The Experts below are selected from a list of 49383 Experts worldwide ranked by ideXlab platform
Michael M. Khonsari - One of the best experts on this subject based on the ideXlab platform.
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On the role of damage energy in the fatigue degradation characterization of a composite laminate
Composites Part B: Engineering, 2013Co-Authors: M. Naderi, Michael M. KhonsariAbstract:Abstract The results of a series of experiments to characterize the damage behavior of a glass/epoxy laminate are presented in terms of hysteresis energy dissipation, damage energy variation, energy associated with thermal capacity, temperature rise, and a new method that utilizes Thermodynamic Entropy production. Results are presented for the observed damage stages and their durations. Different life spans for damage stages are observed based on the plots of damage energy and hysteresis energy. A theoretical model based on the energy balance and the second law of Thermodynamics is presented that takes into account the role of hysteresis, damage energy and energy associated with thermal capacity as well as the Thermodynamic Entropy in the fatigue degradation of a composite laminate. The results of Thermodynamic Entropy indicate that interpretation of degradation within the laminate requires consideration of both the damage energy and hysteresis energy.
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real time fatigue life monitoring based on Thermodynamic Entropy
Structural Health Monitoring-an International Journal, 2011Co-Authors: M. Naderi, Michael M. KhonsariAbstract:This article presents a methodology for real-time monitoring of fatigue life in machinery components that utilizes the accumulation of Entropy to assess the severity of degradation associated with ...
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An experimental approach to low-cycle fatigue damage based on Thermodynamic Entropy
International Journal of Solids and Structures, 2010Co-Authors: M. Naderi, Michael M. KhonsariAbstract:This paper presents an experimental approach to fatigue damage in metals based on Thermodynamic theory of irreversible process. Fatigue damage is an irreversible progression of cyclic plastic strain energy that reaches its critical value at the onset of fracture. In this work, irreversible cyclic plastic energy in terms of Entropy generation is utilized to experimentally determine the degradation of different specimens subjected to low cyclic bending, tension-compression, and torsional fatigue. Experimental results show that the cyclic energy dissipation in the form of Thermodynamic Entropy can be effectively utilized to determine the fatigue damage evolution. An experimental relation between Entropy generation and damage variable is developed.
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On the Thermodynamic Entropy of fatigue fracture
Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, 2009Co-Authors: M. Naderi, M. Amiri, Michael M. KhonsariAbstract:Entropy production during the fatigue process can serve as a measure of degradation. We postulate that the Thermodynamic Entropy of metals undergoing repeated cyclic load reaching the point of fracture is a constant, independent of geometry, load and frequency. That is, the necessary and sufficient condition for the final fracture of a metal undergoing fatigue load corresponds to a constant irreversible Entropy gain. To examine validity, we present the results of an extensive set of both experimental tests and analytical predictions that involve bending, torsion and tension-compression of aluminium 6061-T6 and stainless steel 304 specimens. The concept of tallying up the Entropy generation has application in determining the fatigue life of components undergoing cyclic bending, torsion and tension-compression.
M. Naderi - One of the best experts on this subject based on the ideXlab platform.
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On the role of damage energy in the fatigue degradation characterization of a composite laminate
Composites Part B: Engineering, 2013Co-Authors: M. Naderi, Michael M. KhonsariAbstract:Abstract The results of a series of experiments to characterize the damage behavior of a glass/epoxy laminate are presented in terms of hysteresis energy dissipation, damage energy variation, energy associated with thermal capacity, temperature rise, and a new method that utilizes Thermodynamic Entropy production. Results are presented for the observed damage stages and their durations. Different life spans for damage stages are observed based on the plots of damage energy and hysteresis energy. A theoretical model based on the energy balance and the second law of Thermodynamics is presented that takes into account the role of hysteresis, damage energy and energy associated with thermal capacity as well as the Thermodynamic Entropy in the fatigue degradation of a composite laminate. The results of Thermodynamic Entropy indicate that interpretation of degradation within the laminate requires consideration of both the damage energy and hysteresis energy.
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real time fatigue life monitoring based on Thermodynamic Entropy
Structural Health Monitoring-an International Journal, 2011Co-Authors: M. Naderi, Michael M. KhonsariAbstract:This article presents a methodology for real-time monitoring of fatigue life in machinery components that utilizes the accumulation of Entropy to assess the severity of degradation associated with ...
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An experimental approach to low-cycle fatigue damage based on Thermodynamic Entropy
International Journal of Solids and Structures, 2010Co-Authors: M. Naderi, Michael M. KhonsariAbstract:This paper presents an experimental approach to fatigue damage in metals based on Thermodynamic theory of irreversible process. Fatigue damage is an irreversible progression of cyclic plastic strain energy that reaches its critical value at the onset of fracture. In this work, irreversible cyclic plastic energy in terms of Entropy generation is utilized to experimentally determine the degradation of different specimens subjected to low cyclic bending, tension-compression, and torsional fatigue. Experimental results show that the cyclic energy dissipation in the form of Thermodynamic Entropy can be effectively utilized to determine the fatigue damage evolution. An experimental relation between Entropy generation and damage variable is developed.
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On the Thermodynamic Entropy of fatigue fracture
Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, 2009Co-Authors: M. Naderi, M. Amiri, Michael M. KhonsariAbstract:Entropy production during the fatigue process can serve as a measure of degradation. We postulate that the Thermodynamic Entropy of metals undergoing repeated cyclic load reaching the point of fracture is a constant, independent of geometry, load and frequency. That is, the necessary and sufficient condition for the final fracture of a metal undergoing fatigue load corresponds to a constant irreversible Entropy gain. To examine validity, we present the results of an extensive set of both experimental tests and analytical predictions that involve bending, torsion and tension-compression of aluminium 6061-T6 and stainless steel 304 specimens. The concept of tallying up the Entropy generation has application in determining the fatigue life of components undergoing cyclic bending, torsion and tension-compression.
Shin-ichi Sasa - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic Entropy as a Noether invariant in a Langevin equation
Journal of Statistical Mechanics: Theory and Experiment, 2020Co-Authors: Yuki Minami, Shin-ichi SasaAbstract:We study the Thermodynamic Entropy as a Noether invariant in a stochastic process. Following the Onsager theory, we consider the Langevin equation for a Thermodynamic variable in a thermally isolated system. By analyzing the Martin-Siggia-Rose-Janssen-de Dominicis action of the Langevin equation, we find that this action possesses a continuous symmetry in quasi-static processes, which leads to the Thermodynamic Entropy as the Noether invariant for the symmetry.
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Thermodynamic Entropy as a Noether invariant
Physical review letters, 2016Co-Authors: Shin-ichi Sasa, Yuki YokokuraAbstract:We study a classical many-particle system with an external control represented by a time-dependent extensive parameter in a Lagrangian. We show that Thermodynamic Entropy of the system is uniquely characterized as the Noether invariant associated with a symmetry for an infinitesimal nonuniform time translation t→t+ηℏβ, where η is a small parameter, ℏ is the Planck constant, β is the inverse temperature that depends on the energy and control parameter, and trajectories in the phase space are restricted to those consistent with quasistatic processes in Thermodynamics.
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Possible extended forms of Thermodynamic Entropy
Journal of Statistical Mechanics: Theory and Experiment, 2014Co-Authors: Shin-ichi SasaAbstract:Thermodynamic Entropy is determined by a heat measurement through the Clausius equality. The Entropy then formalizes a fundamental limitation of operations by the second law of Thermodynamics. The Entropy is also expressed as the Shannon Entropy of the microscopic degrees of freedom. Whenever an extension of Thermodynamic Entropy is attempted, we must pay special attention to how its three different aspects just mentioned are altered. In this paper, we discuss possible extensions of the Thermodynamic Entropy.
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Thermodynamic Entropy and Excess Information Loss in Dynamical Systems with Time-Dependent Hamiltonians
Physical Review Letters, 1999Co-Authors: Shin-ichi Sasa, Teruhisa KomatsuAbstract:We study a dynamical system with time dependent Hamiltonian by numerical experiments so as to find a relation between Thermodynamics and chaotic nature of the system. Excess information loss, defined newly based on Lyapunov analysis, is related to the increment of Thermodynamic Entropy. Our numerical results suggest that the positivity of Entropy increment is expressed by the principle of the minimum excess information loss.
Axel Kleidon - One of the best experts on this subject based on the ideXlab platform.
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Quantifying the Thermodynamic Entropy budget of the land surface: is this useful?
Earth System Dynamics, 2011Co-Authors: Nathaniel A. Brunsell, Stanislaus J. Schymanski, Axel KleidonAbstract:Abstract. As a system is moved away from a state of Thermodynamic equilibrium, spatial and temporal heterogeneity is induced. A possible methodology to assess these impacts is to examine the Thermodynamic Entropy budget and assess the role of Entropy production and transfer between the surface and the atmosphere. Here, we adopted this Thermodynamic framework to examine the implications of changing vegetation fractional cover on land surface energy exchange processes using the NOAH land surface model and eddy covariance observations. Simulations that varied the relative fraction of vegetation were used to calculate the resultant Entropy budget as a function of fraction of vegetation. Results showed that increasing vegetation fraction increases Entropy production by the land surface while decreasing the overall Entropy budget (the rate of change in Entropy at the surface). This is accomplished largely via simultaneous increase in the Entropy production associated with the absorption of solar radiation and a decline in the Bowen ratio (ratio of sensible to latent heat flux), which leads to increasing the Entropy export associated with the latent heat flux during the daylight hours and dominated by Entropy transfer associated with sensible heat and soil heat fluxes during the nighttime hours. Eddy covariance observations also show that the Entropy production has a consistent sensitivity to land cover, while the overall Entropy budget appears most related to the net radiation at the surface, however with a large variance. This implies that quantifying the Thermodynamic Entropy budget and Entropy production is a useful metric for assessing biosphere-atmosphere-hydrosphere system interactions.
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Quantifying the Thermodynamic Entropy budget of the land surface: is this useful?
2011Co-Authors: Nathaniel A. Brunsell, Stanislaus J. Schymanski, Axel KleidonAbstract:Abstract. As a system is moved away from a state of Thermodynamic equilibrium, spatial and temporal heterogeneity is induced. A possible methodology to assess these impacts is to examine the Thermodynamic Entropy budget and assess the role of Entropy production and transfer between the surface and the atmosphere. Here, we adopted this Thermodynamic framework to examine the implications of changing vegetation fractional cover on land surface energy exchange processes using the NOAH land surface model and eddy covariance observations. Simulations that varied the relative fraction of vegetation were used to calculate the resultant Entropy budget as a function of fraction of vegetation. Results showed that increasing vegetation fraction increases Entropy production by the land surface while decreasing the overall Entropy budget (the rate of change in Entropy at the surface). This is accomplished largely via simultaneous increase in the Entropy production associated with the absorption of solar radiation and a decline in the Bowen ratio (ratio of sensible to latent heat flux), which leads to increasing the Entropy export associated with the latent heat flux during the daylight hours and dominated by Entropy transfer associated with sensible heat and soil heat fluxes during the nighttime hours. Eddy covariance observations also show that the Entropy production has a consistent sensitivity to land cover, while the overall Entropy budget appears most related to the net radiation at the surface. This implies that quantifying the Thermodynamic Entropy budget and Entropy production is a useful metric for assessing biosphere-atmosphere-hydrosphere system interactions.
Nathaniel A. Brunsell - One of the best experts on this subject based on the ideXlab platform.
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Quantifying the Thermodynamic Entropy budget of the land surface: is this useful?
Earth System Dynamics, 2011Co-Authors: Nathaniel A. Brunsell, Stanislaus J. Schymanski, Axel KleidonAbstract:Abstract. As a system is moved away from a state of Thermodynamic equilibrium, spatial and temporal heterogeneity is induced. A possible methodology to assess these impacts is to examine the Thermodynamic Entropy budget and assess the role of Entropy production and transfer between the surface and the atmosphere. Here, we adopted this Thermodynamic framework to examine the implications of changing vegetation fractional cover on land surface energy exchange processes using the NOAH land surface model and eddy covariance observations. Simulations that varied the relative fraction of vegetation were used to calculate the resultant Entropy budget as a function of fraction of vegetation. Results showed that increasing vegetation fraction increases Entropy production by the land surface while decreasing the overall Entropy budget (the rate of change in Entropy at the surface). This is accomplished largely via simultaneous increase in the Entropy production associated with the absorption of solar radiation and a decline in the Bowen ratio (ratio of sensible to latent heat flux), which leads to increasing the Entropy export associated with the latent heat flux during the daylight hours and dominated by Entropy transfer associated with sensible heat and soil heat fluxes during the nighttime hours. Eddy covariance observations also show that the Entropy production has a consistent sensitivity to land cover, while the overall Entropy budget appears most related to the net radiation at the surface, however with a large variance. This implies that quantifying the Thermodynamic Entropy budget and Entropy production is a useful metric for assessing biosphere-atmosphere-hydrosphere system interactions.
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Quantifying the Thermodynamic Entropy budget of the land surface: is this useful?
2011Co-Authors: Nathaniel A. Brunsell, Stanislaus J. Schymanski, Axel KleidonAbstract:Abstract. As a system is moved away from a state of Thermodynamic equilibrium, spatial and temporal heterogeneity is induced. A possible methodology to assess these impacts is to examine the Thermodynamic Entropy budget and assess the role of Entropy production and transfer between the surface and the atmosphere. Here, we adopted this Thermodynamic framework to examine the implications of changing vegetation fractional cover on land surface energy exchange processes using the NOAH land surface model and eddy covariance observations. Simulations that varied the relative fraction of vegetation were used to calculate the resultant Entropy budget as a function of fraction of vegetation. Results showed that increasing vegetation fraction increases Entropy production by the land surface while decreasing the overall Entropy budget (the rate of change in Entropy at the surface). This is accomplished largely via simultaneous increase in the Entropy production associated with the absorption of solar radiation and a decline in the Bowen ratio (ratio of sensible to latent heat flux), which leads to increasing the Entropy export associated with the latent heat flux during the daylight hours and dominated by Entropy transfer associated with sensible heat and soil heat fluxes during the nighttime hours. Eddy covariance observations also show that the Entropy production has a consistent sensitivity to land cover, while the overall Entropy budget appears most related to the net radiation at the surface. This implies that quantifying the Thermodynamic Entropy budget and Entropy production is a useful metric for assessing biosphere-atmosphere-hydrosphere system interactions.
