The Experts below are selected from a list of 77022 Experts worldwide ranked by ideXlab platform
Christian D Ott - One of the best experts on this subject based on the ideXlab platform.
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a new Open Source Code for spherically symmetric stellar collapse to neutron stars and black holes
Classical and Quantum Gravity, 2010Co-Authors: Evan Oconnor, Christian D OttAbstract:We present the new Open-Source spherically symmetric general-relativistic (GR) hydrodynamics Code GR1D. It is based on the Eulerian formulation of GR hydrodynamics (GRHD) put forth by Romero–Ibanez–Gourgoulhon and employs radial-gauge, polar-slicing coordinates in which the 3+1 equations simplify substantially. We discretize the GRHD equations with a finite-volume scheme, employing piecewise-parabolic reconstruction and an approximate Riemann solver. GR1D is intended for the simulation of stellar collapse to neutron stars and black holes and will also serve as a testbed for modeling technology to be incorporated in multi-D GR Codes. Its GRHD part is coupled to various finite-temperature microphysical equations of state in tabulated form that we make available with GR1D. An approximate deleptonization scheme for the collapse phase and a neutrino-leakage/heating scheme for the postbounce epoch are included and described. We also derive the equations for effective rotation in 1D and implement them in GR1D. We present an array of standard test calculations and also show how simple analytic equations of state in combination with presupernova models from stellar evolutionary calculations can be used to study qualitative aspects of black hole formation in failing rotating core-collapse supernovae. In addition, we present a simulation with microphysical equations of state and neutrino leakage/heating of a failing core-collapse supernova and black hole formation in a presupernova model of a 40 M_⊙ zero-age main-sequence star. We find good agreement on the time of black hole formation (within 20%) and last stable protoneutron star mass (within 10%) with predictions from simulations with full Boltzmann neutrino radiation hydrodynamics.
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a new Open Source Code for spherically symmetric stellar collapse to neutron stars and black holes
arXiv: High Energy Astrophysical Phenomena, 2009Co-Authors: Evan Oconnor, Christian D OttAbstract:We present the new Open-Source spherically-symmetric general-relativistic (GR) hydrodynamics Code GR1D. It is based on the Eulerian formulation of GR hydrodynamics (GRHD) put forth by Romero-Ibanez-Gourgoulhon and employs radial-gauge, polar-slicing coordinates in which the 3+1 equations simplify substantially. We discretize the GRHD equations with a finite-volume scheme, employing piecewise-parabolic reconstruction and an approximate Riemann solver. GR1D is intended for the simulation of stellar collapse to neutron stars and black holes and will also serve as a testbed for modeling technology to be incorporated in multi-D GR Codes. Its GRHD part is coupled to various finite-temperature microphysical equations of state in tabulated form that we make available with GR1D. An approximate deleptonization scheme for the collapse phase and a neutrino-leakage/heating scheme for the postbounce epoch are included and described. We also derive the equations for effective rotation in 1D and implement them in GR1D. We present an array of standard test calculations and also show how simple analytic equations of state in combination with presupernova models from stellar evolutionary calculations can be used to study qualitative aspects of black hole formation in failing rotating core-collapse supernovae. In addition, we present a simulation with microphysical EOS and neutrino leakage/heating of a failing core-collapse supernova and black hole formation in a presupernova model of a 40 solar mass zero-age main-sequence star. We find good agreement on the time of black hole formation (within 20%) and last stable protoneutron star mass (within 10%) with predictions from simulations with full Boltzmann neutrino radiation hydrodynamics.
Jeremy E Kozdon - One of the best experts on this subject based on the ideXlab platform.
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large eddy simulations with climatemachine v0 2 0 a new Open Source Code for atmospheric simulations on gpus and cpus
Geoscientific Model Development Discussions, 2021Co-Authors: Akshay Sridhar, Yassine Tissaoui, Simone Marras, Zhaoyi Shen, Charles Kawczynski, Simon Byrne, Kiran Pamnany, Maciej Waruszewski, Thomas H Gibson, Jeremy E KozdonAbstract:Abstract. We introduce ClimateMachine, a new Open-Source atmosphere modeling framework using the Julia language to be performance portable on central processing units (CPUs) and graphics processing units (GPUs). ClimateMachine uses a common framework both for coarser-resolution global simulations and for high-resolution, limited-area large-eddy simulations (LES). Here, we demonstrate the LES configuration of the atmosphere model in canonical benchmark cases and atmospheric flows, using an energy-conserving nodal discontinuous-Galerkin (DG) discretization of the governing equations. Resolution dependence, conservation characteristics and scaling metrics are examined in comparison with existing LES Codes. They demonstrate the utility of ClimateMachine as a modelling tool for limited-area LES flow configurations.
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large eddy simulations with climatemachine a new Open Source Code for atmospheric simulations on gpus and cpus
arXiv: Atmospheric and Oceanic Physics, 2021Co-Authors: Akshay Sridhar, Yassine Tissaoui, Simone Marras, Zhaoyi Shen, Charles Kawczynski, Simon Byrne, Kiran Pamnany, Maciej Waruszewski, Thomas H Gibson, Jeremy E KozdonAbstract:We introduce ClimateMachine, a new Open-Source atmosphere modeling framework using the Julia language to be performance portable on central processing units (CPUs) and graphics processing units (GPUs). ClimateMachine uses a common framework both for coarser-resolution global simulations and for high-resolution, limited-area large-eddy simulations (LES). Here, we demonstrate the LES configuration of the atmosphere model in canonical benchmark cases and atmospheric flows, using an energy-conserving nodal discontinuous-Galerkin (DG) discretization of the governing equations. Resolution dependence, conservation characteristics and scaling metrics are examined in comparison with existing LES Codes. They demonstrate the utility of ClimateMachine as a modelling tool for limited-area LES flow configurations.
Cristina V Lopes - One of the best experts on this subject based on the ideXlab platform.
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Sourcerer an infrastructure for large scale collection and analysis of Open Source Code
Science of Computer Programming, 2014Co-Authors: Sushil Bajracharya, Joel Ossher, Cristina V LopesAbstract:A large amount of Open Source Code is now available online, presenting a great potential reSource for software developers. This has motivated software engineering researchers to develop tools and techniques to allow developers to reap the benefits of these billions of lines of Source Code. However, collecting and analyzing such a large quantity of Source Code presents a number of challenges. Although the current generation of Open Source Code search engines provides access to the Source Code in an aggregated repository, they generally fail to take advantage of the rich structural information contained in the Code they index. This makes them significantly less useful than Sourcerer for building state-of-the-art software engineering tools, as these tools often require access to both the structural and textual information available in Source Code. We have developed Sourcerer, an infrastructure for large-scale collection and analysis of Open Source Code. By taking full advantage of the structural information extracted from Source Code in its repository, Sourcerer provides a foundation upon which state-of-the-art search engines and related tools can easily be built. We describe the Sourcerer infrastructure, present the applications that we have built on top of it, and discuss how existing tools could benefit from using Sourcerer.
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Sourcerer a search engine for Open Source Code supporting structure based search
Conference on Object-Oriented Programming Systems Languages and Applications, 2006Co-Authors: Sushil Bajracharya, Paul Rigor, Erik Linstead, Pierre Baldi, Cristina V LopesAbstract:We present Sourcerer, a search engine for Open-Source Code. Sourcerer extracts fine-grained structural information from the Code and stores it in a relational model. This information is used to implement a basic notion of CodeRank and to enable search forms that go beyond conventional keyword-based searches.
Akshay Sridhar - One of the best experts on this subject based on the ideXlab platform.
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large eddy simulations with climatemachine v0 2 0 a new Open Source Code for atmospheric simulations on gpus and cpus
Geoscientific Model Development Discussions, 2021Co-Authors: Akshay Sridhar, Yassine Tissaoui, Simone Marras, Zhaoyi Shen, Charles Kawczynski, Simon Byrne, Kiran Pamnany, Maciej Waruszewski, Thomas H Gibson, Jeremy E KozdonAbstract:Abstract. We introduce ClimateMachine, a new Open-Source atmosphere modeling framework using the Julia language to be performance portable on central processing units (CPUs) and graphics processing units (GPUs). ClimateMachine uses a common framework both for coarser-resolution global simulations and for high-resolution, limited-area large-eddy simulations (LES). Here, we demonstrate the LES configuration of the atmosphere model in canonical benchmark cases and atmospheric flows, using an energy-conserving nodal discontinuous-Galerkin (DG) discretization of the governing equations. Resolution dependence, conservation characteristics and scaling metrics are examined in comparison with existing LES Codes. They demonstrate the utility of ClimateMachine as a modelling tool for limited-area LES flow configurations.
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large eddy simulations with climatemachine a new Open Source Code for atmospheric simulations on gpus and cpus
arXiv: Atmospheric and Oceanic Physics, 2021Co-Authors: Akshay Sridhar, Yassine Tissaoui, Simone Marras, Zhaoyi Shen, Charles Kawczynski, Simon Byrne, Kiran Pamnany, Maciej Waruszewski, Thomas H Gibson, Jeremy E KozdonAbstract:We introduce ClimateMachine, a new Open-Source atmosphere modeling framework using the Julia language to be performance portable on central processing units (CPUs) and graphics processing units (GPUs). ClimateMachine uses a common framework both for coarser-resolution global simulations and for high-resolution, limited-area large-eddy simulations (LES). Here, we demonstrate the LES configuration of the atmosphere model in canonical benchmark cases and atmospheric flows, using an energy-conserving nodal discontinuous-Galerkin (DG) discretization of the governing equations. Resolution dependence, conservation characteristics and scaling metrics are examined in comparison with existing LES Codes. They demonstrate the utility of ClimateMachine as a modelling tool for limited-area LES flow configurations.
Sushil Bajracharya - One of the best experts on this subject based on the ideXlab platform.
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Sourcerer an infrastructure for large scale collection and analysis of Open Source Code
Science of Computer Programming, 2014Co-Authors: Sushil Bajracharya, Joel Ossher, Cristina V LopesAbstract:A large amount of Open Source Code is now available online, presenting a great potential reSource for software developers. This has motivated software engineering researchers to develop tools and techniques to allow developers to reap the benefits of these billions of lines of Source Code. However, collecting and analyzing such a large quantity of Source Code presents a number of challenges. Although the current generation of Open Source Code search engines provides access to the Source Code in an aggregated repository, they generally fail to take advantage of the rich structural information contained in the Code they index. This makes them significantly less useful than Sourcerer for building state-of-the-art software engineering tools, as these tools often require access to both the structural and textual information available in Source Code. We have developed Sourcerer, an infrastructure for large-scale collection and analysis of Open Source Code. By taking full advantage of the structural information extracted from Source Code in its repository, Sourcerer provides a foundation upon which state-of-the-art search engines and related tools can easily be built. We describe the Sourcerer infrastructure, present the applications that we have built on top of it, and discuss how existing tools could benefit from using Sourcerer.
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Sourcerer a search engine for Open Source Code supporting structure based search
Conference on Object-Oriented Programming Systems Languages and Applications, 2006Co-Authors: Sushil Bajracharya, Paul Rigor, Erik Linstead, Pierre Baldi, Cristina V LopesAbstract:We present Sourcerer, a search engine for Open-Source Code. Sourcerer extracts fine-grained structural information from the Code and stores it in a relational model. This information is used to implement a basic notion of CodeRank and to enable search forms that go beyond conventional keyword-based searches.
