矩形波导缝隙阵列天线的快速综合算法

矩形波导缝隙阵列天线计算复杂,本文提出一种快速综合算法,充分考虑互耦的影响,并且可以对同相或不同相缝隙电压加权进行综合.首先在有源导纳法的基础上得出一个矩阵方程,互耦的影响和缝隙自身的影响分别可以用方程中的一个矩阵完全表示.分析矩阵的特性后,本文可将对面阵的综合转换为对每条波导上缝隙的综合,大大降低计算量.仿真实例验证了算法的有效性.     

具有平均流的消声器声学特性的改进体积合成算法分析

在阐述了体积合成算法基本原理的基础上,对其进行改进,使其适用于存在平均流的消声器声学特性的预测.使用改进后的算法对一些不同结构类型消声器的传递损失进行预测,并通过与有关文献和实验数据的对比进行验证.最后以一个实例讨论了平均流对消声器声学性能的影响.     

城市轨道交通车站大客流应急疏散研究

城市轨道交通日益重要的地位和密集人群事故的频繁发生,促使人们更加关注车站大客流突发事件.根据车站的建筑结构特征和客流特征,采用计算机模拟大客流突发事件下的应急疏散过程,解决了实际中无法模拟的疏散过程,同时能够及时发现特定结构下的疏散死角,有效提高客流疏散效率,节约成本.采用二维结合三维展示疏散过程的方式,使模拟结果更具有实用性和指导性.     

管线综合工程设计工作总结

该文对两个较复杂的管线综合工程通过比较,作出结论,可供相关专业人员参考。     

Type synthesis of function-generating mechanisms for seat suspensions

Mechanisms with “negative” stiffness are a unique tool used to significantly improve vibration isolation for a vehicle driver via upgrade of the seat suspension. However, connection of such mechanisms to the suspension results in errors in the function generation process, and in most cases, makes motion impossible. An approach to type synthesis is presented in order to make this process more predictable, easy and thus more practical for the upgrade process. Structural classification of the suspensions is presented, and -an atlas of function-generating mechanisms for suspensions that reveals the effect of “negative” stiffness is completed. All of the function-generating mechanisms appear in the atlas as result of enumeration. Structural properties of novel and existing mechanisms are compared. Finally, some advantages in practical use of novel suspensions with “negative” stiffness are illustrated.     

斜风作用下风-车-桥非线性分析系统建立

为了从风作用方向的三维模拟和系统非线性2个角度实现风-车-桥系统的全三维高真实度模拟,首先建立斜风荷载处理方法,采用平均风分解理论对桥梁斜风进行分解,形成桥梁斜风荷载,把桥梁风作用方向模拟域由垂直于桥梁纵轴线的二维平面扩展到三维空间;采用矢量合成法则和线性插值方法,依据车辆位置函数确定桥上车辆任意位置和时刻的合成风速,并基于风洞试验获取车辆气动力系数,形成车辆斜风荷载。然后基于已建立的非线性分析系统,融合斜风荷载处理方法,构建斜风作用下的风-车-桥全三维非线性分析系统,并实现动态可视化。最后采用建立的分析系统,对系列风偏角工况下的桥梁空间动力响应和车辆安全进行分析和评价。结果表明：斜风作用下,桥上车辆事故指标值及桥梁位移响应随着风偏角增大总体上均呈现先减小后增大趋势,且极值均出现在非90°的锐角区;基于风向垂直于桥跨方向的假定所进行的桥梁设计和车辆安全性评价结果偏于不安全。     

Modeling transit technology selection in a linear transportation corridor

This paper proposes an analytical model for investigating transit technology selection problem from a perspective of transit authority. Given a transit technology alternative (e.g., metro, light rail transit, or bus rapid transit), the proposed model aims to maximize the social welfare of the transit system by determining the optimal combination of transit line length, number of stations, station location (or spacing), headway, and fare. In the proposed model, the effects of passenger demand elasticity and capacity constraint are explicitly considered. The properties of the model are examined analytically, and a heuristic solution procedure for determining the model solution is presented. By comparing the optimized social welfare for different transit technology alternatives, the optimal transit technology solution can be obtained together with critical population density. On the basis of a simple population growth rate formula, optimal investment timing of a new transit technology can be estimated. The proposed methodology is illustrated in several Chinese cities. Insightful findings are reported on the interrelation among transit technology selection, population density, transit investment cost, and transit line parameter design as well as the comparison between social welfare maximization and profit maximization regimes. Copyright © 2014 John Wiley & Sons, Ltd.     

电铁综合补偿电流实时检测方法研究

有源滤波器是对于非线性负荷电流谐波抑制和无功补偿的重要装置,其中关键的环节就在于其能实时准确地检测谐波和无功电流。本文结合单相负荷谐波、无功电流检测与平衡变压器能够抑制负序条件,提出了2种能够不受左右供电臂负荷限制,能完全动态检测电气化铁道负序、无功与谐波的检测方法,并在MATLAB/SIMULINK下仿真证明该方法可以动态、准确地检测出牵引供电系统负序、谐波及无功电流,并实现三相平衡。     

聚天冬氨酸的合成及应用研究

以马来酸酐和铵盐为原料,成功合成了聚天冬氨酸(PASP),探讨了合成条件对PASP的产率和分子量的影响,确定最佳合成工艺为:铵盐为铵盐A,酐氨用料比为1∶1.2,聚合温度为180℃,聚合时间1 h.并运用红外光谱、差热-热重分析等手段对PASP进行了性质表征,进一步研究了PASP的阻垢、分散、缓蚀等应用性能以及生物降解性能,并对PASP的聚合机理、生物降解机理进行了较详细的讨论.