3D symmetric sampling of sparse acquisition geometries

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. WB3-WB14 ◽  
Author(s):  
Gijs J. Vermeer
Keyword(s):  
Single Point ◽  
Azimuthal Anisotropy ◽  
Seismic Surveys ◽  
Coil Geometry ◽  
Migration Velocity Analysis ◽  
Technological Developments ◽  
Spatial Coordinates ◽  
Symmetric Sampling ◽  
The Given ◽  
Dense Sampling

3D symmetric sampling introduced in the 1990s is characterized by dense sampling of two of the four spatial coordinates. The two sparsely sampled coordinates determine the periodicity of the geometry and the dimension of the offset-vector tiles that can be used to generate pseudocommon-offset-vector gathers. These gathers turn out to be useful for prestack processing applications, such as regularization, migration velocity analysis, and azimuthal anisotropy analysis. Although single-point acquisition is the ideal acquisition method, it is not necessarily better than array-based acquisition. Field arrays are still useful in suppressing noise and need not harm signal in most practical cases. In hybrid geometries three spatial coordinates are sampled densely. In all published cases at least two of the three are sampled quite coarsely and may not provide the best quality for the given trace density. Coil geometry (sailing in circles) is a special case of wide-azimuth towed streamer acquisition. It is essentially a random geometry that should be modifiable into a geometry with regularly sampled midpoints, absolute offsets and azimuths. Despite recent technological developments, the basic idea of 3D symmetric sampling still is a highly useful principle for the design of land and marine 3D seismic surveys.

scholarly journals Partitioning the colonization and extinction components of beta diversity: Spatiotemporal species turnover across disturbance gradients

2020 ◽  
Author(s):  
Shinichi Tatsumi ◽  
Joachim Strengbom ◽  
Mihails Čugunovs ◽  
Jari Kouki
Keyword(s):  
Plant Communities ◽  
Beta Diversity ◽  
Species Turnover ◽  
Single Point ◽  
Relative Importance ◽  
Dynamic Nature ◽  
Colonization Dynamics ◽  
Per Se ◽  
The Given ◽  
Temporal Species Turnover

ABSTRACTChanges in species diversity often result from species losses and gains. The dynamic nature of beta diversity (i.e., spatial variation in species composition) that derives from such temporal species turnover, however, has been largely overlooked. Here, we disentangled extinction and colonization components of beta diversity by using the sets of species that went locally extinct and that newly colonized the given sites. We applied this concept of extinction and colonization beta diversity to plant communities that have been repeatedly measured in experimentally disturbed forests. We first found no difference in beta diversity across disturbance gradients when it was analyzed for communities at a single point in time. From this result, we might conclude that disturbance caused no impact on how species assemble across space. However, when we analyzed the extinction and colonization beta diversity, both measures were found to be significantly lower in disturbed sites compared to undisturbed sites. These results indicate that disturbance removed similar subsets of species across space, making communities differentiate, but at the same time induced spatially uniform colonization of new species, causing communities to homogenize. Consequently, the effects of these two processes canceled each other out. The relative importance of extinction and colonization components per se also changed temporally after disturbance. Analyses using extinction and colonization beta diversity allowed us to detect nonrandom dis- and re-assembly dynamics in plant communities. Our results suggest that common practices of analyzing beta diversity at one point in time can mask significant variation driven by disturbance. Acknowledging the extinction–colonization dynamics behind beta diversity is essential for understanding the spatiotemporal organization of biodiversity.

NORTH WEST SHELF 3-D SEISMIC—A DECADE OF DEVELOPMENTS

1993 ◽  
Vol 33 (1) ◽  
pp. 315
Author(s):  
P.S. Vaughan
Keyword(s):  
Joint Venture ◽  
Spatial Sampling ◽  
Seismic Surveys ◽  
North West ◽  
The North ◽  
Technological Developments

Woodside as Operator, on behalf of three Joint Venture groups, over the last decade has acquired eight 3-D seismic surveys covering some 4 600 km2 over the Rankin Trend and Dampier Sub-Basin Production Licences and Exploration Permits on the North West Shelf of Australia. This area represents approximately 45 per cent coverage of the present Woodside operated acreage in the area. The acquisition, processing and interpretation technology and also the benefits derived from the 3-D technique have changed remarkably since the first North West Shelf 3-D survey in 1981. This paper focusses on the main technological developments in 3-D seismic, particularly involving multi-source and streamer technology, increased spatial sampling and interpretation techniques which have changed the role of 3-D seismic in Exploration strategies through the 1980s and into the 1990s.

scholarly journals Riemannian Means as Solutions of Variational Problems

2006 ◽  
Vol 9 ◽  
pp. 86-103 ◽  
Author(s):  
Luís Machado ◽  
F. Silva Leite ◽  
Knut Hüper
Keyword(s):  
Riemannian Manifold ◽  
Variational Problem ◽  
Lie Groups ◽  
Riemannian Manifolds ◽  
Single Point ◽  
Variational Problems ◽  
Compact Lie Groups ◽  
Data Set ◽  
The Given ◽  
Best Fit

We formulate a variational problem on a Riemannian manifoldMwhose solutions are piecewise smooth geodesies that best fit a given data set of time labelled points inM. By a limiting process, these solutions converge to a single point inM. which we prove to be the Riemannian mean of the given points for some particular Riemannian manifolds such as Euclidean spaces, connected and compact Lie groups, and spheres.

scholarly journals The arduino SCADA training at the Mambaul Ulum Vocational High School, Gresik

2021 ◽  
Vol 6 (9) ◽  
pp. 1728-1733
Author(s):  
Rini Puji Astutik ◽  
Hendra Ari Winarno ◽  
Eliyani Eliyani ◽  
Denny Irawan ◽  
Raafi' Yanuar Purnama Arifian ◽  
...  
Keyword(s):  
High School ◽  
Data Acquisition ◽  
Supervisory Control ◽  
Technical Skills ◽  
Vocational Schools ◽  
Vocational High School ◽  
Left Behind ◽  
Technological Developments ◽  
The Given

Students will be left behind in technological developments unless teachers in vocational schools constantly update their technical skills. One of such developments that is widely applied in the industry is the Supervisory Control and Data Acquisition (SCADA) application. This service aimed to share knowledge about SCADA technology with students of the Mambaul Ulum Vocational High School, Gresik in preparation for their entry into the industrial world. The results of the activity showed an increase in students' knowledge and mastery of Arduino which functions as a SCADA. This is further proven by the participants’ ability to solve the given case study.

scholarly journals ALGORITHMS FOR CALCULATING GEODETIC HEIGHTS AND LATITUDES BY RECTANGULAR COORDINATES IN THE MERIDIAN ELLIPSE PLANE

2021 ◽  
Vol 26 (5) ◽  
pp. 5-16
Author(s):  
Alexander V. Elagin ◽  
◽  
Natalia N. Kobeleva ◽  
Keyword(s):  
Reference Values ◽  
Intersection Point ◽  
The Other ◽  
Geodetic Coordinates ◽  
The Earth ◽  
Straight Line ◽  
Rectangular Coordinates ◽  
Spatial Coordinates ◽  
Point Of Intersection ◽  
The Given

Owing to the widespread use of GNSS technologies in geodetic practice, the problem arises of transition from rectangular spatial coordinates of points to spatial geodetic coordinates, which are necessary for the transition to flat rectangular coordinates in the Gauss-Kruger projection. The authors proposed five algorithms for converting rectangular coordinates of points in the plane of the meridian ellipse into geodetic heights and latitudes. The first two algorithms are geometrically related to the intersection point of the ellipse with the normal passing through the point at which the rectangular spatial coordinates were obtained. The formulas of the other three algorithms are based on the geometric relationships of the point of intersection of the meridian ellipse with the straight line connecting the point with the center of curvature of the meridian. As a result of the experiments, deviations of the calculated latitudes and heights from the reference values of the given grid of geodetic coordinates were obtained. The formulas were tested not only for points under and on the earth's surface, but also outside the earth at different heights up to an altitude of 20,000 km.

Revisiting the Concept of Virtualized Residential Gateways

2021 ◽  
pp. 272-304
Author(s):  
Jorge Proença ◽  
Tiago Cruz ◽  
Paulo Simões ◽  
Edmundo Monteiro
Keyword(s):  
Local Area Network ◽  
Single Point ◽  
Access Network ◽  
Local Area ◽  
Area Network ◽  
Network Service Provider ◽  
Competitive Edge ◽  
Technological Developments ◽  
Technical Advances ◽  
To Come

A diversity of technical advances in the field of network and systems virtualization have made it possible to consolidate and manage resources in an unprecedented scale. These advances have started to come out of the data centers, spreading towards the network service provider (NSP) and telecommunications operator infrastructure foundations, from the core to the edge networks, the access network, and the customer premises LAN (local area network). In this context, the residential gateway (RGW) constitutes an ideal candidate for virtualization, as it stands between the home LAN and the access network, imposing a considerable cost for the NSP while constituting a single point of failure for all the services offered to residential customers. This chapter presents the rationale for the virtual RGW (vRGW) concept, providing an overview of past and current implementation proposals and discussing how recent technological developments in key areas such as networking and virtualization have given a competitive edge to a RGW virtualization scenario, when compared with traditional deployments.

The Use of Rodrigues-Frank Space for Representing Discrete Misorientation Distributions

2005 ◽  
Vol 495-497 ◽  
pp. 157-166 ◽  
Author(s):  
Leo Kestens ◽  
Kim Verbeken ◽  
R. Decocker ◽  
Roumen H. Petrov ◽  
Patricia Gobernado ◽  
...  
Keyword(s):  
Single Point ◽  
Carbon Steels ◽  
Recrystallization Process ◽  
Large Set ◽  
Low Carbon ◽  
Triple Junctions ◽  
Misorientation Distribution ◽  
Orientation Relations ◽  
Before And After ◽  
The Given

It is often assumed that the texture formation during solid state transformations in low carbon steels critically depends on the local crystallographic misorientation at the interface between transformed and not yet transformed material volume. In some cases, a theoretical crystallographic orientation relation can be presumed as a necessary prerequisite for the transformation to occur. Classical examples of such misorientation conditions in steel metallurgy are the orientation relations between parent and product grains of the allotropic phase transformation from austenite to ferrite (or martensite) or the hypothetical <110>26.5º misorientation between growing nuclei and disappearing grains in a recrystallization process. One way to verify the validity of such misorientation conditions is to carry out an experiment in which the transformation is partially completed and then observe locally, at the transformation interface, whether or not the presumed crystallographic condition is complied with. Such an experiment will produce a large set of misorientation data. As each observed misorientation Dg is represented by a single point in the Rodrigues-Frank (RF) space, a distribution of discrete misorientation points is obtained. This distribution is compared with the reference misorientation Dgr, corresponding to a specific physical condition, by determining the number fraction dn of misorientations that are confined within a narrow misorientation volume element dw around the given reference misorientation Dgr. In order to evaluate whether or not the proposed misorientation condition is obeyed, the number fraction dn of the experimentally measured distribution must be compared with the number fractions dr obtained for a random misorientation distribution. The ratio dn/dr can be interpreted as the number intensity fi of the given reference misorientation Dgr. This method was applied on the observed local misorientations between the recrystallizing grains growing into the single crystal matrix of a Fe-2.8%Si alloy. It was found that the number intensity of the <110>26.5º misorientation increased with a factor 10 when the misorientation distribution was evaluated before and after the growth stage. In another example the method was applied to the misorientations measured at the local interface between parent austenite and product martensite grains of a partially transformed Fe-28%Ni alloy. It could be established that the Nishiyama- Wasserman relations ({111}g//{110}a <112>g//<110>a) prevail over the Kurdjumov-Sachs relations ({111}g//{110}a and <110>g//<111>a) although a considerable scatter was observed around either of the theoretical correspondences. A full parametric misorientation description was also applied to evaluate the relative grain boundary energies associated with a set of crystallographic misorientations observed near triple junctions in Fe-2%Si. In this instance it was found that the boundaries carrying a misorientation of the type <110>w carry a lower interfacial energy than the <100> or <111> type boundaries.

3-D symmetric sampling

Geophysics ◽  
1998 ◽  
Vol 63 (5) ◽  
pp. 1629-1647 ◽  
Author(s):  
Gijs J. O. Vermeer
Keyword(s):  
Seismic Data ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Essential Elements ◽  
Spatial Behavior ◽  
Spatial Continuity ◽  
Geometry Design ◽  
Orthogonal Geometry ◽  
Spatial Coordinates ◽  
Symmetric Sampling

Three‐dimensional seismic surveys have become accepted in the industry as a means of acquiring detailed information on the subsurface. Yet, the cost of 3-D seismic data acquisition is and will always be considerable, making it highly important to select the right 3-D acquisition geometry. Up till now, no really comprehensive theory existed to tell what constitutes a good 3-D geometry and how such a geometry can be designed. The theory of 3-D symmetric sampling proposed in this paper is intended to fill this gap and may serve as a sound basis for 3-D geometry design and analysis. Methods and theories for the design of 2-D surveys were developed in the 1980s. Anstey proposed the stack‐array approach, Ongkiehong and Askin the hands‐off acquisition technique, and Vermeer introduced symmetric sampling theory. In this paper, the theory of symmetric sampling for 2-D geometries is expanded to the most important 3-D geometries currently in use. Essential elements in 3-D symmetric sampling are the spatial properties of a geometry. Spatial aspects are important because most seismic processing programs operate in some spatial domain by combining neighboring traces into new output traces, and because it is the spatial behavior of the 3-D seismic volume that the interpreter has to translate into maps. Over time, various survey geometries have bee devised for the acquisition of 3-D seismic data. All geometries constitute some compromise with respect to full sampling of the 5-D prestack wavefield (four spatial coordinates describing shot and receiver position, and traveltime as fifth coordinate). It turns out that most geometries can be considered as a collection of 3-D subsets of the 5-D wavefield, each subset having only two varying spatial coordinates. The spatial attributes of the traces in each subset vary slowly and regularly, and this property provides spatial continuity to the 3-D survey. The spatial continuity can be exploited optimally if the subsets are properly sampled and if their extent is maximized. The 2-D symmetric sampling criteria—equal shot and receiver intervals, and equal shot and receiver patterns—apply also to 3-D symmetric sampling but have to be supplemented with additional criteria that are different for different geometries. The additional criterion for orthogonal geometry (geometry with parallel shotlines orthogonal to parallel receiver lines) is to ensure that the maximum cross‐line offset is equal to the maximum inline offset. Three‐dimensional symmetric sampling simplifies the design of 3-D acquisition geometries. A simple checklist of geophysical requirements (spatial continuity, resolution, mappability of shallow and deep objectives, and signal‐to‐noise ratio) limits the choice of survey parameters. In these consideration, offset and azimuth distributions are implicitly being taken care of. The implementation in the field requires careful planning to prevent loss of spatial continuity.

scholarly journals Multisegment Scheme Applications to Modified Chebyshev Picard Iteration Method for Highly Elliptical Orbits

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Donghoon Kim ◽  
John L. Junkins ◽  
James D. Turner
Keyword(s):  
Iteration Method ◽  
Initial Boundary ◽  
Picard Iteration ◽  
True Anomaly ◽  
Multiple Time ◽  
Data Sampling ◽  
Initial Boundary Value Problems ◽  
Initial Boundary Value ◽  
The Given ◽  
Dense Sampling

A modified Chebyshev Picard iteration method is proposed for solving orbit propagation initial/boundary value problems. Cosine sampling techniques, known as Chebyshev-Gauss-Lobatto (CGL) nodes, are used to reduce Runge’s phenomenon that plagues many series approximations. The key benefit of using the CGL data sampling is that the nodal points are distributed nonuniformly, with dense sampling at the beginning and ending times. This problem can be addressed by a nonlinear time transformation and/or by utilizing multiple time segments over an orbit. This paper suggests a method, called a multisegment method, to obtain accurate solutions overall regardless of initial states and albeit eccentricity by dividing the given orbit into two or more segments based on the true anomaly.

scholarly journals Machining precision controlling method for plane surface assisted by SPDT

2021 ◽  
Vol 30 ◽  
pp. 263498332199550
Author(s):  
Jingjin Li ◽  
Shijun Ji ◽  
Ji Zhao ◽  
Fei Yuan ◽  
Handa Dai
Keyword(s):  
Surface Topography ◽  
Plane Surface ◽  
Single Point ◽  
Processing System ◽  
Maximum Deviation ◽  
Slow Tool Servo ◽  
Surface Precision ◽  
Traditional Processing ◽  
The Given ◽  
Precision Part

In traditional processing mode, a given lathe and a set of fixed processing system can only produce a predetermined precision part. This article proposes a machining method that can control the surface precision of machining plane parts, and four gaskets with different accuracy requirements are processed on the same slow tool servo single-point diamond lathe for experimental verification. Then, the Peak Village (PV) value and surface topography of the processed parts were measured using the surface profiler Taylor Hobson PGI 1240 and Keyence VR-3200, respectively. Through the processing and analysis of the measured data, the maximum deviation between the PV value and the given PV value is 2.4 µm, the minimum deviation is 0.4 µm. And the PV value obtained by calculating the helical spacing measured by surface topography according to the method in this article is approximately equal to the measured PV value, so the correctness of the machining method is verified. Therefore, the machining method can control the surface accuracy of machining parts accurately according to the required accuracy.

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