碳／碳复合材料高温多热物性参数测量系统

提出一种将多光谱辐射测温技术、激光狭缝扫描检测技术和对试样通电加热至稳态技术相结合的新方法,可对碳/碳复合材料在高温下的多个热物性参数进行测试.利用大电流快速将棒状碳/碳复合材料加热至稳态.通过辐射高温计对试样表面温度分布的测量和激光狭缝扫描检测仪对膨胀量的测量,根据流过试样的电流、电压就可计算出被测试样的电阻率、热膨胀系数、导热系数、比热、全波长半球向全发射率和多个光谱下的法向光谱发射率.该装置主要包括高温环境实验箱,加热供电回路、高速光学高温计、激光狭缝扫描检测仪等部件,介绍了各组成部分及其工作原理.激光狭缝扫描检测仪的最大测量误差小于±3um,两套温度计的测量精度都优于1%.     

均匀活塞阵辐射声场研究

主要研究了均匀活塞阵的近-远场的辐射声场。首先利用点源声波干涉原理建立均匀点源活塞阵的辐射声场理论,进而推导均匀活塞阵的近-远场的辐射声场函数表达式,并采用Matlab软件仿真了近-远场的辐射声场,分析了近-远场的声场变化规律、声轴方向声压的变化规律和旁瓣级的变化规律。通过与实测的80 kHz均匀活塞阵换能器近-远场的辐射声场对比,表明了实测结果与仿真结果基本一致,验证了理论与测量方法的可行性,能够为实际测量工作提供指导。     

腹板参数对槽形梁结构噪声影响分析

为分析腹板参数对槽形梁结构噪声的影响,基于车辆-轨道耦合动力学理论,建立轨道交通槽形梁的有限元模型和边界元模型,采用有限元法和间接边界元法计算分析列车荷载作用下的槽形梁结构噪声特性,最后又分析腹板厚度和腹板半径对槽形梁结构噪声的影响。分析结果表明:轨道交通槽形梁结构噪声的峰值频率在31.5 Hz至80 Hz之间;增加腹板厚度会增大近场点的最大线性声压级,但对远场点的噪声具有一定的降噪作用;增大腹板半径对近场点的结构噪声影响较小,但却会增大远场点的结构噪声。这可为轨道交通槽形梁的结构声学优化提供一定的理论参考。     

基于声学灵敏度的槽形梁结构参数影响分析

为研究槽形梁结构参数对结构噪声的影响,基于车辆-轨道耦合动力学理论,建立轨道交通槽形梁的有限元模型,并计算列车荷载作用下槽形梁结构振动响应,采用间接边界元法计算分析轨道交通槽形梁结构噪声特性。最后再利用有限差分法计算槽形梁结构-声学灵敏度,分析槽形梁底板厚度、腹板厚度和翼缘板厚度对不同声场场点的线性声压级在不同频率处的影响。研究结果表明:轨道交通槽形梁结构噪声的峰值频率在31.5 Hz~80 Hz之间。加厚底板有利于控制桥梁附近小范围内的结构噪声,对远场点的噪声无能为力;加厚腹板会增大近场点的最大声压级,但对远场点噪声具有一定的降噪作用。而且加厚底板和加厚腹板对在100 Hz以上频段场点声压的影响比较小,翼缘板厚度对槽形梁结构噪声的影响也很小。     

光栅单色仪的波长标定实验研究

采用具有线光谱的氖灯和汞灯的谱线为波长标准,研究精密双光栅单色仪的波长特性.进行了波长标定、重复性和稳定性实验,重复性为0.005 nm,稳定性为0.035 nm.给出了相同缝宽设置下波长标定的不确定度评定.实验结果表明,被标定单色仪的波长修正值与波长基本上呈线性关系,并由此确定线性拟合方程.发现单色仪波长误差与狭缝宽度设置有关,对精密测量有不可忽略的影响.     

一种用于场地-建筑群体系地震响应分析的二维耦合法

该文章发展了一种用于计算场地-建筑群体系地震响应的二维耦合法，其中采用间接边界元法模拟远场土体，采用有限元法模拟近场土体，用解析算法的刚性基础-等效均质块体模型模拟建筑群。该耦合法的优势是建筑群无需离散单元，计算量小，结构参数简单直观，且无需人工边界即可满足场地无穷远处辐射条件。通过与已有文献结果对比，验证了该文章耦合法计算准确，精度较高。通过数值计算分析了场地-建筑群效应对结构动力响应的影响，研究表明：场地-建筑群效应可能明显放大结构地震响应幅值，这与整个场地-建筑群的特性及地震波特性有关；当建筑群中结构参数相同且结构刚度较大时，场地-建筑群效应可能对结构地震响应幅值的影响较大，尤其是处于建筑群中心位置的结构，该文章算例中放大率达36.17%;当建筑群将相同参数结构分区布置(如多层区、高层区)时，场地-建筑群效应可能对各区中心位置结构的地震响应幅值的影响较大。     

一种低交叉极化小口径超宽带天线的设计

在高精度近场法天线测量、平面波发生器应用等场合,工作频段通常受限于近场探头。为了克服开口波导探头的带宽限制,出现了基于Vivaldi天线的超宽带、小口径天线作为近场探头。然而,常见的Vivaldi天线是非对称结构,导致交叉极化性能较差。设计了一款低交叉极化小口径超宽带天线,采用5层对称结构改进了传统Vivaldi天线的非对称性,利用贝塞尔曲线设计渐变槽辐射结构、加载电阻和贴片以及刻蚀矩形斜槽,减小了交叉极化比和天线驻波,改善了天线辐射方向性图。该探头口径宽70 mm、长201 mm,在0.9～6 GHz频段内天线仿真所得交叉极化比优于40.9 dB,增益为-5.5～9.53 dBi,端口反射系数幅度低于-10 dB,其辐射方向性图在全频段不开裂、主波束指向不变。     

加肋圆柱壳水下声辐射数值分析几个问题研究

利用通用数值分析程序以及解析方法计算了单个舱段以及三个舱段单层加肋圆柱壳水下声辐射,获得了结构表面振速到远场辐射噪声的传递函数,对数值分析程序以及解析方法计算结果进行了分析比较,结果表面一个舱段结构和三个舱段结构辐射声场以及传递特性是不同的,采用一个舱段结构模型模拟多个舱段结构水下声辐射特性是不行的.采用了不同密度网格进行计算,结果表明粗网格也可以获得较好计算结果.     

模式转换型纵-扭复合超声振动加工系统的设计

将纵-扭复合超声振动在应用于切削和焊接中,能够得到较好的加工质量,并可显著提高加工效率,延长刀具寿命。基于平面简谐波传播理论,推导了螺旋沟槽处反射横波的存在性,并进一步分析了螺旋沟槽结构的振型转换原理;利用数值解析法设计了复合变幅杆,并在其锥面开设螺旋沟槽,从而成功输出纵-扭复合振动;结合有限元分析探究了螺旋沟槽角度θ、沟槽槽宽d及槽深h对扭纵振动转换比e的影响规律,从而优化螺旋沟槽参数,并拟合出变幅杆端面某质点的振动轨迹。利用加工出的实体变幅杆对有限元分析结果进行了验证。     

分光光度测量中的狭缝宽度误差及其修正

为了讨论单色仪的传输特性,本文中引入了狭缝函数 F_s(λ,λ_o)的概念。通常它可以代表单色仪通带的形状。文中还讨论了当单色仪通带为任意形状时的缝宽误差修正公式。Runge 和 Hyde 等人的修正公式均可作为特例由此公式推导出来,只不过四级以上的修正系数稍有不同而已。基于分光光度测量中要求单色仪输出光能尽量大,而缝宽误差尽量小,从理论上可证明最佳狭缝调节是使出射狭缝与入射狭缝的像等宽。文章最后部分还指出:Van den Akker 的波长校准误差并不一定是由单色仪的通带为非对称引起的。     

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