Morelia, Mexico
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Das A.K.,University of Rochester | Das A.K.,Saha Institute of Nuclear Physics | Frenkel J.,University of Sao Paulo | Schubert C.,University of Morelia
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We study the behavior of the dynamical fermion mass when infrared divergences and mass shell singularities are present in a gauge theory. In particular, in the massive Schwinger model in covariant gauges we find that the pole of the fermion propagator is divergent and gauge dependent at one loop, but the leading singularities cancel in the quenched rainbow approximation. On the other hand, in physical gauges, we find that the dynamical fermion mass is finite and gauge independent at least up to one loop. © 2013 Elsevier B.V.

Verma M.P.,Electric Research Institute of Mexico | Mario Cesar Suarez A.,University of Morelia
Journal of Statistical Software | Year: 2014

The computer program DixonText.CriticalValues is written in VB.NET to extend the quadrature approach to calculate the critical values with accuracy up to 6 significant digits for Dixon's ratios. Its use in creating the critical values tables in Excel is illustrated.

Campos R.G.,University of Morelia
European Physical Journal Plus | Year: 2015

A Cauchy-type integral formula is used to obtain the value of a fractional derivative of a power function at the negative real axis. This new result highlights the lack of time-reversal symmetry of a fractional differential operator of noninteger order in Newtonian mechanics. © 2015, Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg.

Arteaga-Velazquez J.C.,University of Morelia
Journal of Physics: Conference Series | Year: 2015

The High Altitude Water Cherenkov (HAWC) observatory is a ground-based air- shower detector designed to study cosmic rays and gamma rays with energies from 100 GeV up to 100 TeV. HAWC simultaneously surveys 2sr of the northern sky with a high duty cycle > 90% in search for photons from point and extended sources, diffuse emission, transient events and other astrophysical phenomena at multi-TeV scales against the background of cosmic rays. In fact, the study of this background will open also the possibility of doing cosmic ray physics in the GeV - TeV regime and even to perform solar studies at HAWC. The observatory will consist of a densely packed array of 300 water Cherenkov tanks (4.5 m tall and 7.3 m diameter with 4 photomultipliers each) distributed on a 22 000 m2 surface. Deployment started in March 2012 on a plateau situated on the Sierra Negra Volcano in the state of Puebla, Mexico, at an altitude of 4100 m. Construction is expected to be finished by the first months of 2015. In the mean time, HAWC has been taking data with a partial array and preliminary results have been already obtained. In this contribution, the results from the latest HAWC observations will be presented. © Published under licence by IOP Publishing Ltd.

Wagner E.,University of Morelia
Journal of Physics: Conference Series | Year: 2016

Hilbert space representations of quantum SU(2) by multiplication operators on a local chart are constructed, where the local chart is given by tensor products of square integrable functions on a quantum disc and on the classical unit circle. The actions of generators of quantum SU(2), generators of the opposite algebra, and noncommutative partial derivatives are computed on a Hilbert space basis. © Published under licence by IOP Publishing Ltd.

Almaraz G.M.D.,University of Morelia
Materials Performance and Characterization | Year: 2015

Ultrasonic fatigue tests were carried out on the aluminum alloy AISI 6061-T6, presenting different values for the principal surface roughness parameters: Ra, Rq, and Rz. For fatigue life comprised between 3 × 105 ∼ 6 × 106 cycles, crack initiates at the specimen surface induced by stress-concentration and micro-plastic deformation (micro-void coalescence); whereas for the very high cycle fatigue (>107 cycles), the mechanism of crack initiation moves to subsurface or inside the specimen and is associated with internal imperfections such as micro-porosities or nonmetallic inclusions. For the first fatigue life regime, compression residual stresses induced by the work-hardening machining process and the associated micro-plastic deformation are the principal factors controlling the fatigue endurance on this aluminum alloy. Experimental results show that fatigue endurance is higher for the high surface roughness in the 3 × 105 ∼ 6 × 106 cycles of fatigue life, whereas this behavior is inversed in the very high-cycle fatigue regime. These results are analyzed in terms of residual compression stresses induced by the work-hardening machining process, the surface roughness, and the reverse yielding or Bauschinger effect. © 2015 by ASTM International.

In recent years eating disorders have increased their presence in Mexico. It has been suggested that internet and social network which promote restrictive behavior influence and may be responsible for this increment. Nowadays, internet plays a fundamental roll in the teaching-learning process and a very important tool in informal education, however, the use of internet and social network haven't been significantly related to the development of those eating disorders. On the other hand, one of the most accepted models about influential factors of the mentioned disorders leaves out the possibility that constant contact with these technology tools favors the development of anorexia and bulimia and other unspecified problems if we do not have the presence of other important factors.

Gonzalez-A G.,University of Morelia
Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering | Year: 2016

A bond graph model for a closed-loop linear time invariant multiple input multiple output system with singular perturbations is presented. This system is formed by a plant, an observer and the feedback. Hence, the storage elements that represent the slow dynamics of the observer determine the feedback control. Also, a junction structure of the bond graph model for the closed-loop system with singular perturbations is proposed. A new bond graph to obtain the observer and controller gains of the closed-loop system is presented. This new bond graph has the characteristic that storage elements of the fast dynamics and slow dynamics have a derivative and integral causality assignment, respectively. Thus, a quasi-steady state model of a singularly perturbed system with a slow state estimated feedback is obtained. Finally, the proposed methodology is applied to an illustrative example. © Institution of Mechanical Engineers 2016.

Campos R.G.,University of Morelia | Figueroa J.,University of Morelia
Signal Processing | Year: 2011

In recent years there has been a renewed interest in finding fast algorithms to compute accurately the linear canonical transform (LCT) of a given function. This is driven by the large number of applications of the LCT in optics and signal processing. The well-known integral transforms: Fourier, fractional Fourier, bilateral Laplace and Fresnel transforms are special cases of the LCT. In this paper we obtain an O(NlogN) algorithm to compute the LCT by using a chirp-FFT-chirp transformation yielded by a convergent quadrature formula for the fractional Fourier transform. This formula gives a unitary discrete LCT in closed form. In the case of the fractional Fourier transform the algorithm computes this transform for arbitrary complex values inside the unitary circle and not only at the boundary. This chirp-FFT-chirp transform approximates the ordinary Fourier transform more precisely than just the FFT, since it comes from a convergent procedure for non-periodic functions. © 2010 Elsevier B.V. All rights reserved.

Arteaga-Velazquez J.C.,University of Morelia
Astroparticle Physics | Year: 2012

The diffuse neutrino flux from FRI and BL Lac type galaxies generated from interactions of their own γ radiation with the gas and dust at the sources is reported. This ν-production channel has not been studied in detail up to now. The calculations are based on individual estimations of the neutrino flux in two nearby AGN's: Centaurus A and M87, assuming the validity of the AGN unification model. The predictions for Centaurus A and M87 involved the parameterization of the measured gamma-ray luminosities and the modeling of the material of the galaxies both based on observations performed by several detectors. No hadronic origin for the TeV photons is assumed. The results show that, although the corresponding ν flux ( E2Φν+ ν̄≲10 -13s- 1sr- 1GeVcm- 2) is not competitive at high-energies ( ν≳1TeV) with that from hadronic models, FRI and BL Lac galaxies with γ emission should be already contributing to the diffuse flux of neutrinos in the universe. © 2012 Elsevier B.V. All rights reserved.

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