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Zhou, HF, LJ Lu, ZY Li i YQ Ni. "Performance of videogrammetric displacement monitoring technique under varying ambient temperature". Advances in Structural Engineering 22, nr 16 (3.01.2019): 3371–84. http://dx.doi.org/10.1177/1369433218822089.
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There has been an increasing number of attempts to apply videogrammetric technique to displacement measurement of civil engineering structures. Its potentials in structural health monitoring have also gained more attention. This study carried out an investigation on the effect of temperature variation on the measurement accuracy of videogrammetric technique in an effort to examine its feasibility for structural health monitoring. Long-term indoor videogrammetric measurement tests have been conducted, and the performance of the videogrammetric displacement monitoring technique under ambient temperature conditions has been examined. The results show that temperature variations cause non-negligible errors in measured displacements. In line with the temperature variation, the displacement measurement error also contains not only daily fluctuation pattern but also overall trend. In terms of daily fluctuation pattern, the horizontal measurement error and temperatures of vision measurement system are in satisfactory consistency, while the vertical measurement error does not coincide well with temperatures of vision measurement system. In terms of overall trend, the vertical measurement error is highly correlated with temperatures of vision measurement system, while the horizontal one is almost uncorrelated with temperatures of vision measurement system. As an outcome of the dominance of overall trend in the temperature variation over a long time period, the vertical measurement error and temperatures of vision measurement system conform to a favorable linear relationship, while the horizontal measurement error tends to be constrained in a small range when the temperatures of vision measurement system exceed a certain value.
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SATO, Masahiko, Naoki TAMURA i Hisataka TANAKA. "D12 Transient Temperature Variation beneath Rake Face in End Milling(Monitoring of machining process)". Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21 2009.5 (2009): 457–60. http://dx.doi.org/10.1299/jsmelem.2009.5.457.
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Todoran, Tudor Paul, i Mugur Ciprian Balan. "Ground Temperature Variation around the Horizontal Collectors of a Heat Pump". Applied Mechanics and Materials 659 (październik 2014): 481–86. http://dx.doi.org/10.4028/www.scientific.net/amm.659.481.
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The manuscript presents results of a 3 years experiment concerning the monitoring of temperature variation around a horizontal collector, coupled to a ground – water heat pump. Ground temperature was monitored in 7 (seven) measurement points: 1 (one) in the center of the collector area and 6 (six) at 15 cm, 30 cm and 60 cm of the collector boundary. The data processing methodology, described in the manuscript, allowed corrections, comparison with natural ground temperature variation and calculation of important characteristics of temperature variation in each measurement point. The main obtained results are: minimum, maximum and average temperatures, dates when minimum, maximum and average temperatures were reached, amplitude of temperatures variations and deviations comparing to natural ground temperature variation. The study of temperature field allowed the complete characterization of the ground temperature variation, including spatial and temporal variation. Some practical conclusions of the study are also presented in the manuscript. It was highlighted that due to a correct calculation of the collectors field size and to the presence of snow in each heating season of the 3 (three) years of the experiment, the ground temperature did not decreased below 2°C and the ground temperature recovered uniformly after each non heating season.
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Wen, Tao, Zheng Hu, Yankun Wang, Zihan Zhang i Jinshan Sun. "Monitoring and Analysis of Geotemperature during the Tunnel Construction". Energies 15, nr 3 (20.01.2022): 736. http://dx.doi.org/10.3390/en15030736.
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High geotemperatures are encountered during tunnel construction in areas with complex geological structures, which can seriously affect personnel and equipment in the process of tunnel construction and operation. The Nige tunnel, a deep-buried extra-long tunnel, was selected to monitor the geotemperature during construction. The air, rock, and water temperatures during the tunnel construction were measured at the tunnel face, and the actual temperatures of the rock or water body at the tunnel face were measured by advanced drilling. The variation trends of the water temperature, air temperature, and flow of water with the tunnel mileage were analyzed. The differences in three measured rock temperatures in three advanced drillings were revealed. The results showed that the Nige tunnel had a maximum water temperature of 63.4 °C, maximum rock temperature (Rock T) of 88.8 °C, and maximum air temperature (Air T) of 56.4 °C. Increasing trends of the air, rock, and water temperatures with the tunnel’s horizontal distance and the buried depth (vertical depth) were obvious, and the geotemperature gradient was approximately 7.6 °C per 100 m. Additionally, the variation laws of the construction ambient temperature with time in a complete construction cycle showed four stage characteristics, and each stage presented different mathematical relationships. These findings will provide guidance for the construction of high geotemperature tunnels in future.
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Banerjee, Tathagata, i Sumedha Moharana. "Monitoring thermal defects in rail and rail joints using piezo impedance-based structural health monitoring (PISHM)". Engineering Research Express 4, nr 1 (10.02.2022): 015014. http://dx.doi.org/10.1088/2631-8695/ac4e9a.
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Abstract Rail track derailment has been proven to be the cause of most of the rail accidents in recent years. High-temperature strains in railways caused by rail traction and thermal variation are the main causes of derailment, which lead to buckling. The likelihood of passenger deaths and maintenance costs will be reduced if thermal strains and failure in rails are detected early. This research attempts to provide a preventative strategy for detecting thermal strains and deformation caused by temperature fluctuations at railways. Using the electromechanical impedance (EMI) technique, piezoelectric sensors were used to acquire piezo coupled structural signatures for lab-sized rail samples, i.e. plain rail and rail joints, for gradual temperature escalation and repeat heat cycle. The experimental conductance signatures were obtained for the incremental rise in temperature (30–80 °C) in ambient conditions, and repetitive thermal cycles. To better diagnose structural problems induced only by the effect of heat on the host structure, thermal compensation is proposed. The piezo–coupled signatures for thermal changes in rail and rail junctions (weld and bolt) were found to be particularly effective in detecting incipient structural alterations for both steady and cyclic temperature variations. Statistical damage index was used to quantify the damage for all types of rail-joint bar caused due to temperature variation. Overall, this study has paved an experimental technique that can be used to detect early damage in rail and rail joints due to thermal loading.
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Berry, R. J., A. D. Kennedy, S. L. Scott, B. L. Kyle i A. L. Schaefer. "Daily variation in the udder surface temperature of dairy cows measured by infrared thermography: Potential for mastitis detection". Canadian Journal of Animal Science 83, nr 4 (1.12.2003): 687–93. http://dx.doi.org/10.4141/a03-012.
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The daily and within-day variation in udder temperature was monitored in dairy cows (n = 10) using infrared thermography (IRT). The initial assessment and prediction of udder surface temperature variation would hopefully form the basis for future development of an early detection method for mastitis. Our initial objective was to determine the magnitude and pattern of udder temperature variation. To accomplish this, we measured daily fluctuations in udder temperature and the influence of environmental factors upon these values in non-mastitic cows. Udder temperature rose significantly after an exercise period (P < 0.05). Within-day monitoring of udder temperature demonstrated there was a distinct circadian rhythm. Lag regression analysis showed that previous daily udder temperatures together with environmental temperature parameters could successfully predict current udder temperature with a high degree of accuracy. The variation between predicted and actual udder temperature was within the detectable range for an inflammatory response. Infrared thermography shows promise in its application if coupled with environmental temperature monitoring as an early detection method for mastitis. Key words: Thermography, dairy cattle, environment, temperature
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Moreddu, Rosalia, Mohamed Elsherif, Haider Butt, Daniele Vigolo i Ali K. Yetisen. "Contact lenses for continuous corneal temperature monitoring". RSC Advances 9, nr 20 (2019): 11433–42. http://dx.doi.org/10.1039/c9ra00601j.
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Wu, Junpeng, Jian Cai, Jiyuan Yang, Jian Zhang i Zhiquan Zhou. "A High Reliability Damage Imaging Method Under Environmental Temperature Variations". Journal of Physics: Conference Series 2184, nr 1 (1.03.2022): 012036. http://dx.doi.org/10.1088/1742-6596/2184/1/012036.
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Abstract In Lamb wave-based structural health monitoring (SHM), the environmental temperature variations can easily affect Lamb wave monitoring signals and seriously reduce the reliability of final damage detection results. To resolve the temperature effect problem, a temperature compensation method of improved baseline signal stretch (IBSS) is presented and applied for high reliability damage imaging under large environmental temperature variations in this paper. After the basic principle of IBSS is analyzed, the realization of IBSS is discussed. Then, a IBSS-based high reliability damage imaging method under temperature variation situation is developed. An experimental study is finally arranged.
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Rose, Mark A., i John W. White. "SPATIAL AND TEMPORAL TEMPERATURE VARIATION IN A GREENHOUSE". HortScience 25, nr 9 (wrzesień 1990): 1114e—1114. http://dx.doi.org/10.21273/hortsci.25.9.1114e.
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Temperature affects all major plant physiological processes. Traditional methods of controlling greenhouse temperatures use aerial sensors that do not monitor temperatures within each component of the soil-plant-atmosphere continuum.Bench, pot, plant canopy, and aerial temperatures were monitored using thermocouples and thermistors processed by environmental computers during a wide range of greenhouse conditions. These include diurnal cycles of high and low solar radiation, night periods with and without artificial lighting, and various ventilation and heating conditions. Spatial temperature gradients of 10-22 °C were discovered during both day and night conditions. These spatial variations cause significant differences in average temperatures between and within benches over diurnal and even seasonal cycles.Preliminary surveys of microclimatic variations that occur within the greenhouse experimental area are essential for choosing the proper experimental design. Continuous environmental monitoring during the experiment is necessary for interpreting experimental results.
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Huynh, Thanh-Canh, Young-Hwan Park, Jae-Hyung Park, Dong-Soo Hong i Jeong-Tae Kim. "Effect of Temperature Variation on Vibration Monitoring of Prestressed Concrete Girders". Shock and Vibration 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/741618.
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The effect of temperature variation on vibration monitoring of prestressed concrete (PSC) girders is experimentally analyzed. Firstly, vibration features such as autoregressive (AR) coefficient, correlation coefficient of power spectral density (CC of PSD), natural frequency, and mode shape are selected to estimate the effect of temperature variation on vibration characteristics of PSC girders. Secondly, vibration experiments on a lab-scale PSC girder are performed under the condition of temperature variation. Finally, the vibration features with respect to the temperature variation are analyzed to estimate the effect of temperature in vibration characteristics of the PSC girder.
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Carvajal Rodriguez, Felipe Andrés, Luis Augusto Koenig Veiga i Wilson Alcântara Soares. "Temperature Acquisition System for Real Time Application of First Velocity Correction by EDM (Electronic Distance Measurement)". Geoplanning: Journal of Geomatics and Planning 8, nr 1 (20.05.2021): 61–74. http://dx.doi.org/10.14710/geoplanning.8.1.61-74.
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The first velocity correction is used to correct the measured distance affected by the velocity variation of the electromagnetic wave propagation in a medium. This correction depends on the refractive index of the propagation medium and reference refractive index. The influence of the temperature in the medium refractive index is critical; some estimates establish that variation 1°C causes 1ppm of error in distances. In the measuring processes with total stations, the temperature is usually collected at only one point, for example, in the position where the measuring instrument is setup. However, the wave propagates in a medium of non-constant temperature, where the extremes of the line can present variations and thus this measurement in only one point could be non-representative. In this context, it was developed a low-cost real-time temperature acquisition system. This system provides the temperature values in different locations allowing their monitoring through the time. Experiments realized during the geodetic monitoring of a dam, show variations up to 8°C among geodetic points on the dam and around it. An analysis was development to evaluate the influence of temperature variations on monitoring distances and geodetic coordinate of a 2d network with different approaches (temperature modeling). The results shows different values for distances (1.0 mm) and coordinates (0.5 mm) depending of the approach choose.
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Ehrlich, P. F., G. Vedulla, N. Cottrell i P. A. Seidman. "Monitoring intraoperative effectiveness of caudal analgesia through skin temperature variation". Journal of Pediatric Surgery 38, nr 3 (marzec 2003): 386–89. http://dx.doi.org/10.1053/jpsu.2003.50113.
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Zhou, Yi, i Limin Sun. "Insights into temperature effects on structural deformation of a cable-stayed bridge based on structural health monitoring". Structural Health Monitoring 18, nr 3 (5.06.2018): 778–91. http://dx.doi.org/10.1177/1475921718773954.
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Structural deformation is an important consideration in the health monitoring of bridges, and its dependence on temperature variations is quite complex. Based on field measurements performed for an operational cable-stayed bridge, the proposed study investigates mechanisms of thermally induced variations in girder length and mid-span deflection through plane geometric and finite element analyses. The objective of this study is to understand the behaviour of such bridges over annual and diurnal cycles. It has been observed that the girder length and mid-span deflection of a cable-stayed bridge exhibit different modes of the temperature–response correlation. Thermally induced changes in girder length are solely governed by the average girder temperature, and its annual variation in amplitude is significantly larger compared to the diurnal variation. However, thermally induced mid-span deflections are simultaneously influenced by the cable temperature and average girder temperature, and these do not vary monotonously with temperature, thereby resulting in nearly equal variation amplitudes over both annual and diurnal cycles. Temperature-induced deformations of a cable-stayed bridge could well be approximated through multiple linear superposition of thermal-expansion effects of individual components. Besides thermal-expansion coefficients of structural materials, the temperature dependency of mid-span deflection of a symmetrical twin-tower cable-stayed bridge is closely related to the ratio of tower height above the deck to central span of the girder as well as span ratio of the side span to central span. The proposed simplified formulae to estimate the sensitivities of temperature effects could be readily extended to other cable-stayed bridges with different geometric arrangements, thereby providing valuable insights into thermally induced deformation of such bridges.
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Lopes, Thiago Glissoi, Renata Maia Rocha, Paulo Roberto Aguiar, Felipe Aparecido Alexandre i Thiago Valle França. "Evaluating Temperature Influence on Low-Cost Piezoelectric Transducer Response for 3D Printing Process Monitoring". Proceedings 42, nr 1 (14.11.2019): 26. http://dx.doi.org/10.3390/ecsa-6-06571.
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The 3D printing process deals with the production of three-dimensional objects with defined geometries. However, this manufacturing process has a crucial point established at the beginning of the object manufacturing, where anomalies can occur and compromise the entire object produced. The piezoelectric diaphragm has been studied as an alternative to the conventional acoustic emission (AE) sensor concerning the monitoring of structures and processes. It has in its assembling a ceramic element with piezoelectric properties, which makes its response sensitive to temperature variations. The Pencil Lead Break (PLB) method is widely used due to its efficiency in the characterization of AE sensors. The present work aims to study the influence of temperature on the piezoelectric diaphragm response for the monitoring of the 3D printing process. PLB tests were performed on the glass surface of a 3D printer at three different temperatures, and the raw signal was collected at 5 MHz sample rate. The signal was investigated in the time and frequency domain. The results demonstrate that the frequency response of the sensor is directly influenced by the temperature variations. In addition, the signal amplitude variations occur differently along the entire spectrum, and frequency bands with small and large amplitude variations can be selected for a comparison study. Furthermore, two frequency bands were carefully selected, and the mean error was obtained regarding the reference temperatures of 25 and 45 °C. It can be inferred that the piezoelectric transducer has low sensitivity to temperature variation if a proper frequency band is selected, where an acceptable error of 16.9% was obtained.
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Sepehry, N., M. Shamshirsaz i F. Abdollahi. "Temperature variation effect compensation in impedance-based structural health monitoring using neural networks". Journal of Intelligent Material Systems and Structures 22, nr 17 (13.09.2011): 1975–82. http://dx.doi.org/10.1177/1045389x11421814.
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In this article, a new method for temperature compensation on the basis of artificial neural networks (ANNs) in impedance-based structural health monitoring (ISHM) has been introduced. ISHM using piezoelectric wafer active sensors (PWAS) has been extensively developed to provide detection of fault in structure. The principle of this method is based on the electromechanical coupling effect of PWAS materials. Any change in structure leads to changes in mechanical impedance of structure. The electrical impedance of PWAS can sense this change by the electromechanical coupling effect of PWAS. Therefore, the difference in this electrical impedance for undamaged and damaged structures can be considered as a damage index to detect the damage in structure. Since physical and mechanical properties of structure also PWAS materials are temperature dependent, so this electrical impedance of PWAS will be affected by temperature changes. Consequently, the variation in environmental or service temperatures can be detected erroneously as damage in ISHM method. In this article, a new method using ANN based on radial basis function (RBF) has been proposed and developed to compensate the temperature effect on the damage index. A steel plate and gas pipe with bolted joints are considered as two case studies for the performance evaluation of the proposed fault detection methodology. Results confirm that the proposed method using the ANN can be effectively utilized to compensate temperature variation for damage detection in different structures.
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Li, Gao, Fubiao Zhou, Zhandong Su, Jingshan Bo, Xiang Chen i Chi Li. "In Situ Research on the Spatiotemporal Variations in the Temperature and Deformation of Aeolian Sand-Modified Soil Roadbed Constructed in Cold Regions". Advances in Civil Engineering 2022 (12.08.2022): 1–18. http://dx.doi.org/10.1155/2022/7323463.
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Aiming at the cracking phenomenon of an aeolian sand-modified soil roadbed in an actual project near Tongliao city in eastern Inner Mongolia, Northeast China, an in situ test was conducted. Temperature-compensated fiber Bragg grating (FBG) strain sensors and moisture sensors were embedded into the test roadbed to monitor and observe the relationships between the temperature, moisture, and deformation of the roadbed with respect to variations in climate conditions in such a cold region. For the core issues of roadbed soil deformation and impact on the project, two climate conditions, namely, temperature and rainfall, were taken as external factors, while the temperature and moisture of the roadbed soil were taken as internal factors controlling the deformation and failure of the roadbed soil. A correlation analysis of the test roadbed monitoring data showed that the roadbed soil moisture was weakly affected by environmental conditions. The roadbed soil temperature was independent of the rainfall but was significantly related to air temperature variation (the correlation coefficient ranged from 0.6301 to 0.8926). Limited by the boundary conditions of the roadbed, the response of the variation in the roadbed soil temperature to the air temperature variation gradually weakened from the shallow surface to the deeper parts and the lag in the roadbed soil temperature variation relative to the air temperature variation became more evident. A correlation analysis of the monitoring data of the roadbed soil deformation, soil temperature, and soil moisture showed that the roadbed soil moisture had a weak correlation with the roadbed soil temperature. The roadbed soil deformation was independent of the soil moisture but was strongly related to the roadbed soil temperature. Therefore, the strain of the test roadbed could reflect the roadbed deformation as temperature deformation. The temperature deformation of the roadbed superficial soil was significantly greater than that of the deep soil.
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Liu, Tao, Tao Jiang, Gang Liu i Changsen Sun. "Transfer-Learning-Based Temperature Uncertainty Reduction Algorithm for Large Scale Oil Tank Ground Settlement Monitoring". Sensors 24, nr 1 (29.12.2023): 215. http://dx.doi.org/10.3390/s24010215.
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Sensors operating in open-air environments can be affected by various environmental factors. Specifically, ground settlement (GS) monitoring sensors installed in oil tanks are susceptible to non-uniform temperature fields caused by uneven sunshine exposure. This disparity in environmental conditions can lead to errors in sensor readings. To address this issue, this study aimed to analyze the impact of temperature on GS monitoring sensors and establish a mapping relationship between temperature uncertainty (fluctuations of measurement caused by temperature variation) and temperature variation. By collecting the temperature information and inferring the temperature uncertainty being introduced, this interference can be removed. However, it is crucial to note that in real-world complex scenarios, the relationship between temperature uncertainty and temperature variation is not always a constant positive correlation, which limits the data available for certain periods. Moreover, the limited availability of data presents a challenge when analyzing the complex mapping relationship. To overcome these challenges, a transfer-learning-based algorithm was introduced to develop a more accurate model for predicting temperature uncertainty based on temperature variation, even with limited data. Subsequently, a practical test was conducted to validate the proposed algorithm’s performance. The results demonstrated that the algorithm outperformed a simple linear fitting model using the least squares method (LSM), achieving an improvement of up to 21.9%. This outcome highlights the algorithm’s potential for enhancing the performance of GS sensors in daytime monitoring and contributing to the safe operation of oil tank facilities and infrastructure health monitoring.
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Pathak, Prasad, Pranav Pandya, Sharvari Shukla, Aamod Sane i Raja Sengupta. "A Sensor Placement Strategy for Comprehensive Urban Heat Island Monitoring". ISPRS International Journal of Geo-Information 12, nr 1 (30.12.2022): 11. http://dx.doi.org/10.3390/ijgi12010011.
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Urban heat islands (UHIs) increase the energy consumption of cities and impact the health of its residents. In light of the correlation between energy consumption and health and UHI variations observed at a local level within the canopy layer, satellite-derived land surface temperatures (LSTs) may be insufficient to provide comprehensive information about these deleterious effects. For both LST and air temperatures to be collected in a spatially representative and continuous manner, and for the process to be affordable, on-ground temperature and humidity sensors must be strategically placed. This study proposes a strategy for placing on-ground sensors that utilizes the spatial variation of measurable factors linked to UHI (i.e., seasonal variation in LSTs, wind speed, wind direction, bareness, and local climate zones), allowing for the continuous measurement of UHI within the canopy layer. As a representative city, Pune, India, was used to demonstrate how to distribute sensors based on the spatial variability of UHI-related variables. The proposed method may be helpful for any city requiring local-level observations of UHI, regardless of the climate zone. Further, we evaluate the placement of low-cost technology sensors that use LoRaWAN technology for this purpose, in order to overcome the problem of high costs associated with traditional in-situ weather stations.
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Shan, Wenchen, Xianqiang Wang i Yubo Jiao. "Modeling of Temperature Effect on Modal Frequency of Concrete Beam Based on Field Monitoring Data". Shock and Vibration 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/8072843.
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Temperature variation has been widely demonstrated to produce significant effect on modal frequencies that even exceed the effect of actual damage. In order to eliminate the temperature effect on modal frequency, an effective method is to construct quantitative models which accurately predict the modal frequency corresponding to temperature variation. In this paper, principal component analysis (PCA) is conducted on the temperatures taken from all embedded thermocouples for extracting input parameters of regression models. Three regression-based numerical models using multiple linear regression (MLR), back-propagation neural network (BPNN), and support vector regression (SVR) techniques are constructed to capture the relationships between modal frequencies and temperature distributions from measurements of a concrete beam during a period of forty days of monitoring. A comparison with respect to the performance of various optimally configured regression models has been performed on measurement data. Results indicate that the SVR exhibits a better reproduction and prediction capability than BPNN and MLR models for predicting the modal frequencies with respect to nonuniformly distributed temperatures. It is succeeded that temperature effects on modal frequencies can be effectively eliminated based on the optimally formulated SVR model.
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Ghorat, Mohsen, Gevork B. Gharehpetian, Hamid Latifi, Maryam A. Hejazi i Mehdi Bagheri. "High-Resolution FBG-Based Fiber-Optic Sensor with Temperature Compensation for PD Monitoring". Sensors 19, nr 23 (30.11.2019): 5285. http://dx.doi.org/10.3390/s19235285.
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This paper presented a new sensor to detect and localize partial discharge (PD) in power transformers based on a fiber Bragg grating (FBG). The fundamental characteristics of the proposed sensor, as a PD detector, were temperature compensation and direction independence. The proposed high-resolution PD detector operated based on the FBG wavelength shift. It is necessary to evaluate the physical parameters of the sensor to achieve the best results. Therefore, in this paper, the detected signal strength was investigated for different angles and temperatures. A Teflon hollow mandrel and two FBGs attached to the inner and outer surfaces of the hollow mandrel were chosen as the inner transformer PD detector. The changes in the sensor output were less than 0.4 mV and 0.5 mV for direction variations and a temperature variation of 14 °C (degrees Celsius), respectively. Consequently, the proposed sensor could be successfully employed for the detection of a transformer PD signal.
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Doubenskaia, Maria, Sergey Grigoriev, Ivan Zhirnov i Igor Smurov. "Parametric analysis of SLM using comprehensive optical monitoring". Rapid Prototyping Journal 22, nr 1 (18.01.2016): 40–50. http://dx.doi.org/10.1108/rpj-04-2014-0046.
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Purpose – This paper aims to propose methods for on-line monitoring and process quality assurance of Selective Laser Melting (SLM) technology as a competitive advantage to enhance its implementation into modern manufacturing industry. Design/methodology/approach – Monitoring of thermal emission from the laser impact zone was carried out by an originally developed pyrometer and a charge-coupled device (CCD) camera which were integrated with the optical system of the PHENIX PM-100 machine. Experiments are performed with variation of the basic process parameters such as powder layer thickness (0-120 μm), hatch distance (60-1,000 μm) and fabrication strategy (the so-called “one-zone” and “two-zone”). Findings – The pyrometer signal from the laser impact zone and the 2D temperature mapping from HAZ are rather sensible to variation of high-temperature phenomena during powder consolidation imposed by variation of the operational parameters. Research limitations/implications – Pyrometer measurements are in arbitrary units. This limitation is due to the difficulty to integrate diagnostic tools into the optical system of a commercial SLM machine. Practical implications – Enhancement of SLM process stability and efficiency through comprehensive optical diagnostics and on-line control. Originality/value – High-temperature phenomena in SLM were monitored coaxially with the laser beam for variation of several operational parameters.
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Baral, Sushmita, Prateek Negi, Sailesh Adhikari i Suresh Bhalla. "Temperature Compensation for Reusable Piezo Configuration for Condition Monitoring of Metallic Structures: EMI Approach". Sensors 23, nr 3 (1.02.2023): 1587. http://dx.doi.org/10.3390/s23031587.
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This paper presents a novel algorithm for compensating the changes in conductance signatures of a piezo sensor due to the temperature variation employed in condition monitoring using the electro-mechanical impedance (EMI) approach. It is crucial to consider the changes in an EMI signature due to temperature before using it for comparison with the baseline signature. The shifts in the signature due to temperature can be misinterpreted as damages to the structure, which might also result in a false alarm. In the present study, the compensation values are calculated based on experiments on piezo sensors both in a free boundary condition and in a bonded condition on a metallic host structure. The values were further validated experimentally for damage detection on a large 2D steel plate structure. The variation in first natural frequency values for the unbonded piezo sensor at different temperatures has been used to develop the compensation algorithms. Whereas, in the case of the bonded sensor, the shift in structural peaks has been used. The developed compensation relations showed promising results in damage detection. Lastly, a finite element-based study has also been performed, supporting the experimental findings. The outcome of this study will aid in the compensation of the signatures in the structure due to temperature variation in the conductance signature.
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Watson, D. K., i RKND Rajapakse. "Seasonal variation in material properties of a flexible pavement". Canadian Journal of Civil Engineering 27, nr 1 (15.02.2000): 44–54. http://dx.doi.org/10.1139/l99-049.
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Seasonal variation of temperature and moisture causes considerable changes in the load-carrying capacity of pavements in geographical areas subjected to extreme freeze/thaw conditions. The Seasonal Monitoring Program (SMP) of the Long Term Pavement Performance (LTPP) study of the Federal Highway Administration (FHWA) monitors seasonal variations in Falling Weight Deflectometer (FWD) deflections, air temperature, rainfall, soil temperature, moisture content, and soil electrical resistance at numerous sites across North America. This study relates changes in pavement load carrying capacity represented by the pavement layer resilient moduli to selected environmental factors for a test pavement site in southwestern Manitoba. The significant environmental parameters causing seasonal variation in pavement layer resilient moduli are identified as the surface temperature for the asphalt layer and the thawing index for base and subgrade layers. The resilient moduli of various pavement layers show a substantial decrease in magnitude with increasing values of respective environmental parameter. The present model can be used for preliminary verification of empirical pavement design and rehabilitation practices currently in use to account for seasonal variations. Key words: asphalt, backcalculation, falling weight deflectometer, freezing, pavements, moisture, resilient moduli, seasonal variation, thawing, temperature.
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Nilesh M. Patil, P M. Krishna, G. Deena, C Harini, R.K. Gnanamurthy i Romala V. Srinivas. "Exploring real-time patient monitoring and data analytics with IoT-based smart healthcare monitoring". Scientific Temper 14, nr 04 (27.12.2023): 1196–201. http://dx.doi.org/10.58414/scientifictemper.2023.14.4.21.
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This research study endeavours to explore the dynamic temporal variations in patient health parameters, specifically heart rate, temperature, and Systolic Blood Pressure (SBP), within the context of a synthetic patient dataset. The analysis of heart rate data revealed distinct patterns of temporal variation, characterized by cyclic fluctuations within each hour and an overall increasing trend over the observation period. These findings Highlights the influence of circadian rhythms, potential associations with physical activity and stress, and the broader physiological implications for patient health. The examination of temperature data exhibited analogous cyclic patterns and an increasing trend, prompting considerations of circadian rhythms and external factors such as environmental temperature and physiological health. Conversely, SBP data demonstrated fluctuations without a discernible trend, highlighting the complex nature of blood pressure regulation and its susceptibility to a myriad of physiological and external influences. This study provides a foundational understanding of patient health parameter dynamics and emphasizes the need for more extensive research to elucidate the underlying mechanisms and clinical implications. The insights gleaned from this investigation hold the potential to inform healthcare practitioners and researchers in the realms of patient monitoring and personalized healthcare, ultimately enhancing the quality of patient care and decision-making in clinical settings.
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Abouellail, A. A. "THERMOELECTRIC MONITORING OF THERMAL RESISTANCE IN ELECTRONIC SYSTEMS". Eurasian Physical Technical Journal 20, nr 3(45) (21.09.2023): 52–61. http://dx.doi.org/10.31489/2023no3/52-61.
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The article proposes to apply the method of thermoelectric testing to determine the thermophysical parameters of the thermal interface. A thermal interface is located between metal surfaces, between which, thermoelectromotive force occurs during heating at any stage of the device operation. The obtained graphs of the temperature difference dependence on the heating time, measured by thermocouples, and measured using thermoelectromotive force confirm the accuracy of the thermoelectric method of testing. Graphs visualize the heat transfer process with thermal resistance variation, temperature fluctuations and the resulting thermoelectromotive force. The proposed method makes it possible to monitor thermal resistance with an error of less than 8 %.
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Miesner, F., A. Lechleiter i C. Müller. "Reconstructing bottom water temperatures from measurements of temperature and thermal diffusivity in marine sediments". Ocean Science 11, nr 4 (9.07.2015): 559–71. http://dx.doi.org/10.5194/os-11-559-2015.
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Abstract. Continuous monitoring of oceanic bottom water temperatures is a complicated task, even in relatively easy-to-access basins like the North or Baltic seas. Here, a method to determine annual bottom water temperature variations from inverse modeling of instantaneous measurements of temperatures and sediment thermal properties is presented. This concept is similar to climate reconstructions over several thousand years from deep borehole data. However, in contrast, the presented method aims at reconstructing the recent temperature history of the last year from sediment thermal properties and temperatures from only a few meters depth. For solving the heat equation, a commonly used forward model is introduced and analyzed: knowing the bottom water temperature variations for the preceding years and the thermal properties of the sediments, the forward model determines the sediment temperature field. The bottom water temperature variation is modeled as an annual cosine defined by the mean temperature, the amplitude and a phase shift. As the forward model operator is non-linear but low-dimensional, common inversion schemes such as the Newton algorithm can be utilized. The algorithms are tested for artificial data with different noise levels and for two measured data sets: from the North Sea and from the Davis Strait. Both algorithms used show stable and satisfying results with reconstruction errors in the same magnitude as the initial data error. In particular, the artificial data sets are reproduced with accuracy within the bounds of the artificial noise level. Furthermore, the results for the measured North Sea data show small variances and resemble the bottom water temperature variations recorded from a nearby monitoring site with relative errors smaller than 1 % in all parameters.
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Küsel, Frank, Elsabe Kearsley, Liam J. Butler, Sarah A. Skorpen i M. Z. E. B. Elshafie. "Measured temperature effects during the construction of a prestressed precast concrete bridge beam". MATEC Web of Conferences 199 (2018): 11013. http://dx.doi.org/10.1051/matecconf/201819911013.
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Prestress losses in precast concrete beams include the short-term effects of elastic shortening and the long-term effects of concrete shrinkage, concrete creep and steel relaxation. Temperature effects are, however, excluded. The aim of this research was to monitor the behaviour of a prestressed precast concrete bridge beam, focussing on temperature effects and destressing. Successful monitoring assists in comparing the real performance of a structure to the expected design performance, and in managing the durability of the monitored structure. The effect of temperature variation on strains in prestressed beams was investigated by instrumenting a precast beam. Temperature and strains were monitored from the day of casting up to and including the cutting of the pretensioning strands. Daily temperature variations causing vertical non-linear temperature profiles resulted in internal strains of up to 28 % of the strains caused by destressing. It was therefore concluded that thermal effects before destressing resulting from elevated curing temperatures and daily temperature changes should be considered in the calculation of prestress losses. The monitoring techniques used were successful in determining the stresses and strains within the beam, which can be used to compare real prestress losses with the losses assumed in design.
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Shi, Yu Liang, Ming Dong Chen i Min Li. "Comparing of Temperature Variation with Different Types Greenhouse". Advanced Materials Research 594-597 (listopad 2012): 2128–31. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.2128.
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Greenhouse temperature of the three different types was measured under sunny winter weather conditions. The variation regularity of greenhouses temperature with outdoor temperature was studied according to the monitoring data of experimental greenhouse, which was different roof and floor structure. The results showed that the greenhouse temperature of the herringbone roof construction higher than the greenhouse of the serration roof construction; the greenhouse temperature of the serration roof construction is higher than the greenhouse of arch roof construction. Through analysis of temperature variation on the different type greenhouse, it will provide theoretical basis to construct greenhouse in different areas.
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Nelson, C. F., i L. D. Nelson. "107 UNEXPLAINED VARIATION IN EMBRYO FREEZER DIGITAL READOUT". Reproduction, Fertility and Development 24, nr 1 (2012): 166. http://dx.doi.org/10.1071/rdv24n1ab107.
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Differences among frozen embryo transfer results are often observed but are usually unexplainable. One cause of possible variability in pregnancy rates could be faulty digital readout of the biological freezer unless adequate controls are routinely used. By monitoring temperatures throughout the freezing process independently of the freezer readout, differences between the embryo freezer digital readout (EFDR) vs thermocouple (TC) and digital thermometer (DT) were observed when using a Bio Cool II Alcohol Freezer. The difference between EFDR and actual temperature (TC and DT) ranged from –4.9°C to +5.4°C. To further investigate possible causes of these differences, electrical supply to the freezer and ambient temperatures were monitored at 21 different on-the-farm locations. Ranges of voltage (117–124.4), Hz (59.96–60.00), mA (10.82–11.90) and ambient temperature (–6.1°C to +23.9°C) were recorded. However, no correlations between the EFDR and voltage (r = 0.097), Hz (r = –0.227), mA (r = 0.140), or actual temperature (r = –0.350) were found (P > 0.05). Two freezing procedures were done in unheated barn areas where the ambient temperature was –6.1°C and –4.9°C, with readout differences of +1.7°C and –0.8°C, respectively. Six of the 21 differences were ≥+2.0°C and 4 differences were ≤–2.0°C. The variable EFDR was apparently a problem within the freezer itself. In practice the real temperature (TC and DT) was used to determine the seeding temperature, therefore eliminating the chance of seeding at highly variable temperatures (–10°C to –2°C). The readout difference remained consistent throughout the freezing process and did not affect the freezing curve. It is suggested that any laboratory instrument be independently monitored to ensure quality control.
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Liu, Ping, Wentao Shi, Bo Sun, Qian Wang, Xiaokun Xie i Changqing Li. "Characteristics of the Temperature and Humidity Variations of Burial-Type Stone Relics and a Fitting Model". Applied Sciences 14, nr 5 (5.03.2024): 2157. http://dx.doi.org/10.3390/app14052157.
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Burial stone relics remain in a humid, semi-enclosed environment for long periods, and temperature and humidity variations can cause deterioration acceleration. Yang Can’s tomb was selected as the research object, and field monitoring and simulations were performed to investigate the characteristics of temperature and humidity variations, after which the simulation results were evaluated. The monitoring results showed that solar radiation, rainfall, wind speed, and depth of entry are important factors affecting the variation in the temperature and humidity of burial stone relics. The temperature outside the chamber is greatly affected by seasonal variations, while the humidity inside the chamber is influenced by seasonal variations, so appropriate measures should be implemented inside and outside the chamber during different seasons to alleviate deterioration. On the basis of the above analysis, a temperature and humidity model for the interior chamber of burial stone relics was established in COMSOL software 5.6, combined with a porous medium heat transfer model and computational fluid dynamics (CFD) model. The temperature and humidity inside the chamber can be calculated by the temperature and humidity outside the chamber. This study provides data support for hydrothermal, condensation and other related studies of burial stone relics.
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Khan, Zakir Hossain. "Relation Among Temperature, Salinity, pH and DO of Seawater Quality". Technium: Romanian Journal of Applied Sciences and Technology 2, nr 4 (29.05.2020): 39–45. http://dx.doi.org/10.47577/technium.v2i4.777.
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Worldwide coastal and marine resources provide a wide range of essential ecological, economic and social benefits. Temp (OC), pH, Salinity (ppt) and DO (mg/L) measured monthly at sampling point of seawater for twelve months monitoring period in the Bay of Bengal to monitor the variation of selected parameters at six selected locations near Moheshkhali Upazila of Cox’s Bazar District. Water samples collected from a depth of 0.5m. Temperature, pH, Salinity and DO levels and variation of respective monitoring location found consistent for a twelve months monitoring period. While temperature decreased, salinity increased at all sampling locations. It was also observed that, DO decreased, while temperature increased for twelve months monitoring period. Temperature of seawater of the Bay of Bengal found in a rage of 20OC to 30OC, pH found in a range of 7.6 to 8.3, Salinity measured in a range of 13ppt to 32ppt and DO measured in a range of 6.0mg/l to 7.9mg/l.
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Hermenean, Ioana Sinziana, Ion Visa, Anca Duta i Dorin Valentin Diaconescu. "MODELING TEMPERATURE VARIATION IN A CPV SYSTEM". Environmental Engineering and Management Journal 10, nr 2 (2011): 263–69. http://dx.doi.org/10.30638/eemj.2011.039.
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Zegeye Teshale, Eyoab, Dai Shongtao i Lubinda F. Walubita. "Evaluation of Unbound Aggregate Base Layers using Moisture Monitoring Data". Transportation Research Record: Journal of the Transportation Research Board 2673, nr 3 (marzec 2019): 399–409. http://dx.doi.org/10.1177/0361198119833681.
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The behaviors of unbound aggregate base (UAB) and subgrade layers are considerably affected by seasonal moisture fluctuations which ultimately affect both their load-bearing capacity and the overall performance of the pavement structure. As part of an effort towards designing optimal performing pavements, this study was undertaken to evaluate, characterize, and quantify the effects of moisture and temperature variations on UAB and subgrade materials commonly used in Minnesota. The scope included analyses of subsurface moisture and temperature measurements and characterization of moisture variation in multiple instrumented pavement sections. Key findings indicated that dense-graded aggregate base materials with high quality crushed aggregates and lower fine particles were more resistant to seasonal moisture variations. By contrast, the subbase and subgrade materials exhibited considerable sensitivity to seasonal moisture variations. The subgrade layers, in particular, were found to operate in fully saturated conditions for more than half of their service life. Overall, the study results are a valuable contribution to establishing guidelines for laboratory testing and designing optimal performing pavement structures.
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Lakshmi Narayanan, Sabarigirivasan, i Umamaheswari Nambiappan. "Long-Term Impacts of Temperature Gradients on a Concrete-Encased Steel I-Girder Experiment—Field-Monitored Data". Buildings 13, nr 3 (16.03.2023): 780. http://dx.doi.org/10.3390/buildings13030780.
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This article delves into an investigation of an experimental steel I-girder section encased in concrete and its instrumentation for the purpose of analyzing temperature distributions in concrete bridges. The study aims to examine the effect of differing air temperatures and thermal loads resulting from solar radiation. Structural health monitoring sensors, including a range of temperature sensors, were connected with the girder to monitor the structural performance using the data acquisition system constantly. The collection of experimental data took place during an exceptionally cold season, and the results of the study revealed both the lateral and vertical distribution of thermal gradients, as well as the fluctuations in these gradients over time. On the premise of the accumulated thermal data, empirical equations were suggested in order to forecast peak lateral as well as vertical temperature gradients, in accordance with the girder’s highest daily and lowest mean temperatures. This temperature variation may lead to longitudinal expansion and contraction in the structure during seasonal variations.
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Kosugi, Akira, Iwao Matsuya i Ikuo Ihara. "Feasibility Study on Noncontact Monitoring of Temperature Distributions of Rotating Tool". Applied Mechanics and Materials 372 (sierpień 2013): 336–39. http://dx.doi.org/10.4028/www.scientific.net/amm.372.336.
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In the fields of materials science and engineering, measuring temperature has become one of the most fundamental and important issues. In particular, there are growing demands for monitoring temperature gradient and its transient variation of materials being processed at higher temperatures because the temperature state during processing crucially influences the quality of final products. Such temperature monitoring is also required for rotating machining processes such as tuning, milling and friction stir welding (FSW). In this work, a new noncontact method for monitoring temperature distribution of a heated rotating cylindrical object is presented. A laser-ultrasonic technique is employed in the method. Surface temperature measurements for the cylindrical object using the laser-ultrasonic technique and heat conduction analyses are combined together for making quantitative evaluation of temperature distribution in the radial direction of the cylindrical object. To demonstrate the feasibility of this method, an experiment with a steel cylinder of 100 mm in diameter rotating at 300 min-1 and heated up to 100 °C on the surface is carried out. A pulsed laser generator and a laser Doppler vibrometer are used for generating and detecting surface acoustic waves (SAWs) on the steel cylinder, respectively. Measured SAWs are used for determining both surface and internal temperatures of the cylinder. As a result, the estimated temperature distributions during heating almost agree with those measured by an infrared radiation camera.
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Liu, Ziying, Tianlai Yu, Ning Yan i Lipeng Gu. "Variation of Ground Temperature along the Stratum Depth in Ice-rich Tundra of Hinggan Mountains Region, NE China". Geosciences 10, nr 3 (15.03.2020): 104. http://dx.doi.org/10.3390/geosciences10030104.
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A pile foundation in a permafrost region is in a negative-temperature environment, so concrete is affected by the negative temperature of the surrounding soil. It not only affects the formation of concrete strength but also leads to engineering quality accidents in serious cases. With the support of the two permafrost bridge projects of the national highway from Beijing to Mohe in the Greater Khingan Mountains region, a systematic remote dynamic monitoring method for ground temperature in ice-rich tundra is proposed. Based on the actual measurement of temperature at different strata depths and the comprehensive consideration of surface temperature, terrestrial heat flux and other parameters, the ground temperature profile evolution in relation to depth in Greater Khingan was established. The theoretical ground temperature profile curve is similar to the measured profile. The results show that the variation trends of ground temperatures in relation to the strata depth at different monitoring sites is similar, and all show seasonal variation: From June to November, the ground temperature at different depths tends to be constant. From December to May, the ground temperature at any depth within the range of 0 to 5.5 m follows the curve of the cosine function. Below 5.5 m, the earth temperature no longer varies with depth. The research results can be used as reference for pile foundation construction in a negative-temperature environment in ice-rich tundra.
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Ji, Jun, i Hou De Han. "Inside Temperature Monitoring System of Marine Reefer Containers Based on RFID". Applied Mechanics and Materials 120 (październik 2011): 485–88. http://dx.doi.org/10.4028/www.scientific.net/amm.120.485.
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The inside temperature monitoring system of marine reefer containers based on RFID is developed to make up for the shortcomings that the traditional system only depended on supply air temperature or return air temperature of the container to reflect the cargo temperature. The RFID temperature collection tags, the RFID reader and the software are designed and developed. Results of the inside temperature monitoring experiment showed that the system featured multi-points real-time monitoring, 100% readability, long reading distance and rapid reflection of the temperature variation, which may effectively solute the problem of cargo damage caused by uneven temperature distribution inside the container.
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Gao, Lei, Baoquan Ji, Gangqiang Kong, Xu Huang, Mingkun Li i Ali H. Mahfouz. "Distributed Measurement of Temperature for PCC Energy Pile Using BOFDA". Journal of Sensors 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/610473.
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PCC energy pile is a new technology for sustainable development of urban areas. Learning and understanding the temperature variation of PCC energy pile are very important to its development and application. In this study, the Brillouin optical frequency domain analysis (BOFDA) technology is firstly used to measure the temperature variation of PCC energy pile from a model test. The aim is to provide an optical fiber sensing method for monitoring the temperature distribution of PCC energy pile. When the temperatures of circulating water are 70°C, 60°C, 50°C, and 40°C, the result shows that the temperatures of PCC energy pile under different conditions are measured well by the optical fiber sensor. It will help to master the temperature distribution and thermomechanical characteristic of PCC energy pile. It can also provide the important scientific and theoretical basis for the design and application of PCC energy pile.
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Andreev, V. G., A. V. Vedernikov, A. V. Morozov i V. A. Khokhlova. "Monitoring of temperature variation in the focal region of an ultrasonic transducer". Acoustical Physics 52, nr 2 (marzec 2006): 119–24. http://dx.doi.org/10.1134/s1063771006020011.
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Xu, Xiaohua, Jia Luo i Kefei Zhang. "An Analysis of the Structure and Variation of the Tropopause over China with GPS Radio Occultation Data". Journal of Navigation 64, S1 (14.10.2011): S103—S111. http://dx.doi.org/10.1017/s0373463311000336.
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The status of the tropopause has impact on weather phenomena and climate change occurring in the atmosphere of the Earth. The investigation of structure and variation of the tropopause plays a significant role in an in-depth understanding of water vapour exchange, mass and chemical materials across the tropopause, and their impacts on climate change and ecological environment. With the advantages of high vertical resolution, global coverage, unbiased instrumentation, and long-term stability, GPS Radio Occultation (RO) data is ideal for the monitoring of tropopause structure. In this research, GPS RO data from the two missions, CHAMP and COSMIC, were used to assess and analyse the temporal and spatial variations in tropopause heights and temperature over China. The consistency of the precision of the GPS temperature profiles derived from the two missions were also statistically validated. The two types of tropopause, i.e. the Lapse Rate Tropopause (LRT) and the Cold Point Tropopause (CPT), were determined from the GPS RO temperature profiles, and the trend of the variations in tropopause heights and temperatures of the two types of tropopause were compared and analysed.
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Jiang, Zhao Hui, Chun Sheng Wang, Jing Zhang, Yi Yue i Shao Wen Li. "Online Monitoring and Analysis of Plant Photosynthetic Physiology and Environmental Factors". Applied Mechanics and Materials 241-244 (grudzień 2012): 75–80. http://dx.doi.org/10.4028/www.scientific.net/amm.241-244.75.
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It is very important for researching the growth and cultivation of plants that real-time monitoring of photosynthetic physiology & environmental parameters and analysis of relationship between these parameters. In this paper, an indoor cultivated Michelia alba monitoring system was built, which could continuously monitor leaf's CO2 exchange rate, transpiration rate, air temperature and humidity, soil moisture, photosynthetically active radiation and other parameters in real time, and could also analyze the relationship between the photosynthetic physiological parameters and environmental parameters. The results show that the diurnal variation of indoor cultivated Michelia alba leaf's CO2 exchange rate presents a bimodal pattern, which shows a midday depression. The diurnal variation of photosynthetically active radiation presents a single pattern. The diurnal variation of air humidity presents a “ S ” pattern, but the overall variation is little. The environmental factors that influenced the Michelia alba photosynthetic physiological characteristics most greatly are the photosynthetically active radiation and temperature.
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Chaman, Shilpa. "Zigbee Based Temperature Monitoring and Controlling in Matlab". Asian Journal of Electrical Sciences 2, nr 1 (5.05.2013): 1–4. http://dx.doi.org/10.51983/ajes-2013.2.1.1858.
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Efficient design and implementation of wireless sensor network has become an emerging area of research in recent years, due to vast potential of sensor network enables application that connect the physical world to the virtual world. By networking large numbers of Zigbee sensor nodes, it is possible to obtain data about physical phenomena that was difficult or impossible to obtain in conventional ways. In this paper a wireless temperature sensing and controlling system for real time dynamics has been proposed. Variation in the temperature is recorded in the GUI window and proper controlling action is taken accordingly. An 8-bit Atmega16 [1] microcontroller has been used to interface the temperature sensor using the IEEE 802.15.4 standard, Zigbee protocol. Zigbee has the characteristics of low power consumption, low cost and self organizing features.
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Sun, Chang Jun, Shao Xu Huang, Ning Tang, Pan Pan i Shao Peng Wu. "Study on Low-Temperature Properties of Self-Monitoring Asphalt Concrete". Applied Mechanics and Materials 303-306 (luty 2013): 2495–500. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.2495.
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With the self-diagnosis function of the self-monitoring asphalt concrete, we can evaluate the health status of pavement according to feedback on the electrical signals when it is under variation load. In this paper, indirect tensile test and flexural modulus test were used to study the low-temperature properties of self-monitoring asphalt concrete. The test results show that the performance of self-monitoring asphalt concrete has a strong sense of temperature. The result of low-temperature properties provides a reference for the further study of self-monitoring asphalt concrete.
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Dai, Lingquan, Haibo Liu, Wei Li, Zhengyang Tang i Yang Xu. "Monitoring and analysis of vertical thermal structure of the Three Gorges Reservoir". E3S Web of Conferences 118 (2019): 03035. http://dx.doi.org/10.1051/e3sconf/201911803035.
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Water temperature plays a crucial role in water ecological environment both in the reservoir and downstream area. Three Gorges Project (TGP) is the largest hydraulic engineering in the world, and changes of water quality attract much more attention, especially in the thermal structure since impoundment. In order to clearly understand water temperature distribution after impoundment in the Three Gorges Reservoir (TGR), we monitored the temperature distribution of the Taipingxi section which was not far from the dam from early April to the end of July. According to the analyzing of the monitoring data of transverse and vertical temperature variation, we could find that the temperature mixed uniformly in transverse direction. Excepting April, there was basically had no temperature difference in vertical direction, even in April, the maximum temperature difference was only 1.39°C within 100 meters (April 22), the average temperature gradient was only 0.014°C/m; Both the temperature of water and atmosphere have similar variation tendency, but the response of the water temperature to atmosphere is delayed, especially the bottom water temperature. The result indicate that the reservoir has mixed thermal structure during impoundment phase, so the release temperature had little change after the impoundment, the work provide a scientific basis for the development of pollution control and ecological protection measure.
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Zhang, Xuehui, i Wout Broere. "Monitoring of Tidal Variation and Temperature Change-Induced Movements of an Immersed Tunnel Using Distributed Optical Fiber Sensors (DOFSs)". Structural Control and Health Monitoring 2023 (12.07.2023): 1–17. http://dx.doi.org/10.1155/2023/2419495.
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The short-term deformation behavior of immersed tunnels due to daily or monthly temperature changes and tidal variations is often not monitored but forms important input for a structural health assessment of the tunnel. In this study, distributed optical fiber sensors (DOFSs) are used to monitor the short-term (daily and monthly) deformation behavior of an immersed tunnel. Joint opening and the relative settlement differences between tunnel elements are monitored simultaneously at subhour intervals. Measurements show that the variation in the joint opening is strongly correlated with temperature change, and the joint gap has a tendency to open at low temperatures and to close at increasing temperatures. Simultaneously, the entire immersed section behaves more like a rigid body and moves upwards and downwards periodically due to tidal fluctuations in the river, with an observed vertical movement of slightly less than one millimeter. The tide also causes local tilting of tunnel segments, and this tilting behavior differs between winter and summer, which implies that the (seasonal) temperature-induced joint deformations affect the robustness of the tunnel to tidal loads. A soil-tunnel structure interaction analysis reveals that the cyclic vertical movement of the tunnel is driven by retardation of the tidal wave in deeper soil layers, which can be captured by a coupled flow model. This study provides new insights into the short-term deformation behavior of immersed tunnels.
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Xu, Shijie, Fengyuan Yu, Xiaofei Zhang, Yiwen Diao, Guangming Li i Haocai Huang. "Monitoring Thermal Exchange of Hot Water Mass via Underwater Acoustic Tomography with Inversion and Optimization Method". Remote Sensing 16, nr 6 (21.03.2024): 1105. http://dx.doi.org/10.3390/rs16061105.
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Thermal exchange of underwater water mass caused by marine heat wave is a hot point of research recently. In particular, because the water temperature observation along hot water mass transportation is hard work. Acoustic tomography is an advanced method to measure water temperature variations via sound signal transmission with multi-station network sensing. The 5 kHz frequency acoustic tomography used for observing water temperature variations caused by ocean heat waves is interesting work. In this paper, the numerical simulation of hot water mass is completed first, then floatation and diffusion of hot water mass in a simulation are monitored by acoustic tomography. A new inversion optimization method is proposed to obtain hot water mass transportation variations at two-dimensional temperature vertical profile. The proposed inversion method adds a regularized mode matrix and the optimization method adds the model correlation matrix to improve the results quality. The accuracy of inversion optimization results is compared and discussed, where the mean temperature error is less than 0.4 °C. Sensing water temperature variation of marine heat waves is verified via acoustic signal transmission and improved inversion optimization method. The water dynamical process observation is an application of acoustic tomography, which can be further used observe underwater environmental characteristics.
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Caputi, N., S. de Lestang, M. Feng i A. Pearce. "Seasonal variation in the long-term warming trend in water temperature off the Western Australian coast". Marine and Freshwater Research 60, nr 2 (2009): 129. http://dx.doi.org/10.1071/mf08199.
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Previous studies have demonstrated that one area of greatest increase in surface sea temperatures (SST) (0.02°C per year) in the Indian Ocean over the last 50 years occurs off the lower west coast of Australia, an area dominated by the Leeuwin Current. The present paper examines water temperature trends at several coastal sites since the early 1970s: two rock lobster puerulus monitoring sites in shallow water (<5 m); four sites from a monitoring program onboard rock lobster vessels that provide bottom water temperature (<36 m); and an environmental monitoring site at Rottnest (0–50 m depth). Two global SST datasets are also examined. These data show that there was a strong seasonal variation in the historic increases in temperature off the lower west coast of Australia, with most of the increases (0.02–0.035°C per year) only focussed on 4–6 months over the austral autumn–winter with little or no increase (<0.01°C per year) apparent in the austral spring–summer period. These increases are also apparent after taking into account the interannual variation in the strength of the Leeuwin Current. The warming trend results in a change to the seasonal temperature cycle over the decades, with a delay in the peak in the temperature cycle during autumn between the 1950s and 2000s of ~10–20 days. A delay in the timing of the minimum temperature is also apparent at Rottnest from August–September to October. This seasonal variation in water temperature increases and its effect on the annual temperature cycle should be examined in climate models because it provides the potential to better understand the specific processes through which climate change and global warming are affecting this region of the Indian Ocean. It also provides an opportunity to further test the climate models to see whether this aspect is predicted in the future projections of how increases will be manifest. Any seasonal variation in water temperature increase has important implications for fisheries and the marine ecosystem because it may affect many aspects of the annual life cycle such as timing of growth, moulting, mating, spawning and recruitment, which have to be taken into account in the stock assessment and management of fisheries.
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Constantin, S. C., G. Predusca i E. Diaconu. "Pressure, Temperature and Humidity Monitoring System Using the Arty Platform". Scientific Bulletin of Electrical Engineering Faculty 21, nr 2 (1.12.2021): 1–5. http://dx.doi.org/10.2478/sbeef-2021-0013.
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Abstract The paper aims to present the usefulness of Field Programmable Gate Array - based systems, the elasticity of hardware design for reuse, and the use of hardware and software resources. The proposed measurement system is a starting point for the design of a weather station capable of interpreting the variation of the size of atmospheric pressure, temperature, and humidity, which could make local weather predictions.
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Somma, Renato, Claudia Troise, Luigi Zeni, Aldo Minardo, Alessandro Fedele, Maurizio Mirabile i Giuseppe De Natale. "Long-Term Monitoring with Fiber Optics Distributed Temperature Sensing at Campi Flegrei: The Campi Flegrei Deep Drilling Project". Sensors 19, nr 5 (27.02.2019): 1009. http://dx.doi.org/10.3390/s19051009.
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Monitoring volcanic phenomena is a key question, for both volcanological research and for civil protection purposes. This is particularly true in densely populated volcanic areas, like the Campi Flegrei caldera, which includes part of the large city of Naples (Italy). Borehole monitoring of volcanoes is the most promising way to improve classical methods of surface monitoring, although not commonly applied yet. Fiber optics technology is the most practical and suitable way to operate in such high temperature and aggressive environmental conditions. In this paper, we describe a fiber optics Distributed Temperature Sensing (DTS) sensor, which has been designed to continuously measure temperature all along a 500 m. deep well drilled in the west side of Naples (Bagnoli area), lying in the Campi Flegrei volcanic area. It has then been installed as part of the international ‘Campi Flegrei Deep Drilling Project’, and is continuously operating, giving insight on the time variation of temperature along the whole borehole depth. Such continuous monitoring of temperature can in turn indicate volcanic processes linked to magma dynamics and/or to changes in the hydrothermal system. The developed monitoring system, working at bottom temperatures higher than 100 °C, demonstrates the feasibility and effectiveness of using DTS for borehole volcanic monitoring.
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Mahan, James, Andrew Young, Paxton Payton, Michael Bange i John Stout. "Effect of Differential Irrigation on Accumulation of Canopy Temperature-Based Heat Units in Cotton". Journal of Cotton Science 18, nr 2 (wrzesień 2014): 129–36. http://dx.doi.org/10.56454/qkhn3250.
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Agricultural management decisions are often timed on the basis of accumulated air temperature heat units (AT-heat unit) to coincide with crop growth and development. The relationship between AT-heat unit accumulation and crop development is affected by water deficits that alter the relationship between air and plant canopy temperature. Improved technology for monitoring canopy temperatures makes it possible to continuously monitor canopy temperature in production settings. The utility of cotton canopy temperature heat units (CT-heat unit) was assessed by comparing decadal (2000-2009) AT-heat unit variation with variation in CT-heat unit accumulation due to variable irrigation in 2009. Irrigation-induced variation in CT-heat units (1198-1416) was similar to the decadal variation in AT-heat units (1270-1508). Two heat unit-based management tools: 1) the assignment of irrigation crop coefficients and 2) the identification of a fiber thickening period were both found to be sensitive to irrigation-induced changes in CT-heat unit accumulation. The inclusion of CT-heat units resulted in variability in both indicators that reflected effects of irrigation and climate on plant performance. Inclusion of canopy temperature measurements in heat unit accumulation might improve the utility of heat units.