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[IEEE 2018 International Carnahan Conference on Security Technology (ICCST) - Montreal, QC, Canada (2018.10.22-2018.10.25)] 2018 International Carnahan Conference on Security Technology (ICCST) - Reliable Leak Detection in Pipelines Using Integrated DdTS Temperature and DAS Acoustic Fiber-Optic Sensor
摘要： Reliable and early detection of leaks in pipelines transporting liquid or gas is highly desirable. In this work, two orthogonal technologies based on high-sensitivity fiber-optic distributed sensing were integrated into one system and tested for their effectiveness in actual field installations. The first technology is based on temperature difference detection using Distributed Differential Temperature Sensor (DdTS or DDTS). The second is based on Distributed Acoustic Sensor (DAS), which uses Coherent Optical Time-Domain Reflectometry (C-OTDR). DdTS can almost instantaneously detect a temperature difference in the optical fiber as low as 0.0005 οC, while C-OTDR can detect minute wide-bandwidth acoustic signals. Both technologies can detect the location of a leak to within a few meters. Experimental results for water and nitrogen gas leaks detected by the integrated system are presented for two different installations in the field – one where the cable was buried directly in the soil and another where the cable was buried in soil inside a 2” conduit for about 29 km. DdTS reliably detected leaks at both installations, while DAS detected leaks only when the cable was buried directly in soil. Test results show that the integration of both DdTS and DAS technologies can increase the probability of leak detection and minimize false/nuisance alarms. The integrated system also detected third party interference (TPI), thus providing a one-system solution for pipeline integrity monitoring and intrusion detection up to 40 km from a central location.
关键词： Oil and Gas Pipeline,DdTS,Leak Detection,Fiber Optics Sensor,DTS,TPI,DAS,C-OTDR
更新于2025-09-23 15:22:29
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Application of distributed temperature sensing for cracking control of mass concrete
摘要： This paper presents a framework of cracking control for a mass concrete structure in a reservoir project, by taking advantage of Distributed Temperature Sensing (DTS) system. The DTS system in this project, mainly consisting of an Optical Backscatter Reflectometer (OBR) interrogation unit and a single fibre-optic cable, was deployed to measure and monitor concrete temperatures of an intake tower in block placement. The temperature measurements in concrete blocks were utilized as the fundamental data to determine the thermal properties of the cast-in-situ concretes, through the inverse analysis method based on temperature simulation. Based on thermal stress simulation using the thermal properties, cracking risks of each concrete block were predicted and evaluated under the modes of temperature control associated with the time-varying construction and ambient conditions, for appropriate modes before and after the concrete placement. The framework of cracking control, developed by integrating the DTS measurement with the temperature forecast and the cracking prediction based on thermal stress simulation and cracking risk evaluation, improves the efficiency of temperature regulation and cracking control in mass concrete construction, and can be further integrated into the intelligent construction management of concrete projects.
关键词： Cracking control,Fibre-optic,DTS,Mass concrete
更新于2025-09-23 15:21:21
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A field study on the application of distributed temperature sensing technology in thermal response tests for borehole heat exchangers
摘要： Although the enhanced thermal response test (ETRT) method has been used to determine the distribution of ground temperatures and effective thermal conductivities, there are a number of obstacles which limit the wide application of this technology in the discipline of geoengineering. In this literature, four aspects of ETRT technology were investigated: (a) acquisition of ground temperature, (b) installation of the heat exchange tubes, (c) optimization of the monitoring positions, and (d) the difference in thermal conductivity obtained by the ETRT and numerical simulation. To investigate these issues, a field trial was carried out in Heze, Shandong Province, China, and the corresponding numerical models were built. The results demonstrate that: (i) the conventional methods that infer undisturbed ground temperature using water in tubes have large errors, whereas the distributed temperature sensing (DTS) technique enables the measurement of precise temperature profiles; (ii) the thermal conductivity measured using double U-tubes reflects the soil thermal property more accurately than that for a single U-tube; (iii) it is more reasonable to install optical fibers outside the U-tube sidewall than inside the observation tube; and (iv) it is essential to quantitatively consider various interface thermal impedance when estimating ground thermal conductivities using numerical simulation.
关键词： Fiber optic sensor,Distributed temperature sensing (DTS),Ground-coupled heat pump (GCHP),Thermal conductivity,Thermal response test (TRT)
更新于2025-09-23 15:21:01
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The Phase Behavior in the Active Layer of Small Molecule Organic Photovoltaics: The State Diagram of p-DTS(FBTTh <sub/>2</sub> ) <sub/>2</sub> :PC <sub/>71</sub> BM
摘要： A comprehensive study was undertaken to obtain a more fundamental understanding of the phase behavior of the p-DTS(FBTTh2)2:PC71BM system, used in small molecule organic solar cells, with a strong focus on the amorphous phase and its influence on crystallinity. Three dedicated thermal protocols were used in combination with advanced thermal analysis, solid-state NMR, and wide angle X-ray diffraction. Rapid cooling, to avoid structure formation and gain insight in the amorphous phase, and slow cooling, to promote structure formation, were used as limiting cases to explain the intermediate behavior after device processing from solution. A complete state diagram was developed and the glass transition (Tg) - composition relationship was determined. In the case of slow cooling and the procedure used for device processing, the rapid crystallization of p-DTS(FBTTh2)2 leads to an enrichment of the amorphous phase in PC71BM, increasing its Tg and causing vitrification of the mixed amorphous phase before crystallization when the total amount of PC71BM exceeds 70 wt%. The common processing additive 1,8-diiodooctane (DIO) was found to lead to a lower p-DTS(FBTTh2)2 crystallinity and smaller average crystal size. More importantly, it acts as a strong plasticizer, lowering Tg significantly and thus reducing the morphological stability of the p-DTS(FBTTh2)2:PC71BM mixtures.
关键词： p-DTS(FBTTh2)2:PC71BM,glass transition temperature,wide angle X-ray diffraction,phase behavior,crystallinity,amorphous phase,small molecule organic photovoltaics,thermal analysis,solid-state NMR,1,8-diiodooctane (DIO)
更新于2025-09-23 15:19:57
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Analysis of Seepage in a Laboratory Scaled Model using Passive Optical Fiber Distributed Temperature Sensor
摘要： Seepage is the key factor in the safety of dikes and earth‐fill dams. It is crucial to identify and localize the seepage excesses at the early stages before it initiates the internal erosion process in the structure. A proper seepage monitoring system should ensure a continuous and wide area seepage measurement. Here, continuous monitoring of seepage at the laboratory‐scale is achieved by a passive optical fiber Distributed Temperature Sensing (DTS) system. An experimental model was designed which consists of initially unsaturated sand model, water supply, seepage outflow, optical fiber DTS system, and water and air temperature measurement. Initially, the sand temperature was higher than the temperature of the seepage water. An optical fiber DTS system was employed with a high‐temperature resolution, short sampling intervals and short time intervals for temperature monitoring in the sand model. In the system, the small variation in the temperature due to groundwater flow was detected. The numerical analysis was conducted for both the seepage process and the heat transfer progression in the sand model. The results of the heat flow simulation were evaluated and compared with the measured temperature by the optical fiber DTS. Obvious temperature reduction was obtained due to seepage propagation in the sand. The rate of temperature reduction was observed to be dependent on the seepage flow velocity.
关键词： flow velocity,optical fiber DTS,temperature,seepage,saturation
更新于2025-09-23 15:19:57
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Theoretical Study of a Class of Organic Da????a??A Dyes for Polymer Solar Cells: Influence of Various ??a??Spacers
摘要： A class of D‐π‐A compounds that can be used as dyes for applications in polymer solar cells has theoretically been designed and studied, on the basis of the dyes recently shown by experiment to have the highest power conversion efficiency (PCE), namely the poly[4,8‐bis(5‐(2‐(PBDTS‐TZNT) butylhexylthio)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b’]dithiophene‐2,6‐diyl‐alt‐TZNT] and poly[4,8‐bis(4‐fluoro‐5‐(2‐butylhexylthio)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b’]dithiophene‐2,6‐ diyl‐alt‐TZNT] (PBDTSF‐TZNT) substances. Electronic structure theory computations were carried out with density functional theory and time‐dependent density functional theory methods in conjunction with the 6?311G (d, p) basis set. The PBDTS donor and the TZNT (naphtho[1,2‐c:5,6‐c]bis(2‐octyl‐[1,2,3]triazole) acceptor components were established from the original substances upon replacement of long alkyl groups within the thiophene and azole rings with methyl groups. In particular, the effects of several π‐spacers were investigated. The calculated results confirmed that dithieno[3,2‐b:2′,3′‐d] silole (DTS) acts as an excellent π‐linker, even better than the thiophene bridge in the original substances in terms of well‐known criteria. Indeed, a PBDTS‐DTS‐TZNT combination forms a D‐π‐A substance that has a flatter structure, more rigidity in going from the neutral to the cationic form, and a better conjugation than the original compounds. The highest occupied molecular orbital (HOMO)‐lowest unoccupied molecular orbital (LUMO) energy gap of such a D‐π‐A substance becomes smaller and its absorption spectrum is more intense and red‐shifted, which enhances the intramolecular charge transfer and makes it a promising candidate to attain higher PCEs.
关键词： DFT calculations,PCEs,DTS,PBDTS‐TZNT and PBDTSF‐TZNT,D‐π‐A dyes,polymer solar cells
更新于2025-09-23 15:19:57
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Performance enhancement of conjugated polymer-small molecule-non fullerene ternary organic solar cells by tuning recombination kinetics and molecular ordering
摘要： We present our study of conjugated polymer-small molecule (SM)-non-fullerene ternary organic solar cells (OSCs), which employs conjugated polymer PTB7-Th and small molecule p-DTS(FBTTh2)2 as donors and non-fullerene molecule IEICO-4F as an acceptor. It is observed that the power conversion efficiency (PCE) of ～10.9% for PTB7-Th: p-DTS(FBTTh2)2: IEICO-4F ternary OSCs with 15 wt% of p-DTS(FBTTh2)2 SM is higher than PCE of ～9.8% for PTB7-Th: IEICO-4F OSCs. Morphological studies confirm that the addition of p-DTS(FBTTh2)2 SM in PTB7-Th: IEICO-4F binary blend improves molecular ordering and crystallinity of PTB7-Th due to the favorable interaction with p-DTS(FBTTh2)2 thereby providing 3-D textured structures consisting of a mixture of edge-on and face-on orientations. The improved molecular ordering is shown to enhance exciton generation rate, exciton dissociation, charge collection, and to reduce charge recombination, all of which boosts the PCE.
关键词： PTB7-Th,Ternary,p-DTS(FBTTh2)2,IEICO-4F,GIWAXS,Non-fullerene
更新于2025-09-23 15:19:57
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Distributed Fiber Sensing and Dynamic Rating of Power Cables || Optical Fibers, Connectors, and Cables
摘要： This chapter introduces the types of fibers available in the industry for DTS applications, the types of optical connectors, and their relevance in the context of distributed sensing applications. It also discusses how they may be incorporated into power cable transmission land and submarine corridors as well as the potential challenges that one may encounter during installation, particularly when fibers are embedded in the power cable itself.
关键词： Installation challenges,Connectors,Submarine corridors,DTS applications,Distributed sensing,Optical Fibers,Power cable transmission,Cables
更新于2025-09-11 14:15:04
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Compressed-sensing (CS)-based Image Deblurring Scheme with a Total Variation Regularization Penalty for Improving Image Characteristics in Digital Tomosynthesis (DTS)
摘要： In this work, we considered a compressed-sensing (CS)-based image deblurring scheme with a total-variation (TV) regularization penalty for improving image characteristics in digital tomosynthesis (DTS). We implemented the proposed image deblurring algorithm and performed a systematic simulation to demonstrate its viability. We also performed an experiment by using a table-top setup which consists of an x-ray tube operated at 90 kVp, 6 mAs and a CMOS-type flat-panel detector having a 198-μm pixel resolution. In the both simulation and experiment, 51 projection images were taken with a tomographic angle range of θ=60o and an angle step of Δθ=1.2o and then deblurred by using the proposed deblurring algorithm before performing the common filtered-backprojection (FBP)-based DTS reconstruction. According to our results, the image sharpness of the recovered x-ray images and the reconstructed DTS images were significantly improved and the cross-plane spatial resolution in DTS was also improved by a factor of about 1.4. Thus the proposed deblurring scheme appears to be effective for the blurring problems in both conventional radiography and DTS and is applicable to improve the present image characteristics.
关键词： Compressed-sensing (CS),Deblurring,Digital tomosynthesis (DTS),Total variation (TV)
更新于2025-09-11 14:15:04
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Modeling of Quench Behavior of YBa<formula><tex>$_{2}$</tex></formula>Cu<formula><tex>$_{3}$</tex></formula>O<formula><tex>$_{7-\delta}$</tex></formula> Pancake Magnets and Distributed Temperature Sensing-based Quench Detection for Operating Temperature 30 K - 77 K
摘要： A two-dimensional/three-dimensional (2-D/3-D) mixed electrothermal model is proposed for the simulation of quench behavior of high-temperature superconducting (HTS) pancake magnets, where a 2-D electrothermal model is proposed to simulate the YBa2 Cu3 O7 -δ (YBCO) subcoil and is coupled with the remaining parts of the YBCO magnet, which are treated as 3-D homogeneous coils. For operating temperature from 30 to 77 K, the quench behavior of four YBCO pancake coils (two Kapton-insulated coils and two TiO2 -insulated coils) are simulated. Thermal equilibrium states are found for both Kapton- and TiO2 -insulated coils. The thermal conductivity of insulating materials (Kapton, TiO2 ) significantly affects the equilibrium temperature profiles (ETPs) and the minimum quench energy (MQE), especially for relatively high operating temperature (e.g., 65–77 K). The distributed-temperature-sensing-based (DTS-based) quench detection criterion can be established on ETPs. The effect of the thickness of insulating materials on ETPs and MQEs is relatively weak, especially under relatively low operating temperature. The key parameters of ETP-based quench detection criterion, such as the reference temperature, the peak temperature, and the minimum normal zone size, are obtained for the operating temperature from 30 to 77 K.
关键词： quench detection criterion,Distributed temperature sensing (DTS),high-temperature superconducting (HTS) magnet,quench simulation,minimum quench energy (MQE)
更新于2025-09-10 09:29:36