Dpto. Ingeniería Eléctrica, Electrónica y de Comunicación - Ingeniaritza Elektriko eta Elektronikoaren eta Komunikazio Ingeniaritzaren Saila [desde mayo 2018 / 2018ko maiatzetik]

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Open Access
0.6-V CMOS bulk-driven instrumentation amplifier for IoMT bioimpedance analysis
(Wiley, 2024) Carrillo, Juan M.; Ocampo-Hidalgo, Juan J.; Corbacho, Israel; Cruz Blas, Carlos Aristóteles de la; Domínguez, Miguel Á.; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
An instrumentation amplifier (IA), aimed at wideband bioimpedance analysisin the low-voltage low-power scenario of internet of medical things (IoMT), ispresented. The operation principle is based on the indirect current feedbacktechnique, where an input and a feedback transconductor determine thevoltage gain of the preamplifier. The required transconductors consist of twobulk-driven flipped-voltage-follower cells and an active pseudo-resistor, thusleading to a linear and compact implementation. The circuit has been designedand fabricated in 180 nm CMOS technology to operate with a 0.6-V supply.Experimental results obtained from measurements on eight samples of thesilicon prototype show that when the IA is programmed to have a nominalvoltage gain of 11 V/V, the bandwidth is 316.2 kHz, the CMRR exceeds63 dB, and the maximum output voltage that can be processed with a THDbelow –40 dB is 555 mVpp.
Open Access
An acceleration approach for channel deterministic approaches based on quasi-stationary regions in V2X communications
(IEEE, 2024) Rodríguez Corbo, Fidel Alejandro; Celaya Echarri, Mikel; Shubair, Raed M.; Falcone Lanas, Francisco; Azpilicueta Fernández de las Heras, Leyre; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
Vehicular environments are characterized by a high mobility, which alongside with the presence of abundant dynamic scatterers, lead to vehicular communication channels to be intrinsically non-stationary. In this sense, the quasi-stationary regions (QSRs) can assess the degree of non-stationarity within a determined scenario, and ultimately assist geometrical models to increase channel sampling intervals or to develop more efficient hybrid stochastic-geometric channel models. In this work, the channel QSRs in a vehicular communication (V2X) generic highdense urban environment at millimeter wave (mmWave) frequencies (28 GHz) have been analyzed using different approaches, such as the extended channel response into a Doppler-delay domain or the shadow fading spatial auto-correlation function (SF ACF) methodology. Then, the QSRs have been used as sampling distance in an in-house developed three-dimensional ray-launching (3D-RL) algorithm as an acceleration approach. The time variant channel features have been extracted and compared with the full resolution approach, obtaining consistent results when considering the QSR sampling distances, while decreasing by 83.30% the simulation computational time for the Doppler-delay approach, and 92.86% for the SF ACF method.
Open Access
Advances in sensors using lossy mode resonances
(SPIE, 2023-11-27) Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Lossy mode resonance (LMR) is a phenomenon that is observed in the optical spectrum when a mode that progresses through a waveguide starts to be guided in a thin film deposited on this waveguide under certain conditions, mainly related to materials and angles of incidence. An important property that LMRs have is that they can be guided into the thin film with both magnetic (TM) and electrical (TE) polarized light, unlike the other two main types of optical resonances with the same modus operandi that complete this trilogy, surface plasmon resonances (SPRs) and surface exciton plasmon resonances (SEPR). Regarding the potential materials that make up thin films, they include dielectrics suchs as metal oxides such as titanium dioxide (TiO2), zinc oxide (ZnO), tin oxide (SnO2) or polymers. In all cases it must be fulfilled that the real part of the refractive index must be greater than its imaginary part, unlike also the SPR and SEPR. As for the angles of incidence, they must be close to 90º, which explains the success of deposition of thin films around an optical fiber to obtain sensors based on LMR, although interesting results have recently been obtained using planar waveguides. This work will present the main milestones obtained during more than a decade using LMR-based sensors for the detection of multiple parameters. Among these interesting aspects, we can mention the sensitivity records achieved, hybridization with other sensing technologies or the possibility of multiplexing multiple sensors on the same substrate, just to mention a few.
Open Access
Advancing ASL kidney image registration: a tailored pipeline with VoxelMorph
(Springer, 2025-01-31) Oyarzun Domeño, Anne; Cia Alonso, Izaskun; Echeverría Chasco, Rebeca; Fernández Seara, María A.; Martín Moreno, Paloma L.; García Fernández, Nuria; Bastarrika, Gorka; Navallas Irujo, Javier; Villanueva Larre, Arantxa; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
In clinical renal assessment, image registration plays a pivotal role, as patient movement during data acquisition can significantly impede image post-processing and the accurate estimation of hemodynamic parameters. This study introduces a deep learning-based image registration framework specifically for arterial spin labeling (ASL) imaging. ASL is a magnetic resonance imaging technique that modifies the longitudinal magnetization of blood perfusing the kidney using a series of radiofrequency pulses combined with slice-selective gradients. After tagging the arterial blood, label images are captured following a delay, allowing the tagged blood bolus to enter the renal tissue, while control images are acquired without tagging the arterial spins. Given that perfusion maps are generated at the pixel level by subtracting control images from label images and considering the relatively small signal intensity difference, precise alignment of these images is crucial to minimize motion artefacts and prevent significant errors in perfusion calculations. Moreover, due to the extended ASL acquisition times and the anatomical location of the kidneys, renal images are often susceptible to pulsation, peristalsis, and breathing motion. These motion-induced noises and other instabilities can adversely affect ASL imaging outcomes, making image registration essential. However, research on renal MRI registration, particularly with respect to learning-based techniques, remains limited, with even less focus on renal ASL. Our study proposes a learning-based image registration approach that builds upon VoxelMorph and introduces groupwise inference as a key enhancement. The dataset includes 2448 images of transplanted kidneys (TK) and 2456 images of healthy kidneys (HK). We compared the automatic image registration results with the widely recognized optimization method Elastix. The model’s performance was evaluated using the mean structural similarity index (MSSIM), normalized correlation coefficient (NCC), temporal signal-tonoise ratio (TSNR) of the samples, and the mean cortical signal (CSIM) in perfusion-weighted images, thereby extending the evaluation beyond traditional similarity-based metrics. Our method achieved superior image registration performance, with peak NCC (0.987 ± 0.006) and MSSIM (0.869 ± 0.048) values in the kidney region, significantly surpassing Elastix and the unregistered series (p\ 0.05) on TK and HK datasets. Regularization analysis showed that higher k values (1, 2) produced smoother deformation fields, while moderate k values (0.5, 0.9) balanced smoothness and detail, maintaining low non-positive Jacobian percentages (\1%) comparable to Elastix. Additionally, our method improved CSIM by 14.3% (2.304 ± 1.167) and TSNR by 13.1% (3.888 ± 2.170) in TK, and achieved up to 13.2% (CSIM) and 29.8% (TSNR) enhancements in HK, demonstrating robustness and improved signal quality across datasets and acquisition techniques.
Open Access
Air bubble detection in water flow by means of ai-assisted infrared reflection system
(IEEE, 2024-06-26) Gracia Moisés, Ander; Vitoria Pascual, Ignacio; Imas González, José Javier; Ruiz Zamarreño, Carlos; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This letter introduces an innovative, cost-effective solution for detecting air bubbles in water flow systems using an AI-assisted infrared reflection system. In industries, such as chemical, mechanical, oil, and nuclear, the presence of air bubbles in fluids can compromise both product quality and process efficiency. Our research develops a system that combines infrared optical sensors with machine learning algorithms to detect and quantify bubble presence effectively. The system’s design utilizes infrared emitters and photodetectors arranged around a pipe to capture detailed data on bubble characteristics, which is then analyzed using a support vector machine (SVM) model to predict bubble concentrations. Experimental results demonstrate the system’s ability to accurately identify different levels of bubble presence, offering significant improvements over existing methods. Key performance metrics include a mean squared error of 0.0694, a root mean squared error of 0.2634, and a coefficient of determination of 0.9765, indicating high accuracy and reliability. This approach not only enhances operational reliability and safety but also provides a scalable solution adaptable to various industrial settings.
Open Access
Albumin-based optical and electrochemical biosensors for PFAS detection: a comparison
(Springer, 2023) Moro, G.; Chiavaioli, Francesco; Zubiate Orzanco, Pablo; Del Villar, Ignacio; Baldini, Francesco; De Wael, K.; Moretto, L. M.; Giannetti, Ambra; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The widespread industrial use of per- and polyfluoroalkyl substances (PFAS) have engendered the release of these manmade chemicals in the environment with harmful effects on animal and human health. To monitor PFAS levels in drinking waters, sensitive and versatile sensing strategies are urgently required. Since many perfluoroalkyl carboxylic acids, such as perfluorooctanoic acid (PFOA), are fatty acid-mimic, delipidated human serum albumin (HSA) can be applied as biorecognition element for the design of novel PFAS sensors. Here, two albumin-based biosensing strategies are described and compared: i) a lossy mode resonance (LMR) fiber optic one and ii) an impedimetric portable one developed on screen-printed electrodes. In both biosensing platforms, HSA was covalently immobilized via EDC/NHS chemistry using the carboxylic moieties of the polymeric layers previously deposited at the transducer surface. Afterwards, the conformational changes related to the formation of HSA/PFOA complex were followed considering: i) the LMR spectral shifts for the optical platform and ii) the changes of absolute impedance for the impedimetric one. The performance and future developments of both PFOA biosensors are discussed.
Open Access
Análisis del proceso de llenado de la señal sEMG a medida que aumenta gradualmente la fuerza en el cuádriceps
(Sociedad Española de Ingeniería Biomédica, 2024) Recalde Villamayor, Silvia; Navallas Irujo, Javier; Mariscal Aguilar, Cristina; Rodríguez Falces, Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Objetivos: No existe una comprensión completa del modo en que la señal EMG de superficie se llena progresivamente de potenciales de unidad motora (MUP) a medida que aumenta la fuerza. Intentamos investigar este proceso de llenado de sEMG. Métodos: Se registraron señales EMG superficiales del cuádriceps de sujetos sanos a medida que la fuerza aumentaba gradualmente de 0 a 40% MVC. El proceso de llenado sEMG se analizó midiendo el factor de llenado EMG (calculado a partir de los momentos no centrales de la señal sEMG rectificada). Resultados: (1) Al aumentar gradualmente la fuerza, aparecieron uno o dos saltos bruscos prominentes en la amplitud del sEMG entre el 0 y el 10% de la fuerza MVC en los vastos lateral y medial. (2) Los saltos de amplitud se originaban cuando aparecían en la señal de sEMG unos pocos MUP de gran amplitud, que destacaban claramente de la actividad de sEMG anterior. (3) Cada vez que se producía un salto brusco en la amplitud del sEMG, se iniciaba una nueva fase de llenado del sEMG. Conclusiones: El proceso de llenado del sEMG tuvo una o dos etapas en los músculos vastos, estando el sEMG casi completamente lleno a fuerzas muy bajas (2-12% MVC). Importancia: El factor de llenado es una herramienta prometedora útil para analizar el proceso de llenado EMG.
Open Access
Analog electronics projects to encourage active learning
(IEEE, 2024-08-01) Escribano Simón, Leyre; Tainta Ausejo, Santiago; Erro Betrán, María José; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PINNE2022-UPNA
In this work we present a proposal to include Project Based Learning (PBL) in an Analog Electronics course. For this purpose, several projects have been developed to be implemented in an advanced degree course, covering advanced concepts related to amplifiers, oscillators, and active filters. The results obtained after the rollout of one of these projects in an Industrial Engineering degree course are reported.
Open Access
Analysis of complications associated with peripherally inserted central venous catheters. Prospective observational study
(Universidad de Santander (Colombia), 2024-11-07) Ferraz Torres, Marta; Díez-Revilla, Ana; Plaza-Unzue, Ruth; Corcuera Martínez, María Inés; Ciencias de la Salud; Osasun Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
Los equipos de acceso vascular suelen utilizar guías o algoritmos para determinar el dispositivo de acceso vascular más adecuado según el paciente y la sustancia que se va a administrar. Se supone que las guías permiten al personal identificar a la persona más calificada para insertar el catéter, pero pocos estudios recogen información sobre el desempeño de estas unidades. Objetivo: Este estudio busca identificar la evolución y la tasa de complicaciones de los catéteres centrales de inserción periférica (PICC) en pacientes que requieren acceso vascular. Materiales y Métodos: Estudio observacional prospectivo de tres años de duración. Las variables continuas con distribución normal se compararon mediante la prueba t de Student. Las variables distribuidas con distribución no paramétrica se analizaron con la prueba U de Mann-Whitney. Para las variables categóricas se utilizó la prueba chi cuadrado de dos colas o la prueba exacta de Fisher. Se realizó análisis de regresión para la variable dependiente ¿complicaciones¿. Resultados: El 61,99% (566) de los PICC fueron insertados en pacientes con tratamiento oncológico y una duración media de 136±127,51 días. Los PICC usados en pacientes hematológicos tuvieron una duración media de 144±141,3 días (p=0,438). Las complicaciones más frecuentes fueron la remoción accidental (3,50%, 32, OR 0,581), trombosis (3%, 27, OR 0,752) bacteriemia asociada al catéter venoso central (2,10%, 19, OR, 0,113). Discusión: Las complicaciones relacionadas con los PICC fueron poco frecuentes, siendo la principal la trombosis. Las remociones accidentales fueron frecuentes, una complicación que no ha sido suficientemente analizada en otros estudios. Conclusiones: La inserción y manejo de los PICC por un equipo de acceso vascular permite a las unidades lograr una baja tasa de complicaciones en pacientes oncohematológicos.
Open Access
Analysis of the active inertia power provided by grid-forming strategies during a RoCoF
(IEEE, 2024-08-30) Urtasun Salinas, Ibai; Urtasun Erburu, Andoni; Bautista Portillo, Guillermo Antonio; Marroyo Palomo, Luis; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA2024-11695
Power electronic-based generators are becoming increasingly prevalent in the electrical grid, necessitating their support in disturbances previously handled only by synchronous generators. One of the tests proposed by regulations is to evaluate the response of grid-forming inverters to a Rate of Change of Frequency (RoCoF). However, there is no detailed analysis of the effect of control parameters on the active inertia power. This article presents the temporal response equation of an inverter subject to a RoCoF and introduces the concept of equivalent inertia showing that it also depends on the damping factor. Thanks to this analysis and the flexibility of inverters, the parameter design of existing grid-forming strategies is proposed to achieve the desired active inertia power and system damping ratio. Theoretical analysis and control strategies have been validated by simulation.
Open Access
Analysis of the uncertainty in measurements of polymer pellets using microwave resonant sensors
(IEEE, 2024) Covarrubias-Martínez, Dania; Lobato-Morales, Humberto; Corona-Chávez, Alonso; Ramírez-Cortés, Juan Manuel; Álvarez Botero, Germán Andrés; Méndez-Jerónimo, Gabriela; Kaur Kataria, Tejinder; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The analysis and evaluation of the uncertainty in microwave measurements of some polymer plastic materials in the form of small pellets is presented in this article. Two different resonant sensors, cavity and planar, operating around 2.45 GHz are used to measure the materials. The presented uncertainty analysis is based on the measured resonant parameters from the sensors and represents a statistical tool capable of generating relevant information such as an adequate number of tests, uncertainty levels, correlation coefficient, covariance matrix, and confidence ellipses, which can be highly useful in the analysis of pellet or grained materials using microwave methods, and for fast and accurate decisions involving materials evaluation. It will be shown that a number of 40 tests for each sample is adequate for a stable uncertainty, and due to the E-field distribution and interaction with the samples, the cavity sensor develops lower uncertainty in resonant frequency compared to the planar circuit, thus, it can be a more reliable sensor for polymer pellet measurements.
Open Access
Analyzing implicit gender bias in Optics and Photonics at the predoctoral stage in Spain
(Sociedad Española de Óptica, 2023) Tomás, María-Baralida; Heras, Alba de las; Santamaría Fernández, Beatriz; Gómez Varela, Ana Isabel; Benedi García, Clara; Delgado Pinar, Martina; González Fernández, Verónica; Pérez Herrera, Rosa Ana; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
Los prejuicios de género desempeñan un papel muy importante en áreas relacionadas con la ciencia, la tecnología, la ingeniería y las matemáticas (STEM). La asociación del género con determinados atributos, comportamientos o profesiones conduce a una menor proporción de mujeres en STEM. En el campo de la Óptica y la Fotónica, podemos identificar una disparidad de género entre enfoques técnicos o bioclínicos dentro de la misma área al examinar la autoría de la tesis defendida. En este trabajo, cuantificamos el impacto del sesgo implícito de género en los programas de doctorado relacionados con la Óptica y Fotónica en España. Aquí presentamos un estudio exhaustivo sobre los descriptores UNESCO de las tesis defendidas en el periodo 2015-2020 a través del repositorio de acceso abierto TESEO, donde se recopilan todas las tesis doctorales de las universidades españolas. Se considera el programa de doctorado de cada tesis y se clasifica en una categoría técnica o bioclínica. Con esta clasificación, cuantificamos el número de autores y autoras dentro de cada categoría, y los resultados muestran un claro desequilibrio en la mayoría de los descriptores evaluados: los hombres son más propensos a elegir programas de doctorado técnicos, mientras que las mujeres están mayoritariamente presentes en programas clínicos o biológicos. Esta diferencia se observa incluso en los descriptores en los que ambos sexos están representados por igual. Por un lado, la infrarrepresentación femenina es mayor en "Física", "Astronomía y Astrofísica", "Ciencias de la Tierra y del Espacio" y "Ciencias Tecnológicas". Por el contrario, las áreas de "Química", "Ciencias de la Vida" y "Ciencias Médicas" muestran una distribución más equilibrada entre hombres y mujeres en la mayoría de los descriptores.
Open Access
An antibacterial submicron fiber mat with in situ synthesized silver nanoparticles
(Wiley, 2012) Rivero Fuente, Pedro J.; Urrutia Azcona, Aitor; Goicoechea Fernández, Javier; Rodríguez, Yoany; Corres Sanz, Jesús María; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
This work presents an alternative approachfor fabricating electrospun submicron highly hydrophilicfiber mats loaded with silver nanoparticles. These fiber matsshow a high efficient antibacterial behavior, very attractivefor applications like wound healing and skin regenerationprocesses. The fabrication method is divided in two steps.First, poly(acrylic acid) (PAA) and b-cyclodextrin (b-CD)submicron fibers were electrospun and further stabilizedusing a thermal treatment, yielding stable hydrogel-likefibers with diameters ranging from 100 nm up to severalmicrons. In the second step, silver ions were loaded into thefibers and then reduced to silver nanoparticles in-situ. Theelectrospinning parameters were adjusted to achieve thedesired properties of the fiber mat (density, size) and after-wards, the characteristics of the silver nanoparticles(amount, size, aggregation) were tuned by controlling thesilver ion loading mechanism. Highly biocide surfaces wereachieved showing more than 99.99% of killing efficiency.The two-step process improves the reproducibility and tun-ability of the fiber mats. To our knowledge, this is the firsttime that stable hydrogel fibers with a highly biocide behav-ior have been fabricated using electrospinning.
Open Access
An antibacterial surface coating composed of PAH/SiO2 nanostructurated films by layer by layer
(Wiley, 2010) Urrutia Azcona, Aitor; Rivero Fuente, Pedro J.; Ruete Ibarrola, Leyre; Goicoechea Fernández, Javier; Fernández Valdivielso, Carlos; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería; Ingeniaritza; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC
In this work we propose a novel antibacterial coating composed of SiO2 and the polymer Poly(allylamine hydrochloride) (PAH). The coating was fabricated by the technique Layer-by-Layer (LbL). This technique has already been used in previous works, and it has the advantage that it allows to control the construction of nanosized and well organized multilayer films. Here, the new nanotexturized LbL SiO2 surface acts as antibacterial agent. The fabricated coatings have been tested in bacterial cultures of genus Lactobacillus to observe their antibacterial properties. It has been demonstrated these PAH/SiO2 coating films have a very good antimicrobial behaviour against this type of bacteria.
Open Access
Application of active methodologies based on real cases - university-industry collaboration
(IEEE, 2024-08-01) Andueza Unanua, Ángel María; Urrutia Azcona, Aitor; Erro Betrán, María José; Ruiz Zamarreño, Carlos; Leandro González, Daniel; Elosúa Aguado, César; Socorro Leránoz, Abián Bentor; Goicoechea Fernández, Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PINNE2022-UPNA
During the last academic years, the industrial electronics specialties of the Industrial Engineering Bachelor's Degrees of the Public University of Navarra (UPNA) suffered a gradual loss of students. In order to reverse this trend, a teaching innovation project was designed based on the planned use of active learning methodologies in collaboration with Navarra's leading companies in industrial electronics. The project aims to enhance student learning by making teaching more engaging and practical, as well as boost the social visibility of electronics by improving the perception among students of this strategic industrial sector in the region of Navarra.
Open Access
Application of coherently radiating periodic structures for feeding subarrays in limited-scan arrays
(IEEE, 2023) Juárez, Elizvan; Panduro, Marco A.; Covarrubias, David H.; Reyna, Alberto; Río Bocio, Carlos del; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
This paper presents a new design technique to improve the reduction of phase shifters using sub-arrays and CORPS (coherently radiating periodic structures) technology. The CORPS network generates the values of cophasal excitation with reduced input ports. These values feed an optimal sub-arrays structure. Furthermore, fixed and variable amplifiers allow a low SLL (side lobe level) by using a raised cosine amplitude distribution along sub-arrays inputs. The theoretical model of CORPS-Subarrays, numerical and experimental results of several design cases are presented. The proposed design achieves a ±14° scanning range with a higher reduction of phase shifters than other techniques presented previously in the state of art. This paper illustrates, as a contribution, the complete antenna system based on the fabrication of a prototype and experimental results to analyze the reduction capacity of phase shifters and scanning possibilities of the proposed methodology in antenna arrays. The experimental results of the BFN (beam-forming networks) prototype at 6 GHz for 11 antenna elements and 3 phase shifters are provided. The proposed design achieves a reduction of 72% of phased shifters with ±14° beam scanning and −15 dB of SLL.
Open Access
Artificial intelligence-enhanced metamaterial bragg multilayers for radiative cooling
(Wiley, 2024-10-08) Osuna Ruiz, David; Aznárez-Sanado, Maite; Herrera, Pilar; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua
A full numerical study combining artificial intelligence (AI) methods and electromagnetic simulation software on a multilayered structure for radiative cooling (RC) is investigated. The original structure is made of SiO2/Si nanometer-thick layers that make a Bragg mirror for wavelengths in the solar irradiance window (0.3–4 μm). The structures are then optimized in terms of the calculated net cooling power and characterized via the reflected and absorbed incident light as a function of their structural parameters. This investigation provides with optimal designs of beyond-Bragg, all-dielectric, ultra-broadband mirrors that provide net cooling powers in the order of ≈100 W m−2, similar to the best-performing structures in literature. Furthermore, it explains AI's success in producing these structures and enables the analysis of resonant conditions in metal-free multilayers with unconventional layer thickness distributions, offering innovative tools for designing highly efficient structures in RC.
Open Access
Assessment of mm-wave high resolution inverse SAR imaging both with compact and sparse data
(IEEE, 2023) Iqbal, Muhammad Amjad; Anghel, Andrei; Datcu, Datcu; Ederra Urzainqui, Íñigo; Iriarte Galarregui, Juan Carlos; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Inverse synthetic aperture radar (ISAR) provides images of objects that are rotated with respect to the radar. An efficient image-focusing algorithm is required to generate ISAR images from the echoes of the raw data. In this study, a monostatic model was deployed to collect radar backscattering data in the millimeter (mm) wave band (67-110 GHz) using targets with circular, rectangular, and non-canonical shapes. The ISAR experiments were performed to assess the imaging performance of the three methods. The ISAR image reconstruction implemented in the wave-number (¿ - k) domain solves the target reflectivity and allows the target to be close to the radar. This shows that the mm-wave radar can achieve a sufficient resolution in the range and azimuth dimensions. Finally, we compared the results with those of spherical wavefront compensation (SWFC) and back-projection (BP) methods. The efficiencies of the three methods were tested using compressible data with wavelet-decomposition-based sparse measurements. To demonstrate the performance of the given methods, the point spread function (PSF) for the impulse response of the mm-wave wire was computed. There is a trade-off: the ¿ - k domain loses resolution compared to the SWFC and BP methods but can obtain a satisfactory image at a lower computational cost.
Open Access
Assessment of performance of one-turn inductors in series configuration through a transmission-line modeling approach
(IEEE , 2024) Álvarez Botero, Germán Andrés; Moctezuma-Pascual, Eduardo; Gómez Laso, Miguel Ángel; Torres-Torres, Reydezel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
In this paper, transmission-line theory is applied to implement a physical model for compact one-turn inductors, which simultaneously incorporates the frequency-dependent effects introduced by the conductor skin effect and the loss originated by the coupling with the ground plane. For this purpose, S-parameter measurements are processed to extract the associated parameters, which exhibit scalability with the turn radius. This allows the model to be used for interpolation and extrapolation analyses. In this regard, the device performance is assessed for one-turn inductors in series connection, for different load impedances, and when the turn is narrowed. To validate the proposal, agreement between the model and the experimental transmission line RLGC parameters, the return loss, and the Q-factor is obtained up to 20 GHz.
Open Access
Astrocytic GLUT1 reduction paradoxically improves central and peripheral glucose homeostasis
(American Association for the Advancement of Science, 2024-10-18) Ardanaz, Carlos G.; Cruz, Aida de la; Minhas, Paras S.; Hernández-Martín, Nira; Pozo, Miguel Ángel ; Valdecantos, M. Pilar; Martínez Valverde, Ángela; Villa-Valverde, Palmira; Elizalde-Horcada, Marcos; Puerta, Elena; Ramírez, María J.; Ortega, Jorge E.; Urbiola, Ainhoa; Ederra, Cristina; Ariz Galilea, Mikel; Ortiz de Solórzano, Carlos; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Karsenty, Gerard; Brüning, Jens C. ; Solas, Maite; Ciencias de la Salud; Osasun Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
Astrocytes are considered an essential source of blood-borne glucose or its metabolites to neurons. Nonetheless, the necessity of the main astrocyte glucose transporter, i.e., GLUT1, for brain glucose metabolism has not been defined. Unexpectedly, we found that brain glucose metabolism was paradoxically augmented in mice with astrocytic GLUT1 reduction (GLUT1ΔGFAP mice). These mice also exhibited improved peripheral glucose metabolism especially in obesity, rendering them metabolically healthier. Mechanistically, we observed that GLUT1-deficient astrocytes exhibited increased insulin receptor–dependent ATP release, and that both astrocyte insulin signaling and brain purinergic signaling are essential for improved brain function and systemic glucose metabolism. Collectively, we demonstrate that astrocytic GLUT1 is central to the regulation of brain energetics, yet its depletion triggers a reprogramming of brain metabolism sufficient to sustain energy requirements, peripheral glucose homeostasis, and cognitive function.