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1
Markuze, Yu I., Anh Cuong Le, Thi Thu Nguyen et Hai Nam Dinh. « Monitoring coarse measurement errors and initial data ». Geodesy and Cartography 937, no 7 (20 août 2018) : 11–16. http://dx.doi.org/10.22389/0016-7126-2018-937-7-11-16.
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Rough errors are a consequence of the observer’s miscalculations, device malfunctions, their displacements at the time of measurement, incorrect measurement techniques chosen, rapid and sharp deterioration of external conditions and other causes. That is why, one of the problems in the theory of mathematical processing geodetic measurements is culling measurements containing gross errors. In the last two decades received recursion equalization has been widespread. It enables evaluating the unknown while new measurements are added to the network and measurements with gross errors are deleted [3, 4]. In the article, a complementary recurrent equalization is developed. It is original, convenient and recommended for wide application in production.
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P, Tuccimei. « mproving Gas Permeability Measurements for Environmental Monitoring and Management ». Open Access Journal of Waste Management & ; Xenobiotics 2, no 2 (2019) : 1–11. http://dx.doi.org/10.23880/oajwx-16000123.
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Intrinsic permeability is a crucial parameter to interpret soil gas data recorded from monitoring stations in different environmental settings. It is also fundamental for environmental management and pollution reme diation. An improved version of a permeameter (PRM3) recently developed for environmental applications is presented and calibrated against a reference instrument (RADON - JOK produced by RADON v.o.s.). The innovations of this prototype are: i) the absence of the flow meter, and ii) a membrane pump in place of a rotary vane device. Proper calculation of the permeability from Darcy’s law is provided, as well as a modified formula for permeability determination in volcanic areas. Actually, soil gas viscosity and permeability are affected by changing gas temperature and composition. The effects of these two parameters on soil gas viscosity and permeability are also displayed. The second part of the paper shows the employ of permeability measurements in environment al monitoring. The aim of these field - works was the study of lateral and vertical variability of soil permeability at a very small scale (step of 0.25 m) and the effect of intrinsic permeability on gas transport through the soil and on gas concentration al ong depth profiles . We chose 2 different test sites: Valle della Caffarella (Roma, Italy) and Solfatara Volcano (Pozzuoli, Italy) areas. A specific protocol, designed to check any interference among permeability measurements carried out at very close dista nces demonstrated that no disturbance is occurring. Intrinsic permeability profiles resulted to be good proxy indicators for the degassing style of the two areas. In both cases, it gave important hints to interpret environmental data and help in the manage ment of the sites.
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Waidson, Mike. « HDTV Measurements and Monitoring ». SMPTE Journal 111, no 2 (février 2002) : 71–79. http://dx.doi.org/10.5594/j16390.
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Hujo, Ľ., Z. Tkáč, J. Tulík, J. Kosiba, D. Uhrinová et M. Jánošová. « Monitoring of operation loading of three-point linkage during ploughing ». Research in Agricultural Engineering 62, No. 1 (30 mars 2016) : 24–29. http://dx.doi.org/10.17221/10/2015-rae.
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The research was focused on operational measurements of tractor plough tools and their subsequent utilisation and simulation under laboratory conditions by a hydrostatic simulator. In this field, theoretical and experimental works were focused on tractors, whereby the proposal of laboratory test arose out of the loading characteristics of the three-point linkage of the tractor. These characteristics were obtained from the agricultural tractor’s operation in plough aggregation. Measurements were performed with the following tools: tractor with carrier-mounted four-mouldboard plough PH1-435 and tractor with Kuhn plough manufactured by. The subject of these measurements was to obtain the time courses of forces and pressures in the hydraulic system of the three-point linkage during ploughing with carrier-mounted and semi-mounted ploughs. For objective comparison of the obtained results during experimental measurements, we determined the characteristics of measurement conditions focused on physical and mechanical properties of the soil – bulk density, moisture, penetrometer resistance and slide strength of the soil.
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Menzel, Tobias, et Wolfgang Potthast. « Validation of a Unique Boxing Monitoring System ». Sensors 21, no 21 (20 octobre 2021) : 6947. http://dx.doi.org/10.3390/s21216947.
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Much development work and scientific research has been conducted in recent years in the field of detecting human activity and the measurement of biomechanical performance parameters using portable sensor technologies, so-called wearable systems. Despite the fact that boxers participating in one of the most vigorous and complex disciplines of all sports, it is one of the disciplines where no noteworthy, advanced performance analytic tools are used for training or for competition purposes worldwide. This research aimed to develop and validate a comprehensive punch performance sensor system for the measurement and analysis of biomechanical parameters in the sport of boxing. A comprehensive validation study on linear regression was conducted following the development of the sensor system, between the gold standard of a Kistler force plate and Vicon motion capture system, to compare sensor-derived measurements with the gold standard-derived measurements. The developed sensor system demonstrated high accuracies ranging from R2 = 0.97 to R2 = 0.99 for punch force, acceleration, velocity and punch-time data. The validation experiments conducted demonstrated the significant accuracy of the sensor-derived measurements for predicting boxing-specific biomechanical movement parameters while punching in field use. Thus, this paper presents a unique sensor system for comprehensive measurements of biomechanical parameters using the developed mobile measurement system in the field of combat sports
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Kapalo, Peter, Orest Voznyak, Vasyl Zhelykh, Hanna Klymenko et Khrystyna Myroniuk. « AIR QUALITY MONITORING IN A SELECTED CLASSROOM ». Theory and Building Practice 2022, no 1 (20 juin 2022) : 71–79. http://dx.doi.org/10.23939/jtbp2022.01.071.
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As part of the research entitled "Experimental determination of the optimal amount of air in a selected room in Ukraine based on measurements of carbon dioxide concentration", an experimental measurement was performed in a selected school room in Ukraine. The aim of the experimental measurement was to determine the course of air temperature, relative humidity and carbon dioxide concentration during the teaching process. From the carbon dioxide concentration curves, it is possible to calculate the required ventilation intensity in the room. This article documents the results of measuring the air temperature and the carbon dioxide concentration in the room, as well as the reactions of people in the room to the air quality.
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Hicks, J. M. « In situ monitoring. » Clinical Chemistry 31, no 12 (1 décembre 1985) : 1931–35. http://dx.doi.org/10.1093/clinchem/31.12.1931.
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Abstract In situ monitoring has been increasingly accepted during the past five years. This approach has been applied to measurement of gas tensions such as pO2 and pCO2, to pH and ions, to the assessment of jaundice by measurement of bilirubin, and to analysis for 14CO2 after administration of labeled antipyrine and aminopyrine, for evaluation of hepatic damage. Various techniques have been developed for in situ monitoring: transcutaneous measurements, implantable sensors, ingestible radio-sensitive pills, and breath analysis. Here I review some of these approaches and their limitations. These limitations include the sparsity of circumstances under which the technique can be applied and the probable increase in health-care costs.
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Niranjana, Ms E. « Cough Monitoring with Cardiopulmonary Measurements ». International Journal for Research in Applied Science and Engineering Technology 8, no 5 (31 mai 2020) : 117–21. http://dx.doi.org/10.22214/ijraset.2020.5020.
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Brettle, Mike. « Future measurements for climate monitoring ». Weather 70, no 10 (octobre 2015) : 301–2. http://dx.doi.org/10.1002/wea.2524.
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Abbasi, Saddam Akber. « Monitoring Analytical Measurements in Presence of Two Component Measurement Error ». Журнал аналитической химии 69, no 11 (2014) : 1123–29. http://dx.doi.org/10.7868/s0044450214110127.
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Abbasi, Saddam Akber. « Monitoring analytical measurements in presence of two component measurement error ». Journal of Analytical Chemistry 69, no 11 (21 octobre 2014) : 1023–29. http://dx.doi.org/10.1134/s1061934814110100.
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Fišák, J., J. Chum, J. Vojta et K. Bartůňková. « Automatic Monitoring of the Amount of Deposited Precipitation ». Journal of Hydrometeorology 14, no 2 (1 avril 2013) : 670–76. http://dx.doi.org/10.1175/jhm-d-12-073.1.
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Abstract An automatic device for measurement of the amount (weight) of deposited precipitation developed at the Institute of Atmospheric Physics, Academy of Sciences of the Czech Republic, is described. Examples of measurements of various types of deposited precipitation are presented. The paper also discusses the response of the measuring instrument to falling precipitation and the influence of wind on the measurements. The results of first measurements proved that the instrument is suitable for automatic and continuous monitoring of deposited precipitation.
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Michel, Chris, et Sina Keller. « Advancing Ground-Based Radar Processing for Bridge Infrastructure Monitoring ». Sensors 21, no 6 (20 mars 2021) : 2172. http://dx.doi.org/10.3390/s21062172.
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In this study, we further develop the processing of ground-based interferometric radar measurements for the application of bridge monitoring. Applying ground-based radar in such complex setups or long measurement durations requires advanced processing steps to receive accurate measurements. These steps involve removing external influences from the measurement and evaluating the measurement uncertainty during processing. External influences include disturbances caused by objects moving through the signal, static clutter from additional scatterers, and changes in atmospheric properties. After removing these influences, the line-of-sight displacement vectors, measured by multiple ground-based radars, are decomposed into three-dimensional displacement components. The advanced processing steps are applied exemplarily on measurements with two sensors at a prestressed concrete bridge near Coburg (Germany). The external influences are successfully removed, and two components of the three-dimensional displacement vector are determined. A measurement uncertainty of less than 0.1 mm is achieved for the discussed application.
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Sysyn, Mykola, Olga Nabochenko, Ulf Gerber, Vitalii Kovalchuk et Oleksiy Petrenko. « COMMON CROSSING CONDITION MONITORING WITH ON BOARD INERTIAL MEASUREMENTS ». Acta Polytechnica 59, no 4 (31 août 2019) : 423–34. http://dx.doi.org/10.14311/ap.2019.59.0423.
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A railway turnout is an element of the railway infrastructure that influences the reliability of a railway traffic operation the most. The growing necessity for the reliability and availability in the railway transportation promotes a wide use of condition monitoring systems. These systems are typically based on the measurement of the dynamic response during operation. The inertial dynamic response measurement with on-board systems is the simplest and reliable way of monitoring the railway infrastructure. However, the new possibilities of condition monitoring are faced with new challenges of the measured information utilization. The paper deals with the condition monitoring of the most critical part of turnouts - the common crossing. The application of an on-board inertial measurement system ESAH-F for a crossing condition monitoring is presented and explained. The inertial measurements are characterized with the low correlation of maximal vertical accelerations to the lifetime. The data mining approach is used to recover the latent relations in the measurement’s information. An additional time domain and spectral feature sets are extracted from axle-box acceleration signals. The popular spectral kurtosis features are used additionally to the wavelet ones. The feature monotonicity ranking is carried out to select the most suited features for the condition indicator. The most significant features are fused in a one condition indicator with a principal component analysis. The proposed condition indicator delivers an almost two-time higher correlation to the lifetime as the maximal vertical accelerations. The regression analysis of the indicator to the lifetime with an exponential fit proves its good applicability for the crossing residual useful life prognosis.
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Skrzypczak, Izabela, Janusz Kogut, Wanda Kokoszka et Dawid Zientek. « Monitoring of Landslide Areas with the Use of Contemporary Methods of Measuring and Mapping ». Civil And Environmental Engineering Reports 24, no 1 (28 mars 2017) : 69–82. http://dx.doi.org/10.1515/ceer-2017-0005.
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Abstract In recent years, there is an increase of landslide risk observed, which is associated with intensive anthropogenic activities and extreme weather conditions. Appropriate monitoring and proper development of measurements resulting as maps of areas at risk of landslides enables us to estimate the risk in the social and economic aspect. Landslide monitoring in the framework of SOPO project is performed by several methods of measurements: monitoring of surface (GNSS measurement and laser scanning), monitoring in-deepth (inclinometer measurements) and monitoring of the hydrological changes and precipitation (measuring changes in water-table and rainfall).
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Setiawan, Foni Agus, et Yuli Sudriani. « System Engineering for Online Monitoring and Early Warning of Water Environment ». Jurnal INKOM 9, no 2 (30 mai 2016) : 49. http://dx.doi.org/10.14203/j.inkom.422.
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Measurement activity usually performed at a time or in a certain time period. In the case of measurements at one time, measurements manually by visiting the location of measurements, take measurements and write them down, then left the location is not a problem. However, measurements made within a certain period of time or year would be verydraining, costly, and time consuming if perfomed manually. Thus, design and implementation of embedded system for online monitoring and early warning of water environment is proposed. The system consists of two parts i.e. monitoring stations (site) and monitoring center (server). A monitoring station is an embedded system that has interface with a logger. Monitoring center is a computer that runs the service that gets the data sent by the monitoring stations, process it and put it into the database. Monitoring center also runan http service to display data acquired from monitoring stations to end users both in tabular or graphical view . The system can perform continuous measurements and its results can be monitored remotely.
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Altundas, Yusuf Bilgin, et Nikita Chugunov. « Multiphysics fluid monitoring : Toward targeted monitoring design under uncertainty ». Interpretation 6, no 3 (1 août 2018) : SG19—SG32. http://dx.doi.org/10.1190/int-2017-0180.1.
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Properly designed multiphysics measurements program can improve the accuracy of fluid front monitoring (FFM) by combining tools with various spatial resolutions and desired contrast in time-lapse measurements, consequently enabling better sweep efficiency and increased oil recovery. We have introduced a new workflow for multiphysics FFM feasibility studies that determines the suitability of measurements considered for monitoring and enables informed decision making on where, when, and how often the measurements need to be performed. The workflow integrates petrophysically and thermodynamically consistent multiphysics responses for seismic, electromagnetic, and neutron capture measurements. We argue that, in the presence of multiple sources of uncertainty, reservoir performance should be analyzed from a 4D probabilistic standpoint, rather than just by looking at a traditional spread in cumulative production curves. Consequently, the monitoring program should be designed around our understanding of reservoir 4D probabilistic performance through consistent multiphysics modeling. We have developed a set of approaches to enable addressing both tasks on a single platform with all relevant sources of uncertainties including parametric and model uncertainties in effective medium modeling and reservoir simulation. The developed workflow is illustrated using the ISAPP Field Development Optimization Challenge benchmark data set introduced in 2017.
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Oakley, RE, B. Olivier, GE Eyster et JG Hauptman. « Experimental evaluation of central venous pressure monitoring in the dog ». Journal of the American Animal Hospital Association 33, no 1 (1 janvier 1997) : 77–82. http://dx.doi.org/10.5326/15473317-33-1-77.
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The measurement of central venous pressure (CVP) will provide objective information about intravascular blood volume. Limitations exist with direct and indirect methods of measuring CVP; however, the purpose of this study was to determine if such factors as catheter size, patient position, or measurements taken with either a water manometer or a strain-gauge transducer would affect the accuracy of CVP measurements. The study population consisted of six adult, mixed-breed dogs. Catheter sizes evaluated were 16- and 19-gauge. Patient positions evaluated were right and left lateral recumbencies. Right atrial pressures (RAPs) were used as the reference standards for CVP measurements. Measurements of RAP and CVP were obtained with a water manometer and a strain-gauge transducer. No significant differences were observed in measured CVPs for the effects of catheter size and right versus left lateral recumbency. A 2.7-mmHg difference in water manometry was demonstrated when compared to strain-gauge transducer measurements. Also, strain-gauge transducer measurements had less precision compared to water manometer measurements.
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Wei, Yukun, Anders B. Lundberg et Fredrik Resare. « Systematic slope stability assessment through deformation field monitoring ». E3S Web of Conferences 92 (2019) : 18009. http://dx.doi.org/10.1051/e3sconf/20199218009.
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Field monitoring is frequently carried out during excavations and other geotechnical activities and provides additional information during the execution of a construction project. The interpretation of field monitoring data is often obscured by measurement noise and disturbance, and a systematic approach to assess both the quality and implications of the field monitoring data is very helpful in geotechnical practice. The possibility to infer practical conclusions from the field monitoring data depends on the type of field measurements, especially in monitoring of the stability of slopes. Pore pressure measurements can serve as a direct measurement of utilized soil strength for a slope, while deformation measurements are significantly more ambiguous and complicates the interpretation. The assessment of slope stability through field monitoring of deformations requires inverse or back analysis of the soil properties, followed by a forward analysis of the resulting slope stability. Such an inverse or back analysis is frequently influenced by non-uniqueness of the material properties and the stability of the measurement data. Systematic approaches to inverse or back analysis have been demonstrated in the scientific literature, but the practical use of these methods is not entirely straight-forward. The current paper presents a case study of systematic slope stability assessment through field measurements of deformations with a review of the field monitoring programme, numerical simulations of deformations, and a simplified approach to back analysis of the soil parameters. The excavation of a slope in an urban environment including layers of organic clay covered with highly heterogeneous gravel fill is used as an example of geotechnical back analysis. The aim is to elucidate some of the challenges in geotechnical back analysis while providing some practical solutions for practice.
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Majcherczyk, Tadeusz, Zbigniew Niedbalski et Artur Ulaszek. « Roadway Stability Evaluation on the Basis of Modern Monitoring of Displacement ». Studia Geotechnica et Mechanica 37, no 1 (1 mars 2015) : 45–52. http://dx.doi.org/10.1515/sgem-2015-0006.
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Abstract The paper presents the application of a 3D laser measurement technology in a modern monitoring of roadways. The authors analyze the possibility of using a three-dimensional scanning measurement of longwall working dimensions. The measurement results are presented in the form of a cloud of points obtained from a 3D laser scanning. The paper also presents a comparison of the results obtained from the convergence of traditionally-made measurements with the measurements derived from the threedimensional scanning and discusses possible methods of comparing different point clouds.
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Malinowski, Pawel, Tomasz Wandowski et Wieslaw Ostachowicz. « Guided Waves for Aircraft Panel Monitoring ». Key Engineering Materials 558 (juin 2013) : 107–15. http://dx.doi.org/10.4028/www.scientific.net/kem.558.107.
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The reported research concerns experimental investigation toward the monitoring of an aircraft panel. Guided wave propagation phenomena were used to obtain information about the state of the monitored structure. A curved aluminium panel with rivets was investigated. Piezoelectric transducer was used to excite guided waves in chosen structural element. The generated signal was amplified before applying it to the transducer in order to ensure measurable amplitude of excited guided waves. Measurement of the wave field was realized using laser scanning vibrometer that registered the velocity responses at a points belonging to a defined mesh. This contactless measurement technique allowed to investigate phenomena related to wave propagation in the aircraft panel. In the first stage, due to high complexity of the element, baseline measurements were taken. Next, a discontinuity (additional mass) was introduced on the panel surface and the measurements were repeated. Signal processing methods for features extraction from signals were proposed. These features were applied in order to detect and localize the presence anomalies in the investigated panel. The signal processing was conducted in MATLAB with the procedures developed by the authors. The used measurement technology (vibrometer) allowed to register whole wavefield of the propagating guided waves. This allowed to visualize the interaction of the waves with rivets. After introducing the discontinuity on the panel surface wave interaction with it was investigated. Two positions of the additional mass were considered. One just before the riveted stiffener and second after the stiffener. Because of this the influence of the stiffener on the damage detection abilities could be investigated. It can be concluded that the guided wave can be used for monitoring of such complex structures. The vibrometer measurements allowed learn about the guided wave propagation phenomena and perform successful damage localization.
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Piccolo, Arianna, Yann Lecieux, Sylvie Lesoille, Pierre Teixeira, Johan Bertrand et Dominique Leduc. « Performance Assessment of Distributed Strain Sensing Techniques for Convergence Monitoring of Radioactive Waste Repository ». Sensors 23, no 1 (30 décembre 2022) : 398. http://dx.doi.org/10.3390/s23010398.
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This paper presents the measurement methodology of diameter reduction monitoring of micro-tunnel structures used for radioactive waste storage based on distributed strain measurements along fiber optic sensors installed on the circumference. The whole measurement procedure is described: the calibration of the sensors for use in harsh environment (temperature and radioactivity), the measurement analysis technique, the performance assessment of different measurement systems on a surface mock-up and the in-situ validation on an underground structure. The performances of Brillouin and Rayleigh backscattering measurements are compared, as well as different fixation technologies. Distributed measurements are compared to alternative measurements: displacement sensors, Bragg grating extensometers and MEMS accelerometers. The distributed Rayleigh backscattering measurement performed on optical cables bonded to the surface of the structure appears to be the best solution for monitoring the convergence of micro-tunnels and offers comparable performance to alternative technologies tested on the surface demonstrator.
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Lamy, Kévin, Marion Ranaivombola, Hassan Bencherif, Thierry Portafaix, Mohamed Toihir, Kaisa Lakkala, Antti Arola, Jukka Kujanpää, Mikko Pitkänen et Jean-Maurice Cadet. « Monitoring Solar Radiation UV Exposure in the Comoros ». International Journal of Environmental Research and Public Health 18, no 19 (5 octobre 2021) : 10475. http://dx.doi.org/10.3390/ijerph181910475.
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As part of the UV-Indien project, a station for measuring ultraviolet radiation and the cloud fraction was installed in December 2019 in Moroni, the capital of the Comoros, situated on the west coast of the island of Ngazidja. A ground measurement campaign was also carried out on 12 January 2020 during the ascent of Mount Karthala, located in the center of the island of Ngazidja. In addition, satellite estimates (Ozone Monitoring Instrument and TROPOspheric Monitoring Instrument) and model outputs (Copernicus Atmospheric Monitoring Service and Tropospheric Ultraviolet Model) were combined for this same region. On the one hand, these different measurements and estimates make it possible to quantify, evaluate, and monitor the health risk linked to exposure to ultraviolet radiation in this region, and, on the other, they help to understand how cloud cover influences the variability of UV-radiation on the ground. The measurements of the Ozone Monitoring Instrument onboard the EOS-AURA satellite, being the longest timeseries of ultraviolet measurements available in this region, make it possible to quantify the meteorological conditions in Moroni and to show that more than 80% of the ultraviolet indices are classified as high and that 60% of these are classified as extreme. The cloud cover measured in Moroni by an All Sky Camera was used to distinguish between the cases of UV index measurements taken under clear or cloudy sky conditions. The ground-based measurements thus made it possible to describe the variability of the diurnal cycle of the UV index and the influence of cloud cover on this parameter. They also permitted the satellite measurements and the results of the simulations to be validated. In clear sky conditions, a relative difference of between 6 and 11% was obtained between satellite or model estimates and ground measurements. The ultraviolet index measurement campaign on Mount Karthala showed maximum one-minute standard erythemal doses at 0.3 SED and very high daily cumulative erythemal doses at more than 80 SED. These very high levels are also observed throughout the year and all skin phototypes can exceed the daily erythemal dose threshold at more than 20 SED.
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Goodrich, James T. « Electrophysiologic Measurements : Intraoperative Evoked Potential Monitoring ». Anesthesiology Clinics of North America 5, no 3 (septembre 1987) : 477–89. http://dx.doi.org/10.1016/s0889-8537(21)00328-x.
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MISHIMA, Ken. « Dielectric Measurements for Monitoring Cell Concentrations ». JOURNAL OF THE BREWING SOCIETY OF JAPAN 88, no 9 (1993) : 660–64. http://dx.doi.org/10.6013/jbrewsocjapan1988.88.660.
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Leslie, D. M., et B. M. Hartley. « Reservoir Monitoring with Continuous Acoustic Measurements ». ASEG Extended Abstracts 2003, no 2 (août 2003) : 1. http://dx.doi.org/10.1071/aseg2003ab097.
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Rodriguez-Alvarez, Nereida, Albert Aguasca, Enric Valencia, Xavier Bosch-Lluis, Adriano Camps, Isaac Ramos-Perez, Hyuk Park et Merce Vall-llossera. « Snow Thickness Monitoring Using GNSS Measurements ». IEEE Geoscience and Remote Sensing Letters 9, no 6 (novembre 2012) : 1109–13. http://dx.doi.org/10.1109/lgrs.2012.2190379.
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Vinogradov, E. A., E. M. Gorbunova, N. V. Kabychenko, G. G. Kocharyan, D. V. Pavlov et I. S. Svintsov. « Groundwater level monitoring by precision measurements ». Water Resources 39, no 7 (décembre 2012) : 802–10. http://dx.doi.org/10.1134/s0097807812070135.
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Scruby, C. B., M. J. Beesley, K. A. Stacey et D. J. Buttle. « Continuous monitoring by acoustic emission measurements ». NDT & ; E International 25, no 6 (décembre 1992) : 297. http://dx.doi.org/10.1016/0963-8695(92)90710-x.
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Bury, M., J. Gerhards et W. Erni. « Monitoring sedimentation processes by conductivity measurements ». International Journal of Pharmaceutics 76, no 3 (octobre 1991) : 207–16. http://dx.doi.org/10.1016/0378-5173(91)90273-q.
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Vargas, M., A. Guisasola, J. Lafuente, C. Casas et J. A. Baeza. « On-line titrimetric monitoring of anaerobic–anoxic EBPR processes ». Water Science and Technology 57, no 8 (1 avril 2008) : 1149–54. http://dx.doi.org/10.2166/wst.2008.140.
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Denitrifying phosphorus accumulating organisms (DPAO) are able to remove nitrogen and phosphorus simultaneously. The use of DPAO in EBPR systems results in a substantial saving on aeration cost and a lower sludge production when compared to anaerobic–aerobic EBPR systems. This process is usually studied in sequencing batch reactors (SBR) and monitored with off-line measurements. However, off-line monitoring implies low frequency data sampling and delay between sampling and obtainment of the results. For this reason, an online measurement such as titrimetry is strongly recommended to improve the daily management of the lab-scale SBR. This paper shows different applications of titrimetric measurements for on-line monitoring of DPAO lab-scale SBR cycles. The results demonstrate that titrimetry is a suitable tool for detecting the end of phosphorus release and carbon substrate depletion point in the anaerobic phase. Moreover, this paper proposes the indirect measurement of nitrate/nitrite uptake rate with titrimetric measurements, which allows the on-line estimation of its concentration during the anoxic phase. Therefore, titrimetry is an on-line measurement with a high potential to implement new control strategies in DPAO lab-scale SBR systems.
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Moore, C., A. Barnard, P. Fietzek, M. R. Lewis, H. M. Sosik, S. White et O. Zielinski. « Optical tools for ocean monitoring and research ». Ocean Science 5, no 4 (10 décembre 2009) : 661–84. http://dx.doi.org/10.5194/os-5-661-2009.
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Abstract. Requirements for understanding the relationships between ocean color and suspended and dissolved materials within the water column, and a rapidly emerging photonics and materials technology base for performing optical based analytical techniques have generated a diverse offering of commercial sensors and research prototypes that perform optical measurements in water. Through inversion, these tools are now being used to determine a diverse set of related biogeochemical and physical parameters. Techniques engaged include measurement of the solar radiance distribution, absorption, scattering, stimulated fluorescence, flow cytometry, and various spectroscopy methods. Selective membranes and other techniques for material isolation further enhance specificity, leading to sensors for measurement of dissolved oxygen, methane, carbon dioxide, common nutrients and a variety of other parameters. Scientists are using these measurements to infer information related to an increasing set of parameters and wide range of applications over relevant scales in space and time.
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Moore, C., A. Barnard, P. Fietzek, M. R. Lewis, H. M. Sosik, S. White et O. Zielinski. « Optical tools for ocean monitoring and research ». Ocean Science Discussions 5, no 4 (27 novembre 2008) : 659–717. http://dx.doi.org/10.5194/osd-5-659-2008.
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Abstract. Requirements for understanding the relationships between ocean color and suspended and dissolved materials within the water column, and a rapidly emerging photonics and materials technology base for performing optical based analytical techniques have generated a diverse offering of commercial sensors and research prototypes that perform optical measurements in water. Through inversion, these tools are now being used to determine a diverse set of related biogeochemical and physical parameters. Techniques engaged include measurement of the solar radiance distribution, absorption, scattering, stimulated fluorescence, flow cytometry, and various spectroscopy methods. Selective membranes and other techniques for material isolation further enhance specificity, leading to sensors for measurement of dissolved oxygen, methane, carbon dioxide, common nutrients and a variety of other parameters. Scientists are using these measurements to infer information related to an increasing set of parameters and wide range of applications over relevant scales in space and time.
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Holt, David W. « Monitoring mycophenolic acid ». Annals of Clinical Biochemistry : International Journal of Laboratory Medicine 39, no 3 (1 mai 2002) : 173–83. http://dx.doi.org/10.1258/0004563021902035.
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The immunosuppressive agent mycophenolate mofetil is a prodrug for the active compound mycophenolic acid. Following organ transplantation, it is used mostly in combination with other immunosuppressive drugs, but it has also been used as primary therapy. Although in the pivotal clinical studies the drug was given in fixed doses, there has been substantial interest in the measurement of mycophenolic acid in plasma as a guide to optimizing therapy. Data have emerged which indicate that the metabolism of the compound is more complex than was originally thought and that variability in exposure to the drug, assessed by area under the time-concentration curve, is an important determinant of efficacy. This article highlights basic pharmacokinetic and pharmacodynamic data for mycophenolic acid, which underlie the rationale for its measurement. These data are then set in the context of providing a routine service for the measurement of the drug with either of the analytical techniques currently available - immunoassay or high performance liquid chromatography. There are a number of issues regarding the clinical interpretation of mycophenolic acid measurements which are yet to be resolved. Centres contemplating the introduction of such a service will need to keep abreast of a rapidly evolving literature.
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Coker, S. A., S. J. Oh et Y. C. Shin. « In-Process Monitoring of Surface Roughness Utilizing Ultrasound ». Journal of Manufacturing Science and Engineering 120, no 1 (1 février 1998) : 197–200. http://dx.doi.org/10.1115/1.2830101.
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This paper presents the capability of an ultrasonic system for the in-process surface roughness measurement of machined parts. The system uses a focused ultrasonic transducer to measure the reflected amplitude variation of an ultrasonic beam incident on the surface. The robustness of the system is examined by applying the technique to different machined surfaces and investigating the effect of various coupling fluids. Experimental results show that the technique is applicable to the surfaces produced by most production processes. In addition, the capability of in-process measurements is demonstrated by adapting the system to a CNC machining center. Results show in-process measurements correlate well with off-line profilometer data. Tolerance to machine vibration is also shown by comparing the measurement data with the machine spindle on and off.
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Nixdorf, Erik, Daniel Eggert, Peter Morstein, Thomas Kalbacher et Doris Dransch. « Tocap : a web tool for ad-hoc campaign planning in terrestrial hydrology ». Journal of Hydroinformatics 24, no 2 (21 janvier 2022) : 274–94. http://dx.doi.org/10.2166/hydro.2022.057.
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Abstract Planning an event-based monitoring campaign on the regional scale is challenging, e.g. the timing and location of monitoring visits can dramatically impact monitoring efficacy and depends on the optimal environmental conditions required by the measurement parameters and the overarching monitoring goal. Therefore we developed a generic campaign planning approach utilizing interactive visualization methods and implemented this approach into the component-based web tool called Tocap: Tool for Campaign Planning. As a case study, we determine the most suitable time and location for event-driven, ad-hoc monitoring in hydrology using soil moisture measurements as our target variable. Our approach supports: (1) data acquisition from various digital data sources, (2) identification of the most suitable locations for measurements, (3) identification of the most suitable time for measurements at the selected locations, and (4) planning an optimized monitoring route.
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Pasternak, Grzegorz, Janina Zaczek-Peplinska, Klaudia Pasternak, Jacek Jóźwiak, Mariusz Pasik, Eugeniusz Koda et Magdalena Daria Vaverková. « Surface Monitoring of an MSW Landfill Based on Linear and Angular Measurements, TLS, and LIDAR UAV ». Sensors 23, no 4 (7 février 2023) : 1847. http://dx.doi.org/10.3390/s23041847.
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Surface monitoring of landfills is crucial not only during their operation but also for later land restoration and development. Measurements concern environmental factors, such as leachate, migration of pollutants to water, biogas, and atmospheric emissions, and geotechnical factors, such as stability and subsidence. Landfill subsidence can be measured using modern surveying techniques. Modern measurement methods for landfill body displacement monitoring and their control after restoration and adaptation as recreational areas include terrestrial laser scanning (TLS), and scanning and low-altitude photogrammetric measurements from an unmanned aerial vehicle (UAV). The acquired measurement data in the form of 3D point clouds should be referenced to the local control network to enable a comprehensive analysis of data acquired using various techniques, including geotechnical sensors such as benchmarks, piezometers, and inclinometers. This study discusses the need for surface monitoring of municipal solid waste (MSW) landfills. A properly 3-D mapped landfill mass is the basis for ensuring the geotechnical safety of the restored landfill. Based on archival data and current measurements of the Radiowo landfill (Poland), this study compares the advantages and limitations of the following measurement techniques: linear and angular measurements, satellite measurements, TLS, and UAV scanning and photogrammetry, considering specific conditions of the location and vegetation of the landfill. Solutions for long-term monitoring were proposed, considering the cost and time resolution necessary for creating a differential model of landfill geometry changes.
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Strömbergsson, D., P. Marklund, K. Berglund et P.-E. Larsson. « Property requirements of vibration measurements in wind turbine drivetrain bearing condition monitoring ». Insight - Non-Destructive Testing and Condition Monitoring 63, no 11 (1 novembre 2021) : 667–74. http://dx.doi.org/10.1784/insi.2021.63.11.667.
Texte intégralRésumé :
Wind turbine drivetrain bearing failures continue to lead to high costs resulting from turbine downtime and maintenance. As the standardised tool to best avoid downtime is online vibration condition monitoring, a lot of research into improving the signal analysis tools of the vibration measurements is currently being performed. However, failures in the main bearing and planetary gears are still going undetected in large numbers. The available field data is limited when it comes to the properties of the stored measurements. Generally, the measurement time and the covered frequency range of the stored measurements are limited compared to the data used in real-time monitoring. Therefore, it is not possible to either reproduce the monitoring or to evaluate new tools developed through research for signal analysis and diagnosis using the readily available field data. This study utilises 12 bearing failures from wind turbine condition monitoring systems to evaluate and make recommendations concerning the optimal properties in terms of measurement time and frequency range the stored measurements should have. The results show that the regularly stored vibration measurements that are available today are, throughout most of the drivetrain, not optimal for research-driven postfailure investigations. Therefore, the storage of longer measurements covering a wider frequency range needs to begin, while researchers need to demand this kind of data.
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Hertel, Ole, Thomas Ellermann, Finn Palmgren, Ruwim Berkowicz, Per Løfstrøm, Lise Marie Frohn, Camilla Geels et al. « Integrated air-quality monitoring - combined use of measurements and models in monitoring programmes ». Environmental Chemistry 4, no 2 (2007) : 65. http://dx.doi.org/10.1071/en06077.
Texte intégralRésumé :
Environmental context. Optimisation of allocated resources, improved quality, and better understanding of processes – these are the main advantages of applying integrated monitoring (IM). The paper describes IM as a combination of air pollution measuring and modelling, and describes how it is implemented in air-quality management in Denmark. However, the IM concept may also be applied to follow air-quality levels in other countries that currently do not have a corresponding system. It may also be applied to the environmental monitoring of other compartments. Abstract. Integrated air-quality monitoring (IM) is here defined as monitoring based on the combination of results of atmospheric measurements from usually fixed site stations, and results obtained from calculations with air-quality models. This paper outlines experience from the use of IM at the National Environmental Research Institute (NERI) within the two nationwide air-quality monitoring programmes for the Danish urban and rural environments, respectively. The measurements in these Danish monitoring programmes are used to determine actual levels and trends in pollutant concentrations and depositions of pollutants. The measurements are further used for process understanding, and for the development and validation of air-quality models. The results from the air-quality models are used in the interpretation of measurements, but they are also used to provide information about, for example, source apportionment. The model calculations are used to extend the geographical coverage of the monitoring, and to provide information about pollution loads at locations or regions that are not well covered by the limited number of measurement stations in the monitoring programmes. Finally, the air-quality models are applied to carry out scenario studies of future pollution loads, e.g. assessment of the effects of various emission reduction strategies. NERI operates and holds the overall responsibility for the Danish air-quality monitoring programmes. These monitoring programmes are designed to fulfil the Danish obligations in relation to the EU directives on air quality, as well as the Danish obligations in relation to the reporting of data to international organisations (EMEP, HELCOM, OSPARCOM, and WHO). The obtained results from the use of IM form the basis for the national assessment of the air pollution loads in relation to protection of the aquatic and terrestrial environment; in these assessments the use of IM plays a central role.
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Krause, Stuart, Tanja G. M. Sanders, Jan-Peter Mund et Klaus Greve. « UAV-Based Photogrammetric Tree Height Measurement for Intensive Forest Monitoring ». Remote Sensing 11, no 7 (28 mars 2019) : 758. http://dx.doi.org/10.3390/rs11070758.
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The measurement of tree height has long been an important tree attribute for the purpose of calculating tree growth, volume, and biomass, which in turn deliver important ecological and economical information to decision makers. Tree height has traditionally been measured by indirect field-based techniques, however these methods are rarely contested. With recent advances in Unmanned Aerial Vehicle (UAV) remote sensing technologies, the possibility to acquire accurate tree heights semi-automatically has become a reality. In this study, photogrammetric and field-based tree height measurements of a Scots Pine stand were validated using destructive methods. The intensive forest monitoring site implemented for the study was configured with permanent ground control points (GCPs) measured with a Total Station (TS). Field-based tree height measurements resulted in a similar level of error to that of the photogrammetric measurements, with root mean square error (RMSE) values of 0.304 m (1.82%) and 0.34 m (2.07%), respectively (n = 34). A conflicting bias was, however, discovered where field measurements tended to overestimate tree heights and photogrammetric measurements were underestimated. The photogrammetric tree height measurements of all trees (n = 285) were validated against the field-based measurements and resulted in a RMSE of 0.479 m (2.78%). Additionally, two separate photogrammetric tree height datasets were compared (n = 251), and a very low amount of error was observed with a RMSE of 0.138 m (0.79%), suggesting a high potential for repeatability. This study shows that UAV photogrammetric tree height measurements are a viable option for intensive forest monitoring plots and that the possibility to acquire within-season tree growth measurements merits further study. Additionally, it was shown that negative and positive biases evident in field-based and UAV-based photogrammetric tree height measurements could potentially lead to misinterpretation of results when field-based measurements are used as validation.
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Groenenboom, Jeroen, et Dirkjan B. van Dam. « Monitoring hydraulic fracture growth : Laboratory experiments ». GEOPHYSICS 65, no 2 (mars 2000) : 603–11. http://dx.doi.org/10.1190/1.1444756.
Texte intégralRésumé :
We carry out small‐scale hydraulic fracture experiments to investigate the physics of hydraulic fracturing. The laboratory experiments are combined with time‐lapse ultrasonic measurements with active sources using both compressional and shear‐wave transducers. For the time‐lapse measurements we focus on ultrasonic measurement changes during fracture growth. As a consequence we can detect the hydraulic fracture and characterize its shape and geometry during growth. Hence, this paper deals with fracture characterization using time‐lapse acoustic data. During fracture growth the acoustic waves generate diffractions at the tip of the fracture. The direct compressional and shear diffractions are used to locate the position of the tip of the fracture. More detailed analysis of these diffractions can be used to obtain information on the geometry and configuration of the fracture tip, including the creation of a zone that is not penetrated by fluid. Furthermore, it appears that the acoustic diffraction is generated mainly at the fluid front and only weakly at the dry tip. In addition, the wavefield that has been transmitted through the hydraulic fracture is measured. Shear‐wave transmissions are shadowed because the shear modulus vanishes inside the fluid‐filled fracture. From this observation we conclude that the fracture is mechanically open. In other words, no friction occurs related to the movement of fracture faces that are in mechanical contact. Compressional transmissions show a distinctive dispersion relative to the measurement in the unfractured medium. This dispersion can be used to determine the width (or aperture) of the fracture by fitting the measured dispersion with the theoretical prediction as a function of the unknown fracture width. We show that the width profile of the fracture can be reconstructed by using a set of transmission records with different source and receiver locations. By performing a validation experiment, we show that the width determination method is reliable, although the estimated fracture width is only a few percent of the incident wavelength. The strength of the method relies on time‐lapse measurements combined with fitting the changes in the measured waveforms during the experiment. The combination of diffractions and transmissions helps us visualize the dynamic process of hydraulic fracture growth. Hence, acoustic measurements with active sources prove their usefulness for fracture characterization.
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Zhang, Xingfu, Yongyi Zhang, Lei Zhang, Guangxin Qiu et Dehong Wei. « Power Transmission Tower Monitoring with Hydrostatic Leveling System : Measurement Refinement and Performance Evaluation ». Journal of Sensors 2018 (30 décembre 2018) : 1–12. http://dx.doi.org/10.1155/2018/4176314.
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A hydrostatic leveling system (HLS) is an automated high-accuracy measurement technology widely used for vertical displacement monitoring. This paper focuses on evaluating the performance of HLS for monitoring the deformation of a power transmission tower base together with a slope sensor and displacement meter. The monitoring results show that HLS measurements are strongly affected by the environmental temperature. Therefore, to obtain the actual deformation of a monitoring target, the measurements should be further processed to reduce the effect of temperature on the result. To this end, four data processing schemes are proposed, which are based on the frequency of processing (i.e., day by day, monthly, quarterly, or annually). The results demonstrate that the quarterly processing scheme effectively reduces the impact of temperature on deformation measurements and therefore provides the most accurate results among the four schemes considered. Since after correction, the HLS measurements are consistent with the independent monitoring results obtained from the slope sensor and displacement meter, the proposed correction strategy is workable and might be considered for similar monitoring scenarios in future.
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Lüley, Jakub, Branislav Vrban, Štefan Čerba, Filip Osuský et Vladimír Nečas. « Unmanned Radiation Monitoring System ». EPJ Web of Conferences 225 (2020) : 08008. http://dx.doi.org/10.1051/epjconf/202022508008.
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The absence of online radiation monitoring systems has been observed in the case of Fukushima nuclear accident. As the tsunami destroyed 23 of the 24 status monitoring points, almost no relevant radiation dose measurements data were available. A rapid deployment of a mobile radiological unit that can quickly determine the activity and direction of the radioactive cloud spread on the ground or in the air can prevent unnecessary deaths and related financial losses. Although the design of the current generation of NPPs incorporates features that minimize the risk of large radioactive releases outside the reactor, it is still important to focus on the development of systems that can mitigate the consequences of such events. In situations when the level of radiation does not permit the personal to perform the required measurements, online unmanned radiation monitoring systems may come to the play. For such a purpose the RMS-00x radiation monitoring system could be used, which is a modular system covering the functionality of dose rate measurement, air sampling and radiation map creation without requiring the human personnel to be present at the measurement site. The main purpose of the RMS-00x radiation monitoring system is the rapid deployment of unmanned monitoring devices to reduce the radiation burden on workers and on public. The system can be applied in the vicinity of a nuclear power plant (NPP) or at any location, where source of ionizing radiation could be present. Before this system is used in real conditions, its components must be thoroughly calibrated, based on certified measurement equipment and state-of-art simulation tools. This paper deals with the description of the RMS-00X sensor modules and demonstrates their functionality in combination with UAV. In addition, demonstration of the use of the developed technology was carried out as part of the regular emergency planning and preparedness of EBO NPP on 26th October 2017.
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RECIOUI, Abdelmadjid, Mohamed TAZIBT et Hakim BENHENNI. « Fault Detection in Wide Area Monitoring Systems via PMU Optimal Placement ». Algerian Journal of Signals and Systems 2, no 3 (15 septembre 2017) : 149–61. http://dx.doi.org/10.51485/ajss.v2i3.41.
Texte intégralRésumé :
The Phasor measurement units (PMUs) have become more and more attractive in power engineering as they can provide synchronized measurements of real-time voltage and currents phasors. The objective of this work is twofold: first, the optimal placement of PMUs is done in the standardized IEEE systems. Next, fault location is determined based on the measurements collected from these PMUs. The simulations are carried out using MATLAB SIMULINK. The results show that it is possible to exploit the PMU measurement data to locate and hence cure the faults in the power system.
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Vašátko, Radek, et Jan L. Vítek. « Long-Term Monitoring of Concrete Building Structure ». Solid State Phenomena 272 (février 2018) : 160–65. http://dx.doi.org/10.4028/www.scientific.net/ssp.272.160.
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Long-term deformations of the concrete are important for determination of behavior of concrete structures. For prediction of the long-term deformations rheological models are used. The models are usually derived from measurements on laboratory specimens. There are only few measurements performed on real structures. The objective of the realized experimental program is to compare predicted values of strains and strains measured on a real structure. Vibrating wire strain gauges have been installed in two columns in underground floors of eight-storey office building. Target of this paper is evaluation of measurement from the initial period (7 to 8 months). Measured values have been compared with results of first calculations and with values measured on laboratory specimens placed at the construction site.
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Radoi, Andrei, Cezar Margineanu, Constantin Ploesteanu et Vasile Pangratie. « Static and Dynamic Structural Health Monitoring System for Bridges ». Romanian Journal of Transport Infrastructure 10, no 1 (1 juillet 2021) : 108–23. http://dx.doi.org/10.2478/rjti-2021-0007.
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Abstract This document describes a system for static and dynamic monitoring of the structural health of bridges, but not only. The need to develop the system resulted from the difficulties encountered by the authors in installing and operating complex monitoring systems, composed of elements from different manufacturers, with different measurement technologies, power supplies, communication modes and software applications. The described system facilitates the integration of different measurements, sensors, power supplies and communication technologies, in a unitary system that allows both static and dynamic measurements, simultaneously.
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Klasnic, Ilija, Jasna Dragosavac et Zoran Lazarevic. « Improved hydrogenerator field winding thermal monitoring ». Thermal Science, no 00 (2023) : 36. http://dx.doi.org/10.2298/tsci221212036k.
Texte intégralRésumé :
A new monitoring method for determination of average hydrogenerator field winding temperature is introduced in order to increase the robustness of the temperature measurement system using the classic U-I method. The classic approach is prone to error due to brush voltage drop, especially when field voltage is low. Developed thermal model is based on field current and cold cooling air temperature measurements, as well on temperatures acquired from digital temperature sensors mounted across the field winding. To monitor the rotor temperature for generators with brushless excitation where field voltage and current measurements are not accessible, a mathematical model was developed to estimate the average field winding temperature based on the existing temperature monitoring of the cooling medium and mounted sensors. Importance of the proposed approach arises from the foreseen widespread use of brushless generators in distributed generation. The developed models were compared and their sensitivity was examined thoroughly.
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Orman, Maciej, et Cajetan Pinto. « Vibration, Sound and Thermal Analysis as a Condition Monitoring Methods for Electric Motors ». Applied Mechanics and Materials 239-240 (décembre 2012) : 462–67. http://dx.doi.org/10.4028/www.scientific.net/amm.239-240.462.
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This paper presents a comparison of different measurement techniques for condition monitoring of electric motors. Results are presented for vibration, acoustic and thermal analysis. Vibration signals were measured by piezoelectric accelerometers, acoustic by microphones and temperature data was collected by an infrared camera. Two induction motor cases were examined – healthy motor case and combination of static eccentricity with soft foot case. Vibration monitoring is a well known technique used in condition monitoring and in this work vibration measurements were used as a reference signal for assessment of the value of acoustic and thermal measurements. As presented in result section both acoustic analyses as well as thermal images appear as valuable techniques for condition monitoring of electric motors. All the measurements where conducted in an industrial environment.
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Weigand, Maximilian, Egon Zimmermann, Valentin Michels, Johan Alexander Huisman et Andreas Kemna. « Design and operation of a long-term monitoring system for spectral electrical impedance tomography (sEIT) ». Geoscientific Instrumentation, Methods and Data Systems 11, no 2 (30 novembre 2022) : 413–33. http://dx.doi.org/10.5194/gi-11-413-2022.
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Abstract. Spectral electrical impedance tomography (sEIT) is increasingly used to characterise the structure of subsurface systems using measurements in the megahertz to kilohertz range. Additionally, hydrogeophysical and biogeophysical processes are characterised and monitored using sEIT. The method combines multiple, spatially distributed, spectroscopic measurements with tomographic inversion algorithms to obtain images of the complex electrical resistivity distribution in the subsurface at various frequencies. Spectral polarisation measurements provide additional information about the systems under investigation and can be used to reduce ambiguities that occur if only the in-phase resistivity values are analysed. However, spectral impedance measurements are very sensitive to details of the measurement setup as well as to external noise and error components. Despite promising technical progress in improving measurement quality as well as progress in the characterisation and understanding of static polarisation signatures of the subsurface, long-term (i.e. multi-month to multi-year) monitoring attempts with fixed setups are still rare. Yet, measurement targets often show inherent non-stationarity that would require monitoring for a proper system characterisation. With the aim of improving operating foundations for similar endeavours, we here report on the design and field deployment of a permanently installed monitoring system for sEIT data. The specific aim of this monitoring installation is the characterisation of crop root evolution over a full growing season, requiring multiple measurements per day over multiple months to capture relevant system dynamics. In this contribution, we discuss the general layout and design of the monitoring setup, including the data acquisition system, additional on-site equipment, required corrections to improve data quality for high frequencies, data management and remote-processing facilities used to analyse the measured data. The choice and installation of electrodes, cables and measurement configurations are discussed and quality parameters are used for the continuous assessment of system functioning and data quality. Exemplary analysis results of the first season of operation highlight the importance of continuous quality control. It is also found that proper cable elevation decreased capacitive leakage currents and in combination with the correction of inductive effects led to consistent tomographic results up to 1 kHz measurement frequency. Overall, the successful operation of an sEIT monitoring system over multiple months with multiple daily tomographic measurements was achieved.
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Suntrup III, Donald J., Timothy V. Ratto, Matt Ratto et James P. McCarter. « Characterization of a high-resolution breath acetone meter for ketosis monitoring ». PeerJ 8 (24 septembre 2020) : e9969. http://dx.doi.org/10.7717/peerj.9969.
Texte intégralRésumé :
Background The ketone bodies beta-hydroxybutyrate (BHB) and acetone are endogenous products of fatty acid metabolism. Although ketone levels can be monitored by measuring either blood BHB or breath acetone, determining the precise correlation between these two measurement methods has been challenging. The purpose of this study is to characterize the performance of a novel portable breath acetone meter (PBAM) developed by Readout, Inc., to compare single versus multiple daily ketone measurements, and to compare breath acetone (BrAce) and blood BHB measurements. Methods We conducted a 14-day prospective observational cohort study of 21 subjects attempting to follow either a low-carbohydrate/ketogenic or a standard diet. Subjects were asked to concurrently measure both blood BHB and BrAce five times per day and report the results using an online data entry system. We evaluated the utility of multiple daily measurements by calculating the coefficient of variation (CV) for each daily group of measurements. We calculated the correlation between coincident BrAce and blood BHB measurements using linear ordinary least squares regression analysis. We assessed the ability of the BrAce measurement to accurately predict blood BHB states using receiver operating characteristic (ROC) analysis. Finally, we calculated a daily ketone exposure (DKE) using the area under the curve (AUC) of a ketone concentration versus time graph and compared the DKE of BrAce and blood BHB using linear ordinary least squares regression. Results BrAce and blood BHB varied throughout the day by an average of 44% and 46%, respectively. The BrAce measurement accurately predicted whether blood BHB was greater than or less than the following thresholds: 0.3 mM (AUC = 0.898), 0.5 mM (AUC = 0.854), 1.0 mM (AUC = 0.887), and 1.5 mM (AUC = 0.935). Coincident BrAce and blood BHB measurements were moderately correlated with R2 = 0.57 (P < 0.0001), similar to literature reported values. However, daily ketone exposures, or areas under the curve, for BrAce and blood BHB were highly correlated with R2 = 0.80 (P < 0.0001). Conclusions The results validated the performance of the PBAM. The BrAce/BHB correlation was similar to literature values where BrAce was measured using highly accurate lab instruments. Additionally, BrAce measurements using the PBAM can be used to predict blood BHB states. The relatively high daily variability of ketone levels indicate that single blood or breath ketone measurements are often not sufficient to assess daily ketone exposure for most users. Finally, although single coincident blood and breath ketone measurements show only a moderate correlation, possibly due to the temporal lag between BrAce and blood BHB, daily ketone exposures for blood and breath are highly correlated.