Metodología para la restauración y puesta en marcha de una máquina fresadora CNC

The Computerized Numerical Control (CNC) is a technology that allows, through the use of a computer, to control and monitor the movements of a machine tool. The Superior Technological Institute of San Andrés Tuxtla (ITSSAT) has a CNC milling machine tool with European technology acquired by the state government in 2003 for engineering student practices. The machine was obsolete and out of operation, a situation that obligates not to use the CNC in practice for a while since the industries that manufacture them use licensed software and electronic cards that have a high cost for repair. The purpose of this article is to present a methodology for the restoration and start-up of CNC machines without having to resort to the manufacturer. The results show the methodology whose main function is the communication of the CNC machine with the PC through the implementation of the alternate software Mach 3 and the electronic card LPT-Mach 3 achieving the operation of the machine and the milling of materials with academic and industrial purposes.El Control Numérico Computarizado (CNC) es una tecnología que permite mediante el uso de una computadora controlar y monitorear los movimientos de una máquina herramienta. El Instituto Tecnológico Superior de San Andrés Tuxtla (ITSSAT) cuenta con una máquina herramienta fresadora CNC con tecnología europea adquirida por el gobierno del Estado en el 2003 para prácticas de los estudiantes de ingeniería. La máquina se encontraba obsoleta y sin funcionamiento, situación que provoco no hacer uso de la CNC en las prácticas durante un tiempo, ya que las industrias que las fabrican utilizan software con licencia y tarjetas electrónicas que tienen un costo elevado para su reparación. El presente artículo tiene como finalidad dar a conocer una metodología para la restauración y puesta en marcha de la máquina fresadora CNC sin necesidad de recurrir al fabricante. Los resultados muestran la metodología cuya principal función es la comunicación de la máquina CNC con la PC mediante la implementación del software alterno Mach 3 y la tarjeta electrónica LPT-Mach 3 logrando el funcionamiento de la máquina y con ello el fresado de materiales con fines académicos e industriales

Nonlocal Transport Processes and the Fractional Cattaneo-Vernotte Equation

The Cattaneo-Vernotte equation is a generalization of the heat and particle diffusion equations; this mathematical model combines waves and diffusion with a finite velocity of propagation. In disordered systems the diffusion can be anomalous. In these kinds of systems, the mean-square displacement is proportional to a fractional power of time not equal to one. The anomalous diffusion concept is naturally obtained from diffusion equations using the fractional calculus approach. In this paper we present an alternative representation of the Cattaneo-Vernotte equation using the fractional calculus approach; the spatial-time derivatives of fractional order are approximated using the Caputo-type derivative in the range (0,2]. In this alternative representation we introduce the appropriate fractional dimensional parameters which characterize consistently the existence of the fractional space-time derivatives into the fractional Cattaneo-Vernotte equation. Finally, consider the Dirichlet conditions, the Fourier method was used to find the full solution of the fractional Cattaneo-Vernotte equation in analytic way, and Caputo and Riesz fractional derivatives are considered. The advantage of our representation appears according to the comparison between our model and models presented in the literature, which are not acceptable physically due to the dimensional incompatibility of the solutions. The classical cases are recovered when the fractional derivative exponents are equal to 1

de Sitter Thick Brane Solution in Weyl Geometry

In this paper, we consider a de Sitter thick brane model in a pure geometric Weyl integrable five-dimensional space-time, which is a generalization of Riemann geometry and is invariant under a so-called Weyl rescaling. We find a solution of this model via performing a conformal transformation to map the Weylian structure into a familiar Riemannian one with a conformal metric. The metric perturbations of the model are discussed. For gravitational perturbation, we get the effective modified P$\ddot{\text{o}}$schl-Teller potential in corresponding Schr$\ddot{\text{o}}$dinger equation for Kaluza-Klein (KK) modes of the graviton. There is only one bound state, which is a normalizable massless zero mode and represents a stable 4-dimensional graviton. Furthermore, there exists a mass gap between the massless mode and continuous KK modes. We also find that the model is stable under the scalar perturbation in the metric. The correction to the Newtonian potential on the brane is proportional to $e^{-3 r \beta/2}/r^2$, where $\beta$ is the de Sitter parameter of the brane. This is very different from the correction caused by a volcano-like effective potential.Comment: 24 pages, 13 figures, published versio

Adaptive fractional PID control of biped robots with time-delayed feedback

This paper presents the application of Fractional Order Time- Delay adaptive neural networks to the trajectory tracking for chaos synchronization between Fractional Order delayed plant, reference and Fractional Order Time-Delay adaptive neural networks. The proposed new control scheme is applied via simulations to control of a 4-DOF Biped Robot [1]. The main methodologies, on which the approach is based, are Fractional Order PID the Fractional Order Lyapunov-Krasovskii functions methodology. The structure of the biped robot is designed with two degrees of freedom per leg, corresponding to the knee and hip joints. Since torso and ankle are not considered, it is obtained a 4-DOF system, and each leg, we try to force this biped robot to track a reference signal given by undamped Duffing equation. The tracking error is globally asymptotically stabilized by two control laws derived based on a Lyapunov-Krasovski functional

Effects of temperature on thick branes and the fermion (quasi-)localization

Following Campos's work [Phys. Rev. Lett. 88, 141602 (2002)], we investigate the effects of temperature on flat, de Sitter (dS), and anti-de Following Campos's work [Phys. Rev. Lett. \textbf{88}, 141602 (2002)], we investigate the effects of temperature on flat, de Sitter (dS), and anti-de Sitter (AdS) thick branes in five-dimensional (5D) warped spacetime, and on the fermion (quasi-)localization. First, in the case of flat brane, when the critical temperature reaches, the solution of the background scalar field and the warp factor is not unique. So the thickness of the flat thick brane is uncertain at the critical value of the temperature parameter, which is found to be lower than the one in flat 5D spacetime. The mass spectra of the fermion Kaluza-Klein (KK) modes are continuous, and there is a series of fermion resonances. The number and lifetime of the resonances are finite and increase with the temperature parameter, but the mass of the resonances decreases with the temperature parameter. Second, in the case of dS brane, we do not find such a critical value of the temperature parameter. The mass spectra of the fermion KK modes are also continuous, and there is a series of fermion resonances. The effects of temperature on resonance number, lifetime, and mass are the same with the case of flat brane. Last, in the case of AdS brane, {the critical value of the temperature parameter can less or greater than the one in the flat 5D spacetime.} The spectra of fermion KK modes are discrete, and the mass of fermion KK modes does not decrease monotonically with increasing temperature parameter.Comment: 24 pages, 15 figures, published versio

Beneficios en la calidad de vida de un programa de cribado y tratamiento de apnea obstructiva del sueño en pacientes con ictus isquémico agudo

[Introducción] La apnea obstructiva del sueño (AOS) se ha propuesto como un factor de mal pronóstico en el ictus. Pretendemos determinar si una intervención sobre la AOS puede mejorar las escalas de calidad de vida (primer objetivo) y de discapacidad (segundo objetivo).[Pacientes y métodos] El grupo de intervención de este estudio cuasi experimental incluye a pacientes con ictus isquémico agudo < 72 horas de evolución a quienes se les realizó poligrafía, así como presión positiva continua en las vías aéreas (CPAP) y medidas higienicodietéticas si se requerían. En el grupo de control se siguió la práctica clínica habitual. Se aplicaron las escalas Short Form 36 Health Survey (SF-36) y modified Rankin Score (mRS) en el sexto mes del ictus en ambos grupos.[Resultados] Se incluyó a 55 y a 62 pacientes en el grupo de intervención y en el de control, respectivamente. En el grupo de intervención, el 64,71% de los pacientes aceptó la CPAP indicada (16 casos con buena adhesión). Se detectó una mejoría en los ítems de la escala SF-36 en el grupo de intervención: funcionamiento físico (p = 0,008), rol físico (p = 0,002), dolor corporal (p = 0,008), salud general (p < 0,001), vitalidad (p = 0,001) y rol emocional (p = 0,015). En un análisis por protocolo, todas estas mejorías se comprobaron en el grupo de pacientes tratados con CPAP con buena adhesión (p < 0,05 en todos los ítems de la SF-36). El porcentaje de pacientes con el sumatorio del componente físico = 50 fue más alto en el grupo de intervención (p = 0,003). No había diferencias en la mediana de la mRS (p = 0,262).[Conclusiones] Aunque se necesitan más evidencias, nuestro estudio sugiere una mejoría significativa de la calidad de vida tras nuestra intervención en la AOS, especialmente en pacientes con buena adhesión a la CPAP.Peer reviewe

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Evolutionary and pulsational properties of white dwarf stars

Abridged. White dwarf stars are the final evolutionary stage of the vast majority of stars, including our Sun. The study of white dwarfs has potential applications to different fields of astrophysics. In particular, they can be used as independent reliable cosmic clocks, and can also provide valuable information about the fundamental parameters of a wide variety of stellar populations, like our Galaxy and open and globular clusters. In addition, the high densities and temperatures characterizing white dwarfs allow to use these stars as cosmic laboratories for studying physical processes under extreme conditions that cannot be achieved in terrestrial laboratories. They can be used to constrain fundamental properties of elementary particles such as axions and neutrinos, and to study problems related to the variation of fundamental constants. In this work, we review the essentials of the physics of white dwarf stars. Special emphasis is placed on the physical processes that lead to the formation of white dwarfs as well as on the different energy sources and processes responsible for chemical abundance changes that occur along their evolution. Moreover, in the course of their lives, white dwarfs cross different pulsational instability strips. The existence of these instability strips provides astronomers with an unique opportunity to peer into their internal structure that would otherwise remain hidden from observers. We will show that this allows to measure with unprecedented precision the stellar masses and to infer their envelope thicknesses, to probe the core chemical stratification, and to detect rotation rates and magnetic fields. Consequently, in this work, we also review the pulsational properties of white dwarfs and the most recent applications of white dwarf asteroseismology.Comment: 85 pages, 28 figures. To be published in The Astronomy and Astrophysics Revie