铜基粉末冶金摩擦材料高温疲劳磨损规律

研究了高速列车用铜基粉末冶金多孔摩擦材料的高温摩擦磨损性能。在PlintTE77高温疲劳试验机上对该材料进行了高温磨损性能测试 ,工况分别为 :室温 ,10 0℃ ,2 0 0℃ ,3 0 0℃ ,3 5 0℃ ,5 0 0℃ ;法向载荷为 :2 0 0N ,45 0N ,等12种工况 ;振动频率为 :4Hz ;移动幅值为 :± 5mm ;并对摩擦后的磨痕进行了SEM分析 ,发现 :(1)在 2 0 0N ,3 0 0℃时出现了粘压的多源弧形裂纹 ,这和冲击时的沿树枝晶裂纹截然不同 ;(2 )在 45 0N ,3 0 0℃时 ,磨痕表面出现了球状的石墨颗粒层 ,这起到了极好的润滑作用 ,使得 3 0 0℃时磨损较低。 (3 )在 45 0N ,3 5 0℃时 ,有沿磨痕方向的长条裂纹出现 ;(4 )在不同荷载 5 0 0℃时 ,发生了负磨损 ,即摩擦材料粘附到对偶材料上 ,由于新的氧化面的形成摩擦系数是最高的。根据以上分析粗略拟合了该材料的磨损规律     

DX12000×1000大面铣床设计构想

从经济性、实用性以及加工质量方面对铸铝母线的大面积铣削进行了简要分析 ,设计确定了 DX1 2 0 0 0× 1 0 0 0大面铣床的结构以及技术参数 ,并对其使用效果进行了简介     

提高企业竞争力 再铸新的里程碑——柳工机械1至10月创产销超万台纪录

柳工人多年梦寐以求年产销量达到万台的目标 ,于 2 0 0 3年 1 0月金秋胜利实现了。这是 2 0 0 3年 1 1月 3日上午 ,柳工公司领导在公司举行的“柳工产销双双突破万台庆典”仪式上宣布的一个奇迹。柳工取得这样辉煌的成就 ,是柳工几代人团结拼搏和不懈努力的结果 ,为庆祝柳工创建 45周年、股票上市 1 0周年献上了一份厚礼。2 0 0 3年以来 ,柳工紧紧抓住市场旺销的大好时机 ,内抓挖潜保质量 ,外抓市场促畅销 ,有效地促进了产销两旺的新局面。 1月至 1 0月 ,公司累计生产工程机械产品 1 0 5 0 0台 ,销售整机 1 0 1 0 0台 ,同比分别增长5 5 .1 %…     

刀具图形管理系统的可视化

为了实现图形数字化 ,进而实现图形资源共享 ,本文在Windows2 0 0 0环境下 ,以Solidworks2 0 0 0为图形平台 ,用Vi sualBasic6 .0和Access2 0 0 0为数据库开发工具 ,开发了刀具参数化图形管理系统 ;并在所编刀具可视化图形管理系统的基础上 ,建立了动态的可视化刀具图形管理系统。该系统除了实现各刀具图形及参数的可视化外 ,还可以通过采用对话框形式根据实际情况实现系统的数据库查询和更新的可视化。     

一种现场总线控制系统组态调试工具的设计

SHCAN2 0 0 0是基于 CAN总线开发的分布式现场总线控制系统。分析了 SHCAN2 0 0 0现场总线控制系统的体系结构。探讨了用于现场智能仪表的组态调试技术 ,介绍了一种现场总线控制系统组态调试工具—— SHCANCFG的设计思想及其软件的主要结构。提出了 SHCANCFG中解决数据通信方式、现场智能仪表组态数据和参数的编辑和集中管理、数据格式的转换、数据的下载和上传等问题的方法。同时 ,介绍了 SHCANCFG中的各种结构模块的设计思想。 SHCANCFG已在SHCAN2 0 0 0现场总线控制系统的工程实际应用中发挥了作用     

ISO14000环境管理体系与链式效应

阐述了在未来全球经济快速发展的趋势下 ,ISO140 0 0环境管理体系实施的重要意义。着重介绍了我国实施ISO140 0 0标准的现状及未来企业发展与ISO140 0 0标准的密切关系     

贯彻执行ISO9000标准是企业管理的关键

本文主要阐述了在企业转型改革过程中执行ISO 90 0 0标准的重要作用 ,介绍了ISO 90 0 0标准的主要结构。     

基于知识的格栅除污机快速设计系统

以UGⅡ 1 6 0 /(WindowsNT/2 0 0 0版 )为开发平台 ,采用UG/OpenAPI和MicrosoftVisualC 6 0作为开发工具 ,开发了基于知识的格栅除污机快速设计系统。详细介绍了系统的组成及实施的关键技术。     

北美起重机市场现状

近年来 ,北美起重机市场很不乐观。据统计 ,2 0 0 2年北美市场销售的液压伸缩臂移动式起重机比上年下降了15 %。 2 0 0 2年 7月 ,其共销售了移动式液压起重机 6 0台 ,创下了历史最低记录。 2 0世纪 70年代 ,是北美销售移动式起重机最多的时期 ,每年销售移动式起重机达 5 0 0 0台。去年 ,北美不平路面起重机销量也比 1998年减少了大半 ;汽车起重机的销量比 2 0 0 1年下降了 5 0 % ;履带式起重机比 2 0 0 1年下降 15 %～ 2 0 % ;其他型号的起重机销量也下降明显。在北美市场中销售的汽车起重机有索福特公司的 4 0t型、欧克尼公司的 6 0t型、黎…     

中国汽车工业步入高速增长的阶段

中国汽车工业步入了一个高速增长的阶段。在 2 0 0 3年度中国汽车工业发展论坛上 ,中国汽车工程学会理事长张小虞说 ,2 0 0 3年是中国汽车工业建立 50周年 ,在这 50年中 ,中国汽车工业经历了从无到有、从小到大和正在从大到强的变化。这 50年里 ,中国汽车工业发展的加速趋势明显 :从 1953年到 1992年 ,中国汽车工业达到 10 0万辆产量花了近 40年时间 ;从 1992年到 2 0 0 0年 ,完成从 10 0万辆到 2 0 0万辆的增长 ,用了 8年时间 ;从 2 0 0 0年到 2 0 0 2年底 ,实现从 2 0 0万辆到 3 0 0万辆的增长 ,用了两年时间 ;而根据今年前三季度的统计预…     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

Book Reviews

Book reviewed in this article: Advanced Scanning Electron Microscopy and X-ray Microanalysis . By Dale E. Newbury , David C. Joy , Patrick Echlin , Charles E. Fiori and Joseph I. Goldstein A Scanning Electron Microscope Atlas of the Honey Bee . By E. H. Erickson , S. D. Carlson and M. B. Garment Electron Microscopy of Proteins , Volume 5. Viral Structure . Edited by James R. Harris and Robert W. Horne Filtres Optiques . by M. Françon Optique Géometrique, Matricielle et Ondulatoire . By J. Ph . Pérez     

Research on the calibration method of precipitation micro- physical characteristics sensor

In order to diminish the effect of the ambient light and CCD pixel non-uniformity to the Precipitation Micro-physical Characteristics Sensor,a modified calibration scheme was designed and calibration experiments in sunny,cloudy,night,different location of sample space were carried out. Firstly,the characteristics of particle images which affected by ambient light and different location of sample space were analyzed. Secondly,the relevance betw een particle image features and parameters of image processing were discussed. Finally,the parameter setting scheme were determined,the radium of median filtering algorithm is 3 pixels,the defocusing radius of point spread function( PSF) is 7 pixels,the radium of erosion is 3 pixels,and the binary threshold is obtained from the Area-thresh relationship. The results show that the new scheme could deal with the image calibration well,the average errors of equivolumetric diameter was 0. 041 mm with standard deviation of 0. 115 mm,and the average errors of the axis ratio was 0. 011 with standard deviation of 0. 085. The new scheme works well in the field observation too,the observed axis ratio is consistent with the empirical relationship that proposed by Beard. The relative error of accumulation precipitation is-3. 06% after calibration,w hich is improved 1. 94% low er than the initial one without calibration.     

Estimation of surface area and length with the orientator

The orientator is a new technique for the estimation of length and surface density and other stereological parameters using isotropic sections. It is an unbiased, design-based approach to the quantitative study of anisotropic structures such as muscle, myocardium, bone and cartilage. A simple method for the practical generation of such isotropic planes in biological specimens is described. No special technical equipment is necessary. Knowledge of an axis of anisotropy can be exploited to optimize the efficiency. To randomize directions in space, points are selected with uniform probability in a square using various combinations of simple random, stratified random, and systematic random sampling. The point patterns thus produced are mapped onto the surface of a hemisphere. The mapped points define directions of sectional planes in space. The mapping algorithm ensures that these planes arc isotropic, hence unbiased estimates of surface and length density can be obtained via the classical stereological formulae. Various implementations of the orientator are outlined: the prototype version, the orientator-gencrated ortrip, two systematic versions, and the smooth version. Orientator sections can be generated without difficulty in large specimens; we investigated human skeletal muscle, myocardium, placenta, and gut tissue. Slight practical modifications extend the applicability of the method to smaller organs like rat hearts. At the ultrastructural level, a correction procedure for the loss of anisotropic mitochondrial membranes due to oblique orientation relative to the electron beam is suggested. Other potential applications of the orientator in anisotropic structures include the estimation of individual particle surface area with isotropic nucleators, the determination of the connectivity of branching networks with isotropic disectors, and generation of isotropic sections for second-order stereology (three-dimensional pattern analysis).     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Friction-induced ignition modeling of energetic materials

The heat released during the external frictional motion is a factor responsible for initiating energetic materials under all types of mechanical stimuli including impact, drop, or penetration. We model the friction-induced ignition of cyclotrimethylenetrinitramine (RDX), cyclotetramethylene-tetranitramine (HMX), and ammonium-perchlorate/ hydroxylterminated-polybutadiene (AP/HTPB) propellant using the BAM friction apparatus and one-dimensional time to explosion (ODTX) apparatus whose results are used to validate the friction ignition mechanism and the deflagration kinetics of energetic materials, respectively. A procedure to obtain the time-to-ignition for each energetic sample due to friction is outlined. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Min-cheol Gwak received his B.S. degree in Mechanical Engineering from Korea Aerospace University, Korea, in 2007. Now he is a graduate student of Mechanical and Aerospace Engineering at Seoul National University in Seoul, Korea. His research interests are ignition of high energy material and combustion phenomena. Tae-yong Jung received his B.S. degree in Mechanical and Aerospace Engineering from Seoul National University, Korea, in 2007. Now he is a graduate student of Mechanical and Aerospace Engineering at Seoul National University in Seoul, Korea. His research interests are solid propellant combustion and phase transformation. Professor J. Yoh received his BSME from UC Berkeley in 1992 and MSME from UCLA in 1995. His doctoral degree is in Theoretical & Applied Mechanics from the University of Illinois at Urbana-Champaign, 2001. His research interest is in high energy system design using high power lasers and condensed energetic materials.     

New research trends on high-precision time transfer technology

High-precision time transfer plays an important role in the areas of fundamental research and applications. Accompanying w ith the remarkable improvements in the ability of generating and measuring high-accuracy time-frequency signal,seeking for new time-transfer techniques betw een distant clocks w ith much further improved accuracy attracts attentions w orld-w idely. The time-transfer technique based on optical pulses has the highest precision presently,and the further improvement in the accuracy is heavily dependent on the time-domain properties of the pulse as w ell as the sensitivity of the applied measurement on the exchanged pulse. The application of optical frequency comb in time transfer for a precision up to femtosecond level are currently the focus of much interest,and has recently achieved many breakthroughs. Further investigations show that,utilizing quantum techniques,i.e. quantum measurement technique and quantum optical pulse source,can lead to a new limit on the measured timing information. Furthermore,it can be immune from atmospheric parameters,such as pressure,temperature,humidity and so on.Such quantum improvements on time-transfer have a bright prospect in the future applications requiring extremely high-accuracy timing and ranging. The potential achievements w ill form a technical basis for the future realization of sub-femtosecond time transfer system.     

QUALITY CONTROL OF SEMICONDUCTOR PACKAGING BASED ON PRINCIPAL COMPONENTS ANALYSIS

5 critical quality characteristics must be controlled in the surface mount and wire-bond process in semiconductor packaging. And these characteristics are correlated with each other. So the principal components analysis(PCA) is used in the analysis of the sample data firstly. And then the process is controlled with hotelling T2 control chart for the first several principal components which contain sufficient information. Furthermore, a software tool is developed for this kind of problems. And with sample data from a surface mounting device(SMD) process, it is demonstrated that the T2 control chart with PCA gets the same conclusion as without PCA, but the problem is transformed from high-dimensional one to a lower dimensional one, i.e., from 5 to 2 in this demonstration.     

OPTIMIZATION METHOD ON IMPELLER MERIDIONAL CONTOUR AND 3D BLADE

An optimization method for 3D blade and meridional contour of centrifugal or mixed-flow impeller based on the 3D viscous computational fluid dynamics (CFD) analysis is proposed. The blade is indirectly parameterized using the angular momentum and calculated by inverse design method. The design variables are separated into two categories: the meridional contour design variables and the blade design variables. Firstly, only the blade is optimized using genetic algorithm with the meridional contour remained constant. The artificial neural network (ANN) techniques with the training sample data schemed according to design of experiment theory are adopted to construct the response relation between the blade design variables and the impeller performance. Then, based on the ANN approximated relation between the meridional contour design variables and impeller performance, the meridional contour is optimized. Fewer design variables and less calculation effort is required in this method that may be widely used in the optimization of three-dimension impellers. An optimized impeller in a mixed-flow pump, where the head and the efficiency are enhanced by 12.9% and 4.5% respectively, confirms the validity of this newly proposed method.