- 标题
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Transition regime in the ultrafast laser heating of solids
摘要： Based on the phenomenological theory of heat diffusion, we show that the generated peak temperature Tmax after absorption of a laser pulse strongly depends on the pulse duration. We identify three different heat conduction regimes that can be identified via a simple parameter that depends only on the pulse duration and on material constants. The phenomenological approach is supported by numerical simulations of heat diffusion and measurements of the thermal surface expansion after transient grating excitation with 1 ps and 10 ns optical pulses.
关键词： laser heating,heat diffusion,thermal surface expansion,pulse duration
更新于2025-09-23 15:19:57
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Cesium Lead Bromide Quantum Dot Light-Emitting Field-Effect Transistors
摘要： Solution processible perovskite quantum dots are considered as promising optical materials for light emitting optoelectronics. The light-emitting field-effect transistors that can be operated under relatively lower potential with an efficient energy conversion efficiency have yet to be realized with the perovskite quantum dot. Here, we present the CsPbBr3 quantum dot-based light-emitting field-effect transistor (LEFET). Surprisingly, unipolar transport characteristics with strong electroluminescence was observed at the interface of the CsPbBr3 QD-LEFET along with the exceptionally wide recombination zone of 80 μm, an order of magnitude larger than that of organic/polymer light-emitting field-effect transistors. Based on the systematic analysis for the electroluminescence of the CsPbBr3 NC-LEFET, we revealed that the increased diffusion length determined by the majority carrier mobility and the lifetime well explains the remarkably wide recombination zone. Furthermore, it was found that the energy-level matching and transport geometry of the hetero-structure also determine the charge distribution and recombination, substantially affecting the performance of the CsPbBr3 QD LEFET.
关键词： Organic/inorganic hybrid field-effect-transistor,Light emitting field-effect-transistor,Wide recombination zone,Diffusion length,CsPbBr3 quantum dots
更新于2025-09-23 15:19:57
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CRDS modelling of deuterium release from co-deposited beryllium layers in temperature programmed and laser induced desorption experiments
摘要： Deuterium release from Be/D layers co-deposited using high power impulse magnetron sputtering (HiPIMS) is modelled with rate equations using the CRDS code under conditions of temperature programmed (TPD) and laser induced (LID) Desorption experiments. TPD results are simulated to fit D trapping parameters that are in turn applied to simulate the LID. TPD results are compared to equivalent results from JET-ILW and UCSD samples. HiPIMS samples show a different release behavior compared to UCSD and JET samples, release peaks at comparable heating rates are narrower and cannot be modelled using the same set of parameters. With a particular choice of diffusion-trapping parameters that reproduce the TPD peak positions, modelling of the LID efficiency results in a qualitative agreement with experimental observations. In particular, it is shown that a complete outgassing of low D content samples is not possible during laser heating unless the surface temperature exceeds the Be melting threshold.
关键词： beryllium co-deposits,hydrogen retention,reaction–diffusion,TPD,CRDS,LID
更新于2025-09-23 15:19:57
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[IEEE 2019 21st International Middle East Power Systems Conference (MEPCON) - Cairo, Egypt (2019.12.17-2019.12.19)] 2019 21st International Middle East Power Systems Conference (MEPCON) - Technical Overview of Connecting Small Scale Photovoltaic Systems in Egypt
摘要： Information diffusion in social networks is often characterized by huge participating communities and viral cascades of high dynamicity. To observe, summarize, and understand the evolution of dynamic diffusion processes in an informative and insightful way is a challenge of high practical value. However, few existing studies aim to summarize networks for interesting dynamic patterns. Dynamic networks raise new challenges not found in static settings, including time sensitivity, online interestingness evaluation, and summary traceability, which render existing techniques inadequate. We propose dynamic network summarization to summarize dynamic networks with millions of nodes by only capturing the few most interesting nodes or edges over time. Based on the concepts of diffusion radius and scope, we define interestingness measures for dynamic networks, and we propose OSNet, an online summarization framework for dynamic networks. Efficient algorithms are included in OSNet. We report on extensive experiments with both synthetic and real-life data. The study offers insight into the effectiveness, efficiency, and design properties of OSNet.
关键词： interestingness,graph mining,Dynamic networks,graph summarization,diffusion process,network cascades
更新于2025-09-23 15:19:57
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Scaled conductance quantization unravels the switching mechanism in organic ternary resistive memories
摘要： Organic ternary resistive random access memories (RRAMs) can dramatically increase information density, but the effective device yield remains too low for practical applications. Further improvements are inefficient as the switching mechanism is poorly understood. Here, we demonstrate for the first time that quantized conduction occurs and is involved in the switching mechanism of organic ternary RRAMs. The conductance values in organic ternary RRAMs are quantified in units of the quantum conductance G0 but scaled by a factor b, in contrast to that of inorganic RRAMs without scaling. In situ elemental mapping reveals that evaporated Al diffuses into organic layers and causes the formation of quantum channels. The organic materials act as diodes to regulate the external voltage and contribute to b { 1. A roughly positive correlation between the scale factor b and ternary device yield was found, which might provide a new way to improve the ternary device yield and will stimulate more material innovation for organic ternary RRAMs.
关键词： switching mechanism,organic ternary resistive random access memories,quantum conductance,quantized conduction,Al diffusion
更新于2025-09-23 15:19:57
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The influence of phosphor particles on the water transport in optical silicones for LEDs
摘要： The reliability of LEDs decreases in moist environments. One potential gateway of moisture ingress, reducing the product lifetime is the lens. In white LEDs, phosphor particles are embedded into the optical silicone of the lens to convert the blue light emitted by the diode down in frequency and achieve a light output that appears white. In this study, the influence of these phosphor particles on the moisture sorption, permeation and diffusion in optical silicones is investigated by comparing two silicone resins that are commonly used in LEDs, both with and without the addition of phosphor particles. The results of two methods are compared: the wet-cup method and a gravimetric approach of dynamic vapour sorption (DVS). Diffusion coefficients between 20 and 75 C are reported as well as sorption isotherms, activation energy and sorption enthalpy. It is concluded that the addition of phosphor particles only has a very small impact on the moisture transport properties of the silicones.
关键词： Diffusion,Dynamic vapour sorption (DVS),Moisture transport,Phosphor particles,Silicone,LED
更新于2025-09-23 15:19:57
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Impact of laser treatment on hydrogenated amorphous silicon properties
摘要： The application of laser radiation to locally modify the hydrogen distribution within hydrogenated amorphous silicon films on a short time scale is studied. The impact of laser power and irradiation time on the temperature of the silicon layer during the laser treatment and the hydrogen outdiffusion is analyzed. Moreover, the resulting optoelectronic properties of the amorphous silicon are examined. On a timescale of a few seconds or less, we can successfully decrease the hydrogen concentration in the surface-near region of the silicon layer without major impact on the optoelectronic properties.
关键词： laser treatment,amorphous silicon,hydrogen diffusion
更新于2025-09-23 15:19:57
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Mapping of Bulk Diffusion Length and Effective Back Surface Recombination Velocity in Silicon Solar Cells
摘要： Mapping of diffusion length (L) in the bulk region and effective back surface recombination velocity (SRV) in Al-BSF and PERC Si solar cells has been carried out by utilizing the spectral response (SR) at desired wavelengths. Light beam induced current (LBIC) technique was used to generate the maps of SR and re?ectivity (R) on cell area (6”x6”). MATLAB tool was used to convert the spatial maps of SR and R into L and SRV. We found that (i) the distribution of L in multi-crystalline cells varied from grain to grain in wide range (150-600 μm) while in mono-crystalline cells, it varied in rather narrow range (450-600 μm) ; (ii) the values of SRV for PERC cells (120-250 cm/sec for mono-crystalline and 100-250 cm/sec for multi-crystalline) and Al-BSF cells (320-400 cm/sec for mono-crystalline and 250-350 cm/sec for multi-crystalline) differ by considerable magnitude due to passivation quality at back side. Three multi-crystalline Al-BSF Si solar cells of cell ef?ciencies 17.6%, 17.9% and 18.1% were investigated with the proposed methodology and demonstrated that the ef?ciency de?cit is primarily due to defects present in bulk material and poor back surface passivation.
关键词： Light beam induced current,Surface recombination velocity,Diffusion length,Si solar cells
更新于2025-09-23 15:19:57
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Gas-vapor Interplay in Plasmonic Bubble Shrinkage
摘要： The understanding of the shrinkage dynamics of plasmonic bubbles formed around metallic nanoparticles immersed in liquid and irradiated by a resonant light source is crucial for the usage of these bubbles in numerous applications. In this paper we experimentally show and theoretically explain that a plasmonic bubble during its shrinkage undergoes two different phases: first, a rapid partial bubble shrinkage governed by vapor condensation and, second, a slow diffusion-controlled bubble dissolution. The history of the bubble formation plays an important role in the shrinkage dynamics during the first phase, as it determines the gas-vapor ratio in the bubble composition. Higher laser powers lead to more vaporous bubbles, while longer pulses and higher dissolved air concentrations lead to more gaseous bubbles. The dynamics of the second phase barely depends on the history of bubble formation, i.e. laser power and pulse duration, but strongly on the dissolved air concentration, which defines the concentration gradient at the bubble interface. Finally, for the bubble dissolution in the second phase, with decreasing dissolved air concentration, we observe a gradual transition from a R(t) ∝ (t0 ? t)1/3 scaling law to a R(t) ∝ (t0 ? t)1/2 scaling law, where t0 is the lifetime of the bubble and theoretically explain this transition.
关键词： dissolved air concentration,laser power,pulse duration,plasmonic bubbles,vapor condensation,shrinkage dynamics,diffusion-controlled dissolution
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Communication and Electronics Systems (ICCES) - Coimbatore, India (2019.7.17-2019.7.19)] 2019 International Conference on Communication and Electronics Systems (ICCES) - Modeling and Simulation of gird connected hybrid power system integrated with solar PV/Wind and controlled by Voltage Regulator
摘要： Existing studies have contributed immensely to link prediction by identifying different types of network communities. In this paper, a new type of network community in online social networks (OSNs) is identified using the association between network nodes. This new network community is called ‘‘virtual community.’’ Virtual communities are based on either the real/ physical relationships of users that are connected to their constituency, social, and professional activities or their virtual interactions associated with their cognitive levels, choice selection, and ideology. Users belonging to the same virtual community exhibit similar behavior in linking to nodes of common interest. These nodes, which reflect the common interest of a community, are called ‘‘prime nodes.’’ Prime nodes are linked to the prediction problem in OSN completion and are generally recommended for OSN growth. Recent studies on ranking algorithms have shown that the incompleteness of OSNs contributes to the low accuracy of ranking algorithms in identifying top spreaders. Thus, in this paper, we propose an OSN completion method based on link prediction through association between prime nodes. An experiment on predicting new links in two real big data sets of two global OSNs, namely, Facebook and Twitter, is conducted. The effectiveness of the proposed method is also validated by applying prominent ranking algorithms to the newly predicted and original networks. Results show that the accuracy rates of the ranking algorithms are improved, thereby validating the importance of the proposed method in predicting vital links.
关键词： virtual community,Information diffusion,ranking algorithm,link prediction,network community,online social network,prime node
更新于2025-09-23 15:19:57