读者信箱

穷则思，思则变，变则通。两门也好，四门也罢，作祟的无非是市场，那我们不妨听听来自消费者的声音。     

伪越野爱好者的“自由”

2008年4月中旬卖掉陪伴我们5年的起亚千里马,购入起亚城市SUV狮跑2.0GLS自动版。同事和朋友不解,说你们怎么成了韩国车的拥趸了?其实也不难理解。物质决定意识,能够买什么车,不是     

玩修品改车

老师您好，我的车是翼神2011款2．0顶配型，想改装一下外观，有几个问题想请教一下，预算在10000块左右（包围带轮毂）。     

微变异

宝马在早年推出的5GT已经引起了一阵流言蜚语，更颤覆了人们对GT的印象，现在这样的“创新传统”落到了3系身上，变异成3GT。     

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.     

机车车辆等效(二次换算)闸瓦力的速度分级核定

等效（二次等效换算）法对于多种材质闸瓦（片）并用的列车制动力计算甚为适用,但是很多闸瓦的等效系数受到制动初速度的影响,所以按列车最高速度的3个级别,分别对应选择各种闸瓦（片）的等效系数以及确定相关的机车车辆每台（辆）的等效闸瓦力符合列车运用状况,更接近实际。这3个速度级别是对应（1）160 km/h快速客车（含快速客运机车、快速动车组及快速行邮车）;（2）120 km/h普通客车（含普通客运机车、普通行邮车和行包车以及快运货运机车和快运货车）;（3）100 km/h普通货车（含普通货运机车）。此外,还核定按湿轨黏着条件限制的机车车辆不同闸瓦（片）的比换算闸瓦力以供铁道机车车辆制动设计及运用参考。     

法国大面包：雪铁龙大C4毕加索

一辆既可以商用又可以家用的MPV,外观设计前卫而且非常有特点,面对这样一辆前卫车型,编辑部内又开始了新的争论。     

圆形坑道的精确弹性解

本文按弹性理论和应力释放法概念，用一个简单的应力函数求出了圆形坑道的精确弹性解，舍弃了近似解中以坑道中心初始应力替代周边初始应力的假定，使计算结果更接近实际，本文推导的公式可用以检算弹性介质中圆形坑道的稳定性，并可作为检验数值分析精度的依据。