Reference Instrument Research Articles

Evaluation of Aircraft Emissions at Bucharest Henri Coanda Airport

This study presents the influence of aircraft movements on air quality by highlighting the contribution of landings and/or takeoffs at Henri Coanda Airport, Bucharest. An experimental campaign was carried out using a mobile laboratory equipped with reference instruments for the main air pollutants (NO-, NO2, NOx, SO2, CO, and O3) and a meteorological station to measure wind speed and direction, air temperature, pressure, and relative humidity at a height of 10 m above the ground. The mobile testing laboratory was located inside the airport near the passenger embarking area, and measurements were carried out for 7 days. Air sampling was carried out at a height of 3.5 m above the ground. Pollutant levels were continuously measured throughout the measurement period, with high-precision equipment and a 10-second interval. The results obtained showed an increase in pollutant concentrations during takeoffs and/or landings, providing an initial assessment of gaseous pollutant levels and hourly distribution. Airport authorities can use this assessment to balance aircraft and passenger movements to minimize human exposure to gaseous pollutants. Furthermore, this study used the Pearson correlation between each pollutant and meteorological parameters to establish the best conditions for passengers to be present on the airport premises. The results showed that wind speed and direction directly influence the distribution of gaseous pollutants, especially during landings and takeoffs.

Seasonally optimized calibrations improve low-cost sensor performance: long-term field evaluation of PurpleAir sensors in urban and rural India

Abstract. Lower-cost air pollution sensors can fill critical air quality data gaps in India, which experiences very high fine particulate matter (PM2.5) air pollution but has sparse regulatory air monitoring. Challenges for low-cost PM2.5 sensors in India include high-aerosol mass concentrations and pronounced regional and seasonal gradients in aerosol composition. Here, we report on a detailed long-time performance evaluation of a popular sensor, the Purple Air PA-II, at multiple sites in India. We established three distinct sites in India across land use categories and population density extremes (in urban Delhi and rural Hamirpur in north India and urban Bengaluru in south India), where we collocated the PA-II model with reference beta attenuation monitors. We evaluated the performance of uncalibrated sensor data, and then developed, optimized, and evaluated calibration models using a comprehensive feature selection process with a view to reproducibility in the Indian context. We assessed the seasonal and spatial transferability of sensor calibration schemes, which is especially important in India because of the paucity of reference instrumentation. Without calibration, the PA-II was moderately correlated with the reference signal (R2 = 0.55–0.74) but was inaccurate (NRMSE ≥ 40 %). Relative to uncalibrated data, parsimonious annual calibration models improved the PurpleAir (PA) model performance at all sites (cross-validated NRMSE 20 %–30 %; R2 = 0.82–0.95), and greatly reduced seasonal and diurnal biases. Because aerosol properties and meteorology vary regionally, the form of these long-term models differed among our sites, suggesting that local calibrations are desirable when possible. Using a moving-window calibration, we found that using seasonally specific information improves performance relative to a static annual calibration model, while a short-term calibration model generally does not transfer reliably to other seasons. Overall, we find that the PA-II model can provide reliable PM2.5 data with better than ±25 % precision and accuracy when paired with a rigorous calibration scheme that accounts for seasonality and local aerosol composition.

Comparison of photoacoustic spectroscopy and cavity ring-down spectroscopy for ambient methane monitoring at Hohenpeißenberg

Abstract. With an atmospheric concentration of approximately 2000 parts per billion (ppbV, 10−9), methane (CH4) is the second most abundant greenhouse gas (GHG) in the atmosphere after carbon dioxide (CO2). The task of long-term and spatially resolved GHG monitoring to verify whether climate policy actions are effective is becoming more crucial as climate change progresses. In this paper we report the CH4 concentration readings of our photoacoustic (PA) sensor over a 5 d period at Hohenpeißenberg, Germany. As a reference device, a calibrated cavity ring-down spectrometer, Picarro G2301, from the meteorological observatory of the German Weather Service (DWD) was employed. Trace gas measurements with photoacoustic instruments promise to provide low detection limits at comparably low costs. However, PA devices are often susceptible to cross-sensitivities related to fluctuating environmental conditions, e.g. ambient humidity. The obtained results show that for PA sensor systems non-radiative relaxation effects induced by varying humidity are a non-negligible factor. Applying algorithm compensation techniques, which are capable of calculating the influence of non-radiative relaxation effects on the photoacoustic signal, increase the accuracy of the photoacoustic sensor significantly. With an average relative deviation of 1.11 % from the G2301, the photoacoustic sensor shows good agreement with the reference instrument.

Low-cost sensors and Machine Learning aid in identifying environmental factors affecting particulate matter emitted by household heating

Poland continues to rely heavily on coal and fossil fuels for household heating, despite efforts to reduce Particulate Matter (PM) levels. The availability of reliable air quality data is essential for policymakers, environmentalists, and citizens to advocate for cleaner energy sources. However, Polish air quality monitoring is challenging due to the limited coverage of reference stations and outdated equipment. Here, we report the results of a study on the spatio-temporal variability of Particulate Matter in Legionowo, Poland, using residents’ network of low-cost sensors. Along with identifying the hotspots of household-emitted PM, (1) we propose a data quality assurance scheme for PM sensors, (2) suggest an approach for estimating the Relative Humidity-induced uncertainty in the sensors without co-location with reference instruments, and (3) develop an interpretable Machine Learning (ML) model, a Generalized Additive Model (RMSE = 6.16 μg m−3, and R2 = 0.88), for unveiling the underlying relations between PM2.5 levels and other environmental parameters. The results in Legionowo suggest that as air temperature and wind speed increase by 1 °C and 1 km h−1, PM2.5 would respectively decrease by 0.26 μg m−3 and 0.14 μg m−3 while PM2.5 increases by 0.03 μg m−3 as RH increases by 1%.

An Estimation Method for Bias Error of Measurements by Utilizing Process Data, An Incidence Matrix and a Reference Instrument for Data Validation and Reconciliation

Abstract With further applications of AI, IoT, and digital twin technology to plant operation and maintenance, it is becoming increasingly important to ensure data reliability. Data validation and reconciliation (DVR) represents one promising technique to ensure data reliability by minimizing the uncertainty of measurements based on statistics. DVR has been widely applied to nuclear power electrical generation plants in Europe and the U.S. in recent years. The most important input for DVR analysis is measurement uncertainty. In Japan, performance management of nuclear power plants is often done by measuring condensate flowrate. While the uncertainty of other flowmeters is handled by the JIS standard, the condensate flowmeter is specially calibrated every few cycles. This leads to reduction of effectiveness of DVR analysis due to variations in measurement uncertainty management. To overcome this issue, we propose an estimation method for measurement uncertainty by utilizing process data, an incidence matrix between sensors, and a reference instrument. The conventional method proposed in the previous study only treats the random error. The proposed method quantitatively estimates not only random error but also bias error by considering the uncertainty of the reference instrument. Using several benchmark problems, we found that the proposed method was applicable to various flow conditions, including physically fluctuating flow such as that observed in the feedwater flow in nuclear power plants. We anticipate that the proposed method will promote use of DVR analysis in nuclear power plants in Japan.

Long-Term Analysis of Aerosol Concentrations Using a Low-Cost Sensor: Monitoring African Dust Outbreaks in a Suburban Environment in the Canary Islands.

This study presents the results of the long-term monitoring of PM10 and PM2.5 concentrations using a low-cost particle sensor installed in a suburban environment in the Canary Islands. A laser-scattering Nova Fitness SDS011 sensor was operated continuously for approximately three and a half years, which is longer than most other studies using this type of sensor. The impact of African dust outbreaks on the aerosol concentrations was assessed, showing a significant increase in both PM10 and PM2.5 concentrations during the outbreaks. Additionally, a good correlation was found with a nearby reference instrument of the air quality network of the Canary Islands' government. The correlation between the PM10 and PM2.5 concentrations, the effect of relative humidity, and the stability of the sensor were also investigated. This study highlights the potential of this kind of sensor for long-term air quality monitoring with a view to developing extensive and dense low-cost air quality networks that are complementary to official air quality networks.

Laboratory Comparison of Low-Cost Particulate Matter Sensors to Measure Transient Events of Pollution-Part B-Particle Number Concentrations.

Low-cost Particulate Matter (PM) sensors offer an excellent opportunity to improve our knowledge about this type of pollution. Their size and cost, which support multi-node network deployment, along with their temporal resolution, enable them to report fine spatio-temporal resolution for a given area. These sensors have known issues across performance metrics. Generally, the literature focuses on the PM mass concentration reported by these sensors, but some models of sensors also report Particle Number Concentrations (PNCs) segregated into different PM size ranges. In this study, eight units each of Alphasense OPC-R1, Plantower PMS5003 and Sensirion SPS30 have been exposed, under controlled conditions, to short-lived peaks of PM generated using two different combustion sources of PM, exposing the sensors' to different particle size distributions to quantify and better understand the low-cost sensors performance across a range of relevant environmental ranges. The PNCs reported by the sensors were analysed to characterise sensor-reported particle size distribution, to determine whether sensor-reported PNCs can follow the transient variations of PM observed by the reference instruments and to determine the relative impact of different variables on the performances of the sensors. This study shows that the Alphasense OPC-R1 reported at least five size ranges independently from each other, that the Sensirion SPS30 reported two size ranges independently from each other and that all the size ranges reported by the Plantower PMS5003 were not independent of each other. It demonstrates that all sensors tested here could track the fine temporal variation of PNCs, that the Alphasense OPC-R1 could closely follow the variations of size distribution between the two sources of PM, and it shows that particle size distribution and composition are more impactful on sensor measurements than relative humidity.

The European Green Deal: A Useful Framework for Anticipating Change in Companies?

Sergio CanaldaThe restructuring of companies to adapt to a more sustainable production context requires anticipatory measures. These measures must necessarily be articulated through the principle of just transition, offering assistance to workers affected by the restructuring. The European Green Deal aims to promote the transformation of the European Union towards a more sustainable economic model. However, the measures included in the European Union (EU) Fair Transition Recommendation are generic actions without concrete content. When it mentions the need to encourage employee participation in corporate restructuring through information and consultation, the Recommendation refers to the implementation of the Quality Framework on Anticipation of Change and Corporate Restructuring. This paper addresses the adequacy of the Quality Framework to ensure a fair transition in green restructuring processes. In the first section, the interconnection between the EU Fair Transition Recommendation and theQuality Framework is briefly analysed. In the second section, the suitability of the Quality Framework as a reference instrument to guide restructuring processes is examined in two respects: on the one hand, the involvement of workers’ representatives and, on the other hand, the active participation of public authorities through the implementation of other social policies. Green Restructuring, Anticipation of Change, Just Transition, European Green Deal, Quality Framework, Information and Consultation, Social Partners, Public Authorities

Laboratory Performance Evaluation of a Low-Cost Electrochemical Formaldehyde Sensor.

Formaldehyde is a known human carcinogen and an important indoor and outdoor air pollutant. However, current strategies for formaldehyde measurement, such as chromatographic and optical techniques, are expensive and labor intensive. Low-cost gas sensors have been emerging to provide effective measurement of air pollutants. In this study, we evaluated eight low-cost electrochemical formaldehyde sensors (SFA30, Sensirion®, Staefa, Switzerland) in the laboratory with a broadband cavity-enhanced absorption spectroscopy as the reference instrument. As a group, the sensors exhibited good linearity of response (R2 > 0.95), low limit of detection (11.3 ± 2.07 ppb), good accuracy (3.96 ± 0.33 ppb and 6.2 ± 0.3% N), acceptable repeatability (3.46% averaged coefficient of variation), reasonably fast response (131-439 s) and moderate inter-sensor variability (0.551 intraclass correlation coefficient) over the formaldehyde concentration range of 0-76 ppb. We also systematically investigated the effects of temperature and relative humidity on sensor response, and the results showed that formaldehyde concentration was the most important contributor to sensor response, followed by temperature, and relative humidity. The results suggest the feasibility of using this low-cost electrochemical sensor to measure formaldehyde concentrations at relevant concentration ranges in indoor and outdoor environments.

The system for distributed energy resources testing according to the IEEE 1547-2018 standard

PurposeThis paper aims to propose a new approach to testing distributed energy resources (DERs) in compliance with the IEEE 1547-2018 standard and describes a new, integrated testing and validation system.Design/methodology/approachThe system is built on the virtual instrumentation paradigm, using acquisition modules to measure physical quantities, while signal processing, including intensive calculations of required parameters, data processing, manipulation and reporting are performed on a computing device.FindingsIntensive laboratory measurements were performed on a laboratory prototype of a microgrid that emulates DERs. The results obtained using the system described were compared with the measurements obtained by the reference instruments. As all the results match, the usability of the system was verified.Practical implicationsThis approach to the realization of the testing and validation system has obvious advantages compared to the classical instruments and provides significant flexibility in multiple aspects. First, the system described integrates all the functions of different instruments into one measuring system, making the entire testing and validation process significantly cheaper and faster. Second, the implementation of the system is possible on different computing platforms depending on specific needs. Third, the software implementation of the system functions enables simple upgrading and the introduction of new functions or changes to existing ones according to changes in the standard. Finally, the system described is designed to automatically provide reports on compliance with the standard.Originality/valueThis paper emphasizes the advantages of the proposed approach over classical testing. The value of the paper is reflected in the applicability and practical implications of the proposed and described hardware and software technical solutions.

Long-term validation of Aeolus L2B wind products at Punta Arenas, Chile, and Leipzig, Germany

Abstract. Ground-based observations of horizontal winds have been performed at Leipzig (51.35∘ N, 12.43∘ E), Germany, and at Punta Arenas (53.15∘ S, 70.91∘ W), Chile, in the framework of the German initiative EVAA (Experimental Validation and Assimilation of Aeolus observations) with respect to the validation of the Mie and Rayleigh wind products of Aeolus (L2B data). In Leipzig, at the Leibniz Institute for Tropospheric Research (TROPOS), radiosondes have been launched for the Aeolus overpasses on each Friday (ascending orbit) since the middle of May 2019. In Punta Arenas, scanning Doppler cloud radar observations have been performed in the framework of the DACAPO-PESO campaign (dacapo.tropos.de) for more than 3 years from the end of 2018 until the end of 2021 and could be used to validate Aeolus measurements on its ascending and descending orbits. We present two case studies and long‐term statistics of the horizontal winds derived with the ground-based reference instruments compared to Aeolus horizontal line-of-sight (HLOS) winds. The wind products of Aeolus considered are the Mie cloudy and Rayleigh clear products. It was found that the deviation of the Aeolus HLOS winds from the ground reference is usually of Gaussian shape, which allowed the use of the median bias and the scaled median absolute deviation (MAD) for the determination of the systematic and random errors of Aeolus wind products, respectively. The case study from August 2020 with impressive atmospheric conditions at Punta Arenas shows that Aeolus is able to capture strong wind speeds of up to more than 100 m s−1. The long-term validation was performed in Punta Arenas covering the period from December 2018 to November 2021 and in Leipzig from May 2019 until September 2022. This analysis showed that the systematic error of the Aeolus wind products could be significantly lowered during the mission lifetime with the changes introduced into the processing chain (different versions are called baselines). While in the early mission phase, systematic errors of more than 2 m s−1 (absolute values) were observed for both wind types (Mie and Rayleigh), these biases could be reduced with the algorithm improvements, such as the introduction of the correction for temperature fluctuations at the main telescope of Aeolus (M1 temperature correction) with Baseline 09. Hence, since Baseline 10, a significant improvement in the Aeolus data was found, leading to a low systematic error (close to 0 m s−1) and similar values for the midlatitudinal sites in both hemispheres. The random errors for both wind products were first decreasing with an increasing baseline but later increasing again due to performance losses of the Aeolus lidar instrument. Nevertheless, no significant increase in the systematic error in the Aeolus wind products was found. Thus, one can conclude that the uncertainty introduced by the reduced atmospheric return signal received by Aeolus mostly affects the random error. Even when considering all the challenges during the mission, we can confirm the general validity of Aeolus observations during its lifetime. Therefore, this space explorer mission could demonstrate that it is possible to perform active wind observations from space with the applied technique.

The Swedish version of the STarT MSK Tool: cross-cultural adaption, test–retest reliability, and aspects of validity

BackgroundMusculoskeletal disorders (MSDs) are a common reason for seeking primary health care. The STarT Musculoskeletal (MSK) tool is designed to stratify patients suffering from MSDs to risk groups, based on prognostic factors.AimThe aim was to translate and cross-culturally adapt the STarT MSK tool in a Swedish primary health care context through testing of reliability and construct validity.MethodsWe included consecutive patients with MSDs seeking primary care (n = 99). The STarT MSK was translated using international recommendations. Construct validity was investigated by correlation analysis (Spearmans Rho) with the following reference instruments: the Örebro Musculoskeletal Pain Questionnaire (ÖMPQ), the EuroQol 5-dimension (EQ-5D) and the Musculoskeletal Health Questionnaire (MSKHQ). Reliability was tested using test–retest (Intra Class Correlation, ICC2.1) (n = 31). Known-groups validity was calculated with a difference of 10% between risk groups based on how the participants had answered.ResultsThe STarT MSK was successfully translated into Swedish. The participants were grouped into low risk (n = 28), medium risk (n = 60) and high risk (n = 11). The construct validity showed a moderate to high correlation with the ÖMPQ (r = .61), EQ-5D (r = .59) and MSK-HQ (r = .56). All separate items except item 2 and 9 correlated according to predefined hypotheses. Test–retest demonstrated an excellent reliability for the total score (ICC2.1 0.85) (n = 31). The STarT MSK tool was able to differentiate by 10% between the risk groups, based on how the participants had answered.ConclusionThe STarT MSK has been successfully translated and adapted into Swedish and shows acceptable measurement properties regarding test–retest reliability and aspects of validity and seems to be able to discriminate between the proposed risk groups. The tool can therefore be useful in a Swedish primary health care context. A future study needs to determine the tools predictive validity and to investigate if stratification to risk groups leads to a faster recovery and to lower health care costs.

Performance evaluation of QuantStudio 1 plus real-time PCR instrument for clinical laboratory analysis: A proof-of-concept study

ObjectiveThe real-time PCR system is one of the most powerful research tools available in the life sciences field. The aim of this study was to preliminarily evaluate the analytical performance of QuantStudio 1 Plus real-time PCR system (QS 1 plus) for clinical procedures. MethodsThe consistency of QS 1 plus with the reference system in terms of various clinical procedures was evaluated. For qualitative data, the Kappa test was used to analyze the agreement of the results. For the quantitative data, Passing-Bablok regression analysis and Bland-Altman plot analysis were used to assess the concordance between QS 1 plus and the reference instrument. ResultsPassing-Bablok regression showed an excellent agreement between the QS 1 plus and LC 480 systems for HBV DNA quantification (y = 0.928 + 0.970x), whereas Bland-Altman plot analysis showed very small mean deviations between the two systems. The QS 1 plus yielded perfectly consistent results with the reference instrument for methylenetetrahydrofolate reductase (MTHFR) C677T melting curve genotyping analysis, MTHFR C677T genotyping analysis, Norovirus RNA negative/positive analysis, influenza B virus (Flu B) RNA negative/positive analysis, Mycobacterium tuberculosis (MTB) DNA negative/positive analysis, Human Papillomavirus (HPV) genotyping analysis, epidermal growth factor receptor (EGFR) gene mutation analysis. Both the relative quantitative analysis and the relative quantitative analysis (standard curve) confirmed the satisfactory concordance between the QS 1 plus instrument and the ABI 7500 instrument by Passing-Bablok regression analysis (y = 0.180 + 0.817x and y = 0.012 + 1.000x, respectively) and Bland-Altman plot analysis. ConclusionsOur research has proven that QS 1 plus is adaptable to most test procedures in the clinical laboratory. This may provide the basis for its further application.

Psychometric Properties of the Anxiety Sensitivity Index-3 (ASI-3) in Spanish Population.

The Anxiety Sensitivity Index-3 (ASI-3) is the reference instrument for measuring anxiety sensitivity. The psychometric properties of the Spanish version of the ASI-3 have been examined in university students but not in adults from the general population. Whether the ASI-3 subscales provide relevant information has not yet been examined either. The ASI-3's factor structure, internal consistency, temporal stability, and relationship with neuroticism were examined in a Spanish community sample of 919 adults. In two subsamples of participants, the ASI-3 presented a structure of three correlated factors (physical, cognitive, and social concerns) that loaded on a higher-order factor, but the three factors did not explain much item variance. The total scale and subscales of the ASI-3 showed excellent or good indices of internal consistency (alphas and omegas = .81 – .91), and adequate indices of test-retest reliability at two months ( r = .57 – .73) and the relationship with neuroticism and its facets ( r = .19 – .52). The ASI-3 provides reliable, valid measures of anxiety sensitivity in Spanish adults, but its subscales are not very useful beyond the information provided by the total scale.

Characterisation of a self-sustained, water-based condensation particle counter for aircraft cruising pressure level operation

Abstract. Aerosol particle number concentration measurements are a crucial part of aerosol research. Vertical profile measurements and high-altitude/low-pressure performance of the respective instruments become more important for remote sensing validation and a vital tool for the observation of climate variables. This study tests the new, commercially available water condensation particle counter (MAGIC 210-LP) for the deployment at aircraft cruising pressure levels that the European research infrastructure IAGOS (In-service Aircraft for a Global Observing System; http://www.iagos.org, last access: 2 May 2023) is aiming for by operating measurement instrumentation onboard passenger aircraft. We conducted laboratory experiments for conditions to simulate passenger aircraft flight altitude at operation pressure. We demonstrate that this type of water condensation particle counter shows excellent agreement with a butanol-based instrument used in parallel. A Faraday cup aerosol electrometer serves as the reference instrument. Experiments are performed with test aerosol ammonium sulfate and fresh combustion soot at pressure levels ranging from 700 to 200 hPa. For soluble particles like ammonium sulfate, the 50 % detection efficiency cut-off diameter (D50) is around 5 nm and does not differ significantly for all performed experiments. For non-soluble fresh soot particles, the D50 cut-off diameter of approximately 10 nm does not vary substantially as a function of pressure, whereas the 90 % detection efficiency cut-off diameter D90 increases from 19 nm at 700 hPa to 37 nm at 200 hPa. The overall counting efficiency for particles larger than 40 nm reaches 100 % for working pressures of 200 hPa and higher.

Validity, reliability, responsiveness and interpretability ofthe Recap of atopic eczema (RECAP) questionnaire.

Limited research has been conducted on the measurement properties of the Recap of atopic eczema (RECAP) questionnaire, particularly in relation to interpretability. To investigate the validity, reliability, responsiveness and interpretability of the Dutch RECAP in adults with atopic dermatitis (AD). We conducted a prospective study in a Dutch tertiary hospital, recruiting adults with AD between June 2021 and December 2022. Patients completed the RECAP questionnaire, reference instruments and anchor questions at the following three timepoints: baseline, after 1-3 days and after 4-12 weeks. Hypotheses testing was used to investigate single-score validity and change-score validity (responsiveness). To assess reliability, both standard error of measurement (SEMagreement) and intraclass correlation coefficient (ICCagreement) were reported. To assess the interpretability of single scores, bands for eczema control were proposed. To investigate the interpretability of change scores, both smallest detectable change (SDC) and minimally important change (MIC) scores were determined. To estimate the MIC scores, four different anchor-based methods were employed: the mean change method, 95% limit cut-off point, receiver operating characteristic curve and predictive modelling. In total, 200 participants were included (57.5% male sex, mean age 38.5 years). Of the a priori hypotheses, 82% (single-score validity) and 59% (responsiveness) were confirmed. Known-group analyses showed differences in the RECAP scores between patient groups based on disease severity and impairment of the quality of life. The SEMagreement was 1.17 points and the ICCagreement was 0.988. The final banding was as follows: 0-1 (completely controlled); 2-5 (mostly controlled); 6-11 (moderately controlled); 12-19 (a little controlled); 20-28 (not at all controlled). Moreover, a single cut-off point of ≥ 6 was determined to identify patients whose AD is not under control. The SDC was 3.2 points, and the MIC value from the predictive modelling was 3.9 points. Neither floor nor ceiling effects were observed. The RECAP has good single-score validity, moderate responsiveness and excellent reliability. This study fills a gap in the interpretability of the RECAP. Our results indicate a threshold of ≥ 6 points to identify patients whose AD is 'not under control', while an improvement of ≥ 4 points represents a clinically important change. Given its endorsement by the Harmonising Outcome Measures for Eczema initiatives, the results of this study support the integration of RECAP into both routine clinical practice and research settings.

HbA1c comparison and diagnostic efficacy analysis of multi center different glycosylated hemoglobin detection systems

Objective: Compare and analyze the results of the domestic Lanyi AH600 glycated hemoglobin analyzer and other different detection systems to understand the comparability of the detection results of different detectors, and establish the best cut point of Lanyi AH600 determination of haemoglobin A1c (HbA1c) in the diagnosis of diabetes. Methods: Multi center cohort study was adopted. The clinical laboratory departments of 18 medical institutions independently collected test samples from their respective hospitals from March to April 2022, and independently completed comparative analysis of the evaluated instrument (Lanyi AH600) and the reference instrument HbA1c. The reference instruments include four different brands of glycosylated hemoglobin meters, including Arkray, Bio-Rad, DOSOH, and Huizhong. Scatter plot was used to calculate the correlation between the results of different detection systems, and the regression equation was calculated. The consistency analysis between the results of different detection systems was evaluated by Bland Altman method. Consistency judgment principles: (1) When the 95% limits of agreement (95% LoA) of the measurement difference was within 0.4% HbA1c and the measurement score was≥80 points, the comparison consistency was good; (2) When the measurement difference of 95% LoA exceeded 0.4% HbA1c, and the measurement score was≥80 points, the comparison consistency was relatively good; (3) The measurement score was less than 80 points, the comparison consistency was poor. The difference between the results of different detection systems was tested by paired sample T test or Wilcoxon paired sign rank sum test; The best cut-off point of diabetes was analyzed by receiver operating characteristic curve (ROC). Results: The correlation coefficient R2 of results between Lanyi AH600 and the reference instrument in 16 hospitals is≥0.99; The Bland Altman consistency analysis showed that the difference of 95% LoA in Nanjing Maternity and Child Health Care Hospital in Jiangsu Province (reference instrument: Arkray HA8180) was -0.486%-0.325%, and the measurement score was 94.6 points (473/500); The difference of 95% LoA in the Tibetan Traditional Medical Hospital of TAR (reference instrument: Bio-Rad Variant II) was -0.727%-0.612%, and the measurement score was 89.8 points; The difference of 95% LoA in the People's Hospital of Chongqing Liang Jiang New Area (reference instrument: Huizhong MQ-2000PT) was -0.231%-0.461%, and the measurement score was 96.6 points; The difference of 95% LoA in the Taihe Hospital of traditional Chinese Medicine in Anhui Province (reference instrument: Huizhong MQ-2000PT) was -0.469%-0.479%, and the measurement score was 91.9 points. The other 14 hospitals, Lanyi AH600, were compared with 4 reference instrument brands, the difference of 95% LoA was less than 0.4% HbA1c, and the scores were all greater than 95 points. The results of paired sample T test or Wilcoxon paired sign rank sum test showed that there was no statistically significant difference between Lanyi AH600 and the reference instrument Arkray HA8180 (Z=1.665,P=0.096), with no statistical difference. The mean difference between the measured values of the two instruments was 0.004%. The comparison data of Lanyi AH600 and the reference instrument of all other institutions had significant differences (all P<0.001), however, it was necessary to consider whether it was within the clinical acceptable range in combination with the results of the Bland-Altman consistency analysis. The ROC curve of HbA1c detected by Lanyi AH600 in 985 patients with diabetes and 3 423 patients with non-diabetes was analyzed, the area under curve (AUC) was 0.877, the standard error was 0.007, and the 95% confidence interval 95%CI was (0.864, 0.891), which was statistically significant (P<0.001). The maximum value of Youden index was 0.634, and the corresponding HbA1c cut point was 6.235%. The sensitivity and specificity of diabetes diagnosis were 76.2% and 87.2%, respectively. Conclusion: Among the hospitals and instruments currently included in this study, among these four hospitals included Nanjing Maternity and Child Health Care Hospital in Jiangsu Province (reference instrument: Arkray HA8180), Tibetan Traditional Medical Hospital of TAR (reference instrument: Bio-Rad Variant Ⅱ), the People's Hospital of Chongqing Liang Jiang New Area (reference instrument: Huizhong MQ-2000PT), and the Taihe Hospital of traditional Chinese Medicine in Anhui Province (reference instrument: Huizhong MQ-2000PT), the comparison between Lanyi AH600 and the reference instruments showed relatively good consistency, while the other 14 hospitals involved four different brands of reference instruments: Arkray, Bio-Rad, DOSOH, and Huizhong, Lanyi AH600 had good consistency with its comparison. The best cut point of the domestic Lanyi AH600 for detecting HbA1c in the diagnosis of diabetes is 6.235%.

Calibration Transfer Methodology for Cloud Radars Based on Ice Cloud Observations

Abstract This article presents a calibration transfer methodology that can be used between radars of the same or different frequency bands. This method enables the absolute calibration of a cloud radar by transferring it from another collocated instrument with known calibration, by simultaneously measuring vertical ice cloud reflectivity profiles. The advantage is that the added uncertainty in the newly calibrated instrument can converge to the magnitude of the reference instrument calibration. This is achieved by carefully selecting comparable data, including the identification of the reflectivity range that avoids the disparities introduced by differences in sensitivity or scattering regime. The result is a correction coefficient used to compensate measurement bias in the uncalibrated instrument. Calibration transfer uncertainty can be reduced by increasing the number of sampling periods. The methodology was applied between collocated W-band radars deployed during the ICE-GENESIS campaign (Switzerland 2020/21). A difference of 2.2 dB was found in their reflectivity measurements, with an uncertainty of 0.7 dB. The calibration transfer was also applied to radars of different frequency, an X-band radar with unknown calibration and a W-band radar with manufacturer calibration; the difference found was −16.7 dB with an uncertainty of 1.2 dB. The method was validated through closure, by transferring calibration between three different radars in two different case studies. For the first case, involving three W-band radars, the bias found was of 0.2 dB. In the second case, involving two W-band and one X-band radar, the bias found was of 0.3 dB. These results imply that the biases introduced by performing the calibration transfer with this method are negligible.

Laboratory and field evaluation of a low-cost optical particle sizer

Low-cost sensors are widely used to collect high-spatial-resolution particulate matter data that traditional reference monitoring devices cannot. In addition to the mass concentration, the number concentration and size distribution are also fundamental in determining the origin and hazard level of particulate pollution. Therefore, low-cost optical sensors have been improved to establish optical particle sizers (OPSs). In this study, a low-cost OPS, the Nova SDS029, is introduced, and it is evaluated in comparison to two reference instruments—the GRIMM 11-D and the TSI 3330. We first tested the sizing accuracy using polystyrene latex spheres. Then, we assessed the mass and number size distribution accuracy in three application scenarios: indoor smoking, ambient air quality, and mobile monitoring. The evaluations suggest that the low-cost SDS029 rivals research-grade optical sizers in many aspects. For example, (1) the particle diameters obtained with the SDS029 are close to the reference instruments (usually < 10%) in the 0.3–5 µm range; (2) the number of particles and mass concentration are highly correlated (r ≥ 0.99) with the values obtained with the reference instruments; and (3) the SDS029 slightly underestimates the number concentration, but the derived PM2.5 values are closer to monitoring station than the reference instruments. The successful application of the SDS029 in multiple scenarios suggests that a plausible particle size distribution can be obtained in an easy and cost-efficient way. We believe that low-cost OPSs will increasingly be used to map the sources and risk levels of particles at the city scale.

Field evaluation of low-cost electrochemical air quality gas sensors under extreme temperature and relative humidity conditions

Abstract. Modern electrochemical gas sensors hold great potential for improving practices in air quality (AQ) monitoring as their low cost, ease of operation and compact design can enable dense observational networks and mobile measurements. Despite that, however, numerous studies have shown that the performance of these sensors depends on a number of factors (e.g. environmental conditions, sensor quality, maintenance and calibration), thereby adding significant uncertainties in the reported measurements and large discrepancies from those recorded by reference-grade instruments. In this work we investigate the performance of electrochemical sensors, provided by two manufacturers (namely Alphasense and Winsen), for measuring the concentrations of CO, NO2, O3 and SO2. To achieve that we carried out collocated yearlong measurements with reference-grade instruments at a traffic AQ monitoring station in Nicosia, Cyprus, where temperatures ranged from ca. 0 ∘C in the winter to almost 45 ∘C in the summer. The CO sensors exhibit the best performance among all the ones we tested, having minimal mean relative error (MRE) compared to reference instruments (ca. −5 %), although a significant difference in their response was observed before and after the summer period. At the other end of the spectrum, the SO2 sensors reported concentration values that were at least 1 order of magnitude higher than the respective reference measurements (with MREs being more than 1000 % for Alphasense and almost 400 % for Winsen throughout the entire measurement period), which can be justified by the fact that the concentrations of SO2 at our measuring site were below their limit of detection. In general, variabilities in the environmental conditions (i.e. temperature and relative humidity) appear to significantly affect the performance of the sensors. When compared with reference instruments, the CO and NO2 electrochemical sensors provide measurements that exhibit increasing errors and decreasing correlations as temperature increases (from below 10 to above 30 ∘C) and RH decreases (from &gt;75 % to below 30 %). Interestingly, the performance of the sensors was affected irreversibly during the hot summer period, exhibiting different responses before and after that, resulting in a signal deterioration that was more than twice that reported by the manufacturers. With the exception of the Alphasense NO2 sensor, all low-cost sensors (LCSs) exhibited measurement uncertainties that were much higher, even at the beginning of our measurement period, compared to those required for qualifying the sensors for indicative air quality measurements according to the respective European Commission (EC) Directive. Overall, our results show that the response of all LCSs is strongly affected by the environmental conditions, warranting further investigations on how they are manufactured, calibrated and employed in the field.