Estudio estadístico del potencial eólico del Cerro de la Virgen en Zacatecas, México

La capacidad instalada de energía en eólica en México, a finales del 2013, es de 1,917 MW, distribuida en 26 parques en 6 estados, donde Oaxaca representa más del 90% de capacidad instalada. En el presente trabajo se evalúan cinco métodos numéricos para la estimación de los parámetros de la función de distribución de Weibull, utilizando datos recabados por una estación meteorológica ubicada en el “Cerro de la Virgen” del estado de Zacatecas, durante un periodo de seis meses. La evaluación estadística se realiza por RMSE (error medio cuadrático) y 2 X (chi cuadrado), donde los métodos basados en iteraciones numéricas presentan el mejor ajuste al histograma de velocidad de viento. Se observa, que el método de la máxima verosimilitud es más preciso, a partir del cual se estima el potencial eólico del sitio, obteniendo resultados prometedores para el desarrollo de proyectos basados en esta fuente alterna de energía

Estudio estadístico del potencial eólico del Cerro de la Virgen en Zacatecas, México

La capacidad instalada de energía en eólica en México, a finales del 2013, es de 1,917 MW, distribuida en 26 parques en 6 estados, donde Oaxaca representa más del 90% de capacidad instalada. En el presente trabajo se evalúan cinco métodos numéricos para la estimación de los parámetros de la función de distribución de Weibull, utilizando datos recabados por una estación meteorológica ubicada en el “Cerro de la Virgen” del estado de Zacatecas, durante un periodo de seis meses. La evaluación estadística se realiza por RMSE(error medio cuadrático) y 2 X (chi cuadrado), donde los métodos basados en iteraciones numéricas presentan el mejor ajuste al histograma de velocidad de viento. Se observa, que el método de la máxima verosimilitud es más preciso, a partir del cual se estima el potencial eólico del sitio, obteniendo resultados  prometedores para el desarrollo de proyectos basados en esta fuente alterna de energía

Mejoramiento de películas delgadas de CdTe/CdS mediante activación húmeda de CdCl2 en una atmósfera de aire para aplicaciones en celdas solares

Solar cells based on CdTe/CdS thin films are some of the most promising photovoltaic devices due to their high theoretical conversion value of 29%. Typical problems associated with CdTe/CdS polycrystalline thin films are porosity, and non-uniform surfaces and interfaces. These defects facilitate the recombination of charge carriers decreasing the conversion efficiency. In this work, a CdS thin film is deposited by the chemical bath method (CBD) over a glass substrate with a thin layer of flour-doped tin oxide (FTO). The CdS thin film is activated using CdCl2 diluted in methanol inside a furnace at a certain temperature and in an air atmosphere. The objective of the activation process is to reduce the structural defects of the film and achieve a homogeneous surface. The CdTe film is deposited using the close space sublimation technique (CSS) and is activated using CdCl2. To find the optimum values of the activation process, the concentrations of CdCl2, the immersion time, the annealing temperature and annealing time are varied. The thin films and the conversion efficiency are evaluated as a function of the activation process. After activation, the thin films indicate an increase in conversion efficiency.Las celdas solares basadas en CdTe/CdS están entre los dispositivos fotovoltaicos más prometedores por su alto valor teórico de conversión de energía de 29%. Problemas comunes asociados con películas delgadas policristalinas de CdTe/CdS son la porosidad y superficies no uniformes. Estos defectos facilitan el proceso de recombinación de portadores de carga y reducen la eficiencia de conversión. En este trabajo se deposita una película de CdS mediante el método de baño químico (CBD) sobre un sustrato de vidrio con oxido de estaño dopado con flúor (FTO). La película de CdS se activa usando CdCl2 diluido en metanol dentro de un horno a cierta temperatura y en una atmosfera de aire. El objetivo es reducir las imperfecciones de la película y lograr una superficie homogénea. La película de CdTe se deposita mediante la técnica de sublimación en espacio cercano (CSS) y es sometida a activación con CdCl2. Para encontrar los valores óptimos de activación se varían las concentraciones de CdCl2, el tiempo de inmersión, la temperatura de recocido y el tiempo de recocido. Se evalúan las películas y la eficiencia alcanzada en función del proceso de activación. Las películas sometidas ha este proceso muestran un aumento en la eficiencia de conversión

Slotine-Li Adaptable Controller Design for 2 gdl Robot and Continuous Trajectory Simulation

This paper presents the analysis of the mathematical model to obtain the dynamic model of a robot with two degrees of freedom (translational, rotational), after which an adaptable Slotine-Li controller was designed and applied. In this investigation the fundamental purpose is to demonstrate the efficiency of Slotine-Li's adaptive controller since it allows the system to be controlled despite slow variations in time or due to ignorance of the parameters of the robot's mathematical model. In addition to that the controller is able to estimate the parameters that are unknown with very good approximation. We also programmed the follow-up of a continuous path in the form of an ellipse to verify the efficiency of the adaptive controller and the simulation of the tracking of the same was done using VisSim 6.0.En el presente documento se muestra el análisis del modelo matemático para obtener el modelo dinámico de un robot de dos grados de libertad (traslacional, rotacional), posteriormente se diseñó y aplicó un controlador adaptable de Slotine-Li. El propósito fundamental de esta investigación, es demostrar la eficacia del controlador adaptable de Slotine-Li, ya que permite que el sistema sea controlado a pesar de variaciones lentas en el tiempo o por desconocimiento de alguno de los parámetros del modelo matemático del robot. Además de que este tipo de controlador es capaz de estimar los parámetros que se desconocen con muy buena aproximación. También se realizó el seguimiento de una trayectoria continua para verificar la eficiencia del controlador adaptable y la simulación del seguimiento de la misma, se realizó utilizando el software VisSim 6.

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV

The production of b jets in association with a Z/gamma* boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector. The inclusive cross section for Z/gamma* + b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross section with Z/gamma* to ll (where ll = ee or mu mu) for events with the invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.) +(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by PYTHIA.Comment: Submitted to the Journal of High Energy Physic

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