Minimization of measuring points for the electric field exposure map generation in indoor environments by means of Kriging interpolation and selective sampling

In a world with increasing systems accessing to radio spectrum, the concern for exposure to electromagnetic fields is growing and therefore it is necessary to check limits in those areas where electromagnetic sources are working. Therefore, radio and exposure maps are continuously being generated, mainly in outdoor areas, by using many interpolation techniques. In this work, Surfer software and Kriging interpolation have been used for the first time to generate an indoor exposure map. A regular measuring mesh has been generated. Elimination of Less Significant Points (ELSP) and Geometrical Elimination of Neighbors (GEN) strategies to reduce the measuring points have been presented and evaluated. Both strategies have been compared to the map generated with all the measurements by calculating the root mean square and mean absolute errors. Results indicate that ELSP method can reduce up to 70% of the mesh measuring points while producing similar exposure maps to the one generated with all the measuring points. GEN, however, produces distorted maps and much higher error indicators even for 50% of eliminated measuring points. As a conclusion, a procedure for reducing the measuring points to generate radio and exposure maps is proposed based on the ELSP method and the Kriging interpolation.This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors

Tutoría grupal para la resolución de problemas de síntesis de amplificadores sintonizados y análisis de mezcladores en ingeniería de telecomunicación

[SPA]En esta comunicación se explica la metodología de trabajo seguida en la ETSI de Telecomunicación de la Universidad Politécnica de Cartagena para el desarrollo de competencias de trabajo en grupo a través de la realización de tutorías grupales. Los alumnos elegidos para llevar a cabo estas actividades son los matriculados en la asiguatura optativa de Subsistemas de Radiofrecuencia, perteneciente a cuarto curso de la titulación de Ingeniero de Telecomunicación. La tuturía grupal se ha centrado en la resolución de problemas tipo de diseño de amplificadores sintonizados de radiofrecuencia así como el análisis de mezcladores. La propia evaluación del proceso por parte de los alumnos y los profesores muestran que los alumnos se sienten satisfechos en este tipo de actividades debido a la agilidad en la identificación de dudas y su resolución. Sin embargo, en los casos de alumnos sobresalientes el proceso puede ser un poco frustrante debido a su alto dominio previo de la asignatura. [ENG]In this communication, the methodology followed by teachers and students of the ETSI de Telecomunicación within Universidad Politécnica de Cartagena for the development of group cooperation competencies by means of group tutorials is explained. The chosen students for carrying out this activities belong to Radiofrequency Subsystems subject within the fourth academic year of Telecommunication Engineer Degree. Group Tutorial sessions have focused on 1474 typical RF tuned amplifiers design and mixer analysis problems. Students and teachers evaluation of the process shows that students are satisfied withi this kind of activities since doubts were quickly identified and solved. However, for outstanding students the process can be a bit frustrating due to their higher previous command of the subject.Campus Mare Nostrum, Universidad Politécnica de Cartagena, Universidad de Murcia, Región de Murci

Benefits of using conductive plastics in shielding configurations to reduce radiated electromagnetic interference

Conductive plastic cabinets have become an alternative to traditional metallic enclosures to shield electronic equipment from electromagnetic interference. These materials allow a wide range of conductivities that can satisfy any particular design. In this paper the benefits of using conductive plastics in enclosure configurations have been evaluated. A design with an outer metallic layer and an inner layer of conductive dielectric can provide advantages from both materials since a conductive plastic box is lighter and its shielding properties may have advantages over metallic materials. An optimum for resonance suppression has been obtained for the hybrid structure. These shielding structures have been evaluated with the help of measurements and simulations. Shielding effectiveness and Q-factor have been used to compare the capabilities of these enclosures with the metallic ones showing their benefits and possibilities. Resonance suppression and shielding levels provided by conductive plastics are discussed.This work was funded by Fundación Séneca, Agencia Regional de Ciencia y Tecnología, through the project 00700/PPC/04 and partly done during a research stay funded by the “Programa de formación y movilidad del personal docente e investigador de la Universidad Politécnica de Cartagena (PMPDI-UPCT-2007)” at the Physical Layer Group, Department of Electronics, University of York

A novel design of a robust ten-port microwave reflectometer with autonomous calibration by using neural networks

In this study, a novel ten-port waveguide microwave sensor is designed, implemented, calibrated and tested in order to obtain the reflection coefficient magnitude and phase. This reflectometer is based on the well known six-port structure but the number of detectors has been increased to eight in order to improve the sampling procedure of the standing wave present within the waveguide. In addition, a learning method based on neural networks’ usage has been implemented for autonomous calibration from the data collected by a vector network analyzer. An automated procedure consisting of a moving sample within a multimode cavity has enabled different reflection coefficients to be obtained. Neural networks have been employed in order to learn the relationship between the actual reflection parameter and the acquired signals from eight power detectors. This novel device has been calibrated with a neural architecture based on radial basis functions and the error of device measurements has been analyzed. This new design and the incorporated neural network calibration allow one to avoid problems caused by fault or nonlinearity of the detectors, and to get robustness, flexibility and adaptability characteristics for the presented device

Patrón primario de ruido térmico de banda ancha

Número de publicación: 2 415 083 Número de solicitud: 201130156Patrón primario de ruido térmico de banda ancha. Sistema coaxial para un patrón primario empleado en la trazabilidad de fuentes de ruido térmico, que comprende una línea de transmisión coaxial y un anillo, estando una parte de la línea de transmisión coaxial sumergida en nitrógeno líquido y otra parte de la línea de transmisión coaxial rodeada por un circuito de agua donde se encuentra el anillo, comprendiendo la citada línea de transmisión coaxial un conductor exterior y un conductor interior, estando ambos conductores unidos mediante el anillo que está realizado en un material que garantiza la conductividad térmica entre el conductor exterior y el conductor interior, comprendiendo el anillo un tramo central en contacto en toda su longitud con la superficie interior del conductor exterior, y porque la relación entre el radio del conductor interior y el radio exterior del anillo es tal que en toda la longitud del anillo la impedancia es la misma que la impedancia nominal de la línea coaxial.Universidad Politécnica de CartagenaInstituto Nacional de Técnica Aeroespacial (INTA

A novel technique for sterilization using a power self-regulated single-mode microwave cavity

In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs) for different food samples (laboratory medium, soup, or fish-based animal by-products). The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures.This work was supported by the Ministerio de Economía y Competitividad under the project with reference DPI2014-61857-EXP

Fast computation of shielding effectiveness of metallic enclosures with apertures and inner elements

In this study, radiated immunity and emission of a metallic box with apertures have been evaluated through a fast approach. The influence of printed circuit boards inside the enclosure has been studied and also the effect of placing conductive polymer sheets in the housing in order to characterize the behaviour of these materials used nowadays for shielding cabinets. Measurements have been carried out in anechoic chamber in order to evaluate the approximated technique showing its limitations and advantages. Since good agreement has been found between simulations and measurements, this approach can be used for design or optimization purposes with the main advantage of reduced time calculations.This work has been funded by Fundación Séneca, Agencia Regional de Ciencia y Tecnología through the project 00700/PPC/04

Noble gas variation during partial crustal melting and magma ascent processes

Noble gas isotopes, although present in trace amounts, are generally more reliable and less ambiguous recorders of their source than the major volatile species. In volcanic settings in particular, this advantage derives from their chemical inertness, as noble gas isotopic and elemental fractionations are strongly coupled to their source and modified only by physical processes during magma ascent and eruption. The Neogene volcano El Hoyazo (Betic Cordillera, SE Spain) is a highly favourable natural laboratory to study the links between partial crustal melting processes occurring at depth and the eruptive products at the surface, because partially melted crustal xenoliths are preserved in silicic lavas. Comparing the noble gas isotopic compositions of xenoliths and lavas has the potential to yield new insights into volatile behaviour during melting processes at inaccessible depths in the crust. At El Hoyazo, noble gases trapped in lava glasses, and the fluid/melt inclusions within xeno- and phenocrysts, provide novel information on: (i) their response to the crustal melting process including mechanisms such as magma mixing (and crustal assimilation) of two endmembers: i.e. the extracted felsic melt from the country metapelitic crust, and the basic-intermediate magma from the underplating in the region. The results reveal significant modification of magmatic noble gases by the interaction with the partially melted crust; (ii) noble gas variations during degassing and magma ascent, showing higher atmospheric influence in the lava samples from shallower depths than in the deeper lavas and minerals; and (iii) higher magmatic influence in crystals of garnet from deeper lava than in both shallower crystals of amphibole, and garnet crystals within the crustal xenoliths. In addition, we find that noble gases in melt inclusions are also likely accumulating in their shrinkage bubbles, and not only remaining dissolved in the melt.Postprint3,51

Aplicación de algoritmos genéticos en el diseño de hornos microondas: eficiencia energética y calentamiento uniforme

En este artículo se describe la aplicación de algoritmos genéticos en el diseño de hornos microondas para procesos industriales de calentamiento. Los objetivos perseguidos en estos diseños son, fundamentalmente, la eficiencia energética mediante una adecuada adaptación entre la fuente de microondas y su carga, y la obtención de un campo eléctrico sobre la muestra lo más uniforme posible, con el fin de generar un calentamiento homogéneo en todo el producto y aumentando así la calidad del producto fina

A new sensor-based self-configurable bandstop filter for reducing the energy leakage in industrial microwave ovens

In this work a new sensor-based self-configurable waveguide bandstop filter that uses a combination of metallic irises and reconfigurable posts for reducing the energy leakage in industrial microwave ovens is presented and validated through a procedure fully based on measurements. Several optimization and reconfiguration alternatives of the moving posts such as genetic algorithms and parametric sweeps are assessed. Results show that good attenuation values can be obtained for all the analyzed scenarios. In particular, genetic algorithms are shown as the best search strategy. Design and optimization times are also reduced when using the proposed filter compared to computer simulations