磁性回热材料低温热导率测量及Matlab数据库建模

为了建立磁性回热材料低温热物性参数数据库,准确分析深低温高频脉冲管制冷机的工作机理,以液氦温区GM制冷机为冷源,采用稳态轴向热流法测量了Er3Ni、Er0.5Pr0.5、Gd2O2S(GOS)、Ho Cu2等磁性回热材料在低温下的热导率,并利用液氦温区脉冲管制冷机对测量结果进行分析和验证。基于Matlab建模,创建了一套应用于深低温系统磁性回热材料的热物性数据库,对于深低温的获取及系统效能优化具有理论意义。     

4.2—280K宽温区低温电磁驱动式热开关实验研究

为了在低温温度标定系统中实现超宽温区控温,研制了一种以电磁力驱动的主动机械式热开关,相比常规的气隙式或者材料热胀冷缩式热开关,具有工作温区宽、响应速度快等优点。以一台两级G-M低温制冷机为冷源,搭建了温度低至4.2 K的低温热开关性能试验台。通过升降温过程中的控温对比实验,测得该热开关在50 K时闭合热导为1.5 W/K,断开热导为1.2 m W/K,开关比为1 250;在240 K时闭合热导为0.4 W/K,断开热导为0.5 m W/K,开关比为80。     

空间用4 K温区预冷型JT制冷机研究进展及关键技术分析

综述了空间用4 K温区预冷型JT制冷机方案及其相关的空间项目,研究表明该类型制冷机一般由斯特林或斯特林型脉管制冷机和JT制冷机组成,前者为后者提供预冷,后者通过节流效应降温获得4 K温区的制冷量。总结了制冷机的性能参数和系统结构,对比分析了该类型制冷机与GM/JT制冷机间存在的性能差距和关键技术差别,阐明了预冷温度和压力等参数对制冷机效率的影响,指出了当前该类型制冷机的改进空间和方案。     

制冷机做冷源的低温热导率测量装置研制

设计研制了1套以4.2 K制冷机为冷源的低温热导率快速测量装置.该装置采用可拆卸的具有独立真空环境的样品测试杆,使得样品测试部件与低温冷源部件分离,从而实现不破坏制冷机冷源真空环境及制冷机不复温的情况下快速更换样品.高真空绝热恒温样品杆通过高导热柔性热桥与制冷机冷头良好热耦合.热导率测试采用稳态绝热纵向热流法.除快速测...     

中国散裂中子源低温系统的氢降温优化研究

为了保障中国散裂中子源(CSNS)低温系统的平稳、顺利降温,减小降温过程中的压力波动,避免放气造成冷源的损失和温度的反复,研究了低温系统近两年多轮降温实验的降温曲线和数据,逐渐优化了氢降温控制逻辑。通过制冷机控制软件的升级和控制逻辑的修改,实现了300—34 K的平稳降温,使降温过程由完全不可控提升到了半可控阶段。通过34 K以下降温控制逻辑的修改和优化,实现了氢循环34—16 K的平稳降温,使整个降温过程完全平稳、可控。因此,经过长达两年的氢降温优化研究,终于找到了一种可靠的超临界氢降温方法,成功实现了CSNS低温系统的平稳、顺利降温。     

GM/PT混合式制冷机二级蓄冷器的实验研究

二级脉冲管蓄冷器对GM／PT混合式制同制冷性能有较大影响。蓄冷器与脉冲管结构的布置形式对GM／PT混合式制冷机性能有着较大影响,蓄冷器体积与脉冲管体积之间存在着最佳比较,介绍了GM／PT混合式制冷机的结构和实验装置,分析了整机性能的影响因素,给出了不同结构与体积比下的实验降温曲线,并对实验结果进行了分析讨论。     

液氦温区节流制冷机流程分析及实验验证

设计研制了采用两级GM预冷的小型节流制冷机,GM制冷机在两级将氦气分别预冷至91 K和14 K.开展了开式和闭式两种形式的实验,闭式中采用带有单项阀的压缩机为循环提供高压气源.实验给出了节流降温曲线并测量了制冷量,开式和闭式实验中最低无负载温度分别为3.4K和4.27 K,4.5K时制冷量分别为30 mW和5 mW.     

液氦温区节流制冷机流程分析及实验验证（英文）

设计研制了采用两级GM预冷的小型节流制冷机,GM制冷机在两级将氦气分别预冷至91 K和14 K。开展了开式和闭式两种形式的实验,闭式中采用带有单项阀的压缩机为循环提供高压气源。实验给出了节流降温曲线并测量了制冷量,开式和闭式实验中最低无负载温度分别为3.4 K和4.27 K,4.5 K时制冷量分别为30 m W和5 m W。     

传导冷却型低温超导磁体系统的设计与实验

采用4.2 K级小型低温制冷机作为冷源,可以将低温超导磁体冷却至5 K以下,使得超导磁体处在临界温度以下,从而实现无电阻运行。采用传导冷却的形式冷却超导磁体,具有系统结构简单等优点。讲述了一套采用单台1.5 W@4.2 K的制冷机作为冷源的低温超导磁体系统,其中超导磁体由三组线圈对组成,使用Nb Ti线绕制。系统自常温开机运行,约60 h后,超导磁体降温至4K,进入超导状态,可进行加电实验。当电流加载至70 A后,中心磁场强度达到4.26 T,达到设计要求。     

单台G-M制冷机为冷源力学性能测试系统研究

以单台G-M制冷机为冷源,研究设计了一套可满足8—300 K温区内任意温度点稳定可控的材料力学测试系统,满足对材料的拉伸、压缩、弯曲等力学性能的测试要求。该系统利用少量氦气作为导冷介质,为系统内的夹具、样品等降温,降低至最低温度8 K用时14小时。选取8—300 K内多个温度点对系统进行控温测试,验证该系统在8—300 K内具有可连续稳定控温能力。利用电子万能试验机对该系统的性能进行测试,以77 K为低温的典型温度点对5a06铝合金进行拉伸测试,并与平台测试结果进行对比分析,证明该低温力学测试系统的测试结果具有较高的可信度。     

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.