圆主形声学共鸣腔端面平行性测量

圆柱形声学共鸣腔特征长度是声学共鸣法定义玻尔兹曼常数中一个关键参数,圆柱形声学共鸣腔的端面平行性是确定圆柱形声学共鸣腔特征长度的重要因素.采用Fabry - Perot腔激光等倾干涉原理,通过旋转圆柱形声学共鸣腔,实现了圆柱形声学共鸣腔端面平行性的高精度测量.     

探测激光超声信号的Fabry—Perot干涉仪及测试系统的研制

本文自行研制了一台Fabry—Perot干涉仪及其用于探测超声信号的测试系统。利用该系统对非光学表面的铝板和铜板实现了nm级窄脉冲激光超声信号的非接触式检测,其信噪比足以满足进一步信号处理要求。     

调制式光纤甲烷气体传感器的研究

利用Fabry-Perot腔的选频特性，考虑与光纤的低损耗窗口相一致和价格等因素，以价廉的1300nm波段的LED作为光源，实现了PZT对Fabry-Perot腔的正弦调制；对甲烷气体浓度进行谐波检测，检测灵敏度可达10ppm。研究表明，该传感器灵敏度和稳定性大大提高。     

用激光干涉原理调校三面直角反射镜的三个互成90°的二面角

本文叙述用激光干涉原理调校三面直角反射镜的三个互成90°的二面角。基本原理:用一块镀有半透膜的标准平面反射镜与三面直角反射镜组成等效Fabry——Perot(法布里——珀罗,文中简称F—P)干涉仪,借助激光干涉原理进行调整和校验。经实践,本方法不需贵重仪器设备,精度较高,装置简单,操作方便。精度主要依赖于所选用的标准平面镜的平面度。     

利用光学方法测量实验室标准传声器的前腔深度

实验室标准传声器的前腔深度是耦合腔互易法校准其声压灵敏度的主要不确定度分量之一.为了控制声压灵敏度校准的不确定度,利用光学三坐标自动测量系统,分别通过直测法和块规法测量3只LS1P和3只LS2P传声器的前腔深度.测量结果表明,在传声器外环面放置高精度的块规,较好匹配了传声器与平面波耦合腔进行声学耦合时的物理模型,其前腔深度测量不确定度优于3.0 μm(k=2).对于LS1P传声器20 Hz～10 kHz频率范围内的声压灵敏度,前腔深度引入的不确定度分量优于0.005 dB(k=2);对于LS2P传声器,20 Hz～25 kHz频率范围内的不确定度分量优于0.012 dB(k=2),能够实现实验室标准传声器声压灵敏度的高精度校准.     

F⁃P干涉仪差分锁频系统研究

为解决法布里?珀罗（Fabry?Perot, F?P）干涉仪锁频方法响应速度、抗干扰能力、长期稳定性方面存在不足的问题,提出了F?P干涉仪差分锁频方案,将存在频差的双频激光耦合入F?P谐振腔,当激光频差足够小时,两光强信号曲线存在交叉,以两光强信号的差值作为被控量,在交叉点附近构建单调过零函数,作为闭环控制系统的反馈量,实现动态差分锁频控制。基于该方案,搭建了一套F?P干涉仪微位移测量装置并开展实验验证,结果表明该装置能够实现0 ~ 300 nm范围内的微位移测量,位移测量分辨力达到23 pm,验证了F?P干涉仪差分锁频方案的有效性,为推动微位移测量领域的发展提供了重要借鉴。     

基于连续波激光器衰荡腔吸收光谱的痕量气体探测方法

本文描述了一种采用连续波激光激发衰荡腔光谱测量痕量气体浓度的实验装置。CRDS是基于比尔定律的吸收光谱技术,通过将光耦合到含有样品的高精细度光学谐振腔并测量光衰减速率来测量样品浓度的。它提供了绝对的和高精度的分子浓度的测量方法。这种技术只需要激光二极管提供单一模式的适度的激光功率,使系统易于运输。近红外区域,很容易与周围环境温度二极管访问包含了泛频振动能级和禁止的许多重要物体的电子跃迁。我们的研究重点是研究连续波激光激发衰荡腔光谱的性质,以增加这些物体的检测灵敏度。具体来说,我们正在研究在范围从ppb到ppt范围湿度测量。最近,我们获得了比吸收谱测量方法更好的检测极限灵敏度1x10-11cm-1Hz-1/2。我们将讨论该设备及其应用,目前的表现数据。     

银掺杂的半导体氧化物二氧化碳传感器研究

报道了银掺杂的半导体氧化物CuO-BaTiO_3对CO_2的敏感特性。分析了Ag掺杂量对CuO-BaTiO_3灵敏度的影响。Ag掺杂量不仅影响CuO-BaTiO_3对CO_2是的灵敏度和工作温度,还影响材料在空气中的电阻值。通过适当量的Ag掺杂提高了CuO-BaTiO_3的化学活性,增强了对CO_2的吸附和反应,使传感器对CO_2的灵敏度提高。银掺杂的CuO-BaTiO_3传感器对CO_2的检测范围为1.0×10~(-4)到10％,最小检测浓度为1.0×10~(-4)。还对银掺杂后的稳定性进行了分析。     

实验室标准传声器前腔体积的测量方法研究

实验室标准传声器的前腔体积(包括等效体积)是耦合腔互易校准声压灵敏度的主要不确定度分量.为了控制前腔体积与等效体积引入的不确定度分量,应用声学方法测量实验室标准传声器的前腔体积,分别利用有源耦合腔结合系列哑头空腔的方法和多个平面波耦合腔的方法对LS1P和LS2P传声器的前腔体积与等效体积之和进行测量.实验结果表明,有源耦合腔法和多个平面波耦合腔法均能有效测量实验室标准传声器的前腔体积,且测量结果具有较好的一致性.前腔体积的精确测量实现了实验室标准传声器声压灵敏度的高精度校准.     

干涉型光纤传感局放超声检测灵敏度影响研究

针对电力设备局部放电检测灵敏度要求较高的问题,提出不同长度的延迟光纤对基于干涉型Sagnac光纤传感技术的局部放电超声检测系统灵敏度的影响,设计电力设备局部放电模拟装置,搭建干涉型Sagnac光纤法检测局部放电系统,进行局部放电光纤法检测灵敏度理论分析与试验验证。试验证明,在10 kV电压等级下,传感光纤长度在10 km以内,当延迟光纤的长度约为12～18 km时,局部放电频域信号中心频率强度有最大值;当延迟光纤长度为12.353 km时,传感光纤对局部放电时域信号响应的灵敏度较高。研究表明,调节合适的延迟光纤长度,可以提高干涉型Sagnac光纤法检测局部放电时域和频域信号的灵敏度,可为电力设备局部放电光纤法检测灵敏度的提升提供新的思路。     

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.