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- 摘要
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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 precision mapping of single-pixel Silicon Drift Detector for applications in astrophysics and advanced light source
摘要： A Silicon Drift Detector with 3 × 3 mm2 sensitive area was designed by INFN of Trieste and built by FBK-Trento. It represents a single-pixel precursor of a monolithic matrix of multipixel Silicon Drift Detectors and, at the same time, a model of one cell Fluorescence Detector System (XAFS) for SESAME. The point-by-point mapping tests of the detector were carried out in the X-ray facilities at INAF-IAPS in Rome, equipped with a motorized two-axis micrometric positioning system. High precision characterization of this detector was done with a radioactive 55Fe source and a collimated Ti X-ray tube equipped with a Bragg crystal monocromator. The mapping in different positions and bias condition was specifically-aimed to the detailed analysis of the charge collection efficiency at the edge of the detector. The result is important to understand and verify the aspects related to the collection of the signal with respect to the position of interactions of the photons, especially in consideration of the new design and development of monolithic multipixel detectors.
关键词： SDD,Silicon drift detectors,Mapping
更新于2025-09-23 15:23:52
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A Dual-Discrete Model Predictive Control-based MPPT for PV systems
摘要： This paper presents a method that overcomes the problem of the confusion during fast irradiance change in the classical MPPTs as well as in model predictive control (MPC)-based MPPTs available in the literature. The previously introduced MPC-based MPPTs take into account the model of the converter only, which make them prone to the drift during fast environmental conditions. Therefore, the model of the PV array is also considered in the proposed algorithm, which allows it to be prompt during rapid environmental condition changes. It takes into account multiple previous samples of power, and based on that is able to take the correct tracking decision when the predicted and measured power differ (in case of drift issue). After the tracking decision is taken, it will be sent to a second part of the algorithm as a reference. The second part is used for following the reference provided by the first part, where the pulses are sent directly to the converter, without a modulator or a linear controller. The proposed technique is validated experimentally by using a buck converter, fed by a PV simulator. The tracking efficiency is evaluated according to EN50530 standard in static and dynamic conditions. The experimental results show that the proposed MPC-MPPT is a quick and accurate tracker under very fast changing irradiance, while maintaining high tracking efficiency even under very low irradiance.
关键词： Buck converter,dc-dc power conversion,Photovoltaic systems,Double cost function,Maximum power point tracking,Drift,EN50530 standard,MPC
更新于2025-09-23 15:22:29
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[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - Extended Map-Drift Algorithm for Spaceborne Sliding Spotlight SAR Data
摘要： For flexibly steering antenna in along-track direction, space-borne synthetic aperture radar (SAR) can achieve high resolution with wide swath conveniently, especially in sliding spotlight mode. In order to overcome azimuth folding effects in this mode, the three-step focusing algorithm was been proposed. However it is difficult to perform fine focus of image due to Doppler rate errors. In this paper, a kind of auto-focusing approach based on Map-Drift (MD) is proposed, which is compatible with the three-step imaging algorithm and efficient. Firstly, the Doppler-rate error transfer mechanism in de-ramp operation (the third step of the three-step focusing algorithm) is illustrated. Secondly, the accurate images draft due to Doppler-rate error is conduced based on this mechanism. Thirdly, a new efficient strategy of iteration is present. Finally, the validness and efficiency of the proposed approach is tested by simulation data and real SAR data.
关键词： synthetic aperture radar (SAR),Map-Drift,auto-focusing,sliding spotlight,focusing algorithm,three-step approach
更新于2025-09-23 15:22:29
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Parallel domain decomposition methods for a quantum-corrected drift–diffusion model for MOSFET devices
摘要： In this paper, we describe parallel domain decomposition methods based on the restricted additive Schwarz (RAS) method for a quantum-corrected drift-diffusion (QCDD) model for MOSFET devices. We have developed hybrid Message Passing Interface (MPI)/OpenMP parallelization algorithms of the QCDD system. For internode parallelization, two extensions of the RAS method are newly developed for the QCDD model. For intranode parallelization, we combine the conjugate gradient (CG) and BiCGSTAB procedures with a splitting-up operator method to realize parallelization of the incomplete factorization. The parallel numerical results for a three-dimensional Si bulk n-MOSFET on a multi-core NEC SX-ACE parallel computer are demonstrated. The intranode parallel numerical results are further evaluated on a many-core Cray XC40 parallel computer.
关键词： Restricted additive Schwarz method,Domain decomposition method,Numerical methods,Device simulation,Semiconductor,quantum-corrected drift–diffusion model
更新于2025-09-23 15:21:21
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Coupled 3D master equation and 1D drifta??diffusion approach for advanced OLED modeling
摘要： A novel simulation approach for excitonic organic light-emitting diodes (OLEDs) is established by combining a continuous one-dimensional (1D) drift-diffusion (DD) model for the charge carrier dynamics with a three-dimensional (3D) master equation (ME) model describing the exciton dynamics in a multi-layer OLED stack with an additional coupling to a thin-film optics solver. This approach effectively combines the computational efficiency of the 1D DD solver with the physical accuracy of a discrete 3D ME model, where excitonic long-range interactions for energy transfer can be taken into account. The coupling is established through different possible charge recombination types as well as the carrier densities themselves. We show that such a hybrid approach can efficiently and accurately describe steady-state and transient behavior of optoelectronic devices reported in literature. Such a tool will facilitate the optimization and characterization of multilayer OLEDs and other organic semiconductor devices.
关键词： drift-diffusion,excitons,master equation,OLED
更新于2025-09-23 15:21:01
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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - [Copyright notice]
摘要： Doppler velocity can be derived by calculating Doppler shift anomalies between predicted and estimated Doppler centroids. The predicted Doppler centroid is calculated based on a geometric model of satellite assuming that the target is not moving. The estimated Doppler centroid can be directly extracted from the raw SAR signal data by applying the average cross-correlation coefficient method. It is known that wind-generated ocean waves can significantly contribute to Doppler velocity due to the correlation between orbital motions of the waves and (tilt and hydrodynamic) modulated radar cross sections, in addition to what sea surface current contributes. In this study, the characteristics of Doppler velocities under hurricane conditions were investigated using RADARSAT-1 ScanSAR raw data. Five different hurricanes (Hurricane Dean, Hurricane Ivan, Hurricane Kyle, Hurricane Lili, and Typhoon Xangsane) and sequential acquisitions of two hurricanes (Hurricane Kyle and Hurricane Lili) were selected to study the contribution of wind-induced waves to Doppler velocities and compared with in situ measurements of drifting buoys. The results show that hurricane-generated seas and associated winds and waves appear to be different from ordinary sea state. This leads to lower estimates of Doppler velocities than expected and much closer to sea surface current velocities.
关键词： RADARSAT,Doppler velocity,hurricane,drift current,wind-induced waves
更新于2025-09-23 15:21:01
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The Critical Role of AlInP Window Design in IIIa??V Rear-Emitter Solar Cells
摘要： Doppler velocity can be derived by calculating Doppler shift anomalies between predicted and estimated Doppler centroids. The predicted Doppler centroid is calculated based on a geometric model of satellite assuming that the target is not moving. The estimated Doppler centroid can be directly extracted from the raw SAR signal data by applying the average cross-correlation coefficient method. It is known that wind-generated ocean waves can significantly contribute to Doppler velocity due to the correlation between orbital motions of the waves and (tilt and hydrodynamic) modulated radar cross sections, in addition to what sea surface current contributes. In this study, the characteristics of Doppler velocities under hurricane conditions were investigated using RADARSAT-1 ScanSAR raw data. Five different hurricanes (Hurricane Dean, Hurricane Ivan, Hurricane Kyle, Hurricane Lili, and Typhoon Xangsane) and sequential acquisitions of two hurricanes (Hurricane Kyle and Hurricane Lili) were selected to study the contribution of wind-induced waves to Doppler velocities and compared with in situ measurements of drifting buoys. The results show that hurricane-generated seas and associated winds and waves appear to be different from ordinary sea state. This leads to lower estimates of Doppler velocities than expected and much closer to sea surface current velocities.
关键词： RADARSAT,Doppler velocity,hurricane,drift current,wind-induced waves
更新于2025-09-23 15:21:01
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Manganese doping stabilizes perovskite light-emitting diodes by reducing ion migration
摘要： Lead halide perovskite light-emitting diodes have recently emerged as high-performance devices. However, they degrade rapidly. This degradation has been attributed to the mixed ionic-electronic nature of these perovskites. Manganese doping increases the stability of perovskite light-emitting diodes, but the effects of manganese doping on ion migration are not well understood. We use impedance spectroscopy and transient ion-drift measurements to study the effect of manganese doping on ion migration in PEABr0.2Cs0.4MA0.6PbBr3 quasi-bulk 2D/3D perovskite light-emitting diodes. We find that manganese doping enhances the activation energy for ion migration two fold and reduces the diffusion coefficient. These changes in the behavior of mobile ions help to explain the improved stability in perovskite light-emitting diodes upon manganese doping and lead to a better understanding of the influence of passivating agents on ion migration and thus on the stability of the devices.
关键词： capacitance,perovskites,manganese,mobile ions,transient ion drift,impedance,light-emitting diodes
更新于2025-09-23 15:21:01
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Electrolyte-Insulator-Semiconductor pH Sensors with Arrayed Patterns Manufactured by Nano Imprint Technology
摘要： This work focuses on the sensing properties of electrolyte-insulator-semiconductor (EIS) pH sensors with arrayed patterns manufactured by integrating nano imprint technology (NIL) and CMOS process. The arrayed patterns, made of line and square at about ～200–400nm with a width/space ratio of about ～1/1-1/2, were fabricated by NIL; followed by the manufacturing of the EIS sensors. The patterns were studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The sensors, with arrayed patterns, all exhibited higher sensitivity, lower hysteresis, and lower drift properties than the single one did. The effects of arrayed patterns (square or line) and pattern density on the sensing area were also investigated. With this approach, the sensors can be fabricated for future high performance biochemical sensing applications.
关键词： sensitivity,drift,arrayed patterns,nano imprint technology,pH sensors,electrolyte-insulator-semiconductor,hysteresis
更新于2025-09-23 15:21:01