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An advanced numerical technique for a quasi-static electromagnetic field simulation based on the finite-difference time-domain method

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JOURNAL OF COMPUTATIONAL PHYSICS 2018年 373卷 917-923页

作者： Kim, Minhyuk Park, Sangwook Jung, Hyun-Kyo Seoul Natl Univ Dept Elect & Comp Engn Seoul South Korea Korea Automot Technol Inst Corp Support & Reliabil Div EMI EMC R&D Ctr ICE Convergence Res Team Cheonan South Korea

In this paper, an advanced numerical technique is proposed for a low-frequency electromagnetic field simulation. The finite difference time domain (FDTD) method is one of the best methods for analyzing electromagnetic field problems, which require high levels of precision, such as a heterogeneous whole-body voxel human model. However, directly using the standard FDTD method in the quasi-static frequency band requires an extra-large number of iterations. We overcome this drawback using the hybrid of surface equivalence theorem and quasi-static FDTD (QS-FDTD) method. The surface equivalence theorem is used to consider arbitrary shape of source and the QS-FDTD is applied to obtain electromagnetic response quickly in the low-frequency region. The results of the proposed method are in good agreement with those from a commercial electromagnetic simulator. The proposed method is valid where the quasi-static approximation is satisfied. (C) 2018 Elsevier Inc. All rights reserved.

关键词： finite-difference time-domain method Surface equivalence theorem Quasi-static analysis

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Non-standard finite-difference time-domain method for solving the Schrodinger equation

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PRAMANA-JOURNAL OF PHYSICS 2018年第4期91卷 1-7页

作者： Sudiarta, I. Wayan Univ Mataram Fac Math & Nat Sci NTB Phys Study Program Mataram Ntb Indonesia

In this paper, an improvement of the finite-difference time-domain (FDTD) method using a non-standard finite-difference scheme for solving the Schrodinger equation is presented. The standard numerical scheme for a second derivative in the spatial domain is replaced by a non-standard numerical scheme. In order to apply the non-standard FDTD (NSFDTD), first, the estimates of eigenenergies of a system are needed and computed by the standard FDTD method. These first eigenenergies are then used by the NSFDTD method to obtain improved eigenenergies. The NSFDTD method can be employed iteratively using the resulting eigenenergies to obtain more accurate results. In this paper, the NSFDTD method is validated using infinite square well, harmonic oscillator and Morse potentials. Significant improvements are found when using the NSFDTD method.

关键词： time-dependent Schrodinger equations non-standard finite difference method finite-difference time-domain method eigenvalues eigenfunctions

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Investigation of three-pulse photon echo in thick crystal using finite-difference time-domain method

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Chinese Physics B 2017年第4期26卷 190-197页

作者：马秀荣徐林常世元张双根 Department of Computer and Communication Engineering Tianjin University of TechnologyTianjin 300384China Engineering Research Center of Communication Devices and Technology Ministry of EducationTianjin Key Laboratory of Film Electronic and Communication DevicesTianjin 300384China 不详

This paper investigates the phenomenon of three-pulse photon echo in thick rare-earth ions doped crystal whose thickness is far larger than 0.002 cm which is adopted in previous *** influence of thickness on the three-pulse photon echo＇s amplitude and efficiency is analyzed with the Maxwell-Bloch equations solved by finite-difference timedomain *** demonstrate that the amplitude of three-pulse echo will increase with the increasing of thickness and the optimum thickness to generate three-pulse photon echo is 0.3 cm for Tm^（3＋）：YAG when the attenuation of the input pulse is taken into ***,we find the expression 0.09 exp（α＇L）,which is previously employed to describe the relationship between echo＇s efficiency and thickness,should be modified as 1.3 · 0.09 exp（2.4 ·α＇L） with the propagation of echo considered.

关键词： three-pulse photon echo Maxwell-Bloch equations finite-difference time-domain method

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Extension of the Magnetically Mixed Newmark-Leapfrog finite-difference time-domain method to Debye Dispersive Media

Extension of the Magnetically Mixed Newmark-Leapfrog Finite-...

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IEEE International Conference on Computational Electromagnetics (ICCEM)

作者： Fujita, Kazuhiro Fujitsu Ltd Tech Comp Solut Unit Mihama Ku 9-3 Nakase 1 Chome Chiba Chiba 2618588 Japan

ISBN: (纸本)9781509010387

In this paper, the magnetically mixed Newmark-Leapfrog finite-difference time-domain (MNL-FDTD) method is extended into a Debye model of dielectric dispersion. A frequency-dependent MNL-FDTD scheme is formulated which is based on the recursive convolution formulation in time domain. The resultant scheme has a relaxed stability condition even in the time domain analysis of thin dielectric structures with the Debye model. The input impedance and radiation pattern of a typical antenna with dielectric losses are assessed by the presented scheme. It is verified in comparison with Yee's FDTD.

关键词： frequency-dependnet media Debye model finite-difference time-domain method Newmark-beta method

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Quantifying scattering coefficient for multiple scattering effect by combining optical coherence tomography with finite-difference time-domain simulation method

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JOURNAL OF BIOMEDICAL OPTICS 2018年第8期23卷 086004-086004页

作者： Tsai, Ling-Hsuan Yang, Po Nien Wu, Chung-Chih Lin, Hoang Yan Natl Taiwan Univ Grad Inst Photon & Optoelect Dept Elect Engn Taipei Taiwan Natl Taiwan Univ Grad Inst Elect Engn Dept Elect Engn Taipei Taiwan

In optical coherence tomography (OCT) systems, to precisely obtain the scattering properties of samples is an essential issue in diagnostic applications. Especially with a higher density turbid medium, the light interferes among the adjacent scatters. Combining an OCT experiment with the finite-difference time-domain simulation method, the multiple scattering effect is shown to affect the scattering properties of medium depending on the interparticle spacing. The far-field scattering phase function of scatters with various diameters was simulated to further analyze the corresponding anisotropy factors, which can be introduced into the extended Huygens-Fresnel theory to find the scattering coefficient of measured samples. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE).

关键词： optical coherence tomography multiple scattering effect finite-difference time-domain method extended Huygens-Fresnel theory

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Subwavelength metrology of Al wire grating employing finite difference time domain method and Mueller matrix polarimeter 18

Subwavelength metrology of Al wire grating employing finite ...

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18th Interferometry Conference

作者： Adhikari, Achyut Dev, Kapil Asundi, Anand Nanyang Technol Univ Sch Mech & Aerosp Engn Ctr Opt & Laser Engn 50 Nanyang Ave Singapore 639798 Singapore

ISBN: (数字)9781510603127

ISBN: (纸本)9781510603110;9781510603127

Wire grid polarizers (WGP), are sub-wavelength gratings with applications in display projection system due to their compact size, wide field of view and long-term stability. Measurement and testing of these structures are important to optimize their use. This is done by first measuring the Mueller Matrix of the WGP using a Mueller Matrix Polarimeter. Next the finite difference time domain (FDTD) method is used to simulate a similar Mueller matrix thus providing the period and step height of the WGP. This approach may lead to more generic determination of sub-wavelength structures including diffractive optical structures.

关键词： finite-difference time-domain method Polarization Polarizers Polarimetry Aluminum Polysomnography Metrology Diffraction Glasses Statistical analysis

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Comparison of Electromagnetic Forces Evaluated in Yee-Lattice finite-difference time-domain and Lattice-Boltzmann method

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2022年第12期70卷 12405-12410页

作者： Warner, Cael Markley, Loic Chau, Kenneth J. Univ British Columbia Sch Engn Kelowna BC V1V 1V7 Canada

Electrodynamic simulations in the Yee-lattice finite-difference time-domain method (YL-FDTDM) require half-unit-cell and half-time-unit offsets between electric and magnetic field components. To evaluate energy, momentum, and force in the YL-FDTDM, electric and magnetic fields must be colocated in both space and time. Colocation operations can be computationally intensive while introducing implementation complexity and numerical error. As an alternative to the YL-FDTDM, the Hauser and Verhey electrodynamic lattice-Boltzmann method (HV ELBM) is implemented on a single lattice representing electric and magnetic fields at the same location and time. Since colocation is not required on a single lattice, its central differences are simpler to implement and more accurate. Continuous plane-wave scattering of electric and magnetic fields from a nondispersive dielectric sphere is solved using the YL-FDTDM, the HV ELBM, and Mie scattering analysis. The YL-FDTDM and HV ELBM are compared in terms of numerical error and computational time representing the analytical Mie solution for the Einstein and Laub time-averaged force density. The HV ELBM requires less computational time to evaluate a time-averaged force density with half the error of the YL-FDTDM. At a similar absolute error, the HV ELBM evaluates a time-averaged force density in less than 10% of the computational time.

关键词： finite-difference time-domain method force density lattice-Boltzmann method Mie scattering Yee-lattice (YL)

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Vibration analysis for framed structures using the finite-difference time-domain method based on the Bernoulli-Euler beam theory

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ACOUSTICAL SCIENCE AND TECHNOLOGY 2014年第3期35卷 139-149页

作者： Asakura, Takumi Ishizuka, Takashi Miyajima, Tohru Toyoda, Masahiro Sakamoto, Shinichi Shimizu Corp Inst Technol Koto Ku Tokyo 1358530 Japan Kansai Univ Fac Environm & Urban Engn Suita Osaka 5648680 Japan Univ Tokyo Inst Ind Sci Meguro Ku Tokyo 1538505 Japan

A vibration analysis method for structure-borne sound transmission in framed structures using an implicit finite-difference time-domain (FDTD) method is proposed in this paper. The prediction of structure-borne sound is difficult owing to the complexity of the vibration mechanism in building structures. As a powerful means of analyzing structure-borne sound, wave-based numerical techniques have the potential to solve the problem accurately by virtue of their flexibility from the viewpoint of modeling the object. For this reason, we model the target structure as a composition of beam elements and calculate the characteristics of the wave propagation using the FDTD method. Using the beam model, we can decrease the dimension of the simulated field to one dimension, compared with the situation that the field is discretized by three-dimensional solid elements. This results in a reduction of the computational cost. In this paper, the basic theory of the calculation method for a model with beam elements is described and the results of a case study of a multilayered frame structure are discussed.

关键词： Structure-borne sound finite-difference time-domain method Bernoulli-Euler beam theory Frame model

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On the accuracy of finite-difference time-domain simulations of head-related transfer functions as a function of model complexity

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APPLIED ACOUSTICS 2025年 228卷

作者： Meyer, Julie Prepelita, Sebastian Picinali, Lorenzo Imperial Coll London Dyson Sch Design Engn London SW7 2DB England Meta Real Labs Res Redmond WA 98052 USA

Wave-based numerical tools such as finite-difference time-domain (FDTD) solvers are useful for modeling several acoustic properties and interactions. While these numerical tools are widely used in acoustics, there seems to be less attention to assessing the quality of the produced outputs. However, in order to ensure that the obtained results are reliable, the quantification of the errors present in the simulation results is an essential step. There exists a mathematical process known as solution verification which aims at assessing the accuracy of the computed solutions. A relevant application for the FDTD method is the simulation of head-related transfer functions (HRTFs), since these are relatively complex to acoustically measure on humans. This paper aims at applying the solution verification process on HRTF modeling using the FDTD method to evaluate the accuracy of the simulated HRTF magnitudes with increased human head/torso model complexity. The FDTD-simulated HRTFs are also compared with respect to the similarity/dissimilarity of their spectrum and with respect to the relevance of these spectral variations on sound source localization. The results show that asymptotically extrapolating the FDTD-simulated HRTFs from a series of simulations provides more accurate HRTF predictions when compared to using single FDTD simulations ran on sub-millimeter grids, regardless of the model complexity. Results also demonstrate that the accuracy of the FDTD-simulated HRTF predictions decreases with increased model complexity. The localization performance predictions showed that the largest localization errors were obtained with models with the lowest complexities. Significant differences in predicted sound source localization performance were found between FDTD-simulated results.

关键词： Head-related transfer function Accuracy Solution verification finite-difference time-domain method

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Two-dimensional finite difference-time domain simulation of moving point source array

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JAPANESE JOURNAL OF APPLIED PHYSICS 2025年第3期64卷 03SP19-03SP19页

作者： Tsuchiya, Takao Inoue, Kei Doshisha Univ Dept Informat Syst Design Kyoto 6100321 Japan

In this paper, a moving point source array is theoretically described and implemented in a two-dimensional finite difference-time domain (FDTD) method. The directivity of the moving point source array is theoretically derived by considering phase differences between each source in the two-dimensional field. Then, the moving point source array is implemented in the two-dimensional FDTD method. Numerical experiments were conducted for point source arrays with in-phase driving and phased arrays in the two-dimensional sound field. The FDTD method was confirmed to be able to calculate with less than 1% error up to Mach number 0.4. It was found that the effect of the moving velocity on the directivity increased with increasing source velocity. It was also found that the directivity varies with the direction of sound radiation due to the Doppler effect. The proposed method can be accurately applied to a moving point source array.

关键词： finite-difference time-domain method Doppler effect moving point source array phased array

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