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Uniform-in-time bounds for approximate solutions of the drift–diffusion system
摘要： In this paper, we consider a numerical approximation of the Van Roosbroeck’s drift–diffusion system given by a backward Euler in time and finite volume in space discretization, with Scharfetter–Gummel fluxes. We first propose a proof of existence of a solution to the scheme which does not require any assumption on the time step. The result relies on the application of a topological degree argument which is based on the positivity and on uniform-in-time upper bounds of the approximate densities. Secondly, we establish uniform-in-time lower bounds satisfied by the approximate densities. These uniform-in-time upper and lower bounds ensure the exponential decay of the scheme towards the thermal equilibrium as shown in Bessemoulin-Chatard (Numer Math 25(3):147–168, 2016).
关键词： Finite volume method,Uniform-in-time bounds,Scharfetter–Gummel scheme,Drift–diffusion system,Numerical analysis
更新于2025-09-23 15:23:52
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High frequency electromagnetic energy phenomena in chiral dielectric structures with distributed and localized conductive insertions
摘要： Chiral dielectric structures with conductive insertions have the tendency to peculiarly concentrate the electromagnetic energy, subject to their specific architecture. The study analyses the associated heating effect at high transmission levels at GHz frequency, for the applications related to electromagnetic shielding. The favorable shielding structure can suffer, in well defined situations, a mechanical stress and/or an acceleration of aging mechanisms.
关键词： Numerical analysis,Electrical properties,Honeycomb,Thermal analysis
更新于2025-09-23 15:22:29
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Numerical analysis of carrier-depletion InGaAsP optical modulator with lateral PN junction formed on III–V-on-insulator wafer
摘要： We numerically investigated the modulation characteristics of a carrier-depletion InGaAsP optical modulator with a lateral PN junction fabricated on a III–V-on-insulator (III–V-OI) wafer. Owing to the large electron-induced refractive index change in InGaAsP, the InGaAsP optical modulator with a doping concentration of 2 ' 1018 cm%3 in the PN junction exhibited a phase modulation e?ciency VπL of 0.17 Vcm, which was 6 times smaller than that of a Si modulator with the same structure. The doping concentration dependence revealed that αVπL, which is a product of the insertion loss α and VπL, can signi?cantly be improved using InGaAsP when the doping concentration was as high as 1 ' 1018 cm%3. Thus, we concluded that the phase modulation e?ciency and insertion loss can be improved simultaneously using InGaAsP instead of Si for a carrier-depletion optical modulator with a lateral PN junction.
关键词： InGaAsP,carrier-depletion,optical modulator,numerical analysis,III–V-on-insulator
更新于2025-09-23 15:21:21
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Adaptability analysis of radiative transport diffusion approximation in planar-graded-index media
摘要： To study the applicability of diffusion approximation method, the influence of the optical thickness, scattering albedo, and wall emissivity of the examined medium on the accuracy of the diffusion approximation is analyzed. The accuracy is determined by comparison with results obtained by using the Monte Carlo method. By calculating the dimensionless radiation heat flux distributions at the bottom of the medium for various parameter combinations, the influence of each optical parameter is analyzed. In addition, the adaptability of the diffusion approximation method to the case of a gradient-index medium is examined. The results show that in the homogeneous-refractive-index medium and the gradient-index medium, the accuracy of diffusion approximation method is improved by an increase in the optical thickness or the scattering albedo and by a decrease in the wall emissivity. Moreover, the maximum relative errors are primarily distributed at the medium boundary and center. In the case of increased optical thickness or decreased wall emissivity, the error of the diffusion approximation method becomes stable and remains at a small value.
关键词： numerical analysis,relative error,diffusion approximation,gradient index,Radiative transfer
更新于2025-09-23 15:21:21
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Impact of Nonlinear Kerr Effect on the Focusing Performance of Optical Lens with High-Intensity Laser Incidence
摘要： The rapid development of high-energy and high-power laser technology provides an important experimental means for the research of extreme physical state in the laboratory and for the design of large laser facilities for realizing inertial con?nement fusion. However, when the incident laser ?eld is very strong, the Kerr e?ect of materials a?ects the nominal performance of optical elements. In this work, the impact of Kerr e?ect on the focusing performance of an optical lens is studied by calculating and comparing the ?led patterns of focal spots for three di?erent incident laser beams together with three di?erent levels of light intensities. The traditional transfer function of an optical lens is ?rstly modi?ed according to the theory of nonlinear Kerr e?ect. We use the two-dimensional fast Fourier transform algorithm and angular spectrum algorithm to numerically calculate the ?eld distributions of focal spots in the nominal focal plane of lens and its adjacent planes based on the Fresnel di?raction integral formula. The obtained results show that the Kerr e?ect a?ects the focusing characteristics of lens, especially for the incidence of high-order Gaussian beams, such as Hermite-Gaussian beams and Laguerre-Gaussian beams. At the same time, the focal length and refractive index of lens also change the ?eld patterns of focal spots. The presented methodology is of great value in engineering applications where the practical problem with beam size up to 100 mm can be calculated using a common laptop computer. The work provides an e?cient numerical technique for high-intensity incident laser beams focused by lens that takes Kerr e?ect into consideration, which has potential applications in high energy density physics and large laser facilities for inertial con?nement fusion.
关键词： Kerr effect,optical lens,numerical analysis,focal spot,high-intensity laser
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE International Conference on Power, Electrical, and Electronics and Industrial Applications (PEEIACON) - Dhaka, Bangladesh (2019.11.29-2019.12.1)] 2019 IEEE International Conference on Power, Electrical, and Electronics and Industrial Applications (PEEIACON) - A Numerical Analysis of N-MoTe <sub/>2</sub> in Back Contact of CdTe Solar Cell
摘要： Thin-film PV cells with low-cost attractive materials are more appropriate over high-cost silicon-based solar cells as free renewable energy sources. Cadmium Telluride (CdTe) PV cells are widely investigated as one of the ultra-thin film PV cells. They have broadly researched to increase efficiency by improving different front contact and back contact material. the effect of unintentionally formed n-type Molybdenum Telluride (n-MoTe2) in the back contact interface between the Cadmium Telluride (CdTe) absorber layer and Mo layer has been investigated from a numerical analysis by the facilitation of AMPS-1D software. The variation of short circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF) and efficiency (η) are analyzed by changing four parameters like (i) layer thickness (ii) operating temperature (iii) donor concentration and (iv) sun intensity. From the numerical analysis a moderate performance is observed, where the efficiency of the solar cell is found about 16.532%, Jsc is 21.298 mAcm-2, Voc is 0.99 V and FF is 0.863 for the layer thickness, donor concentration, operating temperature and sun intensity at 60 nm, 1×1016cm-3, 350K, and 1.1 suns respectively.
关键词： numerical analysis,CdTe,Thin film PV cells,MoTe2
更新于2025-09-23 15:21:01
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Influence of Oxygen Vacancy Behaviors in Cooling Process on Semiconductor Gas Sensors: A Numerical Analysis
摘要： The in?uence of oxygen vacancy behaviors during a cooling process in semiconductor gas sensors is discussed by the numerical analysis method based on the gradient-distributed oxygen vacancy model. A diffusion equation is established to describe the behaviors of oxygen vacancies, which follows the effects of diffusion and exclusion in the cooling process. Numerical analysis is introduced to ?nd the accurate solutions of the diffusion equation. The solutions illustrate the oxygen vacancy distribution pro?les, which are dependent on the cooling rate as well as the temperature interval of the cooling process. The gas-sensing characteristics of reduced resistance and response are calculated. Both of them, together with oxygen vacancy distribution, show the grain size effects and the re-annealing effect. It is found that the properties of gas sensors can be controlled or adjusted by the designed cooling process. The proposed model provides a possibility for sensor characteristics simulations, which may be bene?cial for the design of gas sensors. A quantitative interpretation on the gas-sensing mechanism of semiconductors has been contributed.
关键词： numerical analysis,oxygen vacancy,gas sensor,semiconductor,diffusion equation
更新于2025-09-23 15:21:01
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Investigation of modulation transfer function in InGaAs photodetector small pitch array based on three-dimensional numerical analysis
摘要： Three-dimensional numerical simulation technology was used to investigate the influence of structural and material parameters on the modulation transfer function (MTF) of lattice matched InGaAs/InP planar small pitch arrays. We found that extending depletion zone through increasing depth of diffusion junction and reducing the doping concentration in the absorption layer plays a critical role in optimizing the MTF of arrays. And it is highly worth noting that the very optimization effects become even more pronounced in smaller pitch arrays, which offers valuable references to restrain crosstalk in highly dense array and strengthen the imaging ability of large format photodetector system in future. However, the inevitable cost of deteriorating the specific detectivity should not be ignored. And hence, junction depth and doping concentration of the absorption layer need to be balanced in actual preparation. In addition, the effects of lattice temperature on MTF and crosstalk in arrays were also discussed. The inter-pixel crosstalk deteriorates seriously as rising lattice temperature. A stronger impact of lattice temperature on MTF of larger pitch arrays has been confirmed. This work offers important reference to suppress inter-pixel crosstalk in obtaining the high-resolution imaging for InGaAs photodetector focal plane array.
关键词： InGaAs photodetector array,Three-dimensional numerical analysis,Modulation transfer function,Crosstalk
更新于2025-09-23 15:19:57
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Linear-Gompertz Model-Based Regression of Photovoltaic Power Generation by Satellite Imagery-Based Solar Irradiance
摘要： A simple yet accurate photovoltaic (PV) performance curve as a function of satellite-based solar irradiation is necessary to develop a PV power forecasting model that can cover all of South Korea, where more than 35,000 PV power plants are currently in operation. In order to express the nonlinear power output of the PV module with respect to the hourly global horizontal irradiance derived from satellite images, this study employed the Gompertz model, which is composed of three parameters and the sigmoid equation. The nonphysical behavior of the Gompertz model within the low solar irradiation range was corrected by combining a linear equation with the same gradient at the conjoint point. The overall ?tness of Linear-Gompertz regression to the 242 PV power plants representing the country was R2 = 0.85 and nRMSE = 0.09. The Gompertz model coe?cients showed normal distributions and equivariance of standard deviations of less than 15% by year and by season. Therefore, it can be conjectured that the Linear-Gompertz model represents the whole country’s PV system performance curve. In addition, the Gompertz coe?cient C, which controls the growth rate of the curve, showed a strong correlation with the capacity factor, such that the regression equation for the capacity factor could be derived as a function of the three Gompertz model coe?cients with a ?tness of R2 = 0.88.
关键词： photovoltaic system performance,Gompertz model,power output prediction,satellite-derived global horizontal irradiance,numerical analysis
更新于2025-09-23 15:19:57
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Analysis of novel passive cooling strategies for free-standing silicon photovoltaic panels
摘要： Silicon-based photovoltaic (PV) panels are sensitive to operating temperatures, especially during exposure to high solar irradiation levels. The sensitivity of PV panels is reflected through the reductions in photovoltaic energy conversion efficiency (electrical efficiency) and in PV panel lifetime due to thermal fatigue. In this study, different and novel passive cooling strategies were proposed and numerically investigated for the case of 50-W market-available free-standing silicon PV panels. The focus of the research was to examine the effect of the proposed modifications on the temperatures of the specific PV panel layers as well as on the velocity contours. The used numerical model was upgraded based on a previously developed numerical model that was validated through an experimental manner. Three different passive cooling scenarios were numerically investigated, and the most promising one was the case where the PV panel was provided with slits through the front PV panel surface resulting in a reduction of about 4 °C for the PV panel operating temperature. The other examined cases proved to be less effective with the detected temperature reduction being less than 1.0 °C. The consideration of novel PV panel frame materials was found to be a viable possibility. It was also found that all the proposed modifications can generally lead to the performance improvement in the PV panels and reduce the materials spent on the production of commercial PV panels.
关键词： Photovoltaics,Numerical analysis,Passive cooling,Renewable energy,Energy efficiency
更新于2025-09-23 15:19:57