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[IEEE 2020 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus) - St. Petersburg and Moscow, Russia (2020.1.27-2020.1.30)] 2020 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus) - The Automated Test Bench for Studying the Parameters of a Laser Beam Near the Surface of Short-Focus Optical System
摘要： A general framework to combine the finite-difference time-domain (FDTD) and the finite-element time-domain (FETD) formulations, both based on the vector wave equation, is proposed. In contrast to the existing stable hybrid FETD-FDTD, there is no transition layer between two subdomains. In addition, the stability of the proposed approach is analytically proved. This framework allows combining different FDTD and FETD formulations together. Particularly, a fully unconditionally stable hybrid method is proposed, which is proved to be energy conservative too. The key ingredient is a finite-element tearing and interconnecting method for electromagnetic problems with a new interface condition that preserves the stability of the numerical method in each region. Several numerical examples are considered in order to validate the proposed methods. The numerical results match with the reference solutions very well in all cases.
关键词： Finite-difference time-domain (FDTD) method,finite-element tearing and interconnecting (FETI),nonoverlapping,finite-element time-domain (FETD) method
更新于2025-09-23 15:21:01
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Analysis of Approaches for Modeling the Low Frequency Emission of LED Lamps
摘要： Light emitting diode (LED) lamps are now an established lighting technology, which is becoming prevalent in all load sectors. However, LED lamps are non-linear electrical loads, and their impact on distribution system voltage quality must be evaluated. This paper provides a detailed analysis of time domain and frequency domain approaches for developing and evaluating models suitable for use in large scale steady-state harmonic power ?ow analysis of the low frequency (LF) emission of LED lamps. The considered approaches are illustrated using four general categories of LED lamps, which have been shown to cover the vast majority of LED lamps currently available on the market. The aim is an in-depth assessment of the ability of commonly applied models to represent the speci?c design characteristics of different categories of LED lamps. The accuracy of the models is quantitatively evaluated by means of laboratory tests, numerical simulations, and statistical analyses. This provides an example, for each LED lamp category, of comprehensive information about the overall accuracy that can be achieved in the general framework of large scale LF harmonic penetration studies, particularly in the assessment of voltage quality in low voltage networks and their future evolution.
关键词： power system harmonics,component-based model,frequency-domain model,time-domain analysis,LED lamps
更新于2025-09-23 15:21:01
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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) - Design and performance analysis of WDM optical Communication system with EDFA-DCF and FBG for dispersion compensation using $8\mathrm{x}5$ Gbps data rate
摘要： The way in which electromagnetic ?elds are transmitted and received by ground penetrating radar (GPR) antennas is crucial to the performance of GPR systems. Simple antennas have been characterized by analyzing their radiation patterns and directivity. However, there have been limited studies that combine real GPR antennas with realistic environments, which is essential to capture the complex interactions between the antenna and surroundings. We have investigated the radiation characteristics and sensitivity of a GPR antenna in a range of lossy dielectric environments using both physical measurements and a three-dimensional (3-D) ?nite-difference time-domain (FDTD) model. Experimental data were from measured responses of a target positioned at intervals on the circumference of a circle surrounding the H-plane of the antenna. A series of oil-in-water emulsions as well as tap water were used to simulate homogeneous materials with different permittivities and with complex conductivities. Numerical radiation patterns were created utilizing a detailed 3-D FDTD model of the antenna. Good correlation was shown between the experimental results and modeled data with respect to the strength of the main lobe within the critical angle window. However, there are discrepancies in the strength of main lobe at shallow angles. In all the dielectrics, the main lobes are generally broad due to the near-?eld observation distance but, as expected, become narrower with increasing permittivity. These results provide con?dence for further use of the FDTD antenna model to investigate scenarios such as larger observation distances and heterogeneous environments that are dif?cult to study experimentally.
关键词： electromagnetic modeling,Antenna measurements,?nite-difference time-domain (FDTD),antenna radiation patterns,broadband antennas
更新于2025-09-23 15:21:01
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[IEEE 2019 International Applied Computational Electromagnetics Society Symposium - China (ACES) - Nanjing, China (2019.8.8-2019.8.11)] 2019 International Applied Computational Electromagnetics Society Symposium - China (ACES) - Double-Ridge Waveguide Mode Analysis based on FDTD-SVD Method
摘要： In this paper,hybrid finite-difference time-domain method(FDTD) and singular value decomposition(SVD),denoted by FDTD-SVD,is applied to analyze the double-ridge waveguide dominant mode. Double-ridge waveguide (WRD) without fillets and WRD with small fillets are analyzed.The simulation results show WRD without fillets can achieve a single-mode operation of 10TE from 35GHz to 112 GHz. For WRD with small fillets, its single-mode operation frequency band is 35-116GHz.These results are almost consistent with the detailed parametric study result(38-120GHz)based on Ansys HFSS, which proves that the FDTD-SVD method is simple and more effective. In addition, the transmission performance of WRD can be improved by adding fillets and enlarging the radius of fillets.
关键词： mode analysis,singular value decomposition(SVD),finite-difference time-domain method(FDTD),double-ridge waveguide(WRD)
更新于2025-09-23 15:21:01
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Waveguide Components and Aperture Antennas with Frequency-and Time-Domain Selectivity Properties
摘要： Filtering modules are essential devices of modern microwave systems given their capability to improve the signal-to-noise ratio of the received signal or to eliminate the unwanted interferences. For discriminating between different components, a filter exhibits a frequency-selective response that, however, is not able to distinguish between different signals whose spectrum falls within the pass-band of the filter itself. In this regard, some electromagnetic structures exhibiting, at the same frequency, different responses depending on the waveform of the incoming waves have been recently proposed. In this paper, we extend the aforementioned approach to the case of a standard waveguide filtering module. In particular, by loading a band-pass filtering iris with a proper lumped-element circuit, we design a waveguide component able to distinguish between different pulsed waves, even at the same frequency, depending on their pulse width. Moreover, by using this filter for capping an open-ended rectangular waveguide, a radiating element with both frequency- and time-domain selectivity properties is presented. The structures discussed in this paper may pave the way to a new class of microwave systems that, being both frequency and time selective, are less sensitive to noise and interferences.
关键词： filtering modules,time-domain response,waveguide components,waveform selectivity
更新于2025-09-23 15:21:01
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A temperature-controlled laser hot needle with grating sensor for liver tissue tract ablation
摘要： Body-centric wireless communication (BCWC) is affected by many uncertain factors. Available propagation models aim to characterize the radio propagation behavior for a speci?c scenario; model selection is based on the a posteriori knowledge from previous experience. To generalize existing parametric propagation models, the (cid:96)1-norm probability propagation model, which is independent of a posteriori knowledge, was developed in this paper. To validate the (cid:96)1-based model, Duke phantom was used as the carrier in the ?nite-difference time-domain calculation. Simulation and experimental results demonstrated that the generalized (cid:96)1-norm propagation model is very appropriate for BCWC, which always undergoes various changes in practice.
关键词： norm,?nite-difference time-domain,Body-centric networks
更新于2025-09-23 15:21:01
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Enhancement of Infrared Photo-responses of the Schottky Gate Region of an n-AlGaAs/GaAs Heterojunction FET by a Second Light Illumination
摘要： As children develop, they differ from adults in a number of important ways, including anatomy, metabolism, immune system, and the extent of myelination of the nervous system. As a consequence, equivalent exposures to radiation from mobile phones result in different doses to specific tissues in children compared with adults. Higher doses are likely to have more severe implications in the young. A young child’s skull is not only smaller and thinner than an adult’s, but also has dielectric characteristics closer to those of soft tissues, probably due to a higher water content. The young skull better matches the electromagnetic characteristics of the skin and brain. As a result, finite-difference time-domain (FDTD) simulations confirm field penetration and higher specific absorption rate (SAR) in deeper structures in the young brain. If the peak spatial SAR (psSAR) is modeled in the entire head, as current testing standards recommend, the results for adults and children are equivalent. Our anatomically based evaluations rely on FDTD simulations of different tissues within the brain and confirm that the psSAR in a child’s brain is higher than in an adult’s brain.
关键词： dosimetry,mobile phone certification,finite-difference time-domain simulation,Specific absorption rate
更新于2025-09-23 15:21:01
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Terahertz electromagnetic waves radiated from coherent longitudinal optical (LO) phonons and LO-phonon plasmon coupled modes in (001)-, (110)-, and (111)-oriented semi-insulating GaAs single crystals
摘要： We report on terahertz electromagnetic waves from coherent longitudinal optical (LO) phonons and coherent LO-phonon plasmon coupled (LOPC) modes in (001)-, (110)-, and (111)-oriented semi-insulating GaAs single crystals. The coherent LO phonons and coherent LOPC modes are observed in the three samples. In contrast, coherent transverse optical (TO) phonons are not observed in the (110)- and (111)-oriented samples in spite of that the TO phonon is the Raman active mode. We conclude that only the coherent longitudinal oscillating polarization such as coherent LO phonons and coherent LOPC modes radiate the terahertz wave and that the Raman selection rule does not contribute to the terahertz-wave-radiation process. The photogenerated electron-density dependence of the frequencies of the coherent LOPC mode is almost the same in the three samples. This ?nding indicates that the coupling of the LO phonon with the plasmon is not in?uenced by the surface orientations of the three samples.
关键词： coherent LO-phonon plasmon coupled mode,coherent longitudinal optical (LO) phonon,terahertz time-domain spectroscopy,coherent transverse optical phonon,ultrafast phenomena,Raman scattering effect
更新于2025-09-23 15:21:01
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Block Copolymer Derived Vertically Coupled Plasmonic Arrays for Surface-Enhanced Raman Spectroscopy
摘要： A surface-enhanced Raman spectroscopy sensing template consisting of gold-covered nanopillars is developed. The plasmonic slab consists of a perforated gold film at the base of the nanopillars and a Babinet complementary dot array on top of the pillars. The nanopillars were fabricated by the incorporation of an iron salt precursor into a self-assembled block copolymer thin film and subsequent reactive ion etching. The preparation is easy, scalable, and cost-effective. We report on the increase in surface-enhanced Raman scattering efficiency for smaller pillar heights and stronger coupling between the dot array and perforated gold film with average enhancement factors as high as 107. In addition, the block copolymer-derived templates show an excellent relative standard deviation of 8% in the measurement of the Raman intensity. Finite difference time domain simulations were performed to investigate the nature of the electromagnetic near-field enhancement and to identify plasmonic hot spots.
关键词： block copolymer lithography,finite difference time domain simulation,SERS uniformity,plasmonic nanomaterials,surface-enhanced Raman spectroscopy,nanofabrication,4-aminothiophenol
更新于2025-09-23 15:21:01
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Tunable graphene-on-insulator band-stop filter at the mid-infrared region
摘要： This paper presents a novel graphene-on-insulator (GOI) band-stop filter in the mid-infrared region. The finite-difference time-domain method is used to model our GOI basic and advanced filters and calculate their transmission spectra for different graphene layers at every gate-source voltage. The numerical results reveal the resonance wavelength, modulation depth, and bandwidth of the advanced filter can be tuned in the range of 11.5 to 30 μm, ?57 to ?60 dB, and 2 to 4 μm, respectively. These results are obtained by variation of the physical parameters, such as the number of overlapped filters, the number of graphene layers, and the applied chemical potential. Our results indicate that the proposed advanced band-stop filter is an excellent device to be used in an ultra-fast active graphene-based plasmonic systems for THz applications.
关键词： Finite-difference time-domain,Graphene-on-insulator,Transmission,Mid-infrared,Band-stop filter
更新于2025-09-23 15:21:01