热电偶补偿导线的校准方法

热电偶用补偿导线指在一定温度范围内(包括常温)具有与所配的热电偶的热电动势的标称值相同的一对带有绝缘层的导线,用它们连接热电偶与测量装置,以补偿它们与热电偶连接处的温度变化所产生的误差。所以热电偶补偿导线的准确性直接影响到与热电偶整体测温的准确。     

热电偶热传导测温中的动态响应时间和误差估计

热电偶是常用的测温元件.文中假设裸露热电偶的热端为一球形温度计,建立裸露热电偶热传导测量空气温度的数学模型,从理论上给出其热传导测量空气温度的动态响应时间和最大温度误差估计式,从而可知只要球形温度计在接触式测量温度时得到其动态响应时间和最大温度误差即可满足所求公式.在实际中,应用裸露热电偶温度传感器测试装药中孔隙内气体爆炸时的温度,可以满足测试要求,说明理论上提出的公式是正确的.     

共极三电偶探针测温特性分析与研究

为解决航空发动机恶劣工况下,贵金属电偶在低温测量段热电势较小、灵敏度较低、价格昂贵,多种热电偶结构复杂,且布设到空间同一位置难度较大的问题,基于热电偶测温原理,提出共极多偶的测温方法。设计加工6种不同的共极三电偶组合试验件,采用双极比较法进行静态测试试验,结果表明各测量回路热电特性在相应的温度范围内均具有良好线性度和重复性,并达到Ⅰ级热电偶的精度标准。利用激光法测量共极三电偶的热响应时间常数,测试结果达到航空发动机温度稳态测试指标,具备工程应用价值。     

超声测温技术在模拟航空发动机燃烧室温度测量中的应用

温度的测试对航空发动机的发展具有重要的意义,燃烧室出口温度是航空发动机的一个重要参数.超声测温技术具有测温范围广、响应快、精度高等优点,近年来被广泛应用于高温测量领域.设计了一套应用于模拟航空发动机燃烧室的超声测温系统.介绍了超声测温的基本原理,设计了基于铱铑合金的超声测温传感器,并在1 600℃高温炉内进行温度与声速的标定实验,最后将铱铑合金超声测温系统应用于模拟航空发动机燃烧室出口气流温度的测量试验中,获得温度-时间曲线,同时将测量结果与热电偶测量数据进行对比分析.结果表明,铱铑超声温度传感器的测量准确度可以达到97%.     

燃气稳态温度测量及误差分析

该文旨在研究燃气流稳态温度的测量技术,搭建模拟航空发动机燃烧室出口温度测量实验台。根据燃气温度测量实验台测试段的结构特点,选取横向总温热电偶作为总温传感器。采用总温热电偶对实验台测试段燃气流的稳态温度进行测量,并对得到的总温热电偶测量端燃气温度数据进行导热、速度、辐射和动态响应等方面的误差分析,且提出相应的减小误差的措施,将各个误差控制在合理范围之内。     

航空发动机热电偶冷端温度检测电路设计

航空发动机涡轮后燃气温度是发动机重要的性能参数,涡轮后燃气温度通过镍铬-镍铝元件组成的热电偶来测量。本文分析推导了热电偶测温公式,阐述了热电偶测温原理,在此基础上设计冷端温度检测电路,经应用于某型航空发动机检测系统证明,效果非常理想,很好地满足了实际工程需要。     

红外测温系统在航空发动机轮盘试验中的应用

该文论述了红外测温基本理论和红外测温仪工作原理,设计开发了适用于航空发动机轮盘试验的非接触红外测温系统,分析影响红外测温系统测量准确度的主要因素,研究发射率的确定方法,在轮盘静止和旋转状态下进行了试验验证。其结果表明:影响红外测温系统测量准确度最重要的因素是发射率;用热电偶对发射率进行确定的方法是可行的;轮盘在静止和旋转状态下的发射率相同,静止状态下确定的发射率可用于旋转状态下的温度测量。     

基于双热电偶的瞬态流体温度测试方法研究

针对目前航空发动机空气系统瞬态温度测试频响的需求,提出一种基于双热电偶的瞬态流体温度测试方法。该方法利用两个结点大小相同但材料不同的热电偶测量流体同一空间点的温度,并基于集总参数法反推出流体真实温度,并给出考虑误差的后处理算法。基于固体导热数值计算,验证此方法的可行性及相关后处理方法的可用性。采用双热电偶装置,对管道流动温度变化进行测量,基于微细热电偶的测量结果标定两支热电偶的物性参数比,应用后处理程序实现流体温度的反推。试验结果表明:标定段的反推流体温度平均测量误差率为0.52%,校验段的反推流体温度平均测量误差率为1.6%,反推流体温度的响应速度与微细热电偶响应速度相当。     

带补偿导线热电偶测温时的误差分析和修正方法

文章根据带补偿导线热电偶的测温原理,对测量误差进行了分析,给出了配用补偿导线热电偶的测温误差修正方法。     

谈热电偶的温度计量误差

热电偶是一种常用的温度传感器,应用相当广泛。在长期工作过程中,热电偶性能会发生改变,产生测温误差。我国计量法规定,在热电偶的使用过程中需要进行周期性的检定和修正,以确保热电偶温度计量的准确性。本文针对热电偶的工作原理,产生误差的原因及相应的解决办法做了阐述。为正确选择与使用热电偶,保证其测量准确性提供了一定的技术参考。     

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