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Saturday, August 1, 2020 | History

3 edition of Backscatter from a periodic rough surface at near grazing incidence found in the catalog.

Backscatter from a periodic rough surface at near grazing incidence

Backscatter from a periodic rough surface at near grazing incidence

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Published by Ohio State University, National Aeronautics and Space Administration, Langley Research Center, National Technical Information Service, distributor in Columbus, Ohio, Hampton, VA, [Springfield, Va .
Written in English


Edition Notes

StatementA.K. Dominek and H.T. Shamansky
SeriesNASA contractor report -- NASA CR-182397
ContributionsShamansky, H. T, Langley Research Center
The Physical Object
FormatMicroform
Pagination1 v
ID Numbers
Open LibraryOL14972545M

I. Grazing Incidence The first step to achieve surface sensitivity is always to go to grazing incidence scattering geometry: At the critical angle x-ray beams are confined to a penetration depth of about Å, i..e atoms deep in the bulk are not exited by the incident wave. (from the surface of the Earth as well as from other plane-tary bodies) and noncontact surface characterization. Recently the enhancement of scattered light intensity in the backscatter direction from metallic rough surfaces was reported by Mendez and O'Donnell."2 This backscatter peak from other random rough surfaces had been previously.

U.S. Army Public Health Command (USAPHC), Radiation Protection Consultation No. MF-0E7K, Rapiscan Secure Single Pose Dosimetry Study (); 4 and Food and Drug Administration (FDA), Assessment of the Rapiscan Secure Body Scanner for Conformance with Radiological Safety Standards (). 5 The committee briefly describes how it considered radiation measurements from . produces realistic backscatter coefficient values for the scenarios over all incidence angles from normal to grazing. The generator was created using measured data sets reported in the Handbook of Radar Scattering 4. rough 5. very rough 6. high

Backscatter definition is - the scattering of radiation or particles in a direction opposite to that of the incident radiation due to reflection from particles of the medium traversed; also: the radiation or particles so reversed in direction.   19 November Surface scatter effects in grazing incidence x-ray telescopes. James E. Harvey; Patrick L. Thompson; fabrication tolerances frequently dominate both diffraction effects and geometrical aberrations in high resolution grazing incidence x-ray telescopes. The resulting reduction optical performance due to scattering is a strong Cited by: 1.


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Backscatter from a periodic rough surface at near grazing incidence Download PDF EPUB FB2

Get this from a library. Backscatter from a periodic rough surface at near grazing incidence. [Allen K Dominek; H T Shamansky; Langley Research Center.]. The University of Michigan GHz polarimetric radar system was used to perform polarimetric backscatter measurements of the aforementioned road surfaces at.

moisture is less than % near the surface, the co-polarizedbackscattering is reduced from that of dry snow on the order of 5 dB and the cross-polarizedbackscatter is reduced on the order of 10 dB. For the wet snow, with moistures above % to % at the surface, Figure 4 shows that the backscatter varies over a wide range.

Wave Scattering By Periodic Surface At Low Grazing Angles: Two Grazing Mode - Abstract Article (PDF Available) in Journal of Electromagnetic Waves and Applications 14(3) January near-grazing incidence and consider the angular spectrum. We first find the moments of the field at the surface; the accuracy depends upon surface roughness and angle of inci- dence, and diverges for moments of high order.

We then consider the second moment in the medium, which describes. Grazing incidence X-ray and neutron diffraction (GID, GIXD, GIND), typically from a crystalline structure uses small incident angles for the incoming X-ray or neutron beam, so that diffraction can be made surface is used to study surfaces and layers because wave penetration is limited.

Distances are in the order of nanometres. Below (typically 80%) the critical angle of the. a surface scattering model that accounts for multiple scattering up to second order and is expected to be valid for rough surfaces with low to moderate rms slope. Since the volumetric backscatter response is a gentle function of incidence angle, the surface roughness, which causes small variations in the –X/99$ IEEE.

A model for sim~ating the measured radar backscattering coefficient of vegetation-covered soil surfaces is presented in this study. The model consists of two parts: the first is a soft surface model to describe the backscattered radar pulsesCited by: age, periodic, perfectly conducting surface when either the incidence or the scattering grazing angle are small.1 This situation is of significant practical interest for ground-based, active and passive radar studies of the ocean surface, and for long-path propagation along the ocean surface.

Rough surface scattering models used extensively in many practical applications and the analytic conditions for its validity have been investigated in detail in several studies (BECKMANN & SPIZZICHINOCHEN & FUNG ). Small Pertubation Model A perfectly smooth surface has zero backscatter at oblique incidence.

However, in the Bragg. Scattering by Rough Surfaces 15 J. DeSanto Department of Mathematical and Computer Sciences, Colorado School of Mines, Golden, ColoradoU.S.A. Contents w Introduction 15 w Acoustic Scattering 17 w Electromagnetic Scattering 23 w Solution Methods 25 w Inverse Problems 27 w Other Methods and Discussion 28 w by: Additional Effects at Extremely Grazing Incidence.

Doppler = u. wind + u. cur + u. orb + u. break + u. graz + u. rem. Macro shadowing (resolved by the radar) Micro shadowing (smaller than the radar range resolution) • Miret et al. „ the blow-up of the mean Doppler shift at grazing angle is associated to an electromagnetic.

component of the wave vector (normal to the surface or xy-plane) is given by K z = q z 2 = π(sinα i +sinα f) λ, (4) where α i is the grazing angle of incidence. In the specu-lar condition, where the angle of incidence α i is equal to the angle of reflection α f, this is the same as the total wave vector K.

At an interface separating two. The principles of grazing incidence X-ray diffraction (GIXD) are discussed. A sample of a crystalline material is composed of a surface region including its top layer and a bulk part.

The effect of the surface region on the intensity of surface X-ray diffraction cannot be generally by: 7. critical angle is o, for example, any long-range or short-range variation in the surface normal of the order of o will move large parts of the surface out of the total reflection condition.

Second, at grazing angles, most of the incoming X-ray beam is wasted. Assuming an incident angle of o and a surface dimension of 1cm, only a 2Τm slice of.

Surface roughness, radar backscatter, and visible and near‐infrared reflectance in Death Valley, California. Robin J. Weeks. Search for more papers by this author. measurements of surface roughness together with an analysis of the effects of the surface microtopography on radar backscatter and visible and near‐infrared (VNIR Cited by: This paper considers the statistics of a plane wave scattered at low grazing angles from a one‐dimensional rough surface, when the interaction with the surface is mainly in the forward direction.

The mean intensity and autocorrelation of the scattered field and the corresponding angular spectrum, to second order in surface height is by: The intricate nanoscopic morphology of soft materials such as block copolymer and polymer blend system successfully analyzed by small angle X-ray scatterings (SAXS).

In thin films, those soft material systems have attracted great attention because of a potential for practical use of functional materials. The morphology has been revealed by grazing-incidence (GI) by: 2.

The fundamental parameter characterizing surface and volume scattering is the scattering scattering strength, S, is the ratio in dB between the intensity of the sound scattered by a unit surface (1 m 2) or by a unit volume (1 m 3), measured at a distance, 1 m, from the acoustic center of the scattering surface/volume, and the incident acoustic wave : L.

Bjørnø. Lazzari R., Leroy F., Renaud G. Grazing-incidence small-angle X-ray scattering from dense packing of islands on surfaces: Development of distorted wave Born approximation and correlation between particle sizes and spacing; Phys. Rev. B 76, ().Cited by:. With the advent of third-generation synchrotron sources and the development of fast two-dimensional X-ray detectors, X-ray scattering has become an invaluable tool for in-situ time-resolved experiments.

In the case of thin films, grazing incidence small angle X-ray scattering (GISAXS) constitutes a powerful technique to extract morphological information not only of the thin film surface but Cited by: 3.Empirical Sea Backscatter Models for Low Grazing Angles. For surface clutter (sea, land, or ice) the term?

0 is used to represent the normalized mean (or median) reflectivity from an area on the surface of the earth illuminated by a radar. In some references, the term? is used. The value is constant only for a given angle, carrier frequency, sea state, wind direction polarization, and.8-kHz bottom backscattering measurements at low grazing angles (6°–31°) are presented.

The experiment was performed at a very shallow water site with a silty bottom on the south coast of Korea.

Backscattering strengths between −42 and −30 dB were obtained and were compared to a theoretical backscattering model and Lambert’s law. The fit of the theoretical model to the measurements Cited by: