Enhancement of Millimeter-Band Transceivers with Gap Waveguide Technology

Mención Internacional en el título de doctorIt is known to all that year after year in modern society there is an urgent demand to consume wirelessly, and even stream ever larger multimedia content. High-frequency technologies have made it possible to go from transmitting analog voice and SMS text messages, to now transmitting live video in 4K quality from a mid-range smartphone. The way to measure these advances is by the bandwidth (Mb/s) reserved for each network user and the cost required to achieve it. To achieve even higher bandwidths, it is essential to improve signal coding techniques or increase the frequency of the signal, for example: to the mmWave bands (25GHz - 100 GHz), where these high-frequency techniques come into play. However, there is a frequency limit where current planar technology materials - such as the printed circuit boards used to build RF devices - are so lossy that they are not suitable at these mmWave frequencies. Current commercial solutions consist of guiding the electromagnetic energy with hollow metallic waveguides, but they suffer from the problem that as the frequency increases the diameter of these waveguides gets smaller and smaller, so manufacturing tolerances increase exorbitantly. Not to mention that they are usually manufactured in two parts, one upper and one lower, whose joints are not always perfect and produce energy losses. With these issues in mind, in 2009 the theory and basic science of a new electromagnetic energy guidance technology called Gap Waveguide was proposed, which is based on the use of metasurfaces constructed with periodic elements similar to a bed of nails. There are several implementations of this technology, but the three main ones are: Ridge, Groove and Inverted Microstrip Gap Waveguide. The latter is the most compatible with conventional planar manufacturing technologies and therefore the most cost-effective, although it also has drawbacks mainly in terms of losses when compared to the other versions. This thesis aims to deepen the study of the Inverted Microstrip guidance technology, its limitations and to develop with it some of the needed components in RF systems such as filters, diplexers, amplifiers, antennas, etc. Regarding the methodology for this thesis, a commercial simulation software for the analysis of antennas and components, CST Microwave Studio [1], has been used. AWR Microwave Office [2], a circuit simulator, has also been used to complement the simulations. On the other hand, there is a laboratory for the manufacture of prototypes in printed technology (with some limitations in terms of resolution) and the corresponding measurement laboratory, which includes network analyzers up to 40 GHz, spectrum analyzers and an anechoic chamber.This thesis arose under the Spanish Ministry of Science and Innovation (MINECO) and European Regional Development Fund (ERDF) project, called "Antenna for Mobile Satellite Communications (SATCOM) in Ka-Band by means of metasurfaces (2016-2019)", with reference TEC2016-79700-C2-2-R. Under this contract, the author signed an FPI research contract.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Íñigo Cuiñas Gómez.- Secretario: Ángela María Coves Soler.- Vocal: Astrid Algaba Brazále

Diplexor y antena en tecnología Microstrip Gap Waveguide

Un diplexor es un dispositivo que permite que dos sistemas separados compartan la misma antena. Un diplexor consiste en dos filtros separados que adaptan los requisitos de la banda de paso y el ancho de banda a cada sistema conectado. En comunicaciones por satélite, por ejemplo, los diplexores de transmisión‐recepción forman parte del transpondedor de la carga útil y se emplean para aislar adecuadamente las señales del enlace de subida y del enlace de bajada, que comparten la misma antena. En este sentido, este dispositivo debe tener bajas pérdidas de inserción para permitir la recepción de la señal de subida a la vez que maximiza la potencia transmitida en la señal de bajada. A su vez, debe ser lo suficientemente selectivo para que la interferencia producida por la potente señal de bajada no interfiera en la débil señal de subida. Por tanto, en este tipo de aplicaciones el parámetro de diseño más importante son las pérdidas de inserción de los filtros, sin embargo, también se exige que cumplan fuertes restricciones de selectividad y planitud en la banda.  Un diplexor es un dispositivo que permite que dos sistemas separados compartan la misma antena. Un diplexor consiste en dos filtros separados que adaptan los requisitos de la banda de paso y el ancho de banda a cada sistema conectado. En comunicaciones por satélite, por ejemplo, los diplexores de transmisión‐recepción forman parte del transpondedor de la carga útil y se emplean para aislar adecuadamente las señales del enlace de subida y del enlace de bajada, que comparten la misma antena. En este sentido, este dispositivo debe tener bajas pérdidas de inserción para permitir la recepción de la señal de subida a la vez que maximiza la potencia transmitida en la señal de bajada. A su vez, debe ser lo suficientemente selectivo para que la interferencia producida por la potente señal de bajada no interfiera en la débil señal de subida. Por tanto, en este tipo de aplicaciones el parámetro de diseño más importante son las pérdidas de inserción de los filtros, sin embargo, también se exige que cumplan fuertes restricciones de selectividad y planitud en la banda.  Así mismo, la tecnología GAP Waveguide (GWG) es una nueva tecnología de circuitos de microondas que tiene importantes ventajas en la banda de frecuencias de 30 GHz hasta frecuencias de THz.  Las guías GWG tienen menos pérdidas que las líneas microstrip de uso común y que las guías de ondas coplanares basadas en tiras de metal sobre un sustrato dieléctrico.  También tienen menores pérdidas que las llamadas guías de onda con sustrato integrado (Substrate Integrated Waveguides o SIW). Las guías GWG tienen pérdidas similares a las comunes guías de onda rectangulares todo‐metálicas, pero son más rentables en la producción, ya que se pueden hacer sin realizar uniones entre las piezas de metal. Las guías GWG también se pueden utilizar para eliminar problemas de resonancia que aparecen al encapsular circuitos pasivos y activos basados en tecnología microstrip y de guías coplanares. Las prestaciones superiores de la tecnología de las guías GWG, tanto como línea de transmisión para la fabricación de circuitos de microondas, como tecnología de encapsulado, se han verificado y descrito en varios artículos de revistas científicas, y en congresos. El proyecto consiste en realizar una antena y un diplexor con los dos filtros (de transmisión y recepción) en tecnología microstrip GWG, con la construcción y medida del prototipo.A diplexer is a device that allows two separate systems to share a single antenna. A diplexer consists of two separate filters that match the bandpass and bandwidth requirements of each connected system. In satellite communications, for example, diplexers transmit‐receive part of the transponder payload and used to properly isolate signals uplink and downlink, which share the same antenna.  In this sense, this device must have low insertion loss to allow the reception of the signal rise while maximizing the transmitted signal power down. At the same time, must be selective enough to interference from the downlink signal strength does not interfere with the weak signal rise. Therefore, in such applications the most important design parameter is the insertion loss of the filters, however, also be required to meet the selectivity and strong constraints on the band flatness. The GAP waveguide technology (GWG) is a new microwave circuit technology that has major advantages for use in the frequency band from 30 GHz to Terahertz frequencies. The GAP waveguides have smaller losses than commonly used microstrip lines and coplanar waveguide, based on metal strips on a dielectric substrate. They have also lower losses than so‐called substrate integrated waveguides (SIW). The GAP waveguides have similar losses as commonly‐used entire‐metal rectangular waveguides, but are on the other hand more cost‐effective in production because they can be made without conducting joints between metal parts. The GAP waveguides can also be used for eliminating resonance problems appearing when packaging passive and active circuits based on microstrip and coplanar waveguides. The superior performances of the GAP waveguide technology both as a transmission line for making advanced microwave circuits and as a packaging technology, have already been verified and described in several scientific journal articles, letter and conference papers. The goal of this project is using Microstrip Gap Waveguide technology to design filters, power divider and antenna for diplexer. These are manufactured later in printed circuited board thanks to the Microstrip GWG technology with low cost, weight and size. Ingeniería Técnica en Sistemas de Telecomunicació

Trastorno de la personalidad: un desafío en la relación médico-paciente

ResumenEl paciente con trastorno de la personalidad límite o con trastornos afectivos suele obstaculizar la relación médico-paciente debido a sus conflictos emocionales. Es importante que el médico familiar reconozca de manera oportuna dichos trastornos y desarrolle habilidades tanto para la comunicación como para la empatía; con el propósito de favorecer una adecuada relación médico-paciente y referir oportunamente al enfermo a un servicio de atención especializado. De este modo se podrán prevenir la cronicidad, la iatrogenia y la estigmatización del paciente, así como la frustración e impotencia del equipo médico.SummaryPatients with limit personality disorder or affective disorders often hinder the doctor-patient relationship due to their emotional conflicts. It is important that the Family Physician recognized in a timely manner such disorders and develop skills for communication and empathy; in order to promote a proper doctor-patient relationship and promptly refer the patient to a specialist. Thus this will prevent chronicity, iatrogenic and stigmatization of the patient, as well as frustration and a sense of helplessness of the medical team

Experimental assessment of different extraction points for the integrated mechanical subcooling system of a CO2 transcritical plant

Subcooling systems are positioned in recent years as one of the best solutions to improve the efficiency of transcritical CO2 cycles. Specifically, the integrated mechanical subcooling cycle allows the improvement of these systems only using CO2 as a refrigerant. This integrated cycle can be designed with three different architectures: extracting the CO2 from the gas-cooler outlet, from the subcooler outlet or from the liquid tank. In this work, the three configurations are experimentally analysed and the main differences between them are studied. An experimental plant has been tested at three heat rejection levels (25.0, 30.4 and 35.1°C) and a fixed temperature of the secondary fluid at the evaporator inlet of 3.8°C. The results show that from an energy efficiency point of view, all the configurations have practically the same COP, with certain variations in the cooling capacity and the greatest differences in the cycles are found in the subcooler.Funding for open access charge: CRUE-Universitat Jaume

Effects caused by the internal heat exchanger at the low temperature cycle in a cascade refrigeration plant

This work analyses and quantifies the effects caused by the use of an internal heat exchanger (IHX) at the CO2 subcritical cycle in an HFC134a/CO2 cascade refrigeration plant that incorporates a gas-cooler at the exit of the low temperature compressor. Previous theoretical and experimental studies showed that the IHX reduces the refrigeration capacity and COP of the subcritical cycle, however, it has been seen that it also lowers the heat to be rejected at the condenser. This reduction, when the cycle is a part of a cascade system, allows reducing the heat load of the high temperature cycle, modifying the working conditions of the cascade plant. The modifications result in an increment of the overall coefficient of performance of the cascade system. The analysis here presented is based on the evaluation of an experimental HFC134a/CO2 refrigeration plant, which has been analysed with and without internal heat exchanger in an evaporating temperature range from -40 to -30 ºC and in a condensing one from 30 to 50 ºC. The plant incorporates a gas-cooler at the exit of the CO2 compressor. The experimental results confirm that the IHX slightly reduces the cooling capacity but it can increment the overall COP up to 3.7 %.The authors gratefully acknowledge the Ministerio de Economía y Competitividad – Spain (project ENE2014-53760-R.7) and the Jaume I University – Spain (project P11B2015-66) for financing this research work

Synthetic RGB photometry of bright stars: definition of the standard photometric system and UCM library of spectrophotometric spectra

Although the use of RGB photometry has exploded in the last decades due to the advent of high-quality and inexpensive digital cameras equipped with Bayer-like color filter systems, there is surprisingly no catalogue of bright stars that can be used for calibration purposes. Since due to their excessive brightness, accurate enough spectrophotometric measurements of bright stars typically cannot be performed with modern large telescopes, we have employed historical 13-color medium-narrow-band photometric data, gathered with quite reliable photomultipliers, to fit the spectrum of 1346 bright stars using stellar atmosphere models. This not only constitutes a useful compilation of bright spectrophotometric standards well spread in the celestial sphere, the UCM library of spectrophotometric spectra, but allows the generation of a catalogue of reference RGB magnitudes, with typical random uncertainties $\sim 0.01$ mag. For that purpose, we have defined a new set of spectral sensitivity curves, computed as the median of 28 sets of empirical sensitivity curves from the literature, that can be used to establish a standard RGB photometric system. Conversions between RGB magnitudes computed with any of these sets of empirical RGB curves and those determined with the new standard photometric system are provided. Even though particular RGB measurements from single cameras are not expected to provide extremely accurate photometric data, the repeatability and multiplicity of observations will allow access to a large amount of exploitable data in many astronomical fields, such as the detailed monitoring of light pollution and its impact on the night sky brightness, or the study of meteors, solar system bodies, variable stars, and transient objects. In addition, the RGB magnitudes presented here make the sky an accessible and free laboratory for the calibration of the cameras themselves.Comment: 19 pages, 18 figures, 7 tables. Accepted for publication in MNRA

Statistical modeling approach for PM10 prediction before and during confinement by COVID-19 in South Lima, Perú

A total of 188,859 meteorological-PM10 data validated before (2019) and during the COVID-19 pandemic (2020) were used. In order to predict PM10 in two districts of South Lima in Peru, hourly, daily, monthly and seasonal variations of the data were analyzed. Principal Component Analysis (PCA) and linear/nonlinear modeling were applied. The results showed the highest annual average PM10 for San Juan de Mirafores (SJM) (PM10-SJM: 78.7 µg/m3) and the lowest in Santiago de Surco (SS) (PM10 -SS: 40.2 µg/m3). The PCA showed the infuence of relative humidity (RH)-atmospheric pressure (AP)temperature (T)/dew point (DP)-wind speed (WS)-wind direction (WD) combinations. Cool months with higher humidity and atmospheric instability decreased PM10 values in SJM and warm months increased it, favored by thermal inversion (TI). Dust resuspension, vehicular transport and stationary sources contributed more PM10 at peak times in the morning and evening. The Multiple linear regression (MLR) showed the best correlation (r = 0.6166), followed by the three-dimensional model LogAP-LogWD-LogPM10 (r = 0.5753); the RMSE-MLR (12.92) exceeded that found in the 3D models (RMSE < 0.3) and the NSE-MLR criterion (0.3804) was acceptable. PM10 prediction was modeled using the algorithmic approach in any scenario to optimize urban management decisions in times of pandemic.Campus San Juan de Luriganch

Development of tailored and self-mineralizing citric acid-crosslinked hydrogels for in situ bone regeneration

Producción CientíficaBone tissue engineering demands alternatives overcoming the limitations of traditional approaches in the context of a constantly aging global population. In the present study, elastin-like recombinamers hydrogels were produced by means of carbodiimide-catalyzed crosslinking with citric acid, a molecule suggested to be essential for bone nanostructure. By systematically studying the effect of the relative abundance of reactive species on gelation and hydrogel properties such as functional groups content, degradation and structure, we were able to understand and to control the crosslinking reaction to achieve hydrogels mimicking the fibrillary nature of the extracellular matrix. By studying the effect of polymer concentration on scaffold mechanical properties, we were able to produce hydrogels with a stiffness value of 36.13 ± 10.72 kPa, previously suggested to be osteoinductive. Microstructured and mechanically-tailored hydrogels supported the growth of human mesenchymal stem cells and led to higher osteopontin expression in comparison to their non-tailored counterparts. Additionally, tailored hydrogels were able to rapidly self-mineralize in biomimetic conditions, evidencing that citric acid was successfully used both as a crosslinker and a bioactive molecule providing polymers with calcium phosphate nucleation capacity.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA244U13

Experimental evaluation of an internal heat exchanger in a CO2 subcritical refrigeration cycle with gas-cooler

We present the experimental evaluation of an internal heat exchanger or suction-line/liquid-line heat exchanger in a CO2 subcritical refrigeration plant with gas-cooler. The plant, driven by a 1.5 kW CO2 semi hermetic compressor, uses brazed plate heat exchangers as condenser, evaporator and internal heat exchanger, an air finned tube gas-cooler and an electronic expansion valves. The evaluation (77 steadystates) covers evaporating temperatures from 40 to 25 C and condensing temperatures from 15 to 0 C, always at the nominal speed of the compressor. Here, the effect of the internal heat exchanger on the main energy parameters is analysed, i.e., cooling capacity, COP and heat rejection at gas-cooler and condenser. Also, the effect of the internal heat exchanger in a cascade cycle is analysed theoretically. It has been concluded that the internal heat exchanger does not improve the performance of the subcritical cycle, but it could improve the energy performance if it is used inside a cascade refrigeration system.The authors gratefully acknowledge Jaume I University of Spain, who financed the present study through the research project P1.B2013-10.Llopis Doménech, R.; Sanz Kock, C.; Cabello, R.; Sanchez, D.; Torrella Alcaraz, E. (2015). Experimental evaluation of an internal heat exchanger in a CO2 subcritical refrigeration cycle with gas-cooler. Applied Thermal Engineering. 80:31-41. https://doi.org/10.1016/j.applthermaleng.2015.01.040S31418

Observaciones sobre el estudio experimental de una instalación de refrigeración en cascada con CO2 como fluido de baja temperatura

En este trabajo se presentan las primeras conclusiones obtenidas sobre los análisis experimentales realizados en una instalación de producción de frío en doble compresión indirecta (cascada) que utiliza el CO2 como fluido de baja temperatura. En primer lugar se describirá el banco de ensayos construido, formado por el equipamiento frigorífico, los elementos de medida y sistema de adquisición de datos desarrollado. A continuación se describirá el procedimiento de validación de los datos y cálculo de incertidumbres de los principales parámetros energéticos. Finalmente, se presentarán las principales conclusiones obtenidas del análisis experimental trabajando con R134a como fluido de alta temperatura: la evolución y comparaciones de los rendimientos de los compresores, los principales parámetros de operación y la forma de regulación utilizada, el efecto del intercambiador intermedio en el ciclo de CO2 y el efecto del gas-cooler en el ciclo de CO2.Los autores agradecen a la Universitat Jaume I de España, quien ha financiado parcialmente el presente estudio con el proyecto de investigación P1·B2013-10, y al Ministerio de Economía y Competitividad con el proyecto de investigación ENE2014-53760-R