The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform
V Gonzalezalvarez - One of the best experts on this subject based on the ideXlab platform.
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stability analysis and passivity properties of a class of thermodynamic processes an Internal Entropy Production approach
Chemical Engineering Science, 2016Co-Authors: J P Garciasandoval, Nicolas Hudon, Denis Dochain, V GonzalezalvarezAbstract:Abstract In this contribution, stability and passivity properties of a class of thermodynamic processes are addressed from a thermodynamical point of view. These thermodynamic processes can be constituted by multiple spatially homogeneous dynamic subsystems modeled by ordinary differential equations. It is shown that the Internal Entropy Production may be used as a Lyapunov function candidate to prove the isolated system stability properties and as a storage function to assess the passivity properties when the system interacts with the surroundings. In addition, it is shown that the stability condition depends on a matrix whose dimension is equal to the number of modeled dynamical phenomena taking place within the system, i.e. the number of phenomena can be smaller than the system dimension. Moreover, a port-controlled Hamiltonian representation of this class of systems based on the Internal Entropy Production is developed. Finally, the theory proposed is applied to three study cases: a heat exchanger, a ideal gas adiabatic chemical reactor and a ideal gas jacketed chemical reactor.
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stability analysis and passivity properties for a class of chemical reactors Internal Entropy Production approach
Computers & Chemical Engineering, 2015Co-Authors: J P Garciasandoval, V Gonzalezalvarez, C. CalderónAbstract:In this contribution, the stability and passivity properties of a class of chemical reactors are addressed from a thermodynamical point of view. For this purpose, a thermodynamical consistent model is derived from a generic gas reactor model whose rate is based on the reaction progress at the mesoscopic scale. It is shown that the Internal Entropy Production may be used as a candidate Lyapunov function to prove the isolated system stability properties and as a storage function to emphasize the passivity properties when the chemical reactor interacts with the surroundings.
Tarik Omer Ogurtani - One of the best experts on this subject based on the ideXlab platform.
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Variational formulation of irreversible thermodynamics of surfaces and interfaces with grain-boundary triple-junction singularities under the capillary and electromigration forces in anisotropic two-dimensional space
Physical Review B, 2006Co-Authors: Tarik Omer OgurtaniAbstract:A variational irreversible thermodynamic method for curved surfaces and interfaces in a two-dimensional (2D) continuum, having anisotropic specific surface Gibbs free energy, is developed by utilizing the more realistic monolayer model of Verschaffelt and Guggenheim for the description of interfaces and surfaces in connection with the global Entropy Production hypothesis. This approach considers not only the asymmetric disposition of the grain-boundary triple junction, but also its dynamical effects on the morphological evolution of surfaces. The governing Euler equation and the associated boundary conditions (the strong solution) are derived rigorously by the variational technique applied on the positive definite rate of global Internal Entropy Production; the results are in excellent accord with those deduced by the first-principles theory of irreversible thermodynamics of curved surfaces with triple junctions as formulated previously by the author, using the basic postulate of the local Internal Entropy Production in connection with the microfinite-element method in discrete 2D space. At the final stage, the whole problem is converted into a variational extremum problem in order to obtain the weak solution in a class of smooth functions (i.e., Hermite functions) having continuous derivatives ${C}_{\ensuremath{\infty}}(\ensuremath{-}\ensuremath{\infty},+\ensuremath{\infty})$ by transforming the displacement field into the particle-flux representation using the principle of conservation of particles, including the phase transition. As an application of the weak solution, which is converted into a compact matrix format in the normalized and scaled time and space domain, a set of computer simulation experiments is performed on symmetrically disposed bicrystal thin metallic films having fourfold anisotropic specific surface Gibbs free energy to demonstrate the breaching effects caused by grain-boundary grooving under the surface drift diffusion driven by the capillarity without electromigration forces.
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irreversible thermodynamics of triple junctions during the intergranular void motion under the electromigration forces
International Journal of Solids and Structures, 2005Co-Authors: Tarik Omer Ogurtani, Ersin Emre OrenAbstract:Abstract A rigorous reformulation of Internal Entropy Production and the rate of Entropy flow is developed for multi-component systems consisting of heterophases, interfaces and/or surfaces. The result is a well-posed moving boundary value problem describing the dynamics of curved interfaces and surfaces associated with voids and/or cracks that are intersected by grain boundaries. Extensive computer simulations are performed for void configuration evolution during intergranular motion. In particular we simulate evolution resulting from the action of capillary and electromigration forces in thin film metallic interconnects having a “bamboo” structure, characterized by grain boundaries aligned perpendicular to the free surface of the metallic film interconnects. Analysis of experimental data utilizing previously derived mean time to failure formulas gives consistent values for interface diffusion coefficients and enthalpies of voids. 3.0 × 10 −6 exp(−0.62 eV/ kT ) m 2 s −1 is the value obtained for voids that form in the interior of the aluminum interconnects without surface contamination. 6.5 × 10 −6 exp(−0.84 eV/ kT ) m 2 s −1 is obtained for those voids that nucleate either at triple junctions or at the grain boundary-technical surface intersections, where the chemical impurities may act as trap centers for hopping vacancies.
J P Garciasandoval - One of the best experts on this subject based on the ideXlab platform.
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stability analysis and passivity properties of a class of thermodynamic processes an Internal Entropy Production approach
Chemical Engineering Science, 2016Co-Authors: J P Garciasandoval, Nicolas Hudon, Denis Dochain, V GonzalezalvarezAbstract:Abstract In this contribution, stability and passivity properties of a class of thermodynamic processes are addressed from a thermodynamical point of view. These thermodynamic processes can be constituted by multiple spatially homogeneous dynamic subsystems modeled by ordinary differential equations. It is shown that the Internal Entropy Production may be used as a Lyapunov function candidate to prove the isolated system stability properties and as a storage function to assess the passivity properties when the system interacts with the surroundings. In addition, it is shown that the stability condition depends on a matrix whose dimension is equal to the number of modeled dynamical phenomena taking place within the system, i.e. the number of phenomena can be smaller than the system dimension. Moreover, a port-controlled Hamiltonian representation of this class of systems based on the Internal Entropy Production is developed. Finally, the theory proposed is applied to three study cases: a heat exchanger, a ideal gas adiabatic chemical reactor and a ideal gas jacketed chemical reactor.
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stability analysis and passivity properties for a class of chemical reactors Internal Entropy Production approach
Computers & Chemical Engineering, 2015Co-Authors: J P Garciasandoval, V Gonzalezalvarez, C. CalderónAbstract:In this contribution, the stability and passivity properties of a class of chemical reactors are addressed from a thermodynamical point of view. For this purpose, a thermodynamical consistent model is derived from a generic gas reactor model whose rate is based on the reaction progress at the mesoscopic scale. It is shown that the Internal Entropy Production may be used as a candidate Lyapunov function to prove the isolated system stability properties and as a storage function to emphasize the passivity properties when the chemical reactor interacts with the surroundings.
C. Calderón - One of the best experts on this subject based on the ideXlab platform.
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stability analysis and passivity properties for a class of chemical reactors Internal Entropy Production approach
Computers & Chemical Engineering, 2015Co-Authors: J P Garciasandoval, V Gonzalezalvarez, C. CalderónAbstract:In this contribution, the stability and passivity properties of a class of chemical reactors are addressed from a thermodynamical point of view. For this purpose, a thermodynamical consistent model is derived from a generic gas reactor model whose rate is based on the reaction progress at the mesoscopic scale. It is shown that the Internal Entropy Production may be used as a candidate Lyapunov function to prove the isolated system stability properties and as a storage function to emphasize the passivity properties when the chemical reactor interacts with the surroundings.
Ersin Emre Oren - One of the best experts on this subject based on the ideXlab platform.
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irreversible thermodynamics of triple junctions during the intergranular void motion under the electromigration forces
International Journal of Solids and Structures, 2005Co-Authors: Tarik Omer Ogurtani, Ersin Emre OrenAbstract:Abstract A rigorous reformulation of Internal Entropy Production and the rate of Entropy flow is developed for multi-component systems consisting of heterophases, interfaces and/or surfaces. The result is a well-posed moving boundary value problem describing the dynamics of curved interfaces and surfaces associated with voids and/or cracks that are intersected by grain boundaries. Extensive computer simulations are performed for void configuration evolution during intergranular motion. In particular we simulate evolution resulting from the action of capillary and electromigration forces in thin film metallic interconnects having a “bamboo” structure, characterized by grain boundaries aligned perpendicular to the free surface of the metallic film interconnects. Analysis of experimental data utilizing previously derived mean time to failure formulas gives consistent values for interface diffusion coefficients and enthalpies of voids. 3.0 × 10 −6 exp(−0.62 eV/ kT ) m 2 s −1 is the value obtained for voids that form in the interior of the aluminum interconnects without surface contamination. 6.5 × 10 −6 exp(−0.84 eV/ kT ) m 2 s −1 is obtained for those voids that nucleate either at triple junctions or at the grain boundary-technical surface intersections, where the chemical impurities may act as trap centers for hopping vacancies.