【作者】 华莹；

【导师】 郑传涛；

【作者基本信息】 吉林大学 ， 电路与系统， 2024， 硕士

【摘要】 二氧化碳（CO₂）是全球排放占比最大的温室气体。城市人口聚集性高,经济活动集中,生活和工业碳排放强度大,监测城市碳排放情况能为制定节能减排政策提供依据。衡量城市碳排放水平的重要手段是监测大气CO₂浓度,这一过程需要高精度CO₂传感器。城市面积辽阔,测量范围广,组建多节点传感器网络成本高,因此,需要通过车载传感器的方式来实现城市二氧化碳排放移动监测。在气体检测技术中,红外气体检测技术具有选择性好、检测精度高、响应速度快等优点。离轴积分腔输出光谱（Off-axis Integrated Cavity Output Spectroscopy,OA-ICOS）技术在近红外波段可以实现ppb（parts per billion,十亿分之一）量级检测。为了评估城市CO₂排放情况,研制了一套基于OA-ICOS的城市二氧化碳排放移动监测系统。具体内容如下:设计了城市二氧化碳排放移动监测系统的结构。仿真了CO₂在1.572μm和2.004μm波段的吸收光谱,选择1.572μm作为目标吸收谱线。设计了传感器系统的整体结构,由光学子系统、气体预处理子系统、电学子系统和远程监测与控制系统组成。光学子系统集成了分布反馈激光器、探测器和谐振腔,腔长为30 cm,高反镜反射率大于99.97%（1640～1700 nm）。气体预处理子系统抽取气体并对其除尘和除湿。研制了城市二氧化碳排放移动监测系统的硬件电路。设计了电源电路、激光器外部控温模块与主控电路。电源电路为其他电学模块提供电源。激光器外部控温模块采用大功率半导体制冷器（Thermo Electric Cooler,TEC）,用于解决在低温环境下激光器无法自主控温的问题,拓宽了仪器的工作温度范围。主控电路以DSP和多核ARM处理器为主芯片,包括电源电路、激光器驱动信号产生电路、探测器输出信号采样电路、激光器驱动电流与温度采集电路、外设接口电路等。主控电路实现了全部核心功能,提高了电学子系统的集成度。开发了城市二氧化碳排放移动监测系统的软件程序。基于消息队列遥测传输（Message Queuing Telemetry Transport,MQTT）协议,设计了由主控电路（本地端）、云端服务器和安卓应用程序（远程端）构成的远程监测与控制系统,实现了传感器系统的网络化。开发了本地端软件:在DSP部分,编写了直接数字式频率合成器（Direct Digital Synthesizer,DDS）配置程序、数据采集程序等;在ARM部分,移植了Linux操作系统,编写了Linux底层驱动程序和上层Qt程序。基于多线程编程技术,实现了用户登录、数据监测、激光器控制、数据存储、网络发布、人机交互等功能。配置了云端服务器,基于My SQL数据库设计了用于云端数据存储的后台程序。开发了安卓应用程序（Application,APP）,用于远程数据监测及设备控制,实现了用户登录、绘制实时与历史浓度曲线、显示实时与历史测量轨迹、下载数据、远程监测仪器状态与控制激光器功能。完成了系统的集成与应用实验。考虑车载移动探测需求,对传感器进行了集成和减振处理。为了测试仪器的性能指标,采用直接吸收光谱（Direct Absorption Spectroscopy,DAS）技术,开展了系统标定、光程标定、响应时间与稳定性测试实验。测试结果显示,系统的有效光程约为428 m;当积分时间为0.5 s时,检测下限（1σ）为62.8 ppb;上升时间约为9 s,下降时间约为25 s。开展了室内CO₂浓度监测实验,浓度整体平稳,传感器响应浓度变化的速度快。通过车载方式,开展了长春市CO₂浓度测量实验,结果表明冬季CO₂浓度偏高,且市区浓度高于郊区。本论文的创新点如下:（1）在激光器内部控温的基础上,设计了激光器外部控温模块,形成两级控温方式,扩大了激光器的工作温度范围,在低温环境下实现了传感器系统的正常工作。（2）针对移动探测应用需求,设计了集成全部核心功能的主控电路板,提高了电学子系统的集成度,降低了功耗,方便了系统管理。（3）研制了由主控电路、云端服务器和安卓APP构成的远程监测与控制系统,实现了远程数据监测、激光器控制、轨迹显示等功能,提高了系统的网络化水平。更多还原

【Abstract】 Carbon dioxide（CO₂）is the greenhouse gas with the largest share of global emissions.Urban population is highly clustered,economic activities are concentrated,and the domestic and industrial carbon emission intensity is high.Monitoring urban carbon emissions can provide a basis for formulating energy conservation and emission reduction policies.An important means to measure the level of urban carbon emissions is to monitor the atmospheric CO₂ concentration,which requires a high-precision CO₂ sensor.The urban area is vast,the measurement range is wide,and the cost of building a multi-node sensor network is high.Therefore,it is necessary to realize mobile monitoring of urban carbon dioxide emissions through a vehicle mounted sensor.In gas detection technology,infrared gas detection technology has the advantages of good selectivity,high detection precision,fast response speed and so on.Off-axis Integrated Cavity Output Spectroscopy（OA-ICOS）can detect parts per billion（ppb）in the near infrared band.In order to evaluate urban CO₂ emission,a mobile monitoring system for urban CO₂ emission based on OA-ICOS technology was developed.The details are as follows:The structure of the urban CO₂ emissions mobile monitoring system was designed.The absorption spectra of CO₂ in 1.572μm and 2.004μm bands were simulated,and 1.572μm was selected as the target absorption spectrum line.The overall structure of the sensor system was designed,which consists of optical subsystem,gas pretreatment subsystem,electrical subsystem,remote monitoring and control system.The optical subsystem integrates a distributed feedback laser,a detector and a cavity.The length of the cavity is30 cm and the reflectivity of the highly reflective mirrors is more than 99.97%（1640～1700 nm）.The gas pretreatment subsystem extracts the gas and dedusts and dehumidifies it.The hardware circuit of urban carbon dioxide emissions mobile monitoring system was developed.The power supply circuit,laser external temperature control module and main control circuit were designed.The power circuit provides power to other electrical modules.The laser external temperature control module was designed with high-power Thermo Electric Cooler（TEC）to solve the problem that the laser cannot control the temperature by itself in low temperature environment,and broadened the operating temperature range of the instrument.The main control circuit is based on DSP and multi-core ARM processor,including power supply circuit,laser drive signal generation circuit,detector output signal sampling circuit,laser drive current and temperature acquisition circuit,peripheral interface circuit,etc.The main control circuit realized all the core functions and improved the integration of the electrical subsystem.The software program of urban CO₂ emissions mobile monitoring system was developed.Based on Message Queuing Telemetry Transport（MQTT）protocol,a remote monitoring and control system was designed,which consists of the main control circuit（local end）,cloud server and Android application（remote end）,and the network of sensor system is realized.The local software is developed:in the DSP part,the Direct Digital Synthesizer（DDS）configuration program,data acquisition program and other programs were written.In the ARM part,the Linux operating system was transplanted,and the Linux bottom driver and the upper Qt program were written.Based on multi-thread programming technology,user login,data monitoring,laser control,data storage,network publishing,human-computer interaction and other functions were realized.The cloud server was configured,and the background program for cloud data storage was designed based on My SQL database.An Android Application（APP）was developed for remote data monitoring and device control,which realized the functions of user login,drawing real-time and historical concentration curves,displaying real-time and historical measurement trajectories,downloading data,remote monitoring of instrument status and laser control.The integration and application of the system were completed.Considering the demand of vehicle-mounted mobile detection,the sensor was integrated and vibration reduction processing was carried out.In order to test performance indexes of the instrument,Direct Absorption Spectroscopy（DAS）technology was used to carry out system calibration,optical path calibration,response time and stability testing experiments.The test results show that the effective optical path of the system is about 428 m.When the integration time is 0.5 s,the lower detection limit（1σ）is 62.8 ppb.The rise time is about 9 s and the fall time is about 25 s.The indoor CO₂ concentration monitoring experiment was carried out,the overall concentration was stable,and the sensor could respond to the concentration change quickly.The measurement experiment of CO₂concentration in Changchun city was carried out by vehicle.The results showed that the CO₂ concentration was higher in winter,and the concentration in urban area was higher than that in suburban area.The innovations of this paper are as follows:（1）On the basis of the internal temperature control of the laser,the external temperature control module was designed to form a two-stage temperature control mode,which expanded the operating temperature range of the laser and realized the normal operation of the sensor system under low temperature environment.（2）According to the application requirements of mobile detection,a main control circuit board integrating all core functions was designed to improve the integration of electrical subsystems,reduce power consumption and facilitate system management.（3）A remote monitoring and control system composed of main control circuit,cloud server and Android APP was developed,which realized remote data monitoring,laser control,trajectory display and other functions,and improved the network level of the system.更多还原