Optimization Techniques for the Power Beaming Analysis of Microwave Transmissions from a Space-Based Solar Power Satellite

In the 21st century, the development of technologies to produce carbon free power sources remains paramount. In this paper, we study an optimal power transmission strategy from a space-based satellite generation station to Earth using scalar diffraction theory. The resulting model is then solved via a spectral method that guarantees a compactly supposed profile from the transmitting antenna. Finally, the problem is then solved via a more general pseudo-spectral method using control theory

Evaluation of a series hybird thrust bearing at DN values to three million. 1: Analysis and design

The analysis and design are presented of a hybrid bearing consisting of a 150-mm ball bearing and a centrifugally actuated, conical, fluid film bearing fitting an envelope with an outer radius of 86.4 mm (3.4 in.) and an inner radius of 71 mm (2.8 in.). The bearing analysis, combined with available torque data on ball bearings, indicates that an effective speed split between the ball and fluid-film bearings of 50 percent may be expected during operation at 20,000 rpm and under an axial load of 17,800 newtons (4000 lbs.). This speed split can result in a ten-fold increase in the life of the ball bearing when compared to a simple ball bearing system operating under similar conditions

Radiative Neutrino Mass, Dark Matter and Leptogenesis

We propose an extension of the standard model, in which neutrinos are Dirac particles and their tiny masses originate from a one-loop radiative diagram. The new fields required by the neutrino mass-generation also accommodate the explanation for the matter-antimatter asymmetry and dark matter in the universe.Comment: 4 pages, 3 figures. Revised version with improved model. Accepted by PR

Neutrino masses, leptogenesis and dark matter in hybrid seesaw

We suggest a hybrid seesaw model where relatively ``light''right-handed neutrinos give no contribution to the neutrino mass matrix due to a special symmetry. This allows their Yukawa couplings to the standard model particles to be relatively strong, so that the standard model Higgs boson can decay dominantly to a left and a right-handed neutrino, leaving another stable right-handed neutrino as cold dark matter. In our model neutrino masses arise via the type-II seesaw mechanism, the Higgs triplet scalars being also responsible for the generation of the matter-antimatter asymmetry via the leptogenesis mechanism.Comment: 4 page

Glassy Dynamics in a Frustrated Spin System: Role of Defects

In an effort to understand the glass transition, the kinetics of a spin model with frustration but no quenched randomness has been analyzed. The phenomenology of the spin model is remarkably similiar to that of structural glasses. Analysis of the model suggests that defects play a major role in dictating the dynamics as the glass transition is approached.Comment: 9 pages, 5 figures, accepted in J. Phys.: Condensed Matter, proceedings of the Trieste workshop on "Unifying Concepts in Glass Physics

Resonant Leptogenesis and Verifiable Seesaw from Large Extra Dimensions

In the presence of large extra dimensions, the fundamental scale could be as low as a few TeV. This yields leptogenesis and seesaw at a TeV scale. Phenomenologically two TeV-scale Majorana fermions with a small mass split can realize a resonant leptogenesis whereas a TeV-scale Higgs triplet with a small trilinear coupling to the standard model Higgs doublet can give a verifiable seesaw. We propose an interesting scenario where the small parameters for the resonant leptogenesis and the type-II seesaw can be simultaneously generated by the propagation of lepton number violation from distant branes to our world.Comment: 5 pages. More discussions and references. Published in PR

Spectral Analyses of the Nearest Persistent Ultraluminous X-Ray Source M33 X-8

We provide a detailed analysis of 12 XMM observations of the nearest persistent extragalactic ultraluminous X-ray source (ULX), M33 X-8. No significant spectral evolution is detected between the observations, therefore we combine the individual observations to increase the signal-to-noise ratio for spectral fitting. The combined spectra are best fitted by the self-consistent p-free disk plus power-law component model with p = 0.571_{-0.030}^{+0.032}, kT_{in} = 1.38_{-0.08}^{+0.09} keV, and the flux ratio of the p-free disk component to the power-law component being 0.63:0.37 in the 0.3 -- 10 keV band. The fitting indicates that the black hole in M33 X-8 is of \sim 10 M_{\odot} and accretes at a super-Eddington rate (\sim 1.5 L_{Edd}), and the phase of the accretion disk is close to a slim disk (p = 0.5). We report, for the first time, that an extra power-law component is required in addition to the p-free disk model for ULXs. In super-Eddington cases, the power-law component may possibly result from the optically thin inner region f the disk or a comptonized corona similar to that of a standard thin disk.Comment: 11 pages, 1 table, 2 figures, accepted by PAS