920 research outputs found
Efficient and Accurate hybrid GO-Spectral Algorithm to Design Conformal Serrated-Edge Reflectors Operating as Collimators in Millimeter Wave Compact Ranges
This paper presents a hybrid analysis algorithm, which is used at Radiation Group (UPM) to carry out the design of a conformal serrated-edge reflector for the mm-Wave compact range UPM facility. Main features of this algorithm involve its capability of handling conformal serrated rim parabolic reflectors, accuracy and computational efficiency
Antenna Measurement System at 300 GHz for the Terasense Project
The aim of this paper is to introduce the design techniques used to develop the antenna measurement system for the Terasense Project. This project, funded by the Spanish Government, involves millimetre-wave systems design. One of these systems is an antenna measurement facility. The antenna measurement system operates in a banded range of frequency. The lower frequencies deal between 75–110 GHz (WR10 operation range) and the upper frequencies are set between 220–325 GHz (WR03). Among the different possible configurations, the reflector-based compact range is chosen. The quiet zone is generated by a serrated-edge reflector, fed by a low gain horn. In this paper we will focus on the reflector design. A serrations study is carried out and quiet zone acquisition results are obtained
Contact forces distribution for a granular material from a Monte Carlo study on a single grain
The force network ensemble is one of the most promising statistical
descriptions of granular media, with an entropy accounting for all force
configurations at mechanical equilibrium consistent with some external stress.
It is possible to define a temperature-like parameter, the angoricity
{\alpha}^{-1}, which under isotropic compression is a scalar variable. This
ensemble is frequently studied on whole packings of grains; however, previous
works have shown that spatial correlations can be neglected in many cases,
opening the door to studies on a single grain. Our work develops a Monte Carlo
method to sample the force ensemble on a single grain at constant angoricity on
two and three-dimensional mono-disperse granular systems, both with or without
static friction. The results show that, despite the steric exclusions and the
constrictions of Coulomb's limit and repulsive normal forces, the pressure per
grain always show a gamma distribution with scale parameter {\nu} =
{\alpha}^{-1} and shape parameter k close to k', the number of degrees of
freedom in the system. Moreover, the average pressure per grain fulfills an
equipartition theorem =k'{\alpha}^{-1} in all cases (in close parallelism
with the one for an ideal gas). These results suggest the existence of k'
independent random variables (i.e. elementary forces) with identical
exponential distributions as the basic elements for describing the force
network ensemble at low angoricities under isotropic compression, in analogy
with the volume ensemble of granular materials
Simulation of a solar assisted counterflow tunnel dehydrator
A widely used class of vegetable dehydration systems are the “tunnel-and-truck” dehydrators, where the prepared material lies over horizontal trays stored in trucks which move discontinuously in opposite direction of the air flow. This way the driest product is facing the inlet hot and dry air blowed to the system. When product of one truck is ready, is removed from the tunnel leaving space for advance the remaining truck one place forward. This way, a new truck full of wet product can be inserted at the end of the tunnel. The hermal energy required for the process can be supplied by several sources including gas, biomass, solar energy or a combination of them. Solar energy is for free but reaches the
Earth with quite a low flux and a strongly fluctuating rate. This imposes the need of special designs and control strategies. This paper presents a study based on simulation models of the dehydrator and the solar thermal system. The dehydrator simulation model is tuned to match experimental data from a particular prototype based on fossil fuel. A solar system simulation model is then applied to the analysis of different design options.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
Suppression of the intrinsic stochastic pinning of domain walls in magnetic nanostripes
Nanofabrication has allowed the development of new concepts such as magnetic logic and race-track memory, both of which are based on the displacement of magnetic domain walls on magnetic nanostripes. One of the issues that has to be solved before devices can meet the market demands is the stochastic behaviour of the domain wall movement in magnetic nanostripes. Here we show that the stochastic nature of the domain wall motion in permalloy nanostripes can be suppressed at very low fields (0.6-2.7 Oe). We also find different field regimes for this stochastic motion that match well with the domain wall propagation modes. The highest pinning probability is found around the precessional mode and, interestingly, it does not depend on the external field in this regime. These results constitute an experimental evidence of the intrinsic nature of the stochastic pinning of domain walls in soft magnetic nanostripe
Modeling and sizing of large PV-diesel hybrid systems without energy storage
This paper describes the modelling of components and control strategies for PV-diesel hybrid systems without energy storage, which have been implemented in an online and free-software simulator of PV systems called SISIFO, which is publicly available at www.sisifo.info. Among other features, this software tool allows the prediction of fuel savings for different sizes and types of PV generators, the comparison of selected control strategies and the evaluation of the spinning reserve requirements in systems with multiple diesel generators operating in parallel
Transfer learning or design a custom CNN for tactile object recognition
International Workshop on Robotac: New Progress in Tactile Perception and Learning in RoboticsNovel tactile sensors allow treating pressure lectures as standard images due to its highresolution. Therefore, computer vision algorithms such as Convolutional Neural Networks
(CNNs) can be used to identify objects in contact. In this work, a high-resolution tactile
sensor has been attached to a robotic end-effector to identify objects in contact. Moreover,
two CNNs-based approaches have been tested in an experiment of classification of pressure
images. These methods include a transfer learning approach using a pre-trained CNN on an
RGB images dataset and a custom-made CNN trained from scratch with tactile information.
A comparative study of performance between them has been carried out.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech. Spanish project DPI2015-65186-R, the European Commission under grant agreement BES-2016-078237, the educational project PIE-118 of the
University of Malag
Structural and numerical identifiability of thermal resistances in plate fin-and-tube heat exchangers using manufacturer catalog data
Plate fin-and-tube heat exchangers, commonly known as heating/cooling coils, are widely used in HVAC systems to transfer heat to or from air. A problem of practical interest in coil simulation is to identify the thermal resistances on the air and liquid sides using manufacturer catalog data. Manufacturers rarely provide detailed information (geometry and circuitry) of the coils they sell or install in factory-made equipment such as air handling units or fan-coils; they just report the performance of the coil at a few typical operating conditions. This paper examines whether it is mathematically possible to back-calculate the thermal resistances on the air and liquid sides using a set of performance data that is disturbed by noise (e.g. measurement errors) and consists of operating cases in which none of the two thermal resistances can be neglected. The first part of the paper discusses the structural identifiability problem, that is, the mathematical possibility of fitting Nusselt-type correlations for air and liquid, as well as a constant resistance for the wall. The second part of the paper discusses the possibility of calculating the numerical value of the parameters of the Nusselt correlations (constant or constant and exponent) using noisy data. The analysis is applied to a typical coil, which is simulated by means of a mathematical modelUniversidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
Experiencia docente en Automática empleando un robot mĂłvil como elemento motivador de metodologĂas activas
A. J. Muñoz-RamĂrez and J. M. Gomez-de-Gabriel, “Experiencia docente en Automática empleando un robot mĂłvil como elemento motivador de metodologĂas activas.pdf,” in Indotec V- 5o International Conference on Educational Innovation in Technical Careers, 2017, pp. 77–82.)Los nuevos tĂtulos de grado centrados en la adquisiciĂłn de competencias, obligan a adaptar la docencia de las
asignaturas hacia un nuevo modelo, donde las competencias son el nĂşcleo de aprendizaje. La tecnologĂa actual
ofrece herramientas tales como los entornos de trabajo centrados en el docente como el campus virtual, con
Moodle como implementación más extendida, o centrados en el aprendizaje del estudiante como el portafolio
electrónico, con “Mahara” una de las implementaciones de mayor difusión; la grabación y producción de
vĂdeos, presentaciones digitales, etc; cuyo dominio garantiza la adquisiciĂłn de competencias en TIC. Por otra
parte, el empleo de metodologĂas activas centradas en el aprendizaje consigue alcanzar varias competencias de
las consideradas claves tanto para el aprendizaje permanente (DO UE L 394 de 30.12.2006) como para su
empleo en la futura vida profesional (DE JUANAS OLIVA, 2010). De ambas destacan en comĂşn las
competencias centradas en el aprender a aprender que además es señalada por los estudiantes en como la más
valorada por los estudiantes universitarios(ANECA, 2007).Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
Modelar o programar en prácticas de robótica
En este trabajo se muestra la experiencia de usar una herramienta de desarrollo de ingenierĂa basada en modelos (MDE) frente a otra herramienta tradicional de programacion de sistemas embebidos en lenguaje C, para la realizacion de clases practicas de robotica. Se ha plantea do una practica basada en el control cinemático de un robot mĂłvil en ambos entornos con similares bloques y funciones de partida. Los resultados muestran tanto la comparaciĂłn de las evaluaciones objetivas realiza das a los dos grupos como los datos relativos a los tiempos requeridos para la realizaciĂłn de las diferentes partes de la practica. Si bien, los resultados del aprendizaje son mayores en el caso del mĂ©todo basado en programacion, la diferencia en tiempos invertidos y otras valoraciones hacen m´as adecuado el MDE .Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
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