Evaluating Low-Cost Commercially Available Sensors for Air Quality Monitoring and Application of Sensor Calibration Methods for Improving Accuracy

In this paper, we present the results of the evaluation of three low-cost laser sensors and comparison with the standard device Metone Aerocet 531s which is capable of counting dust particles as small as 0.3 μm. The sensors used in this study are PMS5003 (Plantower), SPS30 (Sesirion), SM-UART-04L (Amphenol). During the measurement, the overall trend of the outputs from the sensors was similar to that of the Aerocet 531s. The PMS5003 sensor has a relatively small standard error in the all particle measurement ranges (<15 μg/m3 in the low particle concentration range). All sensors have a high linearity compared to data from standard equipment, PMS5003: PM1.0 R2 = 0.89;PM2.5 R2 = 0.95;PM10 R2 = 0.87;SPS30 PM2.5 R2 = 0.95 and PM10 R2 = 0.99;SM-UART-04L PM1.0 R2 = 0.98. Three main sensor calibration methods (single-point calibration, two-point calibration and multi-point curve correction) with implementation steps for each method as well as their practical applications in calibrating low-cost air quality sensors according to standard measuring equipment are also detailed illustrated.

Low-Cost Sensors Calibration for Monitoring Air Quality in the Federal District—Brazil

Critical situations that cannot be solved by conventional approaches (traditional air quality monitoring networks), have the possibility of being managed quickly by a wide network of portable systems with sensors. The purpose of this research was to calibrate and validate low-cost sensors. Pilot indoor and outdoor areas, in the central area of Brasilia (Brazil’s capital city) were chosen for corporative performance evaluation of the sensors. The CO at 99.999% volumetric injection method has been used in a gas test box, among two MiCS-5521 (CO/VOC) sensors, one being new and the other one with a short useful life. The number of injections adopted to each volume (from 1 ml to 6 ml) was 10, rising each sensor’s confidence interval mean. A increase of the injected volume (ml) of CO resulted in significant decrease in a resistance (Ohms), as shown by a good inverse relationship on the interaction of these two variables (r = 0.88), with good measurement accuracy, when compared to the manufacturer’s reference datasheet. Finally, a geospatial management system was built for the pollution data measured by the low-cost sensors.

Homomorphic Hashing Verification for Wireless Sensor Networks Rateless Codes Over-the-Air Programming

The homomorphic hash algorithm(HHA)is introduced to help on-the-fly verify the vireless sensor network(WSN)over-the-air programming(OAP)data based on rateless codes.The receiver calculates the hash value of a group of data by homomorphic hash function,and then it compares the hash value with the receiving message digest.Because the feedback channel is deliberately removed during the distribution process,the rateless codes are often vulnerable when they face security issues such as packets contamination or attack.This method prevents contaminating or attack on rateless codes and reduces the potential risks of decoding failure.Compared with the SHA1 and MD5,HHA,which has a much shorter message digest,will deliver more data.The simulation results show that to transmit and verify the same amount of OAP data,HHA method sends 17.9% to 23.1%fewer packets than MD5 and SHA1 under different packet loss rates.

Enhancing Patients Outcomes and Infection Control through Smart Indoor Air Quality Monitoring Systems

Air pollution poses a critical threat to public health and environmental sustainability globally, and Nigeria is no exception. Despite significant economic growth and urban development, Nigeria faces substantial air quality challenges, particularly in urban centers. While outdoor air pollution has received considerable attention, the issue of indoor air quality remains underexplored yet equally critical. This study aims to develop a reliable, cost-effective, and user-friendly solution for continuous monitoring and reporting of indoor air quality, accessible from anywhere via a web interface. Addressing the urgent need for effective indoor air quality monitoring in urban hospitals, the research focuses on designing and implementing a smart indoor air quality monitoring system using Arduino technology. Employing an Arduino Uno, ESP8266 Wi-Fi module, and MQ135 gas sensor, the system collects real-time air quality data, transmits it to the ThingSpeak cloud platform, and visualizes it through a user-friendly web interface. This project offers a cost-effective, portable, and reliable solution for monitoring indoor air quality, aiming to mitigate health risks and promote a healthier living environment.

Design and Implementation of Batch Calibration System for Platinum Resistance Temperature Sensors

Developing a calibration and collection system of platinum resistance temperature sensor using Python language environment can read the information returned by the serial port and automatically generate an"Temperature Sensor Calibration Record Table"excel table with the current date as the file name.It can collect data from 10 platinum resistance temperature sensors at once,achieving automation and improving work efficiency.

An Optical Fiber Sensor Probe Using a PMMA/CPR Coated Bent Optical Fiber as a Transducer for Monitoring Trace Ammonia

Ammonia sensors have broad spectrum of applications for industrial process control as well as for environ-mental monitoring. An optical fiber ammonia sensor probe has been developed by using a bent optical fiber having dual poly(methyl methacrylate) (PMMA)/chlorophenol red (CPR) coatings as a transducer. This sen-sor probe was tested for monitoring trace ammonia in gas samples using air as sample matrix. The reaction of ammonia with CPR causes a color change of the reagent, which was detected by using fiber optic evanes-cent wave absorption spectrometry as a sensing signal. By adopting a dual layer coating structure, the sensor probe has faster response compared to a sensor using a broadly accepted sensing reagent-immobilized poly-mer coating structure. The sensor developed in this work is sensitive, has a detection limit of 2.7 ppb NH3 in air, which is the most sensitive among the reported optical fiber ammonia sensors to the best knowledge of the authors. The sensor is also reversible and has a response time of 25 minutes. The features of high sensi-tivity, reversibility and reasonable response time make this sensor technique very attractive for air quality monitoring.

Wireless Low Cost CO₂Monitoring System Design and Evaluation Using Non Dispersive Infrared Sensor

This paper presents a new wireless system for the measurement of CO2 gas concentration for indoor and outdoor purposes based on low cost Non Dispersive Infrared sensors. The system has been implemented on a printed circuit board in order to obtain different aspects of the air pollution. Some experiments were achieved to evaluate the total system combined with an android application on a smartphone. Different tests were realized in a closed room nearly filled with students and also directly while driving on the road. Good results were obtained allowing a future use for air pollution mapping using numerous amounts of sensors inside vehicles.

Real Time Dynamic Study of Amperometric Exhaust Oxygen Sensors

Previously,we had identified the various dynamic mechanisms of a wide range air to fuel ratio sensor operated in the engine exhaust by using the transfer function approach.In this study,we utilized these results to model the real time sensor response to an engine exhaust excursion.In the fitting,we identified a new dynamic mechanism,which was not detected in the previous transfer function study.This new dynamic occurred at the stoichiometric point when the engine changed from rich to lean.This new mechanism involved the depletion of the adsorbed fuel species on the electrode surface by an oxidation process. The dynamics of this effect depends on the ratio of the diffusion flux of the sensor-coating layer to the total adsorbed gas species on the electrode surface.The smaller the ratio is,the slower the dynamic mechanism will be.

智能化气垫带式输送机性能测试平台设计

该文设计了一种智能化气垫带式输送机性能测试平台,通过调节气室入口的风压、风速,气孔排布方式、孔径及孔间距,可探究气室气压、气膜边缘风速及气膜厚度的变化规律。平台基于可控文丘里装置的反馈系统控制气垫带式输送机的气流,实验平台可以反映输入气流参数与形成气膜参数之间的耦合关系,将抽象的相关知识具象化,加深学生对气垫式输送装备的理解。

MEMS Thermal Sensor在人感空调上的应用

介绍MEMS Thermal Sensor(微电子机械红外传感系统)的基本原理,基于Freescale单片机实现MEMS Thermal Sensor在人感空调上的应用以及具体实现方法。

提质培优背景下高职“课堂革命”的实践研究——以汽车专业空燃比传感器检修课程教学为例

在提质培优背景下,以抚顺职业技术学院汽车制造与试验技术专业(以下简称“汽车专业”)的核心课程汽车发动机电控系统检修为研究对象,针对该课程在传统教学中存在的实际问题,选取汽车空燃比传感器检修任务模块,深入开展课堂革命,分别从课程思政、教学设计、教学模式、教学环境和教学评价等方面进行创新研究,探索课堂教学改革新路径,构建“岗课赛证”融合育人模式,设计“三段十步”教学过程,打造有德、有用、有趣、有景、有效“五有”课堂,凸显职业教育教学特色,提高汽车专业人才培养质量和就业质量。

变频空调压缩机电机传感器振动噪声主动抑制方法研究

由于变频空调压缩机电机内部结构复杂性高,噪声源分布在不同的位置,使识别抑制范围受到限制,导致最终得出的信噪比较低。为此提出变频空调压缩机电机传感器振动噪声主动抑制方法,采用多点位的方式打破识别抑制范围受到的限制,进行噪声源多点位识别与噪声特征频率计算。基于此,构建传感器振动噪声主动抑制有限元仿真模型,采用定子模态解析对比的方式完成主动抑制处理。测试结果表明,所提方法计算得出的信噪比均可以达到60 dB以上,对于传感器产生的振动噪声进行捕捉,并主动抑制处理,噪声抑制效果得到进一步提升,具有实际的应用价值。

传感器位置对大型冷库库内温度及风机运行规律的影响

目前,冷库多通过库内布置传感器所采集的温度信号控制冷风机启停,进而维持适宜贮存温度。为探索不同位置传感器对大型冷库库内温度及风机运行时长的影响,本文以一实际使用的大型冷库为为原型构建计算模型,模拟研究了不同传感器位置导致风机运行规律变化,进而引起冷库温度波动情况。结果表明,“冷库升温”过程中,传感器布置在侧墙中部响应效果最佳;“关门降温”过程,传感器平行侧墙布置在冷库中部时,所导致的风机能耗最小;“开门降温”过程,传感器平行布置在冷库中间可以实现风机最佳的响应时间。

基于主元分析的温室物联网空气温湿度传感器故障诊断

针对温室物联网测控系统中空气温湿度传感器受恶劣环境影响易发生故障的问题,研究温室物联网测控系统中空气温湿度传感器的故障诊断,保障温室物联网测控系统整体工作的稳定可靠性,提出一种基于主元分析的空气温湿度传感器故障诊断方法。首先对空气温湿度传感器数据进行主元分析,通过监控平方预测误差统计量的变化实现传感器的故障检测;再针对检测出的空气温湿度传感器故障数据,利用加权后的平方预测误差统计量来计算传感器的累积贡献率,并将其作为传感器故障识别的指标,识别出现故障的空气温湿度传感器。利用空气温湿度传感器数据在不同故障条件下进行传感器故障诊断方法验证,验证结果表明:所提方法可用于温室物联网测控系统中空气温湿度传感器偏差故障和漂移故障的检测,偏差故障的检测效果要好于漂移故障,偏差故障综合检测率为100%,漂移故障综合检测率为51.25%;同时所提方法能够正确识别出故障传感器,有效提高温室物联网测控系统中空气温湿度传感器故障诊断结果的准确性。

基于线激光的压缩机曲轴圆度和平面度测量

目前人工使用千分表测量空调压缩机曲轴圆度和平面度时存在易伤工件表面、效率低和不能精确评定等问题。针对上述问题,设计了一套基于线激光位移传感器的空调压缩机曲轴圆度和平面度非接触式测量系统。首先,通过测量标准量棒,提出一种系统误差的标定方法;其次,基于线激光采样数据,开发了一种曲轴横截面圆度测点的提取算法,并将系统误差用于测点补偿,实现曲轴圆度测量;接着根据曲轴平面测点间的斜率分离出轮廓线,通过均匀下采样方法获取精简点云数据并采用最小二乘法实现曲轴平面度测量;最后,基于上述方法开展了曲轴圆度和平面度的测量实验。实验结果表明:该测量系统的圆度测量精度<4μm,平面度测量精度<2μm,圆度重复度测量误差<0.8μm,平面度重复度测量误差<0.3μm,满足曲轴圆度和平面度快速准确的测量需求。

基于双模型自适应估计的大气数据传感器故障诊断方法

大气湍流是大气中一种不规则的随机运动,在机载大气数据传感器的测量过程中,大气湍流影响与传感器故障相互耦合,导致大气数据传感器故障诊断算法无法将故障与湍流影响解耦。针对大气湍流影响下的大气数据传感器故障诊断问题,基于惯性测量单元和导航姿态解算,考虑湍流对大气系统的影响,建立新型大气系统模型及量测模型。在对双模型自适应估计算法进行扩展后,引入湍流对系统影响的协方差自适应更新方法,实现存在未知扰动情况下故障状态的无偏估计。仿真结果表明,该算法可以有效实现对固定偏差故障、漂移偏差故障和振荡故障的诊断。

移动监测技术在大气环境研究中的应用

移动监测是把用于环境监测的设备安装在移动载体(汽车、自行车、无人机和船等)上,开展环境质量监测的技术。移动监测技术以其灵活、机动、及时等优势,近年来被广泛应用于大气环境监测中,但针对移动监测技术在大气环境研究中的应用场景及其存在的优缺点等缺少系统性研究。通过文献调研的方式对国内外移动监测技术在大气环境研究中的应用进行综述,重点讨论了监测设备及其搭载平台。将移动监测设备划分为传感器和大型设备2类,其中传感器以体积小、成本低等优势被大量应用在无人机、汽车等平台中。大型设备则包括监测仪和分析仪,但由于受到体积和成本的限制多被应用在飞机和船等面积较大的平台中。根据大气环境移动监测设备搭载的平台将其划分为车载移动监测、机载移动监测和船载移动监测三大类,其中车载移动监测主要用于环境质量监测、溯源分析和热点监测、汽车尾气排放监测及空气污染暴露监测等,机载移动监测主要用于环境空气质量监测、溯源分析和热点监测及大气污染物传输监测,船载移动监测主要用于海表大气组分、溯源分析和船舶尾气排放等研究。最后讨论了移动监测平台现有应用中存在的问题(例如覆盖率、续航、数据质量等),并对未来研究进行了展望。

智能雨水晾衣监测装置研究

智能雨水晾衣监测装置采用单片机作为主要控制芯片,由温湿度传感器、风速传感器、雨滴传感器、光敏传感器获取外界的信息。传感器所采集到空气温湿度、风力大小、光照强度以及是否正在下雨等信息,由单片机处理后对步进电机进行控制,实现防水布的伸出与收缩。装置可以选择自动避雨和手动避雨两种模式。设计电路采用仿真软件在电脑上进行仿真,极大地减少设计成本,直观地发现装置设计的缺点,也能更好地验证该装置的正确性。

基于电容传感器的液体管内含气率测量系统的研究

电容传感器具有非侵入式、低成本、结构简单等特点,被广泛应用于液体管内含气率的测量。基于电容传感器,设计了含气率测量系统,对外径25mm、内径21mm液体管内含气率进行测量。为了验证含气率测量系统的准确性,搭建了可视化验证平台。对管内气液两相进行图像采集,对管道截面处的含气率进行计算;分析了视窗左右截面的含气率偏差,研究了采集位置偏差对验证方法有效性的影响。研究表明:通过传感器系统测量的含气率与图像处理得到的含气率吻合;视窗左右截面的平均含气率的偏差不超过3.097%。本研究设计的含气率测量系统的准确性较好,所提出的可视化验证方法能够有效地对含气率测量系统的准确性进行验证。

基于某款轿车的空气流量计故障检测与分析研究

燃油汽车发动机空气流量传感器作为精确控制空燃比的重要元件,其性能直接影响到了发动机的正常运转。空气流量传感器异常会使得发动机出现怠速不稳或者动力下降等问题,但在实际检修过程中仅用一种方法无法确定故障原因。本文以某款轿车为例,详细阐述了空气流量计的作用、分类及工作原理,并详细介绍了空气流量传感器的实际检测方法;以发动机怠速不稳的故障现象为例,提供了空气流量传感器的多种故障诊断和排除思路,为之后的汽车维修研究提供借鉴。