The Price of WMAP Inflation in Supergravity

The three-year data from WMAP are in stunning agreement with the simplest possible quadratic potential for chaotic inflation, as well as with new or symmetry-breaking inflation. We investigate the possibilities for incorporating these potentials within supergravity, particularly of the no-scale type that is motivated by string theory. Models with inflation driven by the matter sector may be constructed in no-scale supergravity, if the moduli are assumed to be stabilised by some higher-scale dynamics and at the expense of some fine-tuning. We discuss specific scenarios for stabilising the moduli via either D- or F-terms in the effective potential, and survey possible inflationary models in the presence of D-term stabilisation.Comment: 15 pages, 6 figures, plain Late

Reheating Temperature and Gauge Mediation Models of Supersymmetry Breaking

For supersymmetric theories with gravitino dark matter, the maximal reheating temperature consistent with big bang nucleosynthesis bounds arises when the physical gaugino masses are degenerate. We consider the cases of a stau or sneutrino next-to-lightest superpartner, which have relatively less constraint from big bang nucleosynthesis. The resulting parameter space is consistent with leptogenesis requirements, and can be reached in generalized gauge mediation models. Such models illustrate a class of theories that overcome the well-known tension between big bang nucleosynthesis and leptogenesis.Comment: 30 pages, 4 figures; v2: refs adde

On low-energy predictions of unification models inspired by F-theory

The aim of this paper is to discuss phenomenological consequences of a particular unification model (Z_3 model) inspired by F-theory. The most distinctive feature of this model is a variety of (cosmologically feasible) options for the NLSP and NNLSP, beyond the usually considered benchmark scenarios.Comment: LaTeX, 11 pages, 12 figure

Curvature and isocurvature perturbations in two-field inflation

We study cosmological perturbations in two-field inflation, allowing for non-standard kinetic terms. We calculate analytically the spectra of curvature and isocurvature modes at Hubble crossing, up to first order in the slow-roll parameters. We also compute numerically the evolution of the curvature and isocurvature modes from well within the Hubble radius until the end of inflation. We show explicitly for a few examples, including the recently proposed model of ‘roulette’ inflation, how isocurvature perturbations affect significantly the curvature perturbation between Hubble crossing and the end of inflation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58173/2/jcap7_07_014.pd

Design and distribution of air nozzles in the biomass boiler assembly

Due to energy crisis as well as increasing pollution of the enviroment, renewable energy sources usage increases all over the world. These facts encouraged authors to start research over developing a uniform biomass boiler calculation model. Paper presents the design of biomass boiler assembly created for the organic Rankine cycle unit since these systems could achieve strong position in energy industry. To achieve optimal performance of boiler assembly, two additional devices have been designed: the economizer and air preheater. Such installation allows to reach the assembly efficiency of 82%. The research over the air nozzles placement in the combustion chamber in order to ensure the best firebox efficiency is also presented. Modeling is based on computational fluid dynamics simulations of pyrolysis on the moving grate. Released gases are being transported to the combustion chamber, mixed with air from the nozzles and combusted. Furthermore, the model assumes different distribution and composition of gases across the moving grate