顶推法施工的曲线连续梁桥截面实测应力分析

在采用顶推法施工的曲线连续梁桥的主梁内预埋的钢筋计测得的混凝土应力远大于理论经计算结果,这主要是由混凝土收缩徐变变形中的非弹性变形包含在钢筋计中引起的。本文提出了用于扣除混凝土实测应力中收缩徐变非弹性变形影响的两种计算方法,并且将徐变对实测应力影响计算进行了特殊考虑,在一座大桥进行施工监控中使用取得了较好的效果。     

基于Simulink单相矩阵变换器畸变的改进措施研究

基于单相矩阵变换器原理图得到产生畸变的输出波形，并进一步分析了输出波形畸变的原因，提出了改进思路以及改进电路图，最终通过Simulink的建模仿真得到了单相矩阵变换器理想的输出波形，并发现这种变换器具有输出频率连续可调、输入输出电流接近正弦波等优点，发展前景大，值得进一步研究．     

Numerical Analysis of Thermal Distortion and Residual Stresses in H13 Steel Due to Vacuum Gas Quenching

IntroductionVacuumgasquenchinginvolvinghighpressuregasasacoolingmedium,is.anincreasinglypoPularheattreatffienttechniquefor1argesteeldieblocks,forexamPleHl3die.ItisconsideredessefltialtounderstandthentheeofthegasflowandtheinfiuencethishasontemPeratureprofilesandresultaflresidualstresseswithintheheattTeatedcomPonent.SimulatingthisprocessinvolvesthesimulationofgasflowinthefurnaceaswellasthesimulationofthethermalbehaviourofthecomPoneni.However,thereisnosinglecomPatersoftwarepackageavailabletot…     

Experimental and numerical investigation on welding simulation of long stiffened steel plate specimen

The paper presents the results of metal inert gas T-joint fillet welding tests of small scale rectangular stiffened steel plates longer than the standard test specimen. In the literature the focus is typically on plates with a small aspect ratio and the present work deals with plates of higher aspect ratio, which are the typical ones in marine structures, aiming to determine if there is any significant effect of welding along the longitudinal direction. Nonlinear thermo-elasto-plastic finite element models are adopted to evaluate the temperature distribution, welding induced distortions and residual stress in the stiffened plates of shipbuilding steel. Given the difficulty in data acquisition of temperature-dependent properties of the material, a simplified model of the properties is proposed, based on the values at room temperature. Good agreement is observed between the measured and simulated temperatures, indicating that the current finite element approach is appropriate to simulate the welding process. The proposed simplified material model can be efficiently used in the finite element analysis of welded steel structures. It is concluded that the welding parameters have more significant influence on the structural responses than the dimension of the plate.     

模块化大型钢结构焊接变形控制

重点研究如何控制模块化大型钢结构焊接期间的变形.以Koniambo镍矿项目为例,详细分析焊接变形产生的原因,对出现的焊接变形的类型进行了归纳.提出在建造过程中为控制焊接变形须采取的必要措施.     

调幅话信号时分干扰效果研究

针对时分多目标干扰效果的影响因素,从功率角度对其进行了公式推导,以干扰机发射功率、干扰占空比为变化参数,以话音可懂度、频谱失真测度为干扰效果评判指标,建立了调幅话信号时分法干扰仿真模型,通过仿真计算,得出了干扰机发射功率、干扰占空比与干扰效果的关系。     

路面平整度对水泥混凝土路面板变形的影响规律研究

根据荷载频率与路面空间频率之间相互关系这一纽带,得出了在车速一定的条件下,水泥混凝土路面板的最大位移随路面空间频率的变化规律,具有一定的理论价值。     

脱空地基上连续配筋混凝土路面板的扭转研究

根据连续配筋混凝土路面板扭转等效原则,转换了板横向裂缝处车辆集中荷载的作用模式。采用弹性薄板理论,提出了车辆集中荷载作用下脱空的连续配筋混凝土路面板的扭转角与扭转位移计算公式,并采用有限元分析结果对公式计算值进行了对比验证,可供工程技术人员参考。     

基于端到端失真优化的无线视频联合编码方案

在无线视频传输环境端到端失真分析的基础上,针对H.264视频流建立了一种新的端到端失真模型.在使用LDPC信道编码方式与该失真分析模型的基础上,提出了一种基于端到端失真优化的联合信源信道编码方案.该方案根据当前无线信道的信噪比与信道带宽等状态信息,自适应地调节信源编码量化参数和信道编码码率,使端到端失真最小.实验结果表明,与固定码率编码相比,本文提出的联合信源信道编码方案可在不增加带宽的情况下显著提高视频传输质量.     

遂平制梁场沉降观测

结合遂平制梁场工程,系统地介绍箱梁预制场台座沉降观测和箱梁徐变观测的方法,并从测点布置、观测周期等方面进行深入阐述,对于类似工程具有一定的参考价值。