低温循环对标准铂钴电阻温度计稳定性影响的实验研究

低温,尤其是低于24.5561 K(氖三相点)温区,常用的三种标准电阻温度计是铂、铑铁和铂钴电阻温度计.铂钴电阻温度计在20 K以下的灵敏度和稳定性与铑铁电阻温度计相近,可作为精密测温的标准器使用,越来越受到低温界的重视.本文研究了自研的铂金壳标准铂钴电阻温度计低温温循后的短期稳定性,介绍了标准铂钴电阻温度计低温温循考...     

低温铂钴电阻温度计

一、前言在铂、铑等贵金属中掺入微量铁、钻之类的磁性元素时,便可制得用作极低温测温元件的稀合金。在极低温条件下,这些合金的电阻,温度之间的关系——R·T特性与纯金属的略有不同。这种现象称为近藤效应(Kondo effect)。英国国立物理实验室(NPL.)研制成铑铁电阻温度计。日本计量研究所则研制成了铂钴电阻温度计。由于能够有效地利用历史悠久的铂电阻温度计所积累下来的制造技术和测量技术,所以     

ITS—90温标在83.8058—273.16K温区内温标的非唯一性研究

对ＩＴＳ＿９０温标在８３．８０５８－２７３．１６Ｋ温区内的温标的非唯一性进行了研究。在高精度低温恒温槽内对九支套管铂电阻温度计进行分度,分析其非唯一性,并研究此温区与１３．１８－２７３．１６Ｋ温区的非一致性。     

电阻比W100=1.385铂丝的研制

一、前言利用铂丝的电阻为温度的确定函数,将它制成温度计来测量温度已有好几十年的历史。从1927年起标准铂电阻温度计就被确定作为温标内插标准器(当时定为—196～660℃范围)。经过半个世纪的研究和发展,铂丝的纯度和铂电阳温度计的性能都有了很大提高。 1968年国际实用温标(IPTS-68)规定标准铂电阻温度计用来作为13.81K(氢三相点)到630.74℃(锑凝固点)的内插标准器,并被考虑作为延伸到1064.43℃(金凝固点)的内插标准器。 1960年以后,工业铂电阻温度计的温度上限提高到850℃,其电阻温度系数α=0.00385/K,即W_(100)=(R_(100))/(R_0)的名义值为1.385。这种铂电阻温度计的优点是稳定性好,适用范围     

标准铂电阻温度计使用技巧分析

标准铂电阻温度计是传递-189．3442℃～660．323℃温度范围内国际温标的内插仪器,很多企事业单位特别是计量、热工、电力等行业中经常使用0～429．527℃温区范围的二等标准铂电阻温度计（以下简称温度计）检定工业用铂热电阻或精密测温。     

新型半导体电阻温度计

介绍一种新型半导体电阻温度计，该温度计由掺锰的ＩｎＳｂ单晶体制成。它们已被用来测量０．０１Ｋ到３５０Ｋ的温度，且显示出高的灵敏度，低电阻率和良好的重复性。这种温度计的标定校验在低温和超低温下也十分简单，因为它们是纯指数的温度－电阻关系。     

宽温区标准锗电阻温度计

为建立我国低温温标提供保存和传递温标及内插工具,研制了1～40(100)K宽温区二次标准锗电阻温度计。用于宽温区的锗电阻温度计,其电阻温度关系必须呈现“软”过渡特性,并能用一个合适的数学分析式以足够的精度拟合电阻—温度关系;同时,作为二次标准温度计使用,必须具备高的复现性。本文着重给出了上述方面的初步研制结果。     

发电机组中的电阻温度计

分析了我国大型发电机组中使用测温电阻的现状。提出了新的产品设计来改变现用电阻温度计的结构,用铂电阻取代铜电阻,用膜式电阻元件取代线绕电阻元件,认为这些可行措施是提高发电机组中的电阻温度计测控精度及可靠性的主要途径。     

ITS-1990国际温标分度工业铂电阻温度计的实验研究

长期以来工业铂热电阻均采用Callendar-Van Dusen (CVD)方程的方法来分度,标准铂电阻温度计是根据国际温标ITS-1990采用不同温区的内插公式来分度.在CVD方程和ITS-90温标的内插公式之间存在系统差异.实验研究及结果表明,将ITS-1990国际温标内差公式的方法用于工业铂电阻温度计是可行的,在...     

一种新型的铂电阻非线性校正方案

本文采用引线电阻影响消除技术实现了铂热电阻输出信号的高精度线性放大，将模－数转换器与可编程只读存储器结合使用，提出了硬件查表线化方法，从而实现了铂电阻温度计的高精度线性化。实验结果表明以上技术方案切实可行，开避了线性化方法的新途径。     

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