ｃｍ＾３和１．０×１０＾１９ａｔｏｍｓ／ｃｍ＾３,而国外的材料的Ｏ含量相应为１．０     

用于掺铒光纤放大器泵浦源的高性能980nm InGaAs应变量子阱激光器

利用分子束外延方法研制出了高质量的ＩｎＧａＡｓ／ＡｌＧａＡｓ庆变量子阱激光器外延材料，其最低的阈值电流密度可达到１２０Ａ／ｃｍ＾２，激光波长在９８０ｎｍ左右。获得了高性能的适合于掺铒光纤放大器用的９８０ｎｍ量子阱激光器泵浦源，其典型的阈值电流为１５ｍＡ，外微分量子效率的典型值和最好值分别为０．８ｍＷ／ｍＡ和１．０ｍＷ／ｍＡ，线性输出功率大于１２０ｍＷ，在２０℃－５０℃的特征温度Ｔ０为１２５Ｋ。器件     

NH3-MBE生长极化场二维电子气材料

介绍了用ＮＨ３－ＭＢＥ技术在蓝宝石Ｃ面上外延的高质量的ＧａＮ单层膜以及ＧＮ／ＡｌＮ／ＧａＮ极化感应二维电子气材料。外延膜都是Ｎ面材料。形成的二维电子气是“倒置二维电子气”。ＧａＮ单层膜的室温电子迁移率为３００ｃｍ＾２／Ｖｓ。二维电子气材料的迁移率为６８０ｃｍ＾２／Ｖｓ（ＲＴ）和１７００ｃｍ＾２／Ｖｓ（７７Ｋ）,相应的二维电子气的面密度为３．２＊１０＾１３ｃｍ＾－２（ＲＴ）和２．６ｘ１０＾１３ｃｍ＾     

Ag—BaO纳米复合薄膜在红外超短激光脉冲作用下的内场助…

Ａｇ－ＢａＯ薄膜是一种新型光电发射薄膜材料。制备出ＩＴＯ／Ａｇ－ＢａＯ／ＡＵ三明治电极结构,在红外超短激光脉冲（ｈｖ＝１．１７ｅＶ）作用下,借助内场辅助方法,使得Ａｇ－ＢａＯ薄膜的光电发射量子效率提高了一个数量级,由钠场时的１０＾－７量级提高到内场偏压为１０Ｖ时遥２．２×１０＾－６量级;样品的阈值光强由６０ＫＷ／ｃｍ＾２降为４０ＫＷ／ｃｍ＾２,约降低了３０％。这些结果表明：内场辅助方法确实是降低Ａ     

高分子p—n异质结太阳电池的研究

用合成的十二烷基苯磺酸（ＤＢＳＡ）掺杂的聚苯胺（ＰＡｎ）导电材料和Ｂｅｉ染料组合，采用涂覆技术，研制成ＳｎＯ２／ＰＡｎ膜／Ｂｅｉ染料薄层／Ａｌ栅电极结构和Ａｌ／ＰＡｎ导电基片／Ｂｅｉ染料薄层／Ａｌ栅电极结构的ｐ－ｎ异质结太阳电池，测定了该电池的光电效应和伏安特性，在４．７２ｍＷ／ｃｍ＾２的氙灯照射下，开路电压Ｖｏｃ达４００ｍＶ短路电流Ｉｓｃ为１０μＡ，填充因子可达５７．４％，光电转换效率为０．０９     

V2O3系新型PTC热敏元件的实用研究

对Ｖ２Ｏ３系新型ＰＴＣ热敏元件进行实用性研究。结果表明，元件的性能指标达到：常温电阻率８．０×１０＾－４Ωｃｍ，升阻比３８０倍，电阻纱数６％／℃，额定电流密度１Ａ／ｍｍ＾２，响应时间０．５ｓ。该元件用作大电流过流保护元件。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

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...     

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.     

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.     

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.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

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.