大型体育馆建筑原地倒塌控制爆破

五里河体育馆是目前世界上拆除体育馆中最大型的建筑,总起爆炸药量达到2 568kg.通过对超大型体育馆爆破拆除方案、起爆网路、防护措施以及施工组织进行精心设计和施工,严格控制了工程的爆破震动、飞石等不利因素,采用了环保降尘泡沫技术,较大程度地降低了粉尘危害,实现了世界上首次超大规模的环保爆破.本工程的成功爆破,为今后此类大型建筑的环保控制爆破提供了成功的经验.     

大型离轴空间相机桁架支撑结构的设计

设计了一种18杆空间相机桁架式主支撑结构,解决了大型离轴三反空间相机主支撑结构要求同时具备轻质、高刚度、高强度和高热尺寸稳定性的难题。分析了采用整体框架结构及桁架支撑结构作为离轴三反空间相机主支撑结构的优缺点,根据光学系统及相机整体结构尺寸特点,确定了桁架支撑方案。分析对比了单层6杆桁架结构和双层18杆桁架结构的动静态刚度。合理选取了桁架式主支撑结构的材料,分析了对支杆基频的影响因素,优化设计了支杆的结构参数,分析了18杆桁架支撑结构的力、热特性,并对支杆与杆接头的胶粘结强度进行了试验测试。有限元分析结果表明,相机桁架主支撑结构一阶固有频率为78.4 Hz,次镜在X向重力作用下绕Y轴的最大倾角为4.6″,动静态刚度均满足设计指标要求。碳纤支杆拉伸试验结果表明,胶粘结支杆的抗拉强度为5.85 MPa,满足强度要求。     

122m下承式简支钢管混凝土曲弦桁梁结构制作

简要介绍了122 m跨度下承式简支钢管混凝土曲弦桁梁的结构制作工艺,重点介绍其中焊接工艺及控制焊接变形、保证焊接质量的措施。     

横风向共振对高烟囱爆破倾倒方向的影响

在顺风向荷载的基础上建立横风向荷载作用下高烟囱爆破倾倒的力学模型,分析了横风荷载对高烟囱定向爆破倾倒方向的影响,得到爆破倾倒偏转角的计算公式,并以南昌电厂210 m高烟囱为例进行验证.计算表明,烟囱共振频带在4～6级风的风振频率区域,定向爆破倾倒偏转角和风向角(0°～30 °)呈近似线性关系,随着风向角的增大,偏转角也随之增大,此外,考虑横风共振后倾倒偏转角显著增大,建议在设计爆破参数时应对横风荷载予以考虑.     

High Speed Imaging of Generation and Collapse of Multielectron Bubbles in Liquid Helium

We present experimental results on the generation and collapse of multielectron bubbles in liquid helium. By applying voltage pulses to a tungsten tip above the surface of the liquid, millimetre sized deformations were formed. Using high speed photography, we have imaged the disintegration of these deformations into bubbles of sizes ranging from ten to few hundred microns. At temperatures less than 2 K, the bubbles split into smaller bubbles and then disappeared in a time scale of few milliseconds. Smaller bubbles were formed at temperatures around 3 K, but were visible for more than hundreds of milliseconds. Although we have not been able to measure their charge directly, some of these bubbles responded to electric fields, implying these were indeed multielectron bubbles. With the existing theoretical picture, it is not possible to understand the strong dependence of the lifetime of multielectron bubbles on temperature.     

大跨距高楼房爆破拆除控制技术与倒塌形态分析

以立柱间跨距8.0 m×8.6 m、高70 m楼房爆破拆除工程为例,为保证临近在建楼房的安全,对倒塌建筑物落地冲击振动进行理论计算分析,并运用双切口加速楼房空中解体、分区块延期等爆破拆除控制技术实施拆除工程.通过爆破振动测试仪进行实时监控,利用高清摄像分析其倒塌形态,验证拆除控制技术的安全有效性.通过分析高清摄像照片和...     

High Temperature Residual Properties of Carbon Fiber Composite Sandwich Panel with Pyramidal Truss Cores

A study on the mechanical property degradation of carbon fiber composite sandwich panel with pyramidal truss cores by high temperature exposure is performed. Analytical formulae for the residual bending strength of composite sandwich panel after thermal exposure are presented for possible competing failure modes. The composite sandwich panels were fabricated from unidirectional carbon/epoxy prepreg, and were exposed to different temperatures for different time. The bending properties of the exposed specimens were measured by three-point bending tests. Then the effect of high temperature exposure on the bending properties and damage mechanism were analyzed. The results have shown that the residual bending strength of composite sandwich panels decreased with increasing exposure temperature and time, which was caused by the degradation of the matrix property and fiber-matrix interface property at high temperature. The effect of thermal exposure on failure mode of composite sandwich panel was observed as well. The measured failure loads showed good agreement with the analytical predictions. It is expected that this study can provide useful information on the design and application of carbon fiber composite sandwich panel at high temperature.     

同层位无时差双向折叠爆破新技术的应用

为解决倒塌场地受到制约的环境下有内通道、预制楼板的高层全剪力墙建筑物的爆破拆除,提出了同楼体同层位无时差("三同式")双向折叠爆破新技术,并在爆破拆除工程中进行了验证,成功实现了高层建筑物的上部楼体双向折叠爆破,对今后高层建筑物爆破拆除工程有很好的参考价值.     

上悬臂带弹支的高速转子振型平衡方法

提出一种具有弹性支承悬臂高速转子 (如碟片式分离机 )的快速整机动平衡技术的原理和方法。在理论上分析了这类转子进行振型分理平衡的可行性 ,并给出了满足平衡一、二阶振型在转鼓上、下加重面上加重的比例。经此方法平衡的离心机 ,平衡精度高 ,能在整个操作转速的范围内平稳运行     

高中生时间管理倾向、认知方式、元担忧水平对学业成绩的影响

综合探讨时间管理倾向、认知方式、元担忧水平的相互关系,以及三因子对学业成绩的相对影响作用。对123名高中生问卷调查表明:元担忧水平与时间效能感之间是显著的负相关;认知方式与学生的语文、数学、英语成绩呈显著正相关,时间效能感与学业成绩呈显著正相关;认知方式、元担忧水平对学业成绩的回归不显著,其是通过时间效能感对学业成绩产生影响。时间管理倾向对于学业成绩的回归效应存在显著学科差异。     

高中生主动性人格与职业生涯规划水平的关系:择业自我效能感和生涯适应力的作用

目的 随着生涯规划的普及,生涯教育的需求也逐渐提前,基于社会认知职业理论(SCCT),文本探索了高中生生涯适应力、择业自我效能感在主动性人格和职业生涯规划水平间的作用机制及其性别和家庭社会经济地位(SES)对其的影响.方法 本研究使用spss17.0和mplus7.0对810名高中生的问卷调查结果进行统计分析.结果(1...