OA:群雄缘何逐鹿

提起ERP、CAD、PDM或者财务软件，你总会立刻想起Oracle、SAP、利玛、并捷、和佳、金思维、用友、金蝶、UGS、PTC、欧特克、开目、艾克斯特、新洲、CAXA等等这些在行业内赫赫有名的软件厂商，但是提起OA，知道的人却少之又少，因此OA市场无“老大”也成了一个无需去争议的事实。     

农业大田信息监测系统

<正>1概述在现有的耕地及草场、绿化、林木、土地、山地、沙地上,按照需求布置相应测量点,对区域内不同深度的土壤温度、土壤水分等关系植、作物、林木等长势相关的土壤墒情信息,以及温度、湿度、光照、雨量、风速、风向、气压等空间环境信息的数据     

中国PROFIBUS & PROFINET协会组织(CPA)2011’技术论文大赛

鉴于PROFIBUS&PROFINET总线技术的先进性、成熟性和广泛的适用性,一直受到高度的关注和选择,并不断在我国石油化工、汽车、矿山、冶金、电力、交通、制药、水利、水处理、食品、楼宇等自动化领域广泛应用。国内许多自     

书讯

正《阀门手册——选型》——本书由化学工业出版社于2013年1月出版发行,张清双、尹玉杰、明赐东主编。全书针对阀门用户的实际需求,在介绍了各种阀门选型基本知识的基础上,重点介绍了各种阀门的结构、技术特点、应用场合及选用原则等内容,阀门种类包括闸阀、球阀、蝶阀、截止阀、止回阀、旋塞阀、柱塞阀、隔膜阀、电磁阀、节流阀、蒸汽疏水阀、减压阀、安全阀、调节阀、放料阀、塑料阀门、陶瓷阀门以及供水管网、水     

中核苏阀科技实业股份有限公司

正中核苏阀科技实业股份有限公司是在承袭中国核工业集团公司苏州阀门厂的品牌、质保、技术制造和管理诸优势的基础上创立的股份有限公司,拥有十五家集商贸、机械制造、生物技术、核辐射利用等子公司的大型企业。公司于1997年在深交所上市,公司证券代码000777。目前公司能制造碳钢、不锈钢、超低碳不锈钢、合金钢、蒙乃尔和钛等特殊合金材料的阀门,能够承接各类大工程阀门的订单。公司采用ANSI、API、MSS、JIS、BS、DIN、NF、GB和JB等标准进行阀门的设计、制造、测试和验收。     

CMF＇08＋CFF＇08力推中国锻压业发展——访中国锻压协会副秘书长齐俊河先生

记者：CMF’08和CFF’08即将开展，请您介绍一下本届展会的最新进展情况。齐副秘书长：截止到目前，本届展览会共有90多家一流的锻压设备、模具和材料的展商，分别来自中国、德国、日本、美国、意大利、法国、瑞典、西班牙和荷兰等十几个国家，包括舒勒、金丰、小松产机、隔而固、SMSMEER、Lasco、扬锻、徐锻、稼本、理研、湖州机床、     

润华集团ERP系统的澎湃力

润华集团股份有限公司是一家跨地区、跨行业的综合性大型股份制企业集团,山东省政府确定的全省首批51家现代企业制度试点单位之一.经营领域涉及汽车销售、汽车修理、配件供应、旧机动车交易、客运出租、汽车租赁、机动车拍卖、房地产开发、制药、进出口贸易、物业管理、广告企划等众多行业,并参股金融业,基本确立了以汽车服务业、药业、房地产业为支柱产业,投资、贸易、实业协调并进的发展格局.     

小常识

低碳经济包括的领域低碳经济几乎涵盖了所有的产业的领域。著名学者林辉称之为"第五次全球产业浪潮",并首次把低碳内涵延展为:低碳社会、低碳经济、低碳生产、低碳消费、低碳生活、低碳城市、低碳社区、低碳家庭、低碳旅游、低碳文化、低碳哲学、低碳艺术、低碳音乐、低碳人生、低碳生存主义。     

两项摩擦学科项目荣获2008年高等学校科学研究优秀成果奖

由钱林茂、肖旭东、周仲荣、雒建斌、孙庆平、温诗铸（完成人单位分别为：西南交通大学、香港科技大学、清华大学）主持完成的《纳米间隙中固一液界面微观粘着和摩擦的行为、机理与控制研究》和清华大学田煜、孟永钢、温诗铸、张敏梁、     

《现代科学仪器》征稿启事

《现代科学仪器》是在国家有关领导人和著名科学家的指导和大力支持下诞生的。它是中国科技核心期刊,是国内最重要的以介绍和评论国内外仪器为主的综合性科技期刊。读者对象为各行各业实验室、试验室、研究室应用与维护仪器的科技人员及购置与管理仪器设备的人员;从事高技术及其产品研制生产的科技人员;各级有关管理决策人员;大专院校师生等。涉及物理、化学、生物、医疗卫生、制药、农业、地矿、机械、电子、石油、化工、冶金、能源、交通、环保、建筑、轻工、商检、技术监督等各项科技领域。     

Modeling and control of an electronic-vacuum booster for vehicle cruise control

A mathematical model and control laws for an Electronic-Vacuum Booster (EVB) For application to vehicle cruise control will be presented. Also this paper includes performance test result of EVB and vehicle cruise control experiments. The pressure difference between the vacuum chamber and the apply chamber is controlled by a PWM-solenoid-valve. Since the pressure at the vacuum chamber is identical to that of the engine intake manifold, the output of the electronic-vacuum booster is sensitive to engine speed. The performance characteristics of the electronic-vacuum booster have been investigated via computer simulations and vehicle tests. The mathematical model of the electronic-vacuum booster developed in this study and a two-state dynamic engine model have been used in the simulations. It has been shown by simulations and vehicle tests that the EVB-cruise control system can provide a vehicle with good distance control performance in both high speed and low speed stop and go driving situations.     

Three-dimensional flow characteristics of propeller-propulsion WIG effect vehicle with direct underside pressurization

Numerical investigations for a 3-dimensional WIG effect vehicle with DUP (direct underside pressurization) have been performed. The purpose of this study is to analyze the aerodynamic characteristics and static height stability of DUP using computational fluid dynamics (CFD). When a WIG effect vehicle accelerates to take off on water, increased pressure under the fuselage by DUP (propeller and air chamber) can considerably reduce the take-off speed and thus minimize the effect of the hump drag which is one of the technical difficulties of a WIG effect vehicle. The accelerated air by the propeller enters the air chamber through a channel in the middle of the fuselage resulting in an augmentation of the lift by changing the air pressure from dynamic to static. However, the DUP is not favorable for both stability and aerodynamic performance of the WIG effect vehicle because the accelerated air produces an excessive drag, negative pitching moment and 3-dimensional effects (that is, yawing and rolling moments). The result shows that the effect of yawing and rolling moments is not serious.     

制动气室推杆行程故障诊断

推杆行程失调会引起客车制动力的损失,使制动力矩减小,针对此问题提出了一种诊断制动气室推杆行程失调故障的方法。分析了气制动系统中的制动总阀和制动气室的工作状态,利用模型对制动气室伸出推杆的行程值进行理论估计,通过判断估计值是否落在规定的推杆有效行程范围内,对系统是否存在推杆行程失调故障进行判断。然后搭建了整车气压制动系统模拟试验台,针对整车制动系统进行制动性能模拟试验,对制动气室的气压变化量进行测量,将归一化后的试验值与理论值进行比较,对气制动系统是否存在推杆行程失调进行了诊断。试验结果表明,该模型能很好地对气制动系统推杆行程失调进行故障诊断。     

基于AMESim的气压ABS调节器建模与调节特性分析

为了提高汽车气压ABS制动系统的安全性和可靠性,从气压ABS调节器的基本结构和工作特性入手,采用AMESim平台建立气压ABS调节器模型并对其调节特性进行分析,具体围绕共性能参数、制动气室压力变化的静态特性与动态特性进行研究。     

Study on the damping performance characteristics analysis of shock absorber of vehicle by considering fluid force

In this study, a new mathematical dynamic model of displacement sensitive shock absorber (DSSA) is proposed to predict the dynamic characteristics of automotive shock absorber The performance of shock absorber is directly related to the vehicle behaviors and performance, both for handling and ride comfort The proposed model of the DSSA has two modes of damping foice (i e soft and hard) according to the position of piston In this paper, the performance of the DSSA is analyzed by considering the transient zone for more exact dynamic characteristics For the mathematical modeling of DSSA, flow continuity equations at the compression and rebound chamber are formulated And the flow equations at the compression and rebound stroke are formulated, respectively. Also, the flow analysis at the reservoir chamber is carried out Accordingly, the damping force of the shock absorber is determined by the forces acting on the both side of piston The analytic result of damping force characteristics are compared with the experimental results to prove the effectiveness Especially, the effects of displacement sensitive orifice area and the effects of displacement sensitive orifice length on the damping force are observed, respectively The results reported herein will provide a better understanding of the shock absorber     

高空、低速、低雷诺数对发动机部件及整机性能的影响研究

为研究FWS-9发动机作为高空无人飞行平台动力装置的可行性,在对发动机旋转部件(压气机、涡轮)雷诺数修正的基础上,研究了高空、低速、低雷诺数对发动机部件(风扇、压气机、主燃烧室和涡轮)和整机性能、稳定性的影响规律。     

Cushion pressure control system for an intelligent air-cushion track vehicle

This paper presents the control system of cushion pressure for the developed intelligent air-cushion track vehicle (IACTV) for operating on swamp terrain and wet fields. A novel auto-adjusting supporting system is designed for the vehicle’s intelligent air-cushion system. Focusing on minimizing the total power demand of the vehicle, an optimization model has been established, for examining the effects of vehicle parameters and load distribution on power consumption by controlling air-cushion pressure. Then optimum cushion pressure is determined based on the developed optimum pressure — sinkage relationship and the pressure in the cushion chamber is controlled by the Fuzzy controller by maintaining volume flow rate and continuously monitored by the pressure sensor attached with the cushion chamber. The ultrasonic displacement sensor is used to measure the sinkage of the vehicle. The output voltages of the ultrasonic displacement are used to operate the pull-in solenoid switch through the microcontroller which closes the circuit of the compressor motor. Distribution of vehicle load to the air-cushion system is controlled by Fuzzy Logic controller by maintaining the inside pressure of the cushion.     

车辆制动气室动态响应特性的无因次分析

制动气室是车辆气压制动回路的关键组成部分,其动态响应特性直接影响车辆气压制动系统性能,建立制动气室充气过程数学模型,并通过实验验证模型的正确性。将制动气室的流量特性方程、状态方程以及活塞盘的运动方程无因次化,得到制动气室无因次解析模型,仿真计算出气室压力响应和运动特性变化规律。研究结果表明:制动气室回位弹簧满载弹力、橡胶膜片的膜片力等参数均会对气室响应特性造成不同程度影响,其中回位弹簧满载弹力的影响程度最大,但不同参数下气室的充气时间基本保持恒定。     

单气室油气弹簧阻尼特性及其影响因素分析

针对某重型特种车辆平顺性研究中单气室油气弹簧阻尼特性的研究问题,基于薄壁小孔理论和范德瓦尔实际气体状态方程,同时根据单气室油气弹簧的结构特点和阻尼的组成建立了相应的阻尼力特性模型,并推导了阻尼系数方程。利用MATLAB软件进行仿真,研究了单气室油气弹簧阻尼特性以及激振频率、幅值、自身结构参数对阻尼系数速度特性的影响。研究结果表明:单气室油气弹簧阻尼特性具有较好的非线性,在压缩阶段的阻尼力较拉伸阶段的大,能够较好地缓解冲击,达到减振效果从而改善车辆行驶平顺性;激振频率和幅值属于外因,仅影响阻尼系数的取值范围,而对其取值及曲率几乎无影响;阻尼系数随活塞杆外径、油管直径的减小而增大,随油管长度的减小而减小。研究结果能对整车振动特性研究中阻尼参数的选取及油气弹簧阻尼特性设计优化等工作提供较为系统的理论支持。     

热动力系统性能参数预测与理论分析

为了增加航行器的航程和优化航行器各种仪器的工作条件 ,航行器的航速应不断发生变化 ,这就需要解决航行器在慢速航行时 ,热动力系统的性能和结构参数的配置问题。本文以热动力系统总体参数为出发点 ,对热动力系统中的发动机、燃烧室及燃料供应分系统的参数配置进行了预测和理论分析。本文可为水下航行器的航速设计及计算方法提供参考。