4 research outputs found
Optimisation et parallĂšlisation de la mĂ©thode des Ă©lements frontiĂšres pour lâĂ©quation des ondes dans le domaine temporel
The time-domain BEM for the wave equation in acoustics and electromagnetism is used to simulatethe propagation of a wave with a discretization in time. It allows to obtain several frequencydomainresults with one solve. In this thesis, we investigate the implementation of an efficientTD-BEM solver using different approaches. We describe the context of our study and the TD-BEMformulation expressed as a sparse linear system composed of multiple interaction/convolutionmatrices. This system is naturally computed using the sparse matrix-vector product (SpMV). Wework on the limits of the SpMV kernel by looking at the matrix reordering and the behavior of ourSpMV kernels using vectorization (SIMD) on CPUs and an advanced blocking-layout on NvidiaGPUs. We show that this operator is not appropriate for our problem, and we then propose toreorder the original computation to get a special matrix structure. This new structure is called aslice matrix and is computed with a custom matrix/vector product operator. We present an optimizedimplementation of this operator on CPUs and Nvidia GPUs for which we describe advancedblocking schemes. The resulting solver is parallelized with a hybrid strategy above heterogeneousnodes and relies on a new heuristic to balance the work among the processing units. Due tothe quadratic complexity of this matrix approach, we study the use of the fast multipole method(FMM) for our time-domain BEM solver. We investigate the parallelization of the general FMMalgorithm using several paradigms in both shared and distributed memory, and we explain howmodern runtime systems are well-suited to express the FMM computation. Finally, we investigatethe implementation and the parametrization of an FMM kernel specific to our TD-BEM, and weprovide preliminary results.La mĂ©thode des Ă©lĂ©ments frontiĂšres pour lâĂ©quation des ondes (BEM) est utilisĂ©e en acoustique eten Ă©lectromagnĂ©tisme pour simuler la propagation dâune onde avec une discrĂ©tisation en temps(TD). Elle permet dâobtenir un rĂ©sultat pour plusieurs frĂ©quences Ă partir dâune seule rĂ©solution.Dans cette thĂšse, nous nous intĂ©ressons Ă lâimplĂ©mentation efficace dâun simulateur TD-BEM sousdiffĂ©rents angles. Nous dĂ©crivons le contexte de notre Ă©tude et la formulation utilisĂ©e qui sâexprimesous la forme dâun systĂšme linĂ©aire composĂ© de plusieurs matrices dâinteractions/convolutions.Ce systĂšme est naturellement calculĂ© en utilisant lâopĂ©rateur matrice/vecteur creux (SpMV). Nousavons travaillĂ© sur la limite du SpMV en Ă©tudiant la permutation des matrices et le comportementde notre implĂ©mentation aidĂ© par la vectorisation sur CPU et avec une approche par bloc surGPU. Nous montrons que cet opĂ©rateur nâest pas appropriĂ© pour notre problĂšme et nous proposonsde changer lâordre de calcul afin dâobtenir une matrice avec une structure particuliĂšre.Cette nouvelle structure est appelĂ©e une matrice tranche et se calcule Ă lâaide dâun opĂ©rateur spĂ©cifique.Nous dĂ©crivons des implĂ©mentations optimisĂ©es sur architectures modernes du calculhaute-performance. Le simulateur rĂ©sultant est parallĂ©lisĂ© avec une approche hybride (mĂ©moirespartagĂ©es/distribuĂ©es) sur des noeuds hĂ©tĂ©rogĂšnes, et se base sur une nouvelle heuristique pourĂ©quilibrer le travail entre les processeurs. Cette approche matricielle a une complexitĂ© quadratiquesi bien que nous avons Ă©tudiĂ© son accĂ©lĂ©ration par la mĂ©thode des multipoles rapides (FMM). Nousavons tout dâabord travaillĂ© sur la parallĂ©lisation de lâalgorithme de la FMM en utilisant diffĂ©rentsparadigmes et nous montrons comment les moteurs dâexĂ©cution sont adaptĂ©s pour relĂącher le potentielde la FMM. Enfin, nous prĂ©sentons des rĂ©sultats prĂ©liminaires dâun simulateur TD-BEMaccĂ©lĂ©rĂ© par FMM
Proceedings. 9th 3DGeoInfo Conference 2014, [11-13 November 2014, Dubai]
It is known that, scientific disciplines such as geology, geophysics, and reservoir exploration intrinsically use 3D geo-information in their models and simulations. However, 3D geo-information is also urgently needed in many traditional 2D planning areas such as civil engineering, city and infrastructure modeling, architecture, environmental planning etc. Altogether, 3DGeoInfo is an emerging technology that will greatly influence the market within the next few decades. The 9th International 3DGeoInfo Conference aims at bringing together international state-of-the-art researchers and practitioners facilitating the dialogue on emerging topics in the field of 3D geo-information. The conference in Dubai offers an interdisciplinary forum of sub- and above-surface 3D geo-information researchers and practitioners dealing with data acquisition, modeling, management, maintenance, visualization, and analysis of 3D geo-information