Velocity determination in layered systems with arbitrarily curved interfaces by means of wave field extrapolation of CMP data

Geophysics ◽  
1985 ◽  
Vol 50 (1) ◽  
pp. 63-76 ◽  
Author(s):  
C. P. A. Wapenaar ◽  
A. J. Berkhout
Keyword(s):  
Wave Field ◽  
Theoretical Approach ◽  
Synthetic Data ◽  
Layered Systems ◽  
The Subject

The paper starts with a brief review of conventional velocity determination procedures for plane‐layered systems. These methods assume hyperbolic moveout curves in common midpoint (CMP) data. It is shown that in layered systems with arbitrarily curved interfaces these methods fail since the moveout curves are nonhyperbolic. The subject of this paper is a wave‐theoretical approach to velocity determination. By means of wave field extrapolation of CMP data, nonhyperbolic moveout curves are transformed into hyperbolic ones. The proposed process is called velocity replacement (VR) since an inhomogeneous overburden is replaced by a homogeneous velocity medium. The effect of VR is illustrated on synthetic data. From the results it may be concluded that velocity determination after VR yields significantly more accurate results than velocity determination before VR. The technique of VR is also proposed as a preprocessing tool prior to stack in situations of nonhyperbolic moveout curves.

Harrison Decoded

2020 ◽  
Keyword(s):  
Theoretical Approach ◽  
Environmental Conditions ◽  
Collaborative Research ◽  
Electronic Equipment ◽  
The Public ◽  
Royal Observatory ◽  
The Subject ◽  
Written Descriptions ◽  
Pendulum Clock

This volume centres on a clock, known as Clock B, built in the mid-1970s that achieved considerable acclaim after an extraordinary performance in a 2015 peer-reviewed public trial at the Royal Observatory, Greenwich. The clock was built according to an understanding of John Harrison’s unique theoretical approach to making precision pendulum clocks, which defies the standard approaches to making accurate clocks. The clock represents the culmination of over forty years of collaborative research into Harrison’s writing on the subject, which is scattered across a number of manuscripts and a book, printed shortly before his death. Ostensibly, Harrison set out to describe how to make his precision pendulum clock, but it is a mixture of his peripheral interests. Horological information is almost completely lost among vitriolic sentiments relating to his experiences with the Board of Longitude. However, as one reviewer surmised: ‘we are sorry to say that the public will be disappointed’ and another concluded that ‘it can only be excused by superannuated dotage’. The chapters provides contextual history and documentation of the analysis and decoding of the cryptic written descriptions. It presents this in parallel to the modern horological story of making, finishing, and adjusting Clock B; the process of testing, using electronic equipment to monitor the its performance and reaction to changes in environmental conditions, and, indeed, the mechanics behind the various compensating features of the design.

Two Models of Public Opinion: Bacon's ‘New Logic’ and Diotima's ‘Tale of Love’ (The Prothero Lecture)

1974 ◽  
Vol 24 ◽  
pp. 79-96
Author(s):  
Samuel H. Beer
Keyword(s):  
United States ◽  
Public Policy ◽  
Eighteenth Century ◽  
Public Opinion ◽  
Theoretical Approach ◽  
Democratic Theory ◽  
The United States ◽  
Representative Government ◽  
The Subject ◽  
Work Done

It is appropriate that an American should address himself to the subject of public opinion. For, in terms of quantity, Americans have made the subject peculiarly their own. They have also invested it with characteristically American concerns. Most of the work done on the subject in the United States is oriented by a certain theoretical approach. This approach is democratic and rationalist. Both aspects create problems. In this paper I wish to play down the democratic problem, viz., how many of the voters are capable of thinking sensibly about public policy, and emphasize rather the difficulties that arise from modern rationalism. Here I take a different tack from most historians of the concept of public opinion, who, taking note of the origin of the term in the mid-eighteenth century, stress its connection with the rise of representative government and democratic theory.

scholarly journals Theoretical approach of teaching lithosphere in junior high school: A critical review of the content and objectives defined by the curriculum of the Ministry of Education

2017 ◽  
Vol 47 (2) ◽  
pp. 1024
Author(s):  
G. Leontakianakos ◽  
C. Vrachas ◽  
G. Baziotis ◽  
G. Soultati ◽  
G. Fermeli
Keyword(s):  
High School ◽  
Primary School ◽  
Junior High School ◽  
Theoretical Approach ◽  
Critical Review ◽  
Ministry Of Education ◽  
Curriculum Content ◽  
Main Research ◽  
Research Hypothesis ◽  
The Subject

The purpose of this study is an attempt to define the lithosphere concept, as described in the textbook “Geology-Geography” of the 1st Grade of junior highschool. Further we investigate whether the objectives of the corresponding chapter are being implemented according to the curriculum of the Ministry of Education. The main research hypothesis concentrates on the very limited cognitive background of the students regarding the lithosphere. It is based on the absence of a wellorganized framework of proportional and gradually increased and specialized flow of knowledge, as suggest the few generalised concepts on the subject of Geography taught on the 5th and 6th grade of the Primary School. According to the Curriculum of the “Geology–Geography” of the Ministry of Education, the lithosphere chapter requires fifteen didactic hours for a sum of nine complexes, mostly cognitive objectives. However, the textbook contains only five didactic hours, an indicator of an asymmetric state of the Curriculum. Our opinion about curriculum content itself, which describes the lithosphere, compared to the strictly scientific definition, is that it represents a simplistic approach and consequently the materialization of the cognitive goals is doubtful.

scholarly journals Variety of theoretical approaches to legal interpretation

2021 ◽  
pp. 109-114
Author(s):  
A. Yе. Shevchenko ◽  
S. V. Kudin
Keyword(s):  
Social Relations ◽  
Theoretical Approach ◽  
Special Kind ◽  
Integrative Approach ◽  
Legal Interpretation ◽  
True Nature ◽  
Theoretical Approaches ◽  
The Will ◽  
The Subject ◽  
The Law

The article explores the variety of theoretical approaches to legal interpretation. It has been determined that the variety of approaches to legal interpretation is due to the complexity of the nature of the origin of this phenomenon, the conditions for the development of post-non-classical science, and the recent influence of the paradigm of comparism, which assumes pluralism of opinions and ideas in legal research. It was found that in modern science there are four traditional theoretical approaches to the essence of legal interpretation. It has been determined that the content of the first approach is revealed within the framework of legal hermeneutics through a number of categories. The essence of the second approach (formal dogmatic or static) is expressed in the fact that the subject of interpretation must strictly and rigorously follow the letter of the law, establish only the meaning of the normative legal act, which the lawmaking body enshrined in it at the time of the publication of the act. That is why normative legal acts cannot, through interpretation, adapt to the changing economic, social, political, cultural internal and external conditions of public life. It is proved that the essence of the dynamic theoretical approach lies in the fact that the subject of legal interpretation adapts the normative legal act to the changes that occur in various social relations. It was found that there is a contradiction between the dynamic and static approaches in legal interpretation, which is reflected in the traditionally called objective and subjective theories of interpretation. According to the subjective theory, the purpose of legal interpretation is to establish the «will of the legislator», and according to the objective theory – to establish the «will of the law». It has been substantiated that the essence of the activity approach is that interpretation is considered as a special kind of legal activity aimed at understanding and clarifying the content of legal texts. The authors of this article point out that in order to establish the true nature of legal interpretation, the methodological foundations of the study should be presented much broader and more diverse, and not be limited only to traditional approaches. When studying it, a comprehensive, integrative approach is needed, which, based on the relevance of interdisciplinary relationships, would include logical, language (linguistic), philosophical, sociological, psychological, axiological (value), ethical, legal, historical, economic, political, mathematical and other substantiation of legal interpretation. Keywords: diversity, theoretical approach, legal interpretation, interpretive practice, integrative approach

Large‐scale three‐dimensional seismic models and their interpretive significance

Geophysics ◽  
1990 ◽  
Vol 55 (9) ◽  
pp. 1166-1182 ◽  
Author(s):  
Irshad R. Mufti
Keyword(s):  
Finite Difference ◽  
Wave Field ◽  
Large Scale ◽  
Three Dimensional ◽  
Synthetic Data ◽  
Real Data ◽  
The Real ◽  
Need To Evaluate ◽  
Zero Offset ◽  
Seismic Models

Finite‐difference seismic models are commonly set up in 2-D space. Such models must be excited by a line source which leads to different amplitudes than those in the real data commonly generated from a point source. Moreover, there is no provision for any out‐of‐plane events. These problems can be eliminated by using 3-D finite‐difference models. The fundamental strategy in designing efficient 3-D models is to minimize computational work without sacrificing accuracy. This was accomplished by using a (4,2) differencing operator which ensures the accuracy of much larger operators but requires many fewer numerical operations as well as significantly reduced manipulation of data in the computer memory. Such a choice also simplifies the problem of evaluating the wave field near the subsurface boundaries of the model where large operators cannot be used. We also exploited the fact that, unlike the real data, the synthetic data are free from ambient noise; consequently, one can retain sufficient resolution in the results by optimizing the frequency content of the source signal. Further computational efficiency was achieved by using the concept of the exploding reflector which yields zero‐offset seismic sections without the need to evaluate the wave field for individual shot locations. These considerations opened up the possibility of carrying out a complete synthetic 3-D survey on a supercomputer to investigate the seismic response of a large‐scale structure located in Oklahoma. The analysis of results done on a geophysical workstation provides new insight regarding the role of interference and diffraction in the interpretation of seismic data.

Modeling Driver Merging Behavior: A Repeated Game Theoretical Approach

2018 ◽  
Vol 2672 (20) ◽  
pp. 144-153 ◽  
Author(s):  
Kyungwon Kang ◽  
Hesham A. Rakha
Keyword(s):  
Decision Making ◽  
Theoretical Approach ◽  
Repeated Game ◽  
Simulation Software ◽  
Lane Changing ◽  
Microscopic Traffic Simulation ◽  
Game Theoretical Approach ◽  
The Subject ◽  
Merging Behavior ◽  
Decision Making Model

Various lane-changing models have been developed for use within microscopic traffic simulation software to replicate driver merging behavior. An understanding of human driving behavior, which can be gained through such modeling, will be critical in harmonizing emerging advanced vehicle technology, such as connected automated vehicles, with human drivers. Therefore, it is important to ensure that lane-changing models are clearly understood, appropriately designed, and carefully calibrated. An earlier study by Kang and Rakha proposed and developed a decision-making model for merging maneuvers using a game theoretical approach considering two drivers: the driver of the subject vehicle (DS) in an acceleration lane and the driver of the following lag vehicle (DL) in the target lane. The previous model assumed that the DS and DL decide on an action at the first point only, where the subject and lag vehicles are identified. The current study extends the Kang and Rakha model by introducing the concept of a repeated game, assuming that a lane change decision is made repeatedly to adjust to changes in surrounding conditions. For example, drivers often decide to change their initial decision as a result of conflicts with other drivers. A repeated game helps the proposed model produce more realistic decision-making in the lane-changing process. To evaluate the model, driver decisions at a certain stage, along with accumulated historical decision data, were extracted from Next Generation SIMulation (NGSIM) data. The validation results reveal that the proposed repeated game model produces considerable prediction accuracy (above 75%).

Redefining realness

2020 ◽  
Vol 9 (2) ◽  
pp. 101-126
Author(s):  
Stephen Turton
Keyword(s):  
Social Media ◽  
Discourse Analysis ◽  
Critical Discourse Analysis ◽  
Theoretical Approach ◽  
Critical Discourse ◽  
Neutral Term ◽  
The Subject ◽  
Public Scrutiny ◽  
Dictionary Definitions

Abstract This paper furthers the goal of “queering lexicography” (Nossem 2018) by proposing a theoretical approach to analysing dictionary definitions that replaces the traditional descriptive/prescriptive binary with a model of normativity influenced by performativity theory. This is demonstrated by a critical discourse analysis of how entries for lesbian, gay, and homosexual in four contemporary English dictionaries tacitly position homosexual as a neutral term against which lesbian and gay are sociolinguistically marked. The paper also stresses the need for researchers not only to analyse how normativity is embedded in dictionaries, but to recognize the extent to which lay dictionary-users are already aware of the normative potential of lexicography, whether they embrace it or condemn it. This is explored through an incident in which Merriam-Webster’s addition of the word genderqueer to its online dictionary in 2016 became the subject of public scrutiny and contestation on social media.

Vertical seismic profile migration using the Kirchhoff integral

Geophysics ◽  
1988 ◽  
Vol 53 (6) ◽  
pp. 786-799 ◽  
Author(s):  
P. B. Dillon
Keyword(s):  
Wave Equation ◽  
Wave Field ◽  
Near Field ◽  
Synthetic Data ◽  
Real Data ◽  
Seismic Profile ◽  
Processing Strategies ◽  
Receiver Array ◽  
Vsp Data ◽  
Kirchhoff Integral

Wave‐equation migration can form an accurate image of the subsurface from suitable VSP data. The image’s extent and resolution are determined by the receiver array dimensions and the source location(s). Experiments with synthetic and real data show that the region of reliable image extent is defined by the specular “zone of illumination.” Migration is achieved through wave‐field extrapolation, subject to an imaging procedure. Wave‐field extrapolation is based upon the scalar wave equation and, for VSP data, is conveniently handled by the Kirchhoff integral. The migration of VSP data calls for imaging very close to the borehole, as well as imaging in the far field. This dual requirement is met by retaining the near‐field term of the integral. The complete integral solution is readily controlled by various weighting devices and processing strategies, whose worth is demonstrated on real and synthetic data.

INVESTMENT ACTIVITY OF ENTERPRISES. PART I: THEORETICAL ASSUMPTIONS

2019 ◽  
Vol 20 (2) ◽  
pp. 135-144
Author(s):  
Olimpia Grabiec ◽  
Agnieszka Górka-Chowaniec
Keyword(s):  
Theoretical Approach ◽  
Necessary Condition ◽  
Investment Activity ◽  
Investment Projects ◽  
Theoretical Assumptions ◽  
The Subject

Due to the growing competitiveness, it is necessary to gain an advantage over competition, therefore, a necessary condition for obtaining it is continuous undertaking of various investment projects. The article discusses issues related to the investment activity of enterprises. In the publication, the author presented the theoretical approach to issues related to the investments of enterprises. The main purpose of this article is to analysis the investment activity of enterprises in terms of the subject literature.

Game Theoretical Approach to Model Decision Making for Merging Maneuvers at Freeway On-Ramps

2017 ◽  
Vol 2623 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Kyungwon Kang ◽  
Hesham A. Rakha
Keyword(s):  
Decision Making ◽  
Theoretical Approach ◽  
Model Parameters ◽  
Decision Making Process ◽  
Optimization Approach ◽  
Data Set ◽  
Deliberation Process ◽  
Proposed Model ◽  
Game Theoretical Approach ◽  
The Subject

Drivers of merging vehicles decide when to merge by considering surrounding vehicles in adjacent lanes in their deliberation process. Conflicts between drivers of the subject vehicles (i.e., merging vehicles) in an auxiliary lane and lag vehicles in the adjacent lane are typical near freeway on-ramps. This paper models a decision-making process for merging maneuvers that uses a game theoretical approach. The proposed model is based on the noncooperative decision making of two players, that is, drivers of the subject and lag vehicles, without consideration of advanced communication technologies. In the decision-making process, the drivers of the subject vehicles elect to accept gaps, and drivers of lag vehicles either yield or block the action of the subject vehicle. Corresponding payoff functions for two players were formulated to describe their respective maneuvers. To estimate model parameters, a bi-level optimization approach was used. The next generation simulation data set was used for model calibration and validation. The data set defined the moment the game started and was modeled as a continuous sequence of games until a decision is made. The defined merging decision-making model was then validated with an independent data set. The validation results reveal that the proposed model provides considerable prediction accuracy with correct predictions 84% of the time.

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