基于FPGA的TDLAS气体测量系统

提出了基于FPGA的气体检测系统,实现了TDLAS气体测量系统小型化、数字化.利用FPGA并行计算、易于实现DDS信号发生和正交数字锁相等特点,可以满足TDLAS测量过程中的高频信号发生、谐波信号的提取等计算,从而采用正交数字锁相方法及拟合法实现气体的测量.将激光器、温度控制模块、电流驱动模块、信号发生器、光电探测器、带通滤波器、ADC采样集成在同一块印制电路板上,实现系统的小型化和集成化.最后,通过在空气中对氧气浓度进行长时监测,验证了本系统的稳定性.     

Pd/PVDF thin film hydrogen sensor system based on photopyroelectric purely-thermal-wave interference

A novel sensitive solid-state sensor system for trace hydrogen gas detection has been developed as a next generation device to earlier photopyroelectric (PPE) hydrogen sensors. The basic principle of the sensor is based on the technique of PPE purely-thermal-wave interferometry recently developed in this Laboratory. The active element of the sensor is a thin polyvinylidene fluoride (PVDF) pyroelectric film, sputter-coated with Pd on one surface and with a Ni–Al alloy electrode on the other surface. Unlike the conventional PPE hydrogen sensors, this new sensor produces a coherent differential PPE signal in a single detector, rather than using two detectors (one active, the other reference) and complicated electronics. The measurement results show that the signal noise level, the detectivity and the signal dynamic range are improved by more than one order of magnitude compared with the conventional single-beam method. The operating characteristics have been examined for three different thicknesses of Pd coating on the same thickness PVDF-film detector. The signal generating mechanism, attributed to the change of the optical absorptance of the Pd coating when exposed to hydrogen, and/or the shift in the Pd work function, is also discussed.     

一种小型化SPR生物传感器的设计与实现

介绍了一种采用不规则四边形棱镜设计的小型化表面等离子体共振(SPR)生物传感器。棱镜结构与已有的TI Spreeta传感器类似,但是在尺寸、光学性能等方面做了较大优化。新研制的SPR传感器在光学检测精度和系统集成性等方面也有了很大提高。在光路设计中,采用波长为630 nm的宽光束红光LED作为光源,5 000像素点线阵CCD作为光电检测器,光学检测效果要大大优于TI Spreeta波长为830 nm的近红外光源和128像素点的线阵硅光二极管。在光路优化的同时,系统集成了流动控制模块、信号采集处理模块,形成了一个可实现生物大分子相互作用分析的集成小型化SPR检测装置。利用空气、水及乙醇等进行的SPR实验表明:该装置能够对单一样本进行精确检测,共振角的检测精度高达0.01°,且检测结果线性度高,稳定性好,单一样本的检测偏差小于0.5%。     

新型高性能智能化离子色谱电导检测系统

结合电子测量技术和计算机智能控制技术，设计了一种新型高性能智能化的离子色谱电导检测系统。系统采用两级分布式控制方式，在有效抑制噪声的同时，能够精确并且智能化的完成离子色谱信号的放大、采集、处理、谱图显示等功能。文章介绍了该系统的硬件组成、软件设计以及系统工作的基本原理，并给出测量实例。实验结果表明系统运行良好，结果可靠，完全可应用于实际的离子色谱检测。     

Poly(dimethylsiloxane)-Based Packaging Technique for Microchip Fluorescence Detection System Applications

A simplified integration process including packaging is presented, which enables the realization of the portable fluorescence detection system. A fluorescence detection microchip system consisting of an integrated p–i–n photodiode, an organic light-emitting diode as the light source, an interference filter, and a microchannel was developed. The on-chip fluorescence detector fabricated by poly(dimethylsiloxane) (PDMS)-based packaging had a thin-film structure. A silicon-based integrated p–i–n photodiode combined with an optical filter removed the background noise, which was produced by an excitation source, on the same substrate. The active area of the finger-type p–i–n photodiode was extended to obtain a higher detection sensitivity of fluorescence. The sensitivity and the limit of detection (LOD;$S/N = 3$) of the system were 0.198 nA/$mu$M and 10$mu$M, respectively. 1710     

Miniaturized flow cytometer with 3D hydrodynamic particle focusing and integrated optical elements applying silicon photodiodes

In this study, the design, realization and measurement results of a novel optofluidic system capable of performing absorbance-based flow cytometric analysis is presented. This miniaturized laboratory platform, fabricated using SU-8 on a silicon substrate, comprises integrated polymer-based waveguides for light guiding and a biconcave cylindrical lens for incident light focusing. The optical structures are detached from the microfluidic sample channel resulting in a significant increase in optical sensitivity. This allows the application of standard solid-state laser and standard silicon-based photodiodes operated by lock-in-amplification resulting in a highly practical and effective detection system. The easy-to-fabricate single-layer microfluidic structure enables independently adjustable 3D hydrodynamic sample focusing to an arbitrary position in the channel. To confirm the fluid dynamics and raytracing simulations and to characterize the system, different sets of microparticles and T-lymphocyte cells (Jurkat cell line) for vital staining were investigated by detecting the extinction (axial light loss) signal. The analytical classification via signal peak height/width demonstrates the high sensitivity and sample discrimination capability of this compact low-cost/low-power microflow cytometer.     

基于虚拟仪器技术的地下水探测系统研究

为了整合磁共振测深(MRS)地下水探测系统的测量与反演功能,结合LabVIEW软件在测量与信号处理方面的优势,利用虚拟仪器技术开发了地下水探测系统的上位机系统软件,实现了对探测系统整个操作流程的管理。根据已知探测地区的拉莫尔频率产生激发信号,送至发射/接收线圈,利用快速关断技术实现了发射与接收的快速切换。将采集的弛豫衰减信号送至反演解释算法模块,采用改进的量子遗传算法与截断奇异值分解(TSVD)的联合方法,反演解释了地下含水层的水文地质参数。野外试验表明,该探测系统的工作稳定性好,验证了反演结果的准确性。     

基于ATMEGA16的便携式瓦斯检测仪

针对目前常用瓦斯检测仪检测范围高时精度低,检测精度高时检测范围低等不足,设计了一种基于双检测回路的便携式瓦斯检测仪。该系统以ATMEGA16控制器为核心,利用催化燃烧式传感器和红外探测器组成双回路瓦斯检测电路,并将朗伯-比尔红外吸收定律运用到瓦斯检测原理中,提高了低瓦斯浓度时的测量精度,同时扩大了瓦斯浓度的测量范围。系统的无线收发模块可以和上位机通信实现信息共享,其开关机电路可以实现关机后仪器与电源完全断开,有效节约电池能量。实验表明该瓦斯浓度检测仪具有检测精度高,检测范围广,高效节能等特点,具有较高的应用价值。     

瓦斯监控系统存在的问题及解决方法

分析了目前瓦斯监控系统存在的问题,指出固定式瓦斯监控系统存在监控盲区且维护不便,而移动式瓦斯监控系统不能联网监测、存在信息孤岛;介绍了一种无线移动瓦斯监控系统,该系统在便携式瓦斯检测仪中加入了无线通信模块,通过分站、无线信号收发器及漏泄电缆实现井下无线信号的连续覆盖,通过在工作面等地点布置一定数量的定位器解决便携式瓦斯检测仪的定点、定位问题。无线移动瓦斯监控系统实现了对便携式瓦斯检测仪的集中、统一管理,以及瓦斯检测数据的实时、自动上传。     

基于漏磁检测的钢管探伤监控系统设计

针对钢管漏磁检测的特殊性,设计开发了一种带有干扰滤波的探伤监控系统,采用信号接收模块配合多串口卡,开辟了多个内存缓冲区,将数据进行多线程并行分析处理,极大地提高了数据处理的速度和检测的实时性。采用均值平移小波阈值去噪法对漏磁检测信号进行降噪处理,有效降低了测量噪音等干扰因素的影响,并消除伪吉布斯现象。软件部分利用 Visual Studio C＃进行开发,可以实现无人值守条件下的全自动流水线检测控制、自动钢管缺陷判断、报警和分析处理等功能。系统具有高的实用性和可靠性。     

基于LabVIEW的天然气水合物电-声联合探测实验装置测控软件开发

天然气水合物模拟实验装置普遍具有测试参数众多、测试过程复杂等特点,必须开发测控软件以满足实验装置对自动化操作的高要求。在分析软件功能需求的基础上,运用软件工程中的模块化、功能化的设计思想,以LabVIEW为平台开发了一套电-声联合探测实验装置的测控软件。该软件包括启动和登录模块、参数设置模块、信号发生模块、多路切换模块、数据采集及处理模块、数据显示及保存模块、错误处理和帮助信息模块。实验测试表明：所开发的测控软件扩展性和可维护性强,人机交互界面简洁直观,自动化程度高,避免了人力耗费过大和人工参与过多对测试结果的不良影响,提高了测试结果的准确性和可靠性以及模拟实验测试的工作效率。     

基于气体传感器的变压器在线DGA系统的研究

设计的在线溶解气体分析（DGA）系统采用高分子膜提取油中溶解气体,利用气体传感器对气体体积分数进行检测,使用无线通信模块将气体体积分数信息传输到主控室的计算机上。与离线色谱相比,在气体体积分数测量范围为（4～200）×10^-6,对H2测量最大绝对误差为2×10^-6,对cO测量在（100～2000）×10“的最大绝对误差为30×10^-6,可以达到对变压器油中溶解气体进行在线监测分析的要求。     

Application of astigmatic method and snell’s law on the thickness and refractive index measurement of a transparent plate

In this study, a thickness and refractive index measuring system for the transparent plate has been proposed. The measuring system is composed of an astigmatic measurement module and a light spot measurement module using a DVD optical pickup, a laser diode and a quadrant photodiode detector. Both of the thickness and refractive index of a transparent plate are converted into the focusing error of DVD pickup based on astigmatic method and the light spot displacements based on snell’s law in our proposed system. The thickness and the refractive index are simultaneously calculated by means of two nonlinear formulas. The accuracy of the proposed system is 99 % verified by a height Gauge and the refractive index by the TF-166.     

Development of an ASIC set for signal processing

An approach to signal acquisition, digitization, and processing of low-frequency physiological signals is discussed. The approach uses a chip attached to a transducer through a digital wire placed at the sensing point. The wire transmits digital information instead of an analog signal to an application-specific integrated circuit (ASIC) signal processor. This digital wire/Visp chip set produces a noise-immune signal processing system usable in a variety of biosignal processing needs. The concept is demonstrated using the Visually Evoked Potential (VEP) measurement system     

基于虚拟仪器的超声信号测量及测距研究

为更好地进行目标探测,利用虚拟仪器技术设计了超声信号测量系统,介绍了系统的构成和各模块工作原理。测距是目标探测的关键技术,重点从信号处理的角度,在分析传统超声射程时间TOF测量算法的基础上,提出了两种基于包络的改进算法,并利用LabVIEW软件来实现。最后利用超声信号测量系统完成超声波信号的采集、存储,回波信号的特征和幅值分析、测距分析等实验,结果表明该系统能对超声信号进行直观信号分析处理,测距准确,为后期目标识别提供了基础平台。     

紫外光谱响应度测量系统设计

由于目前的紫外辐射的定标测量存在测量误差大的缺点,采用热释电探测器作为基准探测器给被测探测器(GaN)进行定标,给出光谱响应度测量系统的设计原理,对高稳定度紫外光源系统、热释电电学定标系统、信号检测电路进行了详细的设计,分析计算机控制和软件处理系统部分功能构成,最后进行了单色仪的波长标定来证明系统的准确性。     

Conception of the optical sensors based on transient processes in MIS structures

New silicon-based optical sensors with metal–insulator–semiconductor structure (MIS) have been developed in this work. The physical properties of these sensors are described with a simple MIS capacitor model. Two-level voltage bias provides a transient between two quasi-equilibrium inversion modes. This transient is applied for storage and readout of the input optical signal for a quantitative measurement of a weak radiation. Proposed simple readout procedure provides reading the integrated information with a significant amplification. The amplification (or the current transformation coefficient) is determined by the ratio of integration and readout times and in this investigation the amplification exceeds the value of 10³. A simple theoretical model is applied to describe the sensor properties at illumination. Numerical calculation under the experimental conditions confirms a validity of the physical model and arguments used at the discussion of the experimental results.     

反射式光纤电流传感的锁相检测法与近似误差

对反射式Sagnac型全光纤电流传感器中光信号的检测方法进行了深入的分析,并对固有的小角近似误差进行了充分的理论分析和数值模拟。针对反射式光纤电流传感器中极其特殊的信号检测要求,采用了锁相检测法来处理传感信号。商用化的光纤电流传感器的误差一般要求小于0.2%,而在各类检测方法的信号处理中,一个必须的步骤是sinθ≈θ,该步骤造成的小角近似误差极大地影响了整个系统的测量精度。通过对这2个问题进行深入的分析与模拟,对解决光纤电流传感器的检测方法设计、测量精度、灵敏度等问题提供了较大的参考价值。     

分布式光纤振动传感信号的采集与处理

以分布式振动传感在周界安防中的应用为研究对象,简述了一个全光纤扰动传感与定位系统。分布式光纤传感与定位系统主要由光发射模块,传感光路模块,光接收模块,信号采集模块,信号传输模块及信号处理模块构成。振动信号的采集与处理决定着系统报警及定位的实时性和准确性,主要研制了振动传感系统中的数据采集与处理系统。