The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform

Sylvain Louvet - One of the best experts on this subject based on the ideXlab platform.

Louvet Sylvain - One of the best experts on this subject based on the ideXlab platform.

Rosario López - One of the best experts on this subject based on the ideXlab platform.

  • Revisiting the border between Newtonian Mechanics and General Relativity: The periastron advance
    Institute for Catalan Studies, 2015
    Co-Authors: Joaquim A. Batlle, Rosario López
    Abstract:

    The problem of periastron advance, which is the basis of one of the three classical tests of relativity theory, is revised with respect to both Newtonian Mechanics and General Relativity and updated in the light of recent astronomical measurements of binary pulsars. We show that in Newtonian Mechanics the addition of a corrective term to Newton’s law of gravitation, consistent with the principles of Newtonian Mechanics, leads to the same formula of periastron advance as that used in General Relativity, which proves to be valid in all astronomical cases known, even in the cases of binary pulsars such as PSR B1913+16, PSR J1141-6545 and the so-called double pulsar PSR J0737-3039A and PSR J0737-3039B, which are considered as natural relativity laboratories. Thus, among the relativistic phenomena, the periastron advance is one that can be also understood in Newtonian terms by means of an ad hoc assumption. Keywords: periastron · perihelion · gravitation · pulsar · Newtonian Mechanic

Nicholas P. Baileyandjacob Schiøtz - One of the best experts on this subject based on the ideXlab platform.

  • An InteratomicPotentialfor Studying CuZrBulkMetallicGlasses
    2007
    Co-Authors: Byanca Paduraru, Abder Kenoufi, Nicholas P. Baileyandjacob Schiøtz
    Abstract:

    BMGs are remarkably different from the ones of ordinary metallic alloys due to the atomic level disorder in the glassy state. Unlike crystalline materials plastic deformation in metallic glasses cannot be caused by lattice defects but takes place through atomic-scale deformation events and may furthermore involve localization through formation of shear bands. For understanding the origin of their Mechanical properties it is important to get the basic understanding of fundamental theoretical problems through atomistic simulations. Molecular dynamics (MD) treats atomic systems according to Newtonian Mechanic laws. Atoms are point particles, interacting through an interatomic potential, describing the energy of an atom as a function of the positions of all atoms in a neighboring region of space. The time evolution of the system is obtained by numerically integrating Newton’s second law. Often the interatomic potential is a classical potential, no quantum Mechanical description of the material is attempted, but the functional form of the potential may be derived from quantum Mechanical arguments. [9] MD is able to treat systems with millions of atoms, and permits the average calculations of transport (diffusion, thermal conductivities, viscosity), or Mechanical quantities (elastic constant, plastic yield), and also the modeling of complex phenomena (shear band localization, fracture appearance, neutronic cascades). The quality of the results will depend on the quality of the interatomic potential, simple potentials giving a less accurate description of the interatomic interactions while allowing very large simulations, more complicated potentials may give a better description of the interaction, but limit the simulation size. Many-body potentials such as the Embedded Atom Method [10] and the Effective Medium Theory (EMT) [11,12] have been shown to give a good description of the late transition metals crystallizing in close-packed structures, and their alloys, while still allowing simulations with millions of atoms. [13] In this paper, we create an EMT potential optimized for modeling the Mechanical and thermodynamic properties of CuZr bulk metallic glass. CuZr was recently discovered to be a binary bulk metallic glass. [6,14] Since binary alloys are easier to model than alloys with more elements, this makes CuZr an attractive bulk metallic glass to study theoretically. Previously, an interatomic force field has been fitted to CuZr by Duan et al., [28] but we find that the EMT force field described here provides a better description of the structure of the metallic glass. The potential developed here will be used to model the Mechanical properties of CuZr, to be published elsewhere.

Abder Kenoufi - One of the best experts on this subject based on the ideXlab platform.

  • An Interatomic Potential for Studying CuZr Bulk Metallic Glasses
    Advanced Engineering Materials, 2007
    Co-Authors: Anco Paduraru, Abder Kenoufi, Nicholas P. Bailey, Jacob Schiøtz
    Abstract:

    Binary alloys capable of forming metallic glasses have been discovered recently. The Mechanical properties of BMGs are remarkably different from the ones of ordinary metallic alloys due to the atomic level disorder in the glassy state. Unlike crystalline materials plastic deformation in metallic glasses cannot be caused by lattice defects but takes place through atomic-scale deformation events and may furthermore involve localization through formation of shear bands. For understanding the origin of their Mechanical properties it is important to get the basic understanding of fundamental theoretical problems through atomistic simulations. Molecular dynamics (MD) treats atomic systems according to Newtonian Mechanic laws. Atoms are point particles, interacting through an interatomic potential, describing the energy of an atom as a function of the positions of all atoms in a neighboring region of space. The time evolution of the system is obtained by numerically integrating Newton’s second law. Often the interatomic potential is a classical potential, no quantum Mechanical description of the material is attempted, but the functional form of the potential may be derived from quantum Mechanical arguments. MD is able to treat systems with millions of atoms, and permits the average calculations of transport (diffusion, thermal conductivities, viscosity), or Mechanical quantities (elastic constant, plastic yield), and also the modeling of complex phenomena (shear band localization, fracture appearance, neutronic cascades). The quality of the results will depend on the quality of the interatomic potential, simple potentials giving a less accurate description of the interatomic interactions while allowing very large simulations, more complicated potentials may give a better description of the interaction, but limit the simulation size. Many-body potentials such as the Embedded Atom Method and the Effective Medium Theory (EMT) have been shown to give a good description of the late transition metals crystallizing in close-packed structures, and their alloys, while still allowing simulations with millions of atoms. In this paper, we create an EMT potential optimized for modeling the Mechanical and thermodynamic properties of CuZr bulk metallic glass. CuZr was recently discovered to be a binary bulk metallic glass. Since binary alloys are easier to model than alloys with more elements, this makes CuZr an attractive bulk metallic glass to study theoretically. Previously, an interatomic force field has been fitted to CuZr by Duan et al., but we find that the EMT force field described here provides a better description of the structure of the metallic glass. The potential developed here will be used to model the Mechanical properties of CuZr, to be published elsewhere.

  • An InteratomicPotentialfor Studying CuZrBulkMetallicGlasses
    2007
    Co-Authors: Byanca Paduraru, Abder Kenoufi, Nicholas P. Baileyandjacob Schiøtz
    Abstract:

    BMGs are remarkably different from the ones of ordinary metallic alloys due to the atomic level disorder in the glassy state. Unlike crystalline materials plastic deformation in metallic glasses cannot be caused by lattice defects but takes place through atomic-scale deformation events and may furthermore involve localization through formation of shear bands. For understanding the origin of their Mechanical properties it is important to get the basic understanding of fundamental theoretical problems through atomistic simulations. Molecular dynamics (MD) treats atomic systems according to Newtonian Mechanic laws. Atoms are point particles, interacting through an interatomic potential, describing the energy of an atom as a function of the positions of all atoms in a neighboring region of space. The time evolution of the system is obtained by numerically integrating Newton’s second law. Often the interatomic potential is a classical potential, no quantum Mechanical description of the material is attempted, but the functional form of the potential may be derived from quantum Mechanical arguments. [9] MD is able to treat systems with millions of atoms, and permits the average calculations of transport (diffusion, thermal conductivities, viscosity), or Mechanical quantities (elastic constant, plastic yield), and also the modeling of complex phenomena (shear band localization, fracture appearance, neutronic cascades). The quality of the results will depend on the quality of the interatomic potential, simple potentials giving a less accurate description of the interatomic interactions while allowing very large simulations, more complicated potentials may give a better description of the interaction, but limit the simulation size. Many-body potentials such as the Embedded Atom Method [10] and the Effective Medium Theory (EMT) [11,12] have been shown to give a good description of the late transition metals crystallizing in close-packed structures, and their alloys, while still allowing simulations with millions of atoms. [13] In this paper, we create an EMT potential optimized for modeling the Mechanical and thermodynamic properties of CuZr bulk metallic glass. CuZr was recently discovered to be a binary bulk metallic glass. [6,14] Since binary alloys are easier to model than alloys with more elements, this makes CuZr an attractive bulk metallic glass to study theoretically. Previously, an interatomic force field has been fitted to CuZr by Duan et al., [28] but we find that the EMT force field described here provides a better description of the structure of the metallic glass. The potential developed here will be used to model the Mechanical properties of CuZr, to be published elsewhere.