An analysis of 2D and 3D multiple attenuation for a canonical example

Geophysics ◽  
2005 ◽  
Vol 70 (6) ◽  
pp. A13-A28 ◽  
Author(s):  
Luc T. Ikelle
Keyword(s):  
Free Surface ◽  
Inverse Scattering ◽  
Three Dimensional ◽  
Homogeneous Medium ◽  
Vertical Plane ◽  
Multiple Attenuation ◽  
Out Of Plane ◽  
Seismic Acquisition ◽  
2D And 3D ◽  
The Relationship

Three-dimensional formulations of free-surface multiple attenuation for multioffset seismic data are well known. They are not yet used in practice because they require very dense source-receiver coverage, which is still out of reach with existing seismic-acquisition systems. The development of alternative solutions based on 2D algorithms depends on our understanding of the relationship between 2D and 3D free-surface multiple-attenuation methods. This paper attempts to enhance this understanding by establishing the relationship between 2D and 3D inverse scattering free-surface multiple attenuation. A 3D model consisting of three scattering points (one scattered point located in the vertical plane containing the shooting line and the other two points outside this plane) in a homogeneous medium (for which the exact pressure field is analytically known) is used to show that the 2D inverse scattering multiple-attenuation algorithm predicts all free-surface multiples as does its 3D counterpart but with some traveltime and amplitude errors. One implication of this result is that the current 2D inverse scattering multiple-attenuation algorithm, with an appropriate 2D-to-3D correction, can be used to predict the free-surface multiples for data containing out-of-plane scattering.

The Layer Project—Lost and Found in Digital Translation

Leonardo ◽  
2020 ◽  
Vol 53 (1) ◽  
pp. 86-87
Author(s):  
Julia Heurling
Keyword(s):  
Three Dimensional ◽  
Art Object ◽  
Lost And Found ◽  
2D And 3D ◽  
The Relationship

How can technology and digitalization be used to challenge and develop an analog idea? What happens in the translation from the analog to the digital? Can technology reveal previously hidden aspects of an art object? What happens to the relationship between art and viewer in the process of digitalization? The Layer Project, still in progress, originated in analog mode: cutting paper photographs into strips as layers. Digital filming became important for documenting the objects, as photographing them did not capture the changeability of their three-dimensional aspects. What happens at these borders of 2D and 3D, analog and digital? What defines them and what explains them? How can we compare them, relate them to each other? How are they different? Does media transform or simply transmit imagery? This statement also discusses how technology can be a tool for reflecting on an artwork—a tool to evaluate, develop and challenge an artistic concept.

An optimization of the inverse scattering multiple attenuation method for OBS and VC data

Geophysics ◽  
2002 ◽  
Vol 67 (4) ◽  
pp. 1293-1303 ◽  
Author(s):  
Luc T. Ikelle ◽  
Lasse Amundsen ◽  
Seung Yoo
Keyword(s):  
Free Surface ◽  
Data Storage ◽  
Inverse Scattering ◽  
Water Depth ◽  
Seismic Data ◽  
Computation Time ◽  
Ocean Bottom ◽  
Multiple Attenuation ◽  
Obs Data ◽  
Streamer Data

The inverse scattering multiple attenuation (ISMA) algorithm for ocean‐bottom seismic (OBS) data can be formulated in the form of a series expansion for each of the four components of OBS data. Besides the actual data, which constitute the first term of the series, each of the other terms is computed as a multidimensional convolution of OBS data with streamer data, and aims at removing one specific order of multiples. If the streamer data do not contain free‐surface multiples, we found that the computation of only the second term of the series is needed to predict and remove all orders of multiples, whatever the water depth. As the computation of the various terms of the series is the most expensive part of ISMA, this result can produce significant savings in computation time, even in data storage, as we no longer need to store the various terms of the series. For example, if the streamer data contained free‐surface multiples, OBS seismic data of 6‐s duration, corresponding to a geological model of the subsurface with 250‐m water depth, require the computation of five terms of the series for each of the four components of OBS data. With the new implementation, in which the streamer data do not contain free‐surface multiples, we need the computation of only one term of the series for each component of the OBS data. The saving in CPU time for this particular case is at least fourfold. The estimation of the inverse source signature, which is an essential part of ISMA, also benefits from the reduction of the number of terms needed for the demultiple to two because it becomes a linear inverse problem instead of a nonlinear one. Assuming that the removal of multiple events produces a significant reduction in the energy of the data, the optimization of this problem leads to a stable, noniterative analytic solution. We have also adapted these results to the implementation of ISMA for vertical‐cable (VC) data. This implementation is similar to that for OBS data. The key difference is that the basic model in VC imaging assumes that data consist of receiver ghosts of primaries instead of the primaries themselves. We have used the following property to achieve this goal. The combination of VC data with surface seismic data, which do not contain free‐surface multiples, allows us to predict free‐surface multiples and receiver ghosts as well as the receiver ghosts of primary reflections. However, if the direct wave arrivals are removed from the VC data, this combination will not predict the receiver ghosts of primary reflections. The difference between these two predictions produces data containing only receiver ghosts of primaries.

scholarly journals Wireless Sensor Network Target Localization Algorithm Based on Two- and Three-Dimensional Delaunay Partitions

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Chenguang Shao
Keyword(s):  
Three Dimensional ◽  
Target Localization ◽  
Wireless Sensor ◽  
Localization Algorithm ◽  
Target Node ◽  
Localization Accuracy ◽  
Localization Method ◽  
Anchor Nodes ◽  
2D And 3D ◽  
The Relationship

The target localization algorithm is critical in the field of wireless sensor networks (WSNs) and is widely used in many applications. In the conventional localization method, the location distribution of the anchor nodes is fixed and cannot be adjusted dynamically according to the deployment environment. The resulting localization accuracy is not high, and the localization algorithm is not applicable to three-dimensional (3D) conditions. Therefore, a Delaunay-triangulation-based WSN localization method, which can be adapted to two-dimensional (2D) and 3D conditions, was proposed. Based on the location of the target node, we searched for the triangle or tetrahedron surrounding the target node and designed the localization algorithm in stages to accurately calculate the coordinate value of the target. The relationship between the number of target nodes and the number of generated graphs was analysed through numerous experiments, and the proposed 2D localization algorithm was verified by extending it the 3D coordinate system. Experimental results revealed that the proposed algorithm can effectively improve the flexibility of the anchor node layout and target localization accuracy.

First motions from seismic sources in a semi-infinite homo-geneous medium overlain by an inhomogeneous layer

1975 ◽  
Vol 65 (5) ◽  
pp. 1435-1460
Author(s):  
R. S. Sidhu
Keyword(s):  
Free Surface ◽  
Horizontal Plane ◽  
Homogeneous Medium ◽  
Vertical Plane ◽  
Linear Increase ◽  
Strike Slip ◽  
Point Sources ◽  
Inhomogeneous Layer ◽  
Sh Waves ◽  
First Motion

Abstract The problem of seismic radiation from buried sources situated at a depth H below the free surface of an inhomogeneous layer of thickness h(< H) overlying a semi-infinite homogeneous medium is considered. First-motion solutions have been obtained at the free surface. Three point sources—slip on a horizontal plane, strike slip on a vertical plane and dip slip on a plane dipping at 45°—are considered in detail. Numerical results are computed for a linear increase of P and S velocities in the layer. Amplitude variations and first-motion signs of P, SV and SH waves are shown graphically for homogeneous and inhomogeneous media.

Collision course by transformation of coordinates and plane decomposition

Robotica ◽  
2009 ◽  
Vol 27 (4) ◽  
pp. 499-509 ◽  
Author(s):  
K. Bendjilali ◽  
F. Belkhouche
Keyword(s):  
Moving Objects ◽  
Mobile Robotics ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Dynamic Environment ◽  
Stationary Object ◽  
Detection Problem ◽  
Working Space ◽  
Direct Collision ◽  
2D And 3D

SUMMARYThis paper deals with the problem of collision course checking in a dynamic environment for mobile robotics applications. Our method is based on the relative kinematic equations between moving objects. These kinematic equations are written under polar form. A transformation of coordinates is derived. Under this transformation, collision between two moving objects is reduced to collision between a stationary object and a virtual moving object. In addition to the direct collision course, we define the indirect collision course, which is more critical and difficult to detect. Under this formulation, the collision course problem is simplified, and complex scenarios are reduced to simple scenarios. In three-dimensional (3D) settings, the working space is decomposed into two planes: the horizontal plane and the vertical plane. The collision course detection in 3D is studied in the vertical and horizontal planes using 2D techniques. This formulation brings important simplifications to the collision course detection problem even in the most critical and difficult scenarios. An extensive simulation is used to illustrate the method in 2D and 3D working spaces.

2D and 3D low frequency aerodynamics

2008 ◽  
Vol 112 (1136) ◽  
pp. 609-612
Author(s):  
L. H. van Zyl
Keyword(s):  
Three Dimensional ◽  
Low Frequency ◽  
Lattice Method ◽  
Panel Methods ◽  
Strip Theory ◽  
Doublet Lattice Method ◽  
2D And 3D ◽  
The Relationship ◽  
Aircraft Configurations ◽  
Theoretical Results

Abstract Unsteady aerodynamic loads on aircraft configurations are used for aeroelastic or flight dynamic analyses. The sources for deriving these loads include strip theory aerodynamics and three-dimensional panel methods. In some applications the behaviour of the unsteady air loads as the frequency approaches zero is important, and it is well known that the behaviour of strip theory aerodynamics employing the exact circulation function differs qualitatively from that of the three-dimensional panel methods such as the subsonic doublet lattice method (DLM). Theoretical results from an earlier study of the low frequency behaviour of the DLM are used here to show the relationship between the DLM and strip theory and the relationship is verified by a numerical example.

scholarly journals Remote nongenetic optical modulation of neuronal activity using fuzzy graphene

2020 ◽  
Vol 117 (24) ◽  
pp. 13339-13349 ◽  
Author(s):  
Sahil K. Rastogi ◽  
Raghav Garg ◽  
Matteo Giuseppe Scopelliti ◽  
Bernardo I. Pinto ◽  
Jane E. Hartung ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Cellular Systems ◽  
Therapeutic Interventions ◽  
One Dimensional ◽  
Hybrid Nanomaterial ◽  
Broadband Absorption ◽  
Cellular Electrophysiology ◽  
Graphene Flakes ◽  
Out Of Plane ◽  
2D And 3D

The ability to modulate cellular electrophysiology is fundamental to the investigation of development, function, and disease. Currently, there is a need for remote, nongenetic, light-induced control of cellular activity in two-dimensional (2D) and three-dimensional (3D) platforms. Here, we report a breakthrough hybrid nanomaterial for remote, nongenetic, photothermal stimulation of 2D and 3D neural cellular systems. We combine one-dimensional (1D) nanowires (NWs) and 2D graphene flakes grown out-of-plane for highly controlled photothermal stimulation at subcellular precision without the need for genetic modification, with laser energies lower than a hundred nanojoules, one to two orders of magnitude lower than Au-, C-, and Si-based nanomaterials. Photothermal stimulation using NW-templated 3D fuzzy graphene (NT-3DFG) is flexible due to its broadband absorption and does not generate cellular stress. Therefore, it serves as a powerful toolset for studies of cell signaling within and between tissues and can enable therapeutic interventions.

An inverse‐scattering series method for attenuating multiples in seismic reflection data

Geophysics ◽  
1997 ◽  
Vol 62 (6) ◽  
pp. 1975-1989 ◽  
Author(s):  
Arthur B. Weglein ◽  
Fernanda Araújo Gasparotto ◽  
Paulo M. Carvalho ◽  
Robert H. Stolt
Keyword(s):  
Free Surface ◽  
Inverse Scattering ◽  
Structural Information ◽  
Added Value ◽  
Ocean Bottom ◽  
Inversion Process ◽  
Seismic Reflection Data ◽  
Multiple Attenuation ◽  
Inverse Scattering Series ◽  
Internal Multiples

We present a multidimensional multiple‐attenuation method that does not require any subsurface information for either surface or internal multiples. To derive these algorithms, we start with a scattering theory description of seismic data. We then introduce and develop several new theoretical concepts concerning the fundamental nature of and the relationship between forward and inverse scattering. These include (1) the idea that the inversion process can be viewed as a series of steps, each with a specific task; (2) the realization that the inverse‐scattering series provides an opportunity for separating out subseries with specific and useful tasks; (3) the recognition that these task‐specific subseries can have different (and more favorable) data requirements, convergence, and stability conditions than does the original complete inverse series; and, most importantly, (4) the development of the first method for physically interpreting the contribution that individual terms (and pieces of terms) in the inverse series make toward these tasks in the inversion process, which realizes the selection of task‐specific subseries. To date, two task‐specific subseries have been identified: a series for eliminating free‐surface multiples and a series for attenuating internal multiples. These series result in distinct algorithms for free‐surface and internal multiples, and neither requires a model of the subsurface reflectors that generate the multiples. The method attenuates multiples while preserving primaries at all offsets; hence, these methods are equally well suited for subsequent poststack structural mapping or prestack amplitude analysis. The method has demonstrated its usefulness and added value for free‐surface multiples when (1) the overburden has significant lateral variation, (2) reflectors are curved or dipping, (3) events are interfering, (4) multiples are difficult to identify, and (5) the geology is complex. The internal‐multiple algorithm has been tested with good results on band‐limited synthetic data; field data tests are planned. This procedure provides an approach for attenuating a significant class of heretofore inaccessible and troublesome multiples. There has been a recent rejuvenation of interest in multiple attenuation technology resulting from current exploration challenges, e.g., in deep water with a variable water bottom or in subsalt plays. These cases are representative of circumstances where 1-D assumptions are often violated and reliable detailed subsurface information is not available typically. The inverse scattering multiple attenuation methods are specifically designed to address these challenging problems. To date it is the only multidimensional multiple attenuation method that does not require 1-D assumptions, moveout differences, or ocean‐bottom or other subsurface velocity or structural information for either free‐surface or internal multiples. These algorithms require knowledge of the source signature and near‐source traces. We describe several current approaches, e.g., energy minimization and trace extrapolation, for satisfying these prerequisites in a stable and reliable manner.

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