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Dynamic theory of nanophotonic control of two-dimensional semiconductor nonlinearities
摘要： We introduce a Maxwell-Bloch simulation approach which self-consistently combines a microscopic description of the carrier and polarization dynamics of a transition-metal-dichalcogenide (TMDC) monolayer with a spatiotemporal full-wave time-domain simulation of Maxwell’s equations on the basis of a ?nite-difference time-domain (FDTD) method beyond the slowly varying amplitude or paraxial approximations. This offers a platform to realistically model, in particular, the typical ultrafast optical excitation experiments in micro- and nanocavities. Our simulations con?rm that the weak screening of the Coulomb interaction in TMDC monolayers yields pronounced exciton lines in the linear spectrum and we uncover the second-order nonlinearity represented in the semiconductor Maxwell-Bloch equations by an intraband dipole moment. This allows us to calculate the spectral shape of the exceptionally strong second-harmonic generation around the exciton lines of TMDC monolayers. We demonstrate that the second-harmonic signal can remarkably be further enhanced by several orders of magnitude through a suitably designed (one-dimensional) photonic microcavity. Due to its self-consistency, ?exibility, explicit spatio-temporal resolution on the nanoscale and the ready access to light ?eld and electron dynamics, our theory and computational approach is an ideal platform to design and explore spatiotemporal nonlinear and quantum dynamics in complex photonic or plasmonic micro- and nanostructures for optoelectronic, nanophotonic and quantum applications of TMDC monolayers.
关键词： second-harmonic generation,nonlinear optical response,TMDC monolayer,Maxwell-Bloch simulation,photonic microcavity
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Kota Kinabalu, Malaysia (2018.10.7-2018.10.10)] 2018 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Modifications to Accelerate the Iterative Algorithm for the Two-diode Model of PV Module
摘要： This work proposes two modifications—namely Adaptive Search Range (ASR) and improved Newton-Raphson Method (iNRM), to enhance the computation speed of the iterative computational method for the two-diode model. These modifications significantly improve the computation speed without introducing any compromise in terms of accuracy. Moreover, they are very simple to implement and do not require any additional information as input. By implementing ASR, the algorithm is only required to calculate a fraction (25%) of the P- V curve at every iteration. On the other hand, the iNRM improves the calculation of the curve by guiding the initial value of current for each point of voltage. To evaluate their effectiveness, the original algorithm and its modified versions are coded in Matlab script. They are used to identify the model parameters of three PV modules of different technologies. The computation time of the algorithm with both ASR and iNRM implemented is observed to be up to 4.7 times faster. Furthermore, the values of the model parameters are computed to be exactly equal—which implies that the accuracy of the original algorithm the is retained. With these merits, the modifications are envisaged to be critical improvements to the algorithm, especially for application in computers with lower specifications.
关键词： photovoltaic,pv modelling,two-diode model,simulation
更新于2025-09-09 09:28:46
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Transfer Learning from Synthetic to Real Images Using Variational Autoencoders for Precise Position Detection
摘要： Capturing and labeling camera images in the real world is an expensive task, whereas synthesizing labeled images in a simulation environment is easy for collecting large-scale image data. However, learning from only synthetic images may not achieve the desired performance in the real world due to a gap between synthetic and real images. We propose a method that transfers learned detection of an object position from a simulation environment to the real world. This method uses only a significantly limited dataset of real images while leveraging a large dataset of synthetic images using variational autoencoders. Additionally, the proposed method consistently performed well in different lighting conditions, in the presence of other distractor objects, and on different backgrounds. Experimental results showed that it achieved accuracy of 1.5mm to 3.5mm on average. Furthermore, we showed how the method can be used in a real-world scenario like a “pick-and-place” robotic task.
关键词： variational autoencoder,transfer learning,position detection,deep learning,computer simulation
更新于2025-09-09 09:28:46
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[IEEE 2018 International Semiconductor Conference (CAS) - Sinaia, Romania (2018.10.10-2018.10.12)] 2018 International Semiconductor Conference (CAS) - Numerical Simulations of Radiation Damage Effects in Active-Edge Silicon Pixel Sensors for High-Energy Physics Experiments
摘要： High-energy physics experiments at the future CERN High Luminosity LHC (Large Hadron Collider) require highly segmented pixelated sensors of increased geometrical efficiency and the ability of withstanding extremely high radiation damage. The performance of planar n-on-p sensors with active edges is simulated at very high fluences (2×1016 neq/cm2), using a recent three level trap model for p-type silicon material. Precise structural definition is achieved by investigating the doping pro(cid:191)le of the devices via the Secondary Ion Mass Spectrometry technique. The breakdown voltage, and hole density distribution are studied as a function of radiation fluences.
关键词： TCAD simulation,radiation damage,Active edge sensor
更新于2025-09-09 09:28:46
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Development and Application of FMO Calculation ? DPD Simulation Conbination Scheme; FMO計算-粗視化シミュレーション連携手法の開発と応用;
摘要： We have been developing a combination scheme of fragment molecular orbital (FMO) calculations and dissipative particle dynamics (DPD) simulations in order to predict the structure of functional materials. FMO-DPD simulations for polymer electrolyte membrane, lipid membrane, and protein model were conducted using in-house automatic parameter determination software.
关键词： Fragment Molecular Orbital Method,Lipid Membrane,FMO-DPD Simulation,Polymer Electrolyte Membrane
更新于2025-09-04 15:30:14
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ANALYSIS AND DESIGN OF RECTANGULAR UNIAXIAL AND BIAXIAL ANISOTROPIC DIELECTRIC RESONATOR ANTENNAS
摘要： An anisotropic dielectric resonator antenna (ADRA) with uniaxial and biaxial permittivity tensors is characterized by using the dielectric waveguide model. An approximate formula for the Q factor of ADRA is derived. Then, it is shown that by certain conditions a wideband ADRA can be designed. Samples of simulation results are shown to demonstrate the capabilities of the proposed anisotropic technique for enhancing the bandwidth of ADRA. The proposed antenna is simulated by two full wave packages, Ansoft HFSS and CST Microwave Studio, and a good agreement is observed among the results.
关键词： anisotropic dielectric resonator antenna,simulation,dielectric waveguide model,permittivity tensors,CST Microwave Studio,wideband,biaxial,Ansoft HFSS,Q factor,uniaxial
更新于2025-09-04 15:30:14
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Numerical Simulation of Plasmon Excitation in Gold Nanostructure of the Parabolic Nanoantenna Type
摘要： Experimentally obtained nanostructures shaped as a through hole with a particle at the center are considered. Their electrodynamic parameters are studied using numerical simulation methods. It is shown that such structures function similarly to parabolic antennas.
关键词： numerical simulation of electrodynamics,nanostructuring of thin films,parabolic nanoantennas
更新于2025-09-04 15:30:14
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Enhanced Sensing Performance of Integrated Gas Sensor Devices
摘要： Semiconducting metal oxide (SMO) gas sensors, dedicated to wearable devices were designed, fabricated, and characterized in terms of power consumption, thermal distribution, and sensing capability. The sensors demonstrate a sensitivity down to ppb-level VOC concentrations at a low power consumption of 10.5 mW. To further enhance the baseline stability and sensing response characteristics at low power consumption, a new sensor structure is proposed. The design implements novel aspects in terms of fabrication and microheater geometry, leading to improved sensor performance which enables new applications for SMO gas sensors. In this work, two designs were analyzed using experimental characterization and simulation. The results of the analyses of the two sensors are comparatively reported.
关键词： microheater,electo-thermal simulation,gas sensor,semiconducting metal oxide
更新于2025-09-04 15:30:14
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Modelling of XCO2 Surfaces Based on Flight Tests of TanSat Instruments
摘要： The TanSat carbon satellite is to be launched at the end of 2016. In order to verify the performance of its instruments, a ?ight test of TanSat instruments was conducted in Jilin Province in September, 2015. The ?ight test area covered a total area of about 11,000 km2 and the underlying surface cover included several lakes, forest land, grassland, wetland, farmland, a thermal power plant and numerous cities and villages. We modeled the column-average dry-air mole fraction of atmospheric carbon dioxide (XCO2) surface based on ?ight test data which measured the near- and short-wave infrared (NIR) re?ected solar radiation in the absorption bands at around 760 and 1610 nm. However, it is dif?cult to directly analyze the spatial distribution of XCO2 in the ?ight area using the limited ?ight test data and the approximate surface of XCO2, which was obtained by regression modeling, which is not very accurate either. We therefore used the high accuracy surface modeling (HASM) platform to ?ll the gaps where there is no information on XCO2 in the ?ight test area, which takes the approximate surface of XCO2 as its driving ?eld and the XCO2 observations retrieved from the ?ight test as its optimum control constraints. High accuracy surfaces of XCO2 were constructed with HASM based on the ?ight’s observations. The results showed that the mean XCO2 in the ?ight test area is about 400 ppm and that XCO2 over urban areas is much higher than in other places. Compared with OCO-2’s XCO2, the mean difference is 0.7 ppm and the standard deviation is 0.95 ppm. Therefore, the modelling of the XCO2 surface based on the ?ight test of the TanSat instruments fell within an expected and acceptable range.
关键词： XCO2 simulation,TanSat,XCO2 retrieval,HASM,?ight test
更新于2025-09-04 15:30:14
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Accurate and efficient analysis of the upward heat flow in InGaP/GaAs HBTs through an automated FEM-based tool and Design of Experiments
摘要： This paper presents an extensive analysis aimed at quantifying the impact of all the key technology parameters on the upward heat flow in state‐of‐the‐art InGaP/GaAs heterojunction bipolar transistors (HBTs) for various emitter areas and shapes. Extremely accurate thermal simulations are conducted in a relatively short time with a tool relying on a commercial 3‐D finite‐element method (FEM) solver and an in‐house routine for automated geometry construction, optimized mesh generation, sequential solution, and data storing/processing. Design of Experiments is used to define a thermal resistance model as a function of the aforementioned parameters on the basis of a few FEM data.
关键词： finite‐element method (FEM),gallium arsenide (GaAs),Design of Experiments (DOE),thermal simulation,thermal resistance,heterojunction bipolar transistor (HBT)
更新于2025-09-04 15:30:14