Dissipation effects in mechanics and thermodynamics

Güémez, J.; Fiolhais, M.

doi:10.1088/0143-0807/37/4/045101

Cited by 9 publications

(9 citation statements)

References 27 publications

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“…This is similar to situations involving a component of pseudowork-energy balance in dissipative systems [73][74][75][76][77][78][79].…”

Section: A Mechanical Energymentioning

confidence: 68%

Physical pendulum model: Fractional differential equation and memory effects

Gonçalves,

Fernandes,

Ferraz

et al. 2020

Preprint

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A detailed analysis of three pendular motion models is presented. Inertial effects, self-oscillation, and memory, together with non-constant moment of inertia, hysteresis and negative damping are shown to be required for the comprehensive description of the free pendulum oscillatory regime. The effects of very high initial amplitudes, friction in the roller bearing axle, drag, and pendulum geometry are also analysed and discussed. The model that consists of a fractional differential equation provides both the best explanation of, and the best fits to, experimental high resolution and long-time data gathered from standard action-camera videos.

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“…This is similar to situations involving a component of pseudowork-energy balance in dissipative systems [73][74][75][76][77][78][79].…”

Section: A Mechanical Energymentioning

confidence: 68%

Physical pendulum model: Fractional differential equation and memory effects

Gonçalves,

Fernandes,

Ferraz

et al. 2020

Preprint

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“…Thermodynamic state index can also be used to model degradation evolution in the spring in the system without any empirical test data. Examples of this are given in references [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In Newtonian mechanics, degradation evolution must be introduced by an empirical curve fit.…”

Section: Discussionmentioning

confidence: 99%

“…If irreversible processes are to be included in the Lagrangian, the second law of thermodynamics must be considered [3]. In Newtonian mechanics, the effect of dissipative forces is included as impulsive forces and pseudo-forces [4]. Hence, the Newtonian mechanics deals with space-time coordinates and does not consider a change in entropy of the system.…”

Section: Derivation Of the Dynamic Equilibrium Equationmentioning

confidence: 99%

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Dynamic Equilibrium Equations in Unified Mechanics Theory

Lee

Rao

et al. 2021

Applied Mechanics

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Traditionally dynamic analysis is done using Newton’s universal laws of the equation of motion. According to the laws of Newtonian mechanics, the x, y, z, space-time coordinate system does not include a term for energy loss, an empirical damping term “C” is used in the dynamic equilibrium equation. Energy loss in any system is governed by the laws of thermodynamics. Unified Mechanics Theory (UMT) unifies the universal laws of motion of Newton and the laws of thermodynamics at ab-initio level. As a result, the energy loss [entropy generation] is automatically included in the laws of the Unified Mechanics Theory (UMT). Using unified mechanics theory, the dynamic equilibrium equation is derived and presented. One-dimensional free vibration analysis with frictional dissipation is used to compare the results of the proposed model with that of a Newtonian mechanics equation. For the proposed entropy generation equation in the system, the trend of predictions is comparable with the reported experimental results and Newtonian mechanics-based predictions.

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“…However, in the presence of dissipative forces, the mechanical energy of the system is not conserved and the system evolves according to the principle of minimum potential energy [2]: the endpoint of the trajectory has to be a state of minimum potential energy. In these cases it might be necessary to take into account thermal effects, by using the first law of thermodynamics [3]. The mechanical energy dissipated as heat it taken into account by the first law, and the time evolution of the system follows the principle of maximum entropy: the entropy of the universe increases until it reaches a maximum compatible with the actual conditions of the process (second law of thermodynamics).…”

Section: Introductionmentioning

confidence: 99%

Principles of time evolution in classical physics

Güémez

Fiolhais

2018

Eur. J. Phys.

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We address principles of time evolution in classical mechanical/thermodynamical systems in translational and rotational motion, in three cases: when there is conservation of mechanical energy, when there is energy dissipation and when there is mechanical energy production. In the first case, the time derivative of the Hamiltonian vanishes. In the second one, when dissipative forces are present, the time evolution is governed by the minimum potential energy principle, or, equivalently, maximum increase of the entropy of the universe. Finally, in the third situation, when internal sources of work are available to the system, it evolves in time according to the principle of minimum Gibbs function. We apply the Lagrangian formulation to the systems, dealing with the non-conservative forces using restriction functions such as the Rayleigh dissipative function.

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Dissipation effects in mechanics and thermodynamics

Cited by 9 publications

References 27 publications

Physical pendulum model: Fractional differential equation and memory effects

Physical pendulum model: Fractional differential equation and memory effects

Dynamic Equilibrium Equations in Unified Mechanics Theory

Principles of time evolution in classical physics

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