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Irreversible Thermodynamics
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
A system is said to be in thermodynamic equilibrium when there are no noticeable changes macroscopically and the system is isolated from its surroundings. One of the primary requirements for equilibrium is the uniform temperature throughout the system or each part of the system in thermal contact. If this condition is not met, heat transfer takes place spontaneously from one location to another when the system is isolated. Another requirement is the absence of unbalanced forces between parts of the system. The system will be in thermal and mechanical equilibrium if the above two conditions are met, but it does not ensure the complete equilibrium. A process occurs involving a chemical reaction, a transfer of mass between phases, or both. Equilibrium thermodynamics is the study of transformations of matter and energy in systems with the theory based on thermodynamic equilibrium. Equilibrium is a state of balance in which potentials or driving forces within a system are in exact balance. Non-equilibrium thermodynamics, on the other hand, deals with the physical systems that are not in thermodynamic equilibrium. Non-equilibrium thermodynamics can be effectively used to describe the biological processes that involve protein folding/unfolding and transport through the membranes.
An Introduction to the Thermodynamics Calculation of PHA Production in Microbes
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Chaozhi Pan, Liya Ge, Po-Heng (Henry) Lee, Giin-Yu Amy Tan
Thermodynamics is categorized into equilibrium thermodynamics and non-equilibrium thermodynamics. Enthalpy (heat adsorbed under constant pressure) and entropy (the degree of order in a system) are also two key concepts of thermodynamics. Classic thermodynamics emphasizes equilibrium in a closed system, while a biological system is an open and dynamic system, which converts high-enthalpy and low-entropy substrates into low-enthalpy and high-entropy metabolites [21]. Since non-equilibrium thermodynamics also is concerned with the mass flow, it is beyond the scope of this chapter and will not be discussed here. In a standard reaction, the Gibbs energy change (ΔGr0) of a chemical reaction describes the effects of enthalpy (ΔHr0) and entropy (ΔS0) changes: ΔGR0=ΔHR0−TΔS0
Computational prediction of the long-term behavior of the femoral density after THR using the Silent Hip stem
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Zainab Al-Hajaj, Pouria Tavakkoli Avval, Habiba Bougherara
The theory behind the model used in our study is phenomenological as it was built on linear non-equilibrium thermodynamics. It does not relate directly to the mechanotransduction that occurs within cells. It was assumed that the rate of the trace of strains controls bone cells behavior as was suggested by the theory (Klika 2010), nevertheless, other mechanical stimuli including fluid flow, transport of nutrients, and other factors could also influence the process. Additionally, kinetics that control mechanisms in bone remodeling such as the RANKL-RANK-OPG chain were neglected in this study (Klika et al. 2014), in which it could have a more detailed estimation of the biological control mechanism of the bone remodeling behavior but, at the same time, introduces additional degrees of freedom and complexity into the model. Furthermore, in the performed study with the proposed computational model, the analysis was not based on real time duration. Yet, the convergence of the iterative procedure was only considered when the density of the elements stopped indicating a significant change. It can be explained from the clinical perspective, it is a long-term response when the femoral density gets to a stable condition (albeit being a dynamical equilibrium). In addition, in the current study, the anisotropic behavior of the bone was ignored as each element was considered to be an isotropic material.
Non-equilibrium thermodynamics approach for the coupled heat and mass transfer of wet mineral porous media in dielectric and magnetic drying
Published in Drying Technology, 2020
B. A. Fu, M. Q. Chen, Q. H. Li
According to the non-equilibrium thermodynamics, the entropy source strength for the magnetic hematite thin layer in an electromagnetic field is given as[16]: where J′q is the heat flux, W m−2; Jk is the mass flux, mol m−2; χ is the electric susceptibility of the material; μr is the permeability; Beq is the magnetic induction density at the equilibrium state, T; M is the magnetization, A m−1; zk is the polarized charge density, C m−3, which can be neglected due to the bond strengths between the water molecules and the materials[17]; and μk is the chemical potential, J mol−1, which can be estimated as: where μl and μg are the chemical potential of liquid water and water vapor, respectively, J mol−1.
Logical and information aspects in surface science: friction, capillarity, and superhydrophobicity
Published in International Journal of Parallel, Emergent and Distributed Systems, 2018
Besides the growth of tribofilms, there is another frictional evolutionary process. When frictional sliding starts, at first the coefficient of friction usually higher than in the steady state regime. The initial non-stationary regime is usually called run-in [1]. During this regime the surfaces tend to adjust to each other, for example, by changing roughness parameters due to an extensive deformation and fracture of asperities. A number of attempts have been made in the literature to relate this effect to the ‘minimum entropy production principle’ of non-equilibrium thermodynamics. According to this principle, a dynamical system tunes itself up to the regime with minimum energy dissipation, corresponding to the minimum of (supplied by ). For a frictional system, this is a regime with lowest coefficient of friction.