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[IEEE 2018 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition (iWEM) - Nagoya (2018.8.29-2018.8.31)] 2018 IEEE International Workshop on Electromagnetics:Applications and Student Innovation Competition (iWEM) - A Computational Study of Indoor-to-Outdoor Propagation in Office Environment at 2.4 GHz and 5.2 GHz Bands
摘要： In this paper we predict indoor-to-outdoor radio wave propagation characteristics at frequencies of 2442 MHz and 5200 MHz using a large-scale computer simulation. A wireless LAN access point is assumed to be installed in office buildings. We discuss path loss and shadow fading in an observation plane outside the office building which faces an exterior concrete wall with windows. It is clarified from computation results that the path loss at 5200 MHz is smaller than that at 2442 MHz, and that the shadow fading distribution is expressed by a superposition of components passing through the windows and the concrete walls.
关键词： indoor-to-outdoor propagation,path loss,FDTD method,wireless LAN,shadowing
更新于2025-09-19 17:15:36
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Spectral radiative properties of skeleton inner structure of ceramic foam based on ordered opal structure model
摘要： In this work, three dimensional periodic ordered opal structures are used to model the inner structures of skeleton of porous ceramic foam. The radii of close-packed spheres range from 0.7 μm to 1.7 μm. The spectral radiative properties are predicted by applying the FDTD method to analyze the radiative transfer inside the skeleton. The characteristics of re?ection spectra and transmission spectra with increasing incident wavelength are analyzed, including the different feature regions constituting the variation curves and the red shift of variation curve with growing size of close-packed spheres. The values and characteristics of absorption peaks surrounding the locations where size parameters are approximate to 1 are compared. The BSDF of scattering power are calculated further. The transformation of transmission in incident direction and re?ection in mirror direction is shown. Then, the distribution of radiation intensity in cross sections parallel to the incident light are compared and the variety from uniform distribution to anisotropic periodic distribution is summarized. The prediction and analysis are bene?t to further researches about the radiative transfer inside the porous ceramic foam.
关键词： Spectral radiative properties,Skeleton of ceramic foam,Opal structure,FDTD
更新于2025-09-19 17:15:36
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[IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Deep Learning and Inverse Design in Plasmonic
摘要： Laser pulses can colour noble metals by inducing nanoparticles on their surface. The colours are linked to laser parameters and nanoparticles geometry. We apply deep learning to the direct prediction of colours from a laser parameter set or a nanoparticle particle distribution. A new method for inverse design via deep learning is also proposed to retrieve the appropriate laser parameters or nanoparticle distribution given the desired colour.
关键词： Inverse Design,Plasmonic Colours,FDTD,Deep Learning
更新于2025-09-19 17:13:59
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Analysis on spectral radiative properties of micro-scaled rough ligament surface inside open-cell nickel foam
摘要： Accurately predicting the spectral radiative properties of ligament surface is vital for exploring the heat transfer inside open-cell foam materials. In this work, the complex morphology of ligament surface in open-cell nickel foam is reconstructed by analyzing the SEM scanning pictures of ligament surfaces. Then, the radiative parameters including the directional-hemispherical re?ectivity, directional-directional re?ectivity and proportion of specular re?ection of rough ligament surface in the waveband from visible to near infrared light are numerically predicted by applying the FDTD method. Furthermore, the effects of incident angle and wavelength on the predicted radiative properties are compared and summarized. Besides, a ?fth-degree polynomial is put forward for characterizing the directional-hemispherical re?ectivities under different incident angles and wavelengths. The distributions of directional-directional re?ectivities of ligament surface are compared and analyzed in order to predict the various value and dominated scope of re?ection peak in the specular re?ection direction. Additionally, the proportions of specular re?ection under different incident conditions are achieved properly and characterized by proposed mathematical formulas. This work is helpful for the multi-scale numerical prediction of radiative transfer inside open-cell nickel foams, which is bene?cial to further researches about engineering applications of open-cell foam materials.
关键词： Micro scaled morphology,Spectral radiative properties,Ligament surface,FDTD
更新于2025-09-19 17:13:59
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Design and Analysis of High Efficiency Perovskite Solar Cell with ZnO Nanorods and Plasmonic Nanoparticles
摘要： Recently, the utilization of hybrid organic-inorganic perovskite has become prevalent in solar cell applications due to its promising optical properties. In this study, a perovskite solar cell (PSC) based on ZnO nanorods (NRs) as an electron transport layer (ETL) was numerically simulated and the plasmonic effects of gold nanoparticles (Au NPs) were surveyed beside the previously desirable result of using ZnO nanorod observed in 3rd generation organic photovoltaic devices. Since the unique properties of plasmonic structures, particularly the ability to guide and trap the light at nanometer dimensions, would cause a substantial increase in light absorption, improved device performance can be expected. In this article, we showed that a model of perovskite solar cell comprised of FTO/ZnO/ZnO NR/CH3NH3PbI3/spiro-MeOTAD/Au yielded promising results after incorporating Au NPs. While utilizing the benefits of ZnO nanorod ETL is a common method to achieve high-performance halide PSCs, we revealed that incorporating Au NPs between nanorods leads to an even superior behavior. After analyzing various diameters of Au nanoparticles and densities of ZnO nanorod arrays and adopting the optimum value of both, results of our simulations demonstrated that CH3NH3PbI3 perovskite infiltrated ZnO NRs solar cell with Au NPs (without Au NPs) has an efficiency of “16.77%” (14.51%), the fill factor of “78.28%” (76.60%) with a short circuit current density of “20.56 ????/????2”( 18.07 ????/????2). This drastic improvement can pave the way for further studies to fabricate and reap benefit out of the plasmonic effect in perovskite solar cells.
关键词： Perovskite solar cell,FDTD simulation,Plasmonic nanoparticles,ZnO nanorods
更新于2025-09-19 17:13:59
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Nanosecond laser-induced surface damage and its mechanism of CaF2 optical window at 248a??nm KrF excimer laser
摘要： Calcium fluoride (CaF2) crystals is a kind of important optical material for ultraviolet (UV) and deep-ultraviolet (DUV) lithography and high-power laser-related applications. However, its laser-induced damage threshold (LIDT) directly affects the laser power, so that the above-mentioned applications could be limited. Therefore, the research on the damage characteristics and laser damage resistance of caf2 crystals is urgent. A 3D Finite-Difference Time-Domain (FDTD) method with Maxwell spinor equation is used, and the results show that the electric field intensity of rear surface is larger than that of front surface, which causes a lower threshold and is consistent with the experimental observations. And a thermo-mechanical coupled finite element model (FEM) of CaF2 with ce2o3 impurities, which are introduced by polishing process, has semiquantitatively described the damage mechanism of CaF2 by 248 nm-excimer laser.
关键词： laser-induced damage,FDTD,CaF2,FEM,ultraviolet excimer laser
更新于2025-09-19 17:13:59
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Electromagnetic Wave Absorbers (Detailed Theories and Applications) || Basic Theory of Computer Analysis
摘要： One of the reasons that a wide variety of EM-wave absorber analyses came to be possible recently is the remarkable progress of modeling and computer simulation technologies. In addition, in actual computer simulation technologies, a number of theoretical analysis methods and means are compounded and systemized. In this chapter, in order to deepen the basic understanding of computer simulation analysis of EM-wave absorbers, the finite-difference time-domain (FDTD) method and finite element (FE) method are explained in detail, including their fundamental principles.
关键词： EM-wave absorbers,FDTD method,Maxwell's equations,Finite element method,Computer simulation
更新于2025-09-19 17:13:59
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[IEEE 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - HangZhou, China (2018.9.5-2018.9.7)] 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - Reconfigurable Half-Mode Substrate Integrated Waveguide Filter With Wide Out-Of-Band Rejection
摘要： A three-dimensional (3-D) finite-difference time-domain (FDTD) algorithm is used in order to simulate ground penetrating radar (GPR) for landmine detection. Two bowtie GPR transducers are chosen for the simulations and two widely employed antipersonnel (AP) landmines, namely PMA-1 and PMN are used. The validity of the modeled antennas and landmines is tested through a comparison between numerical and laboratory measurements. The modeled AP landmines are buried in a realistically simulated soil. The geometrical characteristics of soil’s inhomogeneity are modeled using fractal correlated noise, which gives rise to Gaussian semivariograms often encountered in the field. Fractals are also employed in order to simulate the roughness of the soil’s surface. A frequency-dependent complex electrical permittivity model is used for the dielectric properties of the soil, which relates both the velocity and the attenuation of the electromagnetic waves with the soil’s bulk density, sand particles density, clay fraction, sand fraction, and volumetric water fraction. Debye functions are employed to simulate this complex electrical permittivity. Background features like vegetation and water puddles are also included in the models and it is shown that they can affect the performance of GPR at frequencies used for landmine detection (0.5–3 GHz). It is envisaged that this modeling framework would be useful as a testbed for developing novel GPR signal processing and interpretations procedures and some preliminary results from using it in such a way are presented.
关键词： rough surface,GPR,water puddles,modeling,FDTD,antipersonnel (AP) landmines,roots,dispersive,fractals,Antennas,bowtie,GprMax,grass,vegetation
更新于2025-09-19 17:13:59
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Influence of TiO <sub/>2</sub> layer on ultimate efficiencies for planar and nano-textured CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> solar cells
摘要： The influence of TiO2 layer on the ultimate efficiencies, η, i.e. efficiencies without considering carrier recombination, for the planar and nano-textured CH3NH3PbI3 (MAPbI3) perovskite solar cells (SCs) are investigated. In planar TiO2/MAPbI3 heterojunction SCs, in order to achieve the largest power conversion efficiency (PCE), the TiO2 layer thickness, d1, is important. With the finite difference time domain (FDTD) method, we demonstrated that when the MAPbI3 layer thickness, d2, is 250 nm, which is a common-most MAPbI3 layer thickness for perovskite SCs, η achieves maximum when d1 is 80 nm. Fabricating nano textures on SC surface is an important method to improve the PCE. We studied the effects of d1 and d2 on the optimized η, η0, for two kinds of nano-textured perovskite SCs: the SCs with the nontextured TiO2 layer and the column-shaped nano hollow (CLH) textured MAPbI3 layer, defined as the nontextured-TiO2/CLH-MAPbI3 SCs, and the SCs with CLH textured TiO2 and CLH textured MAPbI3 layers of the same hollow axes and radius, defined as the CLH-(TiO2/MAPbI3) SCs. Generally, when d1 and d2 are fixed, η0 for the CLH-(TiO2/MAPbI3) SC is larger than that for the nontextured-TiO2/CLH-MAPbI3 SC by ca. 5%.
关键词： power conversion efficiency,perovskite solar cell,FDTD method,nano texture,light absorption
更新于2025-09-19 17:13:59
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Enhancing effects of reduced graphene oxide on photoluminescence of CsPbBr <sub/>3</sub> perovskite quantum dots
摘要： The composites of CsPbBr3 perovskite quantum dots (PeQDs) and reduced graphene oxide (RGO) nanosheets have been synthesized by an in-situ solution reaction. The amount of RGO can significantly affect the photoluminescence of PeQDs. Varying with the amount of RGO, the photoluminescence quantum yield can be tuned from 48.4% to 69.3%. PL decay analysis indicates that the radiative decay rate and charge transfer become faster with increasing the amount of RGO. The ellipsomitric data can be described by a double Lorentz oscillator model. The comparison between bare and composite samples indicates that the complex refractive index can be affected by RGO composite. Numerical simulations on the electric field distribution for PeQD/RGO show that the local electric field around CsPbBr3 QDs is increased by surface plasmon resonance on the surface of RGO nanosheet. These results suggest that PeQD/RGO composite can be used for highly efficient light emitting devices.
关键词： FDTD,Surface plasmon resonance,Photoluminescence,Reduced graphene oxide,CsPbBr3 quantum dots
更新于2025-09-19 17:13:59