分布式光纤温度监测系统在选煤厂的应用

针对选煤厂电缆火灾事故的主要原因及特点,提出了一种分布式光纤温度监测系统的设计方案,详细介绍了该系统的工作原理、组成、人机界面、具体功能。实际应用表明,该系统可对电缆夹层、电缆桥架、电气系统等关键区域温度进行实时监控,确保了选煤厂的安全生产。     

一种低电压亚阈值CMOS基准电路的设计

利用负反馈技术设计了一款基于CMOS亚阈值MOS器件的低压高性能CMOS基准源电路。基于SMIC 0.18μm标准CMOS工艺,Cadence Spectre仿真结果表明：所设计的基准电路能在0.8V电压下稳定工作,输出380.4mV的基准电压;在1kHz频率范围内,电源噪声抑制比为-56.5dB;在5℃到140℃范围内,温度系数6.25ppm/℃。     

Welding current and arc voltage control in a GMAW process using ARMarkov based MPC

A predictive functional controller based on ARMarkov model structure has been designed to control welding current and arc voltage in a GMAW process. The closed loop system performance is investigated through computer simulations and is compared by those achieved from implementing two commonly used controllers i.e. PI and feedback linearization based PID. The local stability of the closed loop system is analyzed in the presence of uncertainties in the linearized model of the process as well as the control parameters. Finally it is shown that the proposed controller performs like a PI controller along with a pre-filter compensator.     

基于感应无线的高分辨率位置检测系统研究

为了提高移动机车位置检测精度,提出了一种感应无线位置的检测方法.该方法采用一条独特的编码电缆,利用电磁感应原理,建立了发送线圈与编码电缆之间的信息传输系统,并通过检测感应电动势的相位和幅度,得到移动机车的位置.分析了感应无线检测的原理和方法,推导出了位置检测公式,并进行相关试验.试验结果表明,感应无线位置检测分辨率为2mm,检测精度达到了国际先进水平,可广泛应用于移动机车自动定位中.     

基于MIP的WiMax终端退网研究

针对WiMax网络架构标准中CMIP下的终端异常退网问题,介绍WiMax标准的体系架构及移动IP协议,研究现有CMIP/PMIP模式下终端的退网和资源释放情况,在此基础上,设计并实现一种新的解决方案,将检测终端异常退网和发起终端退网流程的决策权交给接入网关。对其进行测试,结果表明,该方案既可解决CMIP模式下终端异常退网时不能及时进行资源释放以及用户计费等问题,也适合终端正常退网和PMIP模式下的异常退网等情形。     

BIOS木马机理分析与防护

针对嵌入在计算机底层固件的基本输入输出系统(BIOS)中,木马对计算机系统安全危害巨大、不易删除和不易发现的问题,分析BIOS木马封装结构、植入方法和激活机制,建立BIOS木马特征库和标准BIOS样本库,设计并实现一个BIOS安全检测系统。通过检测系统对计算机BIOS进行安全扫描,能有效防护BIOS木马和未知恶意代码,加强计算机底层固件的安全。     

MEMS AC voltage reference for miniaturized instrumentation and metrology

This work explores MEMS (Micro-Electro-Mechanical Systems) potentialities to fabricate AC voltage references through mechanical-electrical transduction that could be used for high precision electrical metrology and for applications in miniaturized instrumentation. AC voltage reference ranging from 5 V to 90 V have been designed and fabricated using the same Epitaxial Silicon On Insulator (SOI) surface micromachining process allowing an accurate control of both dimensions and material properties. The measured MEMS AC voltage reference values have been found in a good agreement with CoventorWare calculations. These tests structures have also been used to develop the read-out electronics to drive the MEMS.     

Effect of aspect ratio on convection in a porous enclosure with partially active thermal walls

The aim of the present numerical investigation is to understand the effect of aspect ratio and partially thermally active zones on convective flow and heat transfer in a rectangular porous enclosure. Five different heating and cooling zones are considered along the vertical walls while the remaining portions of the sidewalls and top and bottom of the enclosure are adiabatic. The Brinkman-Forchheimer extended Darcy model is used in the study. The governing equations are solved by the finite volume method with the SIMPLE algorithm. The computations are carried out for a wide range of parameters and the results are presented graphically. The results reveal that the location of heating and cooling zones has a significant influence on the flow pattern and the corresponding heat transfer in the enclosure. The rate of heat transfer approaches to a constant value for very low values of the Darcy number. The heat transfer rate is decreased on increasing the aspect ratio.     

Enhanced surface plasmon resonance detection of DNA hybridization based on ZnO nanorod arrays

We demonstrated an enhanced surface plasmon resonance detection incorporating ZnO nanorod arrays (NRAs) built on a thin gold film. ZnO NRAs were fabricated by wet chemical growth method and used for the detection of DNA hybridization. Experimental results exhibited that ZnO NRAs provided a notable sensitivity improvement by more than 3 times, which is attributed to an increase in the surface reaction area. The measured sensitivity enhancement matched well with the numerical analyses based on the effective medium theory. Our approach is intended to show the feasibility and extend the applicability of the ZnO-based SPR biosensor to diverse biomolecular binding events.     

基于XML的大宗农产品中远期交易规范研究

为解决不同的大宗农产品中远期交易平台缺乏统一的数据规范、系统共享性与重用性弱的问题,探讨了面向中远期现货交易模式的大宗农产品电子商务数据规范问题,分析了电子交易平台的业务流程,研究了大宗农产品电子商务数据规范方案,并进行了基于XML数据交换技术的实例应用。应用结果表明,基于XML的数据规范适用于电子交易平台的数据共享、传输,使大宗农产品电子交易的数据交换更加便捷。