The null-brane background is a simple smooth 1/2 BPS solution of string theory. By tuning a parameter, this background develops a big crunch/big bang type singularity. We construct the DLCQ description of this space-time in terms of a Yang-Mills theory on a time-dependent space-time. Our dual Matrix description provides a nonperturbative framework in which the fate of both (null) time, and the ...

We study the expansion of the universe at late times in the case that the cosmological constant obeys certain scaling laws motivated by renormalisation group running in quantum theories. The renormalisation scale is identified with the Hubble scale and the inverse radii of the event and particle horizon, respectively. We find de Sitter solutions, power-law expansion and super-exponential expans...

We study the renormalisation group running of the cosmological and the Newton constant, where the renormalisation scale is given by the inverse of the radius of the cosmological event horizon. In this framework, we discuss the future evolution of the universe, where we find stable de Sitter solutions, but also “big crunch”-like and “big rip”-like events, depending on the choice of the parameter...

We show that a class of 3+1 dimensional Friedmann-RobertsonWalker cosmologies can be embedded within a variety of solutions of string theory. In some realizations the apparent singularities associated with the big bang or big crunch are resolved at non-singular horizons of higher-dimensional quasi-black hole solutions (with compactified real time); in others plausibly they are resolved at D-bra...

Abstract This article is an exercise in elementary mechanics and thermodynamics. It emphasizes the basic difference between thermodynamics which lies irreversibility of latter theory. Clausius [1] (Poggendorff’s Annalen der Physik, p. 125, 1865) – discoverer entropy was led to express dichotomy famous slogan die Energie Welt ist constant, Entropie strebt einem Maximum zu. (Gibbs put these sloga...

Power system voltage security is improved by optimizing reactive power dispatch (ORPD). ORPD problem is a multi-constrained, multi-objective problem involving both continuous and discrete control variables. An efficient optimization technique is needed for handling such a challenging objective function. Generator bus voltages, transformer tap positions and shunt Var compensator settings are the...