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1.
Sensors (Basel) ; 21(12)2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34201377

RESUMO

Over the last decade, manufacturers have come forth with cost-effective sensors for measuring ambient and indoor particulate matter concentration. What these sensors make up for in cost efficiency, they lack in reliability of the measured data due to their sensitivities to temperature and relative humidity. These weaknesses are especially evident when it comes to portable or mobile measurement setups. In recent years many studies have been conducted to assess the possibilities and limitations of these sensors, however mostly restricted to stationary measurements. This study reviews the published literature until 2020 on cost-effective sensors, summarizes the recommendations of experts in the field based on their experiences, and outlines the quantile-mapping methodology to calibrate low-cost sensors in mobile applications. Compared to the commonly used linear regression method, quantile mapping retains the spatial characteristics of the measurements, although a common correction factor cannot be determined. We conclude that quantile mapping can be a useful calibration methodology for mobile measurements given a well-elaborated measurement plan assures providing the necessary data.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Calibragem , Monitoramento Ambiental , Material Particulado/análise , Reprodutibilidade dos Testes
2.
Sensors (Basel) ; 21(12)2021 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-34199170

RESUMO

Visual inspection is an important task in manufacturing industries in order to evaluate the completeness and quality of manufactured products. An autonomous robot-guided inspection system was recently developed based on an offline programming (OLP) and RGB-D model system. This system allows a non-expert automatic optical inspection (AOI) engineer to easily perform inspections using scanned data. However, if there is a positioning error due to displacement or rotation of the object, this system cannot be used on a production line. In this study, we developed an automated position correction module to locate an object's position and correct the robot's pose and position based on the detected error values in terms of displacement or rotation. The proposed module comprised an automatic hand-eye calibration and the PnP algorithm. The automatic hand-eye calibration was performed using a calibration board to reduce manual error. After calibration, the PnP algorithm calculates the object position error using artificial marker images and compensates for the error to a new object on the production line. The position correction module then automatically maps the defined AOI target positions onto a new object, unless the target position changes. We performed experiments that showed that the robot-guided inspection system with the position correction module effectively performed the desired task. This smart innovative system provides a novel advancement by automating the AOI process on a production line to increase productivity.


Assuntos
Algoritmos , Calibragem , Rotação
3.
Molecules ; 26(13)2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-34206357

RESUMO

In the current work, a simple, economical, accurate, and precise HPLC method with UV detection was developed to quantify Favipiravir (FVIR) in spiked human plasma using acyclovir (ACVR) as an internal standard in the COVID-19 pandemic time. Both FVIR and ACVR were well separated and resolved on the C18 column using the mobile phase blend of methanol:acetonitrile:20 mM phosphate buffer (pH 3.1) in an isocratic mode flow rate of 1 mL/min with a proportion of 30:10:60 %, v/v/v. The detector wavelength was set at 242 nm. Maximum recovery of FVIR and ACVR from plasma was obtained with dichloromethane (DCM) as extracting solvent. The calibration curve was found to be linear in the range of 3.1-60.0 µg/mL with regression coefficient (r2) = 0.9976. However, with acceptable r2, the calibration data's heteroscedasticity was observed, which was further reduced using weighted linear regression with weighting factor 1/x. Finally, the method was validated concerning sensitivity, accuracy (Inter and Intraday's % RE and RSD were 0.28, 0.65 and 1.00, 0.12 respectively), precision, recovery (89.99%, 89.09%, and 90.81% for LQC, MQC, and HQC, respectively), stability (% RSD for 30-day were 3.04 and 1.71 for LQC and HQC, respectively at -20 °C), and carry-over US-FDA guidance for Bioanalytical Method Validation for researchers in the COVID-19 pandemic crisis. Furthermore, there was no significant difference for selectivity when evaluated at LLOQ concentration of 3 µg/mL of FVIR and relative to the blank.


Assuntos
Amidas/análise , Amidas/sangue , Antivirais/análise , Antivirais/sangue , Bioensaio/métodos , COVID-19/tratamento farmacológico , Cromatografia Líquida de Alta Pressão/métodos , Extração Líquido-Líquido/métodos , Pirazinas/análise , Pirazinas/sangue , Aciclovir/análise , Aciclovir/sangue , COVID-19/sangue , Calibragem , Estabilidade de Medicamentos , Congelamento , Humanos , Padrões de Referência , Reprodutibilidade dos Testes , Solventes/química
4.
Molecules ; 26(12)2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34205805

RESUMO

Exhaled breath analysis for early disease detection may provide a convenient method for painless and non-invasive diagnosis. In this work, a novel, compact and easy-to-use breath analyzer platform with a modular sensing chamber and direct breath sampling unit is presented. The developed analyzer system comprises a compact, low volume, temperature-controlled sensing chamber in three modules that can host any type of resistive gas sensor arrays. Furthermore, in this study three modular breath analyzers are explicitly tested for reproducibility in a real-life breath analysis experiment with several calibration transfer (CT) techniques using transfer samples from the experiment. The experiment consists of classifying breath samples from 15 subjects before and after eating a specific meal using three instruments. We investigate the possibility to transfer calibration models across instruments using transfer samples from the experiment under study, since representative samples of human breath at some conditions are difficult to simulate in a laboratory. For example, exhaled breath from subjects suffering from a disease for which the biomarkers are mostly unknown. Results show that many transfer samples of all the classes under study (in our case meal/no meal) are needed, although some CT methods present reasonably good results with only one class.


Assuntos
Técnicas Biossensoriais/métodos , Testes Respiratórios/métodos , Expiração/fisiologia , Sistema Respiratório/fisiopatologia , Adolescente , Biomarcadores/metabolismo , Calibragem , Humanos , Sistema Respiratório/metabolismo
5.
Se Pu ; 39(4): 391-398, 2021 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-34227759

RESUMO

Urine is an important source of biomolecular information for metabolomic studies. However, the acquisition of high-quality metabolomic datasets or reliable biomarkers from urine is difficult owing to the large variations in the concentrations of endogenous metabolites in the biofluid, which are caused by diverse factors such as water consumption, drugs, and diseases. Thus, normalization or calibration is essential in urine metabolomics for eliminating such deviations. The urine osmolality (Π), which is a direct measure of the total urinary solute concentration and is not affected by circadian rhythms, diet, gender, and age, is often considered the gold standard for estimation of the urine concentration. In this study, a pre-data acquisition calibration strategy based on osmolality was investigated for its feasibility to overcome sample concentration variability. Before data acquisition, the product of the osmolality×injection volume of all samples was set to be equivalent through the uses of a customized injection volume or dilution. After ultra performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) analysis of the sample, the raw dataset was normalized to the total ion abundance or total useful MS signals (MSTUS) to achieve further calibration. The osmolality of each urine sample was determined with a freezing-point depression osmometer. For the instrumental analysis, a Vanquish UPLC system coupled to a Q-Exactive Plus HRMS device was used for metabolite analysis and accurate mass measurement. Full-scan mass spectra were acquired in the range of m/z 60-900, and the MS/MS experiments were conducted in "Top5" data-dependent mode. A Waters UPLC column (100 mm×2.1 mm, 1.8 µm) was used for chromatography separation. The raw data were imported into Progenesis QI software for peak picking, alignment, deconvolution, and normalization. SIMCA-P software was used for the principal component analysis (PCA) and orthogonal partial least-squares discrimination analysis (OPLS-DA). This strategy was first applied to sequentially diluted urine samples, where three frequently used normalization methods were compared. In the identical injection volume experiment, the points were scattered and showed relevant distribution according to the dilution multiple in the plot of PCA scores. There was little improvement after normalization to either the total ion abundance or MSTUS. In the customized injection volume experiment, the urine samples derived from the same source showed ideal clustering. With total ion abundance and MSTUS normalization, the dataset was further improved in the PCA model fitting and prediction. As a result, there were more peaks with a peak area RSD of <30%, which indicated better parallelism. The diluted urine solutions had higher Spearman's coefficient values with their sample source than those without calibration, which suggested less intra-group differences. The strategy was further validated using data from a metabolomic study of children with congenital hydronephrosis and healthy controls. As a concentration estimator, osmolality showed better linear correlation with the mass signal and was less influenced by physiological or pathological factors, thus obtaining broader application and more accurate results than creatinine. The concentration variability was effectively eliminated after customized dilution calibration and showed a more obvious clustering effect in the PCA score plot. The OPLS-DA-based statistical model used to identify discriminate metabolites was improved, with less chance of overfitting. In conclusion, the calibration strategy based on osmolality combined with total ion abundance or MSTUS normalization significantly overcame the problem of urine concentration variability, eliminated intra-group differences, and possessed better parallelism, thus giving better clustering effects in PCA or OPLS-DA and higher reliability of the statistical model. The results of this study provide guidance and a reference for future metabolomic studies on urine.


Assuntos
Hidronefrose/urina , Metabolômica , Urinálise , Calibragem , Criança , Cromatografia Líquida de Alta Pressão , Humanos , Hidronefrose/congênito , Concentração Osmolar , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem
6.
Sensors (Basel) ; 21(13)2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34282796

RESUMO

Measuring the mass flow of sugarcane in real-time is essential for harvester automation and crop monitoring. Data integration from multiple sensors should be an alternative to receive more reliable, accurate, and valuable predictions than data delivered by a single sensor. In this sense, the objective was to evaluate if the fusion of different sensors installed in a sugarcane harvester improves the mass flow prediction accuracy. A harvester was experimentally instrumented, and neural network models integrated sensor data along the harvester to perform the self-calibration of these sensors and estimate the mass flow. Nonlinear autoregressive networks with exogenous input (NARX) and multiple linear regression (MLR) models were compared to predict the mass flow. The prediction with the NARX showed a significant superiority over MLR. MLR decreases the estimated mass flow variability in the harvester. NARX with multi-sensor data has an RMSE of 0.3 kg s-1, representing a MAPE of 0.7%. The fusion of sensor signals improves prediction accuracy, with higher performance than studies with approaches that used a single sensor. The mass flow approach with multiple sensors is a potential approach to replace conventional yield monitors. The system generates accurate data with high sample density within sugarcane rows.


Assuntos
Saccharum , Calibragem , Redes Neurais de Computação , Fenômenos Físicos
7.
Sensors (Basel) ; 21(13)2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34283135

RESUMO

There are generally complex features with large curvature or narrow space on surfaces of complicated tiny parts, which makes high-precision measurements of their three-dimensional (3D) overall profiles a long-lasting industrial problem. This paper proposes a feasible measurement solution to this problem, by designing a cradle-type point-scanning five-axis measurement system. All the key technology of this system is also studied from the system construction to the actual measurement process, and the measurement accuracy is improved through error calibration and compensation. Finally, the feasibility is proved by engineering realization. The measurement capability of the system is verified by measuring workpieces such as cross cylinders and microtriangular pyramids.


Assuntos
Imageamento Tridimensional , Calibragem
8.
Sensors (Basel) ; 21(13)2021 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-34199010

RESUMO

In all ultrasonic material evaluation methods, transducers and sensors play a key role of mechanoelectrical conversion. Their transduction characteristics must be known quantitatively in designing and implementing successful structural health monitoring (SHM) systems. Yet, their calibration and verification have lagged behind most other aspects of SHM system development. This study aims to extend recent advances in quantifying the transmission and receiving sensitivities to normally incident longitudinal waves of ultrasonic transducers and acoustic emission sensors. This paper covers extending the range of detection to lower frequencies, expanding to areal and multiple sensing methods and examining transducer loading effects. Using the refined transmission characteristics, the receiving sensitivities of transducers and sensors were reexamined under the conditions representing their actual usage. Results confirm that the interfacial wave transmission is governed by wave propagation theory and that the receiving sensitivity of resonant acoustic emission sensors peaks at antiresonance.


Assuntos
Transdutores , Ultrassom , Acústica , Calibragem , Monitorização Fisiológica
9.
Spectrochim Acta A Mol Biomol Spectrosc ; 262: 120116, 2021 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-34217146

RESUMO

Acetylsalicylic acid and omeprazole were recently formulated by the new FDA-approved drug Yosprala ® Tablets. This novel combination was prescribed to reduce the risk of myocardial infarction in patients who were at risk for developing peptic ulcer while taking acetylsalicylic acid. In the current work, two different high precision sensitive fluorescence spectroscopic methods were developed for quantitative analysis of the above drugs in pharmaceutical dosage form and spiked human plasma. Acetylsalicylic acid was quantitatively analyzed due to its unique native fluorescence nature. The fluorescence emission of acetylsalicylic acid was quantitatively determined at 404 nm after excitation at 296 nm without any interference from omeprazole. Omeprazole, which has a free terminal secondary amino group, reacted with 4-chloro-7-nitrobenzo-2-oxa-1, 3-diazole (NBD-Cl) by a nucleophilic substitution mechanism to form a highly fluorescent dark yellow fluorophore. Omeprazole was quantitatively analyzed by measuring the emission fluorescence intensity of the dark yellow fluorophore at 535 nm after excitation at 465 nm. Various parameters affecting the described methods were carefully checked and optimized. The calibration curves were found to be linear over the concentration range of 50-1600 ng/ml for acetylsalicylic and 30-2000 ng/ml for omeprazole. The proposed methods were successfully applied to the quantitative analysis of the two drugs in the pharmaceutical dosage form Yosprala ® and in spiked human plasma.


Assuntos
Aspirina , Omeprazol , Calibragem , Humanos , Espectrometria de Fluorescência , Comprimidos
10.
Se Pu ; 39(5): 494-509, 2021 May.
Artigo em Chinês | MEDLINE | ID: mdl-34227334

RESUMO

QuEChERS pretreatment combined with gas chromatography-quadrupole time-of-flight mass spectrometry (GC-Q-TOF/MS) has been investigated for application in screening 244 pesticide residues in chilli. Fresh chilli samples were extracted with acetonitrile, and dried chilli samples were extracted using an acetonitrile/acetic acid (99∶1, v/v) mixture. The two extraction solvents were stored at -20 ℃. After salting out and cleaning by dispersive solid phase extraction (dSPE), heptachlor epoxide B was added as an internal standard, and the resulting residues were dissolved in 1.00 mL acetone. The dissolved sample solution was loaded onto an HP-5MS UI column (30 m×0.25 mm, 0.25 µm) and eluted by GC-Q-TOF/MS with a programmable temperature vaporizer and splitless injection in the full-scan mode. The compensation effects of the analytical protectant (AP) and matrix-matched calibration method on the matrix effect were established. AP could be used in the fresh chilli matrix to compensate for matrix effects, but it was not effective in the dried chilli matrix. The matrix-matched calibration method was effective in both matrices, which was selected for the quantification of pesticide residues in the samples. Because of the existence of the isomers of one compound and the same characteristic ions of different compounds, analyte detection was based on a flexible retention time deviation of ±0.25 min and accurate mass deviation of ±20×10 -6. Screening was performed by the software in the automatic matching mode. Compound identification and quantitation were based on a database and calibration curve established with reference materials. Suspicious samples were subjected to manual analysis. Quantitative analysis of 244 pesticide residues in fresh chilli and 222 pesticide residues in dried chilli was performed. The results showed that the developed database and method can provide a reference for the high-throughput screening and quantitation of fresh and dried chilli. Different levels of pesticides were added to the blank chilli samples, and the addition level corresponding to a signal-to-noise ratio (S/N) of 10 was used as the limit of quantification (LOQ). The LOQs of 44 pesticides with a maximum residue limit (MRL) ≤0.05 mg/kg in fresh chilli did not exceed 0.010 mg/kg. The linear ranges of these 44 pesticides were 0.01-1.00 mg/L. At spiked levels of the LOQ and 2.5 times the LOQ, the ratios of the 44 pesticides with recoveries of 60% to 120% were 88.64% and 100%, respectively. The LOQs of 200 pesticides with MRLs ≥0.05 mg/kg or without MRLs in fresh chilli did not exceed 0.025 mg/kg. The linear ranges of these 200 pesticides were 0.05-1.00. At spiked levels of the LOQ, twice the LOQ, and 10 times the LOQ, the ratios of the 200 pesticides with recoveries of 60% to 120% were 49.50%, 87.00%, and 89.50%, respectively. The linear correlation coefficients (r 2) of the 244 pesticides in fresh chilli were greater than 0.99. The LOQs of 222 pesticides in dried chilli were less than 0.15 mg/kg, and the linear ranges were 0.04-1.00 mg/L. The ratios of these 222 pesticides with r 2 greater than 0.99 was 95.46%. At spiked levels of the LOQ, twice the LOQ and 10 times the LOQ in dried chilli, the ratio of the 222 pesticides with recoveries of 60% to 120% were 72.52%, 73.42%, and 81.53%, respectively. The established screening and confirmation method was used to analyze 12 fresh chilli samples and 14 dried chilli samples. Eight pesticides were found in nine fresh chilli samples and three dried chilli samples, all of which were confirmed to be positive after manual identification. The concentrations of these pesticides were lower than the MRLs required by GB 2763-2019: National Food Safety Standard Maximum Residue Limits for Pesticides in Food. The results demonstrate that the established method is rapid, easy to execute, efficient, and reliable. It can be used for the high-throughput screening and quantitation of pesticide residues in fresh and dried chilli.


Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Resíduos de Praguicidas , Calibragem , Cromatografia Gasosa-Espectrometria de Massas , Carne/análise , Resíduos de Praguicidas/análise , Extração em Fase Sólida
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 262: 120107, 2021 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-34245968

RESUMO

An approach for measuring water concentration in oil, based on the use of CuSO4 particles and infrared spectroscopy, is described. The particles interact with both dissolved water and water droplets to form the monohydrate, CuSO4·H2O. These particles are collected on an infrared transparent membrane and then an infrared spectrum in transmission mode is recorded. Strong interaction of the water with the CuSO4 shifts and intensifies the water bending mode to produce a unique band at 1743 cm-1. The method provided values which are equivalent to those measured by Karl Fischer titration over the range of 10 to 3500 mg L-1 with a linearity R2 value of > 0.99 and an average %RSD for all measurements was 6%. No matrix specific calibrations are required.


Assuntos
Sulfato de Cobre , Água , Calibragem , Pós , Espectrofotometria Infravermelho
12.
Bioinformatics ; 37(Suppl_1): i102-i110, 2021 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-34252953

RESUMO

MOTIVATION: Precise time calibrations needed to estimate ages of species divergence are not always available due to fossil records' incompleteness. Consequently, clock calibrations available for Bayesian dating analyses can be few and diffused, i.e. phylogenies are calibration-poor, impeding reliable inference of the timetree of life. We examined the role of speciation birth-death (BD) tree prior on Bayesian node age estimates in calibration-poor phylogenies and tested the usefulness of an informative, data-driven tree prior to enhancing the accuracy and precision of estimated times. RESULTS: We present a simple method to estimate parameters of the BD tree prior from the molecular phylogeny for use in Bayesian dating analyses. The use of a data-driven birth-death (ddBD) tree prior leads to improvement in Bayesian node age estimates for calibration-poor phylogenies. We show that the ddBD tree prior, along with only a few well-constrained calibrations, can produce excellent node ages and credibility intervals, whereas the use of an uninformative, uniform (flat) tree prior may require more calibrations. Relaxed clock dating with ddBD tree prior also produced better results than a flat tree prior when using diffused node calibrations. We also suggest using ddBD tree priors to improve the detection of outliers and influential calibrations in cross-validation analyses.These results have practical applications because the ddBD tree prior reduces the number of well-constrained calibrations necessary to obtain reliable node age estimates. This would help address key impediments in building the grand timetree of life, revealing the process of speciation and elucidating the dynamics of biological diversification. AVAILABILITY AND IMPLEMENTATION: An R module for computing the ddBD tree prior, simulated datasets and empirical datasets are available at https://github.com/cathyqqtao/ddBD-tree-prior.


Assuntos
Evolução Molecular , Fósseis , Teorema de Bayes , Calibragem , Especiação Genética , Filogenia
13.
Sensors (Basel) ; 21(14)2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34300448

RESUMO

This paper summarized the research status, imaging model, systems calibration, distortion correction, and panoramic expansion of panoramic vision systems, pointed out the existing problems and put forward the prospect of future research. According to the research status of panoramic vision systems, a panoramic vision system with single viewpoint of refraction and reflection is designed. The systems had the characteristics of fast acquisition, low manufacturing cost, fixed single-view imaging, integrated imaging, and automatic switching depth of field. Based on these systems, an improved nonlinear optimization polynomial fitting method is proposed to calibrate the monocular HOVS, and the binocular HOVS is calibrated with the Aruco label. This method not only improves the robustness of the calibration results, but also simplifies the calibration process. Finally, a real-time method of panoramic map of multi-function vehicle based on vcam is proposed.


Assuntos
Algoritmos , Tecnologia , Calibragem
14.
Sensors (Basel) ; 21(14)2021 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-34300517

RESUMO

Good air quality is essential for both human beings and the environment in general. The three most harmful air pollutants are nitrogen dioxide (NO2), ozone (O3) and particulate matter. Due to the high cost of monitoring stations, few examples of this type of infrastructure exist, and the use of low-cost sensors could help in air quality monitoring. The cost of metal-oxide sensors (MOS) is usually below EUR 10 and they maintain small dimensions, but their use in air quality monitoring is only valid through an exhaustive calibration process and subsequent precision analysis. We present an on-field calibration technique, based on the least squares method, to fit regression models for low-cost MOS sensors, one that has two main advantages: it can be easily applied by non-expert operators, and it can be used even with only a small amount of calibration data. In addition, the proposed method is adaptive, and the calibration can be refined as more data becomes available. We apply and evaluate the technique with a real dataset from a particular area in the south of Spain (Granada city). The evaluation results show that, despite the simplicity of the technique and the low quantity of data, the accuracy obtained with the low-cost MOS sensors is high enough to be used for air quality monitoring.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Calibragem , Cidades , Monitoramento Ambiental , Humanos , Óxidos , Material Particulado/análise , Espanha
15.
Sensors (Basel) ; 21(14)2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34300567

RESUMO

In an autonomous vehicle, the lane following algorithm is an important component, which is a basic function of autonomous driving. However, the existing lane following system has a few shortcomings: first, the control method it adopts requires an accurate system model, and different vehicles have different parameters, which needs a lot of parameter calibration work. The second is that it may fail on road sections where the lateral acceleration requirements of vehicles are large, such as large curves. Third, its decision-making system is defined based on rules, which has disadvantages: it is difficult to formulate; human subjective factors cannot guarantee objectivity; coverage is difficult to guarantee. In recent years, the deep deterministic policy gradient (DDPG) algorithm has been widely used in the field of autonomous driving due to its strong nonlinear fitting ability and generalization performance. However, the DDPG algorithm has overestimated state action values and large cumulative errors, low training efficiency and other issues. Therefore, this paper improves the DDPG algorithm based on the double critic networks and priority experience replay mechanism. Then this paper proposes a lane following method based on this algorithm. Experiment shows that the algorithm can achieve excellent following results under various road conditions.


Assuntos
Acidentes de Trânsito , Condução de Veículo , Algoritmos , Calibragem , Humanos , Políticas
16.
Sensors (Basel) ; 21(14)2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34300568

RESUMO

We present fluorescent Janus hydrogel microbeads for continuous glucose sensing with pH calibration. The Janus hydrogel microbeads, that consist of fluorescent glucose and pH sensors, were fabricated with a UV-assisted centrifugal microfluidic device. The microbead can calibrate the pH values of its surroundings and enables accurate measurements of glucose within various pH conditions. As a proof of concept, we succeeded in obtaining the accurate value of glucose concentration in a body-fluid-like sample solution. We believe that our fluorescent microbeads, with pH calibration capability, could be applied to fully implantable sensors for continuous glucose monitoring.


Assuntos
Automonitorização da Glicemia , Hidrogéis , Glicemia , Calibragem , Glucose , Concentração de Íons de Hidrogênio , Microesferas
17.
Sensors (Basel) ; 21(14)2021 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-34300610

RESUMO

This work presents a microwave reflectometry-based system for monitoring large concrete structures (during the curing process and also while the structure is in use), through the combined use of punctual and diffused sensing elements. In particular, the adoption of punctual probes on a reference concrete specimen allows the development of an innovative and accurate calibration procedure, useful to obtain the value of the water content on a larger structure made of the same material. Additionally, a wire-like diffused sensing element can be permanently embedded in buildings and used to monitor the structure along the entire length of the sensing element. The adopted diffused sensing element can be used not only to detect dielectric variation during the curing process, but also throughout the service life of the structure. The combined use of punctual and diffused sensing elements represents an important innovation from a procedural point of view, able to provide detailed and quantitative information on the health status of the structure both during and after construction.


Assuntos
Micro-Ondas , Água , Calibragem , Difusão , Monitorização Fisiológica
18.
Sensors (Basel) ; 21(14)2021 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-34300664

RESUMO

The real-time monitoring of the flow environment parameters, such as flow velocity and direction, helps to accurately analyze the effect of water scour and provide technical support for the maintenance of pier and abutment foundations in water. Based on the principle of the Fiber Brag Grating sensor, a sensor for monitoring the flow velocity and direction in real-time is designed in this paper. Meanwhile, the theoretical calculation formulas of flow velocity and direction are derived. The structural performance of the sensor is simulated and analyzed by finite element analysis. The performance requirements of different parts of the sensor are clarified. After a sample of the sensor is manufactured, calibration experiments are conducted to verify the function and test the accuracy of the sensor, and the experimental error is analyzed. The experimental results indicate that the sensor designed in this paper achieves a high accuracy for the flow with a flow velocity of 0.05-5 m/s and the flow velocity monitoring error is kept within 7%, while the flow direction monitoring error is kept within 2°. The sensor can meet the actual monitoring requirements of the structures in water and provide reliable data sources for water scour analysis.


Assuntos
Análise de Elementos Finitos , Calibragem , Fenômenos Físicos
19.
Sensors (Basel) ; 21(12)2021 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-34208225

RESUMO

Global localization is a fundamental ability for mobile robots. Considering the limitation of single type of sensor, fusing measurements from multiple sensors with complementary properties is a valuable task for study. In this paper, we propose a decoupled optimization-based framework for global-local sensor fusion, which fuses the intermittent 3D global positions and high-frequent 6D odometry poses to infer the 6D global localization results in real-time. The fusion process is formulated as estimating the relative transformation between global and local reference coordinates, translational extrinsic calibration, and the scale of the local pose estimator. We validate the full observability of the system under general movements, and further analyze the degenerated movement patterns where some related system state would be unobservable. A degeneration-aware sensor fusion method is designed which detects the degenerated directions before optimization, and adds constraints specifically along these directions to relieve the effect of the noise. The proposed degeneration-aware global-local sensor fusion method is validated in both simulation and real-world datasets with different sensor configurations, and shows its effectiveness in terms of accuracy and robustness compared with other decoupled sensor fusion methods for global localization.


Assuntos
Algoritmos , Movimento , Calibragem , Simulação por Computador
20.
Environ Monit Assess ; 193(8): 531, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34322768

RESUMO

Multivariate calibration based on partial least squares, random forest, and support vector machine methods, combined with the MissForest imputation algorithm, was used to understand the interaction between ozone and nitrogen oxides, carbon monoxide, wind speed, solar radiation, temperature, relative humidity, and others, the data of which were collected by air quality monitoring stations in the metropolitan area of Rio de Janeiro in four distinct sites between, 2014 and, 2018. These techniques provide an easy and feasible way of modeling and analyzing air pollutants and can be used when coupled with other methods. The results showed that random forest and support vector machine chemometric techniques can be used in modeling and predicting tropospheric ozone concentrations, with a coefficient of determination for making predictions up to 0.92, a root-mean square error of calibration between 4.66 and 27.15 µg m-3, and a root-mean square error of prediction between 4.17 and 22.45 µg m-3, depending on the air quality monitoring stations and season.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Ozônio , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Brasil , Calibragem , Monitoramento Ambiental , Ozônio/análise
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