轨枕筋头自动切割装置的设计

本文根据生产线的节拍要求,把实现轨枕筋头自动切割的实现方案进行论证,采用平行四杆机构在切割与生产线之间转移;采用液压顶升机构实现切割进给动作;采用仿形设计实现定位误差的弥补;通过PLC实现逻辑功能控制,以实现整个过程的自动切割,并且把取端面板组合到本工艺中完成。     

STEP 与 XML 转换系统设计与实现

通过研究现有STEP格式数据与XML文档转换实现方法,构建了一种STEP与XML格式数据之间新的转换系统模型及实现方案,给出了基于Java早联编实现SDAI,以及后期绑定实现EX-PRESS与XML Schema映射的实现方法,并设计了STEP与XML格式数据转换系统开发环境及具体实现过程,开发的针对STEP中性文件的转换程序验证了转换系统模型和实现方法的可行性。     

基于SystemView平台PCM系统仿真与分析

SystemView仿真软件可以实现多层次的通信系统仿真.本文则是利用Systemview实现脉冲编码调制(PCM)仿真,可以为硬件电路实现提供理论依据.通过仿真展示了PCM编码实现的设计思路及具体过程,对仿真后得出的波形加以分析,并设计出实际的实现电路.     

基于ARM的四足机器人分层控制系统

为了实现对具有步行、滑行复合运动的四足机器人的良好控制,实现该机器人的模块化和功能的扩展性,采用了分层控制体系架构来实现机器人的控制。使用单片机来实现舵机的实时驱动控制,使用ARM9实现传感器的采集和信息的处理．在PC机上利用VC＋＋实现图形界面的设计。     

基于CH375USB接口和MSP430单片机的数据采集设计

文章介绍一种利用CH375USB接口和MSP430计算机实现数据采集的方法,给出了具体的软硬件实现．通过此方法可以利用U盘存储数据实现远距离数据传输,迅速实现单片机和计算机的数据交换。     

基于CORDIC算法的高速高精度DDS研究与实现

针对基于查找表方法不能实现高速高精度DDS,提出了一种优化的基于CORDIC算法实现高速高精度DDS的方法.介绍了CORDIC算法实现DDS中相位到幅度转换的原理.对基于CORDIC算法的DDS实现进行了较详细的描述,并在FPGA上采用流水线优化方法实现了CORDIC算法,最后在FPGA上实现了一个高速高精度DDS,实验结果表明,设计实现的DDS能稳定高速的工作.     

一种多传感器的公交车智能系统设计

以STM32F103C8T6作为控制核心,通过HC-SR04传感器实现公交车的测距避障,红外对管传感器实现上下乘客检测,霍尔传感器实现速度测量,温湿度传感器实现车内温湿度检测,气体传感器实现车内有害气体的检测,BY-F610语音播报实现超速提示、人数上限提示和火警提示等。结合软件设计,实现公交车的智能运行并将传感器检测的数据通过LCD实时显示。     

陶瓷制品裂纹检测系统的研究

这里阐述了陶瓷制品裂纹检测的实现机理和实现方法;采用超声波传感器将裂纹信号转化为单片机能够识别的数字信号;然后通过相应功能处理程序进行处理;软件、硬件和机械机构相结合才能实现裂纹检测处理功能。该思想和实现方法为其物理实现提供了理论依据和指导。     

液压传动实验数据采集系统的软件开发

基于VB6.0的液压系统性能测试中,利用DBGrid32控件实现参数浏览,利用CrystalReport控件实现参数打印;利用MSCHART控件实现调节曲线的绘制,并通过OLE技术链接Excel对象模型实现曲线的打印功能.     

利用EDMA和DSP/BIOS实现高速数据搬移与处理

介绍基于TMS320C6713 DSP的实时频谱分析仪中高速数据搬移与处理的软硬件设计与实现方法.利用TMS320C6713 DSP提供的EMIF模块实现与不同类型的存储器进行无缝连接的功能,实现与FIFO和SDRAM等的硬件连接;不占用CPU的资源,通过EDMA控制器完成数据从外部存储器到内部存储器的搬移,实现了数据搬移与处理同时进行;同时利用DSP/BIOS实现多线程调度,实现系统的大量数据的高速搬移.     

A review of the fundamental concepts of measurement

The paper surveys the current state of the theory of the fundamental concepts of measurement which is based on the model theory of logic. A brief review is given of the historical development of measurement theory. The model-theoretic definition of measurement is presented, together with a discussion of representation and uniqueness conditions. Nominal, ordinal, extensive and interval measurement structures are outlined. The classification of scale types and the problem of meaningfulness are considered. A survey is given of conjoint and derived measurement. A brief review is made of the applications of measurement theory. Consideration is given to the treatment of uncertainty. The setting-up of systems of scales of measurement for a domain of science and its relation to theories for that domain are discussed. It is argued that measurement as defined is related to other forms of symbolic representation such as is involved in computer data representation and natural language.     

Distribution curves of sectional areas through some families of convex particles

We outline the results of a computer program which calculates frequency distributions of functions of cross-sectional regions of convex planar-faced polyhedra, ‘sphero-polyhedra’, and populations of perturbed polyhedra. This is done by ‘cutting’ a computer representation of the figure by a large number of random planes. The procedure is applied to cubes, dodecahedra, truncated octahedra, and approximate β-tetrakaidecahedra. Certain aspects of the shape of the object, e.g. sharpness of corners, angularity, compactness, and degree of symmetry are related to aspects of the shape of the distribution curves, e.g. beginning and ending points of the curves, rate of rise of the peak, relative location of the peak, and height and width of the peak.     

高速动车组减振器载荷特征研究

减振器的主要功能是提供阻尼力以衰减和抑制车辆系统振动,对高速动车组动力性能有十分重要的影响。既有研究主要将减振器处理为阻尼力以研究车辆系统动力性能,极少从动力学和结构可靠性角度关注减振器自身承受的载荷。制作某型高速动车组转向架抗蛇行减振器、轴箱减振器、二系横向和垂向减振器测力元件,在大同-西安高速线路上测试并获得该型动车组运行过程中四种减振器载荷引起的应变信号。对测试数据进行处理和分析,获得高速动车组运行工况下四种减振器载荷的时间历程,分析减振器载荷的时域和频域特征。采用雨流计数法统计减振器载荷峰谷值和频次,获得不同速度等级下载荷分布。结果表明,高速动车组抗蛇行减振器载荷最大、二系横向减振器载荷最小。轴箱减振器相对速度最大、二系横向减振器相对速度最小。减振器载荷总体上呈正态分布,而且一般有列车运行速度越高减振器载荷越大。列车正线行驶时曲线半径对轴箱减振器、二系垂向减振器以及二系横向减振器载荷影响不明显,列车速度和线路小半径曲线对抗蛇行减振器载荷影响明显。     

混合驱动机构研究进展与发展趋势

混合驱动机构是可控机构的一种,其适度柔性以及降低驱动与控制成本的特性与优势使其成为现代机构学的重要研究分支之一。随着对混合驱动机构研究的深入,混合驱动机构理论和应用也不断地发展和创新。对现有的研究成果加以分析和总结将有利于促进混合驱动机构理论和应用的进一步发展。分析混合驱动机构的内涵,分别论述双自由度和多自由度混合驱动机构的研究进展,主要包括:混合驱动机构的构型设计与可动性、混合驱动机构的轨迹特征、混合驱动机构的运动学、混合驱动机构的动力学及混合驱动机构的应用等方面的研究进展。提出混合驱动机构研究的关键问题,总结了混合驱动机构的未来发展趋势。研究成果对拓展混合驱动机构的设计空间、开辟混合驱动机构新的应用领域具有重要意义。     

机械结构液体层厚度超声谐振的测量方法

针对机械结构安全运行的需要,进行机械结构液体层厚度超声谐振测量方法研究。基于垂直入射纵波在三层介质中传播的连续模型,通过对不同厚度液体层超声反射系数分析,提出一种基于超声反射系数谐振频率的液体层厚度测量方法。在对超声谐振测量系统进行标定的基础上,进行机械结构液体层厚度超声谐振测量试验研究,同时研究了3层介质的声学特性对液体层超声反射系数及厚度测量的影响。结果表明,液体层反射系数的谐振频率能够表征其厚度。在对测量系统进行标定的基础上,测量误差基本保持在5%以内。液体层两侧介质材料的变化对液体层的测量基本没有影响,但液体层介质材料的变化将对测量系统产生影响,需要重新对测量系统进行标定。     

Evaluating the Wear in Steel-Steel and Iron-Iron Friction Pairs by the Eddy-Current Method

Results of a study of steel-steel and iron-iron friction pairs by eddy-current and X-ray methods are reported. An eddy-current transducer is shown to yield a generalized characteristic of changes in the properties of a surface layer in the process of its wearing. Similar results are obtained by the X-ray investigation of the same layer. A correlation between readings of an eddy-current device and the magnitude of the linear wear in the contact zone of tribological coupling is shown to exist at the stage of steady-state and intensive wear.__________Translated from Defektoskopiya, Vol. 41, No. 4, 2005, pp. 17–24.Original Russian Text Copyright © 2005 by Gorkunov, Kharlamov, Kogan, Zadvorkin.Dedicated to the 100th Anniversary of the Birthday of Corresponding Member of the Russian Academy of Sciences M. N. Mikheev     

纳米CeO2/Zn-4.5Al-RE复合材料的力学性能及表观粘度

测试了不同增强颗粒质量分数的纳米CeO2/Zn-4.5Al-RE复合材料的力学性能,测定了柱形试样熔化前后的高度变化率,讨论了复合材料的表观粘度,并研究了纳米CeO2含量对两者的影响规律.结果表明:CeO2的加入提高了基体的力学性能,当其含量为3%时,复合材料的维氏硬度、弹性模量和抗拉强度分别达到96.7 HV,17.1 GPa和176.5 MPa,较基体分别提高了41.2%,34.6%和34.2%,而伸长率则降低了4.6%;随着CeO2含量的增加,复合材料的高度变化率△H/H0大大降低,粘度急剧增大.     

Effect of manufacturing and assembly defects on two-stage gear systems vibration

The modeling of the dynamic behavior of a two-stage gear system is made for a general configuration of wheels location. The excitation is induced by the periodic variation of the mesh stiffness. This case describes the real working of the gearings. The variation of the mesh phasing is related to the number of teeth and also to the wheels location. We developed a plane model of a two-stage gear system. The modal analysis of the system was then treated. The calculation of the dynamic response was done by a step-by-step time integration method (Newmark algorithm). Three cases of wheels location are treated. The solutions are presented both in the frequency domain and in the time domain. Three types of geometric defects of the toothed wheels are introduced in the model: defect of eccentricity, profile error and assembly defect. An analysis of the effects of these defects on the gear system dynamic behavior is then treated.     

Development of standard reference materials for air quality measurement.

The National Bureau of Standards is engaged in a continuing program involving gaseous Standard Reference Materials for air pollution measurements. Preparation of such materials requires definition of the stability, homogeneity, and accuracy of the samples. This information is obtained by long term studies of the gas systems, by development of absolute methods of analysis, and by analysis of large numbers of samples prepared in bulk. The results of studies, extending over several years, of low concentration of carbon monoxide in nitrogen and nitric oxide in nitrogen are reported. Over one thousand samples of these materials have been analyzed and the stability with time and the within-batch homogeneity have been characterized. Accuracy is achieved by use of gravimetric standards and with dynamic dilution systems. Accuracy attainable by either method is described. The use of permeation tubes of sulfur dioxide and nitrogen dioxide is necessary in some situations because of the reactivity of the gases. Data covering the stability and accuracy of these devices has been collected over a period of several years.     

并联机器人连杆的安全行程分析

针对并联机器人存在的运动失控、铰链约束、连杆干涉等不安全因素,讨论了连杆的安全行程问题.找出了6自由度并联机器人的16种不同极限状态.通过位置反解迭代求解位置正解,并且综合考虑铰链转角约束和连杆干涉约束的方法,建立了机构的安全检验算法.然后采用二分逼近法求取连杆的安全行程.通过实例得到了机构结构参数与安全行程的关系.