On: “Special Report of the Subcommittee on Polarity Standards” by Ben B. Thigpen, A. E. Dalby, and Ralph Landrum (GEOPHYSICS, August 1975, p. 694–699)

Geophysics ◽  
1976 ◽  
Vol 41 (2) ◽  
pp. 324-324
Author(s):  
W. T. Valenta
Keyword(s):  
Reflection Coefficient ◽  
Compressional Wave ◽  
Velocity Versus ◽  
Reflection Coefficients ◽  
Special Report ◽  
Sonic Logs ◽  
The Relationship

In their report, the authors recommend that the arrival of a compressional wave at a geophone or hydrophone shall ultimately produce a trough (downward or leftward kick) on a seismogram; but they don’t say why. On sonic logs and displays of velocity versus time, velocity increases are up; likewise for density increases on density logs; likewise for positive reflection coefficients on reflection coefficient logs computed from the previously mentioned logs. Should not seismograms, which ideally are bandlimited reflection coefficient logs, conform to the same convention? The committee succeeded in the objectives of establishing the relationship between impulse‐source systems and vibratory‐source systems and of establishing tests for the determination of the polarity of a given system. I feel strongly that the committee should recommend that a compressional arrival shall produce a peak on a seismogram.

The influence of reflection coefficient statistics on the seismic method: scattering attenuation and transmission wavelets

1992 ◽  
Vol 439 (1905) ◽  
pp. 1-23 ◽  
Keyword(s):  
Reflection Coefficient ◽  
Seismic Energy ◽  
Reflection Coefficients ◽  
Mean Square ◽  
Statistical Parameters ◽  
Seismic Surveys ◽  
Reflection Seismic ◽  
Starting Point ◽  
Sonic Logs ◽  
Scattered Component

The propagation through layered media of seismic energy from reflection seismic surveys is discussed in terms of one dimensional elastic scattering. The effect of a layered overburden on the detectability of the underlying target horizons is investigated. The required signal from the target reflectors arises from the two-way forward-scattered component whereas the internal multiple noise (which tends to obscure the target reflections) arises from the back-scattered component. The starting point of the investigation is the O’Doherty-Anstey relation for the two-way transmission response. In this paper, using statistical models of real reflection series, we derive Q -like attenuation laws for the two-way transmission. Most real sequences of reflection coefficients have spectra which rise with frequency in the seismic band and this leads to signal attenuation which only approximates to that of a 'constant Q ’ type over small bands of frequency. The implications of the theory are checked for two very different types of overburden, one being a repetitive type of sedimentary sequence with a large mean square reflection coefficient and the other a non-repetitive sequence with a small mean square reflection coefficient, against synthetic seismograms derived from real sonic logs. The minimum phase wavelet predicted by the theory is shown to model adequately the first pulse of the two-way transmission waveform, carrying the greater part of the energy, and the lag of the first peak is given approximately in terms of the statistical parameters of the reflection coefficients in the overburden.

scholarly journals Influence of water content of expanded clay on the reflection coefficient of electromagnetic shild

2021 ◽  
Vol 66 (1) ◽  
pp. 93-100
Author(s):  
T. V. Borbot’ko ◽  
S. E. Savanovich
Keyword(s):  
Reflection Coefficient ◽  
Moisture Content ◽  
Electromagnetic Radiation ◽  
Pore Size ◽  
Operating Frequency ◽  
Reflection Coefficients ◽  
Frequency Range ◽  
Operating Frequency Range ◽  
Influence Of Water ◽  
The Relationship

The regularities of the influence of the moisture content of expanded clay on the values of the reflection coefficient of electromagnetic radiation (EMR) of this material in the frequency range of 1–17 GHz have been established. The relationship between the size of fractions (pore size) of expanded clay and the operating frequency range of the EMR screen samples has been determined. It is shown that a twofold increase in the moisture content of expanded clay with fractions of 1…4 and 10…20 mm provides an extension of the operating frequency range of the EMR shield samples made on the basis of this material, with a decrease in the reflection coefficient of the test samples by 1.7 and 3 times, respectively. It was found that an increase in the moisture content of expanded clay from 19 to 40 % with a decrease in the size of its fractions from 10…20 to 1…4 mm and a pore size from 0.1…0.2 to 0.01…0.06 mm provides a decrease in the values of the reflection coefficient of EMR screen samples at frequencies of 7.7–17.0 GHz, and an increase in the size of expanded clay fractions from 1…4 to 10…20 mm with an increase in the size of its pores from 0.01…0.06 to 0.1…0.2 mm provides a decrease in the values of the reflection coefficient of EMR screen samples at frequencies of 1.0–7.7 GHz. It is shown that the practical use of these regularities makes it possible to form EMR screen samples with reflection coefficients from –2.8 to –22.0 dB in the frequency range 1–17 GHz, which makes it possible to recommend them for use when creating shielded rooms.

scholarly journals Second-Order Approximation of the Seismic Reflection Coefficient in Thin Interbeds

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1465 ◽  
Author(s):  
Zhen Yang ◽  
Jun Lu
Keyword(s):  
Theoretical Model ◽  
Reflection Coefficient ◽  
Seismic Reflection ◽  
Transmission Loss ◽  
Order Approximation ◽  
Compressional Wave ◽  
Second Order ◽  
Reflection Coefficients ◽  
Second Order Approximation ◽  
Approximate Equations

As most of the lithostratigraphic reservoirs in China are thin interbeds, the study of seismic responses in thin interbeds is an integral part of lithologic reservoir exploration. However, at present, the research on seismic reflection coefficients of thin interbeds in exploration seismology is still weak, which leads to the lack of theoretical basis for the subsequent interpretation of amplitude variation with offset (AVO) related to thin interbed. To solve this problem, in this paper, we proposed second-order approximate equations of the seismic reflection coefficients in thin-bed and thin-interbed layers. Under the assumption of a small impedance contrast in layered media, we made a second-order approximation with a more evident physical meaning to the reflection coefficient calculation method proposed by Kennett. Then, based on the test of the single thin-layer theoretical model, it was confirmed that the second-order approximation equation of the PP-wave (reflected compressional wave) is accurate at incident angles less than 30°, and that of the PS-wave (converted shear wave) is accurate at wider incident angles. Finally, based on the single-thin-bed equations, the approximate equations of seismic reflection coefficients in thin interbeds were established, the validity of which was verified by the theoretical model. Our equations will be applicable to the calculation of PP- and PS-wave reflection coefficients in thin interbeds where internal multiples are difficult to suppress and transmission loss is hard to accurately compensate. This lays a theoretical foundation for improving the seismic prediction accuracy of lithologic reservoirs.

scholarly journals Determination of dielectric permeability of substances by electromagnetic waveguide method

2020 ◽  
Vol 28 (1) ◽  
pp. 85-90
Author(s):  
Vikt. V. Ovsyanikov ◽  
E. R. Beznosova ◽  
L. Z. Tsypko ◽  
L. I. Filins’kyy ◽  
Vl. V. Ovsyanikov
Keyword(s):  
Dielectric Constant ◽  
Reflection Coefficient ◽  
Complex Permittivity ◽  
Dielectric Permeability ◽  
Microwave Range ◽  
Electromagnetic Waveguide ◽  
The Relationship ◽  
Waveguide Method

A method for determining the complex permittivity of substances by the electromagnetic (EM) waveguide method in the microwave range using electrodynamics and the theory of multilayer dielectric structures is considered. The expression for the complex reflection coefficient of an EM wave in a waveguide with a substance sample is studied. Calculations of the dielectric constant of substances are carried out by analytical and numerical methods using computers. To obtain the desired complex permittivity of a substance, we use the relationship between the expression for the reflection coefficient modulus and the value of the standing wave coefficient over voltage measured in advance in the frequency range. The method is suitable for automation and application in enterprises producing and using fuels, construction and agricultural products. From the found value of the dielectric constant, the quality of substances can be determined. For example, the results of determining the dielectric constant several coals and solid-state foam are given.

When reflection coefficients are zero

Geophysics ◽  
1986 ◽  
Vol 51 (3) ◽  
pp. 736-741 ◽  
Author(s):  
F. K. Levin
Keyword(s):  
Reflection Coefficient ◽  
Shear Wave ◽  
Incidence Angle ◽  
Compressional Wave ◽  
Plane Interface ◽  
Reflection Coefficients ◽  
Wave Velocities ◽  
Shear Wave Velocities

At certain angles of incidence, the amplitude of a plane compressional wave reflected from a plane interface separating two solids is zero. Here I consider as a function of incidence angle those combinations of densities, compressional‐wave velocities, and shear‐wave velocities that give rise to a vanishing reflection coefficient.

Comparison of protein lymph flux and extravascular uptake in skin during increased venous pressure

1992 ◽  
Vol 263 (3) ◽  
pp. H895-H902 ◽  
Author(s):  
J. R. Wallace ◽  
D. R. Bell
Keyword(s):  
Reflection Coefficient ◽  
Immunoglobulin G ◽  
Venous Pressure ◽  
Lymph Flow ◽  
Reflection Coefficients ◽  
The Relationship

The hypothesis that the albumin reflection coefficient is underestimated from measurements of lymph protein flux because of a prolonged interstitial washout was tested in the hindleg of anesthetized rabbits. In heel skin, the initial extravascular uptake for labeled albumin and immunoglobulin G (IgG) was compared with prenodal lymph flux for native albumin and IgG. Venous pressure was increased in one leg for 4 h, while the contralateral leg was the control. The extravascular uptake for labeled albumin was 67% greater than control during the fourth hour of increased venous pressure. Lymph albumin flux was 2.3 times control, indicating a small but significant washout of interstitial albumin. The magnitude of the interstitial washout for IgG was less than that for albumin. Using the relationship between the change in extravascular uptake and the change in lymph flow, the reflection coefficients for albumin and IgG were both 0.91. The reflection coefficient for albumin using lymph protein flux was lower because of a continued interstitial washout.

Thromboplastin Related Differences in the Determination of International Normalised Ratio: A Cause for Concern?

1994 ◽  
Vol 72 (03) ◽  
pp. 426-429 ◽  
Author(s):  
S Kitchen ◽  
I D Walker ◽  
T A L Woods ◽  
F E Preston
Keyword(s):  
Patient Management ◽  
External Quality Assessment ◽  
Oral Anticoagulant Therapy ◽  
Warfarin Dosage ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
International Normalised Ratio ◽  
The Uk ◽  
The Relationship

SummaryWhen the International Normalised Ratio (INR) is used for control of oral anticoagulant therapy the same result should be obtained irrespective of the laboratory reagent used. However, in the UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation INRs determined using different reagents have been significantly different.For 18 NEQAS samples Manchester Reagent (MR) was associated with significantly lower INRs than those obtained using Diagen Activated (DA, p = 0.0004) or Instrumentation Laboratory PT-Fib HS (IL, p = 0.0001). Mean INRs for this group were 3.15, 3.61, and 3.65 for MR, DA, and IL respectively. For 61 fresh samples from warfarin-ised patients with INRs of greater than 3.0 the relationship between thromboplastins in respect of INR was similar to that observed for NEQAS data. Thus INRs obtained with MR were significantly lower than with DA or IL (p <0.0001). Mean INRs for this group were 4.01, 4.40, and 4.59 for MR, DA, and IL respectively.We conclude that the differences between INRs measured with the thromboplastins studied here are sufficiently great to influence patient management through warfarin dosage schedules, particularly in the upper therapeutic range of INR. There is clearly a need to address the issues responsible for the observed discrepancies.

Modern determinants of endometrium hyperplastic processes pathogenesis

2016 ◽  
pp. 137-142
Author(s):  
V.O. Benyuk ◽  
◽  
V.M. Goncharenko ◽  
T.R. Nykoniuk ◽  
◽  
...  
Keyword(s):  
Conservative Therapy ◽  
Solid Phase ◽  
Research Direction ◽  
Immunohistochemical Method ◽  
Results Of Treatment ◽  
Treatment And Prevention ◽  
Receptor Phenotype ◽  
The Relationship ◽  
Endometrial Proliferation

The objective: to еxplore the relationship between the activity of endometrial proliferation and the state of the local immune response in the uterus in the conditions berprestasi process. Patients and methods. Examined 228 women of reproductive and perimenopausal age with endometrial pathology using ultrasound and then performing hysteroresectoscopy. Determination of the concentrations of the cytokines IL-1, IL-2, IL-6 and TNF was performed by solid phase ELISA. Results. Found a trend that confirms the loss of sensitivity to hormones at the stage of malignancy of the endometrium and can be used as diagnostic determinants in determining the nature of intrauterine pathology and criterion of the effectiveness of conservative therapy. Conclusion. Improving etiopatogenetice approach to the therapy of hyperplastic proce.sses of endometrium with determination of receptor phenotype of the endometrium is a research direction in modern gynecology, which will help to improve the results of treatment and prevention of intrauterine pathology. Key words: endometrial hyperplasia,the receptors for progesterone and estrogen, immunohistochemical method.

Calculating the aerodynamics of vertical axis wind turbines

2012 ◽  
Vol 34 (3) ◽  
pp. 169-184 ◽  
Author(s):  
Hoang Thi Bich Ngoc
Keyword(s):  
Wind Turbine ◽  
Incidence Angle ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Velocity Triangle ◽  
Relationship Of ◽  
The Relationship

Vertical axis wind turbine technology has been applied last years, very long after horizontal axis wind turbine technology. Aerodynamic problems of vertical axis wind machines are discussible. An important problem is the determination of the incidence law in the interaction between wind and rotor blades. The focus of the work is to establish equations of the incidence depending on the blade azimuth, and to solve them. From these results, aerodynamic torques and power can be calculated. The incidence angle is a parameter of velocity triangle, and both the factors depend not only on the blade azimuth but also on the ratio of rotational speed and horizontal speed. The built computational program allows theoretically selecting the relationship of geometric parameters of wind turbine in accordance with requirements on power, wind speed and installation conditions.

Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part I: Introduction and Details on the Organization of the Program

1986 ◽  
Vol 14 (4) ◽  
pp. 201-218 ◽  
Author(s):  
A. G. Veith
Keyword(s):  
Aspect Ratio ◽  
Comprehensive Evaluation ◽  
Test Method ◽  
Interactive Effects ◽  
Data Analyses ◽  
Main Effect ◽  
Systematic Determination ◽  
Relationship Of ◽  
The Relationship

Abstract This four-part series of papers addresses the problem of systematic determination of the influence of several tire factors on tire treadwear. Both the main effect of each factor and some of their interactive effects are included. The program was also structured to evaluate the influence of some external-to-tire conditions on the relationship of tire factors to treadwear. Part I describes the experimental design used to evaluate the effects on treadwear of generic tire type, aspect ratio, tread pattern (groove or void level), type of pattern (straight rib or block), and tread compound. Construction procedures and precautions used to obtain a valid and functional test method are included. Two guiding principles to be used in the data analyses of Parts II and III are discussed. These are the fractional groove and void concept, to characterize tread pattern geometry, and a demonstration of the equivalence of wear rate for identical compounds on whole tread or multi-section tread tires.

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