基于数字锁相放大器的甲烷气体检测仪设计

针对甲烷气体浓度实时检测的要求,设计了一型基于谐波检测原理的检测仪器。该仪器由DFB激光器、准直器、角反射器构成高信噪比光路系统,由数字锁相放大器提取甲烷气体吸收后的一次和二次谐波,并采用标准仪器校准、最小二乘拟合等方法,得到了甲烷气体浓度计算公式,最大测量误差不超过1.1%。测试表明：该仪器通过高性能光路系统和数字电路提取微弱信号,提高了仪器工作稳定性和检测信噪比,测量误差满足使用要求。     

基于TDLAS的时分复用型甲烷多点监测系统

本文设计了一种新型的甲烷多点监测系统,该系统采用分路器将光源出射光分别送至各个气室单元,利用时分复用原理让各气室信号合路传输,然后对解复用后的各路信号进行数据处理,得到待测的浓度信息,实现甲烷浓度的多点实时监控。该系统具有谐波检测技术的优点,且时分复用的引用使得线路的铺设及远程监控更加方便。该系统可实现煤矿等场所的甲烷气体的分布式监测。     

基于单片机的甲烷浓度检测系统设计

以双波长单光路差分检测技术和谐波检测技术为基础,以MSP430单片机为核心控制部件,设计了一个甲烷浓度检测系统,实现了甲烷浓度的实时检测,给出了系统的硬件结构和软件流程图。同时,利用光子晶体光纤和全返直角棱镜优化了气室结构,使气体吸收光程更长,提高了检测系统的灵敏度。     

基于SVM滤波器的吸收式甲烷检测的信号去噪方法

光谱吸收法是对甲烷浓度检测的一种有效手段,通过棱镜气室结合光子晶体光纤的应用实现光谱吸收法对甲烷浓度的高精度在线检测。但在检测过程中,由于环境中温度、压强以及系统本身设备的影响,使得接收的信号中包含大量的噪声。支持向量机(SVM)具有泛化能力强和寻求全局最优点的特点,被用于甲烷浓度检测的信号处理。Matlab实验结果表明,使用SVM原理滤波能有效地滤除噪声,把有效的信号分离出来,并用信噪比评估去噪效果。使用该方法滤波能够使信噪比达到130dB以上,与传统的小波降噪相比有很大的提高,能达到理想的去噪目的。     

基于红外遥控的甲烷气体浓度探测系统

为了解决煤矿坑道口和沼气池等近程的甲烷浓度探测不安全的问题,设计一种用于甲烷浓度探测的红外遥控小车,操纵小车,采用灵敏度可调的气敏元件MQ-2探测目标甲烷浓度,通过单片机和无线收发模块,在手持式终端上显示甲烷浓度。该探测小车具有非接触、响应快、测量精确等优点,方便用于日常生活、工业检测等。     

气体浓度在线检测系统的设计

快速、实时检测甲烷的产生及其浓度,对于工矿安全运行、人身安全、环境保护具有重要的意义.在比尔-朗伯定律的理论基础上,将吸收式光纤传感技术、差分检测技术及计算机数据处理技术相结合,设计了一套高精度的新型时间双光路差分气体浓度在线检测系统,可对气体浓度进行实时在线连续检测.采用计算机的快速数据处理功能,以具有强大软件开发能力的VisualC++6.0为工具,基于用户界面设计出该监测系统的实时动态监控软件.该系统提高了气体浓度检测灵敏度、实现了实时在线连续检测,数据的图形化显示,提高了系统的数据处理能力.     

光纤光栅式甲烷浓度差分检测系统研究

基于甲烷气体的近红外光谱吸收特性,研究了一种全光纤差分吸收式甲烷检测系统.分析了差分吸收检测的基本原理,建立了甲烷检测的数学模型.系统选用发光二极管(LED)作光源,用光纤布拉格光栅进行滤波实现差分吸收检测,并结合光源强度调制技术和锁相放大技术,消除了光路干扰和光源强度波动的影响,提高了测试灵敏度.最后给出了该甲烷气体浓度检测系统的实验结果.     

基于F-P滤波器实现宽谱光源的甲烷差分检测

构建了一种利用F-P滤波器实现甲烷气体差分检测的系统。该系统采用宽谱LED作光源，选用甲烷气体在6060．6cm^-1附近的梳状吸收谱作为探测对象，通过F-P滤波器选择与待测甲烷吸收谱匹配的探测光，对F-P的精细度和腔长进行选择，推导得出了甲烷气体浓度的计算方法，实现了系统的差分吸收检测。该系统进一步提高了气体测量的灵敏度和稳定性。     

基于MCU的智能家居设计系统

文章中智能家居设计系统主要以51单片机为核心,设计了实现语音控制灯和风扇的使用、对环境中气体浓度的检测、温湿度的监测和智能IC门禁卡的功能。开关门和风扇时通过语音控制来实现自动开关门和自动开关风扇,在客厅和卧室需要适宜的温度和湿度,厨房中有毒气体浓度的检测,当检测的数值超过阈值时,通过蓝牙接收信息,将检测结果显示出来并发出提醒警报,如果在时间内没有设定解决,所有电路自动断电,保障家居环境的安全。     

基于单片机的厨房有害气体报警器

本课题研究了一项厨房有害气体检测报警装置,采用STC89C52单片机控制系统,利用气体传感器MQ-5设计气体检测电路、ADC0832模数转换器设计模数转换电路,主要针对天然气,煤气等有害气体实现检测报警功能。通过这些传感器和芯片,检测到厨房有害气体浓度达到对人体有害时,系统会触发报警模块,伴随灯光闪烁和蜂鸣器提示,以此来提醒人们做出措施。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.