337 research outputs found
Spatial temperature measurements and turbulence analysis using DTS in the LIAISE field campaign
No full textExperiments using fiber-optical set-ups for distributed temperature sensing (DTS) were conducted in the LIAISE (Land surface Interactions with the Atmosphere over the Iberian Semi-arid Environment) field campaign during 15-30 July 2021 in the north-east of Spain. Three DTS set-ups were installed to measure temperature profiles along varying vertical scales; 1.6 - 40 m in the atmosphere, 0 - 1 m into the rapidly-growing alfalfa canopy and -0.5 - 0 m in the soil. Measurements were conducted at 5 s and 25.4 cm resolutions using a 1.6 mm Kevlar-reinforced fiber. The preliminary data of these three set-ups are described in the first part of this thesis, which display the potential of using DTS in a land surface campaign to capture vertical temperature structure in great detail.A fourth fiber-optic set-up was installed with a horizontal extent of 70 m, measuring at four heights between 0.40 m and 2.05 m height. A thinner 0.5 mm cable was used here in an effort to obtain the fastest possible time response in order to measure temperature turbulence parameters using DTS. Measurements were made at 1 Hz and 12.7 cm resolution, however the actual sampling frequency appeared to be 0.15 Hz in the temperature spectrum, likely because of the long response time of the cable.Despite the limited 0.15 Hz sampling rate it was possible to obtain turbulence information through the use of the structure parameter of temperature, C2T. This parameter indicates the intensity of temperature fluctuations and was calculated over time, as is conventional. In a novel approach, it was also calculated over space, using the spatio-temporal dataset as obtained by DTS. Both the definition of C2T and the inertial range of the temperature spectrum were used to determine C2T. The spatial C2T obtained throughthe definition method was found to have the best correlation with a sonic anemometer reference, with an R2 of 0.88. The temporal C2T lack the structure that is shown in the spatial C2T, which is likely due to 30-min averaged data for horizontal wind speed from the sonic anemometer or to Taylor’s frozen turbulence hypothesis not being a suitable assumption within the dimensions of this research. Determining C2T through the turbulent spectrum was successful for limited data points for the time series, and is currently inconclusive for the spatial series.Recommendations for further research for using DTS in turbulence analysis are to investigate the effect of instrument noise and the limited sampling rate. Also a critical look into the current DTS calibration routines for atmospheric is recommended. This work provides a first step towards using DTS in capturingturbulent information along spatial temperature series.LIAISECivil Engineering | Environmental Engineerin
Verifying the BR-DTS method with hand measurements executed with the PT-100 and the Eddy Covariance method
No full textWithin hydrology evaporation is one of the most important terms in the water- and land surface energy balance. However evaporation is difficult to estimate accurately. Conventional techniques to measure actual evaporation have their drawbacks. One of the main drawbacks is that multiple sensors need to be used, with all their own bias. One of these techniques, the Eddy Covariance (EC) system has the drawback that it is dependent on weather conditions and is known for its problems with closure of the energy balance (Foken, 2008). A new method called the Bowen Ratio- Distributed Temperature Sensing (BR-DTS) method is introduced by Euser et al. (2014). This method determines the Bowen ratio which is the ratio between the sensible heat flux and the latent heat flux. The BR-DTS method measures temperature using a fiber optic cable. This cable is placed vertically along a tower, the cable going up is dry and the cable going down is wrapped in cotton and kept wet. With the dry and wet temperature of the DTS-cable the air temperature and vapour pressure can be determined. By having a large amount of measurements over the height and measuring it with a single sensor the BR-DTS method does not have the problem of varying biases of sensors (Euser et al. 2014). The aim of this study is at first to verify if the temperature data of the dry and wet cable are correct and second to compare the outcome with the EC data. The temperature of the dry and wet cable measured with the BR-DTS method are really close to the temperatures measured with the relative humidity sensors with a maximum R2 of 0.998 at 4 and 16 meter height for the dry cable and a maximum R2 of 0.988 at 16 meter height for the wet cable. The energy gap found is relatively small, see figure 11, and the latent heat flux measured with the BR-DTS setup is just as in the results from B. Schilperoort (2015) greater than the latent heat flux measured with the EC setup. On the other hand the sensible heat flux measured with the BR-DTS setup is smaller than the sensible heat flux measured with the EC setup which is in contradiction with the results from B. Schilperoort (2015).Civil Engineering and GeosciencesWater Managemen
Development and initial evaluation of the molar incisor hypomineralisation early detection and intervention training module (MIH-EDIT) for dental therapists / Sarah Lim Wan-Lin
No full textIn Malaysia, dental therapists (DTs) are uniquely positioned to assist with molar incisor hypomineralisation (MIH) early detection and intervention. However, existing literature has highlighted that majority of DTs have not received sufficient training in this area. The objectives of this study were to 1) develop and implement the MIH-EDIT among DTs; 2) assess DTs’ awareness about MIH and aspects on continuous education at baseline; 3) compare DTs’ perception towards MIH and confidence in MIH early detection and intervention before (T0) and immediately after implementing the MIHEDIT (T1); 4) compare DTs’ knowledge scores (KS) and 5) scores for MIH detection using photographic scoring (PS) at T0, T1 and two weeks after implementing the MIHEDIT (T2) and 6) determine the association between DTs’ sociodemographic characteristics (SC) and their KS and PS at T1. This study was divided into two phases: Phase I (Development) and Phase II (Implementation and Evaluation). In Phase I, module content development and validation, consensus photographic scoring, questionnaire adaptation and pilot study were systematically carried out until all module materials and study instruments were finalised. In Phase II, the MIH-EDIT e-booklet was distributed and a 1-day training using pre-recorded presentation slides with live question and answer (Q&A) sessions was implemented among DTs in Sarawak. DTs answered the questionnaire and MIH detection using photographic scoring at T0, T1 and T2. Besides descriptive statistics, DTs perception and confidence at T0 - T1 (McNemar test), KS and PS at T0, T1 and T2 (repeated measures ANOVA) were compared. Association (independent sample t test/ one way ANOVA and ANCOVA) between DTs’ SC and their KS and PS at T1 were determined. The MIH-EDIT was first developed and then implemented among 187 DTs (89.9% response rate). At baseline, only 31.3% reported receiving information regarding MIH and 79.5% were keen for further training. There was a significant increase in the proportion of positive responses for all questions related to perception towards MIH and confidence in MIH early detection and intervention from T0 - T1 (p0.05) was found between DTs’ SC and their mean KS at T1 whereas the mean PS for DTs who had a clinical job scope (21.35�}4.89) was significantly higher (p=0.025) compared to those who had a nonclinical job scope (18.62�}5.57) at T1. Within the study limitations, the MIH-EDIT immediately improved DTs perception towards MIH and confidence in MIH early detection and intervention. The MIH-EDIT increased DTs knowledge level on MIH and improved their ability to detect MIH over the short-term. Knowledge-wise, the MIHEDIT was suited to all DTs regardless of their SC. However, DTs with a clinical job scope performed better in the MIH detection using photographic scoring
Non-invasive water content estimation in a tuff wall by DTS
No full textUndesired presence of water in historical masonries has a negative effect on the walls and causes deterioration of decorative works covering the walls, such as frescoes and valuable plasters. To prevent this, non-invasive moisture measurements are needed that avoid damage during masonry inspection caused by sample taking or probe insertion. Active heated distributed temperature sensing (DTS) with optical fibres is widely used in hydrology to assess soil moisture content. The aim of this study is to examine the potential of this technique for non-invasive water content measurements in a real scale wall. The tested masonry is made of yellow Neapolitan tuff bricks, a material widely used in historical buildings of Campania (Southern Italy). Distributed temperature measurements are carried out with three different heating strategies (different power and duration) during the drying process following the complete saturation of the wall. The acquired temperature data are then processed with three different methods (estimators), so to identify the best combination of heating strategy and data processing approach. Despite the presence of a significant bias, it is possible to identify relationships between the gravimetric moisture content and the different estimators. Those relationships are influenced to a large degree by the thermal contact between the DTS cable and the masonry. This research shows it is possible to measure water content in tuff masonry using non-invasive active heated fibre optic cable when establishing good thermal contact between the cable and the masonry.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Water Resource
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Technical Note: Bed conduction impact on fiber optic DTS water temperature measurements
No full textError in Distributed Temperature Sensor (DTS) water temperature measurements may be introduced by contact of the fiber optic cable sensor with bed materials (e.g., seafloor, lakebed, stream bed). Heat conduction from the bed materials can affect cable temperature and the resulting DTS measurements. In the Middle Fork John Day River, apparent water temperature measurements were influenced by cable sensor contact with aquatic vegetation and fine sediment bed materials. Affected cable segments measured a diurnal temperature range reduced by 10% and lagged by 20–40 min relative to that of ambient stream temperature. The diurnal temperature range deeper within the vegetation–sediment bed material was reduced 70% and lagged 240min relative to ambient stream temperature. These site-specific results illustrate the potential magnitude of bed-conduction impacts with buried DTS measurements. Researchers who deploy DTS for water temperature monitoring should understand the importance of the environment into which the cable is placed on the range and phase of temperature measurements.This discussion paper has been under review for the journal Geoscientific Instrumentation, Methods and Data Systems (GI). Please refer to the corresponding final paper in GI. The published article is copyrighted by the author(s) and published by Copernicus Publications on behalf of the European Geosciences Union. The published article can be found at: http://www.geoscientific-instrumentation-methods-and-data-systems.net/ The final revised paper is available at: http://hdl.handle.net/1957/5657
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Stalemate and 'DTS' depth to stalemate endgame tables
No full textStalemating the opponent in chess has given rise to various opinions as to the nature of that result and the reward it should properly receive. Here, following Lasker and Reti, we propose that ‘stalemate’ is a secondary goal, superior to a draw by agreement or rule – but inferior to mate. We report the work of ‘Aloril’ who has created endgame tables holding both ‘DTM’ depth to mate and ‘DTS’ depth to stalemate data, and who should be regarded as the prime author of this paper. Further, we look at the classification of ‘Chess Stalemate Studies’ in the context of a ‘Lasker Chess’ which recognises the stalemate goal
The use of DTS systems for temperature logging in deep boreholes
No full textTitle: The use of DTS systems for temperature logging in deep boreholes. Author: Václav Štěpánek Department: Institute of Hydrogeology, Engineering Geology and Applied Geophysics Supervisor: Mgr. Petr Dědeček, Ph.D., GFÚ AV ČR Abstract: The signifcance of deep geothermal energy is progressively growing, similar to the extraction of unconventional oil and gas reserves, which involves the drilling of deviated wells in regions with elevated temperatures. Temperature measurements play a fundamental role in exploration, drilling, and subsequent monitoring, with equipment evolving due to technological advancements, particu- larly in temperature measurement capabilities. The aim of this thesis is to focus on a Distributed Temperature Sensing (DTS) system that utilizes fber optic technology for temperature logging. Specifcally, these fber optic sensors enable continuous profle measurements in real time, which is well-suited for capturing dynamic changes in the temperature feld. Simultaneously, fber optic cables demon- strate durability and reliability, making them suitable for permanent installations in high-temperature, high-pressure, and highly corrosive environments. The resul- ting variability in deployment enables adaptation within the measurement context. In deep borehole measurements, the DTS can be..
The use of DTS systems for temperature logging in deep boreholes
No full textTitle: The use of DTS systems for temperature logging in deep boreholes. Author: Václav Štěpánek Department: Institute of Hydrogeology, Engineering Geology and Applied Geophysics Supervisor: Mgr. Petr Dědeček, Ph.D., GFÚ AV ČR Abstract: The signifcance of deep geothermal energy is progressively growing, similar to the extraction of unconventional oil and gas reserves, which involves the drilling of deviated wells in regions with elevated temperatures. Temperature measurements play a fundamental role in exploration, drilling, and subsequent monitoring, with equipment evolving due to technological advancements, particu- larly in temperature measurement capabilities. The aim of this thesis is to focus on a Distributed Temperature Sensing (DTS) system that utilizes fber optic technology for temperature logging. Specifcally, these fber optic sensors enable continuous profle measurements in real time, which is well-suited for capturing dynamic changes in the temperature feld. Simultaneously, fber optic cables demon- strate durability and reliability, making them suitable for permanent installations in high-temperature, high-pressure, and highly corrosive environments. The resul- ting variability in deployment enables adaptation within the measurement context. In deep borehole measurements, the DTS can be...Název práce: Využití systému DTS pro teplotní měření v hlubokých vrtech Autor: Václav Štěpánek Katedra: Ústav hydrogeologie, inženýrské geologie a užité geofyziky Vedoucí bakalářské práce: Mgr. Petr Dědeček, Ph.D., GFÚ AV ČR Abstrakt: Využívání hlubinné geotermální energie postupně nabývá na svém významu, obdobně jako získávání nekonvenčních zásob ropy a zemního plynu, které čím dál častěji vyžaduje vrtání ukloněných vrtů v místech zvýšených teplot. Nedílnou součástí průzkumu, vrtání a následného monitoringu je i teplotní měření, kdy používané zařízení procházejí v důsledku technologického pokroku změnami, spojenými především s novými možnostmi v oblasti teplotní karotáže. V této souvislosti se práce věnuje systému distribuovaného měření teploty (DTS), který využívá technologie optických vláken. Tyto optovláknové senzorické systémy umož- ňují především nepřetržité proměřování profilu, a to v reálném čase, čímž jsou ideální pro snímání dynamických změn v teplotním poli. Zároveň jsou optické kabely mechanicky velmi odolné, a tedy i vhodné pro trvalé instalace v podmín- kách vysokých teplot, tlaků, ale i ve vysoce korozivním prostředím. Následná variabilita zapojení umožňuje přizpůsobení se v kontextu daného měření, kdy v případě měření v hlubokých vrtech je DTS možné instalovat takovým způsobem, aniž by stálo...Ústav hydrogeologie, inženýrské geologie a užité geofyzikyInstitute of Hydrogeology, Engineering Geology and Applied GeophysicsPřírodovědecká fakultaFaculty of Scienc
Machine learning and digital twins: monitoring and control for dynamic security in power systems
No full textThe reader of the chapter will be able to connect techniques from machine learning (ML) and digital twins (DTs) to gain insights for monitoring and control of (dynamic) security for electrical power systems. DTs are validated and verified high-fidelity (hf) models providing high simulation accuracy. DTs can be used for simulation of the supervised process of system operation and are therefore able to provide synthetic studied data, where measurement data are scarce. However, for some real-time applications in monitoring and control, such high-fidelity simulation models are not appropriate due to the corresponding computational barrier. There, ML aims to create an application-specific, low-fidelity (lf) approximation of the digital twin. Such trained lf models are used in real-time applications where computational time is scarce and lf information is sufficient. The conceptual intersection of hf and lf models has been little explored and becomes increasingly complex. This chapter aims to provide a conceptual overview of how such hf and lf models can be combined. This chapter is split into two parts where the first part is to introduce ML, lf models, and digital twins, hf models, for power systems analysis, and the second chapter is to use these two types of models to form purpose-driven surrogate lf models, illustrated on the example of dynamic security assessment (DSA). In the first part, the concepts for using DTs as hf models for online power system studies and their corresponding tuning of model parameters are introduced. Subsequently, ML i.e., lf models, are introduced and their corresponding training frameworks. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Electrical Power Grid
Using Distributed Temperature Sensing (DTS) for Locating and Characterising Infiltration and Inflow into Foul Sewers before, during and after Snowmelt Period
No full textInfiltration and inflow (I/I) into sewers cause negative effects on the sewer system,wastewater treatment plant and environment. Identifying the causes and locating the inflows isnecessary in order to address the I/I problem. This paper focuses on using distributed temperaturesensing (DTS) for identifying, locating and characterising I/I into a sewer system during the endof winter–beginning of summer transition period under dry and wet weather conditions. Duringsnowmelt, several locations with I/I were identified, while these locations did not show I/I duringstorm events after the snowmelt. In addition, during a very heavy storm after the snowmelt period,I/I was found at other locations. Therefore, DTS was demonstrated to be effective in identifying thetype of I/I and in locating I/I. Finally, I/I monitoring campaigns in cold climates should take intoaccount the variety of pathways of I/I during snowmelt and during rainfall.Validerad;2019;Nivå 2;2019-08-19 (marisr)</p
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