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Modeling of laser heating of bi-layered microdomain using the general boundary element method
摘要： Heat transfer processes occurring in 3D bi-layered microdomain subjected to the ultra-short laser pulse are considered. The problem is described by the system of two dual-phase lag equations supplemented by appropriate boundary and initial conditions. The ideal contact condition at the interface between the layers in the case of the dual-phase lag model is formulated in a di?erent way than in the macroscopic Fourier one. To solve the problem the general boundary element method is proposed. In the ?nal part of the paper the examples of computations are presented, and the conclusions are formulated.
关键词： Microscale heat transfer,Dual-phase lag model,Laser heating,General boundary element method
更新于2025-09-16 10:30:52
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Selective oxidation of the surface layer of bilayer WSe <sub/>2</sub> by laser heating
摘要： WSe2 films have several anisotropies between the in-plane and out-of-plane directions, which affects their responses to external operation. Guided by the anisotropies, we provide adequate heat propagation to oxidize selectively the surface layer of bilayer WSe2 and characterized the structure of monolayer WSe2 covered with an oxidized layer by optical and atomic force microscopy, Raman spectroscopy and photoluminescence measurements. Furthermore, we found indications that laser treatments of monolayer WSe2 covered with an oxidized layer have possibility to cause photoactivated oxidation. Our observations suggest clues to understand low-dimensional oxidation behaviours.
关键词： anisotropy,laser heating,WSe2,selective oxidation,photoluminescence
更新于2025-09-12 10:27:22
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[IEEE 2019 3rd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT) - Ankara, Turkey (2019.10.11-2019.10.13)] 2019 3rd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT) - Manufacturing Graphene via Laser Heating
摘要： This study focuses on the investigation of an alternative method for graphene production. There are various ways of manufacturing graphene sheets. Each method has it is own advantages and disadvantages. However, the common problem is about the cost and time associated with these particular routes. In this study, we have developed an alternative mechanism that utilizes laser beam as heating source to help thermal decomposition of silicon carbide in order to obtain graphene sheets. The manufactured samples were compared with graphene sheets that were prepared with traditional thermal decomposition method using a high temperature furnace. The results showed that the alternative way of manufacturing has promise for graphene formation since Raman spectrum showed graphene peaks in corresponding locations with satisfactory shapes. This could lead to potentially single layer graphene on a large scale after optimizing the manufacturing setup and, consequently, could either reduce the fabrication costs or reduce the time required for epitaxial growth process. Few rearrangements such as laser power, flow rate of the gas or pressurizing the chamber could make the process an applicable approach.
关键词： epitaxial growth,laser-heating,thermal decomposition,graphene
更新于2025-09-12 10:27:22
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Comparison between multi-frequency and multi-speed laser lock-in thermography methods for the evaluation of crack depths in metal
摘要： Two original methods using lock-in thermography with a laser excitation are proposed for the estimation without contact of open crack depths in metal. The first uses a modulated punctual thermal source and is well suited for the study of complicated structures. In the second, a continuous moving thermal source allows to scan homogeneous structures. Each method relies on the heat diffusion modifications induced by a crack located in the thermal diffusion area of the synchronised heat source. The thermal signature of the crack is extracted to the amplitude of surface temperature images for various modulation frequencies or various scanning speeds of the thermal source. The thermal signatures are analysed according to a length representative of the thermal diffusion length to give a local evaluation of the crack depth. The obtained results demonstrate the potentiality of active lock-in thermography as a contactless measurement tool for the evaluation of crack depths up to 3 mm.
关键词： Infrared thermography,crack sizing,non-destructive testing,laser heating,crack depth,lock-in thermography
更新于2025-09-12 10:27:22
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Parabolic two-step model and accurate numerical scheme for nanoscale heat conduction induced by ultrashort-pulsed laser heating
摘要： Simulation of nanoscale heat transfer phenomena has attracted great attention, particularly the nano-scale heat conduction induced by ultrashort-pulsed laser heating. In this article, we propose a nanoscale parabolic two-step model and an accurate numerical scheme for thermal analysis of the nanoscale heat conduction induced by ultrashort-pulsed laser heating. To this end, we first introduce the Knudsen number (Kn) into the original parabolic two-step heat conduction equations and couple them with the Kn-dependent and temperature-jump boundary condition. We then develop a fourth-order accurate compact finite difference method for solving the nanoscale model. Stability and convergence of the obtained numerical scheme are analyzed theoretically. We finally test the accuracy and applicability of the nanoscale model and the obtained numerical scheme in three examples. By choosing various values of the Kn and the parameter α in the boundary condition, the simulation could be a tool for analyzing the nanoscale heat conduction induced by ultrashort-pulsed laser heating.
关键词： Nanoscale heat conduction,Convergence,Compact finite difference scheme,Stability,Ultrashort-pulsed laser heating
更新于2025-09-12 10:27:22
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Transformation of the dermal collagen framework under laser heating
摘要： The aim of this study was to compare between the changes undergone by the framework when dermal collagen heated by IR laser radiation and by traditional means and to reveal the specific features of the dermal matrix modification under moderate IR laser irradiation. Rabbit skin specimens were heated to 50°C, 55°C, 60°C and 65°C in a calorimeter furnace and with a 1.68-μm fiber Raman laser. The proportion of the degraded collagen macromolecules was determined by differential scanning calorimetry. Changes in the architectonics of the collagen framework were revealed by using standard, phase-contrast, polarization optical and scanning electron microscopy techniques. The collagen denaturation and dermal matrix amorphization temperature in the case of laser heating proved to be lower by 10°C than that for heating in the calorimeter furnace. The IR laser treatment of the skin was found to cause a specific low-temperature (45°C-50°C) transformation of its collagen framework, with some collagen macromolecules remaining intact. The transformation reduces to the splitting of collagen bundles and distortion of the course of collagen fibers. The denaturation of collagen macromolecules in the case of traditional heating takes its course in a threshold manner, so that their pre-denaturation morphological changes are insignificant.
关键词： calorimetry,collagen transformation,skin,laser heating
更新于2025-09-11 14:15:04
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Investigation of Polymer Matrix Nano‐Aluminum Composites with Pulsed Laser Heating by In‐Situ TEM
摘要： Nanocomposites of aluminum and fluoropolymers react rapidly due to highly exothermic aluminum fluorination because of the high specific surface area nanoscale particles. In-situ transmission electron microscopy (TEM) techniques are invaluable for real time monitoring of the reactions in these systems at the nanoscale. Here, we investigated the reactions in nanoscale Al (nAl) and THV (terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride) and nAl-LDPE (low density polyethylene) composites, heated using a pulsed laser in a TEM. Results show that reactions are initiated at about 720 K, when THV starts to decompose, and proceed with the formation and growth of a hollow aluminum fluoride (AlF3) shell. Diffraction patterns revealed that this phase is the rare η-phase AlF3. In contrast, no reactions were observed in the inert nAl-LDPE composites. The experimental and theoretical results reveal that rapid pulsed laser heating and subsequent cooling of a nanoscale sample influences the phases that can form, and can be utilized to investigate other systems.
关键词： Fluoropolymer,Nanoenergetic composites,Laser Heating,In situ TEM
更新于2025-09-11 14:15:04
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Infrared Thermography and DIT of Quadcopter Rotor Blades Using Laser Heating
摘要： A measuring method to detect wall flow topologies by active infrared thermography was developed. Quadcopter rotor blades were studied in typical hover and forward flight conditions, while using a high-power infrared laser to heat the blade surface. By this, the distance between heat source and measuring object could be significantly increased compared to conventional heat sources. The resulting images show little blurring at high signal-to-noise ratios. In steady-state flow conditions, wall flow topologies could be detected reliably and show good agreement with performed oil-film interferometry measurements. Wind tunnel experiments at forward flight conditions were conducted and indicate unsteady shifts of the transition location.
关键词： laser heating,rotor blades,differential infrared thermography,boundary-layer transition,thermography,oil-film interferometry
更新于2025-09-11 14:15:04