Diseño de una estructura móvil para un panel solar de 205 w con dos grados de libertad

Este documento presenta la realización de una estructura móvil para un módulo fotovoltaico diseñado para desplazarse en dos grados de libertad, resistir cargas de viento y soportar condiciones externas. La estructura es controlada inalámbricamente por medio de una interfaz de usuario donde este determina la posición de él ángulo acimut o inclinación que desea desplazar ingresando valores de ángulos dentro de un rango permitido para cada uno de los movimientos, el sistema se comunica con un control de motores el cual ha sido diseñado en lazo abierto y con alta precisión mecánica para permitir lograr ángulos enteros con desplazamientos mínimos de un grado, el sistema de control de motores es alimentado por una batería la cual es cargada por un panel solar.This paper presents the implementation of a mobile structure for a photovoltaic module designed to move in two degrees of freedom, to resist wind loads and withstand external conditions. The structure is wirelessly controlled by a user interface where this determines the position of azimuth angle or inclination to be moved entering angle values within a range allowed for each of the movements, the system communicates with a control engine which has been designed in open loop and with a mechanical precision to allow integer angles achieve minimum displacement of a degree, the motor control system is powered by a battery which is charged by a solar panel.Ingeniero (a) ElectrónicoPregrad

Towards a general analysis of LHC data within two-Higgs-doublet models

The data accumulated so far confirm the Higgs-like nature of the new boson discovered at the LHC. The Standard Model Higgs hypothesis is compatible with the collider results and no significant deviations from the Standard Model have been observed neither in the flavour sector nor in electroweak precision observables. We update the LHC and Tevatron constraints on CP-conserving two-Higgs-doublet models without tree-level flavour-changing neutral currents. While the relative sign between the top Yukawa and the gauge coupling of the 126 GeV Higgs is found be the same as in the SM, at 90% CL, there is a sign degeneracy in the determination of its bottom and tau Yukawa couplings. This results in several disjoint allowed regions in the parameter space. We show how generic sum rules governing the scalar couplings determine the properties of the additional Higgs bosons in the different allowed regions. The role of electroweak precision observables, low-energy flavour constraints and LHC searches for additional scalars to further restrict the available parameter space is also discussed

LHC constraints on two-Higgs doublet models

A new Higgs-like boson with mass around 126 GeV has recently been discovered at the LHC. The available data on this new particle is analyzed within the context of two-Higgs doublet models without tree-level flavour-changing neutral currents. Keeping the generic Yukawa structure of the Aligned Two-Higgs Doublet Model framework, we study the implications of the LHC data on the allowed scalar spectrum. We analyze both the CP-violating and CP-conserving cases, and a few particular limits with a reduced number of free parameters, such as the usual models based on discrete Z2 symmetries

Effectiveness and utility of acoustic recordings for surveying tropical birds

Although acoustic recordings have recently gained popularity as an alternative to point counts for surveying birds, little is known about the relative performance of the two methods for detecting tropical bird species across multiple vegetation types. During June and July 2008, we collected species detection/nondetection data to compare the performance of a quadraphonic acoustic recording system and point counts for estimating species richness and composition and detection probabilities of 15 rare, moderately common, and common tropical bird species across six structurally distinct vegetation types (coastal dune scrub, mangrove, low-stature deciduous thorn forest, early and late successional medium-stature semievergreen forest, and grazed pastures) in the northern Yucatan Peninsula.We selected five rare species endemic to the Yucatan Peninsula and 10 moderately common and common species that also occur in other tropical regions. Species richness and composition did not differ between survey methods in any of the vegetation types. At the population level, however, we found support for an effect of method on detection probability for most species. For 13 species, regardless of their abundance, acoustic recordings yielded detection probabilities as high as or higher than those for point counts across all vegetation types. The remaining two species were better detected by point counts in pastures and coastal scrub, where greater visibility likely improved sightings of these species. However, these species were detected as well as or better by acoustic recordings in forests and mangroves where detections were primarily auditory. In tropical regions where experienced field observersmay not be available and funding for field surveys may be limited, acoustic recordings offer a practical solution for determining species richness and composition and the occupancy patterns of most species. However, for some species, a combination of methods will provide the most reliable data. Regardless of the method selected, analyses that account for variation in detection probability among vegetation types will be necessary because most species in our study demonstrated vegetation-dependent detection probabilities

Implementación del ciclo de Deming para mejorar la calidad de atención del personal de seguridad del aeropuerto Jorge Chávez, Callao, 2017

La presente investigación, “Implementación del Ciclo de Deming para mejorar la calidad de atención del personal de seguridad del Aeropuerto Jorge Chávez”, tuvo como objetivo general determinar como el ciclo de Deming mejora la calidad en la atención del personal de seguridad en el aeropuerto Jorge Chávez. Dicha investigación fue de tipo aplicada, cuantitativa, y obedece a un diseño cuasi-experimental. La recolección de datos fue a través de la observación, realizada seis meses antes y seis meses posteriores a la implementación del ciclo de Deming. Asimismo, la población estuvo dada por los pasajeros que utilizan el Aeropuerto Internacional Jorge Chávez. Se realizó el análisis descriptivo sobre una muestra de la población y del total de quejas y reclamos; además, se realizó el análisis inferencial para la contrastación de las hipótesis. Finalmente, los resultados de la implementación del ciclo de Deming indicó que se mejoró la calidad de atención del personal de seguridad del Aeropuerto Jorge Chávez, y de acuerdo a la contrastación de la hipótesis general, se aceptó dicha hipótesis “La aplicación del ciclo de Deming mejora la calidad en la atención del personal de seguridad en el Aeropuerto Jorge Chávez”, de julio a diciembre de 2016

Control interno y gestión documentaria con respecto a la emisión de comprobantes de pago electrónicos en la empresa Nicoll Perú S.A., Lima 2016

El título del estudio que se presenta “Control interno y gestión documentaria con respecto a la emisión de comprobantes de pago electrónicos en la empresa Nicoll Perú S.A., Lima 2016” tuvo como objetivo principal determinar si el control interno se relaciona con la gestión documentaria al respecto a la emisión de comprobantes de pago electrónicos. El tipo de investigación del estudio fue descriptivo – correlacional – básica, considerando el diseño como no experimental – transversal. Para la población y la muestra se han considerado 15 colaboradores que son las personas que desempeñan en el área donde se ha aplicado el estudio. El instrumento está basado en la encuesta ya que es de esta manera se podrá llegar a la problemática del estudio. En relación, los objetivos planteados en la investigación han sido alcanzados en su integridad, como también los datos encontrados facilitaron el llegar a una conclusión para luego pasar a una recomendación, se puede asegurar haber solucionado si no en forma total gran parte de los problemas investigados. Finalmente, el estudio científico concluye que el control interno es de suma importancia en la gestión documentaria con respecto a la emisión de comprobantes de pago electrónicos

Extrapair mating behaviors in the field sparrow: nocturnal singing and extraterritorial forays

While there has been much research on the mating behaviors of birds, most attention has focused on elaborate and/or conspicuous mating displays, such as diurnal songs, ornaments, or mating dances. Much less attention has been devoted to investigating the role of more subtle behaviors, particularly nocturnal signing by diurnal birds and extra-territorial forays (movements off territory). My research explored the function of nocturnal singing and extra-territorial forays in the Field Sparrow (Spizella pusilla). I determined that nocturnal complex song serves to announce the presence of extra-pair males to females and that extra-territorial forays serve primarily in prospecting and soliciting extra-pair matings. While forays are common among both male and female Field Sparrows, a higher foraying rate did not result in greater extra-pair paternity (EPP). Rather, my data provide strong evidence that extra-pair matings are determined by current and previous relationships; females chose extra-pair sires that were current neighbors or neighbors or social mates during previous breeding seasons. Given female preference for extra-pair matings with neighbors, males who have information on the fertility status of neighboring females and coordinate their nocturnal vocalizations in relation to the fertility stage of neighboring females may be able to increase their EPP. Contrary to other studies, I did not find a relationship between the traits of males, females, or females’ social mates (age and tarsus length) and EPP. Thus, proximity to females, rather than male characteristics, appears to be key for a male’s success at acquiring extra-pair paternity. Finally, my findings are consistent with the hypothesis that female choice for extra-pair mates coupled with female foray behavior are driving patterns of extra-pair paternity and nocturnal singing behavior. By integrating research on nocturnal singing, extra-territorial foray behavior, and extra-pair paternity, my work has led to a more comprehensive understanding of extra-pair mating behavior in birds

FPGA implementation of an image recognition system based on tiny neural networks and on-line reconfiguration

Neural networks are widely used in pattern recognition, security applications and robot control. We propose a hardware architecture system; using Tiny Neural Networks (TNN) specialized in image recognition. The generic TNN architecture allows expandability by means of mapping several Basic units (layers) and dynamic reconfiguration; depending on the application specific demands. One of the most important features of Tiny Neural Networks (TNN) is their learning ability. Weight modification and architecture reconfiguration can be carried out at run time. Our system performs shape identification by the interpretation of their singularities. This is achieved by interconnecting several specialized TNN. The results of several tests, in different conditions are reported in the paper. The system detects accurately a test shape in almost all the experiments performed. The paper also contains a detailed description of the system architecture and the processing steps. In order to validate the research, the system has been implemented and was configured as a perceptron network with backpropagation learning and applied to the recognition of shapes. Simulation results show that this architecture has significant performance benefits

Wide bandgap semiconductor from a hidden 2D incommensurate graphene phase

Producing a usable semiconducting form of graphene has plagued the development of graphene electronics for nearly two decades. Now that new preparation methods have become available, graphene's intrinsic properties can be measured and the search for semiconducting graphene has begun to produce results. This is the case of the first graphene "buffer" layer grown on SiC(0001) presented in this work. We show, contrary to assumptions of the last forty years, that the buffer graphene layer is not commensurate with SiC. The new modulated structure we've found resolves a long standing contradiction where ab initio calculations expect a metallic buffer, while experimentally it is found to be a semiconductor. Model calculations using the new incommensurate structure show that the semiconducting $\pi$-band character of the buffer comes from partially hybridized graphene incommensurate boundaries surrounding unperturbed graphene islands.Comment: 17 pages, 4 figures, 1 table, 47 references, supplemental material: 15 pages, 4 figure

Can physical activity attenuate the negative association between sitting time and cognitive function among older adults? A mediation analysis

The purpose of this study was to examine the combined association of sitting time and physical activity with cognitive function and to determine whether moderate-to-vigorous physical activity (MVPA) is a mediator of the association between sitting time and cognitive function in a nationally representative sample of older adults from Chile. Data from 989 older adults (≥65 years old, 61.3% female) from the 2009-2010 Chilean Health Survey were analyzed. Physical activity and sitting time were measured using the Global Physical Activity questionnaire. Cognitive function was assessed using the modified Mini-Mental State levels Examination. Physical activity levels were categorized as "inactive" (<600 metabolic equivalent value minutes per week) or "active" (≥600 metabolic equivalent value minutes per week). Sitting time was categorized as "sedentary", defined as ≥4 h of reported sitting time per day, or "non-sedentary", defined as <4 h. We created the following groups (i) non-sedentary/active; (ii) non-sedentary/inactive; (iii) sedentary/active; and (iv) sedentary/inactive. Hayes's PROCESS macro was used for the simple mediation analysis. Compared with the reference group (individuals classified as non-sedentary/active), older adults who were classified as sedentary/active had elevated odds of cognitive impairment (OR = 1.90, [95% CI, 1.84 to 3.85]). However, the odds ratio for cognitive impairment was substantially increased in those classified as sedentary/inactive (OR = 4.85 [95% CI, 2.54 to 6.24]) compared with the reference group. MVPA was found to mediate the relationship between sitting time and cognitive function (Indirect Effect = -0.070 [95% CI, -0.012 to -0.004]). The present findings suggest that, whether overall physical activity is high or low, spending large amounts of time sitting is associated with elevated odds of cognitive impairment and that MVPA slightly weakens the relationship between sitting time and cognitive function