ADS 2K低温系统超流氦换热特性研究

以ADS 2K低温系统为研究平台,分析了恒温器结构参数中上升管与峰值热量的关系,测量了超导腔液氦池中不同工作温度下的超流氦峰值热量,最后给出了恒温器上升管的设计方法,并验证了ADS低温恒温器上升管设计的合理性。     

Spoke型超导腔水平测试低温恒温器的设计

Spoke型射频超导(SRF)加速腔水平测试低温恒温器是中国科学院先导专项加速器驱动次临界系统(ADS)项目的重要设备之一,水平测试成功与否,直接影响到超导腔、耦合器、调谐器等能否带束流运行。对水平测试恒温器的功能及工作流程进行了初步分析,通过对恒温器中部分关键部件结构及热力学分析,以及不同温区热负荷模拟分析研究,确定恒温器的结构形式,同时为恒温器的低温测试和运行的稳定性提供理论依据。     

深圳产业光源低温系统的概念设计（英文）

为促进同步辐射光源技术在粤港澳大湾区的发展,深圳市以“产业光源”为定位目标,计划建设一台高性能的中能同步辐射光源。为满足深圳产业光源未来3台超导腔的测试与在线运行需求,需建设一套制冷量达到2 000 W@4.5 K的液氦低温系统。首先简要介绍了低温系统的热负荷估算和系统布局,然后介绍了低温系统的技术指标、2 K获得方案、系统原理及工作流程,最后着重阐述了关键设备垂直测试杜瓦和水平测试恒温器的设计方案。     

北京正负电子对撞机重大改造工程超导腔恒温器静态热负荷分析

北京正负电子对撞机重大改造工程(BEPCII)采用了频率为500 MHz的单cell超导纯铌腔作为加速腔.通过有限元分析的方法对超导腔恒温器各部件进行热模拟和分析,并将模拟分析结果与超导腔的水平测试结果进行比较验证,确认数值分析结果为可信的,且得出对备用超导腔恒温器设计、加工和运行具有指导意义的结果.     

2K以上超导转变温度标准的测量装置

本文描述了利用互感法测量超导转变温度的原理、测量装置和测量方法。测量装置包括:低温恒温器、两种超导材料(铅和铟)的超导器件、简单的互感电桥线路及测量系统。测量结果的重复性小于±1mK,综合不确定度为±3mK(置信度为99%)。从而建立了2K以上超导转变温度测量装置。     

中小型超导磁体用低温恒温器的安全

从工作压力角度分析了中小型超导体磁作用低温恒温器的安全问题，并给出了超导磁体猝灭引起低温恒温器压力变化的实验观察实例，以及超导Ｗｉｇｇｌｅｒ磁体低温恒温器的安全设计。     

实验用低温恒温器及相关制冷技术研究进展北大核心CSCD

低温恒温器通过制冷技术提供稳定的低温环境,广泛应用于磁共振系统、超导、低温光谱、大型科学装置以及实验室低温测试等领域。目前获得低温的方式主要有制冷剂和低温制冷机,受限于被动式制冷机的制冷量,现有实验用低温恒温器仍以制冷剂和主动式制冷机为主。文章介绍了常见的实验用低温恒温器结构及其发展与问题,并分析了市场上主流产品的解决方案。同时,介绍了国内低温恒温器技术的发展,包括一款自研的低温薄膜电阻测试仪,最后简要地展望了低温恒温器的发展前景。本研究为国内同行提供技术参考。     

超导稳频振荡器的研究

基于理论分析和计算机仿真,得到了超导稳频振荡器的设计方案,主要包括高Q超导腔、低温环境及锁相环电路等组件的设计。通过实验验证,超导腔的Q值达到2×10⁹,低温环境温度达到1.8 K,温度的稳定度优于0.001K。根据实验结果优化设计后进行系统联调,得到了初步实验结果,超导稳频振荡器的1s频率稳定度达到10^-13量级     

超导转变温度测量中所用的液氦蒸汽压调节器

一、引言在我们研制的超导转变测量装置需要测量氦沸点(4.2K)以下温度的超导转变时,采用了对恒温器内小液池里的液氦进行抽空减压降温的方法,这种方法可使低温液体的温度控制在正常沸点至三相点之问。我们用它作为测量2K以上超导转变温度的冷浴的方法。不过,单纯用此方法,会发现:被减压液池内,随着减压泵速率和环境温度等的变化液氦温度将大幅度波动。为此,通常采用对液池内加热或用固体导热平衡等方法控制液池内液氦的蒸发     

实验室用氦低温恒温器

KГ～15／150、KГ-60／300金属低温恒温器，容量为15、60升；非金属低温恒温器，容量为70升，其用途是将仪器和没备冷到液氮温度。     

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.     

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.     

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.……     

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.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to