Microstructural topology optimization of structural-acoustic coupled systems for minimizing sound pressure level

The aim of this paper is to present a microstructural topology optimization methodology for the structural-acoustic coupled system. In the structural-acoustic system, the structure is considered to be a thin composite plate composed of periodic uniform microstructures. The discrete design variables are used in the microstructural topology optimization, and the constitutive matrix is interpolated by the power-law scheme at the micro scale. The equivalent macro material properties of the microstructure are computed through the homogenization method. The design objective is to minimize the sound pressure level (SPL) in an interior acoustic medium. The sensitivities of the SPL with respect to design variables are derived. The bi-directional evolutionary structural optimization (BESO) method is extended to solve the structural-acoustic coupled optimization problem to find the optimal material distribution of the microstructure. Numerical examples of a hexahedral box and an automobile passenger compartment are given to demonstrate the efficiency of the presented microstructural topology optimization method.     

模糊系统逼近理论：现状与展望

近年来,各类模糊系统已被证明是万能函数逼 近器,它们能实现任意的非线性连续控制规律和动态模型．本文综述与分析了模糊系统逼近 理论研究的最新成果,并指出了进一步研究工作的方向．     

AutoCAD在机构综合中的应用

利用计算机辅助设计中的图形处理技术,实现常用机构的图解法综合。作图求解精度可达到解析法的求解精度。用于解决机械原理多媒体辅助教学软件中有关机构综合问题,取得了明显的效果。     

高级在轨系统下行链路控制器的设计与实现

在对AOS系统进行功能模块划分的基础上,介绍了系统中一个非常关键的组成部分下行链路控制器.该方案采用我国自主知识产权的核心器件--方舟系列CPU芯片,在Linux操作系统下设计与实现下行链路控制器,并给出了其主要的工作流程.试验结果表明该下行链路控制器较好地实现了多路数据的包装与复用.     

C语言程序教学的问卷调查分析与教学改革

C语言程序是学习和掌握计算机技术的基础课程,如何改革该课程教学,提高教学质量,一直是人们所关注与探讨的问题。本文从对学生的问卷调查结果的分析入手,总结、剖析了我院的C语言程序课堂教学中存在的问题,并结合实际提出的一些建议,以期对教学改革有所意义。     

利用客户端脚本实现复合查询的新思路

本文主要针对目前网站上常用的查询系统所存在的某些常见问题而提出了一种新的查询设计思路,这种新的设计思路主要是在客户端利用JavaScript脚本语言对用户设置的查询条件进行预处理,让用户设置的条件以两种形式出现在系统中,一种形式方便方便用户阅读和理解,另一种形式用于真正的数据查询;此外,通过脚本语言将用户设置的查询条件保存于页面上列表中,用户可以随意组合现有的条件形成更为复杂的查询条件;同时用户也可以在列表中随意选择某个条件执行数据查询。     

Three-dimensional reconstruction on PC-Windows platform for evaluation of living donor nephrectomy

Evaluation of renal vasculature was necessary for preoperative donor assessment in living donor kidney transplantation, and the ability to view the vascular imaging in three-dimensional (3D) space should be helpful undoubtedly. Considering the widespread use of personal computer (PC) systems, we aimed to find a handy way to display the anatomy of the renal arterial and venous systems of potential donors on PC-Windows platform. Ten living-related donors were included in this study. Serial computed tomography (CT) images were loaded into Amira 3.1 running on a PC with Windows XP. Following image crop, segmentation and 3D reconstruction, we got the 3D images and the video clips. According to the displays which were confirmed by latter intraoperative findings, eight donors had single renal vessels, one had a left accessory renal artery and one had a right accessory renal artery. This project offered a new approach to evaluate the renal vessel anatomy in living donor kidney transplantation, and it was favorable for accuracy and popularizing.     

《化学反应工程》多媒体课件的开发及应用

本文介绍用VB语言开发《化学反应工程》多媒体课件的性能特点,讨论实现中的一些主要技术及课件的使用情况。     

电子商务对税收的影响和对策研究

电子商务在全球范围内发展迅速,对现有经济运行与管理模式产生了极大的冲击,尤其是引发了许多 税收征管方面的问题。使得有关国际税收的一些概念需要重新界定;网上交易下的国际税收问题加剧, 导致政府税收大量流失;征管和稽查难度加大,对各国的税收协调提出更高要求。提出了对付网上交易涉税问题的对策。     

测定外延层电阻率的面接触方法研究

评论了美国科学家C.C. Allen等于1966年发表的“测定外延层电阻率的点接触方法”之论文的局限性,从而提出了本方法。本方法从理论上解一维Poisson方程并与C.C。Allen法的公式相比较,获得某些公式。文中导出了面接触方法雪崩击穿电压V_(Ba)~∞(V)及点接触方法雪崩击穿电压V_(Bp)~∞(V)的比值为V_(Ba)~∞=0.456;同时还导出了点接触方法外延层耗尽层宽度为t_(min p)(μm)和面接触方法外延层耗尽层宽度t_(mina(μm)的比值为t_(minp)/t_(mina)=2.565。在实践上,为证实两种模型的功能,利用两种探针进行了对比测试。一种是通常被采用的点接触锇尖探针:另一种是利用φ0.8±0.1mm的银针,在银针顶上吸上φ0.4±0.1mm的汞球,以实现面接触。理论和实验吻合良好。