Physical Scale Modeling of VHF/UHF SAR Collection Geometries

2004 ◽  
Author(s):  
C. Beaudoin ◽  
A. Gatesman ◽  
M. Clinard ◽  
J. Waldman ◽  
R. Giles ◽  
...  
Keyword(s):  
Scale Modeling ◽  
Physical Scale

Physical Scale Modeling the Millimeter-Wave Backscattering Behavior of Ground Clutter

2001 ◽  
Author(s):  
A. J. Gatesman ◽  
T. M. Goyette ◽  
J. C. Dickinson ◽  
J. Waldman ◽  
J. Neilson ◽  
...  
Keyword(s):  
Millimeter Wave ◽  
Ground Clutter ◽  
Scale Modeling ◽  
Physical Scale

Physical scale modeling the millimeter-wave backscattering behavior of ground clutter

2001 ◽  
Author(s):  
Andrew J. Gatesman ◽  
Thomas M. Goyette ◽  
Jason C. Dickinson ◽  
Jerry Waldman ◽  
Jim Neilson ◽  
...  
Keyword(s):  
Millimeter Wave ◽  
Ground Clutter ◽  
Scale Modeling ◽  
Physical Scale

scholarly journals Development of a Corrosion Potential Measuring System Based on the Generalization of DACS Physical Scale Modeling

2015 ◽  
Vol 34 ◽  
pp. 06005
Author(s):  
Dalei Song ◽  
Xinjian Fan ◽  
Xueyan Ma ◽  
Weiguo Shi ◽  
Xiangdong Wang
Keyword(s):  
Corrosion Potential ◽  
Measuring System ◽  
Scale Modeling ◽  
Physical Scale

Depth sounding by means of a coincident coil frequency‐domain electromagnetic system

Geophysics ◽  
1997 ◽  
Vol 62 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Kenneth Duckworth ◽  
Edward S. Krebes
Keyword(s):  
Frequency Domain ◽  
Half Space ◽  
Free Space ◽  
Thin Sheet ◽  
Electromagnetic System ◽  
Homogeneous Half Space ◽  
Scale Modeling ◽  
Physical Scale ◽  
Depth Sounding ◽  
Theoretical Developments

The concept of electromagnetic depth sounding by means of a coincident‐coil frequency‐domain electromagnetic system is developed in theory and demonstrated by means of physical scale modeling. The concept is based on the use of distance from the target as the sounding variable. The theoretical developments are confined to soundings conducted in free‐space with respect to either a homogeneous half‐space or a thin sheet conductor in conditions that approach the resistive limit. The use of distance from the target as the sounding variable becomes practical when the sounding system is a single compact unit of the type that a coincident coil concept inherently provides. In this method of sounding, the distance from the target is determined by taking the ratios of the fields measured at a variety of distances from the target conductor. This permits not only the distance to the target to be determined but also the direction to that target as may be of interest in soundings conducted in mines.

Main Principles of Vibrodamped Structure Scale Models for the Whole Sound Frequency Range

1995 ◽  
Author(s):  
Alexei V. Ionov
Keyword(s):  
Physical Modelling ◽  
Energy Difference ◽  
Full Scale ◽  
Sound Frequency ◽  
Frequency Range ◽  
Vibration Load ◽  
Scale Modeling ◽  
Physical Scale ◽  
Scale Models ◽  
Dynamic Rigidity

Abstract At low and middle sound frequencies the physical modelling of vibro-absorbing constructions is interpreted as a reconstruction of a frequency dependence of an imaginary part of a full-scale construction dynamic rigidity which is shifted in frequency according to a scale factor. For the high sound frequency range there is a dimensionless form of a matrix energy equation. It allows the task of physical scale modeling to be formulated as a reconstruction of a vibration energy difference between structure elements excited by an external vibration load and the others its elements as in a full-scale object. The analysis is fulfilled in the specially selected frequency bands when the geometrical similarity between scale and full-scale constructions and a number of demands to their material and the loss factors are observed.

Comparison of integral equation and physical scale modeling of the electromagnetic responses of models with large conductivity contrasts

Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. G169-G177 ◽  
Author(s):  
Colin G. Farquharson ◽  
Ken Duckworth ◽  
Douglas W. Oldenburg
Keyword(s):  
Integral Equation ◽  
Electric Field ◽  
Tangential Component ◽  
Basis Functions ◽  
Electromagnetic Modeling ◽  
Equation Solution ◽  
Scale Modeling ◽  
Electromagnetic Responses ◽  
Physical Scale ◽  
A Cell

A comparison is made between the results from two different approaches to modeling geophysical electromagnetic responses: a numerical approach based upon the electric-field integral equation and the physical scale modeling approach. The particular implementation of the integral-equation solution was developed recently, and the comparison presented here is essentially a test of this new formulation. The implementation approximates the region of anomalous conductivity by a mesh of uniform cuboidal cells and approximates the total electric field within a cell by a linear combination of bilinear edge-element basis functions. These basis functions give a representation of the electric field that is divergence free but not curl free within a cell, and whose tangential component is continuous between cells. The charge density (which arises from the discontinuity of the normal com-ponent of the electric field across interfaces between cells of different conductivities and between cells and the background) is incorporated in a similar manner to integral equation solutions to dc resistivity modeling. The scenarios considered for the comparison comprise a graphite cube of [Formula: see text] conductivity and 14-cm length in free space and in brine ([Formula: see text] conductivity). The transmitter and receiver were small horizontal loops; measurements and computations were made for various fixed transmitter-receiver separations and various heights of the transmitter-receiver pair for frequencies ranging from [Formula: see text]. The agreement between the numerical results from the integral-equation implementation and the measurements from the physical scale modeling was very good, contributing to the verification of this particular implementation of the integral-equation solution to electromagnetic modeling.

Evaluation of the Effect of Paint Degradation on Shipboard Impressed Current Cathodic Protection Performance: A Physical Scale Modeling Approach

2009 ◽  
Author(s):  
Yueping Wang ◽  
Ken J. KarisAllen
Keyword(s):  
Numerical Modeling ◽  
Cathodic Protection ◽  
Polarization Resistance ◽  
Current Control ◽  
Aluminum Bronze ◽  
Scale Modeling ◽  
Physical Scale ◽  
Discrete Area ◽  
Impressed Current ◽  
Impressed Current Cathodic Protection

Physical scale modeling (PSM) has been used to evaluate and design shipboard impressed current cathodic protection (ICCP) systems in several NATO countries. With the application of numerical modeling techniques for the evaluation of shipboard ICCP performance, efforts to validate numerical modeling results using PSM data have been gaining increasing importance. As part of the efforts, a discrete area current control (DACC) technique was developed in previous studies to simulate the polarization resistance behavior of multiple cathodes including nickel aluminum bronze propellers and paint damage areas under a variety of conditions. The application of the DACC technique facilitated the use of identical polarization resistance data as boundary conditions for both PSM and numerical modeling analyses in the validation studies. In the current work, the DACC technique was extended to simulating polarization resistance behavior of various paint degradation scenarios (with polarization resistances varying from 1×107 Ωcm2 to 2×105 Ωcm2) to study the effect of paint degradation on the performance of a shipboard ICCP system. The results indicated that overall paint degradation does not significantly affect the hull potential profile until the magnitude of the polarization resistance of the paint coating decreases below 1×107 Ωcm2. The PSM profiles were also compared with numerical modeling data acquired using a boundary element code resulting in a good agreement between the two techniques. The discrepancies observed between the PSM and numerical modeling profiles have also been discussed.

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