Because of its very low light extraction efficiency(LEE),LED is limited to be widely used under the condition of the internal quantum efficiency which up to 90%.In order to fullfill the design of a more efficient GaN-based blue light LED,the model including deeply etched surface photonic crystals(PhCs)LED is discussed using mode analysis method from light waveguide theory.The distributions of all order modes in GaN layer are obtained by the effective index approximation.The light extraction efficiencies are also calculated by finite-difference time-domain method(FDTD).The emulated results fully coincide with the former analysis.Because the manufacture of the surface photonic crystal is feasible,the work can be very meaningful to design and manufacture the high efficiency GaN-based blue light LED in factory for a large amount.
This paper presents the application of an effective electroencephalogram(EEG)based brain-computer interface(BCI)for controlling a remote car in a practical environment.The BCI uses the motor imaginary to translate the subject’s motor intention into a control signal through classifying EEG patterns of different imaginary tasks.The system is composed of a remote car,a digital signal processor and a wireless data transfer module.The performance of the BCI was found to be robust to distract motor imaginary in the remote car controlling and need a short training time.The experimental results indicate that the successful ternary-control by using motor imaginry may be practicable in an uncontrolled environment.
In this paper,potential use of perfect but delayed channel estimates for variable-power discrete-rate adaptive modulation is explored.Research is concentrated on block by block adaptation.At first,a new quantity-TAUD(Tolerable Average Use Delay)is defined,it quantifies the performance of an adaptation scheme in tolerating the delay of channel estimates.Then,the research on TAUD shows that the delay tolerating performance declines with the increase in average power,the scheme working with more modulation modes can tolerate a longer delay,and such improvement will be more significant with the increase of average power.Finally,it shows that,as the delay tolerating performance determines the maximum block length,it has a great effect on the maximum spectral efficiency.The criterion for determining the block length appropriate for the target BER is described and a simple method of calculating the maximum block length is presented.
针对企业生产设备的巡检工作中存在人为的错巡、漏巡等问题,设计实现了一种基于GPS和RFID技术的智能巡检系统。该系统以计算机为依托构建中央信息处理系统CIPS(Central Information Processing System),以PocketPC作为巡检终端PS(Portable Station),采用SQL Server 2000关系型数据库和SQL Server CE3.0嵌入式数据库技术,集RFID技术、GPS定位技术、信息管理、信息传输等多项技术于一体,完成信息在CIPS和PS之间的交互,实现巡检信息的综合处理。
针对许厂煤矿井下经常出现供水短缺或供水过量的情况,设计了一套基于MCGS(监视与控制通用系统,Moni-tor and Control System)和S7-200PLC的自动控制供水调节与监控系统,该系统采用MCGS作为组态软件,S7-200PLC作为核心CPU进行设计,经在许厂煤矿现场实践,该系统能根据管路上水压的大小实时地调节水阀的开度,使水管上的水压保持恒定,并能利用井下工业以太网通信技术实现井下整个供水和供风管网的远程实时监控。
