Random rays and seismic amplitude anomalies

Geophysics ◽  
1988 ◽  
Vol 53 (7) ◽  
pp. 903-907 ◽  
Author(s):  
Benjamin White ◽  
Balan Nair ◽  
Alvin Bayliss
Keyword(s):  
Plane Waves ◽  
Propagation Distance ◽  
Three Dimensions ◽  
Single Plane ◽  
Seismic Amplitude ◽  
Random Occurrence ◽  
Amplitude Anomaly ◽  
First Occurrence ◽  
Finite Distance ◽  
Homogeneous Media

We give an explanation of the phenomenon, sometimes observed in exploration seismology, of anomalously large amplitudes which seem inconsistent with the traveltime curves when the data are interpreted as resulting from reflections from smooth interfaces of piece‐wise homogeneous media. Monte Carlo simulations illustrate how this phenomenon can occur when the homogeneous media have small, smooth, random velocity fluctuations which vary on a length scale which is large compared with a wavelength but small compared with the propagation distance. Synthetic gathers of reflections from a single plane‐stratified layer with and without the random lateral inhomogeneities produce an amplitude anomaly which is related to the random occurrence of a caustic; limit theorems for stochastic differential equations provide a theory. Theoretical curves, giving the probability of first occurrence of this phenomenon along a ray as a function of propagation distance (for plane waves and for point and line sources in two and three dimensions) are qualitatively similar: they have an initial flat portion where amplitude anomalies are very unlikely, rise to a peak at the distance most likely for first occurrence, and decay exponentially to zero, thus predicting that the phenomenon will occur at some finite distance with probability one.

Study of wave attenuation in concrete

1993 ◽  
Vol 8 (9) ◽  
pp. 2344-2353 ◽  
Author(s):  
J-M. Berthelot ◽  
Souda M. Ben ◽  
J.L. Robert
Keyword(s):  
Experimental Study ◽  
Plane Wave ◽  
Wave Attenuation ◽  
Plane Waves ◽  
Propagation Distance ◽  
Experimental Results ◽  
The Other ◽  
Wave Frequency ◽  
Concrete Composition ◽  
Analytical Expression

The experimental study of wave attenuation in concrete has been achieved in the case of the propagation of plane waves in concrete rods. Different mortars and concretes have been investigated. A transmitter transducer coupled to one of the ends of the concrete rod generates the propagation of a plane wave in the rod. The receiver transducer, similar to the previous one, is coupled to the other end of the rod. The experimental results lead to an analytical expression for wave attenuation as function of the concrete composition, the propagation distance, and the wave frequency.

scholarly journals Analisis Simulasi Kinematik Mesin Gergaji Dengan Metode Bilangan Kompleks

2020 ◽  
Vol 5 (2) ◽  
pp. 134-139
Author(s):  
Rizky Arman ◽  
Yovial Mahyoedin ◽  
Yovial Mahyoedin
Keyword(s):  
Mathematical Method ◽  
Computer Technology ◽  
Three Dimensions ◽  
Planar Motion ◽  
Spatial Motion ◽  
Kinematics Analysis ◽  
Single Plane ◽  
Power Train ◽  
Gear Trains ◽  
Polygon Method

AbstrakAKinematika dan dinamika mesin melibatkan desain mesin atas dasar kebutuhan gerak mereka. Kombinasi bagian yang saling berhubungan memiliki gerakan yang pasti dan mampu melakukan pekerjaan yang berguna dapat disebut mesin. Mekanisme adalah komponen dari mesin yang terdiri dari dua atau lebih badan diatur sedemikian rupa sehingga gerakan satu memaksa gerakan yang lain. Desain kereta listrik otomotif (sejenis mesin) sangat  ditentukan oleh beberapa mekanisme, termasuk hubungan slider-engkol, cam dan follower hubungan, dan kereta gigi. Banyak mekanisme yang melibatkan gerak planar, gerak dalam satu pesawat atau di aset bidang sejajar. Kasus yang lebih umum, gerak spasial, berlaku untuk mekanisme di mana gerakan harus dijelaskan dalam tiga dimensi. Analisis kinematika dilakukan di bawah grafis pada umumnya, seperti metode poligon yang menangkap mekanisme dalam satu saat. Cara alternatif lain untuk masalah ini adalah melibatkan metode matematika. Solusi ini memberikan cara yang akurat dan tercepat karena didukung oleh teknologi komputer. Tujuan dari proyek ini adalah untuk menentukan rumus untuk posisi, kecepatan, dan pernyataan percepatan mesin gergaji dengan menggunakan Mathlab. Kata kunci: mekanisme, gerak (posisi, kecepatan dan percepatan), metode poligon AbstractKinematics and dynamics of machinery involve the design of machines on the basis of their motion requirements. A combination of interrelated parts having definite motions and capable of performing useful work may be called a machine. A mechanism is a component of a machine consisting of two or more bodies arranged so that the motion of one compels the motion of the others. The design of an automotive power train (a type of machine) is concerned with several mechanism, including slider-crank linkages, cam and follower linkages, and gear trains. Many mechanisms undergo planar motion, motion in a single plane or in asset of parallel planes. The more general case, spatial motion, applies to mechanism in which the motion must be described in three dimensions. Kinematics analysis is done under graphically in general, such as polygon method which capture the mechanism in one moment. Another way to alternate this problem is involve any mathematical method. This solution gave the accurate and fastest way because supported by computer technology. The aim of this project is to determine the formula for position, velocity, and acceleration statement of the sawing machine by using Mathlab.Keywords: mechanism, motion (position, velocity and acceleration), polygon method

On the impact of alternative seismic time imaging methods on subsurface fault mapping in the northernmost Molasse Basin, Switzerland

2020 ◽  
Vol 8 (4) ◽  
pp. SQ1-SQ13
Author(s):  
Christoph G. Eichkitz ◽  
Sarah Schneider ◽  
Andreas B. Hölker ◽  
Philip Birkhäuser ◽  
Herfried Madritsch
Keyword(s):  
Fault Zone ◽  
Three Dimensions ◽  
Small Scale ◽  
Zone Model ◽  
Molasse Basin ◽  
Data Set ◽  
Volume Comparison ◽  
Imaging Methods ◽  
Seismic Amplitude ◽  
The Impact

The identification and characterization of tectonic faults in the subsurface represent key aspects of geologic exploration activities across the world. We have evaluated the impact of alternative seismic time imaging methods on initial subsurface fault mapping in three dimensions in the form of a case study situated in the most external foreland of the European Central Alps (the northernmost Molasse Basin). Four different seismic amplitude volumes of one and the same 3D seismic data set, differing in imaging technologies and parameterizations applied, were considered for the interpretation of a fault zone dissecting a Mesozoic sedimentary sequence that is characterized by a pronounced mechanical stratigraphy and has witnessed a multiphase tectonic evolution. For this purpose, we interpreted each seismic amplitude volume separately. In addition, we computed a series of seismic attributes individually for each volume. Comparison of the different data interpretations revealed consistent results concerning the mapping of the seismic marker horizons and main fault segments. Deviations concern the apparent degree of vertical and lateral fault zone segmentation and the occurrence of small-scale fault strands that may be regarded as important fault kinematic indicators. The compilation of all fault interpretations in map form allows the critical assessment of the robustness of the initial seismic fault mapping, highlighting well-constrained from poorly defined fault zone elements. We conclude that the consideration of multiple seismic processing products for subsurface fault mapping is advisable to evaluate general imaging uncertainties and potentially guide the development of fault zone model variants to tackle previously discussed aspects of conceptual interpretation uncertainties.

A new exploration tool for subtle stratigraphic traps in the offshore Nile Delta, Egypt

2019 ◽  
Vol 26 (3) ◽  
pp. 434-447
Author(s):  
Amir M. S. Lala ◽  
Amr Talaat
Keyword(s):  
Seismic Data ◽  
Nile Delta ◽  
The Other ◽  
Class I ◽  
Class Iii ◽  
Gas Reservoir ◽  
Seismic Amplitude ◽  
Amplitude Anomaly ◽  
Exploration Tool ◽  
Gas Bearing

The offshore Nile Delta Basin is considered as one of the most promising hydrocarbon provinces in Egypt, with an excellent potential for gas and condensate reserves following future exploration. Most of the discoveries in this basin, such as the reservoirs of the Upper Miocene and the Middle–Upper Pliocene, have been enabled by the use of a direct hydrocarbon indicator (DHI), based on a class III seismic amplitude v. offset (AVO) anomaly. However, there are gas-bearing formations in the Lower Pliocene that have been successfully tested where the sand did not show any seismic amplitude anomaly in full stacks or in near- and far-offset sub-stacks. The AVO analysis of this sand reservoir is referred to as AVO class II-P. Another case of a subtle AVO class I anomaly in a Lower Pliocene gas reservoir has also been tested by three wells.These variations in AVO types push us to find a new methodology to reduce the risk of unsuccessful exploration wells, mainly using seismic data. The enhanced AVO pseudo-gradient attribute (EAP) has previously been used in other studies, mainly to highlight AVO class III anomalies. However, in the present paper, we demonstrate a workflow to identify all the principal AVO classes observed in this province. Computing the EAP attribute from our data, we find that AVO class I has negative EAP values, while the other classes have positive values. Class III and classes II and II-P may be distinguished from each other as the former yields a strong positive EAP value, whereas the latter two classes yield weak EAP responses.After determining the AVO class, we define and use a new model attribute, herein termed NM, to differentiate between gas- and water-bearing formations for each class of AVO anomaly found in this province. This new method was successfully tested in many areas in the Nile Delta Basin, where it has helped to identify subtle anomalies and thereby open the gate for further exploration activities in the area.

scholarly journals A framework for quantifying properties of 3-dimensional movement-based signals

2010 ◽  
Vol 56 (3) ◽  
pp. 327-336 ◽  
Author(s):  
Shaun Td New ◽  
Richard A Peters
Keyword(s):  
Three Dimensions ◽  
Tail Flick ◽  
Signal Design ◽  
3D Animation ◽  
3D Display ◽  
Single Plane ◽  
3 Dimensional ◽  
Tail Tip ◽  
Detector Model ◽  
New Framework

Abstract Understanding how signal properties are optimized for the reliable transmission of information requires accurate description of the signal in time and space. For movement-based signals where movement is restricted to a single plane, measurements from a single viewpoint can be used to consider a range of viewing positions based on simple geometric calculations. However, considerations of signal properties from a range of viewing positions for movements extending into three-dimensions (3D) are more problematic. We present here a new framework that overcomes this limitation, and enables us to quantify the extent to which movement-based signals are view-specific. To illustrate its application, a Jacky lizard tail flick signal was filmed with synchronized cameras and the position of the tail tip digitized for both recordings. Camera alignment enabled the construction of a 3D display action pattern profile. We analyzed the profile directly and used it to create a detailed 3D animation. In the virtual environment, we were able to film the same signal from multiple viewing positions and using a computational motion analysis algorithm (gradient detector model) to measure local image velocity in order to predict view dependent differences in signal properties. This approach will enable consideration of a range of questions concerning movement-based signal design and evolution that were previously out of reach.

scholarly journals TIMELIKE GEODESIC MOTION IN HORAVA–LIFSHITZ SPACE–TIME

2010 ◽  
Vol 25 (07) ◽  
pp. 1439-1448 ◽  
Author(s):  
JUHUA CHEN ◽  
YONGJIU WANG
Keyword(s):  
Initial Conditions ◽  
Detailed Balance ◽  
Critical Value ◽  
Space Time ◽  
Three Dimensions ◽  
Geodesic Motion ◽  
Timelike Geodesic ◽  
Particle Orbit ◽  
Renormalizable Theory ◽  
Finite Distance

Recently a nonrelativistic renormalizable theory of gravitation has been proposed by P. Horava. When restricted to satisfy the condition of detailed balance, this theory is intimately related to topologically massive gravity in three dimensions, and the geometry of the Cotton tensor. At long distances, this theory is expected to flow to the relativistic value λ = 1, and could therefore serve as a possible candidate for a UV completion of Einstein's general relativity or an infrared modification thereof. In this paper under allowing the lapse function to depend on the spatial coordinates xi as well as t, we obtain the spherically symmetric solutions. And then by analyzing the behavior of the effective potential for the particle, we investigate the timelike geodesic motion of particle in the Horava–Lifshitz space–time. We find that the nonradial particle falls from a finite distance to the center along the timelike geodesics when its energy is in an appropriate range. However, we find that it is complexity for radial particle along the timelike geodesics. There are three different cases due to the energy of radial particle: (i) when the energy of radial particle is higher than a critical value EC, the particle will fall directly from infinity to the singularity; (ii) when the energy of radial particle equals to the critical value EC, the particle orbit at r = rC is unstable, i.e. the particle will escape from r = rC to the infinity or to the singularity, depending on the initial conditions of the particle; (iii) when the energy of radial particle is in a proper range, the particle will rebound to the infinity or plunge to the singularity from a infinite distance, depending on the initial conditions of the particle.

Bright spots, milligals, and gammas

Geophysics ◽  
1982 ◽  
Vol 47 (12) ◽  
pp. 1693-1705
Author(s):  
Alan O. Ramo ◽  
James W. Bradley
Keyword(s):  
Seismic Data ◽  
Magnetic Data ◽  
Amplitude Analysis ◽  
Seismic Amplitude ◽  
The North ◽  
Gravity And Magnetic ◽  
Amplitude Anomaly ◽  
North Edge ◽  
Gravity And Magnetic Data ◽  
Seismic Anomaly

Spatially discontinuous high‐amplitude seismic reflections were encountered in seismic data acquired in the early 1970s in northeast Louisiana and southwest Arkansas. Large acoustic impedance contrasts are known to result from gaseous hydrocarbon accumulations. However, amplitude anomalies may also result from large density and velocity contrasts which are geologically unrelated to hydrocarbon entrapment. A well drilled on the northeast Louisiana amplitude anomaly encountered 300 ft of rhyolite at a depth of 6170 ft. Subsequent gravity and total field magnetic profiles across the feature revealed the presence of 0.2 mgal and 17 gamma anomalies, respectively. The measured magnetic susceptibility of the rhyolite was 0.0035 emu and the measured density contrast was [Formula: see text]. Model studies based on the seismically determined areal extent of the anomaly and the measured thickness of rhyolite accounted for the observed gravity and magnetic anomalies. The southwest Arkansas amplitude anomaly was a sheet‐like reflection which terminated to the north and west within the survey area. Two north‐south gravity profiles exhibited a negative character over the sheet‐like reflector but did not exhibit a clear spatial correlation with the north limit of the seismic anomaly. Two north‐south magnetic profiles exhibited tenuous 4 gamma anomalies which appeared to be spatially correlated with the interpreted north edge of the seismic anomaly. A subsequent wildcat well encountered no igneous material but did penetrate 200 ft of salt at about 7500 ft. Reassessment of the gravity and magnetic data indicated that this seismic amplitude anomaly is not attributable to an intrasedimentary igneous source; it suggested a salt‐related 0.2 to 0.3 mgal minimum coextensive with the observed seismic amplitude anomaly. Present amplitude analysis technology would treat these seismic data with suspicion. However, gravity and magnetic data acquisition can provide a relatively inexpensive means for evaluation and verification of amplitude anomalies and thus should be an adjunct for land seismic exploration utilizing amplitude analysis.

A pteranodontid pterosaur from the Early Cretaceous of Peru, with comments on the relationships of Cretaceous pterosaurs

1989 ◽  
Vol 63 (5) ◽  
pp. 669-677 ◽  
Author(s):  
S. Christopher Bennett
Keyword(s):  
Early Cretaceous ◽  
Three Dimensions ◽  
First Occurrence

The first occurrence of a pterosaur fossil from the Early Cretaceous of Peru is reported. The specimen consists of a nearly complete right humerus of a pteranodontid pterosaur preserved in three dimensions, presumably in a concretion. The Pteranodontidae is rediagnosed, and included genera and materials are listed. The Nyctosauridae and Dsungaripteridae are also diagnosed on the basis of postcranial characters, and the relationships of those three taxa plus the Azhdarchidae are discussed. The species Santanadactylus spixi Wellnhofer (1985) is reassigned to the Dsungaripteridae.

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