Absolute measurements of small specular reflection coefficients

1987 ◽  
Vol 30 (3) ◽  
pp. 218-220 ◽  
Author(s):  
M. A. Bukhshtab
Keyword(s):  
Specular Reflection ◽  
Reflection Coefficients ◽  
Absolute Measurements

Multiple weights in diffraction stack migration

Geophysics ◽  
1993 ◽  
Vol 58 (12) ◽  
pp. 1820-1830 ◽  
Author(s):  
M. Tygel ◽  
J. Schleicher ◽  
P. Hubral ◽  
C. Hanitzsch
Keyword(s):  
Ray Tracing ◽  
Seismic Data ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Weight Vector ◽  
Reflection Coefficients ◽  
Dynamic Information ◽  
Data Set ◽  
Kirchhoff Migration ◽  
Multiple Weights

Three‐dimensional (3-D) prestack diffraction‐stack migration methods (often called Kirchhoff migration/inversion) play a fundamental role in seismic imaging. In addition to estimating the location of arbitrarily curved reflectors and the angle‐dependent reflection coefficients upon them, they can also be used to provide useful kinematic and dynamic information about the specular reflection ray that connects the source and receiver via the unknown reflecting interface. This is achieved by performing a diffraction stack more than once upon the same seismic data set using identical stacking surfaces but different weights. Some of these weights can be applied simultaneously, i.e., as a weight‐vector. The approach offers the possibility of determining various useful quantities that help to compute and interpret migrated reflections. The vector‐weighted diffraction stack is principally intended to economize the amplitude‐preserving migration that normally would require a large amount of dynamic ray tracing. A simple 2-D synthetic example shows how the method works in principle.

scholarly journals Wave structure at radar irradiation of homogeneous absorbing media

2021 ◽  
Vol 2140 (1) ◽  
pp. 012020
Author(s):  
V P Butukhanov ◽  
Ju L Lomukhin ◽  
E B Atutov
Keyword(s):  
Field Strength ◽  
Plane Wave ◽  
Electric Field ◽  
Specular Reflection ◽  
Wave Structure ◽  
The Other ◽  
Reflection Coefficients ◽  
Propagating Waves ◽  
The Media ◽  
Absorbing Media

Abstract The work is devoted to the study of the structure of waves excited in bordering media under radar irradiation of both smooth and rough interfaces. It is found that counter propagating waves are excited in bordering absorbing media, which determine backward reflection at the interface. On the other hand, the reflection of the counter propagating wave excites waves with a negative angle of refraction. It was found in this work that when the interface is irradiated with a plane wave during polarization, when the electric field strength vector lies in the plane of incidence, the backward reflection and the refracted wave are increases, and the specular reflection decreases. Electrodynamics models of the back reflection coefficients are developed for both the case of smooth and for the case of uneven interfaces between the media.

Applicability of the existing procedure for measuring the specular reflection coefficients of millimeter radio waves under strong refraction conditions

1984 ◽  
Vol 27 (10) ◽  
pp. 853-855
Author(s):  
L. M. Lobkova ◽  
N. I. Mishareva ◽  
V. V. Stel'makh ◽  
Yu. P. Mikhailyuk ◽  
A. I. Nadobenko ◽  
...  
Keyword(s):  
Specular Reflection ◽  
Reflection Coefficients ◽  
Radio Waves

Forensic applications of IR infrared microscopic internal reflection spectroscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1528-1529
Author(s):  
Edward G. Bartick ◽  
John A. Reffner
Keyword(s):  
Specular Reflection ◽  
Forensic Analysis ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Standard Size ◽  
Ir Microscopy ◽  
Ir Analysis ◽  
Plastic Explosives ◽  
Internal Reflection Spectroscopy ◽  
Reflectance Measurements

Since the introduction of commercial Fourier transform infrared (FTIR) microscopic systems in 1983, IR microscopy has developed as an important analytical tool in research, industry and forensic analysis. Because of the frequent encounter of small quantities of physical evidence found at crime scenes, spectroscopic IR microscopes have proven particularly valuable for forensic applications. Transmittance and reflectance measurements have proven very useful. Reflection-absorption, specular reflection, and diffuse reflection have all been applied. However, it has been only very recently that an internal reflection (IRS) objective has been commercially introduced.The IRS method, also known as attenuated total reflection (ATR), has proven very useful for IR analysis of standard size samples. The method has been applied to adhesive tapes, plastic explosives, and general applications in the analysis of opaque materials found as evidence. The small quantities or uncontaminated areas of specimens frequently found requiring forensic analysis will often be directly applicable to microscopic IRS analysis.

Valence electron energy loss spectroscopy in reflection geometry

1989 ◽  
Vol 47 ◽  
pp. 378-379
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Energy Loss ◽  
Valence Electron ◽  
Interband Transition ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Electron Excitation ◽  
Transmission Electron ◽  
Yield Information ◽  
Valence Bands ◽  
Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

Validation of a bioelectrical impedance scale for the estimation of body fat in adolescents

2020 ◽  
Vol 19 (5) ◽  
pp. 369
Author(s):  
Andreia Pelegrini ◽  
André De Araújo Pinto ◽  
Hector Cris Colares De Angelo ◽  
Gaia Salvador Claumann ◽  
Diego Augusto Santos Silva ◽  
...  
Keyword(s):  
Body Fat ◽  
Bioelectrical Impedance ◽  
Air Displacement Plethysmography ◽  
Overweight Adolescents ◽  
The Absolute ◽  
Absolute Measurements

Several different instruments available on the market have been used for the estimation of body fat. However, many of these instruments have not been compared with reference criteria to verify their true accuracy. This study aimed to verify the validity of a bioelectrical impedance scale (OMRON-514C) for the estimation of body fat. Forty-four overweight adolescents (25 females) participated in this study, with an average age of 12.3 ± 1.1 years. All were submitted to body fat evaluations by air displacement plethysmography and bioelectrical impedance. Higher values of relative and absolute body fat were estimated by bioelectrical impedance compared to plethysmography (p < 0.05). There was no correlation between the relative body fat measurements between the two methods (r = 0.185; p = 0.228). The absolute measurements of body fat were correlated (r = 0.497, p = 0.001). Both in the measurements of relative (p= 0.034) and absolute body fat (p = 0.021), the bioelectrical impedance overestimated the measured values. Thus, in adolescents with characteristics similar to the present study, the estimate of body fat by the bioelectrical impedance (OMRON-514C) should be used with caution.Keywords: plethysmography, bioelectrical impedance, adolescents, overweight.

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