基于波磨磨耗定量的地铁小半径曲线轮轨仿真

针对地铁小半径曲线上普遍存在的钢轨波磨问题,基于轮轨间粘滑振动导致波磨形成的机理,利用MATLAB/Simulink建立了一个集轮轨耦合动力学、轮轨滚动接触力学模型以及Archard材料磨损模型为一体的单轮对轮轨曲线通过仿真模型进行研究。仿真结果表明,曲线半径越大,钢轨波浪型磨耗越不易产生。该结果与实际小半径曲线上波磨频发相符合,证明了该模型的正确性。最后,利用该模型进一步分析了车辆载重与曲线超高对波磨的影响。     

雷达罩瞄准误差测量不确定度评定方法研究

雷达罩电性能测试系统是一种复杂的计量器具,需要对其检测结果的不确定度进行评定,以前在这方面几乎没有开展工作。以雷达罩电子定标法为例,对影响瞄准误差测试结果的主要因素进行了分析,确定了不确定度分量。采用A 类或B 类评定方法,对每个分量的标准不确定度进行了分析计算。研究了不确定度分量之间的相关性,并对合成标准不确定度和扩展不确定度进行了计算。该方法也可用于雷达罩传输效率、方向图畸变和功率反射等电性能参数测量不确定度的评定。     

Electrochromic Detection of Latent Fingermarks on Metal Surface Using 1,1′-Dibenzyl-4,4′-bipyridinium Dichloride

The electrochromic detection of latent fingermarks on polished or unpolished, flat or curved metal surfaces is described using electrochromic material, 1,1’-dibenzyl-4,4’-bipyridinium dichloride. The surface area covered by fingermarks acts as an insulating mask, causing 1,1’-dibenzyl-4,4’-bipyridinium dichloride to change color and produce inversed images of the fingermark. By changing the applied potential, the optical properties of 1,1’-dibenzyl-4,4’-bipyridinium dichloride can be continuously and reversibly adjusted to optimize the visual contrast of fingermarks, so as to realize the detection of latent fingermarks on stainless steel surface. It is demonstrated that the fabricated electrochromic devices can detect the fingermarks on these types of surfaces within twenty seconds at −1.0∼−2.0 V. This work can qualify as a tangible improvement in fingermark detection of the natural fingermarks on the never-cleaned (more than 3 years) and curved surfaces of daily-used container, e. g. cup, and the handle of cleaning tool, mop.     

天线-罩系统的散射计算

应用物理光学法(PO)对天线-罩系统的散射特性进行分析。通过对罩壁的局部平板等效,导出了天线表面的感应电流和罩表面的等效电、磁流分布的计算公式。以口径天线-多层介质结构雷达罩为例,计算了天线、雷达罩及天线-罩系统的单、双站雷达散射截面(RCS),并研究了当照射波频率和天线扫描角变化时RCS的变化规律。     

Incompatible curved quadrilateral plate bending element with 12-degrees of freedom

This paper presents a new curved quadrilateral plate element with12-degree freedom by the exact element method.The method can be used to arbitrary non-positive and positive definite partial differential equations without variation principle.Using this method,the compatibility conditions between element can be treated very easily,if displacements and stress resultants are continuous at nodes between elements.The displacements and stress resultants obtained by the present method can converge to exact solution and have the second order convergence speed.Numerical examples are given at the end of this paper,which show the excellent precision and efficiency of the new element.     

A calculation method for fully developed flows in curved rectangular tubes

I.IntroductionacestudyofviscousnowincurvedtubesisoffundamentalinterestinfluidmechanicssincetheDean'spioneerwork(1928)l']oncurvedpipes.Therearenumerousapplications,whichincludetheflowsthroughturbomachinery,aircraftintakes,diffusersandheatexchangersetc.Itwa…     

充分发展管流计算中的一种方法

本文结合摄动法、伽辽金法和有限差分法求解小曲率及小Dean数情形下充分发展的弯曲矩形管中的二次流流函数ψ、轴向速度w,该方法避免了直接求解N－S方程的巨大工作量,也克服了通常流函数法中构造高阶差分的困难.小曲率、小Dean数情形针对不同宽高比的计算结果与前人的计算与实验结果对比表明,该方法是成功的.     

多频段天线罩功率传输系数的优化设计

按射线跟踪法分析天线罩的理论,把罩壁近似为均匀多层介质平板,对其传输特性进行了分析;根据天线罩须在多个频率段上有较高传输系统的特殊要求,按最大最小原则建立了二重优化模型,采用ＳＵＭＴ外点法和ＰＯＷＥＬＬ法相结合对天线罩的各层介质壁厚进行优化设计;对某型２０／３０ＧＨｚ双频段卫星通信天线罩的优化达到了预期效果。     

弹性支承圆弧梁内力分析

以现代桥梁及房屋结构为工程背景,提出弹性支承曲线梁计算模型,按结构力学方法推导出弹性支承圆弧梁的内力计算公式,分析讨论了竖向和抗扭弹性支承对内力的影响．     

The perturbation parameter in the problem of large deflection of clamped circular plates

In the problems of large deflection of clamped circular plates under uniformly distributed loads, various perturbation parameters relating to load, deflection, slope of deflection, membrane force, etc, are studied. For a general perturbation parameter, the variational principle is used for the solution of such a problem. The applicable range of these perturbation parameters are studied in detail. In the case of uniformly loaded plate, perturbation parameter relating to central deflection seems to be the best among all others. The method of determination of perturbation solution by means of variational principle can be used to treat a variety of problems, including the large deflection problems under combine loads. This paper is completed under the guidance of Prof. Chien Wei-zang.