We construct in the supergravity framework a relation between thermal chargeless nonextremal black three-branes and thermal Dirichlet branes-antibranes systems. We propose this relation as a possible explanation for the intriguing similarity between the black branes BekensteinHawking entropy and the field theory entropy of thermal branes-antibranes. We comment on various relations between brane...

Natural convection in an inclined rectangular cavity filled with air is numerically investigated. The cavity is heated and cooled along the active walls whereas the two other walls of the cavity are adiabatic. Entropy generation due to heat transfer and fluid friction has been determined in transient state for laminar natural convection by solving numerically: the continuity, momentum and energ...

We propose a system for measuring entropy 1 variations, S, in thermal systems using pyroelectric sensors. 2 These sensors convert time-dependent temperature variations 3 into electrical current. Consequently, heat and temperature 4 variations are obtained, and sensor entropy is inferred. Various 5 polyvinylidene fluoride and lead zirconate titanate sensors have 6 been tested. Two types of measu...

The frequent misunderstanding of information entropy is pointed out. It is shown that, contrary to fortuitous situations and common beliefs, there is no general interrelation between the information entropy and the thermodynamical entropy. We point out that the change of information entropy during measurement is determined by the resolution of the measurement instrument and these changes do not...

In this study, convection flow in microchannel heat sink with offset fan-shaped reentrant cavities in sidewall filled with Fe3O4-water is numerically investigated. The effects of changing some parameters such as Reynolds number and magnetic field are considered. The nanofluid flow is laminar, steady and incompressible, while the thermo-physical properties of nanoparticles were assumed constant....

We develop the argument that the Gibbs-von Neumann entropy is the appropriate statistical mechanical generalisation of the thermodynamic entropy, for macroscopic and microscopic systems , whether in thermal equilibrium or not, as a consequence of Hamiltonian dynamics. The mathematical treatment utilises well known results [Gib02, Tol38, Weh78, Par89], but most importantly, incorporates a variet...

This study numerically investigated heat transfer and fluid flow characteristics in a novel cylindrical heat sink with helical minichannels for the laminar flow of fluid with temperature-dependent properties. A finite volume method was employed to obtain the solution of governing equations. The effects of helical angle, channel aspect ratio, and Reynolds number, which were regarded as main para...

The effect of gravity upon changes of the entropy of a gravity-dominated system is discussed. In a universe dominated by vacuum energy, gravity is repulsive, and there is accelerated expansion. Furthermore, inhomogeneities are inflated and the universe approaches a state of thermal equilibrium. The difference between the evolution of the cosmic entropy in a co-moving volume in an inflationary e...

the aim of this study is to find the optimal water pressure and percentage of supply vapour in the feed water heaters (fwhs) of steam power plants, such that they maximize the thermal efficiency of the rankine cycle within pre-specified values of minimum and maximum pressures of the thermodynamic cycle. thermal efficiency is defined as a function of unknown variables (fluid pressure and vapour ...