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Design Of Multiplegas Sensing Systemsbased On Optical-fiber Network

Posted on:2018-12-12Degree:MasterType:Thesis
Country:ChinaCandidate:W YangFull Text:PDF
GTID:2428330566951517Subject:Software engineering
Abstract/Summary:PDF Full Text Request
With the growth of the population and the development of industry,gas detection system takes increasing attention.For example,in the coal mine,the ore miner's life safety closely relates to the concentration of methane,carbon dioxide and other gases,so the real-time detection of gas concentration becomes significant.Besides,the growth of the poisonous and harmful gas emissionby vehicles,industry and agriculturehas causedenvironmental degradation,and gas detection also plays an important role in environmental protection.With the continuous development of gas detection technology,gas detection method is also in constant innovation,such as electronic sensor technology which has beenrelatively matureand widely used.Thecommercial productsare also verypopular in the market.Nevertheless,traditional gassensors aresomewhat limited by electromagnetic interference,discretedistribution,cross interference and high network costs.In recent years,the development of photoelectric gas detection technology has been greatly promoted and investigated.Optical fiber gas sensinghasmany advantages,such asthe intrinsicsafety,long working life,immunityto electromagnetic interference.Besides,it couldreduce the cost for a wide range and long haulsensingnetwork construction.This paper proposes and demonstrates two typesof gas sensing network systems based on optical fiber sensing technology.With analyses is of advantages and disadvantages of two systems,theoretical studyand experimental research has been conductedrespectively.First of all,based on the theory of gas absorption spectrum,e.g.Beer-Lambert principle and differential absorption method,the optical fiber methane gas detection system has been designed andexperimentally realized.The optical fiber structure including theoptical switch canrealize the real-time detection of 7 channel signals.The proof-of-principle production and performance test of the prototypeequipment is completed.The detection accuracy of the system is up to 271 ppm.Furthermore,in consideration of system stability,gasdiversity and entirecost,this paper also proposes another multiple gas detection system based on optical-electric modulation and optical fiber transmission.Itcombined the electro-optical modulation technology withtraditional gas sensors,realizing the optical fiber network for long distance transmission and multiplexing detection information processing.Throughthe feasibility analysis and preliminary study,the theoretical research and experimental testing of the system is presented,achieving the acquisition and transmission of sensing signal accurately.
Keywords/Search Tags:Optical fiber gas sensors, Spectrum absorption, Multi-point detection, Differential optical absorption spectroscopy, optical-electric modulation
PDF Full Text Request
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