炭/炭复合材料的结构对磁电阻一位向曲线形状的影响

研究了四种C／C复合材料的磁电阻与测试位向的关系。其中每种试样具有不同结构的预制体，并经过2400℃～2800℃热处理。实验结果表明，这四种材料的磁电阻-测试位向曲线形状完全不同，而同一材料的曲线形状基本相同，并且与热处理测试温度和磁场强度无关。经傅里叶函数分析，材料的磁电阻-测试位向曲线形状与其预制体纤维的方向有关。     

基于PSD311的单片机智能测控系统

目的 设计一个基于PSD311的单片机智能测控系统,以及在导弹绝缘电阻测试中的应用。方法 利用PSD311的性能特点及基于PSD311的单片机智能测控系统的设计和组成。结果与结论 给出了绝缘电阻测试的原理框图,以及采用PL／M高级语言进行程序设计的流程。     

烧结工艺对铜电子浆料导电性能的影响

为了研究烧结工艺对铜电子浆料性能的影响,本文采用丝网印刷将铜浆料印刷到氧化铝陶瓷基片上,通过X射线衍射仪、扫描电子显微镜、能谱仪和四探针电导率测试仪对烧结后的试样进行了表征。结果表明:在氮气保护性气氛下,以5℃/min升温速率升到100℃,保温10min,烘干湿膜,然后以10℃/min的升温速率升到峰值温度450℃,保温20min,制得的导电铜膜层的导电性能最佳,电阻为13.45mΩ/□,满足工业化生产的要求。     

纳米铜粒子的热稳定性研究

利用惰性气体蒸发法制备了平均粒径为40～50nm的纳米铜粒子。采用示差扫描量热法(DSC)对纳米铜粒子的热性能进行了研究。纳米铜粒子在477℃开始熔化，但不同的升温速度有着不同的熔化过程。升温速率低于30℃／min时，纳米铜粒子有足够的时间长大因而观察不到明显的熔点降低。升温速率在30℃／min时，纳米铜粒子快速吸热熔化，在490℃出现明显的熔点，且绝大部分纳米粒子在此温度下熔化。     

金属电阻温度系数的扩展

在测量金属电阻温度系数的实验中,由于电阻测试系统和温度测试系统对温度的响应时间不同,升温曲线和降温曲线不重合.引导学生发现这一问题,拓展实验思路.     

基于 PSD311 的单片机智能测控系统

目的设计一个基于PSD311的单片机智能测控系统,以及在导弹绝缘电阻测试中的应用.方法利用PSD311的性能特点及基于PSD311的单片机智能测控系统的设计和组成.结果与结论给出了绝缘电阻测试的原理框图,以及采用PL/M高级语言进行程序设计的流程.     

Ti-Mo吸气材料注射成形脱脂工艺的研究

采用粉末注射成形技术制备Ti-Mo合金吸气材料。研究了脱脂工艺对坯体质量、微观结构及其元件性能的影响。讨论了化学脱脂中的溶剂、温度、时间对坯体脱脂率的影响,较优的脱脂溶剂为三氯乙烯,在脱脂温度为50℃、脱脂时间为6h条件下,脱脂率达71.55%;通过DTA/TG曲线对热脱脂工艺进行了优化,确定了热脱脂工艺参数为室温-120℃,升温速率10℃/min;120~230℃,升温速率5℃/min;230~500℃,升温速率2℃/min,保温60 min;再经过800℃烧结工艺,制备出性能优异的Ti-Mo吸气剂元件,吸气性能特征为S10=738.5 mL/s,Q120=995.6Pa·mL。     

碳纤维/硅橡胶导电复合材料的温度响应

通过升温-降温循环及升温-恒温两种方式研究了碳纤维/硅橡胶导电复合材料试样的温度响应,通过碳纤维导电复合材料的导电机理对测试结果进行了分析。该导电复合材料具有正温度系数,并具有温度弛豫现象。橡胶材料与碳纤维材料热膨胀系数的不同是造成其电阻温度响应的主要原因;而温度变化对电子能量的影响也是造成材料温度响应的原因之一。     

烧结过程对氧化锌压敏陶瓷晶核形成和生长过程的影响

粞文研究了烧结过程中升温速度及其温区对Ａ，Ｂ两类ＺｎＯ压敏陶瓷材料的晶粒尺寸和击穿场强的影响规律，发现加快４００－９５０℃段的升温速度，Ａ类试样的晶料 寸增大，击穿场强Ｅ从６０Ｖ／ｍｍ下降到１５－３０Ｖ／ｍｍ；Ｂ类试样的闰尺寸变小，Ｅ１ｍＡ从２２０Ｖ／ｍ提高到２９０Ｖ／ｍｍ，要文从晶核形成速度和晶粒生长速度与温度关系出发，对实验结果进行了分析，讨论留念方体系决定晶核形成速度与温度的关系，在瓷料合适     

导体直流电阻测量不确定度的评定与表示

<正>一、测量依据和测量方法严格按照GB/T3048.4-2007《电线电缆电性能试验方法第4部分:导体直流电阻试验》的方法进行测量。被测对象的规格型号为BLV-450/750V 10mm2,从被试电线电缆上切取长度约为1.5m的试样,去除试样导体两端与测量系统相连接部位的覆盖物,露出导体。然后把试样放置在温度为15℃~25℃和空气湿度不大于85%RH的环境下稳定至少16h。试样在接入测试系统前清     

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.     

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 ...     

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.