scholarly journals Seasonal Influence on the Performance of Low-Cost NO2 Sensor Calibrations

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7919
Author(s):  
Sjoerd van Ratingen ◽  
Jan Vonk ◽  
Christa Blokhuis ◽  
Joost Wesseling ◽  
Erik Tielemans ◽  
...  
Keyword(s):  
Low Cost ◽  
Added Value ◽  
Sensor Data ◽  
Sensor Technology ◽  
Monitoring Networks ◽  
Technical Problems ◽  
Eu Directive ◽  
Short Period ◽  
No2 Sensor ◽  
One Year

Low-cost sensor technology has been available for several years and has the potential to complement official monitoring networks. The current generation of nitrogen dioxide (NO2) sensors suffers from various technical problems. This study explores the added value of calibration models based on (multiple) linear regression including cross terms on the performance of an electrochemical NO2 sensor, the B43F manufactured by Alphasense. Sensor data were collected in duplicate at four reference sites in the Netherlands over a period of one year. It is shown that a calibration, using O3 and temperature in addition to a reference NO2 measurement, improves the prediction in terms of R2 from less than 0.5 to 0.69–0.84. The uncertainty of the calibrated sensors meets the Data Quality Objective for indicative methods specified by the EU directive in some cases and it was verified that the sensor signal itself remains an important predictor in the multilinear regressions. In practice, these sensors are likely to be calibrated over a period (much) shorter than one year. This study shows the dependence of the quality of the calibrated signal on the choice of these short (monthly) calibration and validation periods. This information will be valuable for determining short-period calibration strategies.

scholarly journals Low-Cost Air Quality Sensors: One-Year Field Comparative Measurement of Different Gas Sensors and Particle Counters with Reference Monitors at Tušimice Observatory

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 492 ◽  
Author(s):  
Petra Bauerová ◽  
Adriana Šindelářová ◽  
Štěpán Rychlík ◽  
Zbyněk Novák ◽  
Josef Keder
Keyword(s):  
Air Quality ◽  
Gas Sensors ◽  
Low Cost ◽  
Monitoring Network ◽  
Field Testing ◽  
Ambient Air ◽  
Monitoring Networks ◽  
Comparative Measurement ◽  
One Year ◽  
Pm2.5 And Pm10

With attention increasing regarding the level of air pollution in different metropolitan and industrial areas worldwide, interest in expanding the monitoring networks by low-cost air quality sensors is also increasing. Although the role of these small and affordable sensors is rather supplementary, determination of the measurement uncertainty is one of the main questions of their applicability because there is no certificate for quality assurance of these non-reference technologies. This paper presents the results of almost one-year field testing measurements, when the data from different low-cost sensors (for SO2, NO2, O3, and CO: Cairclip, Envea, FR; for PM1, PM2.5, and PM10: PMS7003, Plantower, CHN, and OPC-N2, Alphasense, UK) were compared with co-located reference monitors used within the Czech national ambient air quality monitoring network. The results showed that in addition to the given reduced measurement accuracy of the sensors, the data quality depends on the early detection of defective units and changes caused by the effect of meteorological conditions (effect of air temperature and humidity on gas sensors and effect of air humidity with condensation conditions on particle counters), or by the interference of different pollutants (especially in gas sensors). Comparative measurement is necessary prior to each sensor’s field applications.

scholarly journals Long-term behavior and stability of calibration models for NO and NO<sub>2</sub> low cost sensors

2022 ◽  
Author(s):  
Horim Kim ◽  
Michael Müller ◽  
Stephan Henne ◽  
Christoph Hüglin
Keyword(s):  
Electrochemical Sensors ◽  
Low Cost ◽  
Air Pollutant ◽  
Coefficient Of Determination ◽  
Monitoring Networks ◽  
Pollution Levels ◽  
Pollutant Concentrations ◽  
Air Quality Measurements ◽  
One Year

Abstract. Low-cost sensors are considered as exhibiting great potential to complement classical air quality measurements in existing monitoring networks. However, the use of low-cost sensors poses some challenges. In this study, the behavior and performance of electrochemical sensors for NO and NO2 were determined over a longer operating period in a real-world deployment. After careful calibration of the sensors, based on co-location with reference instruments at a rural traffic site during six months and by using robust linear regression and random forest regression, the coefficient of determination of both types of sensors were high (R2 > 0.9) and the root mean square error (RMSE) of NO and NO2 sensors were about 6.8 ppb and 3.5 ppb, respectively, for 10-minute mean concentrations. The RMSE of the NO2 sensors, however, more than doubled, when the sensors were deployed without re-calibration for a one-year period at other site types (including urban background locations), where the range and the variability of air pollutant concentrations differed from the calibration site. This indicates a significant effect of the re-location of the sensors on the quality of their data. During deployment, we found that the NO2 sensors are capable of distinguishing general pollution levels, but they proved unsuitable for accurate measurements, mainly due to significant biases. In order to investigate the long-term stability of the original calibration, the sensors were re-installed at the calibration site after deployment. Surprisingly, the coefficient of determination and the RMSE of the NO sensor remained almost unchanged after more than one year of operation. In contrast, the performance of the NO2 sensors clearly deteriorated as indicated by a higher RMSE (about 7.5 ppb, 10-minute mean concentrations) and a lower coefficient of determination (R2 = 0.59).

scholarly journals Vayu: An Open-Source Toolbox for Visualization and Analysis of Crowd-Sourced Sensor Data

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7726
Author(s):  
Sachit Mahajan
Keyword(s):  
Air Quality ◽  
Open Source ◽  
Time Series Data ◽  
Sensor Data ◽  
Quality Data ◽  
Sensor Technology ◽  
Data Conversion ◽  
Series Data ◽  
Monitoring Networks ◽  
Systematic Analysis

Recent advances in sensor technology and the availability of low-cost and low-power sensors have changed the air quality monitoring paradigm. These sensors are being widely used by scientists and citizens for monitoring air quality at finer spatial-temporal resolution. Such practices are opening up opportunities to enhance the traditional monitoring networks, but at the same time, these sensors are producing large data sets that can become overwhelming and challenging when it comes to the scientific tools and skills required to analyze the data. To address this challenge, an open-source, robust, and cross-platform sensor data analysis toolbox called Vayu is developed that allows researchers and citizens to do detailed and reproducible analyses of air quality data. Vayu combines the power of visualization and statistical analysis using a simple and intuitive graphical user interface. Additionally, it offers a comprehensive set of tools for systematic analysis such as data conversion, interpolation, aggregation, and prediction. Even though Vayu was developed with air quality research in mind, it can be used to analyze different kinds of time-series data.

scholarly journals Static, Portable and Smart Detection of Water Quality in Panchayath Distribution Tank

2019 ◽  
Vol 8 (2S5) ◽  
pp. 103-108
Keyword(s):  
Real Time ◽  
Low Cost ◽  
Cost Effective ◽  
Daily Basis ◽  
Quality Parameters ◽  
Sensor Data ◽  
Sensor Technology ◽  
Real Time System ◽  
Quality Of Water ◽  
Physical And Chemical

The significant crunch in the Current world is Water pollution. It has created an abundant influence on the Environment. With the intention of the non-toxic distribution of the water and its eminence should be monitored at real time. This paper suggested the smart detection with low cost real time system which is used to monitor the quality of water through IOT(internet of things). The system entail of different sensors which are used to measure the physical and chemical parameters of the water. The quality parameters are temperature, pH, turbidity, conductivity and Total dissolved solids of the water are measured. Commercially available products capable of monitoring such parameters are usually somewhat expensive and the data’s are collected by mobile van. Using Sensor technology provides a cost-effective and pre-eminent reliable as they can provide real time output. The measured values from the sensors can be observed by the core controller. The controller was programmed to monitor the distribution tank on a daily basis to hour basis monitoring. The TIVA C series is used as a core controller. The Controller is mounted on the side of the distribution tank. Finally, the sensor data from the controller is sent to Wi-Fi module through UART protocol. Wi-fi Module is connected to a public Wi-Fi system through which data is seen by the locals who are all connected to that Wi-Fi network.

scholarly journals Ponseti technique: efficacy in idiopathic clubfoot in Indian population

2018 ◽  
Vol 4 (4) ◽  
pp. 614
Author(s):  
Neetin Mahajan ◽  
Ujwal Ramteke ◽  
Sandeep Gavhale ◽  
Nikhil Palange ◽  
Akash Mane ◽  
...  
Keyword(s):  
Low Cost ◽  
Ponseti Method ◽  
Idiopathic Clubfoot ◽  
Acceptable Result ◽  
Short Period ◽  
Strict Compliance ◽  
Analysis Of Results ◽  
One Year ◽  
Non Surgical Treatment

<p class="abstract"><strong>Background:</strong> The number of operations for clubfoot is many, but the results are not encouraging and more complications are encountered after operative treatment. Most surgeons believe manipulation to be easy; however they rarely complete the treatment and abandon it and go on to surgery. In the confusing scenario Ponseti Method evolved and proved across the world to be one of the most promising ways to correct club foot with low cost minimum surgery and good result in short period of time.</p><p class="abstract"><strong>Methods:</strong> 50 cases of idiopathic clubfeet (76 feet) were enrolled from a period of May 2006 to May 2008 in the department of Orthopaedic. Out of 50, 42 patients were followed-up for two years. Post tenotomy follow-up done every monthly for 3 months. At every visit babies were checked for any relapse and parents were counselled for the strict compliance with Foot Abduction Brace. The results of correction in 42 patients (64 feets) evaluated and compared with Ponseti's observation and other form of conservative management.<strong></strong></p><p class="abstract"><strong>Results:</strong> The analysis of results of correction of clubfeet deformity by Ponseti's method reveals around 95.30% of good to acceptable result as compared with Ponseti’s observation of around 99% which is comparable. We have observed 4.69% of poor result as compared with 1% observed by Ponseti.</p><p class="abstract"><strong>Conclusions:</strong> It is safe, efficient, Economical and most effective treatment for clubfoot which decreases the need for extensive corrective surgery. This technique can be used in children up to one year of age even after previous unsuccessful non-surgical treatment.</p>

scholarly journals Long-term field comparison of multiple low-cost particulate matter sensors in an outdoor urban environment

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Florentin M. J. Bulot ◽  
Steven J. Johnston ◽  
Philip J. Basford ◽  
Natasha H. C. Easton ◽  
Mihaela Apetroaie-Cristea ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Low Cost ◽  
Cost Effective ◽  
Personal Exposure ◽  
Monitoring Networks ◽  
Standard Equipment ◽  
Sensor Performance ◽  
Effective Manner ◽  
Micro Sensor ◽  
One Year

Abstract Exposure to ambient particulate matter (PM) air pollution is a leading risk factor for morbidity and mortality, associated with up to 8.9 million deaths/year worldwide. Measurement of personal exposure to PM is hindered by poor spatial resolution of monitoring networks. Low-cost PM sensors may improve monitoring resolution in a cost-effective manner but there are doubts regarding data reliability. PM sensor boxes were constructed using four low-cost PM micro-sensor models. Three boxes were deployed at each of two schools in Southampton, UK, for around one year and sensor performance was analysed. Comparison of sensor readings with a nearby background station showed moderate to good correlation (0.61 < r < 0.88, p < 0.0001), but indicated that low-cost sensor performance varies with different PM sources and background concentrations, and to a lesser extent relative humidity and temperature. This may have implications for their potential use in different locations. Data also indicates that these sensors can track short-lived events of pollution, especially in conjunction with wind data. We conclude that, with appropriate consideration of potential confounding factors, low-cost PM sensors may be suitable for PM monitoring where reference-standard equipment is not available or feasible, and that they may be useful in studying spatially localised airborne PM concentrations.

scholarly journals Toward Near Real-Time Kinematics Differential Correction: In View of Geometrically Augmented Sensor Data for Mobile Microclimate Monitoring

2020 ◽  
Vol 2 (1) ◽  
pp. 61
Author(s):  
Stefano Tondini ◽  
Farshad Hasanabadi ◽  
Roberto Monsorno ◽  
Antonio Novelli
Keyword(s):  
Urban Communities ◽  
Urban Areas ◽  
Global Climate ◽  
Low Cost ◽  
Life Quality ◽  
Environmental Parameters ◽  
Mitigation Strategies ◽  
Added Value ◽  
Sensor Data ◽  
Urban Context

In the scenario of massive urbanization and global climate change, the acquisition of microclimatic data in urban areas plays a key role in responsive adaptation and mitigation strategies. The enrichment of kinematic sensor data with precise, high-frequency and robust positioning directly relates to the possibility of creating added-value services devoted to improving the life-quality of urban communities. This work presents a low-cost cloud-connected mobile monitoring platform for multiple environmental parameters and their spatial variation in the urban context.

scholarly journals Autonomous Detection System for Non-Hard-Hat Use at Construction Sites Using Sensor Technology

2021 ◽  
Vol 13 (3) ◽  
pp. 1102
Author(s):  
Jung Hoon Kim ◽  
Byung Wan Jo ◽  
Jun Ho Jo ◽  
Yun Sung Lee ◽  
Do Keun Kim
Keyword(s):  
Heart Rate ◽  
Detection System ◽  
Low Cost ◽  
Sensor Data ◽  
Sensor Technology ◽  
Construction Sites ◽  
Novel Method ◽  
Validation Tests ◽  
Microcontroller Unit ◽  
Hard Hat

In this study, we present a novel method of detecting hard hat use on construction sites using a modified version of an off-the-shelf wearable device. The data-transmitting node of the device contained two sensors, a photoplethysmogram (PPG) and accelerometers (Acc), along with two modules, a global positioning system (GPS) and a low-power wide-area (LoRa) network module. All the components were embedded into a microcontroller unit (MCU) in addition to the power supply. The receiving node included a server that displayed the results via both the Internet of Things (IoT) and smartphones. The LoRa network connected two nodes so that it could function in larger areas such as construction sites at a relatively low cost. The proposed method analyzes the data from a PPG sensor located on the hard hat chin strap and automatically notifies a manager when a worker is not wearing the required hard hat at the site. In addition, by utilizing the PPG sensor data, a heart rate abnormality-detecting feature was added based on an age-adjusted maximum heart rate formula. In validation tests, various PPG sensor locations and shapes were studied, and the results demonstrated the smallest error in the circular shaped sensor located at the upper neck (0.56%). Finally, an IoT monitoring page was created to monitor heart rate abnormalities while identifying hard hat use violations via both PCs and smart phones.

scholarly journals Field calibration of electrochemical NO<sub>2</sub> sensors in a citizen science context

2018 ◽  
Vol 11 (3) ◽  
pp. 1297-1312 ◽  
Author(s):  
Bas Mijling ◽  
Qijun Jiang ◽  
Dave de Jonge ◽  
Stefano Bocconi
Keyword(s):  
Air Quality ◽  
Citizen Science ◽  
Low Cost ◽  
Weighted Average ◽  
Air Monitoring ◽  
Urban Setting ◽  
Added Value ◽  
Monitoring Station ◽  
Sensor Technology ◽  
Measurement Period

Abstract. In many urban areas the population is exposed to elevated levels of air pollution. However, real-time air quality is usually only measured at few locations. These measurements provide a general picture of the state of the air, but they are unable to monitor local differences. New low-cost sensor technology is available for several years now, and has the potential to extend official monitoring networks significantly even though the current generation of sensors suffer from various technical issues. Citizen science experiments based on these sensors must be designed carefully to avoid generation of data which is of poor or even useless quality. This study explores the added value of the 2016 Urban AirQ campaign, which focused on measuring nitrogen dioxide (NO2) in Amsterdam, the Netherlands. Sixteen low-cost air quality sensor devices were built and distributed among volunteers living close to roads with high traffic volume for a 2-month measurement period. Each electrochemical sensor was calibrated in-field next to an air monitoring station during an 8-day period, resulting in R2 ranging from 0.3 to 0.7. When temperature and relative humidity are included in a multilinear regression approach, the NO2 accuracy is improved significantly, with R2 ranging from 0.6 to 0.9. Recalibration after the campaign is crucial, as all sensors show a significant signal drift in the 2-month measurement period. The measurement series between the calibration periods can be corrected for after the measurement period by taking a weighted average of the calibration coefficients. Validation against an independent air monitoring station shows good agreement. Using our approach, the standard deviation of a typical sensor device for NO2 measurements was found to be 7 µg m−3, provided that temperatures are below 30 ∘C. Stronger ozone titration on street sides causes an underestimation of NO2 concentrations, which 75 % of the time is less than 2.3 µg m−3. Our findings show that citizen science campaigns using low-cost sensors based on the current generations of electrochemical NO2 sensors may provide useful complementary data on local air quality in an urban setting, provided that experiments are properly set up and the data are carefully analysed.

scholarly journals Practical field calibration of electrochemical NO<sub>2</sub> sensors for urban air quality applications

2017 ◽  
Author(s):  
Bas Mijling ◽  
Qijun Jiang ◽  
Dave de Jonge ◽  
Stefano Bocconi
Keyword(s):  
Air Quality ◽  
Low Cost ◽  
Weighted Average ◽  
Air Monitoring ◽  
Urban Setting ◽  
Added Value ◽  
Monitoring Station ◽  
Sensor Technology ◽  
Measurement Campaign ◽  
Field Calibration

Abstract. In many urban areas the population is exposed to elevated levels of air pollution. However, air quality is usually only measured at a few locations. These measurements provide a general picture of the state of the air, but they are unable to monitor local differences. Since a few years new low-cost sensor technology is available, which has the potential to extend the official monitoring network significantly. These sensors, however, are still in an experimental stage and suffer from various technical issues which limit their applicability. This study explores the added value of alternative air quality measurements, focusing on nitrogen dioxide (NO2) in Amsterdam, the Netherlands. 16 low-cost air quality sensor devices were built and distributed among volunteers living close to roads with high traffic volume for a two-month measurement campaign. Careful calibration of individual sensors is essential to measure ambient concentrations of NO2 significantly. Field calibration was done next to an air monitoring station during an 8-day period, resulting in R2 ranging from 0.3 to 0.7. The NO2 accuracy can be improved by including temperature and humidity measurements from an additional low-cost sensor, R2 ranging from 0.6 to 0.9. Recalibration is crucial, as all sensors show significant signal drift after the two-month measurement campaign. The measurement series between the calibration periods can be corrected in hindsight by taking a weighted average of the calibration coefficients. Validation against an independent air monitoring station shows good agreement. Using our approach, the standard deviation of a typical sensor device for NO2 measurements was found to be 7 μg m−3. This shows that, if properly treated, low-cost sensors based on the current generations of electrochemical NO2 sensors may provide useful complementary data on local air quality in an urban setting.

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