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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Modelling Charge Generation and Transport in Low Density Polyethylene Irradiated by an Electron-Beam
摘要： One way to bypass charge generation due to injection in an insulator sandwiched between parallel electrodes and submitted to an applied voltage is to implant charges in the material with the help of an electron beam. The electrons position and quantity is theoretically known as long as the beam energy and beam current are known. Low density polyethylene (LDPE) has been characterized with in-situ space charge measurements by pulsed electroacoustic method during irradiation, and with ex-situ measurements while a DC voltage is applied. A fluid charge transport model has been developed using a commercial software, to reproduce the space charge behaviour during and after irradiation. Simulated results during irradiation are first compared to in-situ space charge measurements, in order to validate the model parameters related to e-beam irradiation. Simulations are then performed on post-irradiated samples, polarized under different electric fields. Space charge measurements and current measurements are available for comparison. Simulated results are in relatively good agreement with experimental ones as long as the model parameters are adapted to irradiated low density polyethylene, compared to a best set of parameters adapted uniquely for non-irradiated polyethylene.
关键词： charge generation and transport,fluid model,LDPE,ageing,electron-beam irradiation
更新于2025-09-23 15:22:29
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Predicting Mechanical Strength of In-Use Firefighter Protective Clothing Using Near-Infrared Spectroscopy
摘要： The exact lifespan of in-use firefighter protective clothing is difficult to predict due to the large variations in use between individual garments. Furthermore, testing methods used to evaluate new protective clothing are destructive in nature and could not be applied to in-use garments. Various non-destructive techniques have been proposed for the evaluation of in-use clothing, each possessing its own advantages and disadvantages. The ability of near-infrared spectroscopy to predict the tensile strength of thermally aged fabrics used in protective clothing for wildland firefighters and other workers is investigated here. Fabrics were exposed to heat fluxes from 10 kW/m2 to 40 kW/m2 for various durations using the cone calorimeter, after which the tensile strength of the fabrics was measured. Temperatures measured during the exposures and results of thermal gravimetric analysis tests were used to interpret changes in tensile strength. Multivariate linear regression was used to develop correlations between the tensile strength and the reflectance values measured between 1500 nm and 2500 nm for new and thermally aged fabrics. It was found that models based on reflectance measurements made at as few as three wavelengths could be used to estimate the tensile strength of the thermally aged specimens.
关键词： Thermal ageing,Near-infrared spectroscopy,Firefighter,Durability,Non-destructive testing,Protective clothing
更新于2025-09-23 15:22:29
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Dynamics of Instability in Plasmonic Response of Nanostructured Gold Thin Films on Ambient Ageing
摘要： Instability in the plasmonic response of nanostructured gold (Au) thin films on ambient ageing has been investigated. Different types of Au nanostructures (island, percolated, and continuous thin film) are obtained at the early stage of thin film growth by variation in film thickness using sputtering technique. Absorbance spectra of as-deposited island Au film shows a systematic blue-shift in the localized surface plasmon resonance (LSPR) peak position on ageing. The rate of blue-shift in the LSPR peak position is fitted with single-exponential decay function to analyze the dynamics of the plasmonic response. The as-deposited percolated Au film displays a transformation of broadened plasmonic response into a wavelength independent absorbance profile on ageing. The immersion of a new plasmonic band in the absorbance spectra is noted for continuous Au thin film on ageing. The change in plasmonic responses of nanostructured Au thin films on ambient ageing is found to be directly correlated with the re-organization of the surface morphology. Finally, ageing-induced solid-state dewetting and crystallization are found to be the main responsible processes of the underlying mechanism for morphological re-organizations, leading to change in the plasmonic response of the nanostructured Au thin films.
关键词： X-ray reflectivity,Grazing incidence X-ray diffraction,Localized surface plasmon resonance,Thin film ageing,Transmission electron microscopy
更新于2025-09-23 15:19:57
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Properties of Laser Metal Fused AlSi10Mg Alloy Processed Using Different Heat Treatments; Eigenschaften einer lasergeschmolzenen AlSi10Mg-Legierung und Anwendung von verschiedenen W?¤rmebehandlungen;
摘要： The AlSi10Mg alloy was fabricated by Laser Metal Fusion (LMF) using different post processing conditions. Tensile and dilatometric specimens were obtained with longitudinal axis parallel to the building direction. A first set of samples was directly aged in the as-built state (AB), while a second batch underwent solubilization annealing (SA) at 540 °C for 60 min just before artificial ageing (AA) at 160 °C for 8 h. Solubilization caused the precipitation of Si particles, suppressed by the rapid solidification during SLM. Moreover, it caused partial recrystallization leading to a coarser microstructure. The ageing response was very different in the two cases, involving a higher starting hardness for the as-built material, showing a markedly higher hardness during the whole process. In the as-built material, isochronal ageing experiments carried out by differential scanning calorimetry showed the precipitation of Mg2Si particles beneath Si, while the same transformations were much less intense in the solubilized sample, due to the lower Si supersaturation. The ageing process raised the yield strength of about 20% compared to the AB material, slightly reducing the fracture elongation. The same alloy after SA+AA showed a strength 25% lower than the AB+AA material, while ductility significantly increased.
关键词： Solution annealing,Ageing,AlSi10Mg,Laser Metal Fusion
更新于2025-09-23 15:19:57
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Nanostructured Al0.2Y1.8O3 Semiconductor Assisted Enhancement in PVOH Fortitude to
摘要： An appreciable enhancement in UV endurance of poly(vinyl alcohol) (PVOH) films has been achieved by using nanostructured Al0.2Y1.8O3 semiconductors. The effect of shorter wavelength UV radiations on physico-mechanical and opto-electronic behaviors were established by surface morphological, optical and mechanical characterizations. While, the enhancement in photo stabilities of PVOH/Al0.2Y1.8O3 nanocomposite films were accessed via optical and mechanical studies. The optical transmittance, fluorescence emission, tensile behaviors and contact angle behaviors of PVOH/Al0.2Y1.8O3 film remain almost unaltered upon UV irradiation, while there occurred detrimental changes in physico-mechanical and optical behaviors of pristine PVOH upon UV curing. The anti UV-ageing property of Al0.2Y1.8O3 reinforced PVOH NCs was achieved through deactivation of UV induced photo-oxidative deterioration through Al0.2Y1.8O3 nanofiller assisted energy drain in conjunction with photonic down conversion.
关键词： nanocomposites,PVOH,UV-ageing,photo-oxidation,photo-excitation
更新于2025-09-19 17:15:36
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Analysis on FM-to-AM conversion of SSD beam induced by etalon effect in a high-power laser system
摘要： Malondialdehyde (MDA) was selected to represent a secondary by-product of lipid peroxidation during rice ageing. This study aimed to investigate the effects of MDA modification on the structural characteristics of rice protein. The results showed that as MDA concentration increased, rice protein carbonyl and disulphide groups increased, but sulphydryl content decreased. The blue shift of maximum fluorescence peak, the decrease of rice protein intrinsic fluorescence intensity and the reduction of surface hydrophobicity indicated the formation of protein aggregates caused by MDA oxidative modification. The results of molecular weight distribution and particle size distribution showed that MDA modification resulted in the formation of soluble protein aggregates, and the decrease of rice protein solubility indicated that insoluble protein aggregates were formed. Results of protein electrophoresis showed that MDA modification contributed to rice protein aggregation via non-disulphide covalent bonds. The results showed that rice protein gradually aggregated with increasing MDA concentration.
关键词： Aggregation,rice protein,protein oxidation,lipid peroxidation,rice ageing,malondialdehyde
更新于2025-09-19 17:13:59
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[OSA Optical Fiber Sensors - Lausanne (2018..-..)] 26th International Conference on Optical Fiber Sensors - Accelerated Through-Life Performance Evaluation of Fibre Fabry-Pérot Pressure Sensors
摘要： Fibre Fabry-P′erot pressure sensors were evaluated for use in long-term experiments. Sensors were pressure cycled in excess of 7000 times over a 51 week duration. No ageing effects were discernible throughout this period.
关键词： pressure sensors,ageing effects,long-term experiments,Fibre Fabry-P′erot
更新于2025-09-16 10:30:52
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Elaboration of microporous CeO2 thin layers having nanocrystallites network controlled by Pluronic P123: Impact of key experimental parameters
摘要： Microporous ceria thin ?lms having nanocrystallites network were synthesized by evaporation-induced self-assembly process, using P123 amphiphilic copolymer as structure-directing agent. The impact of key experimental parameters, i.e., the sol ageing, the relative humidity (RH), the thermal treatment, on the thin layer elaboration were investigated. The results show that the organization of the nanoparticles is possible for a sol ageing time lower than 16 days and that the size of the mesophase within the thin layer increases with the relative humidity ?xed during the ?lm deposition. Finally, an increase of the thermal treatment temperature from 300 to 1000 °C leads to the formation of ?uorite-like dioxide material coupled with a loss of nanocrystallites organization and porosity due to the increase of the size of the crystallites. This loss of nanocrystallites organization is more drastic in the direction perpendicular to the surface and less pronounced along the surface. Thus, a compromise between the crystallization and the preservation of the porosity needs to be found.
关键词： relative humidity,P123 amphiphilic copolymer,evaporation-induced self-assembly,nanocrystallites network,thin films,thermal treatment,Microporous ceria,sol ageing
更新于2025-09-16 10:30:52
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Nondestructive monitoring of damage caused by accelerated ageing in photovoltaic modules
摘要： Accelerated ageing tests of photovoltaic laminates are requested by the IEC standards for quality control, which require the assessment of the electrical power losses after a prescribed amount of temperature and/or humidity cycles inside a climatic chamber (thermal cycling, humidity freeze, and damp heat tests). Since electric damage is measured only at the end of such tests, its kinetics induced by thermo-elastic stresses and the related degradation phenomena are reported in few cases. The aim of this study is to investigate the progress of damage, reporting the results of an unprecedented experimental campaign on a photovoltaic mini-module composed of nine multi-crystalline silicon solar cells, one of them containing a cracked cell, subject to a revised thermal cycling test including moisture. Every 40 cycles, and up to 460 (corresponding to 1840 h of testing), the progress of electric damage is assessed by monitoring the evolution of the overall electric resistance of the module. Moreover, electroluminescence images are taken with the same time interval, to assess local damage phenomena responsible for electric power-losses. Cracks are found to significantly accelerate the progress of damage as compared to what happens in intact solar cells, inducing progressive gridline failure and the spread of electrically inactive zones.
关键词： thermo-mechanical stresses,electroluminescence,accelerated ageing tests,Photovoltaics,nondestructive monitoring
更新于2025-09-12 10:27:22
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Evaluation of penetration process into young and elderly skin using confocal Raman spectroscopy
摘要： Non-invasive in vivo human studies have always been of great importance owing to their advantages over the invasive studies. This research work also presents such a non-invasive study dealing with the penetration of two vitamin derivatives: retinyl acetate and alpha-tocopheryl acetate, into the stratum corneum of two groups of study participants categorized based on age as young (average age of 24.1 ± 3.3 years old) and elderly groups (average age of 68 ± 5.8 years old). According to the increase of age it is expected that intrinsic alterations may occur in the stratum corneum. Understanding these alterations is relevant to the knowledge of the differences between stratum corneum as a function of age-dependence thus, leading to the development of new specific products for ageing. The penetration of these derivatives was semi-quantitatively analyzed using confocal Raman spectroscopic technique with 3510 Skin Composition Analyzer (River Diagnostics, Rotterdam, The Netherlands) with a diode laser of 785 nm wavelength and 26 mW power. The analysis was done in the extended fingerprint region (1800 - 400 cm-1) for the stratum corneum region of the skin considering the depths from surface up to 24 μm. The results of this study clearly indicated that these two vitamin derivatives penetrated significantly into the stratum corneum of both study groups and their penetration was mainly affected by the composition of SC and their physico-chemical properties. The penetration profile of the alpha-tocopheryl acetate displays significant statistical difference (p < 0.05) between groups from surface up to 12 μm.
关键词： Non-invasive in vivo human skin study,Skin ageing,Vitamin penetration,Confocal Raman spectroscopy
更新于2025-09-10 09:29:36