水泥混凝土路面防滑问题初探

分析了影响水泥混凝土路面防滑的主要因素 ;对材料特征进行了理论分析 ;提出了提高路面抗滑能力的技术措施     

EFFECTS OF BERBAMINE ON CONTRACTION AND Ca2＋INFLUX OF ISOLATED BASILAR ARTERY AND THORACIC AORTA IN RABBITS

ＥＦＦＥＣＴＳＯＦＢＥＲＢＡＭＩＮＥＯＮＣＯＮＴＲＡＣＴＩＯＮＡＮＤＣａ２＋ＩＮＦＬＵＸＯＦＩＳＯＬＡＴＥＤＢＡＳＩＬＡＲＡＲＴＥＲＹＡＮＤＴＨＯＲＡＣＩＣＡＯＲＴＡＩＮＲＡＢＢＩＴＳＬｉＬｅ（李乐）；ＺｈａｎｇＣａｉｌｉｎｇ（张彩玲）；Ｚｈｕａｕｇ...     

华利微型电动汽车的设计研究

随着人们环保意识的增强，对电动汽车的呼声日益高涨，天津市汽车研究所经过反复研究后，对华利微型厢式车进行了改装，并取了一定的成绩。     

利用国际贷款采购机械设备时国际竞争招标中一些问题的探讨

公路建设中使用国际贷款的项目日益增多,使用此类贷款的采购包括劳务采购和物资(机械、材料)采购.机械设备采购已进行多年,其中包括日本海外协力基金组织(简称为O.E.C.F.)资金和世界银行(World Bank)资金的采购.O.E.C.F.及世界银行均推荐,除     

水泥混凝土路面断板的处理

水泥混凝土路面产生的不规例的断缝(断板),目前还没有较好的处理方法。经过几个工程不同处理方法的对比,认为在哈大线一期四标段水泥混凝土路面工程中断板的处理是较成功的。     

德国电动汽车发展特点

<正>德国联邦总理默克尔早在三年前就已经宣布,到2020年德国运营或行驶的电动汽车要达到100万辆。但据德国联邦机动车署提供的统计数字,2012年元月德国上牌的电动汽车总共只有4541辆,而且绝大部分还是试验用车,车主是环保组织或电力生产部门的。真正属于私人的电动汽车仅有区区101辆。那么这是否意味着默克尔的预言或德国政府的目标要落空呢?尽管部分业内人士有这种担心和忧虑,但目前就做出这种结论,恐怕为时过早。一、政策扶持为了推动电动汽车的发展,抢占全球电动     

基于人机界面的PLC控制系统的仿真研究

文章介绍的是一种基于人机界面的PLC控制系统的仿真平台。该平台利用人机界面的互动性,通过其开发、编辑软件,使用户可以方便快捷地为PLC控制系统设计和建立仿真模型,并可对系统进行调试。实验表明,该仿真平台可用于PLC控制系统的开发。     

浅谈公路工程质量监督

公路工程质量监督的概念、性质地位处于三级质量保证体系的重要位置,质量监督是行政执法和技术执法需要依法行政依据。     

Finite Element Optimization of Vee-ring Factor in Fine-blanking Process

The vee-ring is one of the most characteristic features of the fine-blanking process which is derived from the conventional blanking. With the vee-ring, a counter plate and some other working parameters, a component with a precise geometry and smoothly blanked surface can be produced without any major secondary operations. However, these working parameters are always empirically determined or determined by trial-and-error method, which is time-consuming and expensive. In this study, a numerical simulation method was used to analyze the effect of vee-ring factors on product quality, such as distance between vee-ring and punch, vee-ring height and blank holder force, so as to obtain as high clean cut ratio as possible. During the simulation, the model was assumed as axisymmetric one and the workpiece was considered as rigid plastic material, meanwhile the tools were defined as rigid bodies so as to shorten the computational time. A damage model taking into account the influence of hydrostatic stress was used to simulate material fracture in fine-blanking. The result obtained from the simulation indicated that with the help of vee-ring, the metal material near the shear band does not flow with the punch penetration and high compressive stress in the shear band is generated. Consequently, higher clean cut ratio can be obtained with a vee-ring model than the one obtained with a plane blank holder model. Furthermore, the longer the distance between vee-ring and punch is, the higher the height of roll-over becomes.