scholarly journals An Improved Equivalent Dipole Moment Source Model Based on Regularization Optimization Method for Near Field-Far Field Conversion

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 42504-42518
Author(s):  
Wei Liu ◽  
Zhaowen Yan ◽  
Jianwei Wang ◽  
Zheng Min ◽  
Zhangqiang Ma
Keyword(s):  
Dipole Moment ◽  
Near Field ◽  
Optimization Method ◽  
Source Model ◽  
Far Field ◽  
Model Based ◽  
Equivalent Dipole

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.

Modelling Transport and Dispersion of Effluent Outfalls

1992 ◽  
Vol 25 (9) ◽  
pp. 143-154 ◽  
Author(s):  
A. J. Monteiro ◽  
R. J. Neves ◽  
E. R. Sousa
Keyword(s):  
Velocity Field ◽  
Variable Thickness ◽  
Near Field ◽  
Hydrodynamical Model ◽  
Lagrangian Model ◽  
Far Field ◽  
Initial Thickness ◽  
High Concentration ◽  
Concentration Gradients ◽  
Model Based

The accuracy, applicability and limitations of several kinds of models to simulate the dispersion processes are discussed. An Eulerian-lagrangian model based on the advection of particles is presented. This model is particularly adequate to study plumes with high concentration gradients like those developed by outfall discharges. The model uses the velocity field computed by a 2D depth-integrated hydrodynamical model. The linkage of the near and far field solutions is taken into account using particles of variable thickness. The initial thickness is estimated using an empiric relation for the near field depending on the local discharge conditions. Some results are presented and discussed.

scholarly journals Faulty antenna detection in a linear array using simulated annealing optimization

2020 ◽  
Vol 19 (3) ◽  
pp. 1340
Author(s):  
Navaamsini Boopalan ◽  
Agileswari K. Ramasamy ◽  
Farrukh Hafiz Nagi
Keyword(s):  
Simulated Annealing ◽  
Radiation Pattern ◽  
Antenna Arrays ◽  
Communication Systems ◽  
Linear Array ◽  
Near Field ◽  
Optimization Method ◽  
Random Permutation ◽  
Far Field ◽  
Planar Array

<span lang="EN-US">Sonar, radar and communication systems solely depend on antenna arrays for signal attainment. These arrays are capable of producing directional signals which can be steered in a certain direction. Faulty elements in an array will result in distorted radiation pattern with increased sidelobe levels.  Far-field faulty antenna detection is necessary due to the near field repairing at complex systems like spacecraft. This paper proposes simulated annealing (SA) optimizing method to find the faulty element’s location in a linear array. In this study, a Chebyshev array is presented with the SA optimization method to detect faulty element location with a random permutation of failure locations tested. This method can successfully detect faulty antenna in a linear array. Even though, this method is developed for linear array it can easily be adapted to a planar array.</span>

Magnetic Tag Antenna for UHF Near-field and Far-Field RFID Applications

2015 ◽  
Vol 5 (2) ◽  
pp. 119
Author(s):  
Mondher Dhaouadi ◽  
M. Mabrouk ◽  
T. Vuong ◽  
A. Ghazel
Keyword(s):  
Near Field ◽  
Far Field ◽  
Rfid Applications
Sign in / Sign up

Export Citation Format

Share Document