基于轮轴应变的轮轨力测量方法

以高速动车车轮轮轴作为有限元建模的模型,在一定的条件下进行测量。以有限元分析作为基础通过数据分析与处理,以车辆轮轴垂向力作为离散变量分析得到其与横向力及应变的关系;再通过横向应变测算横向力和垂向力。通过基于STM32和PS081芯片的数据采集板得到应变数据,得到实际轮对轮轨接触力。     

高速并联ADC芯片采集系统设计

介绍了一种基于并联ADC芯片结构方式,实现了一种通用的、用相对较低速的ADC器件实现较高采样频率的数据采集系统的设计方法.所设计的系统以FPGA为核心器件,通过采用并联的两片AD9254模拟转换芯片作为一个数据采集通道,利用时钟芯片AD9516-3进行时钟时序分配,控制两片AD9254芯片轮询采样.实验结果验证了用两片150 MHz采样频率的ADC器件并联工作,能够使数据采集系统达到300MHz的采样频率,并能准确测试72 MHz的输入信号.     

片上系统芯片PS081在太阳能衡器的应用

为克服传统衡器精度和功耗等不足,介绍专门为衡器应用设计的片上系统芯片(system on chip,SOC)PS081的高精度和低功耗特性,以及在低功耗太阳能设计中的应用,硬件部分对上电电路和外围电路进行设计,软件部分在扫描和测量模式下实现中值滤波、延迟、LCD数字显示等部分功能。     

微小电容式传感器测量系统设计

本文研究了一种基于微分运算原理测量微小电容式传感器的电路系统,通过理论分析和实验验证了微小电容式传感器容值与系统测量所得电压有效值间的关系。系统采用文氏电桥电路作为稳定信号源,并在微分运算电路中接入待测传感器,输出信号随待测传感器应变。微分电路的输出经信号由主控芯片对其进行模数转换和运算处理,传感器测量结果可在串口打印显示,也可无线发送给外部设备,使小电容测量智能化。系统的传感器容值与输出电压有效值间转换为完全线性相关,结果易于处理,且不易受分布电容影响。此外,系统无需外接信号源,且可通过调节微分电路电阻值实现多容值范围的传感器测量。电路结构简单,易于实现,系统稳定,抗干扰性强。     

基于LPC2136的精确温度测量

针对LPC2136片内ADC的分辨率较低,不能满足测量精度的需要,而外接高分辨率的ADC成本又较高的情况,提出了采用过采样和求均值的方法增加LPC2136片内ADC的分辨率。基于过采样技术提高模数转换器ADC转换分辨率的基本原理及电路模型,给出了一个应用过采样技术增加LPC2136片内模数转换器ADC的分辨率转换结果的实现示例及其软件实现方法,并进行了温度实测实验,结果表明测量分辨率明显提高,能满足测量精度的需要。     

基于FPGA的激光外差干涉仪反正切解调技术

针对高频声学应用中多普勒信号软件解调的局限,提出了一种基于FPGA的数字硬件信号解调方案.基于AD9467设计了高速ADC采集系统,以实现原始多普勒信号的奈奎斯特采样或带通采样;基于Xilinx Zynq-7000片上芯片系统设计数字信号处理系统,实现了 DDS合成参考信号与多普勒信号混频、低通滤波产生I&Q基带信号对...     

基于ASIC芯片的微小电容测量电路研究

基于一款专用集成电路芯片（ASIC）HTl33实现了一种微小电容测量电路。该电路具有高分辨率、高抗干扰性、偏置调节能力和模拟、数字信号两种输出模式等特点。文中详细论述了测量电路的实现以及电路的抗干扰措施,并通过测定一组微小电容验证了电路的性能。实验表明,电路分辨率达0．5fF,非线性度8．67％。该电路在各种电容式传感器特别是微机电系统（MEMS）传感器中有广泛的应用前景。     

基于应变片的滚动直线导轨副负载力测量方法

针对在有限的机床空间环境下对滚动直线导轨副进行性能检测的问题,提出了一种基于应变式传感器的滚动直线导轨副负载力的测量系统方案.通过有限元仿真分析应变片最佳粘贴位置,设计小体积、低功耗的自动调零电路、信号调理电路,微处理器控制其ADC模块采集输出结果并对采集到的电压进行转换、计算,得到滑块上的加载情况.该测量系统在不影响...     

一种高精度热电偶内阻检测系统

文章介绍一种高精度热电偶内阻检测方法,采用自平衡电桥消除热电偶补偿线和外接引线及接触电阻对测量结果的影响.采用差分信号调理驱动ADC实现高精度转换,高性能单片机实现智能化检测.     

基于8255A和ADC0809压力控制系统的设计实现

基于8255A和ADC0809芯片设计实现压力控制系统,主要应用于用风门控制风道压力的情况之下。主要用到的硬件有传感器、步进电机和CPU外围接口芯片可编程外围接口芯片——8255A,A/D转换器ADC0809。系统既可以节省人力资源,又可以使这项繁琐而又难实现的工作变得简单又轻松。真正实现我们所谓的监测和控制。     

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.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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 ...