A Digitally Controlled Stimulator for Neurophysiological Applications

A stimulator circuit is presented which is capable of generating pulse train waveforms suitable for neurophysiological experiments are available, as well as special test conditions such as dishabituation. Digital and linear integrated circuits are used to provide precise control over the stimulus parameters.     

基于DPCA的双通道SAR动目标检测研究

文中首先分析了基于相位中心偏置天线(DPCA)技术的SAR动目标检测原理,然后详细介绍了基于该原理建立的一种新的双天线动目标检测模型。该模型能在检测出动目标的同时精确估计出动目标的运动参数。最后通过将真实的雷达图像和模拟运动点目标合成的数据,验证了模型的正确性和有效性。此模型易于实现,运算量小,适合运用于现代雷达系统。     

220MW汽轮机DEH系统挂闸异常现象的分析及对策

2004年#2机组大修后启动过程中,出现了汽轮机挂闸后随即打闸的异常现象。通过观察、分析、试验,确定了造成挂闸异常的原因并提出了解决问题的办法,克服了汽轮机挂闸后自动打闸的现象。     

Terahertz Semiconductor Quantum Well Devices

For eventually providing terahertz science with compact and convenient devices,terahertz (1～10THz) quantum-well photodetectors and quantum-cascade lasers are investigated. The design and projected detector performance are presented together with experimental results for several test devices,all working at photon energies below and around optical phonons. Background limited infrared performance (BLIP) operations are observed for all samples (three in total) ,designed for different wavelengths. BLIP temperatures of 17,13, and 12K are achieved for peak detection frequencies of 9.7THz(31μm) ,5.4THz(56μm) ,and 3.2THz(93μm) ,respectively. A set of THz quantum-cascade lasers with identical device parameters except for doping concentration is studied. The δ-doping density for each period varies from 3.2 × 1010 to 4. 8 × 1010cm-2. We observe that the lasing threshold current density increases monotonically with doping concentration. Moreover, the measurements for devices with different cavity lengths provide evidence that the free carrier absorption causes the waveguide loss also to increase monotonically. Interestingly the observed maximum lasing temperature is best at a doping density of 3.6 × 1010cm-2.     

龙芯2号配套PCI Bridge的功能覆盖率验证

介绍了龙芯2号配套北桥中PCI Bridge的功能验证系统以及功能覆盖率建模和分析方法。该系统和方法在开发和验证PCI Bridge模块过程中发挥了重要作用，加快了PCI Bridge的开发速度，协助发现了一些设计与规范不相符合的地方，对后期流片成功提供了有效保证。描述的功能覆盖率建模和分析方法具有一定通用性，可以为其它相似系统的验证提供借鉴。     

南黄海辐射沙洲附近海域悬浮泥沙的遥感反演研究

利用2003年实测的悬浮体样品和遥感反射率数据以及美国NOAA气象卫星AVHRR数据的可见光波段,进行了南黄海辐射沙洲附近海域悬浮泥沙的遥感反演研究.结果发现:悬沙浓度和实测遥感反射率之间存在很好的线性关系(R2=0.9537, n=39),利用该关系式进行该区悬沙遥感反演取得了较好的结果.遥感反演证明,研究区悬沙浓度值由高至低从沙洲中部向沙洲周围延伸;悬沙的分布呈现出明显的季节性,秋季悬沙浓度值一般为春季的1/5;且秋季悬沙的平面扩散范围要小于春季的扩散范围.以上研究结果可为我国海岸带泥沙实时监测和悬浮泥沙遥感定量研究提供必要的基础资料.     

基于网络的分布式水质监控系统设计

结合我国水质监测工作的现状,提出了一种基于网络的水质在线监测系统的设计方案,开发出具有三层网络架构的水质在线监控系统。该系统以LabVIEW为测控平台,具有Web化功能,使得基于网络的远程水质在线监测成为了可能。     

远程电能表监测系统的设计与实现

介绍了一个远程电能表监测系统的3个子系统:服务器端系统、通信网络系统以及下位机系统。通过监测系统的用户交互界面、远程电能表监测操作、通讯控制、数据库管理等多项功能模块的协调合作,可以实现电能表的远程监测以及电能表数据库管理等功能,能很好地满足远程电能表监测系统的各种工程需求。     

油温控制阀的特性分析

对油温控制制阀的机械原理及其传热传质机理进行了理论上的探讨，为油代的试验研究提供了理论依据。     

A Conjecture on Wiener Indices in Combinatorial Chemistry

Drugs and other chemical compounds are often modeled as polygonal shapes, where each vertex represents an atom of the molecule, and covalent bonds between atoms are represented by edges between the corresponding vertices. This polygonal shape derived from a chemical compound is often called its molecular graph, and can be a path, a tree, or in general a graph. An indicator defined over this molecular graph, the Wiener index, has been shown to be strongly correlated to various chemical properties of the compound. The Wiener index conjecture for trees states that for any integer n (except for a finite set), one can find a tree with Wiener index n. This conjecture has been open for quite some time, and many authors have presented incremental progress on this problem. In this paper we present further progress towards proving this conjecture—through the design of efficient algorithms, we show that enumerating all possible trees to verify this conjecture (as done by all the previous approaches) is not necessary, but instead searching in a small special family of trees suffices, thus achieving the first polynomial (in n) time algorithm to verify the conjecture up to integer n. More precisely, we (i) present an infinite family of trees and prove various properties of these trees, (ii) show that a large number of integers, up to at least 10⁸ (compared with the previous best 10⁴) are representable as Wiener indices of trees in this succinct family, (iii) provide several efficient algorithms for computing trees with given Wiener indices, and (iv) implement our algorithms and experimentally show that their performance is asymptotically much better than their theoretical worst-case upper bound.