涡轮分子泵逆检流漏技术研究

一、逆流检漏方法的特点在通常的氦质谱检漏法中,被检件接在检漏仪的高真空侧,被检件通过节流阀与检漏仪的质谱室相连,如图1所示。氦气通过漏孔进入被检件并被抽入质谱室,其中一部分被主泵抽走,另一部分在氦质谱室中建立起氦分压,由此形成了     

HL-2A装置真空室总体检漏

介绍中国环流器2号A偏滤器托卡马克装置真空室总装检漏及结果.根据其真空室特点设计了不同结构的检漏子系统,用氦质谱检漏仪、四极场质谱计与氦质谱检漏仪相结合的方法(双质谱法)分别进行零部件和真空室总体检漏,对有关检漏技术问题进行了讨论.     

电真空器件的气密性检测

基于氦质谱检漏仪的结构和原理,设计了适用于电真空器件气密性检测的检漏平台。电真空器件的结构特点及测量精度要求决定了氦罩法和喷吹法是电真空器件氦质谱检漏技术中最常用方法,氦罩法测定总漏率,总漏率超出允许值后用喷吹法对漏孔准确定位。双回路复杂结构和复杂串联漏孔的定位,表明了氦质谱喷吹法在电真空器件检漏中的影响因素必须遵循的喷吹检漏原则。同时,温度、临时密封材料和设备材料吸附等因素会带来一定的测量误差。     

制冷器件检漏的两种方法浅论

本文介绍了制冷器件制造过程中检漏的两种方法,水槽检漏和真空箱式氦质谱检漏。阐述了两种方法的特点,并且介绍了两种方法的漏率计算公式。文中着重介绍了真空式氦质谱检漏的优点,以及漏率的换算关系。     

氦质谱检漏仪在溴化锂吸收式制冷技术中的应用

指出了氦质谱检漏仪在溴化锂制冷行业中应用的重要性.进一步介绍了氦质谱检漏仪的基本原理,结构,以及对溴化锂制冷机组进行氦质谱检漏时的检漏程序、检漏方法和注意事项.     

氦质谱非真空积累检漏法中几个问题的研究

氦质谱非真空积累检漏法被广泛应用于航天器的总漏率测试中,因此研究氦质谱非真空检漏法具有重要的工程实际意义。本文首次详细给出了氦质谱非真空积累检漏法计算公式的详细推导过程,同时讨论了采用柔性收集室技术可能产生的一些问题。研究结果表明:氦质谱非真空积累检漏法有着严格的理论依据;柔性收集室的技术在理论上是可行的。本文的研究结论可以为氦质谱非真空积累检漏法的工程应用提供理论依据。     

氦质谱压力真空检漏法在高压容器检测中的优化分析

本文介绍了氦质谱压力真空检漏方法在高压容器泄漏检测中的优化分析。通过给氦质谱压力真空检漏法的集气室充气工装增加辅助抽气室,避免高压条件下充气工装泄漏造成的检漏系统本底信号过高影响,提高了氦质谱压力真空检漏方法在高压容器检测中的灵敏度和检测数据的准确性,拓展了氦质谱压力真空检漏方法的适用范围。     

航天器氦质谱真空容器总漏率检测的灵敏度及可信度探讨

依据航天器氦质谱真空容器总漏率检测原理,讨论了检漏仪和真空容器直接相连、同真空容器主真空泵并联、在前级泵和主真空泵间等连接方式,逐项研究了总漏率测试的最小可检漏率、反应时间,分析各种连接方式的应用特点,认为对大型航天器氦质谱真空容器检漏系统,检漏仪连接在前级泵和主泵之间可得到较好的灵敏度和反应时间.通过测量不确定度的分析与评定,确定一般航天器氦质谱真空容器总漏率检测的相对标准不确定度小于10％.     

氦质谱背压检漏方法研究

阐述了氦质谱背压检漏的特点及目前存在的问题,在此基础上提出了改进建议。深入探讨了预充氦背压法测得的测量漏率与等效标准漏率的关系,指出预充氦背压法可用于检测压氦背压法检测不到的小漏孔,给出了等效标准漏率对测量漏率具有的双值均在分子流范围时的鉴别方法。     

氦质谱检漏仪现场校准方法研究

目前,用户采用单只标准漏孔对氦质谱检漏仪进行校准,由于受检漏仪线性范围的影响限制,不能对其全量程范围进行校准。为了满足对氦质谱检漏仪全量程范围内的现场校准,将一系列不同量级漏率的薄膜渗氦型标准漏孔分别接入氦质谱检漏仪,得到一组标准漏孔检漏仪示值,通过对标准漏孔漏率值与检漏仪示值的关系曲线进行数学拟合,得到氦质谱检漏仪全量程测量范围示值与漏率值之间的拟合公式。其校准过程简单,能够提高氦质谱检漏质量。     

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.     

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.……     

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...     

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.     

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.……     

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.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...