新型在线近红外分析系统用于工业醋酸生产的实时监测

醋酸生产过程的实时在线监控一直是困扰醋酸生产安全和质量控制的关键技术难题。传统的在线色谱分析方法由于其固有的缺点无法满足实时在线监测要求。以SupNIR-4510在线近红外分析仪为核心,设计实现的新型在线近红外分析系统可现场在线分析醋酸反应釜中各组分含量的实时变化,该系统可实现实时在线分析。实验室模型和现场试用均证实该系统稳定性好、准确性高,较好地解决了醋酸安全、稳定生产的关键技术难题。     

危化品运输跟踪监测系统上位机的设计与实现*

针对危险化学品的特殊运输环境和事故风险,设计了一种基于卫星通讯系统的危险化学品运输跟踪监测系统,并结合百度在线地图和C#、JavaScript语言实现了上位机端的远程监控,重点介绍了远程监测中心的数据通讯方式、GIS可视化、运输状态监控的实现。终端检测到的信号通过GSM短信或TCP/IP方式反馈至监控中心,由监控中心上位机对数据进行自动处理和图形化显示,并对危险情况进行预警。经过测试和分析,系统的操作界面简洁直观,检测精度满足运输需求,能有效提高运输过程中的安全性。     

分布式矿井粉尘浓度在线监控系统

为解决矿井中粉尘浓度测量精度低和在线监测难的问题,利用电荷感应原理设计了高精度矿井粉尘浓度传感器,使输出的感应电流与粉尘浓度之间建立了良好的线性关系;采用三级管理结构设计了分布式矿井粉尘浓度在线监控系统,系统主要由粉尘监测节点、风机控制器、数据汇聚基站、监控中心和传输网络组成;粉尘监测节点与数据汇聚基站通过ZigBee网络组成星型结构,定时采集周围环境中的粉尘浓度信息,并发送给数据汇聚基站;数据汇聚基站与监控中心采用C/S架构设计,将接收到的各监测节点数据打包后,通过局域网实时发送到监控中心的服务器上;监控中心接收、处理、分析和显示从各终端发来的数据,并将存入数据库ACCESS2003中;当某区域出现粉尘浓度过高时,会自动发出报警信号,并控制对应的风机加大排风量,使粉尘浓度保持在安全范围;通过测试实验结果表明,设计的粉尘浓度传感器具有较高的测量精度,平均误差仅为2.95%,且粉尘浓度在线监控系统工作稳定可靠。     

近红外光谱与多元统计方法用于生产过程实时分析

近红外漫反射光谱快速、无损且适用于实际复杂样品分析等特点被广泛应用于在位和在线分析。基于近红外光谱漫反射技术和多元统计过程分析方法建立了一种适用于生产过程分析与在线实时监测新方法。该方法实时采集生产过程中物料的近红外光谱,并利用已建立的模型计算统计量Hotelling T2对生产过程进行实时评价。模型的建立采用了主成分分析,统计量根据实时光谱在主成分模型上投影进行计算。实际应用表明,利用该方法可以根据统计量实时监测生产过程中物料的变动情况,并根据不同批次统计量的进一步统计实现批次间的相对稳定性分析。因此,该方法可作为生产过程质量控制的良好手段。     

基于GPRS的下水道气体远程监测系统设计

为了提高城市下水道气体监测的实时性和可靠性,本文设计了基于GPRS的下水道气体远程监测系统。该系统主要包括前端气体采集模块、GPRS数据无线传输模块、数据接收模块及监控中心;气体采集模块由气体传感器和数据采集单片机组成;单片机实时采集气体传感器中的数据,并将采集到的数据通过GPRS无线传输模块进行实时上传;数据接收模块把接收到的数据传送至监控中心服务器,由服务器对数据进行处理、显示、存储和统计等。通过对18个监测点的监测实验效果表明,该系统运行稳定可靠,能实现对下水道气体远程采集、无线传输和实时监测的目的。     

基于web网络优化协议的水质污染程度在线监测系统设计

针对传统人工水质污染程度检测工作效率低、实时监测能力不强的问题,设计并实现了基于web网络优化协议的实时在线水质污染程度自动监测系统,系统利用无线传感器网络节点对区域水源水质进行监测,通过无线分组通信技术与宽带网络对数据进行远程传送,工作人员可实现web实时在线的水质信息查询、管理控制、数据收集、报警提示等操作,基于web的水质监测系统,提升了系统的可扩展性、易用性以及实时性等;系统硬件包括传感器模块、无线通信模块、单片机外围电路、以太网接口模块等;系统软件设计了web网络优化协议、系统监测平台、远程参数设置、驱动程序等内容;应用该系统对西安市护城河的水质进行污染程度监测,部署20个传感器监测节点,1个监测子站节点,1个远程web监测主站,分别监测河水中pH值、总磷浓度TP、化学耗氧量(COD)、氨氮浓度,连续采样两天时间,通过仿真实验表明,该系统实现了100%的通信成功率,网络之间访问速度是传统网络协议的5~8倍,无线传感器网络与远程监测工作稳定可靠,通信速率满足实时监测要求,适用于对城市水源水质污染程度的实时在线监测。     

用于特殊对象监测的电子传感器平台

特殊对象一般指涉及国家利益和公众安全的特别目标。国际安全反恐和防扩散领域的一个重要概念是特殊对象的连续监测(constant monitoring)，特别是特殊对象在运输过程中的全程、实时、不间断的监测。普通传感器不能满足特殊对象监测的特殊需求，因此必须研究特别的电子传感器平台(electronic sensor platforms，ESP)用来测量特殊对象及装载容器的各项参数，并按一定时间间隔将数据传回监控中心。     

基于虚拟仪器的核电站主管道振动监测系统设计

针对主管道振动在线监测的迫切性需要,分析了主管道振动监测的原理;开展了核电站主管道振动监测系统的硬件设计和软件设计;采用LabView为开发平台,集虚拟仪器技术、设备组态图形技术和数据库管理技术于一体,实现了主管道振动的在线实时监测;利用电磁振动台模拟主管道的振动,验证了主管道振动监测系统的性能和基本功能。     

基于ZigBee与CAN的工程机械液压系统参数监测系统设计

为了实现工程机械液压系统相关参数无线、有线、远程实时监控,设计一种基于ZigBee和CAN总线的工程机械液压系统参数监测系统。该液压监控系统由现场数据采集节点,无线与有线通信模块及计算机监控中心组成;数据采集以英飞凌XC2267芯片为核心,通过传感器对液压抓斗的液压油油温、压强、液位等信号进行采集,利用ZigBee无线传感器网络与CAN 总线将采集的参数送给监控中心;如果工作参数异常,监控中心可以提醒现场操作人员进行预警。     

基于嵌入式linux的杆塔倾斜度在线监测仪设计

为保障电网的安全稳定运行,减少因杆塔倾斜引起的停电事故,需要对杆塔的状态进行实时监测。设计开发了一种杆塔倾斜度在线监测装置。建立了杆塔倾斜度监测模型,根据重力加速度测量值计算倾斜角的原理,采用SCA100T-D01双轴倾角传感器进行数据采集,采用基于arm9的嵌入式linux系统进行数据的存储和计算,并通过以太网或GPRS网络传送数据,实现了对杆塔倾斜各状态量的在线监测。详述了该装置各个模块的软件设计。该装置支持配置不同地区的重力加速度,提高了测量精度;支持自动配置初始安装角度,大大提高了输电线路生产管理水平。详述了自动配置的规范,经工程实践,该装置在输电线路杆塔倾斜度的监测上取得了良好应用。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.