低温下固体材料导热系数的测定

研制了一套能在４～３００Ｋ温区和１×１０￣（－４）～１×１０￣２Ｗ．ｃｍ￣（－１）·Ｋ￣（－１）导热系数范围内，测出各种固体材料导热系数的装置。本文介绍了装置的原理、结构、几种工程材料导热系数的测试结果。该装置具有结构简单、操作方便等优点。     

导热高分子材料研究进展

讨论了提高聚合物导热性能的途径－合成高导热系数的结构聚合物，用高导热无机填料对聚合物进行填充复合。综述了导热高分子材料的研究成果：聚合物导热的基本概念和影响其导热性能的因素及导热系数的预测理论；聚合物基导热复合材料的选材、复合技术及其应用。指出了导热高分子材料的研究方向－－纳米导热填料的研究和开发；聚合物树脂基体的物理化学改性；聚合物基体与导热填料复合新技术的研究和开发；复合材料导热模型的建立、导热机理（特别是聚合物基体与导热填料界面的结构与性能对材料导热性能的影响）及导热通路的形成等；探索高导热本体聚合物材料的制备方法和途径等。对导热高分子材料的研究和开发有重要意义。     

以物体瞬态温度值测算物体导热系数的原理与方法

提出了一种有别于现有各种测定物体导热系数k的方法。其原理是将物体瞬态温度场解析解与测量物体内某处温度值相结合来测算k。文中简述了测算步骤,并提出实验环境、条件安排和测量参数值范围的优化原则与判据。对测算误差及影响因素做了分析,并对测算结果进行了初步实验验证,结果表明,本文测算值与由其它方法所得到的数值相比较,相对偏差为0.8%～4%。     

测定保温材料导热系数的自补偿圆管法的方法误差分析

本文对测定保温材料导热系数的自补偿圆管法的方法误差进行了分析。在００４～０１０Ｗ／（ｍ·Ｋ）导热系数范围内，固定功率补偿子方案的方法误差不超过２３％；而在００４～００６和００６～０１０Ｗ／（ｍ·Ｋ）分区域范围内则分别不超过１３％和１０％。这表明，测定保温材料导热系数的自补偿圆管法采用固定补偿因子方案在原理上是可行的。     

泡沫混凝土导热系数模型研究

研制了系列不同容重的泡沫混凝土,对泡沫混凝土的气孔率和导热系数进行了测试.在此基础上利用二相体系材料导热系数模型对实验结果进行了分析,运用Matlab软件进行了拟合;改进了Maxwell方程,提出并验证了适用于泡沫混凝土的新方程.经测算,理论预测值与实验结果显示了良好的一致性,研究结果表明,所提出的导热系数新方程适合于指导设计特定配比的泡沫混凝土.     

稳态法测算导热系数的原理

分析了测量导热系数传统模型与相关文献中的修正模型的原理与不足,提出一个较为严密的三维传热学模型,利用MATLAB数值模拟验证了其合理性。推导出计算圆柱型试样导热系数的公式,并得到了适合实际应用的简化公式。以真空橡皮盘为例,定量分析了侧壁散热对导热系数测量值的影响程度,给出了试样规格与测算精度的关系曲线。当试样半径与厚度的比值大于28.9时,侧壁散热的影响将小于5%,故可忽略。     

利用瞬态热线法测量固体导热系数

在利用瞬态热丝法测量固体与流体导热系数方法研究的基础上,对固体的导热系数进行了计算,提出了既有理论意义又包含了测量参数、既严格又简便的新表达式;分析与定量计算了模型误差、截断误差、热阻误差、热容忽视误差及测量系统的合成误差;并指出了减小误差的措施。在实验研究中,建立了试件测试台和自动化参数采集与数据处理的计算机测控系统。测量结果表明,所测得的3种固体材料的导热系数值与文献参照值相差约5％。具有一定的实用价值。     

纳米碳管强化水合物导热的研究

实验研究了不同温度（258．15K～270．15K）、不同纳米碳管含量（0．1wt％～10wt％）以及有无分散剂十二烷基硫酸钠（Sodium Dodecyl Sulfate,SDS）情况下四氢呋喃（Tetrahydrafuran,THF）水合物的导热系数。结果表明：THF水合物的导热系数随纳米碳管含量的增加而显著增加,纳米碳管的加入并没有改变THF水合物导热系数随温度的玻璃体变化特性。在纳米碳管质量分数一定时,随着温度的升高,THF水合物导热系数增大的速率越来越快。对于含纳米碳管的THF水合物,不加分散剂时的导热系数比加分散剂的导热系数低,但高于纯THF水合物的导热系数。     

霜层综合导热系数的研究

提出了霜层综合导热系数概念。认为霜层导热系数除了应考虑霜层结构复杂性还应计及蒸汽凝华潜热释放的影响。从霜层能量平衡分析出发，导出霜层综合导热系数是霜层有效导热系数和蒸汽有效导热系数之和。据此计算的霜层综合导热系数与实验数据符合较好。     

AlN/EP导热绝缘灌封材料的制备及性能研究

以微米级A1N为导热填料，与环氧树脂共混制备了导热绝缘胶，并研究了AIN的含量对AIN／EP复合材料导热系数和介电常数的影响。当AIN的质量分数从0％增加到56％时，AIN／EP复合材料的导热系数从0．188W／（m·K）增大到0．869W／（m·K），是纯环氧树脂的4倍多；介电常数也从3．56增大到8．51，满足绝缘...     

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