Artículos de revista ISC - ISC aldizkari artikuluak

Permanent URI for this collection

http://hdl.handle.net/2454/20317

Browse

Now showing 1 - 20 of 812

Embargo
Shedding light on preservice and inservice school teachers' beliefs and attitudes regarding mathematics
(Springer Nature, 2025-09-10) Moler Cuiral, José Antonio; Celi, Valentina; Regoliosi, Luigi; Gil Clemente, Elena; Lizasoain Iriso, María Inmaculada; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2
The psychological dimensions of the teaching of mathematics are attracting increasing attention in mathematics education research. This study presents a crossnational comparative study of the mathematical identities of a sample of preservice and inservice primary teachers in the partner institutions (in Italy, France and Spain) of a specific European project in the area of innovation. Given that preservice and inservice teachers' mathematical identities have been forged throughout diverse experiences during their school years, and are informed, among other factors, by their beliefs and attitudes, a questionnaire was designed and delivered seeking to identify preservice and inservice teachers' experiences, beliefs and attitudes towards mathematics and mathematics teaching. This paper presents the manner in which this questionnaire has been used to set up diverse profiles of preservice and inservice primary teachers. Moreover, a deep analysis of the responses given to the questionnaire has allowed us to identify specific particularities which may be associated with the different countries involved in the project, distinguishing these from their shared beliefs and attitudes. In addition, implications for the design of interventions capable of promoting trust, enjoyment, and human expression in the mathematics education of preservice and inservice teachers are presented.
Open Access
Effects of scoring system manipulation on tactical, conditional, and emotional responses in rugby union academy players
(Palacký University in Olomouc, 2025-09-08) Sorreluz-Uria, Juan; Los Arcos Larumbe, Asier; Aginaga García, Jokin; González-Artetxe, Asier; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
Background: rugby union coaches design small-sided games (SSGs) by altering task conditions to guide players toward the desired objectives. Placing greater value on scoring a try in the centre of the in-goal area may encourage players to play more centrally. Objective: to compare the tactical and conditional responses, along with perceptions of enjoyment and competence, of rugby union academy players during regular (SSGREG) and conditioned (SSGCOND) SSGs. Methods: Sixteen U18 male rugby union players competed in two 4 × 5 min eight-a-side games (219 m2 per player) with (SSGCOND) and without (SSGREG) triple point value in the central part of the in-goal area. Players' tactical (central tendency and approximate entropy measures of surface area, length, width, dyads, and stretch and spatial exploration indices) and conditional (total distance travelled and distances at different speed zones) responses were assessed using GPS data. Players also rated their enjoyment and perceived competence for each SSG. Results: young rugby union players significantly (p < .05) occupied less space (surface area: r = .13; length: r = .05; width: r = .24), played closer together (dyads: r = .16; stretch index: r = .14) and explored less (r = .63) in the SSGCOND than in the SSGREG, with no differences in entropy measures (p > .05) across task conditions. They also ran significantly (p < .001) more overall (d = 1.21) and at low-to-medium speed (d = 0.85) but not at higher speeds (p > .05) in the conditioned scenario than in the regular one. Players' perceptions of enjoyment and competence did not differ (p > .05) across SSGs. Conclusions: manipulating the scoring system in rugby union SSGs encouraged players to play more compactly and run more, with no changes in distances travelled at highest speeds nor in perceptions of enjoyment and competence. Thus, academy coaches can benefit from the tactical impact of this manipulation without exceeding habitual high-speed running demands or impairing players' subjective experience.
Embargo
When reviews speak through pictures: visual content and its influence on helpfulness
(Elsevier, 2025-10-01) Vidaurreta Apesteguía, Paula; Alzate Barricarte, Miriam; Arce Urriza, Marta; Armendáriz Íñigo, José Enrique; D'Acunto, David; Gestión de Empresas; Enpresen Kudeaketa; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Research in Business and Economics - INARBE; Institute of Smart Cities - ISC
This research investigates the impact of service quality dimensions displayed in user-generated photos on their perceived helpfulness. Building on the SERVQUAL model and the Haywood-Farmer framework, we propose a novel methodology that integrates advanced image-to-caption techniques with topic modeling algorithms and negative binomial regression to extract, interpret, and quantify the effect of visuals on review helpfulness. Two studies were conducted relying on two sample of online reviews from two tourism-related service types (5,293 hotel reviews from Cancun, Mexico, and 11,252 spa and wellness reviews from Iceland). The results underline the role of visuals in affecting review helpfulness, with aspects such as “Room” “Leisure” and “Hotel Outdoor” positively impacting review helpfulness in hotels and “Natural Water Features” emerging as significant in spa and wellness reviews. Overall, this study underscores the relevance of tangibles and empathy in service evaluation, providing actionable strategies for businesses to optimize visual content.
Open Access
Impact of strain gauge misalignment and model parameters on load estimation in wind turbines
(Elsevier, 2026-01-15) Bacaicoa Díaz, Julen; Iriarte Goñi, Xabier; Aginaga García, Jokin; Plaza Puértolas, Aitor; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Accurate load estimation in wind turbines is important for understanding the structural behaviour and optimising performance. Loads are commonly measured using strain gauges, but the process is strongly based on accurate placement and alignment. This work explores the influence of geometric, material, misplacement, and misalignment parameters on the performance of different strain gauge configurations for obtaining load estimates. An analytical model for a single gauge is presented which establishes the relationship between exerted loads and measured strain. Using second-order approximations, the sensitivities of the estimated loads are calculated in terms of the uncertainty of the model parameters. The model allows to calculate how the secondary loads affect the estimation of those of interest, which is particularly useful in wind turbines where all three forces and three moments occur simultaneously. When estimating a single load, analytic results show that sensitivities to geometric and material parameters remain consistent regardless of secondary loads, while sensitivities to gauge bonding parameters reveal a cross-talk effect. As these sensitivity results depend on the model parameters and the instantaneous values of the secondary loads (which vary with time) the sensitivities will strongly depend on the application cases. In this paper a horizontal-axis wind turbine is simulated, calculating the loads at the Low Speed Shaft and the Tower Base. The sensitivity results for these subsystems using Montecarlo simulations show that while some loads can be precisely estimated, other loads will be very poorly estimated even when the gauges are bonded with tiny misalignment errors.
Open Access
Machine learning-based state-of-health estimation of battery management systems using experimental and simulation data
(MDPI, 2025-07-11) Al-Rahamneh, Anas; Izco Berastegui, Irene; Serrano Hernández, Adrián; Faulín Fajardo, Javier; Institute of Smart Cities - ISC
In pursuit of zero-emission targets, increasing sustainability concerns have prompted urban centers to adopt more environmentally friendly modes of transportation, notably through the deployment of electric vehicles (EVs). A prominent manifestation of this shift is the transition from conventional fuel-powered buses to electric buses (e-buses), which, despite their environmental benefits, introduce significant operational challenges—chief among them, the management of battery systems, the most critical and complex component of e-buses. The development of efficient and reliable Battery Management Systems (BMSs) is thus central to ensuring battery longevity, operational safety, and overall vehicle performance. This study examines the potential of intelligent BMSs to improve battery health diagnostics, extend service life, and optimize system performance through the integration of simulation, real-time analytics, and advanced deep learning techniques. Particular emphasis is placed on the estimation of battery state of health (SoH), a key metric for predictive maintenance and operational planning. Two widely recognized deep learning models—Multilayer Perceptron (MLP) and Long Short-Term Memory (LSTM)—are evaluated for their efficacy in predicting SoH. These models are embedded within a unified framework that combines synthetic data generated by a physics-informed battery simulation model with empirical measurements obtained from real-world battery aging datasets. The proposed approach demonstrates a viable pathway for enhancing SoH prediction by leveraging both simulation-based data augmentation and deep learning. Experimental evaluations confirm the effectiveness of the framework in handling diverse data inputs, thereby supporting more robust and scalable battery management solutions for next-generation electric urban transportation systems.
Open Access
Fresh, mechanical, and microstructural properties of sustainable mortars made of two recycled sands from construction and demolition wastes
(American Society of Civil Engineers, 2025-04-28) Seco Meneses, Andrés; Martín Antunes, Miguel Ángel; Espuelas Zuazu, Sandra; Marcelino Sádaba, Sara; Prieto Cobo, Eduardo; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua
This paper analyses the ability of two recycled sands (RSs) from concrete (CON) and masonry (MAS) wastes for the manufacture of mortars for the construction industry. Manufactured sand (MS) was substituted by both RSs at the rates of 25%, 50%, 75%, and 100%. CON combinations did not demonstrate any correlation between workability and the MS replacement ratio, whereas MAS combinations exhibited a direct relationship between these factors. A decrease in the starting and final setting times was observed for both RS combinations and, in general, longer total setting times. CON combinations showed mechanical strength increases for substitution rates between 25% and 50%, whereas MAS reached improved mechanical strength at 25%. Scanning electron microscopy-energy dispersive X-ray (SEM-EDX)-demonstrated tests allowed for mortar microstructure differences and hydration product formation. Thermogravimetric analysis/derivative thermogravimetry (TG/DTG) tests showed hydrated cementitious compounds' formation differences and the consumption of Portlandite between combinations and their evolution during curing.
Open Access
Lossy mode resonance and hyperbolic mode resonance-based optical sensors by means of Y3Fe5O12 and SrTiO3 films deposition on planar substrates
(IEEE, 2025-07-02) Correa Fernández, Ángel; Gallego Martínez, Elieser Ernesto; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This letter describes the fabrication of sensor devices based on lossy mode resonance (LMR) and hyperbolic mode resonance (HMR) using for the first time as generating materials of the optical resonances both, yttrium iron garnet (Y3Fe5O12) and strontium titanate (SrTiO3) with a film thickness of 739.2 and 158.7 nm for Y3Fe5O12 (YIG) and SrTiO3, respectively. First-order resonances were observed at the visible region of the electromagnetic spectrum for both materials, LMR and HMR phenomena. RF sputtering deposition was used to fabricate metal oxide thin films on coverslips in a planar waveguide configuration, the Au metallic thin films were deposited by pulsed dc sputtering in a magnetron system from Moorfield. All devices were characterized under different surrounding medium refractive index. Sensitivities achieved values of 5862 and 5865 nm/RIU (refractive index unit) for HMR versions of Y3Fe5O12 and SrTiO3r, respectively. In addition, the response of the sensors to relative humidity and different ethanol concentrations was evaluated. The best results correspond to the Y3Fe3O3-based sensor, with a sensitivity of 0.2 nm/ppm and a limit of detection (LOD) of 183 ppm for ethanol, and 64 nm/%RH for RH, with an LOD of 2.23%RH, and because its resonance does not vanish unlike SrTiO3.
Open Access
Resonance-based optical gas sensors
(IEEE, 2025-07-02) Gallego Martínez, Elieser Ernesto; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Gas sensors play a critical role in numerous human activities. Their necessity continues to grow across diverse fields as technological advancements drive demand for precision agriculture and bioengineering among other applications. Among existing sensor technologies, optical gas sensors stand out due to their ability to operate remotely in high-risk environments while remaining unaffected by electromagnetic interference. Resonance-based optical sensors offer targeted gas detection through the functionalization of their sensitive surfaces. This work focuses on reviewing the state of the art in resonance-based optical gas sensors (ROGSs), addressing their fundamental principles, recent advances in fabrication processes, waveguide designs, and materials employed both for resonance generation and as sensitive coatings. In addition, the review examines achieved sensitivity, emerging applications, and key developments in the field, including those efforts on improving ROGS performances by means of artificial intelligence techniques. The study encompasses optical sensors leveraging surface plasmon resonance, lossy mode resonance, and hyperbolic mode resonance¿the latter representing a notable breakthrough in recent years as a particular case of Bloch surface waves.
Open Access
HMR-based optical gas detection with CuO and ZnO coatings
(IEEE, 2025-07-02) Gallego Martínez, Elieser Ernesto; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This work presents the fabrication of hyperbolic mode resonance-based optical sensors by means of sputtered copper oxide (CuO) and zinc oxide (ZnO), and the study of their performance for gas sensing purposes. Two sensors were fabricated in a planar waveguide configuration with an intermediate gold thin film, and resonances were observed in the visible region of the electromagnetic spectrum. Both materials were analyzed with X-ray diffraction techniques, and their response was characterized by different concentrations of a group of gases comprised of nitric oxide, acetylene (C2H2), ethanol, carbon dioxide, and relative humidity. The best performance corresponds to the CuO sensor for C2H2 gas, presenting a sensitivity of 1.11 nm/parts per million (ppm) and a limit of detection of 12.6 ppb, with response and recovery times of 70 and 68 s, respectively. ZnO-based sensors allowed for a comprehensive study of ethanol in a range of thousands of ppm, while CuO-based sensors showed exceptional sensitivity for most gases in the range of a few ppm. All measurements were performed at room temperature.
Open Access
Non-line-of-sight 300 GHz band wireless link enabled by a frequency dependent reflective surface
(IEEE, 2025-05-01) Dutin, Frédéric; Beaskoetxea Gartzia, Unai; Torres Landívar, Víctor; Szriftgiser, Pascal ; Teniente Vallinas, Jorge; Ducournau, Guillaume; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Reconfigurable intelligent surface is a promising technology for the up-coming sixth-generation (6G) of cellular communication networks. In this context, an experimental study of specular and nonspecular reflections of a reflective surface (RS) by scattering parameter measurements in the 300 GHz range is presented. Here, we compare the insertion loss of a fixed and passive RS at its optimal output deflection angle with respect to the specular reflection on a metallic plate. We propose a methodology to assess the losses induced by the surface and validate the use of the device within a THz link. At its best, around 290 GHz, the surface insertion loss is less than 3 dB compared to the metallic plate. We then investigate a non-line-of-sight (LoS) THz link operating in QSPK and QAM-16 coherent transmission using the RS. Data rates up to 10 Gbits/s for QSPK and 20 Gbits/s for QAM-16 are obtained. This is, to the best authors knowledge, the first demonstration of a NLoS THz data-link including such RS.
Open Access
Hybrid modelling and identification of mechanical systems using Physics-Enhanced Machine Learning
(Elsevier, 2025-11-15) Merino Olagüe, Mikel; Iriarte Goñi, Xabier; Castellano Aldave, Jesús Carlos; Plaza Puértolas, Aitor; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Obtaining mathematical models for mechanical systems is a key subject in engineering. These models are essential for calculation, simulation and design tasks, and they are usually obtained from physical principles or by fitting a black-box parametric input-output model to experimental data. However, both methodologies have some limitations: physics based models may not take some phenomena into account and black-box models are complicated to interpretate. In this work, we develop a novel methodology based on discrepancy modelling, which combines physical principles with neural networks to model mechanical systems with partially unknown or unmodelled physics. Two different mechanical systems with partially unknown dynamics are successfully modelled and the values of their physical parameters are obtained. Furthermore, the obtained models enable numerical integration for future state prediction, linearization and the possibility of varying the values of the physical parameters. The results show how a hybrid methodology provides accurate and interpretable models for mechanical systems when some physical information is missing. In essence, the presented methodology is a tool to obtain better mathematical models, which could be used for analysis, simulation and design tasks.
Embargo
Dispersion effects in thermal emission from temporal metamaterials: high-frequency cutoffs
(Optica, 2025-02-03) Vertiz Conde, Amaia; Liberal Olleta, Íñigo; Vázquez Lozano, Juan Enrique; 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 latest breakthroughs in time-varying photonics are fueling novel, to the best of our knowledge, thermal emission phenomena, e.g., showing that the dynamic amplification of quantum vacuum fluctuations, induced by the time modulation of material properties, enables a mechanism to surpass the blackbody spectrum. So far, this issue has only been investigated under the assumption of non-dispersive time modulations. In this work, we identify the existence of a nonphysical diverging behavior in the time-modulated emission spectra at high frequencies and prove that it is actually attributed to the simplistic assumption of a non-dispersive (temporally local) response of the time modulation associated with memory-less systems. Accordingly, we upgrade the theoretical formalism by introducing a dispersive response function, showing that it leads to a high-frequency cutoff, thereby eliminating the divergence and hence allowing for the proper computation of the emission spectra of time-modulated materials.
Open Access
An acoustic levitator design for suspending cosmic dust analogues and aerosol particles in light scattering experiments
(Springer, 2025-04-22) Colin, Ángel; Muñoz, O.; García-Izquierdo, Francisco José; Frattin, E.; Martikainen, J.; Gray, Z.; Ramos, J. L.; Jiménez, J.; Tobaruela, A.; Gómez-López, J. M.; Bustamante, I.; Gómez, J. C.; Moreno, F.; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
We present a design of an acoustic levitator composed of 35 ultrasonic transducers operating at 40 kHz confgured to form a spherical cavity. The acoustic radiation force measured experimentally in the center of the cavity is Frad ≈ 9.6mN, enough for levitating spheres as well as irregular particles of diferent materials of up to ~50 mg. Levitation tests have been performed with particles of diferent geometries and compositions, including liquid droplets and minerals relevant in studies of atmospheric aerosol and cosmic dust. This device has been deployed in the center of a polar nephelometer set-up to conduct studies of light scattering by irregular solid particles and liquid droplets. Test experiments have been carried out using a 1.5 mm diameter NBK- 7 glass sphere, for which three elements of the scattering matrix have been measured as functions of the scattering angle using a 647 nm diode laser. Mie theory calculations of the scattering matrix elements at this wavelength agree well with the measurements, demonstrating the functionality of the whole device.
Open Access
Method to use transport microsimulation models to create synthetic distributed acoustic sensing datasets
(MDPI, 2025-05-07) Robles Urquijo, Ignacio; Benavente, Juan; Blanco García, Javier; Diego González, Pelayo; Loayssa Lara, Alayn; Sagüés García, Mikel; Rodríguez Cobo, Luis; Cobo, Adolfo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This research introduces a new method for creating synthetic Distributed Acoustic Sensing (DAS) datasets from transport microsimulation models. The process involves modeling detailed vehicle interactions, trajectories, and characteristics from the PTV VISSIM transport microsimulation tool. It then applies the Flamant-Boussinesq approximation to simulate the resulting ground deformation detected by virtual fiber-optic cables. These synthetic DAS signals serve as large-scale, scenario-controlled, labeled datasets on training machine learning models for various transport applications. We demonstrate this by training several U-Net convolutional neural networks to enhance spatial resolution (reducing it to half the original gauge length), filtering traffic signals by vehicle direction, and simulating the effects of alternative cable layouts. The methodology is tested using simulations of real road scenarios, featuring a fiber-optic cable buried along the westbound shoulder with sections deviating from the roadside. The U-Net models, trained solely on synthetic data, showed promising performance (e.g., validation MSE down to 0.0015 for directional filtering) and improved the detectability of faint signals, like bicycles among heavy vehicles, when applied to real DAS measurements from the test site. This framework uniquely integrates detailed traffic modeling with DAS physics, providing a novel tool to develop and evaluate DAS signal processing techniques, optimize cable layout deployments, and advance DAS applications in complex transportation monitoring scenarios. Creating such a procedure offers significant potential for advancing the application of DAS in transportation monitoring and smart city initiatives.
Open Access
A hybrid technique for mutual coupling reduction in a compact dual-band millimeter-wave MIMO antenna
(IEEE, 2025-07-01) Ahmad, Jawad; Hashmi, Mohammad; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This letter reports a hybrid approach employing metallic vias and metasurface for mutual coupling reduction in a MIMO antenna at mmWave frequencies. Initially, a dual-band coaxial-fed antenna, operating at 27 GHz and 28 GHz, is designed using modified K-shaped patch arms with a tapered profile which is then used to develop a four-element dual-band MIMO array. Subsequently, metallic vias are incorporated to suppress surface wave-induced coupling. Finally, metasurface slab is integrated to mitigate near-field interactions. The proposed design achieves an impedance bandwidth of 26.75-27.28 GHz and 27.77-28.19 GHz, with coupling levels below 30 dB, and broadside radiation patterns with respective peak gains of 6.52 dBi and 6.74 dBi. Furthermore, the proposed design exhibits an envelope correlation coefficient (ECC) of less than 0.05 for isotropic and less than 0.25 for Gaussian environments. An excellent agreement between the experimental and simulation results validate the proposed design approach.
Open Access
Cladding influence on the milling of low-stiffness aluminum alloy parts with local clamping
(Publicaciones DYNA, 2025-03-01) Casuso, Mikel; Rubio Mateos, Antonio; Silveira-Fernández, Elena; Veiga Suárez, Fernando; Lamikiz, Aitzol; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
The milling of aeronautical skins on flexible and reconfigurable fixtures is a major industrial challenge due both to the low rigidity of the skins and to the configuration of these fixtures, which, although they provide a great versatility of use and are an efficient alternative to pollutant chemical milling, vibrations can easily occur in them that may impair the surface quality, increase the error of the final thickness and cause excessive cutting forces. Aiming to foster the use of flexible fixtures, a study of the natural frequencies and cutting forces obtained when milling thin parts has been carried out, with special emphasis on analyzing the influence of the cladding of aluminum alloy parts.
Open Access
Modeling and optimal sizing of thyristor rectifiers for high-power hydrogen electrolyzers
(IEEE, 2025-05-01) Iribarren Zabalegui, Álvaro; Barrios Rípodas, Ernesto; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Thyristor rectifiers are currently the most common solution for supplying high-power electrolyzers. These rectifiers typically include a dc inductance, which significantly increases system costs. However, this inductance can be avoided by relying solely on ac-side inductances, required for grid current harmonic filtering, although this approach introduces specific challenges. Traditional analytical models of thyristor rectifiers are unable to determine the electrolyzer operating point for a given firing angle and may lead to incorrect system sizing, ultimately preventing the converter from delivering nominal power. This limitation arises from the fact that existing models are formulated for inductive or constant-current loads, whereas electrolyzers exhibit electrical behavior closer to constant-voltage loads. In this paper, a novel analytical model of 6- and 12-pulse thyristor rectifiers with constant-voltage load is developed. The model enables the analysis and optimal sizing of thyristor rectifiers directly connected to electrolyzers without a dc-side inductance. Its accuracy has been validated through both simulations and experimentally using a laboratory-scale prototype. Furthermore, the model has been applied to optimally size a 12-pulse rectifier supplying a 5.5 MW electrolyzer, demonstrating its suitability for the design of thyristor rectifier systems in industrial-scale electrolysis applications and highlighting its advantages over traditional approaches.
Open Access
Comparación de pacientes reales y estandarizados en el Grado de Medicina: un estudio de intervención aleatorizado y controlado
(Elsevier, 2025-06-01) Díez, Nieves; Franchez, B.; Rodríguez Díez, María Cristina; Vidaurreta, Marta; Betés, Maite Teresa; Fernández, Secundino; Palacio, P.; Pueyo, Francisco Javier Olivera; Martín Calvo, Nerea; Ciencias de la Salud; Osasun Zientziak; Institute of Smart Cities - ISC
Introducción: Los escenarios clínicos simulados permiten a los estudiantes aprender en un entorno seguro. Aunque se recomienda la participación de pacientes estandarizados (PE) en estos escenarios, existen pocos estudios que comparen el impacto en la educación médica entre PE y pacientes reales (PR). Métodos: Se seleccionaron 40 estudiantes de medicina por curso (4.º, 5.º y 6.º) y se asignaron aleatoriamente (1:1) a dos grupos: escenario con PR o con PE. Los estudiantes y el observador externo desconocían el tipo de paciente que participaba en el escenario. Los estudiantes completaron cuestionarios de sensaciones y conocimientos, y los profesores responsables y el observador externo, cuestionarios de sensaciones. La información cualitativa se recogió mediante grupos focales con los estudiantes. Resultados: No se encontraron diferencias significativas entre ambos grupos en las sensaciones percibidas ni en los conocimientos adquiridos, pero sí en la probabilidad de identificar correctamente el tipo de paciente (p < 0,001). La mayoría de los estudiantes del escenario con PE lo identificaron como PR. Tampoco se encontraron diferencias entre grupos, en los cuestionarios completados por profesores y observador externo. Los estudiantes se preparan e involucran más si creen estar ante un PR y consideran que el feedback del paciente es enriquecedor, independientemente del tipo de paciente. Conclusiones: Los estudiantes de medicina no diferencian a los PE de los PR en los escenarios, y los evalúan de manera similar. Ante la dificultad de disponer de PR con diversas patologías y niveles de gravedad, el PE es una buena alternativa para la formación de los estudiantes de medicina.
Open Access
Single-pixel compressive terahertz 3D imaging
(IEEE, 2025-04-24) Ndagijimana, Adolphe; Ederra Urzainqui, Íñigo; Heredia Conde, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Terahertz (THz) imaging contends with the lack of cost-effective, off-the-shelf high-resolution array detectors and the slow acquisition speeds associated with pixel-by-pixel raster scanning. Single-pixel imaging with Compressive Sensing (CS) represents a potential solution for resolution and acquisition speed in a cost-efficient manner. Our paper introduces a novel approach for extending 2D single-pixel THz imaging systems to 3D using a single frequency. By leveraging the single-pixel approach, we achieve 3D resolution while avoiding mechanical scanning, and the use of a single frequency eliminates the need for bandwidth, a significant limitation of conventional techniques, where design of THz sources and detectors with large bandwidth remains challenging and typically complex. The Order Recursive Matching Pursuit (ORMP) algorithm is used as the sparse recovery method to exploit the sparsity/compressibility of the 3D THz signal and enable sampling at a rate far lower than that required by the Nyquist Theorem. The 2D sensing matrix is obtained by analyzing the diffracted propagation of THz imaging systems on a 2D surface perpendicular to the optical axis. Moreover, the 3D sensing matrix is based on the diffracted propagation of 2D surfaces at different sampling depth positions. Our system can quickly capture the reflective properties of every point in a 3D space using a single-pixel camera setup that leverages CS, making it a simple and efficient method for creating a fast 3D THz imaging system, particularly suited to high-frequency THz sources that operate efficiently at a single frequency or at small bandwidth.
Open Access
Cavity-stacked filter in CLAF-SIW technology for millimeter waves
(Elsevier, 2025-03-01) Segura-Gómez, Cleofás; Biedma-Pérez, Andrés; Santiago Arriazu, David; Palomares-Caballero, Ángel; Arregui Padilla, Iván; Gómez Laso, Miguel Ángel; Padilla, Pablo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This work presents the design of a cavity-stacked bandpass filter (BPF) using contactless air-filled substrate integrated waveguide (CLAF-SIW) technology for millimeter-wave frequencies. This technology is a variant of air-filled SIW technology, incorporating contactless techniques. It enables the reduction of dielectric losses in SIW filters while supporting multilayer structures with robust assembly. The cavity-stacked filter topology allows for very good frequency responses with a reduced footprint and no transitions needed. As an example, a 4th-order Chebyshev bandpass filter composed of four stacked cavities, coupled through irises, is shown. The iris layers are fabricated by metallizing the slot edges of a PCB, while the cavity layers are implemented using CLAF-SIW. The filter has been designed and manufactured to provide a passband response from 36 GHz to 37.5 GHz. A good agreement between measurement and simulation has been achieved. The losses in the proposed CLAF-SIW filter are primarily due to the metal roughness of the low-cost commercial laminates used.