加速度计电路组件自动测试系统研制

某型号加速度计电路组件自动测试系统可实现电路组件A测试、电路组件B测试及AB联测。本文介绍了该测试系统的测试原理、结构组成、硬件设计及软件设计。运用多功能数据采集卡的A/D功能实现了对多个电路组件进行同时测试;运用其D/A输出加分压电路完成了对电路组件A输入电压的闭环动态调节,以实现对电路组件A进行增益测试。采用VC++6.0完成了测试软件的开发。     

一种基于单片机的高精度A/D转换器设计

A/D转换器是模拟系统与数字系统接口的关键部位,一直被广泛用于通信、测控系统、等很多领域。设计一种成本低,精度高,转换速度较快的A/D转换器。采用逐次比较法,通过电压比较器,利用D/A转换器输出的模拟量与测试电压进行比较,得到最终的A/D转换结果。     

基于SoC的动态参数记录仪微型化研究

存储测试的主要特点是测试仪器置于被测对象内部或被测环境中实时地获取动态参数,为了减小测试仪器对被测对象的影响,需要减小测试仪器的体积,实现测试仪器的微型化.针对存储测试仪器的微型化需求,提出利用SoC系统集成、模块化结构等技术,将数字电路的ADC模块、控制模块、存储模块、接口模块等集成在专用SoC芯片中,同时,将测试电路分为模拟电路、SoC数字电路、电池等模块,立体封装在机械壳体里,设计并实现了微型化的动态参数记录仪.基于SoC的微型化动态参数记录仪体积约10 cm³,可以嵌入被测体内或者置入被测环境中,实时获取相关动态参数.试验表明,基于SoC的微型动态参数记录仪可以用于应变、侵彻加速度、火炮膛内压力等动态参数的测试.     

一种数字式钳形电表校验仪

本试验仪是利用A/D转换技术,将交流电流、电压信号精确的转换为直流电流、电压信号。该仪器具有显示直观、使用方便、价格便宜等特点。     

空气湿度气象动态观测校准仪设计

以同时获取标准值与被测传感器的温度、大气压力及相对湿度的动态测试数据为设计思路,设计了一款空气湿度气象动态观测校准仪,该仪器通过测量电路、信号采集电路、运算电路、显控电路及通信电路的设计,实现了连续获取标准值与被测值的温度、湿度和大气压力的实时动态监测数据的数值和时间曲线的显示功能.模拟信号-数字信号的A/D转换及电路...     

基于DLL的LabWindows/CVI仪器驱动的共享

测试系统的开发者面临着诸多的挑战,代码的可移植性和软件的可互换性是处理这些挑战的关键.在任何测试系统中,最常用的和可移植性要求最高的莫过于仪器驱动.现在VXI即插即用系统联盟和广大的仪器生产商都把LabWindows/CVI作为仪器驱动的开发平台.随着LabVIEW,Visual Basic,以及通用C/C++编程环境在测试领域的应用,如何得到适合这些编程环境的仪器驱动成为测试系统开发的一个瓶颈.本文列出了LabWindows/CVI下的仪器驱动的特征,介绍了LabWindows/CVI中动态连接库的创建、运行机制及其编程优势,详细描述了通过动态链接库实现上述几种编程环境共享LabWindows/CVI的仪器驱动的方法.这种方法充分利用了 LabWindows/CVI编程环境,减少了仪器生产商以及用户重新开发仪器驱动的时间,加快了测试系统的开发进程.     

LAN/USB在LabVIEW下的IVI编程

针对测试系统软件与系统中测试仪器不是过时,就是需要升级、更换、生命周期不匹配和减小升级测试系统花费的时间和成本问题,在介绍了IVI类驱动程序和IVI测试程序开发步骤的基础上,以通过Agilent34410A的LAN/USB为例,描述了在MAX软件中配置IVI仪器的Logical Names和Driver Sessions的过程,及在LabVIEW下利用IVI驱动设计IVI数字电压表测量程序.对正确地开发IVI应用程序、缩短开发周期和减小维护成本都具有重要的意义.     

DFT过程对A/D转换量化噪声的削弱作用

本文通过定量地分析离散傅里叶变换过程对A/D转换量化噪声统计特性的影响,得出如下结论:对于采取舍入式量化误差形式的A/D转换量化噪声,由于DFT过程的求和平均效应而受到抑制。因此,在一些专用于频谱分析的仪器中,就没有必要采用高精度的A/D转换芯片,从而可以节省生产费用。     

塑料密度测量审核的相关问题及探讨

近两年来共有72家实验室参加了塑料密度的测量审核。各实验室按照标准GB/T1033.1-2008(ISO1183.1:2004)中方法 A或ASTM D792-08的要求对我们提供的试样进行测试,其测试结果与参考值进行比对后,不符合要求的实验室为6家,占总数的8.4%。本文结合标准要求、仪器使用和人员操作等情况对测试结果不符合要求的原因进行了技术分析,为其他实验室提高塑料密度测量的准确性和可靠性提供建议。     

车载式汽车碰撞多参量测试系统的研制

本文介绍了一种自行研制的用于汽车碰撞多参量测试的32通道车载测试系统,该仪器选用12位高速A/D芯片,选用复杂可编程逻辑器件CPLD作为控制电路,缩小了系统体积,提高了系统可靠性,实现了多通道的同步、高速采集的控制,采用特殊的灌封工艺实现了高冲击条件下的大量数据的可靠存储.该测试系统已在长春一汽国家汽车质量监督检验中心进行检测试验,并成功获取了测试数据.     

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.