Artículos de revista ISC - ISC aldizkari artikuluak

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Open Access
Giant photodegradation rate enabled by vertically grown 1T/2H MoS2 catalyst on top of silver nanoparticles
(Wiley, 2024-08-27) Mouloua, Driss; Rajput, Nitul S.; Lejeune, Michael; Beruete Díaz, Miguel; El Marssi, Mimoun; El Khakani, My Ali; Jouiad, Mustapha; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The exaltation of the photodegradation performance of dichalcogenide MoS2 grown on top of silver nanoparticles (Ag-NPs) is reported on. The fabricated MoS2 nanosheets nucleate vertically from Ag-NPs seeds, enabling the growth of both metallic and semiconductor phases 1T/2H-MoS2. Findings reveal remarkable enhancement of the Raman scattering and an exceptional broadband optical absorption attributed to plasmonic effects induced by the presence of both metallic 1T-MoS2 and Ag-NPS at 2H-MoS2 interfaces. To leverage this effect, photodegradation tests are conducted to remove methyl orange pollutant. Notably, results reveal a significant increase in photodegradation efficiency and rate constant, reaching up to 120% and 550% over pristine 2H-MoS2, respectively. This finding underscores the role of Ag-NPs and 1T-MoS2 tandem to unlock the superior photodegradation properties of vertically aligned 2H-MoS2 toward methyl orange, paving the way for the development of dichalcogenide-based hybrid photocatalyst for wastewater treatment and environmental remediation.
Open Access
Low-Cost multiband four-port phased array antenna for Sub-6 GHz 5G applications with enhanced gain methodology in radio-over-fiber systems using modulation instability
(IEEE, 2024-08-19) Zakeri, Hassan; Azizpour, Rasul; Khoddami, Parsa; Moradi, Gholamreza; Alibakhshikenari, Mohammad; See, Chan H.; Denidni, Tayeb A.; Falcone Lanas, Francisco; Koziel, Slawomir; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Phased array antenna (PAA) technology is essential for applications requiring high gain and wide bandwidth, such as sensors, medical, and 5G. Achieving such a design, however, is a challenging and intricate process that calls for precise calculations and a combination of findings to alter the phase and amplitude of each unit. Furthermore, coupling effects between these PAA structure elements can only be completed with the use of full-wave electromagnetic simulation tools. Due to recent advances, radio-over-fiber (RoF) technology has been positioned as a possible alternative for high-capacity wireless communications. This paper presents a low-cost, multiband Sub-6 GHz 5G PAA with enhanced gain achieved through integration with a new specialized RoF system design to improve PAA performance by using the phenomenon of modulation instability (MI). Optimizing the antenna’s Defected Ground Structure (DGS) leads to even more improvement. To enable operation across three distinct frequency bands (Sub6 GHz n78 band (3-3.8 GHz), n79 band (3.8-5 GHz), and n46 band (5-5.5 GHz)), the proposed antenna design features four elliptical patches strategically positioned at the four sides of the ground plane, providing comprehensive 360◦ coverage in the azimuth plane. Additionally, integrating elliptical slots and upper gaps contributes to improvement. The proposed PAA’s experimentally validated gain values are 5.2 dB, 7.4 dB, and 7.8 dB in the n78, n79, and n46 bands, respectively. For improving the performance of the proposed PAA in RoF systems, anomalous fibers (n2 ̸= 0 and β2 < 0) are employed to consider the modulation instability (MI) phenomenon, which can lead to the generation of the MI gain on the carrier sideband. The true time delay (TTD) technique controls the beam pattern by adjusting the time delay between adjacent radiation elements. Furthermore, the TTD technique utilizes frequency combs for the proposed 4-element array antenna to apply MI gain to all antenna elements.
Open Access
A virtual reality direct-manipulation tool for posing and animation of digital human bodies: an evaluation of creativity support
(MDPI, 2024-07-10) Benbelkheir Núñez, Youssef; Lerga Armendáriz, Álvaro; Ardaiz Villanueva, Óscar; Institute of Smart Cities - ISC
Creating body poses and animations is a critical task for digital content creators, movement artists, and sports professionals. Traditional desktop-based tools for generating 3D poses and animations often lack intuitiveness and are challenging to master. Virtual reality (VR) offers a solution through more intuitive direct-manipulation capabilities. We designed and implemented a VR tool that enables direct manipulation of virtual body parts with inverse kinematics. This tool allows users to pose and animate virtual bodies with one- or two-handed manipulations, while also moving, including bending, jumping, or walking. Our user study demonstrated that participants could produce creative poses and animations using this tool, which we evaluated for creativity support across six factors. Additionally, we discuss further opportunities to enhance creativity support.
Open Access
Estudio del patrón lesional de los traumas graves en Navarra (2010-2019)
(Gobierno de Navarra, 2024-06-26) Arbizu Fernández, Eider; Galbete Jiménez, Arkaitz; Belzunegui Otano, Tomás; Fortún Moral, Mariano; Echarri Sucunza, Alfredo; Ciencias de la Salud; Osasun Zientziak; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
Fundamento. El objetivo de este estudio es describir los traumas graves (TG) en Navarra y analizar sus diferencias por mortalidad, sexo y mecanismo lesional. Material y métodos. Estudio transversal de TG (gravedad ≥3) registrados en Navarra desde 2010 a 2019. Se analizó el tipo de TG, su intencionalidad, mecanismo y región anatómica afectada. Se calculó el riesgo (OR) de TG según distintas variables. Resultados. Se incluyeron 2.609 pacientes con TG, con media de edad 54,7 años (0-101) y 70,9% varones. Predominaron los TG contusos (94,7%) y accidentales (84%) causados por caí-das (46,5%) y accidentes de coche (18,4%). Las mujeres sufrieron más caídas y atropellos y los hombres más accidentes de moto, bicicleta, arma blanca/de fuego y contusiones. La mayoría de TG se registraron en cabeza y tórax. Las lesiones en cabeza fueron significativamente más frecuentes en fallecidos y en mujeres, y las lesiones en tórax en personas fallecidas in situ y en hombres. Las causas más frecuentes de TG en cabeza fueron caídas de baja altura y armas de fuego y, en tórax, los accidentes de coche y las caídas de altura. El riesgo de TG disminuyó con la edad y se multiplicó por 2-3 en pacientes fallecidos. Conclusión. Se han identificado diferencias por sexo en intencionalidad, tipo de traumatismo y mecanismo del TG. Globalmente, las lesiones en cabeza y tórax son más letales, y las abdominales y de extremidades/anillo pélvico se observaron en muertes tempranas, sugiriendo una afectación tan extensa y grave que dificulta su tratamiento y manejo.
Open Access
Emerging technologies and supporting tools for earthquake disaster management: a perspective, challenges, and future directions
(Elsevier, 2024-07-02) Abdalzaher, Mohamed S.; Krichen, Moez; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Seismology is among the ancient sciences that concentrate on earthquake disaster management (EQDM), which directly impact human life and infrastructure resilience. Such a pivot has made use of contemporary technologies. Nevertheless, there is a need for more reliable and insightful solutions to tackle the daily challenges and intricacies of the natural sciences that stakeholders must confront. To consolidate the substantial endeavors in this field, we undertake a comprehensive survey of the interconnected contemporary technologies. More particularly, we analyze the data communication networks (DCNs) and the Internet of Things (IoT), which are among the main infrastructures of seismic networks. In accordance, we present conventional and innovative signal-processing techniques in seismology. Then, we shed light on the evolution of EQ sensors including the acoustic sensors based on optical fibers. Furthermore, we address the role of remote sensing (RS), robots, and drones for EQDM. Afterward, we highlight the social media contribution. Subsequently, a comprehensive elucidation of the diverse optimization techniques employed in seismology and for prolonging seismic networks is presented. Besides, the paper analyzes the important functions that artificial intelligence (AI) can fulfill in several areas of seismology. Lastly, we guide stakeholders on how to prevent natural disasters and preserve human lives.
Open Access
Cátedra Mujer, Ciencia y Tecnología de la UPNA
(Gobierno de Navarra, 2023) Aranguren Garacochea, Patricia; Barrenechea Tartas, Edurne; Catalán Ros, Leyre; Díaz Lucas, Silvia; Jurío Munárriz, Aránzazu; Martínez Ramírez, Alicia; Millor Muruzábal, Nora; Gómez Fernández, Marisol; San Martín Biurrun, Idoia; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2
La Cátedra Mujer, Ciencia y Tecnología de la Universidad Pública de Navarra (UPNA) tiene como objetivo aumentar la participación de las mujeres en campos de ciencia y tecnología. La cultura y la divulgación científicas son el eje principal de la actividad de la Cátedra. Dicha actividad engloba: la representación teatral Yo quiero ser científica, talleres experimentales y conferencias y exposiciones para todos los públicos y edades. Más de 6000 personas han visto la obra de teatro, más de 1500 estudiantes de ESO han participado en los talleres y el material audiovisual ha recibido más de 20000 visitas.
Open Access
Experimental and computational investigation of passive heat exchangers to enhance the performance of a geothermal thermoelectric generator
(Elsevier, 2024) Pascual Lezaun, Nerea; Alegría Cía, Patricia; Araiz Vega, Miguel; Martínez Echeverri, Álvaro; Astrain Ulibarrena, David; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
Thermoelectric devices hold significant promise for generating electricity from geothermal heat, enabling the powering of measuring equipment in remote locations without the need for moving parts. Nevertheless, most developed geothermal thermoelectric generators employ fans and pumps to enhance heat transfer, thereby compromising the robustness and reliability inherent to thermoelectricity. Furthermore, there is a lack of research on passive heat exchangers for geothermal thermoelectric generators, particularly in studying their operation under a wide range of meteorological conditions. Therefore, this paper conducts a comprehensive analysis of passive heat exchangers for the cold side of the generators. Phase-change-based heat exchangers differing in their length and fluid are studied experimentally, along with a fin dissipator. Additionally, the influence of wind velocity on heat transfer and mechanical requirements is further explored through a Computational Fluid Dynamics model. The most significant outcome is quantifying the impact of the design parameters and operational variables on the electrical production of the thermoelectric generator. Accordingly, this research aims to broaden the application of these generators to extreme environments, such as Deception Island in Antarctica. Under average operational conditions, generators incorporating 400 mm water heat pipes generate 0.95 W per thermoelectric module, while those incorporating heat pipes with methanol achieve an average of 0.70 W. Moreover, water and methanol-based systems produce 120% and 60% more power than generators using a fin dissipator. Nonetheless, for temperatures beyond -6.5 °C, water might freeze and the methanol-based heat exchangers become more suitable.
Open Access
The integration of mechanical energy absorbers into rollover protective structures to improve the safety of agricultural tractors in the event of rollover
(MDPI, 2024) Alfaro López, José Ramón; Pérez Ezcurdia, Amaya; Latorre Biel, Juan Ignacio; Arana Navarro, Ignacio; Benito Amurrio, Marta; Villanueva Roldán, Pedro; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA1912
The combination of safety belts and rollover protective structures (ROPSs) is key in improving the safety of agricultural tractors in the event of rollover. However, we also have the opportunity to enhance the security provided by each ROPS; one such example is the combination of this safety device with adequate mechanical energy absorbers (MEAs). Inexpensive disc-shaped MEAs can be included in the anchoring points of a ROPS onto the chassis of a tractor. Three configurations of ROPS combined with MEAs were tested during the application of loads that simulated the effects of side rollover in the vehicle. The tested configurations included a blank MEA as a reference case alongside a single MEA and a stack assembly containing both elements. The results of the tests show that both the deformation of the ROPS itself and the strain energy are larger in the case of blank MEAs; thus, there is also a risk that the clearance zone will be infringed upon and that the protective structure will collapse. We can conclude that the implementation of an appropriate MEA in ROPS reduces the deformation of the ROPS itself and its strain energy in cases of vehicle rollover; hence, the safety provided by such protection systems may be improved at a low cost.
Open Access
Single-mode-multimode-single-mode fiber (SMS): exploring environmental sensing capabilities
(IEEE, 2024-08-16) Díaz Lucas, Silvia; Armendáriz Ballesteros, Mikel; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
In this paper, we study the environmental sensing capabilities of a Single-Mode-Multimode-Single-Mode (SMS) fiber in a simple low-cost configuration. SMS fibers exhibit sensitivity to temperature, humidity, refractive index and strain, making them suitable for numerous applications in telecommunications, environmental monitoring, and more. Experimental results demonstrate that the sensor achieves a maximum temperature sensitivity of 4.53 nm/°C. Additionally, SMS fibers can also work as humidity sensors by absorbing or releasing moisture, leading to variations in the refractive index. Monitoring these changes allows for precise humidity measurements, with a sensitivity of 0.1548 nm/%RH. Moreover, SMS fibers show a refractive index sensitivity of 39.65 nm/RIU and strain sensitivities as high as 1.062 nm/¿¿, indicating good performance.
Open Access
Optical fiber sensor for water velocity measurement in rivers and channels
(Nature Research, 2024) Rodríguez Rodríguez, Armando; Diéguez Elizondo, Pedro; Urroz Unzueta, José Carlos; Bravo Acha, Mikel; López Rodríguez, José Javier; López-Amo Sáinz, Manuel; Ingeniería; Ingeniaritza; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
In this work, optical fiber Bragg grating sensors were used to measure water velocity and examine how it was distributed in open channels. Several types of coatings were incorporated into the design of the sensors to examine their effects on the strain that the fibers experienced as a result of the water flow. Due to their low elastic coefficient, which reduced the hysteresis, the results indicated that the aluminum- and acrylate-coated fibers had the best performance. ANSYS-CFX V2020 R2 software was used to model the strain encountered by the fibers under various flow rates to assess the performance of the FBG sensors. The calculations and actual data exhibited good convergence, demonstrating the accuracy of the FBG sensors in determining water velocity. The study illustrated the usability of the proposal in both scenarios by contrasting its application in rivers and channels.
Open Access
Metrics for dataset demographic bias: a case study on facial expression recognition
(IEEE, 2024) Domínguez Catena, Iris; Paternain Dallo, Daniel; Galar Idoate, Mikel; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Universidad Pública de Navarra - Nafarroako Unibertsitate Publikoa
Demographic biases in source datasets have been shown as one of the causes of unfairness and discrimination in the predictions of Machine Learning models. One of the most prominent types of demographic bias are statistical imbalances in the representation of demographic groups in the datasets. In this paper, we study the measurement of these biases by reviewing the existing metrics, including those that can be borrowed from other disciplines. We develop a taxonomy for the classification of these metrics, providing a practical guide for the selection of appropriate metrics. To illustrate the utility of our framework, and to further understand the practical characteristics of the metrics, we conduct a case study of 20 datasets used in Facial Emotion Recognition (FER), analyzing the biases present in them. Our experimental results show that many metrics are redundant and that a reduced subset of metrics may be sufficient to measure the amount of demographic bias. The paper provides valuable insights for researchers in AI and related fields to mitigate dataset bias and improve the fairness and accuracy of AI models.
Open Access
Review on the scientific and technological breakthroughs in thermal emission engineering
(American Chemical Society, 2024) Vázquez Lozano, Juan Enrique; Liberal Olleta, Íñigo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The emission of thermal radiation is a physical process of fundamental and technological interest. From different approaches, thermal radiation can be regarded as one of the basic mechanisms of heat transfer, as a fundamental quantum phenomenon of photon production, or as the propagation of electromagnetic waves. However, unlike light emanating from conventional photonic sources, such as lasers or antennas, thermal radiation is characterized for being broadband, omnidirectional, and unpolarized. Due to these features, ultimately tied to its inherently incoherent nature, taming thermal radiation constitutes a challenging issue. Latest advances in the field of nanophotonics have led to a whole set of artificial platforms, ranging from spatially structured materials and, much more recently, to time-modulated media, offering promising avenues for enhancing the control and manipulation of electromagnetic waves, from far- to near-field regimes. Given the ongoing parallelism between the fields of nanophotonics and thermal emission, these recent developments have been harnessed to deal with radiative thermal processes, thereby forming the current basis of thermal emission engineering. In this review, we survey some of the main breakthroughs carried out in this burgeoning research field, from fundamental aspects to theoretical limits, the emergence of effects and phenomena, practical applications, challenges, and future prospects.
Embargo
Finite determinization of fuzzy automata using a parametric product-based t-norm
(Elsevier, 2024) Micic, Ivana; Stanimirovic, Stefan; González de Mendívil Moreno, José Ramón; Ciric, Miroslav; Jancic, Zorana; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
This paper presents a novel approach for the approximate determinization of fuzzy automata over the product structure. We introduce the parametric modification of the product t-norm in the pre-determinization setting. On the one hand, the behavior of a fuzzy automaton over the parametric t-norm differs from the behavior of the fuzzy automaton over the product t-norm only in words with a degree of acceptance below the given parameter. However, using the parametric t-norm, we obtain an algorithm that outputs a finite minimal deterministic fuzzy automaton whose behavior differs from the starting fuzzy automaton described above. By setting the parameter to a sufficiently small value, the proposed algorithm provides a deterministic fuzzy automaton with behavior that differs insignificantly from the starting fuzzy automaton, as the difference is achieved only for words accepted by the starting fuzzy automaton with an insignificant value. As a tradeoff, the proposed approach provides finite determinization, even when all other determinization methods would result in an infinite deterministic automaton. We support this fact with an illustrative example.
Open Access
Design and analysis of a low profile millimeter-wave band Vivaldi MIMO antenna for wearable WBAN applications
(IEEE Xplore Digital Library, 2024) Ahmad, Jawad; Hashmi, Mohammad; Bakytbekov, Azamat; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The development of a reliable Wireless Body Area Network (WBAN) relies significantly on the quality of wearable antennas. Therefore, this paper proposes a low-profile four-element Multi-Input- Multi-Output (MIMO) antenna for wearable millimeter-wave (mm-wave) WBAN applications. The MIMO antenna structure incorporates a standardVivaldi antenna and a frequency-selective surface that encompasses the 28 GHz and 30 GHz of the mm-wave band with a 36.44% fractional bandwidth. It offers inter-element isolation of less than -20 dB in a compact space of 16 x 20 mm2. Conformability analysis, along with testing on Gustav’s model chest, hand, and leg, was evaluated in terms of the antenna impedance bandwidth, gain, efficiency, and radiation pattern. The simulated characteristics of the MIMO antenna were tested through measurements in free space and on the human body using a prototype of the antenna. Furthermore, the MIMO antenna exhibits a low envelope correlation coefficient of less than 0.24, high diversity gain of greater than 9.95 dB, and an acceptable total active reflection coefficient of less than -10 dB. To ensure safety, the Specific Absorption Rate (SAR) analysis revealed acceptable levels of 0.397 and 0.267 (W/kg) at 28 GHz and 30 GHz, respectively. The proposed MIMO design is suitable for wearable WBAN applications owing to its small size, consistent gain, and compatibility with the human body in terms of a constant impedance bandwidth and end-fire radiation pattern.
Embargo
The first and second phases of the muscle compound action potential in the thumb are differently affected by electrical stimulation trains
(American Physiological Society, 2024) Lanfranchi, Clément; Rodríguez Falces, Javier; Place, Nicolas; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Sarcolemmal membrane excitability is often evaluated by considering the peak-to-peak amplitude of the compound muscle action potential (M wave). However, the first and second M-wave phases represent distinct properties of the muscle action potential, which are differentially affected by sarcolemma properties and other factors such as muscle architecture. Contrasting with previous studies in which voluntary contractions have been used to induce muscle fatigue, we used repeated electrically induced tetanic contractions of the adductor pollicis muscle and assessed the kinetics of M-wave properties during the course of the contractions. Eighteen participants (24 ± 6 yr; means ± SD) underwent 30 electrically evoked tetanic contractions delivered at 30 Hz, each lasting 3 s with 1 s intervals. We recorded the amplitudes of the first and second M-wave phases for each stimulation. During the initial stimulation train, the first and second M-wave phases exhibited distinct kinetics. The first phase amplitude showed a rapid decrease to reach ~59% of its initial value (P < 0.001), whereas the second phase amplitude displayed an initial transient increase of ~19% (P ¼ 0.007). Within subsequent trains, both the first and second phase amplitudes consistently decreased as fatigue developed with a reduction during the last train reaching ~47% of its initial value (P < 0.001). Analyzing the first M wave of each stimulation train unveiled different kinetics for the first and second phases during the initial trains, but these distinctions disappeared as fatigue progressed. These findings underscore the interplay of factors affecting the M wave and emphasize the significance of separately scrutinizing its first and second phases when assessing membrane excitability adjustments during muscle contractions.
Open Access
Thermoelectrics working in favour of the natural heat flow to actively control the heat dissipation
(Elsevier, 2024) Alzuguren Larraza, Iñaki; Aranguren Garacochea, Patricia; Casi Satrústegui, Álvaro; Erro Iturralde, Irantzu; Rodríguez García, Antonio; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In sectors such as electronics, photonics and HVAC and refrigeration, heat dissipation has a major impact in their performance. However, there is generally not much control over this effect. Thus, one way of making these units more controllable would be to include thermoelectric technology in the heat dissipation systems. Therefore, in this work, a computational model based on the resistance-capacitance model to solve a thermoelectrically aided heat dissipation system is proposed, considering all the thermoelectric effects, temperature dependent thermoelectric properties and four temperature levels. Besides, an experimental prototype has been built to assess the real performance of thermoelectric modules (TEM) working under different operating conditions. Additionally, these results have been used to validate the computational model, obtaining maximum errors of ±6% in the main parameters. Moreover, the computational model has been used to simulate the effect of modifying the temperature difference between the hot and cold sources and the thermal resistances of the heatsinks located on both sides of the TEMs. The results show that the thermoelectrically aided dissipation system would be beneficial when working with low temperature differences and low thermal resistance values of the heatsinks, especially on the heatsink located on the hot side of the TEMs.
Open Access
Spatial MIMO channel characterization under different vehicular distributions
(IEEE, 2024) Rodríguez Corbo, Fidel Alejandro; Celaya Echarri, Mikel; Shubair, Raed M.; Falcone Lanas, Francisco; Azpilicueta Fernández de las Heras, Leyre; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Considering the large benefits brought by multipleinput- multiple-output (MIMO) technologies in vehicular communications, the analysis of MIMO channel characteristics using accurate and efficient channel models for these scenarios has become crucial. In this work, an intensive analysis of the MIMO channel characteristics in a mmWave vehicle-to-infrastructure (V2I) communication link with different vehicular distributions is performed. For that purpose, an in-house deterministic simulation channel model with an embedded MIMO channel approach has been developed. Experimental measurements in the same vehicular scenario have been performed to validate the proposed channel simulation technique. Variations in the capacity of the MIMO system have been analyzed in relation to different channel metrics, obtaining that the main contributors are the Signal-to- Noise Ratio (SNR) and the Angular Spread (AS).
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
Low-frequency electromagnetic harvester for wind turbine vibrations
(Elsevier, 2024) Castellano Aldave, Jesús Carlos; Plaza Puértolas, Aitor; Iriarte Goñi, Xabier; Carlosena García, Alfonso; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Ingeniaritza; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this paper we describe and fully characterize a novel vibration harvester intended to harness energy from the vibration of a wind turbine (WT), to potentially supply power to sensing nodes oriented to structural health monitoring (SHM). The harvester is based on electromagnetic conversion (EM) and can work with vibrations of ultra-low frequencies in any direction of a plane. The harvester bases on a first prototype already disclosed by the authors, but in this paper, we develop an accurate model parameterized by a combination of physical parameters and others related to the geometry of the device. The model allows predicting not only the power generation capabilities, but also the kinematic behaviour of the harvester. Model parameters are estimated by an identification procedure and validated experimentally. Last, the harvester is tested in real conditions on a wind turbine.
Open Access
Linear fiber laser configurations for optical concentration sensing in liquid solutions
(MDPI, 2024) Soares, Liliana; Pérez Herrera, Rosa Ana; Novais, Susana; Ferreira, António; Silva, Susana; Frazão, Orlando; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
In this study, different configurations based on linear fiber lasers were proposed and experimentally demonstrated to measure the concentration of liquid solutions. Samples of paracetamol liquid solutions with different concentrations, in the range from 52.61 to 201.33 g/kg, were used as a case-study. The optical gain was provided by a commercial bidirectional Erbium-Doped Fiber Amplifier (EDFA) and the linear cavity was obtained using two commercial Fiber Bragg Gratings (FBGs). The main difference of each configuration was the coupling ratio of the optical coupler used to extract the system signal. The sensing head corresponded to a Single-Mode Fiber (SMF) tip that worked as an intensity sensor. The results reveal that, despite the optical coupler used (50:50, 60:40, 70:30 or 80:20), all the configurations reached the laser condition, however, the concentration sensing was only possible using a laser drive current near to the threshold value. The configurations using a 70:30 and an 80:20 optical coupler allowed paracetamol concentration measurements with a higher sensitivity of (−3.00 ± 0.24) pW/(g/kg) to be performed. In terms of resolution, the highest value obtained was 1.75 g/kg, when it was extracted at 20% of the output power to the linear cavity fiber laser configuration.