Measuring the backscattering cross section and rate of motion of an object in an inhomogeneous plane layer of plasma having an unknown concentration profile

1975 ◽  
Vol 18 (10) ◽  
pp. 1043-1046
Author(s):  
Yu. M. Zhidko
Keyword(s):  
Cross Section ◽  
Concentration Profile ◽  
Plane Layer ◽  
Backscattering Cross Section ◽  
Inhomogeneous Plane

Backscattering Analysis of Cylinder Shaped Scatterer in Vegetation Medium: Comparison Between Theories

2020 ◽  
Vol 2 (1) ◽  
pp. 15-18
Author(s):  
Syabeela Syahali ◽  
Ewe Hong Tat ◽  
Gobi Vetharatnam ◽  
Li-Jun Jiang ◽  
Hamsalekha A Kumaresan
Keyword(s):  
Numerical Solution ◽  
Cross Section ◽  
Traditional Method ◽  
Microwave Remote Sensing ◽  
Solution Model ◽  
Complex Nature ◽  
Good Match ◽  
Equivalent Source ◽  
Backscattering Cross Section ◽  
Method Model

This paper analyses the backscattering cross section of a cylinder both using traditional method model and a new numerical solution model, namely Relaxed Hierarchical Equivalent Source Algorithm (RHESA). The purpose of this study is to investigate the prospect of incorporating numerical solution model into volume scattering calculation, to be applied into microwave remote sensing in vegetation area. Results show a good match, suggesting that RHESA may be suitable to be used to model the more complex nature of vegetation medium.

Kelvin and V-like Ship Wakes Affected by Surfactants

2001 ◽  
Vol 45 (02) ◽  
pp. 150-163
Author(s):  
Gregory Zilman ◽  
Touvia Miloh
Keyword(s):  
Cross Section ◽  
Single Layer ◽  
Ship Wake ◽  
Backscattering Cross Section ◽  
Alternative Approach ◽  
Ship Wakes ◽  
Half Angle ◽  
Radar Backscattering ◽  
The Green Function ◽  
Theoretical Results

Synthetic aperture radar (SAR) ship wake images in light wind and calm sea conditions frequently appear in the form of a bright V with a half-angle of 2 to 3 deg. Sophisticated and conflicting explanations of this phenomenon, based on the Bragg scattering mechanism, have been proposed. There is a belief that the narrow V-wake is not a part of the Kelvin wake. An alternative approach, which is not generally accepted, suggests that short divergent Kelvin waves may contribute to the V-wake imaging although these waves are mixed with unsteady surface waves generated by the ship-induced turbulence. Ship-generated divergent waves contaminated by surfactants and their radar backscattering cross section are studied. The hull of the ship is represented by a single layer of hydrodynamic singularities. The Green function of a point source moving below a free surface covered by surfactants is derived. A closed-form asymptotic solution for the far ship wave wake is obtained. It is used to calculate analytically the corresponding radar backscattering cross section. The radiative, viscous, and surfactant-induced decay of the V-wake brightness along the V-arms is discussed. The theoretical results are compared against available experimental data.

Effect of Pipe Inclination on Solids Distribution in Partially Stratified Slurry Flow

2019 ◽  
Author(s):  
Václav Matoušek ◽  
Jan Krupička ◽  
Jiří Konfršt ◽  
Pavel Vlasák
Keyword(s):  
Uniform Distribution ◽  
Cross Section ◽  
Inclination Angle ◽  
Concentration Profile ◽  
Stratified Flow ◽  
Concentration Profiles ◽  
Horizontal Pipe ◽  
Pipe Cross Section ◽  
Test Loop ◽  
Pipe Inclination

Abstract Partially stratified flows like flows of sand-water slurries exhibit non-uniform distribution of solids (expressed as a vertical profile of local volumetric concentration) in a pipe cross section. The solids distribution in such flows is sensitive to pipe inclination. The more stratified the flow is the more sensitive its concentration profile is to the pipe slope. In general, the distribution tends to become more uniform (less stratified) if the inclination angle increases from zero (horizontal pipe) to positive values (ascending pipe) up to 90 degree (vertical pipe). In a pipe inclined to negative angles (descending pipe) the development is different. The flow tends to stratify more if it changes from horizontal flow to descending flow down to the angle of about −35 degree. If the angle further decreases towards −90 degree, then the flow becomes less stratified reaching uniform distribution at the vertical position. This also means that the same flow exhibits a very different degree of stratification in ascending and descending pipes inclined to the same (mild) slope say between ±10 and ±40 degree. The rather complex development of the solids distribution with the variation of the inclination of pipe is insufficiently documented experimentally and described theoretically in predictive models for a concentration profile in partially stratified flow. In order to extend the existing limited data set with experimental data for partially stratified flow of medium sand slurry, we have carried out a laboratory experiment with the slurry of narrow graded fraction of sand with the mean grain size of 0.55 mm in our test loop with an invert U-tube inclinable to arbitrary angle between 0 and 90 degree. A pipe of the loop has an internal diameter of 100 mm. Both legs of the U-tube have a measuring section over which differential pressures are measured. Radiometric devices mounted to both measuring sections sense concentration profiles across a pipe cross section. Furthermore, the discharge of slurry is measured in the test loop. In the paper, experimental results are presented for various inclination angles with a small step between 0 and ±45 degree and a development in the shape of the concentration profiles with the changing inclination angle is analyzed. For the analysis, it is critical to distinguish between suspended load and contact load in the flow as the two loads tend to react differently to the flow inclination. The measured concentration profiles and pressure drops are compared with predictions by the layered model adapted for taking the flow inclination into account.

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