THE RADAR CROSS SECTION OF A SEMI-INFINITE BODY

1960 ◽  
Vol 38 (1) ◽  
pp. 48-56 ◽  
Author(s):  
H. Brysk
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Ad Hoc ◽  
Simultaneous Occurrence ◽  
Body Of Revolution ◽  
Infinite Body ◽  
Incident Plane ◽  
The Cross ◽  
The Difference ◽  
Definition Of

The concept of cross section as applied to a semi-infinite scattering body seems to require some clarification. The need for careful formulation of the problem arises because of the simultaneous occurrence of two characteristic lengths tending to infinity: the range from the radar to the target, and the size of the target. The infinite range assumption in the definition of the cross section allows the incident wave to be approximated as a plane wave in the case of a finite scatterer. For a semi-infinite body, it is customary to retain the plane-wave incidence, and introduce ad hoc arguments to dispose of the awkwardness due to the infinite extent of the scatterer. A return to the basic definition of a cross section, and examination of its motivation, lead here to an unequivocal formulation for the cross section of a semi-infinite body. Its consequences are pursued in the physical optics approximation. In particular, the nose-on backscattering from a body of revolution is exhibited, and results are computed for the paraboloid and the cone (which turn out to agree with the traditional ones). The broadside backscattering from a cylinder is also calculated, and the difference in this case between mono-static backscattering and the return in the backward direction from an incident plane wave is discussed.

Computational Investigation on the Dispersive Transport of Angiographic Contrast Injected Antegradely Into Flow in a Tube

2007 ◽  
Author(s):  
Qing Hao ◽  
Baruch B. Lieber
Keyword(s):  
Coordinate System ◽  
Cross Section ◽  
Single Molecule ◽  
Molecular Diffusion ◽  
Local Concentration ◽  
Dispersive Transport ◽  
Cross Sectional ◽  
Advection Dispersion ◽  
The Cross ◽  
The Difference

When a solute such as angiographic contrast is introduced into a solvent such as blood analog fluid flowing in a straight circular tube, it spreads under the combined action of molecule diffusion and the variation of velocity over the cross-section [8]. If two molecules are being carried in the flow, for example, one in the center and one near the wall, the rate of separation caused by the difference in bulk velocity will greatly exceed that caused by molecule motion. Given enough time, any single molecule would wander randomly throughout the cross section of the pipe because of molecular diffusion, and would sample at random all the advective velocities [4]. Therefore, Taylor [8] adopted the Lagrangian approach to the problem, casting the equations in a coordinate system that moves with the average velocity of the flow and replacing the molecular diffusion coefficient with a dispersion coefficient, and the local concentration with the cross sectional mean concentration. Recasting Taylor’s equation in an inertial coordinate system one obtained the so called advection-dispersion equation.

Secondary Stresses in Airship Hull Structures

1927 ◽  
Vol 31 (204) ◽  
pp. 1073-1109
Author(s):  
J. F. Baker
Keyword(s):  
Cross Section ◽  
External Load ◽  
Structural Engineering ◽  
Secondary Stress ◽  
Rigorous Definition ◽  
The Cross ◽  
Definition Of ◽  
Redundant Structure ◽  
Ball Joints ◽  
External Loads

In no branch of structural engineering is there a rigorous definition of the term “secondary stress.”If the primary stresses in a structure are determined, that is, the stresses in the members due to an external load system, assuming that all the members are joined together by perfect pin- or ball-joints, then the secondary stresses are in general taken to be the additional stresses due to the rigidity of the actual joints used in practice.In such a highly redundant structure as an airship hull the labour involved, in determining even the primary stresses, precludes the use of the normal methods of stressing. It is usual to make use of generalised methods which give approximate results. These generalised methods imply that the external loads are applied to the structure in a certain distribution. Though this is rarely achieved, yet the results obtained are in most cases sufficiently accurate if suitable bracing is supplied to redistribute the external loads over the cross-section; the effect of the initial wrong distribution being then merely local.

A measurement of the cross section for production of He + (2 S ) ions by electron impact excitation of ground state helium ions

1966 ◽  
Vol 290 (1420) ◽  
pp. 74-93 ◽  
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Cross Sections ◽  
Absolute Magnitude ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Close Coupling ◽  
Born Cross Section ◽  
The Absolute ◽  
The Cross

A crossed beams method has been used to measure the cross section for the production of He + (2 S ) by electrons incident upon He + (1 S ) in the energy range from threshold to 750 eV. The cross section was measured in arbitrary units with an accuracy of ± 5 % and at the higher energies its energy dependence is in close agreement with that calculated by means of the plane-wave Born approximation. Consequently the cross section has been normalized to the plane-wave Born cross section at energies between 435 and 750 eV to obtain the absolute magnitude. An independent estimate of the absolute magnitude was made to with in ± 30 % using only the experimental parameters, and the absolute cross sections given by the two methods agree within the experimental uncertainties. The normalized cross section is compared with cross sections given by the close-coupling approximation and various Coulomb-Born approximations. At the lower energies the normalized cross section is considerably smaller than any of the theoretical values, but the measurements are consistent with the existence of a finite cross section at threshold if the energy spread of the electron beam is taken in to account.

City Occupancy and Road Capacity Model

2014 ◽  
Vol 1044-1045 ◽  
pp. 1538-1540 ◽  
Author(s):  
Yi Lin Fan ◽  
Bei Chen Cheng ◽  
Li Li Cao ◽  
Kun Cheng Huang
Keyword(s):  
Cross Section ◽  
Road Traffic ◽  
The Road ◽  
Road Capacity ◽  
Traffic Capacity ◽  
Capacity Model ◽  
The Cross ◽  
Definition Of ◽  
The Impact ◽  
Accident Case

In this paper, we study the impact of city driveway occupancy on the urban road traffic capacity. Through the analysis of the scene of an accident case, we gained the vehicle statistics within a cross section in unit time and then did calculation and simulation. The work is concluded as a reasonable model of vehicle queue relationship evaluation.First, on the base of the definition of traffic capacity, statistics of the cars in the cross section before the accident, during the accident and after the accident have been respectively acquired in unit time (1 min). Then we employ Matlab to do the interpolation fitting, drawing the change of actual capacity of the road from the beginning time of an accident to the time when traffic resumes. The work comes to a conclusion that the change of the capacity at the cross section has a pattern of periodic fluctuation.

scholarly journals Free space transmission lines in receiving antenna operation

2019 ◽  
Author(s):  
Reuven Ianconescu ◽  
Vladimir Vulfin
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Incident Wave ◽  
Transmission Lines ◽  
Incident Plane Wave ◽  
Software Simulation ◽  
Incident Plane ◽  
Receiving Antenna ◽  
Scattering Matrices ◽  
Simulation Results

This work derives exact expressions for the voltage and current induced into a two conductors non isolated transmission lines by an incident plane wave. The methodology is to use the transmission line radiating properties to derive scattering matrices and make use of reciprocity to derive the response to the incident wave. The analysis is in the frequency domain and it considers transmission lines of any small electric cross section, incident by a plane wave from any incident direction and any polarisation. The analytic results are validated by successful comparison with ANSYS commercial software simulation results, and compatible with other published results.

Analysis of Deformation Distribution of Different Points of Hull Cross Section

1989 ◽  
Vol 33 (03) ◽  
pp. 157-161
Author(s):  
Ismail Nassef
Keyword(s):  
Cross Section ◽  
Elastic Theory ◽  
Distribution Effect ◽  
Deformation Distribution ◽  
The Cross ◽  
The Difference

The main objective of this work is to obtain deformations of different points of a hull cross section. Such deformations are impossible to determine using the theory of strength approach. For this purpose, elastic theory methods are applied. The resulting equations have excess terms studying the distribution effect of material of the cross section. An application of the resulting equations is presented with an evaluation of the difference between the traditional and the author's results.

scholarly journals Wγ AND Zγ PRODUCTION AND LIMITS ON ANOMALOUS WWγ, ZZγ AND Zγγ COUPLINGS WITH D0 DETECTOR

2012 ◽  
Vol 27 (14) ◽  
pp. 1230014
Author(s):  
XUEBING BU
Keyword(s):  
Transverse Momentum ◽  
Differential Cross Section ◽  
Cross Section ◽  
Differential Cross ◽  
Final States ◽  
The Cross ◽  
The Difference ◽  
Charged Leptons ◽  
D0 Detector

The recent D0 results on Wγ and Zγ production are presented. First, the cross-section and the difference in rapidities between photons and charged leptons for inclusive W(→lν)+γ production in eγ and μγ final states are discussed, then are the cross-section and differential cross-section as a function of photon transverse momentum for Zγ→l+l-(l = e, μ) process. Finally, I present the limits on anomalous WWγ, ZZγ and Zγγ couplings.

THE RENNER MONOIDS AND CELL DECOMPOSITIONS OF THE SYMPLECTIC ALGEBRAIC MONOIDS

2003 ◽  
Vol 13 (02) ◽  
pp. 111-132 ◽  
Author(s):  
ZHENHENG LI ◽  
LEX E. RENNER
Keyword(s):  
Cross Section ◽  
Borel Subgroup ◽  
Unit Group ◽  
Admissible Sets ◽  
Cell Decompositions ◽  
A Cell ◽  
Direct Definition ◽  
The Cross ◽  
Definition Of ◽  
Renner Monoid

In this paper we explicitly determine the Renner monoid ℛ and the cross section lattice Λ of the symplectic algebraic monoid MSpn in terms of the Weyl group and the concept of admissible sets; it turns out that ℛ is a submonoid of ℛn, the Renner monoid of the whole matrix monoid Mn, and that Λ is a sublattice of Λn, the cross section lattice of Mn. Cell decompositions in algebraic geometry are usually obtained by the method of [1]. We give a more direct definition of cells for MSpn in terms of the B × B-orbits, where B is a Borel subgroup of the unit group G of MSpn. Each cell turns out to be the intersection of MSpn with a cell of Mn. We also show how to obtain these cells using a carefully chosen one parameter subgroup.

scholarly journals An experimental realization of cylindrical cloaking using dogbone metamaterials

2017 ◽  
Vol 95 (10) ◽  
pp. 927-932 ◽  
Author(s):  
V.P. Sarin ◽  
M.P. Jayakrishnan ◽  
P.V. Vinesh ◽  
C.K. Aanandan ◽  
P. Mohanan ◽  
...  
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Research Community ◽  
Experimental Realization ◽  
The Past ◽  
Scattered Power ◽  
Incident Plane ◽  
Effective Reduction ◽  
Target Metal ◽  
Wave Incidence

The quest for invisibility has inspired a deep ardour in the research community over the past decade. The invention of metamaterials has boosted the research on electromagnetic cloaking due to its unusual electromagnetic parameters under plane wave incidence. In this study, we propose a novel cloaking scheme, using dogbone metamaterials, for effectively routing the incident electromagnetic fields around a target metal cylinder under consideration. Notable reduction in the scattered power is observed from the target in comparison to an uncloaked target. Experiments and simulations validate an effective reduction in the scattering cross section of the target and effective guiding of the incident plane wave around the target.

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