I demonstrate that, under certain circumstances, regions of negative energy density can undergo gravitational collapse into a black hole. The resultant exterior black hole spacetimes necessarily have negative mass and non-trivial topology. A full theory of quantum gravity, in which topology-changing processes take place, could give rise to such spacetimes. 2 Internet: [email protected] T...

I demonstrate that, under certain circumstances, regions of negative energy density can undergo gravitational collapse into a black hole. The resultant exterior black hole spacetimes necessarily have negative mass and non-trivial topology. A full theory of quantum gravity, in which topologychanging processes take place, could give rise to such spacetimes. 2 Internet: [email protected] Th...

We investigate the thermodynamical properties of black holes in (3+1) and (2+1) dimensional Einstein gravity with a negative cosmological constant. In each case, the thermodynamic internal energy is computed for a finite spatial region that contains the black hole. The temperature at the boundary of this region is defined by differentiating the energy with respect to entropy, and is equal to th...

Abstract: In this study, the effect of fuel injection discharge curve and injection pressure simultaneously for upgrading power of heavy duty diesel engine by simulation of combustion process in AVL-Fire software are discussed. Hence, the fuel injection discharge curve was changed from semi-triangular to rectangular which is usual in common rail fuel injection system. Injection pressure with r...

We show that the order of energies of negative (X ) and positive (Xþ) trions in quantum wires is determined by the relative electron and hole lateral confinements. For equal electron and hole confinement, Xþ has a larger binding energy, but a small imbalance towards a stronger hole localization changes the order of the X and Xþ recombination lines in the photoluminescence spectrum.

We discuss black hole energy processes that could serve as the mechanism for relativistic jets. The energy-extraction process of Roger Penrose is presented. The existence of the negative energy region is derived from the extreme Kerr metric. Theoretical limits on the efficiency of the process are discussed. An analogous process for a Kerr-Newman hole is presented. The Blandford-Znajek process i...

We have found an exact solution of spherically symmetrical Einstein equations describing a black hole with a special type phantom energy source. It is surprising to note that our solution is analogous to Reissner-Nordström black hole. Recent astrophysical observations have confirmed that the Universe at present is expanding with an acceleration. It is proposed that this unexpected cosmological ...

water conveyance through pumping takes a lot of energy and cost and therefore, its application should be accompanied by exact design of pumping station as well as correct positions of pumps and their subsidiary apparatus. sumps are designed for many pumping stations and often face the problems of vortex and irregular flows. therefore an investigation of the general flow pattern in sumps in diff...

When a black hole evaporates, there arises a net energy flow from the black hole into its outside environment due to the Hawking radiation and the energy accretion onto black hole. Exactly speaking, any thermal equilibrium state has no energy flow, and therefore the black hole evaporation is a nonequilibrium process. To study details of evaporation process, nonequilibrium effects of the net ene...