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.     

On the analysis of in-tube flaw-detection results characterizing the state of a trunk gas pipeline with corrosion flaws

Today, results of in-tube flaw detection (ITFD) are used mainly to solve routine problems of the provision of service reliability of operating gas pipelines (via the removal or selective repair of damaged pipes). However, the task of nondestructive testing consists in not only the detection of flaws but also in the determination of the principal causes of their appearance. This calls for the use of quantitative indexes of flaw parameters for estimating steady tendencies toward the development of damaging, determining the most essential causes of the formation of detected flaws, and predicting possible dynamics of their propagation as the time of operation of a trunk gas pipeline (TGP) system increases. These tasks can be solved based on an analysis of primary results of ITFD by selecting and using steady quantitative indexes of the total damaging using statistical techniques.Translated from Defektoskopiya, Vol. 40, No. 10, 2004, pp. 79–88.Original Russian Text Copyright © 2004 by Gorchakov, Dolgov, Yu. Surkov, Rybalko, A. Surkov.     

动压气体润滑在精密仪器上的研究发展

本文综述了动压气体润滑在精密仪器上的研究发展情况。动压气体润滑在精密仪器上研究应用在气体润滑的研究领域中开展得最早,五十年代已在惯性导航用陀螺仪表上应用了动压气体润滑,从而对美国第一颗人造卫星的成功发挥了作用。这些年来在其它精密仪器上的应用取得了不少成效。例如:在大型电子计算机用的磁鼓、磁头和激光打印机上都有成效。本文就动压气体润滑的特点、动压气体轴承的设计、材料、加工方法等方面以及动压气体螺旋槽式轴承的实例进行了综述。     

基于单姣运动链的周转轮系列创新综合方法

将单铰运动链用于周转轮系的创新综合，提出了创新综合的结构学原理与方法，不仅得到了常用的基本周转轮系及各种复合轮系，而且还得到了一些用传统组合方法难以获得的新型周转轮系，从而为周转轮系的创新设计提供了一种新的途径，同时也为由型数综合理论理论的一些多杆单铰运动锭的实际应用提供了一种途径。     

丝杠扭转刚度的探讨

精密传动,尤其是位置闭环的精密传动,必需计算传动链的刚度.本文从实际出发,讨论了由丝杠组成的传动链刚度问题,分析了传动链刚度对位置闭环控制的重要性,提出了计算丝杠传动刚度的量纲问题,最后推导了丝杠的扭转刚度与拉压刚度的量纲转换公式,利用量纲转换公式,可以很方便地计算出丝杠传动链的量纲.     

制造业信息技术应用之间的协同效应分析方法

应用信息技术是企业提高其竞争能力的重要手段之一。企业实施的各种信息技术应用通过信息集成组成企业的信息技术应用组合系统 ,各子系统相互配合而产生协同效应 ,使得系统总体功能可以大于各子系统功能之和。协同效应分析对于信息技术应用的可行性分析和企业信息技术应用水平的正确评价具有重要意义。本文给出的协同效应分析方法以计算机排样为例 ,首先通过信息技术应用的功能原理分析绘制待考察的应用与其它各种信息技术应用之间的数据流表 ,然后根据信息流表对协同系数进行估计 ,根据协同系数计算该信息技术的权数。最后说明了协同效应分析方法的应用价值。     

Radius dependence of solute concentration estimates of simulated ultrafine precipitates

Estimates of the radii and solute concentrations of simulated microstructures containing ultrafine spherical precipitates were determined from isoconcentration surfaces and proximity histograms. The accuracy of the estimates of the solute concentrations and the radii of precipitates was found to depend on the size of precipitates. Optimized parameters for analyzing 0.5‐ to 2‐nm‐radius precipitates are proposed. The solute content of 0.5‐nm‐radius precipitates was not estimated correctly by this method. The accuracy of the estimates of the solute concentration and the radius of precipitates were primarily influenced by the solute concentrations of the precipitates. The ranges of error of the solute concentration in the precipitates, which are associated with the analytical limitations of the ultrafine precipitates, were determined, and the results indicated a limitation of the estimates. Microsc. Res. Tech. 76:1196–1203, 2013. © 2013 Wiley Periodicals, Inc.     

Operation survivability of civil aircraft

The fulfillment of the standard requirements for fatigue and damage tolerance of aircraft structures is the basis for ensuring their safe operation. The paper analyzes the rules formulated in the U.S. FAA Standards and Recommendation Circulars, Soviet Airworthiness Standards, and Russian Aviation Rules. The main requirements for ensuring the damage safety, damage tolerance, and preventing widespread fatigue damages in operating aircraft structures are stated. The results of studying the multiple site damages of full-scale aircraft structures are presented. The principle of the staged increase in the service life limit of Russian aircraft is considered. The rules of Russia are noted to be harmonized with the rules of the United States and Europe. The values of design service lives, scales of fatigue tests of full-scale structures and flight times in operation of different aircraft types are presented. The required values of the statistical and cyclical fracture resistance of structural materials are substantiated, and the achieved values of these characteristics in modern aluminum alloys are presented.     

油膜振荡及稳定性分析

油膜振荡是大型机电设备出现重大故障的主要原因.轴承的运转状态也直接影响设备运行的稳定性.本文主要对机电设备中出现油膜振荡的特征及稳定性分析的方法加以总结分析,得出油膜振荡及稳定运行的区域,以尽可能地避免油膜振荡的产生,提高机电设备的利用率和生产效率,增加设备运行的稳定性,减少设备的维修时间.     

Scaling down of microequipment parameters

A method of micromechanical device fabrication is examined in this article. The method consists of the development of equipment which has sizes comparable with the sizes of the produced parts. There are different approaches to this problem. We propose a method of micromachine tool and micromanipulator creation. We do not use the expensive elements. To obtain the necessary precision we utilize the natural advantages of equipment of small size. In this article the error analysis of the microequipment is given and the methods of error minimization are described. An example of the developed microequipment prototypes is given.     

Concrete plasticity: Macro- and microapproaches

The development and the present state of some key aspects of the theory of concrete plasticity are summarized. Emphasis is placed on the representation and interpretation of the inelastic deformation of concrete materials in the postelastic range. The first part of the paper discusses the development of plasticity-based models in the prepeak stress range. A general formulation of softening behavior from the plasticity theory combined with the fracturing (damage) theory is then described. The difficulties of characterizing concrete deformations in the postpeak stress range led to an extensive study of the relationship between macrospace features and microscopic events in recent years. This is briefly outlined, and some key aspects of the development on strain softening and strain localization are reviewed. Against the background of this information, attempts are then made to develop an elastic-plastic-damage applicative model. Special emphasis is placed here on the practicality of the unified model combining the classical theory of plasticity with the modern theory of continuum damage mechanics. Some thoughts on possible numerical algorithms and program development for this type of model are also discussed. The role of cement-paste-sand interfaces in providing a deeper understanding of the behavior of concrete materials at the microscale are explored. Directions for further research are indicated.