The use of tethers for payload orbital transfer. Continuation of investigation of electrodynamic stabilization and control of long orbiting tethers, volume 2

The SKYHOOK program was used to do simulations of two cases of the use of the tether for payload orbital transfer. The transport of a payload along the tether from a heavy lower platform to an upper launching platform is considered. A numerical example of the Shuttle launching a payload using an orbital tether facility is described

Renormalization Group and Grand Unification with 331 Models

By making a renormalization group analysis we explore the possibility of having a 331 model as the only intermediate gauge group between the standard model and the scale of unification of the three coupling constants. We shall assume that there is no necessarily a group of grand unification at the scale of convergence of the couplings. With this scenario, different 331 models and their corresponding supersymmetric versions are considered, and we find the versions that allow the symmetry breaking described above. Besides, the allowed interval for the 331 symmetry breaking scale, and the behavior of the running coupling constants are obtained. It worths saying that some of the supersymmetric scenarios could be natural frameworks for split supersymmetry. Finally, we look for possible 331 models with a simple group at the grand unification scale, that could fit the symmetry breaking scheme described above.Comment: 18 pages. 3 figures. Some results reinterpreted, a new section and references added. Version to appear in International Journal of Modern Physics

The ferroelectric Mott-Hubbard phase of organic (TMTTF)2X conductors

We present experimental evidences for a ferro-electric transition in the family of quasi one- dimensional conductors (TMTTF)2X. We interpret this new transition in the frame of the combined Mott-Hubbard state taking into account the double action of the spontaneous charge disproportionation on the TMTTF molecular stacks and of the X anionic potentials

(In-)Significance of the Anomalous Magnetic Moment of Charged Fermions for the Equation of State of a Magnetized and Dense Medium

We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EoS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (eB>m^2) the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EoS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EoS at any field value.Comment: More detailed figure

Voltage dip generator for testing wind turbines connected to electrical networks

This paper describes a new voltage dip generator that allows the shape of the time profile of the voltage generated to be configured. The use of this device as a tool to test the fault ride-through capability of wind turbines connected to the electricity grid can provide some remarkable benefits: First, this system offers the possibility of adapting the main features of the time–voltage profile generated (dip depth, dip duration, the ramp slope during the recovery process after clearing fault, etc.) to the specific requirements set forth by the grid operation codes, in accordance with different network electrical systems standards. Second, another remarkable ability of this system is to provide sinusoidal voltage and current wave forms during the overall testing process without the presence of harmonic components. This is made possible by the absence of electronic converters. Finally, the paper includes results and a discussion on the experimental data obtained with the use of a reduced size laboratory prototype that was constructed to validate the operating features of this new device

Resonant electron transmission through a finite quantum spin chain

Electron transport in a finite one dimensional quantum spin chain (with ferromagnetic exchange) is studied within an $s-d$ exchange Hamiltonian. Spin transfer coefficients strongly depend on the sign of the $s-d$ exchange constant. For a ferromagnetic coupling, they exhibit a novel resonant pattern, reflecting the salient features of the combined electron-spin system. Spin-flip processes are inelastic and feasible at finite voltage or at finite temperature.Comment: 4 pages including 4 .eps figure