The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform

Kenneth Chiu - One of the best experts on this subject based on the ideXlab platform.

  • CCGRID - Automatic Performance Prediction for Load-Balancing Coupled Models
    2013 13th IEEE ACM International Symposium on Cluster Cloud and Grid Computing, 2013
    Co-Authors: J. W. Larson, Kenneth Chiu
    Abstract:

    Computationally-demanding, parallel coupled Models are crucial to understanding many important multi-physics/multiscale phenomena. Load-balancing such simulation son large clusters is often done through off-line, static means that often require significant manual input. Dynamic, runtime load-balancing has been shown in our previous work to be effective, but we still used a manually generated performance predictor to guide the load-balancing decisions. In this paper, we show how timing and interaction information obtained by instrumenting the middleware can be used to automatically generate a performance predictor that relates the overall execution time to the execution time of each individual sub Model. The performance predictor is evaluated through the new coupled Model Benchmark employing five constituent sub Models that simulates the CCSM coupled climate Model.

  • ISPA - Dynamic Load Balancing for Malleable Model Coupling
    2012 IEEE 10th International Symposium on Parallel and Distributed Processing with Applications, 2012
    Co-Authors: J. Walter Larson, Kenneth Chiu
    Abstract:

    Dynamic load balancing both within and between constituent subsystems is required to achieve ultra scalability in coupled multi physics and multi scale Models. Inter constituent dynamic load balancing requires runtime resizing -- or malleability -- of subsystem processing element (PE) cohorts. In our previous work, we developed and introduced the Malleable Model Coupling Toolkit with a load balance manager implementing and providing a runtime load-balancing algorithm using PE reallocation across subsystems. In this paper, we extend that work by adding the ability to adapt to coupled Models that have changing loads during execution. We evaluate the algorithm through a synthetic coupled-Model Benchmark that uses the LogP performance Model as applied to parallel LU decomposition.

D. Seyedi - One of the best experts on this subject based on the ideXlab platform.

  • transverse action a Model Benchmark exercise for numerical analysis of the callovo oxfordian claystone hydromechanical response to excavation operations
    Computers and Geotechnics, 2017
    Co-Authors: D. Seyedi, Gilles Armand, A. Noiret
    Abstract:

    Abstract The Callovo-Oxfordian claystone (COx) is considered as a potential geological formation to host an industrial radioactive waste repository in France. A detailed understanding of the thermo-hydro-mechanical (THM) behavior of the COx is a key issue for design of different repository structures and the safety calculations of the project. More particularly, numerical Modeling of induced fracture networks around drifts excavated at the main level of the Andra’s Meuse/Haut-Marne Underground Research Laboratory (M/HM URL) and short and long term behavior of the COx around these drifts are of great interest. Several constitutive Models have been developed/used in the framework of the R&D and simulation programs of Andra. A Model Benchmark exercise has been launched since 2012 to provide an overall view of the developed Models regarding the in situ observations. In this view, two series of test cases, respectively at material point scale and at drift excavation scale are defined. Different kinds of constitutive Models based on the elasto-visco-plasticity concept, continuum damage mechanics, the rigid block spring method and two-scale computational homogenized Model (CHM) are used within this exercise. The obtained results show that accounting for material anisotropy and strain localization treatment techniques can improve the obtained results when elasto-visco-plastic Models are used. Damage mechanics based approaches and methods accounting for discontinuities through discrete elements provide also interesting insights especially when fracturing processes must be Modeled. However, more efforts are necessary to improve the robustness of these kinds of approaches in the complex context of COx response to excavation works.

  • “Transverse Action” – A Model Benchmark exercise for numerical analysis of the Callovo-Oxfordian claystone hydromechanical response to excavation operations
    Computers and Geotechnics, 2017
    Co-Authors: D. Seyedi, Gilles Armand, A. Noiret
    Abstract:

    Abstract The Callovo-Oxfordian claystone (COx) is considered as a potential geological formation to host an industrial radioactive waste repository in France. A detailed understanding of the thermo-hydro-mechanical (THM) behavior of the COx is a key issue for design of different repository structures and the safety calculations of the project. More particularly, numerical Modeling of induced fracture networks around drifts excavated at the main level of the Andra’s Meuse/Haut-Marne Underground Research Laboratory (M/HM URL) and short and long term behavior of the COx around these drifts are of great interest. Several constitutive Models have been developed/used in the framework of the R&D and simulation programs of Andra. A Model Benchmark exercise has been launched since 2012 to provide an overall view of the developed Models regarding the in situ observations. In this view, two series of test cases, respectively at material point scale and at drift excavation scale are defined. Different kinds of constitutive Models based on the elasto-visco-plasticity concept, continuum damage mechanics, the rigid block spring method and two-scale computational homogenized Model (CHM) are used within this exercise. The obtained results show that accounting for material anisotropy and strain localization treatment techniques can improve the obtained results when elasto-visco-plastic Models are used. Damage mechanics based approaches and methods accounting for discontinuities through discrete elements provide also interesting insights especially when fracturing processes must be Modeled. However, more efforts are necessary to improve the robustness of these kinds of approaches in the complex context of COx response to excavation works.

  • A Model Benchmark exercise for numerical analysis of the Callovo-Oxfordian claystone hydromechanical response to excavation operations
    2015
    Co-Authors: D. Seyedi, Gilles Armand, P. Besuelle, F. Collin, S. Cuvilliez, J. Desrues, G. Duveau, A.p. Van Den Eijnden, R. Fernandes, A. Gens
    Abstract:

    The Callovo-Oxfordian claystone (COx) is considered as a potential geological formation to host an industrial radioactive waste repository in France, thanks to its favorable characteristics for radioactive waste containment, as it has a very low hydraulic conductivity, small molecular diffusion and significant retention capacity for radionuclide. A deep understanding of the thermo-hydro-mechanical (THM) behavior of the COx is a key issue for design of different repository structures and the safety calculations of the project. Several constitutive Models have been developed/used in the framework of the R&D and simulation programs of Andra. These Models aim to reproduce the THM behavior of COx under different repository situations and for different structures. A Model Benchmark exercise has been launched since 2012 to provide an overall view of the developed Models, their basic assumptions, their mathematical descriptions, variables and parameters, and to investigate the consequences of these basic assumptions on the calculations results regarding to the experimental observations. Three main constitutive Model families are considered; namely, visco-elasto-plastic Models, damagemechanics based and computational homogenized (CHM) ones. Nine teams using different Models have been participated to this Benchmark exercise.

A. Noiret - One of the best experts on this subject based on the ideXlab platform.

  • transverse action a Model Benchmark exercise for numerical analysis of the callovo oxfordian claystone hydromechanical response to excavation operations
    Computers and Geotechnics, 2017
    Co-Authors: D. Seyedi, Gilles Armand, A. Noiret
    Abstract:

    Abstract The Callovo-Oxfordian claystone (COx) is considered as a potential geological formation to host an industrial radioactive waste repository in France. A detailed understanding of the thermo-hydro-mechanical (THM) behavior of the COx is a key issue for design of different repository structures and the safety calculations of the project. More particularly, numerical Modeling of induced fracture networks around drifts excavated at the main level of the Andra’s Meuse/Haut-Marne Underground Research Laboratory (M/HM URL) and short and long term behavior of the COx around these drifts are of great interest. Several constitutive Models have been developed/used in the framework of the R&D and simulation programs of Andra. A Model Benchmark exercise has been launched since 2012 to provide an overall view of the developed Models regarding the in situ observations. In this view, two series of test cases, respectively at material point scale and at drift excavation scale are defined. Different kinds of constitutive Models based on the elasto-visco-plasticity concept, continuum damage mechanics, the rigid block spring method and two-scale computational homogenized Model (CHM) are used within this exercise. The obtained results show that accounting for material anisotropy and strain localization treatment techniques can improve the obtained results when elasto-visco-plastic Models are used. Damage mechanics based approaches and methods accounting for discontinuities through discrete elements provide also interesting insights especially when fracturing processes must be Modeled. However, more efforts are necessary to improve the robustness of these kinds of approaches in the complex context of COx response to excavation works.

  • “Transverse Action” – A Model Benchmark exercise for numerical analysis of the Callovo-Oxfordian claystone hydromechanical response to excavation operations
    Computers and Geotechnics, 2017
    Co-Authors: D. Seyedi, Gilles Armand, A. Noiret
    Abstract:

    Abstract The Callovo-Oxfordian claystone (COx) is considered as a potential geological formation to host an industrial radioactive waste repository in France. A detailed understanding of the thermo-hydro-mechanical (THM) behavior of the COx is a key issue for design of different repository structures and the safety calculations of the project. More particularly, numerical Modeling of induced fracture networks around drifts excavated at the main level of the Andra’s Meuse/Haut-Marne Underground Research Laboratory (M/HM URL) and short and long term behavior of the COx around these drifts are of great interest. Several constitutive Models have been developed/used in the framework of the R&D and simulation programs of Andra. A Model Benchmark exercise has been launched since 2012 to provide an overall view of the developed Models regarding the in situ observations. In this view, two series of test cases, respectively at material point scale and at drift excavation scale are defined. Different kinds of constitutive Models based on the elasto-visco-plasticity concept, continuum damage mechanics, the rigid block spring method and two-scale computational homogenized Model (CHM) are used within this exercise. The obtained results show that accounting for material anisotropy and strain localization treatment techniques can improve the obtained results when elasto-visco-plastic Models are used. Damage mechanics based approaches and methods accounting for discontinuities through discrete elements provide also interesting insights especially when fracturing processes must be Modeled. However, more efforts are necessary to improve the robustness of these kinds of approaches in the complex context of COx response to excavation works.

J. W. Larson - One of the best experts on this subject based on the ideXlab platform.

  • CCGRID - Automatic Performance Prediction for Load-Balancing Coupled Models
    2013 13th IEEE ACM International Symposium on Cluster Cloud and Grid Computing, 2013
    Co-Authors: J. W. Larson, Kenneth Chiu
    Abstract:

    Computationally-demanding, parallel coupled Models are crucial to understanding many important multi-physics/multiscale phenomena. Load-balancing such simulation son large clusters is often done through off-line, static means that often require significant manual input. Dynamic, runtime load-balancing has been shown in our previous work to be effective, but we still used a manually generated performance predictor to guide the load-balancing decisions. In this paper, we show how timing and interaction information obtained by instrumenting the middleware can be used to automatically generate a performance predictor that relates the overall execution time to the execution time of each individual sub Model. The performance predictor is evaluated through the new coupled Model Benchmark employing five constituent sub Models that simulates the CCSM coupled climate Model.

Patrice Boizumault - One of the best experts on this subject based on the ideXlab platform.

  • Variable neighborhood search for graphical Model energy minimization
    Artificial Intelligence, 2020
    Co-Authors: Abdelkader Ouali, David Allouche, Simon De Givry, Samir Loudni, Yahia Lebbah, Lakhdar Loukil, Patrice Boizumault
    Abstract:

    Graphical Models factorize a global probability distribution/energy function as the product/ sum of local functions. A major inference task, known as MAP in Markov Random Fields and MPE in Bayesian Networks, is to find a global assignment of all the variables with maximum a posteriori probability/minimum energy. A usual distinction on MAP solving methods is complete/incomplete, i.e. the ability to prove optimality or not. Most complete methods rely on tree search, while incomplete methods rely on local search. Among them, we study Variable Neighborhood Search (VNS) for graphical Models. In this paper, we propose an iterative approach above VNS that uses (partial) tree search inside its local neighborhood exploration. The proposed approach performs several neighborhood explorations of increasing search complexity, by controlling two parameters, the discrepancy limit and the neighborhood size. Thus, optimality of the obtained solutions can be proven when the neighborhood size is maximal and with unbounded tree search. We further propose a parallel version of our method improving its anytime behavior on difficult instances coming from a large graphical Model Benchmark. Last we experiment on the challenging minimum energy problem found in Computational Protein Design, showing the practical benefit of our parallel version. A solver is available at https:// github .com /toulbar2 /toulbar2.