Artículos de revista DIEC - IEKS Aldizkari artikuluak

Permanent URI for this collection

http://hdl.handle.net/2454/29500

Browse

Now showing 1 - 20 of 572

Open Access
Techno-economic assessment of MW-scale solid oxide electrolysis hydrogen production plant: integrating possibilities in Spain
(Elsevier, 2024-12-22) Jiménez-Martín, Gonzalo; Judez, Xabier; Aguado Alonso, Mónica; Garbayo, Iñigo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Gobierno de Navarra / Nafarroako Gobernua
Solid oxide electrolysis (SOE) is regarded as the most efficient green hydrogen production technology. However, the cost competitiveness of this technology for large-scale hydrogen production is at stake due to the complexity of operating at high temperatures. This study aims to estimate the levelized cost of hydrogen (LCOH) of a MWscale SOE system and its possible integration in Spain. The heat exchanger network of a SOE system has been optimized by a pinch analysis and the techno-economic feasibility of the system has been assessed. Even if initial LCOH estimations of >6 €⋅kg− 1 are obtained with the electricity and stack costs as the major contributors, optimistic scenarios indicate that LCOH can be reduced below 4 €⋅kg− 1 , or even further by coupling the systems to heat-intensive industries such as Spanish cement or steel factories.
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
Photonic chip breath analyzer
(SpringerOpen, 2025-06-03) Gallego Martínez, Elieser Ernesto; Matías Maestro, Ignacio; Ruiz Zamarreño, Carlos; 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 introduces a novel single-package optical sensing device for multiple gas sensing, which is suitable for breath analysis applications. It is fabricated on a coverslip substrate via a sputtering technique and uses a planar waveguide configuration with lateral incidence of light. It features three sequentially ordered strips of different materials, which serve to increase the multivariate nature of the response of the device to different gases. For the proof-of-concept, the selected materials are indium tin oxide (ITO), tin oxide (SnO2), and chromium oxide III (Cr2O3), while the selected gases are nitric oxide (NO), acetylene (C2H2), and ammonia (NH3). The sensing mechanism is based on the hyperbolic mode resonance (HMR) effect, with the first-order resonance obtained for each strip located in the near infrared region. The multivariate response of the resonances and the correlation with the concentration of each gas allow training a machine learning (ML) model based on a nonlinear autoregressive neural network, enabling the accurate prediction of the concentration of each gas. The obtained limit of detection for all the gases was in the order of a few parts per billion. This innovative approach coined as the multivariate optical resonances spectroscopy demonstrates the potential of HMR-based optical sensors in combination with ML techniques for ultra-sensitive multi-gas detection applications using a single device.
Open Access
Formalize clinical processes into electronic health information systems: modelling a screening service for diabetic retinopathy
(Elsevier, 2015-06-14) Eguzkitza Diego, Aitor; Trigo Vilaseca, Jesús Daniel; Martínez de Espronceda Cámara, Miguel; Serrano Arriezu, Luis Javier; Andonegui Navarro, José; Ciencias de la Salud; Osasun Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Most healthcare services use information and communication technologies to reduce and redistribute the workload associated with follow-up of chronic conditions. However, the lack of normalization of the information handled in and exchanged between such services hinders the scalability and extendibility. The use of medical standards for modelling and exchanging information, especially dual-model based approaches, can enhance the features of screening services. Hence, the approach of this paper is twofold. First, this article presents a generic methodology to model patient-centered clinical processes. Second, a proof of concept of the proposed methodology was conducted within the diabetic retinopathy (DR) screening service of the Health Service of Navarre (Spain) in compliance with a specific dual-model norm (openEHR). As a result, a set of elements required for deploying a model-driven DR screening service has been established, namely: clinical concepts, archetypes, termsets, templates, guideline definition rules, and user interface definitions. This model fosters reusability, because those elements are available to be downloaded and integrated in any healthcare service, and interoperability, since from then on such services can share information seamlessly.
Open Access
EMG filling analysis, a new method for the assessment of recruitment of motor units with needle EMG
(Elsevier, 2025-02-20) Mariscal Aguilar, Cristina; Navallas Irujo, Javier; Malanda Trigueros, Armando; Recalde Villamayor, Silvia; Rodríguez Falces, Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Objectives: The progression of recruitment of motor unit potentials (MUPs) during increasing voluntary contraction can provide important information about the motor units (MUs) innervating a muscle. Here, we described a method to quantitate the recruitment level of the intramuscular electromyographic (iEMG) signal during an increasing force level. Methods: Concentric needle EMG signals were recorded from the tibialis anterior of healthy subjects as force was gradually increased from 0 to maximum force. The iEMG filling process was analyzed by measuring the EMG filling factor (FF), calculated from the mean rectified iEMG and the root mean square iEMG. Results: (1) The iEMG activity at low contraction forces was “discrete” (FF<0.3) for all participants. (2) The iEMG activity at maximal effort was “full” (FF>0.5) for 83 % of the participants, whereas it was “incompletely-reduced” (0.3
Open Access
Effects of time-restricted eating and resistance training on skeletal muscle tissue quantity, quality and function in postmenopausal women with overweight or obesity: a study protocol
(Elsevier, 2024-12-30) Alfaro-Magallanes, Víctor Manuel; Medrano Echeverría, María; Echarte Medina, Jon; Osés Recalde, Maddi; Izquierdo Rodríguez, Claudia; Concepción Álvarez, Mara de la Caridad; Galbete Jiménez, Arkaitz; Idoate, Fernando; Zugasti Murillo, Ana; Petrina Jáuregui, María Estrella; Goñi Gironés, María Elena; Ribelles, María Jesús; Amasene, María; Arenaza Etxeberría, Lide; Tejada Garrido, Clara Isabel; Elejalde, E.; Azcárate Jiménez, Unai Xabier; Ruiz Sarrias, Oskitz; Sayar-Beristain, Onintza; García-Ramos, Amador; Martínez Labari, Cristina; Armendáriz Brugos, Cristina; Villanueva Larre, Arantxa; Ruiz Ruiz, Jonatan; Cabeza Laguna, Rafael; Labayen Goñi, Idoia; Ciencias de la Salud; Osasun Zientziak; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
Background & aims: time-restricted eating (TRE) shows promise for weight loss and improving menopauserelated body composition and cardiometabolic health, but its effects on skeletal muscle tissue (SMT) in postmenopausal women are unknown. This study investigates the effects of three weight loss interventions over 12 weeks on SMT quantity, quality, function, and cardiometabolic health in postmenopausal women with overweight/obesity, with effects persistence evaluated at a 12-month follow-up. Methods and results: in this randomized controlled trial, 78 postmenopausal women (50–65 years; BMI 25–40 kg/m2; sedentary lifestyle; eating window ≥12 h/day; no severe metabolic impairments) will be recruited. Participants will be randomly assigned to one of three groups for 12 weeks: TRE, TRE + resistance training, or CR + resistance training. The TRE groups will reduce their eating window to 8 h and receive nutritional advice to adhere to a Mediterranean diet. The CR group will follow a personalized hypocaloric diet (− 500 kcal/day). Resistance training groups will perform supervised resistance training 3 times/week. Primary Outcome: Change in SMT quantity measured by MRI at baseline and after 12 weeks. Secondary Outcomes: intermuscular adipose tissue (IMAT), strength, power, body weight and composition, and cardiometabolic risk factors. Conclusion: this study will illustrate the effects of TRE and TRE combined with resistance exercise compared with the currently recommended obesity-lifestyle treatment on SMT quantity, quality, function, and cardiometabolic markers. The results will offer insights into dietary strategies to combat obesity and metabolic diseases without increasing sarcopenia risk in postmenopausal women, a sparsely studied and particularly affected population.
Open Access
Experimental demonstration of the impact of the fringe shape in sub-lambda/2 sensing with optical feedback interferometry
(Optica Publishing Group, 2020-12-22) Knudsen, Einar; Perchoux, Julien; Mazoyer, Thierry; Imas González, José Javier; Veng, Mengkoung; Jayat, Francis; Tronche, Clément; Bosch, Thierry; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
It is established in the optical feedback interferometry (OFI) theory that the shape of the interferometric fringe has an impact on the detector's response to very small displacement measurements. In this paper, we validate¿for the first time, to the best of our knowledge, based on experimental results¿this statement by comparing experiments to an established model implementation. Through these experiments, we show that the amplitude of the signals induced by sub-lambda/2 optical path variations is linearly dependent on the slope of the underlying fringe. Thus, careful control of the phase allows us to maximize the detection amplitude of very small displacements by positioning the phase where the fringe slope is the steepest. These results are directly applicable to established OFI applications that measure sub-lambda/2 optical path variations, such as OFI vibrometers or acoustic imaging though the acousto-optic effect.
Open Access
Demonstration of pressure wave observation by acousto-optic sensing using a self-mixing interferometer
(MDPI, 2023-04-04) Maqueda, Sébastien; Perchoux, Julien; Tronche, Clément; Imas González, José Javier; Genetier, Marc; Lavayssière, Maylis; Barbarin, Yohan; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
In this paper, we demonstrate that a compact and inexpensive interferometric sensor based on the self-mixing effect in the laser cavity can be used for the characterization of shock waves. The sensor measures the changes in the refractive index induced by the shock wave. It is based on the self-mixing interferometry scheme. We describe the architecture of the dynamic sensor and the design of the experimental setup used for the characterization that involves a shock tube. Thus, we detail the experimental measurements for shock wave pressure amplitude of 5 bar and address their interpretation with regard to the most admitted models for acousto-optics.
Open Access
Lossy mode resonances generated in planar configuration for two-parameter sensing
(IEEE, 2021-04-29) Fuentes Lorenzo, Omar; Corres Sanz, Jesús María; Domínguez Rodríguez, Ismel; Del Villar, Ignacio; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This work shows a new sensor structure for simultaneous measurement of two parameters, temperature and refractive index. The optical configuration consists of incidence of light on the edge of a soda-lime coverslip fully coated with a CuO thin film and partially coated with a PDMS thick layer. This planar configuration permitted to generate two separated lossy mode resonances (LMRs): one centered at 600 nm and the other at 1000 nm. The second resonance is induced by the PDMS layer and it can be used to measure the temperature due to its high thermo-optic coefficient (the sensitivity is -1.75 nm/°C in the temperature range from 20 to 40 °C), whereas the first resonance is used for sensing refractive index with sensitivity of 1460 nm/RIU in the refractive index range from 1.3328 and 1.37. Finally, a calibration test was carried out using a calibrated oil series with refractive index ranging from 1.33 to 1.36. This work demonstrates the possibility of generating multiples resonances in a single structure as simple as a coverslip, which can be used as a multi-parameter interchangeable sensor, especially suitable for biological applications or the detection of heavy metals in water.
Open Access
Complications related to the securement device in peripheral intravenous catheters: a randomized study
(Lippincott Williams and Wilkins, 2024) Ferraz Torres, Marta; Sancho Sena, Elena; Corcuera Martínez, María Inés; Martínez-García, Óscar; Suárez Mier, María Belén; Ciencias de la Salud; Osasun Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
Studies have not demonstrated the effectiveness of the different types of dressings in reducing the rate of complications. The purpose of this study was to determine which type of dressing is most beneficial in reducing the rate of complications. A total of 281 patients requiring a peripheral intravenous catheter were randomized to receive partially reinforced dressings or fully reinforced dressings (dressings with integral catheter securement). Patients were followed throughout their entire catheter course, and complications included infection, occlusion, phlebitis, accidental dislodgement, extravasation, and medical adhesive-related skin injury. Catheter outcome data were compared to determine whether statistically significant differences existed between the 2 groups. The groups had equivalent demographic characteristics and catheter indications. The average securement time with partially reinforced dressings was 2.72 days, and that for fully reinforced dressings was 2.64 days. However, catheters secured with fully reinforced dressings were associated with fewer total complications, such as infectious phlebitis (P = .043) and accidental dislodgement (P = .03). The fully reinforced securement device significantly reduced the rate of complications related to accidental dislodgement of the device and cases of infectious phlebitis. The use of fully reinforced dressings could reduce catheter-associated complications and improve the quality of patient care.
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
A design proposal using coherently radiating periodic structures (CORPSs) for 2-D phased arrays of limited scanning
(MDPI, 2024-09-18) Calvillo, Gilberto; Panduro, Marco A.; Juárez, Elizvan; Reyna, Alberto; Río Bocio, Carlos del; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
New configurations of 2-D phased arrays are proposed in this paper for reducing the number of phase shifters. This design methodology is based on the use of a novel coherently radiating periodic structures (CORPSs) block for 2-D phased arrays. Two new antenna systems for 2-D phased arrays are studied and analyzed utilizing the CORPSs blocks of four inputs and nine outputs. These CORPSs feeding blocks are applied in a smart way to feed the planar antenna arrays by generating the required phase plane and reducing the number of control ports. Interesting results are provided based on the experimental measurements and full-wave simulations. These results illustrate a great reduction of the active devices (phase shifters), providing a good design compromise in terms of the scanning range and side lobe level performance. Furthermore, the provided results illustrate a maximum reduction capability in the number of phase shifters of 81%, considering a scanning range of ±30° in azimuth and ±30° in elevation. A raised cosine distribution is applied to reach side lobe levels of −19 dB for ±18° and −17 dB for ±30° in elevation. These benefits could be of interest to designers of phased antenna systems.
Open Access
On the lossy character of Y-branches and their analogy to Wilkinson power dividers
(Optica Publishing Group, 2024-11-04) Oña Valladares, Douglas; Hernández Martínez, Osmery; Ortega Gómez, Ángel; González-Andrade, David; Liberal Olleta, Íñigo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Y-branches are commonly used devices for power splitting and combining in various technological applications. Despite their widespread use, research on their design and analysis has been mostly focused on their characterization based on reflection and transmission when operating as power dividers, leaving aside an exhaustive consideration of all their possible modes of operation. Also, it has not been fully recognized that these devices have intrinsic losses. If these losses are not properly managed, they can negatively impact the network, but also open the door to new opportunities. In this context, this paper examines Y-bifurcation properties and their connection to Wilkinson's power dividers. Additionally, through numerical analysis, we demonstrate the possibility of integrating these devices into more complex optical networks. We use them as components in generalized power dividers and analog optical computational systems designed to filter out the maximum common phase component and avoid backward reflections for any input signal.
Open Access
The probability density function of the surface electromyogram and its dependence on contraction force in the vastus lateralis
(BMC, 2024-10-26) Rodríguez Falces, Javier; Malanda Trigueros, Armando; Mariscal Aguilar, Cristina; Recalde Villamayor, Silvia; Navallas Irujo, Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Introduction: the probability density function (PDF) of the surface electromyogram (sEMG) depends on contraction force. This dependence, however, has so far been investigated by having the subject generate force at a few fixed percentages of MVC. Here, we examined how the shape of the sEMG PDF changes with contraction force when this force was gradually increased from zero. Methods: voluntary surface EMG signals were recorded from the vastus lateralis of healthy subjects as force was increased in a continuous manner vs. in a step-wise fashion. The sEMG filling process was examined by measuring the EMG filling factor, computed from the non-central moments of the rectified sEMG signal. Results: in 84% of the subjects, as contraction force increased from 0 to 10% MVC, the sEMG PDF shape oscillated back and forth between the semi-degenerate and the Gaussian distribution; the PDF–force relation varied greatly among subjects for forces between 0 and ~ 10% MVC, but this variability was largely reduced for forces above 10% MVC; the pooled analysis showed that, as contraction force gradually increased, the sEMG PDF evolved rapidly from the semi-degenerate towards the Laplacian distribution from 0 to 5% MVC, and then more slowly from the Laplacian towards the Gaussian distribution for higher forces. Conclusions: the study demonstrated that the dependence of the sEMG PDF shape on contraction force can only be reliably assessed by gradually increasing force from zero, and not by performing a few constant-force contractions. The study also showed that the PDF–force relation differed greatly among individuals for contraction forces below 10% MVC, but this variability was largely reduced when force increased above 10% MVC.
Open Access
Quantum and thermal noise in coupled non-hermitian waveguide systems with different models of gain and loss
(De Gruyter, 2025-01-03) Hernández Martínez, Osmery; Liberal Olleta, Íñigo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Non-Hermitian (NH) photonic systems leverage gain and loss to open new directions for nanophotonic technologies. However, the quantum and thermal noise intrinsically associated with gain/loss affects the eigenvalue/eigenvector structure of NH systems, and thus the existence of exceptional points, as well as the practical noise performance of these systems. Here, we present a comparative analysis of the impact of different gain and loss mechanisms on the noise generated in gain-loss compensated NH waveguide systems. Our results highlight important differences in the eigenvalue/eigenvector structure, noise power, photon statistics and squeezing. At the same time, we identify some universal properties such as the occurrence of phase-transition points in parameter space and intriguing phenomena related to them, including coalescence of pairs of eigenvectors, gain-loss compensation, and linear scaling of the noise with the length of the waveguide. We believe that these results contribute to a better understanding of the impact of the gain/loss mechanism on the noise generated in NH systems.
Open Access
Spatiotemporal symmetries and energy-momentum conservation in uniform spacetime metamaterials
(American Chemical Society, 2024-11-13) Liberal Olleta, Íñigo; Ganfornina Andrades, Antonio; 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
Spacetime metamaterials are opening new regimes of light-matter interactions based on the breaking of temporal and spatial symmetries, as well as intriguing concepts associated with synthetic motion. In this work, we investigate the continuous spatiotemporal translation symmetry of spacetime metamaterials with uniform modulation velocity. Using Noether's theorem, we demonstrate that such symmetry entails the conservation of the energy momentum. We highlight how energy-momentum conservation imposes constraints on the range of allowed light-matter interactions within spacetime metamaterials, as illustrated with examples of the collision of electromagnetic and modulation pulses. Furthermore, we discuss the similarities and differences between the conservation of energy-momentum and relativistic effects. We believe that our work provides a step forward in clarifying the fundamental theory underlying spacetime metamaterials.
Open Access
Distributed vibration sensing based on optical vector network analysis
(IEEE, 2024-10-28) Loayssa Lara, Alayn; Vallifuoco, Raffaele; Zahoor, Rizwan; Zeni, Luigi; Sagüés García, Mikel; Minardo, Aldo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We introduce a novel method for distributed vibration sensing based on extracting the time-domain Rayleigh impulse response of an optical fiber from optical vector network analysis measurements. The optical-frequency-domain transfer function of the fiber is first measured, and then inverse Fourier transformed to provide the bandpass optical time-domain impulse response. Another relevant feature of the technique is that it enables excitation demodulation using the optical frequency dependence of the Rayleigh backscatter signal from the optical fiber, the so-called Rayleigh signature. This is the simplest method to obtain fully linear quantitative measurements of local changes in the strain or temperature experienced by the fiber and it is inherently free from signal fading impairments. Furthermore, the implementation of the technique uses a simple setup based on double-sideband modulation of a laser, self-homodyne detection with an optical hybrid, and narrow-bandwidth electrical signal acquisition and processing. We present proof-of-concept experiments to demonstrate the operation of the method with the measurement of dynamic strain and temperature perturbations in a 115-m optical sensing fiber with 16-cm spatial resolution and a sensitivity of 59 nHz. This sensing technique has the potential to provide high-sensitivity distributed measurements of tens-of-hertz excitations in hundreds-of-meters fibers, with centimeter spatial resolution. Therefore, it can become a valuable tool for structural health monitoring in application fields such as aerospace, marine, or civil engineering.
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.
Embargo
Effects of early, late and self-selected time-restricted eating on visceral adipose tissue and cardiometabolic health in participants with overweight or obesity: a randomized controlled trial
(Nature Research, 2025-01-07) Dote-Montero, Manuel; Clavero-Jimeno, Antonio; Merchán Ramírez, Elisa; Osés Recalde, Maddi; Echarte Medina, Jon; Camacho-Cardenosa, Alba; Concepción Álvarez, Mara de la Caridad; Amaro Gahete, Francisco J.; Alcántara Alcántara, Juan Manuel; López-Vázquez, Alejandro; Cupeiro, Rocío; Migueles, Jairo H.; De la O, Alejandro; García Pérez, Patricia Virginia; Contreras-Bolivar, Victoria ; Muñoz-Garach, Araceli; Zugasti Murillo, Ana; Petrina Jáuregui, María Estrella; Álvarez de Eulate, Natalia; Goñi Gironés, María Elena; Armendáriz Brugos, Cristina; González Cejudo, María Trinidad; Martín-Rodríguez, José L.; Idoate, Fernando; Cabeza Laguna, Rafael; Carneiro-Barrera, Almudena; Cabo, Rafael de; Muñoz Torres, Manuel; Labayen Goñi, Idoia; Ruiz, Jonatan R.; Ciencias de la Salud; Osasun Zientziak; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
The optimal eating window for time-restricted eating (TRE) remains unclear, particularly its impact on visceral adipose tissue (VAT), which is associated with cardiometabolic morbidity and mortality. We investigated the effects of three TRE schedules (8 h windows in the early day, late day and participant-chosen times) combined with usual care (UC, based on education about the Mediterranean diet) versus UC alone over 12 weeks in adults with overweight or obesity. The primary outcome was VAT changes measured by magnetic resonance imaging. A total of 197 participants were randomized to UC (n = 49), early TRE (n = 49), late TRE (n = 52) or self-selected TRE (n = 47). No significant differences were found in VAT changes between early TRE (mean difference (MD): −4%; 95% confidence interval (CI), −12 to 4; P = 0.87), late TRE (MD: −6%; 95% CI, −13 to 2; P = 0.31) and self-selected TRE (MD: −3%; 95% CI, −11 to 5; P ≥ 0.99) compared with UC, nor among the TRE groups (all P ≥ 0.99). No serious adverse events occurred; five participants reported mild adverse events. Adherence was high (85–88%) across TRE groups. These findings suggest that adding TRE, irrespective of eating window timing, offers no additional benefit over a Mediterranean diet alone in reducing VAT. TRE appears to be a safe, well-tolerated and feasible dietary approach for adults with overweight or obesity. ClinicalTrials.gov registration: NCT05310721.
Open Access
Methodology for comparative assessment of battery technologies: experimental design, modeling, performance indicators and validation with four technologies
(Elsevier, 2025-01-15) Irujo Izcue, Elisa; Berrueta Irigoyen, Alberto; 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, PJUPNA2023-11380; Gobierno de Navarra / Nafarroako Gobernua
An increasing number of applications with diverse requirements incorporate various battery technologies. Selecting the most suitable battery technology becomes a tedious task as several aspects need to be taken into account. Two of the key aspects are the battery characteristics under temperature variations and their degradation. While numerous contributions using tailored assessment methods to evaluate both aspects for a particular application exist in the literature, a general methodology for analysis is necessary to enable a quantitative comparison between different technologies. We propose in this paper a novel methodology, based on performance indicators, to quantify the potential and limitations of a battery technology for diverse applications sharing a similar operational profile. A quantification of phenomena such as the influence of high and low temperatures on the battery, or the effect of cycling and state of charge on battery aging is obtained. In pursuit of these indicators, an experimental procedure and the fitting of aging model parameters that allow their calculation are proposed. As an additional outcome of this work, a general aging model that allows comprehensive analysis of aging behavior is developed and the trade-off between experimental time and accuracy is analyzed to find an optimal experimental time between 2 and 4 months, depending on the studied battery technology. Finally, the proposed methodology is applied to four battery technologies in order to show its potential in a real case-study.

Browse

Recent Submissions