MIMO系统中简单的扩展空时块编码分集技术研究

本文提出一种多输入多输出（MIMO）天线系统中简单的扩展空时块编码（SSTBC）分集技术，采用沃尔什码来区分各天线发送数据子流。采用这种方法，在系统带宽一定时，不降低发送信息速率，同时接收机简单。不同天线的发送信息经过了所有收一发天线对之间的空间子信道，获得了所有路径的部分空间分集增益，仿真结果表明，这种增益的获得不受限于接收分集阶数，并且随发射天线的增加以一定的线性关系增加。     

Enhanced light output in nitride-based light-emitting diodes by roughening the mesa sidewall

In this letter, we will report on a nitride-based light emitting diode with a mesa sidewall roughening process that increases light output power. The fabricated GaN-based light-emitting diode (LED) wafers were first treated through a photoelectrochemical (PEC) process. The Ga/sub 2/O/sub 3/ layers then formed around the GaN : Si n-type mesa sidewalls and the bottoms mesa etching regions. Selective wet oxidation occurred at the mesa sidewall between the p- and the n-type GaN interface. The light output power of the PEC treated LED was seen to increase by about 82% which was caused by a reduced index reflectance of GaN-Ga/sub 2/O/sub 3/-air layers, by a rough Ga/sub 2/O/sub 3/ surface, by a microroughening of the GaN sidewall surface, and by a selective oxidation step profile of the mesa sidewall that increases the light-extraction efficiency from the mesa sidewall direction. Consequently, this wet PEC treated process is suitable for high powered nitride-based LEDs lighting applications.     

Generalized difference control of parallel streams temperatures

A furnace with multiple parallel passes and multiple burners is commonly seen in petroleum refineries. In order to maintain the furnace running in a safe, stable, and high-efficiency state it is necessary to control the outlet temperatures of the multiple passes to be the same. Due to the fact that the process of the oil heating in such furnace is nonlinear, multivariable, time varying, has serious coupling among passes, has frequent dynamic changes and a large time delay, traditional control methods have trouble in controlling these temperatures, and some advanced control methods, including predictive control, adaptive control, and robust control, are usually too complex for convenient use. In this paper, a control technique, called differences control technique (DsCT), is proposed to distribute the stream flowrates such that the stream temperatures are as identical as possible. The principle of the proposed technique is explained and demonstrated, and the results of its application to a real-life petroleum refinery furnace are also reported. The DsCT technique has the following advantages: it does not need complicated design procedures, the controller structure is simple, it is easy to apply, and it can be canonically applied to furnaces with different number of passes.     

Matlab语言与线性电路的符号仿真

目前的电路仿真软件通常是在电路中所有元件值都是给定的情况下得到一些数值结果，而非解析结果。该文利用Matlab的符号运算功能编程，通过节点列表法，实现了任意线性电路的自动解析求解，为电路分析提供了一个有效的辅助工具。     

清肝明目夏枯草

“夏枯草，味苦辛，性寒，可入肺气郁结所致瘰疬……效果极佳。”但是。在万千而神奇的大自然中，选择夏季这个生命力最为茂盛的季节来结束自己生命的花花草草其实很多。为什么独独夏枯草占了“夏枯”之名？[编者按]     

VS2005—高校实验设备网络化管理的利器

高校实验设备实施网络化管理,能够极大提高设备信息的透明度,提高实验设备管理的效率,进一步优化管理工作.VS2005是开发高校设备管理网站的一种简单易学、功能强大的工具.现给出了一个基本的高校实验设备管理网站开发的全过程.     

高能多脉冲超正压射孔技术

高能多脉冲超正压射孔技术是一项利用高能燃料的燃烧在目的层产生压力的超正压射孔或增产新技术。主要介绍了该技术的基本原理和装置的结构设计，并给出了该技术在国内一些油田的应用实例。实例说明，该技术是一项非常好的完井或增产新技术。     

石蜡微胶囊中脲醛树脂壁材渗透性的研究

利用差示扫描量热法研究了石蜡微胶囊中脲醛树脂壁材对水及甲苯的渗透性 ,结果表明 ,水不能透过脲醛树脂壁材 ,而甲苯则易透过脲醛树脂壁材。因此 ,该石蜡微胶囊不能用于芳香族溶剂存在的场合。     

四川马海毛钢花呢的试制

根据四川马海毛原料资源的品质特性，运用精纺粗做的方法，成功地试制出手感滑糯而富有弹性、光泽明亮悦目，各项物理指标符合FZ/T24002-93标准的四川马海毛纯毛钢花呢，达到了马海毛产品的特殊风格。同时指出四川马海毛制成率偏低。     

Mobile robot path planning based on hierarchical hexagonal decomposition and artificial potential fields

In this article, a new algorithm based on an artificial potential field and hierarchical cell decomposition technique is developed to solve the find-path problem for a mobile robot. The complete map of the workspace including obstacle locations is assumed to be known a priori. The basic cell structure used for decomposition is a hexagon. The artificial potential field is based on an attractive force from the goal position and repelling forces from the obstacles. Computer simulations of the algorithm for various obstacle scenarios are also presented. © 1994 John Wiley & Sons, Inc.