A Direct Time-Domain FDTD Near-Field-to-Far-Field Transform in the Presence of an Infinite Grounded Dielectric Slab

2006 ◽  
Vol 54 (12) ◽  
pp. 3805-3814 ◽  
Author(s):  
Ilker R. Capoglu ◽  
Glenn S. Smith
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Far Field ◽  
Dielectric Slab

Average Q and yield estimates from the Pahute Mesa test site

1987 ◽  
Vol 77 (4) ◽  
pp. 1274-1294
Author(s):  
R. W. Burger ◽  
T. Lay ◽  
L. J. Burdick
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Energy Levels ◽  
Source Model ◽  
Spectral Shape ◽  
Field Amplitude ◽  
Far Field ◽  
Source Models ◽  
Attenuation Models ◽  
Shape Data

Abstract Attenuation models, with and without frequency dependence, have been developed through analysis of time-domain amplitude measurements and teleseismic spectral shape data from Pahute Mesa nuclear explosions. The time-domain analysis is based on a near-field to far-field amplitude comparison. The near-field amplitude information is incorporated in two parameterized explosion source models (Mueller-Murphy and Helmberger-Hadley) based on analyses of near-field data. The teleseismic amplitude observations are from a large data set of WWSSN short-period analog recordings. For the narrow-band time-domain data, the various source and attenuation models are indistinguishable. We utilize the spectral shape data in the 0.5- to 4-Hz band as a constraint on the source-attenuation models at higher frequencies, concluding that either source model, when convolved with the appropriate frequency-dependent Q model, can be consistent with both the near-field and far-field time-domain amplitudes and the spectral shape data. Given the trade-off between source and attenuation models and the similarity of the different source models in the 0.5- to 4-Hz band, it is difficult to prefer clearly one source model over the other. The Mueller-Murphy model is more consistent with surface wave amplitude measurements because of larger predicted long-period energy levels. Whether or not frequency dependence is included in the attenuation model, the value of t* near 1 Hz is about 1.0 sec (assuming the Mueller-Murphy source model) or 0.8 sec (assuming the Helmberger-Hadley source model). This 0.2 sec difference results from greater 1-Hz energy levels for the Mueller-Murphy source model. Adopting an average attenuation model, predicted amplitudes and yields are shown to be within the uncertainty of the data for all the events analyzed.

Near-field scanning optical microscopy local luminescence studies of rhodamine dye

Open Physics ◽  
2010 ◽  
Vol 8 (3) ◽  
Author(s):  
Petr Klapetek ◽  
Juraj Bujdák ◽  
Jiří Buršík
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Optical Microscope ◽  
Far Field ◽  
Luminescence Signal ◽  
Local Topography ◽  
Field Radiation ◽  
Scanning Optical Microscopy ◽  
Rhodamine Dye ◽  
Near Field Scanning

AbstractThis article presents results of near-field scanning optical microscope measurement of local luminescence of rhodamine 3B intercalated in montmorillonite samples. We focus on how local topography affects both the excitation and luminescence signals and resulting optical artifacts. The Finite Difference in Time Domain method (FDTD) is used to model the electromagnetic field distribution of the full tip-sample geometry including far-field radiation. Even complex problems like localized luminescence can be simulated computationally using FDTD and these simulations can be used to separate the luminescence signal from topographic artifacts.

Modification to time domain near-field to far-field transformation for FDTD method

1997 ◽  
Vol 33 (25) ◽  
pp. 2132
Author(s):  
A. Giannopoulos ◽  
B.S. Randhawa ◽  
J.M. Tealby ◽  
A.C. Marvin
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Fdtd Method ◽  
Far Field ◽  
Field Transformation

The Attenuation Trend of the Propeller Noise

2013 ◽  
Vol 774-776 ◽  
pp. 82-85
Author(s):  
Chang Run Xiao ◽  
Rui Jie Liu ◽  
Jin Ming Ye
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Dipole Source ◽  
Frequency Noise ◽  
Far Field ◽  
Noise Attenuation ◽  
Blade Surface ◽  
Propeller Noise ◽  
Unsteady Loading ◽  
Blade Frequency

The blade frequency noise of non-cavitation propellers in an non-uniform flow is analyzed in time domain. The unsteady loading (dipole source) on the blade surface is calculated by a potential-based panel method. Through calculation and comparison, the noise attenuation trend of propeller is discussed. The noise decays more quickly in the near field than in the far field. The Attenuation Trend of the Propeller Noise

The Visualization of Electromagnetic Environment for Weapon Equipments

2012 ◽  
Vol 466-467 ◽  
pp. 1191-1196
Author(s):  
Zhong Wei Guo ◽  
Wen Tao Xu ◽  
Hong Feng Li ◽  
Wang Yang Hu
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Near Field ◽  
Far Field ◽  
Electromagnetic Environment ◽  
Electromagnetic Data ◽  
Data Field ◽  
Difference Time

Aiming at the invisibility of the electromagnetic environment (EME), this paper presents the method to visualize the weapon equipments EME. The visualization can be divided into two steps. Firstly, we can model the weapon equipments EME to get the electromagnetic data by the finite difference time domain(FDTD) and the transformation from the near field to the far field. Secondly, we can render the electromagnetic data by the data field visualization. The experiment shows that this way is feasible and effective.

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