On: “A sum autoregressive formula for the reflection response” by P. Hubral, S. Treitel, and P. R. Gutowski (GEOPHYSICS, November 1980, p. 1697–1705).

Geophysics ◽  
1983 ◽  
Vol 48 (3) ◽  
pp. 400-401
Author(s):  
Edward Szaraniec
Keyword(s):  
Layered System ◽  
Multiple Reflections

The paper deals with the decomposition of the impulsive reflection seismogram into progressively delayed generalized primary wavelets. This decomposition serves to examine the patterns of primary and multiple reflections arising from the addition of a deeper interface to the layered system. Each of the generalized primary wavelets originates from a layered system augmented by a single deeper layer.

On unified dual fields and Einstein deconvolution

Geophysics ◽  
2000 ◽  
Vol 65 (1) ◽  
pp. 293-303 ◽  
Author(s):  
Dan Loewenthal ◽  
Enders A. Robinson
Keyword(s):  
Particle Velocity ◽  
Albert Einstein ◽  
Interface Condition ◽  
Layered System ◽  
Multiple Reflections ◽  
Time And Space ◽  
Velocity Signal ◽  
Unit Impulse ◽  
Physical Phenomena ◽  
Receiver Point

In many physical phenomena, the laws governing motion can be looked at as the relationship between unified dual fields which are continuous in time and space. Both fields are activated by a single source. The most notable example of such phenomena is electromagnetism, in which the dual fields are the electric field and the magnetic field. Another example is acoustics, in which the dual fields are the particle‐velocity field and the pressure field. The two fields are activated by the same source and satisfy two first‐order partial differential equations, such as those obtained by Newton’s laws or Maxwell’s equations. These equations are symmetrical in time and space, i.e., they obey the same wave equation, which differs only in the interface condition changing sign. The generalization of the Einstein velocity addition equation to a layered system explains how multiple reflections are generated. This result shows how dual sensors at a receiver point at depth provide the information required for a new deconvolution method. This method is called Einstein deconvolution in honor of Albert Einstein. Einstein deconvolution requires measurements of the pressure signal, the particle velocity signal, and the rock impedance, all at the receiver point. From these measurements, the downgoing and upgoing waves at the receiver are computed. Einstein deconvolution is the process of deconvolving the upgoing wave by the downgoing wave. Knowledge of the source signature is not required. Einstein deconvolution removes the unknown source signature and strips off the effects of all the layers above the receiver point. Specifically, the output of Einstein deconvolution is the unit‐impulse reflection response of the layers below the receiver point. Compared with the field data, the unit‐impulse reflection response gives a much clearer picture of the deep horizons, a desirable result in all remote detection problems. In addition, the unit‐impulse reflection response is precisely the input required to perform dynamic deconvolution. Dynamic deconvolution yields the reflectivity (i.e., reflection‐ coefficient series) of the interfaces below the receiver point. Alternatively, predictive deconvolution can be used instead of dynamic deconvolution.

A sum autoregressive formula for the reflection response

Geophysics ◽  
1980 ◽  
Vol 45 (11) ◽  
pp. 1697-1705 ◽  
Author(s):  
Peter Hubral ◽  
Sven Treitel ◽  
Paul R. Gutowski
Keyword(s):  
Moving Average ◽  
Arma Model ◽  
Normal Incidence ◽  
Simple Relation ◽  
Stratified Medium ◽  
Autoregressive Moving Average ◽  
Layered System ◽  
Multiple Reflections ◽  
Leading Term ◽  
Minimum Delay

The normal incidence unit impulse reflection response of a perfectly stratified medium is expressible as an autoregressive‐moving average (ARMA) model. In this representation, the autoregressive (AR) component describes the multiple patterns generated within the medium. The moving average (MA) component, on the other hand, bears a simple relation to the sequence of reflection coefficients (i.e., primaries only) of the layered structure. An alternate representation of the reflection response can be formulated in terms of a superposition of purely AR time‐varying minimum‐delay wavelets. Each successive addition of a deeper interface to the layered system gives rise to an AR wavelet whose leading term is equal to the magnitude of the primary reflection originating at this interface. We accordingly call these wavelets “generalized primaries.” The AR component of every generalized primary contains only those multiple reflections that arise from the addition of its particular interface to the layered medium.

The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

2020 ◽  
pp. 108-115 ◽  
Author(s):  
Vladimir P. Budak ◽  
Anton V. Grimaylo
Keyword(s):  
Mathematical Model ◽  
Light Field ◽  
Global Illumination ◽  
Multiple Reflections ◽  
Software Environment ◽  
The Monte Carlo Method ◽  
Mueller Matrices ◽  
Volume Integration ◽  
The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

Recovering waste energy of the combined gas turbine system using paraffin melting

2020 ◽  
Vol 14 (4) ◽  
pp. 7481-7497
Author(s):  
Yousef Najjar ◽  
Abdelrahman Irbai
Keyword(s):  
Melting Process ◽  
Payback Period ◽  
Energy Utilization ◽  
Raw Material ◽  
Heat Transfer Fluid ◽  
Layered System ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Power Cycle ◽  
Waste Energy

This work covers waste energy utilization of the combined power cycle by using it in the candle raw material (paraffin) melting process and an economic study for this process. After a partial utilization of the burned fuel energy in a real bottoming steam power generation, the exhaust gas contains 0.033 of the initially burned energy. This tail energy with about 128 ºC is partly driven in the heat exchanger of the paraffin melting system. Ansys-Fluent Software was used to study the paraffin wax melting process by using a layered system that utilizes an increased interface area between the heat transfer fluid (HTF) and the phase change material (PCM) to improve the paraffin melting process. The results indicate that using 47.35 kg/s, which is 5% of the entire exhaust gas (881.33 kg/s) from the exit of the combined power cycle, would be enough for producing 1100 tons per month, which corresponds to the production quantity by real candle's factories. Also, 63% of the LPG cost will be saved, and the payback period of the melting system is 2.4 years. Moreover, as the exhaust gas temperature increases, the consumed power and the payback period will decrease.

Microwave Non-Destructive Testing of Coatings and Paints Using Free Space Microwave Measurement

2005 ◽  
Vol 2 (2) ◽  
pp. 17
Author(s):  
Norhayati Hamzah ◽  
Deepak Kumar Ghodgaonkar ◽  
Kamal Faizin Che Kasim ◽  
Zaiki Awang
Keyword(s):  
Free Space ◽  
Protective Coatings ◽  
Microwave Measurement ◽  
Multiple Reflections ◽  
Destructive Testing ◽  
Lens Antennas ◽  
Coatings And Paints ◽  
Microwave Nondestructive Testing ◽  
Mode Transitions ◽  
Diffraction Effects

Microwave nondestructive testing (MNDT) techniques are applied to evaluate quality of anti-corrosive protective coatings and paints on metal surfaces. A tree-space microwave measurement (FSMM) system is used for MNDT of protective coatings. The FSMM system consists of transmit and receive spot-focusing horn lens antennas, a vector network analyzer, mode transitions and a computer. Diffraction effects at the edges of the sample are minimized by using spot-focusing horn lens antennas. Errors due to multiple reflections between antennas are corrected by using free-space LRL (line, reflect, line) calibration technique. We have measured complex reflection coefficient of polyurethane based paint which is coated on brass plates.

Reflection on Learner-Led Study Abroad Events in a SAC from Three Perspectives: A Learner, an Administrative Staff Member, and an Advisor

Relay Journal ◽  
2020 ◽  
pp. 66-79
Author(s):  
Mizuki Shibata ◽  
Chihiro Hayashi ◽  
Yuri Imamura
Keyword(s):  
Study Abroad ◽  
Language Learning ◽  
Support System ◽  
Staff Member ◽  
Administrative Staff ◽  
Multiple Reflections ◽  
Learning Space ◽  
Japanese University ◽  
Staff Members

This paper reports on a case study of learner-led study-abroad events in the language learning space at a Japanese University. We present multiple reflections on the events from different perspectives: the event organizer (student), an administrative staff member, and a learning advisor working at the center. We also introduce the support system that a group of administrative staff members and learning advisors are in charge of helping learners to hold their events. Moreover, throughout our reflections, several factors that made the learner-led study-abroad events sustainable and successful are demonstrated.

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