; OPOh+'0HP
$TU Delft Repository search results0TU Delft Repository search results (max. 1000)TU Delft LibraryTU Delft Library@d#V@d#V՜.+,0HPX`hp
x
WorksheetFeuilles de calcul
B=%r8X"1Calibri1Calibri1Calibri1
Calibri 83ffff̙̙3f3fff3f3f33333f33333.J=TU Delft Repositoryg ?uuidrepository linktitleauthorcontributorpublication yearabstract
subject topiclanguagepublication type publisherisbnissnpatent
patent statusbibliographic noteaccess restrictionembargo datefaculty
departmentresearch group programmeprojectcoordinates)uuid:fcc45eb06b1b47cc9952c469fbcf795dDhttp://resolver.tudelft.nl/uuid:fcc45eb06b1b47cc9952c469fbcf795dqPerformance and scalability of finitedifference and finiteelement wavepropagation modeling on Intel's Xeon Phi3Zhebel, E.; Minisini, S.; Kononov, A.; Mulder, W.A."With the rapid developments in parallel compute architectures, algorithms for seismic modeling and imaging need to be reconsidered in terms of parallelization. The aim of this paper is to compare scalability of seismic modeling algorithms: finite differences, continuous masslumped finite elements and discontinuous Galerkin finite elements. The performance for these methods is considered for a given accuracy. The experiments were performed on an Intel Sandy Bridge dual 8core machine and on Intel's 61core Xeon Phi, which is based on the Many Integrated Core architecture. The codes ran without any modifications. On the Sandy Bridge, the scalability is similar for all methods. On the Xeon Phi, the finite elements outperform finite differences on larger number of cores in terms of scalability.A3D; acoustic; finite difference; finite element; wave propagationenjournal article$Society of Exploration Geophysicists!Civil Engineering and GeosciencesGeoscience & Engineering)uuid:00c70b23d887465aa25a72dae2d024cbDhttp://resolver.tudelft.nl/uuid:00c70b23d887465aa25a72dae2d024cbiLocal time stepping with the discontinuous Galerkin method for wave propagation in 3D heterogeneous media3Minisini, S.; Zhebel, E.; Kononov, A.; Mulder, W.A.Modeling and imaging techniques for geophysics are extremely demanding in terms of computational resources. Seismic data attempt to resolve smaller scales and deeper targets in increasingly more complex geologic settings. Finite elements enable accurate simulation of timedependent wave propagation in heterogeneous media. They are more costly than finitedifference methods, but this is compensated by their superior accuracy if the finiteelement mesh follows the sharp impedance contrasts and by their improved efficiency if the element size scales with wavelength, hence with the local wave velocity. However, 3D complex geologic settings often contain details on a very small scale compared to the dominant wavelength, requiring the mesh to contain elements that are smaller than dictated by the wavelength. Also, limitations of the mesh generation software may produce regions where the elements are much smaller than desired. In both cases, this leads to a reduction of the time step required to solve the wave propagation and significantly increases the computational cost. Local time stepping (LTS) can improve the computational efficiency and speed up the simulation. We evaluated a local formulation of an LTS scheme with secondorder accuracy for the discontinuous Galerkin finiteelement discretization of the wave equation.We tested the benefits of the scheme by considering a geologic model for a NorthSeatype example.73D; acoustic; wave equation; modeling; wave propagation)uuid:c45304e8b3df4a0ea95ad998235a51a1Dhttp://resolver.tudelft.nl/uuid:c45304e8b3df4a0ea95ad998235a51a1TA Comparison of Continuous Masslumped Finite Elements and Finite Differences for 3D5The finitedifference method is widely used for timedomain modelling of the wave equation because of its ease of implementation of highorder spatial discretization schemes, parallelization and computational efficiency. However, finite elements on tetrahedral meshes are more accurate in complex geometries near sharp interfaces. We compared the fourthorder finitedifference method to fourthorder continuous masslumped finite elements in terms of accuracy and computational cost. The results show that for simple models like a cube with constant density and velocity, the finitedifference met<Shod outperforms the finiteelement method by at least an order of magnitude. For a model with interior complexity and topography, however, the finite elements are about two orders of magnitude faster than finite differences.conference paperEAGE)uuid:352f744379894ce78cfcc235616aa72fDhttp://resolver.tudelft.nl/uuid:352f744379894ce78cfcc235616aa72fA comparison of explicit continuous and discontinuous Galerkin methods and finite differences for wave propagation in 3D heterogeneous media3Minisini, S.; Mulder, W.A.; Zhebel, E.; Kononov, A.Abstract only.Whighorder continuous; discontinuous finite elements; masslumping; heterogeneous mediaVienna University of Technology)uuid:a5077cbf4fe24560a4244bbf47f732a8Dhttp://resolver.tudelft.nl/uuid:a5077cbf4fe24560a4244bbf47f732a84A 3D Tetrahedral Mesh Generator for Seismic Problems3Kononov, A.; Minisini, S.; Zhebel, E.; Mulder, W.A.Finiteelement modelling of seismic wave propagation on tetrahedra requires meshes that accurately follow interfaces between impedance contrasts or surface topography and have element sizes proportional to the local velocity. We explain a mesh generation approach by example. Starting from a finitedifference representation of the velocity model, triangulated surfaces are generated along impedance discontinuities. These define subdomains that are meshed independently and in parallel, honouring the local velocity values. The resulting volumetric meshes are merged into a single mesh. The approach is flexible, efficient, scalable and capable of producing quality meshes.)uuid:a2c15842bd6949e0992b18060dc49f2eDhttp://resolver.tudelft.nl/uuid:a2c15842bd6949e0992b18060dc49f2esEfficiency Comparison for Continuous Masslumped and Discontinuous Galerkin Finiteelements for 3D Wave PropagationThe spreading adoption of computationally intensive techniques such as Reverse Time Migration and Full Waveform Inversion increases the need of efficiently solving the threedimensional wave equation. Common finitedifference discretization schemes lose their accuracy and efficiency in complex geological settings with discontinuities in the material properties and topography. Finite elements on tetrahedral meshes follow the interfaces while maintaining their accuracy and can have smaller meshes if the elements are scaled with the velocity. Here, we consider two higherorder finite element methods that allow for explicit time stepping: the continuous masslumped finiteelement method (CMLFE) and the symmetric interior penalty discontinuous Galerkin method (SIPDG). The price paid for the ability to perform explicit time stepping is an increase in computational cost: CMLFE requires a larger number of discretization nodes to preserve accuracy, whereas SIPDG needs additional fluxes to impose the continuity of the solution. Therefore, it is not obvious which one is more efficient. We compare the two methods in terms of accuracy, stability and computational cost. Experiments on a threedimensional problem with a dipping interface show that CMLFE and SIPDG have similar stability conditions, accuracy and efficiency, the last being measured as the computational time required to reach a given accuracy of the result.
*+&ffffff?'ffffff?(?)?"dXX333333?333333?U}}}}}}}}}} }
}}}
}}}}}}}}}}}}
t@
!
"
#
$
%
&t@
'
(
!
"
)
*
+
p@
,

.
!
"
/
0
1
2p@
3
4

5
!
"
6
7
8
9p@
:

.
!
"
;
<
=
&p@
>

!
"
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~>@ddyKyKhttp://resolver.tudelft.nl/uuid:fcc45eb06b1b47cc9952c469fbcf795dyKyKhttp://resolver.tudelft.nl/uuid:00c70b23d887465aa25a72dae2d024cbyKyKhttp://resolver.tudelft.nl/uuid:c45304e8b3df4a0ea95ad998235a51a1yKyKhttp://resolver.tudelft.nl/uuid:352f744379894ce78cfcc235616aa72fyKyKhttp://resolver.tudelft.nl/uuid:a5077cbf4fe24560a4244bbf47f732a8yKyKhttp://resolver.tudelft.nl/uuid:a2c15842bd6949e0992b18060dc49f2egg
Root Entry Fd#Vd#V@SummaryInformation( F<Workbook FDocumentSummaryInformation8 F
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMN