δ－掺杂GaAs／AlxGa_（1－x）As二维电子气结构材料的GSMBE生长与特性

本文用ＧＳＭＢＥ技术生长纯度ＧａＡｓ和δ－掺杂ＧａＡｓ／Ａｌ_ｘＧａ_（１－ｘ）Ａｓ结构二维电子气材料并对其电学性能进行了研究。对于纯度ＧａＡｓ的ＧＳＭＢＥ生长和研究，在低掺Ｓｉ时，载流子浓度为２×１０~（１４）ｃｍ~（－３），７７Ｋ时的迁移率可达８４，０００ｃｍ~２／Ｖ．ｓ。对于用ＧＳＭＢＥ技术生长的δ－掺杂ＧａＡｓ／Ａｌ_ｘＧａ_（１－ｘ）Ａｓ二维电子气材料，在优化了材料结构和生长工艺后，得到了液氮温度和６Ｋ迁移率分别为１７３，５８３ｃｍ~２／Ｖ．５和７．６７×１０~５ｃｍ~２／Ｖ．ｓ的高质量ＧａＡｓ／Ａｌ_ｘＧａ_（１－ｘ）Ａｓ二维电子气材料。     

气态源分子束外延InGaP／GaAs结构及其在异质结双极晶体管中的应用

本文研究了ＩｎＧａＰ／ＧａＡｓ异质结构的气态源分子束外延（ＧＳＭＢＥ）生长，所得样品晶格失配率△α／α＜８．９５×１０￣（－５），本底载流子浓度为１０￣（１５）ｃｍ￣（－３）数量级，掺硅ｎ型样品的载流子浓度控制范围可达２×１０￣（１５）～４×１０￣（１８）ｃｍ￣（－３）。研究了Ｐ＿２和Ａｓ＿２气氛的切换条件对ＩｎＧａＰ／ＧａＡｓ异质结构界面特性的影响，并成功地生长了ＩｎＧａＰ／ＧａＡｓ异质结双极晶体管（ＨＢＴ）结构材料，用此材料在国内首次制成的ＨＢＴ器件ｆｒ＝２５ＧＨｚ，ｆ＿（ｍａｘ）＝４６ＧＨｚ，电流增益β＝４０，最高可达β＝１５０。     

K波段单片功率放大器

报道了Ｋ波段的ＰＨＥＭＴ ＭＭＩＣ的设计与研制。ＰＨＥＭＴ器件采用０．５μｍ栅长的３ｉｎｃｈ ＧａＡｓ标准工艺制作。三级的ＭＭＩＣ放大器在１８ＧＨｚ处,线性增益１７ｄＢ,输出功率Ｐ－１＝１９ｄＢｍ。Y     

n型GaSb,InGaAsSb的MBE生长和特性研究

本文报导了非故意掺杂ＩｎＧａＡｓＳｂ本底浓度的降低和掺Ｔｅｎ型ＧａＳｂ和ＩｎＧａＡｓＳｂ的ＭＢＥ生长与特性的研究结果。结果表明，通过生长工艺的优化，ＧａＳｂ和ＩｎＧａＡｓＳｂ的背景空穴浓度可分别降至１．１×１０~（１６）ｃｍ~（－３）和４×１０~（１６）ｃｍ~（－３），室温空穴迁移率分别为９４０ｃｍ２／ｖ．ｓ和２６０ｃｍ~２／ｖ．ｓ。用Ｔｅ作ｎ型掺杂剂，可获得载流子浓度在１０~（１６）～１０~（１８）ｃｍ~（－３）的优质ＧａＳｂ和ＩｎＧａＡｓＳｂ外延层，所研制的材料已成功地制备出Ｄ_λ~＊＝４×１０~（１０）ｃｍＨｚ~（１／２）／Ｗ的室温ＩｎＧａＡｓＳｂ红外探测器和室温脉冲ＡｌＧａＡｓＳｂ／ＩｎＧａＡｓＳｂ双异质结激光器。     

InGaAs／InAlAs多量子阱电吸收光调制器

在国内首次设计并制作了脊波导结构的Ｉｎ０．５３Ｇａ０．４７Ａｓ／Ｉｎ０．５２Ａｌ０．４８Ａｓ多量子阱电吸收型光调制器，并对它的工作特性进行了测试。在３．０Ｖ的驱动电压下实现了２０ｄＢ以上的消光比，光３ｄＢ带宽达到了３ＧＨｚ，对限制光调制器带宽的主要原因进行了分析，结果表明器件电容限制了带宽的提高，这主要是由于ＳｉＯ２刻蚀液的钻蚀导致ＳｉＯ２绝缘层厚度减小造成的。改进制作工艺可望大大改善调制器的工作     

GaAs超高速光调制器的研制

从理论与实验两方面研究了ＧａＡｓ定向耦合型行波光调制器，首次报导了重掺杂ｎ＾＋型薄层对电场分量相当于导体，对磁场分量相当于绝缘体这一发现；首次提出了一种具有对称宽电极的新型结构，并研制成功开关电压为８．５Ｖ，微波折射率为３．６，在３０ＧＨｚ情况下传输损耗小于１０ｄＢ／ｃｍ，根据ｓ参数测试３ｄＢ带宽达到３２ＧＨｚ的行波调制器。     

GaAs VCSEL／MISS混合集成光子开关

报道了ＭＢＥ生长的ＧａＡｓ材料ＶＣＳＥＬ与ＭＩＳＳ混合集成构成的光子开关。将ＭＢＥ生长的超薄ＡｌＡｓ层氧化为ＡｘＯｙ层用作ＭＩＳＳ器件的超薄半绝缘层，从而解决了该半绝缘层厚度的精密控制以及与ＶＣＳＥ工艺相容的问题。该集成器件除光子开关功能外，还能实现光放大功能，并可用于自由空间光互连。     

室温连续工作的GaAs／AlGaAs垂直腔面发射激光器列阵

报导了由选择氧化法研制的ＧａＡｓ／ＡｌＧａＡｓ垂直腔面发射激光器，ＤＢＲ中的ＡｌＡｓ经选择氧化形成的氧化层作为有源区的横向电流限制层，器件的最低阈值电流为３．８ｍＡ，输出功率大于ｌｍＷ，发散角小于７．８°，高频测量脉冲上升沿达１００ｐｓ，并由此器件制成了２×３二维列阵。     

碳掺杂GaAs的MBE生长

本文在国内首次采用自行设计的碳纤维束源炉及固态源ＭＢＥ技术生长了优质碳掺杂ＧａＡｓ、ＡｌＧａＡｓ及δ碳掺杂ＧａＡｓ外延层。获得了空穴浓度从４×１０１４ｃｍ－３到２×１０１９ｃｍ－３的ＧａＡｓ材料。用霍尔效应测量仪、电化学ＣＶ剖面仪和Ｘ射线双晶衍射仪分析了外延层的质量。用Ｎｏｍａｒｓｋｉ干涉显微镜和原子力显微镜分析了ＧａＡｓ的生长过程。结果表明碳是ＧａＡｓＩＩＶ族化合物半导体的极好的ｐ型掺杂剂。     

InAlAs／InGaAs MSM光电探测器

采用ＧＳＭＢＥ方法及典型的器件工艺制成了用ＩｎＡｌＡｓ作为肖特基势垒增强材料的高性能ＩｎＡｌＡｓ／ＩｎＧａＡｓ／ＩｎＰ ＭＳＭ光电探测器。用自制的测试系统对器件的直流和瞬态特性进行了测试，测试结果表明，器件的击穿电压大于３０Ｖ，在１０Ｖ偏压下暗电流小于２０ｎＡ，对应的暗电流密度为３ｐａ／μｍ＾２，优于已有文献的报导。     

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...     

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.……     

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.     

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.