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16th International Conference on Ground Penetrating Radar (GPR)

作者： Liu, H. Zhang, Y. X. Long, Z. J. Han, F. Liu, Q. H. Xiamen Univ Inst Electromagnet & Acoust Xiamen 361005 Peoples R China Xiamen Univ Dept Elect Sci Xiamen 361005 Peoples R China Duke Univ Dept Elect & Comp Engn Durham NC 27708 USA

ISBN: (纸本)9781509051816

Compared with a conventional single-channel GPR system, a GPR system with a multi-input and multi output (MEMO) antenna array is not only more efficient in 3D data acquisition, but also allows the collection of a multi-offset dataset, thereby providing additional information for more effective subsurface imaging. We develop a three-dimensional (3-D) reverse time migration (RTM) algorithm for processing MIMO GPR data. The finite-difference time-domain method with a convolutional perfect matching layer boundary is used to simulate the propagation of electromagnetic waves in subsurface dissipative media. The range and lateral resolution of a MIMO GPR system, which works at a stationary mode, is analyzed by numerical experiments. Furthermore, results of laboratory experiments would be presented in the extended abstract.

关键词： GPR system reverse time migration (RTM) finite-difference time-domain method

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A 1-D Propagator for Introduction of Plane Wave to Layered Magnetized Plasma in FDTD method

A 1-D Propagator for Introduction of Plane Wave to Layered M...

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IEEE International Symposium on Antennas and Propagation / USNC-URSI Radio Science Meeting

作者： Zhang, Yang Liu, Yanming Xidian Univ Sch Aerosp Sci & Technol Xian Peoples R China

ISBN: (纸本)9781509028528

In the application of finite-difference time-domain (FDTD) method to wideband plane wave scattering from layered magnetized plasma, it is a challenge to solve the oblique incident plane wave source in 2-D/3-D simulation space. In this work, an efficient 1-D source propagator is proposed for initiation of incident plane wave on the total-field/scattered-field (TF/SF) boundary in layered magnetized plasma in order to introduce plane wave source in the FDTD simulation space. The 1-D source propagator is developed by using of the phase match theory at the medium interface. The characteristics of wideband plane wave scattering from an n-layer magnetized plasma sheath are calculated and the comparisons with exact solutions are given that clearly exhibit the accuracy of the 1-D source propagator.

关键词： finite-difference time-domain method Magnetized plasma stratified structure

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A Novel FDTD Approach for Numerical Dosimetry at a Single Frequency

A Novel FDTD Approach for Numerical Dosimetry at a Single Fr...

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International Symposium on Electromagnetic Compatibility - EMC EUROPE

作者： Chakarothai, Jerdvisanop Wake, Kanako Watanabe, Soichi Natl Inst Informat & Commun Technol NICT Electromagnet Compatibil Lab 4-2-1 Nukui Kitamachi Koganei Tokyo 1848795 Japan

ISBN: (纸本)9781509014163

In this paper, we propose a new approach for finding time-series convergence in a finite-difference time-domain (FDTD) solution at a single frequency. Both amplitude and phase of the FDTD calculation are simultaneously calculated and traced for evaluation of the convergence and for decision of terminating the computation. Validity of the approach has been demonstrated via numerical dosimetry of a homogeneous dielectric sphere in comparison with Mie's analytical results. Induced SAR in a dielectric sphere calculated by using the proposed approach are in good agreement with Mie's results, having differences in the whole-body average SAR for less than 4% at 1 MHz. It has been also demonstrated that the proposed technique is efficient and generally applicable to numerical dosimetry in which only the solution is needed to be determined at a single frequency.

关键词： finite-difference time-domain method single frequency numerical dosimetry steady-state analysis

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Plasmonic Properties of Nanopatterns Fabricated by Nanosphere Shadowing Lithography 13

Plasmonic Properties of Nanopatterns Fabricated by Nanospher...

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Conference on Nanophotonic Materials XIII

作者： Ingram, Whitney He, Yizhuo Zhang, Q. J. Stone, Keenan Ye, Dexian Dennis, William Zhao, Yiping Univ Georgia Dept Phys & Astron Athens GA 30602 USA Shandong Normal Univ Coll Phys & Elect Jinan 250014 Peoples R China Virginia Commonwealth Univ Dept Phys Richmond VA 23284 USA

ISBN: (纸本)9781510602298;9781510602304

The fabrication and optimization of plasmonic nanostructures have many interesting and important applications including advancements in surface-enhanced Raman spectroscopy (SERS). One popular and cost-effective method to fabricate plasmonic nanopatterns is by a colloid template. By combining close-packed colloid monolayer and dynamic shadowing growth, we demonstrate that a variety of nanopatterns, such as nano-triangles, nano-cup triangles, hexagonal holes, and dual triangles, can be fabricated by varying vapor deposition angle, the substrate azimuthal rotation, as well as the evaporation configuration. Especially when a two-source evaporator is used, dual triangles with different shapes and compositions are simultaneously formed. The formation of these nanopatterns can be predicted by numerical and Monte Carlo simulations. In addition, the visible localized surface plasmon resonance (LSPR) of these patterns can be tuned systematically by changing the deposition conditions and the colloidal monolayer. Their plasmonic properties can be understood through finite-difference time-domain simulations. The tunability of LSPR can be used to design optimized substrate for SERS.

关键词： nanosphere lithography localized surface plasmon resonance Monte Carlo simulation colloid monolayers surface enhanced Raman spectroscopy finite-difference time-domain method

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Homogenization of Spatially Dispersive 1D Fractal Metamaterials 10

Homogenization of Spatially Dispersive 1D Fractal Metamateri...

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Conference on Metamaterials X

作者： Moeini, Samaneh Univ Aveiro Dept Eletron Telecomunicacoes & Informat Inst Telecomunicacoes Aveiro Portugal

ISBN: (纸本)9781510601284

A layered uniaxial dielectric structure is considered. The layers in the structure are distributed according to a one-dimensional fractal set. The resulting fractal metamaterial is homogenized with an original source-driven homogenization approach which is suitable for both numerical and analytical calculations. Due to the fact that the considered metamaterial is nonmagnetic, the only effective parameter which needs to be calculated is the effective permittivity dyadic e(ω, k). The effective permittivity is obtained analytically (by using a transfer matrix approach) and numerically (by using a finite-difference time-domain solver).

关键词： Fractal analysis Dielectrics finite-difference time-domain method Electrodes Homogenization Maxwell's equations Metamaterials Electromagnetism Magnetism Microwave radiation Dispersion

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Optical Characterization of Anisotropic Interfaces

Optical Characterization of Anisotropic Interfaces

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作者： Renjie Hou The University of Western Ontario

学位级别：博士

The understanding of optical properties of surfaces and interfaces is critical for the development of new technologies ranging from photonics to molecular electronics. Knowing for example the orientation of molecules functionalized onto a surface yields valuable information about the macroscopic properties of the resulting surface. The optical properties can be tuned using various strategies such as molecular functionalization or patterning of meta-structures that ultimately interact with light in a rational way. Advanced optical and spectroscopy methods allowing one to probe such surfaces are therefore key to correlate properties and surface functionalization. In this thesis, multiple approaches have been taken to understand the optical response of anisotropic interfaces. First, polarization-modulation infrared linear dichroism is used to characterize thin films of azobenzene-containing glasses and follow the dynamic of their orientation. Because of the high charge-transfer of these molecules, their nonlinear properties are also investigated using second harmonic generation microscopy. The coupling of nonlinear active molecules with metallic nanostructures is also investigated using SHG to evaluate the plasmonic enhancements from the nanostructures alone or functionalized with molecules that exhibit high second order hyperpolarizability.

关键词： Anisotropy nonlinear optical measurements localized surface plasmon resonance polarization-modulation infrared spectroscopy second harmonic generation microscopy finite-difference time-domain method gold nanoparticles

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finite-difference time-domain Simulations of Ultrasound Backscattered Waves in Cancellous Bone 5

Finite-Difference Time-Domain Simulations of Ultrasound Back...

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5th International Conference on the Development of Biomedical Engineering in Vietnam

作者： Hosokawa, A. Akashi Natl Coll Technol Dept Elect & Comp Engn Akashi Hyogo Japan

ISBN: (纸本)9783319117768;9783319117751

In this study, using an elastic finite-difference time-domain (FDTD) method with numerical cancellous bone models reconstructed from microcomputed tomographic (mu CT) images of bovine bone, numerical simulations of the backscattered waves in cancellous bone was performed for clarifying the backscatter characteristics. In the simulation model, an ultrasound pulse wave was transmitted toward the front surface of cancellous bone from a circular concave transmitter/receiver in water. Then, two cancellous bone models with different thicknesses, in which an artificial absorbing boundary was set at the back surface opposite to the ultrasound transmission. By calculating the difference between the simulated results of the received signals in the cases of these cancellous bone models, the reflected wave from the front surface could be canceled, and only the backscattered waves inside the bone could be extracted. Using the cancellous bone models with porosities between 0.53 and 0.86 (53% and 86%), which had main trabecular orientation parallel to the thickness direction (or the transmitted ultrasound direction), the peak-to-peak amplitude of the backscattered waves were derived as a function of the porosity. The determination coefficient between the backscattered wave amplitude and the porosity was R-2 = 0.49 (P < 0.001). The correlation was moderate, which was considered to be because the backscattered waves could be affected by not only the porosity but also the trabecular microstructure.

关键词： Cancellous bone Ultrasound backscattered waves Numerical simulation finite-difference time-domain method

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Three-dimensional numerical modeling of fullspace transient electromagnetic responses of water in goaf

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Applied Geophysics 2016年第3期13卷 539-552,581,582页

作者： Chang Jiang-Hao Yu Jing-Cun. Liu Zhi-Xin School of Resources and Geosciences China University of Mining and Technology Xuzhou 221116 China.

The full-space transient electromagnetic response of water-filled goaves in coal mines were numerically modeled. Traditional numerical modeling methods cannot be used to simulate the underground full-space transient electromagnetic field. We used multiple transmitting loops instead of the traditional single transmitting loop to load the transmitting loop into Cartesian grids. We improved the method for calculating the z-component of the magnetic field based on the characteristics of full space. Then, we established the full- space 3D geoelectrical model using geological data for coalmines. In addition, the transient electromagnetic responses of water-filled goaves of variable shape at different locations were simulated by using the finite-difference time-domain （FDTD） method. Moreover, we evaluated the apparent resistivity results. The numerical modeling results suggested that the resistivity differences between the coal seam and its roof and floor greatly affect the distribution of apparent resistivity, resulting in nearly circular contours with the roadway head at the center. The actual distribution of apparent resistivity for different geoelectrical models of water in goaves was consistent with the models. However, when the goal water was located in one side, a false low-resistivity anomaly would appear on the other side owing to the full-space effect but the response was much weaker. Finally, the modeling results were subsequently confirmed by drilling, suggesting that the proposed method was effective.

关键词： Goaf water mine transient electromagnetic method fullspace finite-difference time-domain method

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Modeling and analysis of the temperature sensitivity in two-dimensional photonic crystal microcavity

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JOURNAL OF NANOPHOTONICS 2016年第1期10卷 016007-016007页

作者： Hocini, Abdesselam Harhouz, Ahlam Mohamed Boudiaf Univ Msila Lab Anal Signaux & Syst Dept Elect BP 166Route Ichebilia Msila 28000 Algeria

We propose a temperature sensor design based on the two-dimensional (2-D) photonic crystals (PhCs) microcavity coupled to two waveguides. We consider a Si 2-D PhC, and the refractive index (RI) of distilled water in holes has been taken as temperature dependent. The resonant wavelength will shift when temperature variation induces change in the RIs of the distilled water. The temperature variation causes the shifting of defect modes. The transmission characteristics of light in the sensor under different RIs that correspond to the change in temperatures are simulated by using the finite-difference time-domain method. A sensitivity of 84 pm/degrees C was achieved with the structure proposed. This property can be exploited in the design of a temperature sensor. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： two-dimensional photonic crystal temperature sensor microcavity waveguide finite-difference time-domain method refractive index

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Rayleigh waves, surface disorder, and phonon localization in nanostructures

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Physical Review B 2016年第4期94卷 045312-045312页

作者： L. N. Maurer S. Mei I. Knezevic University of Wisconsin-Madison Madison Wisconsin 53706 USA

We introduce a technique to calculate thermal conductivity in disordered nanostructures: a finite-difference time-domain solution of the elastic-wave equation combined with the Green-Kubo formula. The technique captures phonon wave behavior and scales well to nanostructures that are too large or too surface disordered to simulate with many other techniques. We investigate the role of Rayleigh waves and surface disorder on thermal transport by studying graphenelike nanoribbons with free edges (allowing Rayleigh waves) and fixed edges (prohibiting Rayleigh waves). We find that free edges result in a significantly lower thermal conductivity than fixed ones. Free edges both introduce Rayleigh waves and cause all low-frequency modes (bulk and surface) to become more localized. Increasing surface disorder on free edges draws energy away from the center of the ribbon and toward the disordered edges, where it gets trapped in localized surface modes. These effects are not seen in ribbons with fixed boundary conditions and illustrate the importance of phonon-surface modes in nanostructures.

关键词： Localization Phonons Thermal conductivity Nanostructures finite-difference time-domain method

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