The Second Law of Thermodynamics in a Quantum Heat Engine Model

The second law of thermodynamics has been proven by many facts in classical world. Is there any new property of it in quantum world？ In this paper, we calculate the change of entropy in T.D. Kieu＇s model for quantum heat engine （QHE） and prove the broad validity of the second law of thermodynamics. It is shown that the entropy of the quantum heat engine neither decreases in a whole cycle, nor decreases in either stage of the cycle. The second law of thermodynamics still holds in this QHE model. Moreover, although the modified quantum heat engine is capable of extracting more work, its efficiency does not improve at all. It is neither beyond the efficiency of T.D. Kieu＇s initial model,nor greater than the reversible Carnot efficiency.

The Generalized Thermodynamic Temperature and the New Expressions of the First and the Second Law of Thermodynamics

The classical thermodynamics reflects the significant relationship between the heat and the temperature. On the basis of the relationships, according to the mathematical derivation, this paper structures the conceptions of generalized heat, generalized thermodynamic temperature, generalized entropy and so on. The series of conceptions in the classical thermodynamics is merely a special case of the generalized thermodynamics. Based on these conceptions of generalized thermodynamics, this paper presents the new expressions of the first law and the second law of thermodynamics. In other words, these expressions are endued with new explanations. The Eq. LZ = kTS given by this paper provides theoretical basis for these new expressions.

Effects of the porous medium and water-silver biological nanofluid on the performance of a newly designed heat sink by using first and second laws of thermodynamics

The aim of this numerical investigation is to evaluate the laminar forced convection of biologically synthesized water-silver nanofluid through a heat sink(HS)filled with porous foam(PHS)using first and second laws of thermodynamics.The impacts of inlet velocity(V=0.5–3 m·s^-1)and volume fraction of nanofluid(φ=0–1%)on the performance metrics of HS are assessed and the outcomes are compared with those of the non-porous HS(NHS).The outcomes revealed that for both the PHS and NHS,the increase of V causes an intensification in convection coefficient,pumping power,and entropy generation due to fluid friction,while the maximum CPU temperature,thermal resistance,and entropy generation due to the heat transfer reduces by boosting V.Also,it was found that the augmentation of V results in intensification in convection coefficient,pumping power,overall hydrothermal performance,and frictional entropy generation,while the opposite is true for maximum CPU temperature,thermal resistance,and thermal entropy generation.Furthermore,it was reported that,except forφ=0.5%,the overall hydrothermal performance of NHS is better than that of PHS,while PHS has better second-law performance than NHS in all the studied cases.Also,it can be concluded that the best hydrothermal performance for PHS belongs toφ=1%and V=0.5 m·s^-1,while for NHS,these values are 1%and 2 m·s^-1.

Applications of a Single Molecule Theory of Protein Dynamics

A single molecule theory for protein dynamics has been developed since 2012. It consists of the concepts of conformational Gibbs free energy function (CGF) and single molecule thermodynamic hypothesis (STH) that claims that all stable conformations are (local or global) minimizers of CGF. These are enough to give a unified explanations and mechanisms to many aspects of protein dynamics such as protein folding;allostery;denaturation;and intrinsically disordered proteins. Formulas of CGF in water environment had been derived via quantum statistics. Applications of them to soluble proteins are: docking Gibbs free energy difference formula and a practical way to search better docking site;single molecule binding affinity;predicting and explaining why structures of a monomeric globular protein looks like a globule and is tightly packed with a hydrophobic core;a representation of the hydrophobic effect;and a wholistic view to structures of water soluble proteins.

IMPROVEMENT OF A GLOBAL SPECTRAL MODEL BY INTRODUCING THE SECONDLAW OF THERMODYNAMICS

The second law of thermodynamics has never been taken into account in the traditional hydrodynamics and numer- ical weather prediction models,which is a serious oversight in the history of mechanics.Introducing the thermodynamic irreversibility into the hydrodynamic systems,the theory and method proposed in this study would not only lead the outputs of a numerical weather prediction model to noticeable improvement,but lead the structure of hydrodynamics to deepgoing transformation.

THE UNIFIED ELASTIC-VISCOSIC-PLASTIC THEORY OF SOLIDS

In this paper, mt unified elastic-viscosic-plastic theory which can compute the change of elastic, viscosic and plastic state of each point in the body is proposed. The theory is based on the laws of thermodynamics and the pseudo elastic postulate. lit the paper, the constitutive equations and variational principles are deduced. From which, the finite element method of both space and time may be easily formulated. Note that, by choosing the material parameters properly, the plastic constitutive equations currently used may be given.

Entropies of the various components of the universe

In this study, we investigate the entropies of photons, ideal gas-like dust(baryonic matter), and a special kind of dark energy in the context of cosmology. When these components expand freely with the universe, we calculate the entropy and specific entropy of each component from the perspective of statistics. Under specific assumptions and conditions, the entropies of these components can satisfy the second law of thermodynamics independently. Our calculations show that the specific entropy of matter cannot be a constant during the expansion of the universe, except for photons. When these components interact with the space-time background, particle production(annihilation) can occur. We study the influence of the interaction on the entropies of these components and obtain the conditions guaranteeing that the entropy of each component satisfies the second law of thermodynamics.