塔式起重机超长附着撑杆内力的简易计算

本文通过对塔机附着架的受力分析,推导出塔机附着架合作用力S及各撑杆内力最大值的简便计算公式,供施工单位在塔机超长附着强度验算时参考。     

Numerical Simulations on Geometrical Properties of Wall attaching Transonic Jet

Effects of operating conditions and device’s geometrical sizes on geometrical properties of wallattaching transonic jet between two parallel plat plates are numerically simulated. Conclusions are as follows: 1) Upriver part of the wallattaching jet’s center streamline is in good accordance with parabola; 2) When both gas inlet pressure and outlet pressure as well as their ratio are not too high ( the outlet pressure is less than 10 MPa and the pressure ratio is less than 3), the center streamlines of the wallattaching jet with the same pressure ratio coincide with each other very well, and the deflection degree of the center streamline decreases with rise of the pressure ratio; 3) The deflection degree of the jet’s center streamline decreases with either broadening of nozzle’s throat or rise of wall offset; 4) With rise of the pressure ratio, attachment distance of the jet increases, but the increase rate descends; 5) The attachment distance ascends with rise of either the nozzle’s throat or the wall offset.     

Low-Energy Electron Damage to Condensed-Phase DNA and Its Constituents

The complex physical and chemical reactions between the large number of low-energy (0–30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.     

放心家居装饰设计

从“家是放‘心’的地方”这句房产广告词说起,阐述了家居装饰设计应让“家”具有和谐的归属感、温暖的舒适感,才能放“心”,而不是一味追求“个性化”、“时尚化”,结合多年的设计与施工实践,从家居各个空间的设计和施工,对此进行了探讨,以供设计者参考。     

模糊数学在湖泊水质富营养化评价中的应用

运用模糊数学的基本思想方法,研究了我国湖泊的富营养化状况,并根据湖泊水质评价标准建立相应的隶属函数表达式,再通过计算权重,建立模糊关系矩阵,最后应用模糊综合评判模型进行合成运算,说明此法的合理性和可靠性.     

现有桥梁的可靠性分析

为了准确地把握现有城市公路桥梁的损伤程度,将桥梁评定单元划分为下部结构、支座、上部结构及桥面系等4个组合项目,每个项目包含若干个子项,从而形成子项、项目和单元3个层次,每个层次划分为4个等级.在各个层次上,直接对可靠性进行评级.组合项目的等级评定中引用了故障树的逻辑原理来表示构件可靠性和结构可靠性之间的关系,采用了传力树评级法.同时,把工程模糊论方法应用到结构可靠性分析中,按危险点所占比重划分桥梁组成部分的评定等级,由各组成部分的危险构件百分数可得到构件对各等级的隶属度,从而构成桥梁等级的评判矩阵.通过模糊矩阵的复合运算,对桥梁的危险性进行鉴定,为维护与加固的合理决策提供依据.     

磁性固位体磁场的有限元分析

磁性固位体是一种应用于口腔及颌面修复的新型医疗器件。本文采用有限元法对磁性固位体的磁场进行分析 ,将麦克斯韦张量法与虚位移法的计算结果与实验值进行比较 ,通过对固位体固位力地计算得到合适的固位体尺寸。在DELPHI5 .0环境下编制了一套通用的可视化二维有限元软件     

悬挂靶板在高速弹丸冲击下的运动

为研究航天器外挂设备受到微流星或空间碎片的高速撞击后产生的运动规律和物理现象，通过将航天器外挂设备（太阳能帆板或天线等）模拟为简单悬挂板，得到悬挂板扬角与撞击速度、弹丸直径、材料屈服强度及悬挂板厚度之间的关系曲线。结果表明在特定条件下悬挂板并沿着弹丸运动方向上扬而是朝反方向做上扬运动，悬挂板朝弹丸运动方向的上扬角是有限的，相反其反向扬角在特定条件下无限制增长。     

憎水性涂料在输电线路防冰中的应用前景

论述憎水性化学涂料防冰的原理,评论憎水性化学涂料防冰的有关的研究、应用现状和前景,提出虽然目前现有的防冰涂料具有憎水性,但其接触角一般小于130°,疏水特性仍满足不了输电线路防冰的要求,因此在输电线路防冰中的效果不明显。为使化学涂料具有较好的防冰效果,应使其接触角大于170°。在自然界中,荷叶具有这一特性,仿荷叶涂料在输电线路防冰中具有较好的前景。     

微动力复合生物污水处理系统的研究

微动力复合生物污水处理系统是在传统生物处理工艺基础上开发出的新型微动力固定床复合生物反应器,反应器中同时存在活性污泥（悬浮相）和生物膜（附着相）两类多种微生物。通过充分发挥附着相和悬浮相多种微生物消解、转化能力,增强对废水中COD、BOD的去除效果。