Detailed atmospheric abundance analysis of the optical counterpart of the IR source IRAS 16559-2957

We have undertaken a detailed abundance analysis of the optical counterpart of the IR source IRAS16559-2957 with the aim of confirming its possible post-AGB nature. The star shows solar metallicity and our investigation of a large number of elements including CNO and 12C/13C suggests that this object has experienced the first dredge-up and it is likely still at RGB stage.Comment: 10 pages, 4 figures, 4 tables. To be published by Revista Mexicana de Astronomia y Astrofisica, April 201

Prediction of jet engine parameters for control design using genetic programming

The simulation of a jet engine behavior is widely used in many different aspects of the engine development and maintenance. Achieving high quality jet engine control systems requires the iterative use of these simulations to virtually test the performance of the engine avoiding any possible damage on the real engine. Jet engine simulations involve the use of mathematical models which are complex and may not always be available. This paper introduces an approach based on Genetic Programming (GP) to model different parameters of a small engine for control design such as the Exhaust Gas Temperature (EGT). The GP approach has no knowledge of the characteristics of the engine. Instead, the model is found by the evolution of models based on past measurements of parameters such as the pump voltage. Once the model is obtained, it is used to predict the behaviour of the jet engine one step ahead. The proposed approach is successfully applied for the simulation of a Behotec j66 jet engine and the results are presented

UNDERWATER DOLPHIN KICKING IN STARTS AND TURNS

Our studies related with underwater dolphin kicking helped us to understand the complexity of this propulsive action (applying kinematic analysis and flow visualization) to develop more appropriate prescriptive information to be applied in application of this technique in the performances of national and international swimmers. Under the rules limitations (15m), the swimmers can apply properly this technique and reduce the starting time until times close to 5 s. (considered impossible in the past). New swimsuit technology improves particularly the performance in this technique. Some aspects need to be considered based on our research in this technique: a) when start the dolphin kick after the start or turn [how long should glide]; b) influence of the previous gliding velocity; c) undulating or oscillating; d) influence of the morphological factors; e) different models and variables to measure its efficiency; f) how long should keep the dolphin kick and; g) when to finish the dolphin kicking. In our talk we will try to advice on the aspects mentioned and to show the kind of methodology we are applying to improve the use of this technique to the Spanish swimmers

Physical parameters of three field RR Lyrae stars

This work was partially supported by DGAPA–Universidad Nacional Autonoma de Mexico through project IN104612.Stromgren uvby - beta photometry of the stars classified as RR Lyrae stars RU Piscium, SS Piscium and TU Ursae Majoris has been used to estimate their iron abundance, temperature, gravity and absolute magnitude. The stability of the pulsating period is discussed. The nature of SS Psc as a RRc or a HADS is addressed. The reddening of each star is estimated from the Stromgren colour indices and reddening sky maps. The results of three approaches to the determination of [Fe/H], T-eff and log(g) are discussed: Fourier light curve decomposition, the Preston Delta S index and the theoretical grids on the (b - y)(o) - c(10) plane.Peer reviewe

Non-Gaussian Geostatistical Modeling using (skew) t Processes

We propose a new model for regression and dependence analysis when addressing spatial data with possibly heavy tails and an asymmetric marginal distribution. We first propose a stationary process with $t$ marginals obtained through scale mixing of a Gaussian process with an inverse square root process with Gamma marginals. We then generalize this construction by considering a skew-Gaussian process, thus obtaining a process with skew-t marginal distributions. For the proposed (skew) $t$ process we study the second-order and geometrical properties and in the $t$ case, we provide analytic expressions for the bivariate distribution. In an extensive simulation study, we investigate the use of the weighted pairwise likelihood as a method of estimation for the $t$ process. Moreover we compare the performance of the optimal linear predictor of the $t$ process versus the optimal Gaussian predictor. Finally, the effectiveness of our methodology is illustrated by analyzing a georeferenced dataset on maximum temperatures in Australi

Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalent NN potentials

The sensitivity of nucleon-nucleus elastic scattering to the off-shell behavior of realistic nucleon-nucleon interactions is investigated when on-shell equivalent nucleon-nucleon potentials are used. The study is based on applications of the full-folding optical model potential for an explicit treatment of the off-shell behavior of the nucleon-nucleon effective interaction. Applications were made at beam energies between 40 and 500 MeV for proton scattering from 40Ca and 208Pb. We use the momentum-dependent Paris potential and its local on-shell equivalent as obtained with the Gelfand-Levitan and Marchenko inversion formalism for the two nucleon Schroedinger equation. Full-folding calculations for nucleon-nucleus scattering show small fluctuations in the corresponding observables. This implies that off-shell features of the NN interaction cannot be unambiguously identified with these processes. Inversion potentials were also constructed directly from NN phase-shift data (SM94) in the 0-1.3 GeV energy range. Their use in proton-nucleus scattering above 200 MeV provide a superior description of the observables relative to those obtained from current realistic NN potentials. Limitations and scope of our findings are presented and discussed.Comment: 17 pages tightened REVTeX, 8 .ps figures, submitted to Phys. Rev.

Gate induced enhancement of spin-orbit coupling in dilute fluorinated graphene

We analyze the origin of spin-orbit coupling (SOC) in fluorinated graphene using Density Functional Theory (DFT) and a tight-binding model for the relevant orbitals. As it turns out, the dominant source of SOC is the atomic spin-orbit of fluorine adatoms and not the impurity induced SOC based on the distortion of the graphene plane as in hydrogenated graphene. More interestingly, our DFT calculations show that SOC is strongly affected by both the type and concentrations of the graphene's carriers, being enhanced by electron doping and reduced by hole doping. This effect is due to the charge transfer to the fluorine adatom and the consequent change in the fluorine-carbon bonding. Our simple tight-binding model, that includes the SOC of the $2p$ orbitals of F and effective parameters based on maximally localized Wannier functions, is able to account for the effect. The strong enhancement of the SOC induced by graphene doping opens the possibility to tune the spin relaxation in this material.Comment: 9 pages, 8 figure