Parameter estimation using a sensor array in a Ricean fading channel

The estimation of the Direction-Of-Arrival (DOA) and the variance of the angular spread, using an array of sensors in the case of a Ricean channel is considered, using the Maximum-Likelihood, Least-Squares and Weighted Least Squares criteria. The Cramér-Rao bound is also obtained for the problem of interest. Simplification of the cost functions to reduce the dimension of the problem has been carried out and the performance of the methods has been studied based on numerical experiments. A major part of the work was carried out when K V S Hari was visiting the Department of Signals, Sensors and Systems during Jul–Sep 1995, on leave from the Indian Institute of Science     

北京饮用水水源地保护与管理研究

北京市饮用水水源地保护与管理的经验，在于有明确的思路、系统的规划和具体的实践举措．针对北京水源地现状及问题，介绍了北京形成水源地保护与管理的思路、原则和措施。     

Alkylated ureas: mineralization and evaluation as N sources

An incubation experiment was conducted for 11 weeks to study the mineralization of ten alkylated ureas and urea in soil. Six of the alkylated ureas viz. methylurea(MU), 1,3-dimethylurea(1,3DMU), 1,1-dimethylurea(1,1DMU), ethylurea(EU), 1,3-diethylurea(1,3DEU) and butylurea(BU) and urea mineralized during the experiment. Urea mineralized immediately, while alkylated ureas mineralized after an incubation period ranging from less than a week to four weeks (delay period of mineralization). The delay period increased in the following sequence MU < 1,3DMU < EU < BU < 1,1DMU < 1,3DEU, but after the delay period was over the compounds mineralized almost as rapidly as urea. The delay period varied according to the number of carbon atoms in the alkyl group and their position with respect to each other on the molecule. It appeared to be specific for each compound and was apparently not influenced by the presence of urea or other alkylated ureas. This character can be used to develop mixture of various alkylated ureas to obtain N mineralization at the desired time. Rapid evolution of CO₂ and N₂O was observed during the mineralization of urea as well as alkylated ureas. Increase in soil pH was also observed during this period. The simultaneous ocurrence of these events suggested the formation of urea as an intermediate during the mieralization of alkylated ureas. None of the alkylated ureas showed adverse affect on emergence of wheat seedlings and except DEU and BU at high concentration no other alkylated urea showed any adverse effect on initial growth of wheat seedlings.     

具有多重焦点的波带透镜的设计

本文提出了一种新型的具有多重焦点的波带透镜的概念及其设计方法。可提供某些特定的光场分布,而且具有性能稳定、微型化和可实际制作等特点。     

MIMO链路ad hoc网络传输调度算法

针对MIMO链路ad hoc网络中已有传输调度算法未充分利用MIMO空间复用能力的问题,提出了一种新的传输调度算法.该算法通过考虑MIMO的多流接收能力而有效地减小了调度帧长,通过合理安排节点分配顺序使得节点分配的数据流比较平均,同时,该算法通过允许节点发送多个数据流而高效利用了MIMO的空间复用能力.推导分析了传输调度算法的通过量和时延性能,结果表明,与已有算法相比,采用文中算法可以提高网络的通过量,减小网络的平均时延和最大时延.     

多特征自适应融合的粒子滤波跟踪算法

针对跟踪过程中目标形态不断变化或部分遮挡导致鲁棒性差的问题,提出一种基于多特征自适应融合的粒子滤波跟踪算法.该算法从视觉特征集中选取了描述能力强的2种特征,并将其按照与目标模型的多尺度相似度进行线性融合;为了减小跟踪漂移,通过计算当前目标模型与初始目标模型的多尺度相似度自适应地更新目标模型.大量仿真实验结果表明,文中算法可以鲁棒地跟踪到部分遮挡和形态变化的运动目标.     

异类传感器实时信息融合的STMHM算法

异类传感器实时信息融合由于两类设备的数据率不同和数据误差的限制,一直未得到有效解决,提出一种空时二维多假设模型(STMHM)算法来解决该问题。设计的融合数据模型,将异类传感器的测量数据映射在二维直角坐标系下;按照新的融合数据模型分别构建两类传感器的目标量测空间和融合空间;设计量测空间时间初始化方法和目标实体空间的滤波算法;通过仿真验证表明:该算法能够实现异类传感器的信息融合,初次融合成功的确认时间在3～5个主动传感器扫描周期。     

基于两电极体系的水质检测分析平台设计

为实现对水质的多参数检测,设计了一个基于两电极体系的水质检测分析平台。该检测平台通过最小化极化电流的思想,采用辅助电极面积远大于工作电极的电极参数,设计了基于两电极体系的集成电极和软硬件系统,摈弃了传统三电极体系的参比电极,同时克服了传统三电极体系容易污染样品的缺点,能实现电化学工作站的诸多功能。本研究在该检测平台上开展了水样的电导率(EC)、pH和重金属浓度的检测研究,获得了较好的结果,可用于实验室及工业现场的水质监测。     

一种基于多连接属性划分的查询优化算法

查询操作是数据库中最常用的操作,由于分布式数据库的数据分布性和冗余性,使得查询优化处理成为分布式数据库研究的核心问题之一。为了提高分布式数据库查询效率,分析讨论了基于直接连接的常见执行策略和查询优化算法,同时针对分布式数据库应用中多表连接时存在多连接属性,提出一种改进的直接连接查询优化策略。改进后的算法提高了查询执行的并行性,缩短了查询处理时间,提高了查询效率。     

ExtJS框架下表格组件的应用与改进

在油田措施效果评价系统开发中,使用了ASP.NET技术并结合ExtJS框架,设计并实现了一个基于B/S模式的Web应用系统,解决开发中的技术问题,着重对ExtJS中的表格组件进行了改进和扩展,实现了同时显示锁定部分表格列与支持多行表头的复杂表格,对系统中常用的几种表格形态及深入应用作了介绍与分析。