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Preparation of graphene oxide with large lateral size and graphene/polyimide hybrid film via in situ “molecular welding” strategy
摘要： In this letter, we report an "ultrasonication-free" direct exfoliation method to obtain graphene oxide with large lateral size (LGO). The average size of LGO sheets is about 50 lm * 50 lm. The g-LGO film shows a superior in-plane thermal conductivity after the graphitization treatment. Furthermore, the in situ "molecular welding", using polyimide (PI) to weld up the GO sheets, is conducted to improve the performance of hybrid thermal conducting film. The thermal conductivity of g-LGO/PI film is 1053.975 ± 8.762 W m-1 K-1, superior to that of the g-LGO film and g-SGO/PI. The direct preparation method to obtain GO with large lateral size, followed by such an in situ "molecular welding" strategy by PI, provides a promising way to fabricate graphene-based film for efficient thermal management.
关键词： Molecular welding,In situ polymerization,Large lateral size,Thermal properties,Carbon material
更新于2025-09-23 15:23:52
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A Novel Method for Compensating Temperature Measurement Error Caused by Dust Using Infrared Thermal Imager
摘要： The dust generated in industrial processes has a serious impact on the accuracy of infrared thermometry, which is also the main reason for the limited use of infrared industrial temperature measurement methods applications. To reduce the influence of dust on infrared temperature measurement, this paper proposes a new method for compensating measurement error caused by dust. Firstly, the source of temperature measurement error caused by dust is analyzed, and a compensation method, in which the dust transmittance is important but difficult to determine, is proposed based on the principle of infrared temperature measurement. Then, to solve the difficulty of determining dust transmittance, we define a spatial temperature level co-occurrence matrix and a neighboring temperature level dependence matrix which can be utilized to extract the infrared thermal image’s texture features affected by dust. Finally, by integrating stacked denoising auto-encoder with optimized parameters and support vector regression, a dust transmittance model is established to determine dust transmittance based on the extracted features. Experimental results indicate that the proposed compensation method can reduce the influence of dust on infrared thermal imager’s accuracy effectively.
关键词： temperature measurement,dust transmittance,dust,texture feature,Compensation model,infrared thermal imager
更新于2025-09-23 15:23:52
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Development of a solid-state position sensitive neutron detector prototype based on ?6Li-glass scintillator and digital SiPM arrays
摘要： Photomultiplier tubes (PMT) have been used extensively as the photodetector of choice in scintillation based detectors for cold and thermal neutrons. However, the limitations of PMT based scintillation neutron detectors such as their sensitivity to magnetic fields or their high operating voltages (> 1 kV) have triggered the search for alternative photodetectors for these applications. Silicon photomultipliers (SiPM) operate in the single photon regime, have lower operating voltages (~ 20 - 70 V) than PMTs and are insusceptible to magnetic field. Additional features of the SiPMs like their low production cost, compactness and higher readout rates make them a potential candidate to replace the photodetector part in these developments. Therefore, we are developing a scintillation neutron detector based on SiPM technology. The detector prototype with an active detection area of 13 cm × 13 cm is aimed to be used in the future at the TREFF instrument of the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching, Germany, for neutron reflectometry experiments. In this paper, we report the detector concept, its development and the simulation results for design optimization.
关键词： Geant4,Neutron scintillation detectors,Cold and thermal neutrons,Silicon Photomultipliers (SiPM)
更新于2025-09-23 15:23:52
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[IEEE 2018 24rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Stockholm, Sweden (2018.9.26-2018.9.28)] 2018 24rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Structural analysis and modelling of packaged light emitting devices by thermal transient measurements at multiple boundaries
摘要： The paper presents a comprehensive methodology for modeling the electrical, optical, and thermal domains of high-power LEDs, focusing on the XPE2 type from Cree. It introduces optimization algorithms (OPT1 and OPT2) to extract parameters such as series resistance (RS), ideality factor (m), and saturation current (I0) from forward voltage (VF) measurements. A quadratic model for radiant voltage (Vrad) is developed to describe the optical output, and thermal modeling is addressed through structure functions derived from transient thermal measurements. The approach enables accurate prediction of LED performance across varying currents and temperatures, with applications in thermal management and design optimization.
关键词： ideality factor,thermal management,structure function,LED modeling,radiant flux,forward voltage,saturation current,series resistance
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Reliability Physics Symposium (IRPS) - Burlingame, CA (2018.3.11-2018.3.15)] 2018 IEEE International Reliability Physics Symposium (IRPS) - High-temperature and high-field cycling reliability of PZT films embedded within 130 nm CMOS
摘要： We present a systematic reliability study of PZT polarization retention after exposure to high temperatures and high-field cycling. After a 260 °C Pb-free solder assembly reflow-like exposure, a signal margin of >10 μC/cm2 is achieved at a read voltage of 1 V. Extraction of the Preisach distribution after thermal depolarization and restore exhibits an increase in the positive coercive voltage by 45 % while the negative coercive voltage shows minimal deviation (<7 %). Under accelerated aging via high electric fields (2.4 V), maximum wake-up at 106 cycles followed by fatigue >108 cycles is observed. Asymmetry in coercive voltage is minimized after wakeup and remanent polarization maximized. After fatigue, a signal margin >10 μC/cm2 is maintained for read voltages >0.8 V.
关键词： high-temperature bake,Ferroelectric capacitor,thermal depolarization,cycling,data retention,imprint
更新于2025-09-23 15:23:52
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Achieving high-resolution thermal imagery in low-contrast lake surface waters by aerial remote sensing and image registration
摘要： A two-platform measurement system for realizing airborne thermography of the Lake Surface Water Temperature (LSWT) with ~0.8 m pixel resolution (sub-pixel satellite scale) is presented. It consists of a tethered Balloon Launched Imaging and Monitoring Platform (BLIMP) that records LSWT images and an autonomously operating catamaran (called ZiviCat) that measures in situ surface/near surface temperatures within the image area, thus permitting simultaneous ground-truthing of the BLIMP data. The BLIMP was equipped with an uncooled InfraRed (IR) camera. The ZiviCat was designed to measure along predefined trajectories on a lake. Since LSWT spatial variability in each image is expected to be low, a poor estimation of the common spatial and temporal noise of the IR camera (nonuniformity and shutter-based drift, respectively) leads to errors in the thermal maps obtained. Nonuniformity was corrected by applying a pixelwise two-point linear correction method based on laboratory experiments. A Probability Density Function (PDF) matching in regions of overlap between sequential images was used for the drift correction. A feature matching-based algorithm, combining blob and region detectors, was implemented to create composite thermal images, and a mean value of the overlapped images at each location was considered as a representative value of that pixel in the final map. The results indicate that a high overlapping field of view (~95%) is essential for image fusion and noise reduction over such low-contrast scenes. The in situ temperatures measured by the ZiviCat were then used for the radiometric calibration. This resulted in the generation of LSWT maps at sub-pixel satellite scale resolution that revealed spatial LSWT variability, organized in narrow streaks hundreds of meters long and coherent patches of different size, with unprecedented detail.
关键词： Lake surface water temperature,Uncooled infrared camera,Image registration,Lake Geneva,Thermal imagery,Aerial remote sensing
更新于2025-09-23 15:23:52
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[IEEE 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD) - Yassmine Hammamet, Tunisia (2018.3.19-2018.3.22)] 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD) - An Integrated Thermal and Electrical Model for PV Panel Performance
摘要： This work presents an integrated thermal and electrical model for Photovoltaic panel based on Matlab/Simulink tools. The model is designed for extreme and dusty weather conditions. The objective of this work is to reach a realistic online simulation that accommodates all major environmental variables such ambient temperature, relative humidity, wind speed and solar irradiation. The water mass flow rate was used to control the PV panel temperature through surface cooling in order to boost its output power. The output power adjustment was needed for power system operation purposes. The developed model is now ready any future controller development. The obtained results for testing the model under varying online climatic conditions and for various water mass flow rates were very satisfactory. The use of water to cool the panel played two major roles namely PV cleaning and temperature reduction then consequently increasing the panel power output.
关键词： Thermal model,Simulation,surface cooling,PV panel performance,Electrical model
更新于2025-09-23 15:23:52
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Thermal Analysis of AlGaN/GaN High-Electron-Mobility Transistors with Graphene
摘要： A thermal analysis of AlGaN/GaN high electron mobility transistors (HEMTs) with Graphene is investigated using Silvaco and Finite Element Method. Two thermal management solutions are adopted; first of all, graphene is used as dissipation material between SiC substrate and GaN buffer layer to reduce thermal boundary resistance of the device. At the same time, graphene is also used as a thermal spread material on the top of the source contacts to reduce thermal resistance of the device. The thermal analysis results show that the temperature rise of device adopting graphene decreases by 46.5% in transistors operating at 13.86 W/mm. Meanwhile, the thermal resistance of GaN HEMTs with graphene is 6.8 K/W, which is much lower than the device without graphene, which is 18.5 K/W. The thermal management solutions are useful for integration of large-scale graphene into practical devices for effective heat spreading in AlGaN/GaN HEMT.
关键词： AlGaN/GaN,Thermal Management,High-Electron-Mobility Transistors (HEMTs),Graphene
更新于2025-09-23 15:23:52
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Effect of laser forming on mechanical properties of multiple-phase steels by using a thermal–microstructure–mechanical model
摘要： Based on a forming temperature-controlled mixed strain-hardening law, a temperature-controlled thermal–microstructure–mechanical model was developed to predict the deformation in ferrite–martensite dual-phase steel before and after complex laser forming. Phase transformation in dual phase steel was predicted by coupling a kinetic transformation model with the developed model during laser forming. The corresponding algorithm of the constitutive model was used in three-dimensional finite element method to simulate the material deformation and mechanical properties during the laser forming. The simulated results agree well with the experimental results. Laser forming influences the mechanical properties of the material significantly, leads to bending deformation of the scanned sample and induces a ferrite-to-martensite transformation. The influence of scanning line number on the tensile strength and bending deformation of the scanned specimen was investigated. The tensile strength and bending angle are related positively to the number of scanning lines on the sample.
关键词： Stress-strain curve,Phase transformation,Thermal–microstructure–mechanical model,Sheet metal,Laser forming
更新于2025-09-23 15:23:52
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Thermal Deformation Analysis and Electron Beam Optics Simulation for a Thermionic Electron Gun Design
摘要： When the thermionic electron gun of the klystron operates, the structure around the cathode is subjected to thermal deformation due to the high operating temperature of the cathode. A thermal deformation analysis of the existing electron gun with 'cold' dimensions (dimension on fabrication) was done using the ANSYS code to get the 'hot' dimensions of the electron gun on operation. After that, the optics of the emitted electron beam were simulated using two codes (EGUN and CST-PS) for the two cases of the 'cold' dimension and the 'hot' dimension. We compared the beam trajectories of the above two cases to investigate the change in the physical quantities, which would have a strong effect on the klystron performance due to the thermal deformation. The thermal deformation was found to cause a perveance change as large as 15%. The scalloping behavior was also investigated with an applied magnetic field for the two cases of cold and hot dimensions.
关键词： EGUN code,CST code,Electron gun,ANSYS code,Klystron,Thermal deformation
更新于2025-09-23 15:23:52