既有线32 m下承式钢板梁加固方案的车-桥动力仿真分析

为配合沪宁线250 km·h-1提速改造工程,运用车桥耦合振动方法,从车辆和桥梁动力响应角度,对一挠跨比、跨中梁体横向振幅及横向加速度均超过<铁路桥检规>通常值的32 m下承式钢板梁进行加固方案比选.车-桥仿真计算结果表明:加强主梁可以明显提高桥梁的竖向刚度和横向刚度,降低车辆的轮重减载率和车体垂向加速度;增加横向连接系措施可以降低桥梁横向振动加速度;当车速超过220 km·h-1时,可降低车辆的脱轨系数;2种桥梁加固措施几乎不改变车体横向加速度;同时采取加强主梁和增加横向连接系的不同加固方案的效果相差不大.加固后的现场试验表明,该桥的竖向刚度提高明显,比加固前提高约50%,桥梁和车辆的动力响应也均满足相关规定,能够保证提速条件下列车运营的安全性、舒适性和平稳性.     

Ship appearance optimal design on RCS reduction using response surface method and genetic algorithms

Radar cross section (RCS) reduction technologies are very important in survivability of the militarynaval vessels. Ship appearance shaping as an effective countermeasure of RCS reduction redirects the scatteredenergy from one angular region of interest in space to another region of little interest. To decrease the scatteringelectromagnetic signals from ship scientifically, optimization methods should be introduced in shaping design.Based on the assumption of the characteristic section design method, mathematical formulations for optimalshaping design were established. Because of the computation-intensive analysis and singularity in shapingoptimization, the response surface method (RSM) combined genetic algorithm (GA) was proposed. The poly-nomial response surface method was adopted in model approximation. Then genetic algorithms were employedto solve the surrogate optimization problem. By comparison RCS of the conventional and the optimal design,the superiority and effectiveness of proposed design methodology were verified.Ky words: radar cross section (RCS); characteristic section design method; response surface method; genetic algorithm (GA) was proposed. The polynomial response surface method was adopted in model approximation. Then genetic algorithms were employed to solve the surrogate optimization problem. By comparison RCS of the conventional and the optimal design, the superiority and effectiveness of proposed design methodology were verified.     

大型潜艇总稳定性计算中出现异常特性的研究

本文通过两个实艇计算对比,阐明大型潜艇在总稳定性计算中会出现异常特性,归纳了异常后的变化规律,指出原有计算公式应作相应的改变。研究指出纵向刚度不足是出现异常的原因,分析了为什么纵向刚度不足会导致异常,确定了异常出现的判据,计算并绘制了异常区域的界限曲线。三个钛合金模型试验验证了异常特性的客观存在。     

马凡综合征9例报告

本文报告了我院1984～1989年收治的9例马凡综合征,其中眼部异常7例,骨骼异常8例,心血管异常8例,3例伴有心绞痛,1例合并感染性心内膜炎,1例尸解证实有主动脉根部血栓形成。并对本综合征的发展经过、预后及治疗作了扼要的讨论。     

接头冲击作用下轨道结构加速度谱分析

本文对实测的钢轨接头处轨道结构加速度进行了谱分析，给出了钢轨、轨枕、道床的加速度功率谱，从频域分析了接头冲击响应，特性，对接冲击的隔离和减振提供了依据。     

高速列车对道碴的动力响应

利用车轮－－轨排－－道碴赤一体的有限元动力模型轨枕作用在道床顶面的荷载谱，进而将该载谱作为道床动力分析的输入，假设道床为尖变问题，分析高速列车以示同道碴厚度的动力响应。计算结果表明，增加道碴厚度能有效地减少小道碴的沉降、速度和加速度、使道床更稳定