Quarter wave plates for submillimeter wavelengths

A review is given of different types of quarter wave plates as presently used in the optical and microwave spectral range, with a view to their application in the sub-mm wave-length range. Two types of quarter wave plates have been constructed and results of measurements at 640m are given.     

小区供水方式经济运行办法的探讨

列举了小区常见的三种供水方式,对各种供水方式的优缺点进行了分析,并着重对水池水泵供水方式进行了阐述,并针对此供水方式提出了四种节能方法,初步探讨了基本原理.     

千禧·龙城住宅小区规划设计

从开发优势条件、规划范围、规划原则、规划理念等方面阐述了千禧·龙城住宅小区的具体规划设计。     

A non-homogeneous boundary-value problem for the Korteweg-de Vries equation in a quarter plane

The Korteweg-de Vries equation was first derived by Boussinesq and Korteweg and de Vries as a model for long-crested small-amplitude long waves propagating on the surface of water. The same partial differential equation has since arisen as a model for unidirectional propagation of waves in a variety of physical systems. In mathematical studies, consideration has been given principally to pure initial-value problems where the wave profile is imagined to be determined everywhere at a given instant of time and the corresponding solution models the further wave motion. The practical, quantitative use of the Korteweg-de Vries equation and its relatives does not always involve the pure initial-value problem. Instead, initial-boundary-value problems often come to the fore. A natural example arises when modeling the effect in a channel of a wave maker mounted at one end, or in modeling near-shore zone motions generated by waves propagating from deep water. Indeed, the initial-boundary-value problem

studied here arises naturally as a model whenever waves determined at an entry point propagate into a patch of a medium for which disturbances are governed approximately by the Korteweg-de Vries equation. The present essay improves upon earlier work on (0.1) by making use of modern methods for the study of nonlinear dispersive wave equations. Speaking technically, local well-posedness is obtained for initial data in the class for \frac34$"> and boundary data in , whereas global well-posedness is shown to hold for when , and for when . In addition, it is shown that the correspondence that associates to initial data and boundary data the unique solution of (0.1) is analytic. This implies, for example, that solutions may be approximated arbitrarily well by solving a finite number of linear problems.

     

城市居住分异的思考

分析了中国城市社区分化的动因，阐述了居住区空间分异现象，探讨了当代中国城市社区分化的现状及问题，提出通过加强居住区的规划管理、房地产的引导控制、社区的建设服务等对居住空间分异加以引导的措施，并揭示出当代中国城市社区变迁的意义和发展趋势。     

智能化小区网站建设的思考与实践

从智能小区建设的角度出发，讨论了网站的基本结构、建站的方式、Web页面的实现技术，分析了智能小区网站规划与设计的一般思路和总体框架，提出了网页制作中一些值得注意的问题。     

面向面内刚性环模型的变参数等效路面模型研究

针对重载车辆行驶过程中轮胎受力大、变形大,传统等效路面模型反映轮胎动态特性作用有限的问题,在定参数等效路面模型的基础上建立变参数串联椭圆凸轮模型,考虑轮胎受力情况对椭圆凸轮形状参数的影响。在MATLAB/Simulink中建立基于面内刚性环轮胎模型的1/4车系统仿真模型,分别对路面和椭圆凸轮进行离散化处理,采取循环迭代的方法同时仿真出等效路形与系统动力学特性。仿真结果表明,在低速行驶时两种模型仿真结果一致;在高速行驶条件下利用变参数等效路面模型计算所得等效路形失去对称结构,更加符合真实轮胎越障状况,为精确的面内刚性环轮胎建模提供方法和理论参考。     

乘法型D/A转换器交流有功功率的测量方法

为了正确反映电力系统的状况,提出了一种高准确度的工频交流有功功率的测量方法.该方法由乘法型D/A转换器构成四象限乘法器,通过理论推导得到了有功功率的理论表达式,分析了测量方法误差及影响测量准确度的因素.对测量误差估计公式的MATLAB仿真表明:有功功率的测量方法误差仅为±0.00370%,远小于国际标准的0.01%.根据该方法,可构造50Hz 工频高准确度的交流有功功率标准表.     

我国夏热冬暖地区居住建筑通风设计现状与思考

合理的居住建筑通风设计不仅可以提高室内空气品质、满足人体的热舒适要求,而且可以降低建筑能耗。本文梳理了近年来我国夏热冬暖地区居住建筑通风设计的研究现状与标准规范,探讨了现有标准规范不全面、技术指标不统一、技术术语内容界定不明确、标准精细化不够、通风设计研究缺失、研究深度不够等方面存在的问题,并提出了相关建议,以期为设计研究与标准规范的完善提供参考。     

银行对抗住房抵押贷款提前还贷的合同设计

本文首先分析了贷款人采用每月等本金还款方式下,贷款人提前还贷行为发生时银行的损失.在这样的背景下设计了银行通过收取违约金对抗住房抵押贷款提前还贷行为的合同,并且给出了违约金收取方案的数学模型.