Artículos de revista ISC - ISC aldizkari artikuluak

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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.
Open Access
A 3-D-printing-oriented coaxial-line filter with wide out-of-band rejection
(IEEE, 2025-06-18) Baranowski, Michal; Pons Abenza, Alejandro; Arregui Padilla, Iván; Lopetegui Beregaña, José María; Álvarez Botero, Germán Andrés; Lamecki, Adam; Gómez Laso, Miguel Ángel; Martín Iglesias, Petronilo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
In this letter, a novel design for a 3-D-printed, self-supported coaxial-line X-band filter is presented. The filter is intended for Earth observation (EO) data downlink systems, where it must effectively reject signals in a wide frequency range. The filter design incorporates a 15th-order low-pass filter structure with a smooth profile, integrated with a short bandpass section with four $\lambda /4$ short-circuited stubs. The optimization of the low-pass section is attained by means of shape deformation, including the inner and outer coaxial conductors, and leads to a wide rejection band up to around 40 GHz, to suppress the third harmonic and other undesired out-of-band frequencies. A prototype was fabricated in one piece in an aluminum alloy using selective laser melting (SLM) and measured, exhibiting excellent agreement with simulations. In terms of out-of-band performance, the proposed coaxial-line filter is superior to other related state-of-the-art solutions.
Open Access
Experimental investigation of a R290 domestic heat pump equipped with a thermoelectric-aided sub-cooler
(Elservier, 2025-06-01) Pendzialek, M.; Özyildiz, Tufan; Fingas, Rafal; Sánchez, Daniel; Aranguren Garacochea, Patricia; Smolka, Jacek; Haida, Michal; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
The energy efficiency of heat pumps is an important factor for the sustainability and electrification of domestic heating, especially for the most common air-to-water heat pumps, which are a competitive solution to conventional heating methods. However, novel solutions for cold and moderate climate zones must be developed considering environmentally friendly natural refrigerants such as hydrocarbons. One idea is to introduce a thermoelectric-aided sub-cooler into an air-to-water heat pump to improve the coefficient of performance. Therefore, this work aims to experimentally investigate a novel propane heat pump system with a prototype thermoelectric-aided sub-cooler for domestic heating. Energy analysis was performed to evaluate the energy impact of the sub-cooler in terms of ambient conditions from -10.0 ºC to 5.0 ºC, different water temperatures for heating applications in existing buildings from 45.0 ºC to 55.0 ºC and varying operating conditions of thermoelectric modules in the sub-cooler. The performance of the sub-cooler was evaluated. The results confirm that introducing a thermoelectric-aided sub-cooler can improve the heat pump performance by up to 6.0% and the heating capacity improvement by up to 17.0% for the low ambient temperature of -10.0 ºC. Furthermore, an optimal direct current voltage below 3.0 V was found for every investigated operating condition to ensure the best system coefficient of performance.
Open Access
Multi antenna structure assisted by metasurface concept providing circular polarization for 5G millimeter wave applications
(Nature, 2025-05-21) Althuwayb, Ayman Abdulhadi; Ali, Esraa Mousa; Alibakhshikenari, Mohammad; Virdee, Bal S.; Rashid, Nasr; Kaaniche, Khaled; Atitallah, Ahmed Ben; Elhamrawy, Osama I.; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This paper presents a circularly polarized multi-antenna structure designed for 5G millimeter-wave applications. The structure is based on circular patch radiators, each enhanced with metasurface (MTS) characteristics through the integration of multi-split ring slots. Each radiating element is enclosed within a decoupling wall constructed from a microstrip transmission line, which features both wide (capacitive) and thin (inductive) impedance profiles. The antennas are excited from below using metallic pins, which connect to the radiators through via-holes stemming from coplanar waveguide ports on the ground plane. Experimental results demonstrate a wide bandwidth from 25.6 to 29.7 GHz, corresponding to a fractional bandwidth of 14.82%. Additionally, the antenna exhibits stable radiation patterns, with an average gain of 2.7 dBi and a radiation efficiency of 57%. Using a single radiator configuration, a 3 × 3 antenna array was implemented. In this design, electromagnetic coupling between adjacent radiators is significantly reduced. The resulting array, measuring 20 × 20 × 0.32 mm3, achieves excellent performance across a wide frequency range from 24 to 31 GHz, corresponding to a bandwidth of 25.45%. Key metrics include an average isolation between radiating elements exceeding 17 dB and an average gain and radiation efficiency of 9.0 dBi and 91.5%, respectively.
Open Access
An efficient numerical method for 1D singularly perturbed parabolic convection-diffusion systems with repulsive interior turning points
(Elsevier, 2025-12-15) Clavero, Carmelo; Jorge Ulecia, Juan Carlos; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
In this work, we propose and study a numerical method to solve efficiently one-dimensional parabolic singularly perturbed systems of convection-diffusion type, for which the convection coefficient is zero at an interior point of the spatial domain. We focus our attention on the case of having the same diffusion parameter in both equations; as well we assume adequate signs on the convective coefficients in order to the interior turning point is of repulsive type. Under these conditions, if the data of the problem are composed by continuous functions, the exact evolutionary solution, in general, has regular boundary layers at the end points of the spatial domain. To solve this type of problems, we combine the fractional implicit Euler method and the classical upwind scheme, defined on a special mesh of Shishkin type. The resulting numerical method reach uniform convergence of first order in time and almost first order in space. Numerical results obtained for different test problems are shown which corroborate in practice the uniform convergence of the numerical algorithm and also their computational efficiency in comparison with classical numerical methods used for the same type of problems.
Open Access
Understanding the dynamics of crowdshipping in last-mile distribution within urban mobility: a comprehensive framework
(Elsevier, 2025-10-01) García Herrera, Alisson Maurinne; Serrano Hernández, Adrián; Faulín Fajardo, Javier; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Crowdshipping, a collaborative economy model that takes advantage of the crowd for the delivery of goods, promises to address the problems of urban logistics. This article integrates the literature to identify relevant factors that influence the success of crowdshipping, while addressing sustainability objectives. We use the PRISMA method, a widely recognized framework for systematic reviews that, by meeting high-quality standards, guarantees the reliability of the evidence. We systematically reviewed the literature to address three research questions: identifying factors that influence crowdshipping success, evaluating its contribution to sustainability goals, and evaluating the role of Operation Research (OR) in improving crowdshipping efficiency. Specifically, OR techniques offer significant potential for optimizing routing, matching supply and demand, and enhancing decision-making processes. Through this comprehensive and in-depth analysis, we provide information for future research, modeling, practical implementation, and potential policy recommendations.
Open Access
Systematic review of clinical practice guidelines for long-term breast cancer survivorship: assessment of quality and evidence-based recommendations
(Springer Nature, 2025-05-17) Pimentel Parra, Gustavo Adolfo; García Vivar, Cristina; Escalada Hernández, Paula; Santos Martín, José Luis; Soto Ruiz, María Nelia; Ciencias de la Salud; Osasun Zientziak; Institute of Smart Cities - ISC
BACKGROUND: Breast cancer is the most common cancer among women, with improved survival rates due to advances in early diagnosis and therapies. However, long-term survivors (≥5 years post-treatment, disease-free) face persistent physical, psychological, and social challenges requiring tailored, evidence-based care. Despite the growing survivor population, no systematic evaluation of Clinical Practice Guidelines (CPGs) for this group has been conducted. This study assesses the quality of CPGs and their evidence-based recommendations. METHODS: A systematic review was conducted in PubMed, CINAHL, and Cochrane Library (2015–2023), including guidelines from major oncology organisations. The AGREE II instrument evaluated CPG quality across six domains, and recommendations were classified using a Primary Care survivorship framework: prevention, surveillance, care coordination, and long-term effect management. RESULTS: Ten CPGs met inclusion criteria, with 7 classified as high quality. Most recommendations focused on prevention (adjuvant therapy, alcohol) and surveillance (follow-up, mammography), while gaps remained in lifestyle guidance, psychosocial support, and management of complications (lymphedema, osteoporosis, cognitive dysfunction). Care coordination and psychosocial interventions were inconsistently addressed. CONCLUSIONS: Current CPGs inadequately cover the complex needs of long-term survivors, particularly in psychosocial care. Evidence-based, patient-centred guidelines are urgently needed to optimise long-term outcomes and quality of life.
Open Access
Multivariable QFT control of the direction flip problem in wire arc additive manufacturing
(Wiley, 2025-04-25) Masenlle, Manuel; Elso Torralba, Jorge; Ostolaza, J. Xabier; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
Additive metal manufacturing (AM), particularly Wire Arc Additive Manufacturing (WAAM), offers a compelling alternative to traditional machining methods. While AM presents advantages such as reduced material waste and lower production costs, challenges remain in effectively controlling the process to prevent defects and optimise material deposition. This article proposes a multivariable control system for WAAM utilising Quantitative Feedback Theory (QFT) to maintain the shape of the heat-affected zone (HAZ) during transitions in direction flips during layer deposition. By modelling these direction flips as predictable disturbances, the full potential of QFT to integrate feedback and feedforward actions is exploited. The resulting multivariable control laws seek to minimise temperature variation in two critical points around the welding pool by adequately manipulating the power and speed of the heat source. A benchmark system is established to evaluate the effectiveness of the proposed control system. The results demonstrate significant improvement in temperature control, leading to enhanced layer construction quality and reduced need for height corrections or cooling pauses.
Open Access
Power converter for ultra low-frequency and low-voltage energy harvesters
(SpringerOpen, 2025-05-29) Hualde Otamendi, Mikel; Cruz Blas, Carlos Aristóteles de la; Castellano Aldave, Jesús Carlos; Carlosena García, Alfonso; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Energy conversion mechanisms present in some harvesters are only able to provide very low voltage (mV) and fre‑ quency (few Hz) electrical signals, which may also have a bipolar nature (AC). These characteristics make unusable most conventional power converters to extract from them a DC voltage. This letter describes an autonomous selfstarting ultra-low voltage and frequency AC-DC converter that can start the operation for AC signals around 25 mV, and below 10 Hz. The converter has been designed with ultra-low vibration harvesters in mind, but is also of appli‑ cation to, for instance, thermoelectric generators (TEG). The circuit is basically an oscillator driven by the harvester output, which therefore converts a low-frequency and low-voltage signal into large signal oscillation amenable for further DC conversion. The proposed circuit is based on the classical Hartley oscillator, which is modifed in a non‑ trivial confguration, and optimized to be able to operate with bipolar, low frequency and voltage driving signals. This is achieved with a minimum number of passive components and a single JFET transistor. A practical prototype has been fabricated, and measurement results are obtained, demonstrating the feasibility of the approach. Moreover, a vibration harvester with the power converter proposed has been tested in real conditions in a wind turbine.
Open Access
Augmented reality for intramuscular injection training: a cluster randomized controlled trial
(Elsevier, 2025-07-01) Soto Ruiz, María Nelia; Escalada Hernández, Paula; Bujanda Sainz de Murieta, Arantxa; Ballesteros Egüés, Tomás; Larráyoz Jiménez, Ana; San Martín Rodríguez, Leticia; Ciencias de la Salud; Osasun Zientziak; Institute of Smart Cities - ISC
Background: The acquisition of clinical skills, such as intramuscular injection, is crucial in nursing education, traditionally taught through theory and practice. Recent studies suggest that augmented reality (AR) enhances students' learning. Aim: To evaluate the effect of an augmented reality application (ARSim2care) for training intramuscular injections technique among undergraduate nursing students. Methods: A cluster randomized controlled trial was conducted. A total of 72 nursing students participated in the study (32 in the intervention group and 40 in the control group). Sociodemographic variables and dependent variables such as knowledge, skills, satisfaction and self-confidence with learning were measured. Results: The groups showed statistically significant differences in age. Knowledge acquisition in the intervention group was 0.56 points higher, this difference was statistically significant. No significant differences were found in technical skills, satisfaction and self-confidence although both groups showed positive results. Conclusions: The ARSim2care application enhanced nursing students' theoretical knowledge of intramuscular injections, although no significant improvements in technical skills were observed. Augmented reality shows potential as an educational tool; however, further research is required to evaluate its long-term effectiveness.
Open Access
Multidirectional bending sensor using capillary fibers and machine learning for real-time applications
(IEEE, 2025-02-25) Vanegas Tenezaca, Evelyn Dayanara; Galarza Galarza, Marko; Dauliat, Romain; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Publica de Navarra / Nafarroako Unibertsitate Publikoa
In this article, the design and implementation of a bidirectional curvature sensor based on a fiber-optic interferometer are presented. The sensor structure was fabricated by fusing a capillary fiber fragment between single-mode fibers (SMFs), with the addition of a long end capillary to promote a long interferometric section, forming a Fabry-Perot (FP) cavity. Detailed analysis of the curvature data was carried out using machine learning techniques, allowing accurate classification of curvature in both directions of rotation. The experimental results showed excellent agreement (R2: 0.9998) with the predicted values. The sensor exhibits a maximum error of 1.9485°. This approach presents significant potential for applications requiring accurate real-time curvature measurements.
Open Access
AI algorithms in the agrifood industry: application potential in the Spanish agrifood context
(MDPI, 2025-02-17) Arévalo Royo, Javier; Flor Montalvo, Francisco Javier; Latorre Biel, Juan Ignacio; Tino Ramos, Rubén; Martínez Cámara, Eduardo; Blanco Fernández, Julio; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
This research explores the prospective implementations of artificial intelligence (AI) algorithms within the agrifood sector, focusing on the Spanish context. AI methodologies, encompassing machine learning, deep learning, and neural networks, are increasingly integrated into various agrifood sectors, including precision farming, crop yield forecasting, disease diagnosis, and resource management. Utilizing a comprehensive bibliometric analysis of scientific literature from 2020 to 2024, this research outlines the increasing incorporation of AI in Spain and identifies the prevailing trends and obstacles associated with it in the agrifood industry. The findings underscore the extensive application of AI in remote sensing, water management, and environmental sustainability. These areas are particularly pertinent to Spain¿s diverse agricultural landscapes. Additionally, the study conducts a comparative analysis between Spain and global research outputs, highlighting its distinctive contributions and the unique challenges encountered within its agricultural sector. Despite the considerable opportunities presented by these technologies, the research identifies key limitations, including the need for enhanced digital infrastructure, improved data integration, and increased accessibility for smaller agricultural enterprises. The paper also outlines future research pathways aimed at facilitating the integration of AI in Spain's agriculture. It addresses cost-effective solutions, data-sharing frameworks, and the ethical and societal implications inherent to AI deployment.
Open Access
Electric plasma guided with ultrasonic fields
(American Association for the Advancement of Science, 2025-02-05) Irisarri Erviti, Josu; Ezcurdia Aguirre, Íñigo Fermín; Iriarte Cárdenas, Naroa; Sirkka, Marika; Nikolaev, Dmitry; Mäkinen, Joni; Martinez-Marchese, Alexander; Iablonskyi, Denys; Salmi, Ari; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
Electric plasma forms sparks in midair that transfer electrical current. This current can power high-voltage electronics, kill bacteria, produce tactile sensations, or be used for welding. However, the formation of the spark is chaotic and hard to control. Laser pulses can guide discharges but require high power and are disruptive and cumbersome to control. Here, we show that ultrasonic fields can guide plasma sparks, even around obstacles. The ultrasonic beams can be directed dynamically and within milliseconds, enabling precise, nondangerous, and fast control of high-voltage sparks. This phenomenon can be used for applications in high-voltage switching and plasma treatments.
Open Access
Towards a heat-resistant tethered micro-aerial vehicle for structure fire sensing
(MDPI, 2025-02-23) Aláez Gómez, Daniel; Prieto Míguez, Manuel; Villadangos Alonso, Jesús; Astrain Escola, José Javier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua
The collapse of structures during firefighter intervention is one of the greatest risks that firefighters must face when entering buildings. To reduce these risks, situational awareness is key. Although many advances have already been developed in wildland and outdoor fires, there is still room for improvement in structure fires. The development of a heat-resistant micro-aerial vehicle for indoor fires poses a series of challenges such as component cooling, battery management, and protection from impacts. In this paper, a heat-resistant tethered micro-aerial vehicle is designed, modeled through thermal analysis, and successfully tested in real-world conditions. This platform has been equipped with a micro-sized thermal sensing camera and first-person-view (FPV) camera, optimized for thermal management, to allow for situational awareness in structure fires.
Open Access
Evaluation of the potential of natural mining by-products as constituents of stabilized rammed earth building materials
(MDPI, 2025-05-06) Martín Antunes, Miguel Ángel; Perlot, Céline; Villanueva Roldán, Pedro; Abdallah, Rafik; Seco Meneses, Andrés; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this investigation, different natural by-products were used to modify the Particle Size Distribution (PSD) of a soil to evaluate their potential in Stabilized Rammed Earth (SRE) building. Three different mixes were manufactured: (i) a mix composed entirely of a clayey soil, (ii) a mix consisting of mining by-products and clayey soil and (iii) a mix entirely based on mining by-products. Unstabilized and stabilized samples of the mixes were manufactured using two cement dosages (2.5% and 5%), and the samples were tested for Unconfined Compressive Strength (UCS), soaked UCS, and wetting and drying tests. Mining by-products demonstrated significant potential in SRE building, as their addition to the clayey soil resulted in higher UCS values compared to the UCS obtained from clayey soil alone. Unstabilized samples lost their integrity during exposure to water. The inclusion of mining by-products also showed potential as, although the mixes did not fully meet the requirements for soaked UCS and the wetting and drying tests, the mix containing both mining by-products and clayey soil retained its integrity in water, unlike the samples composed solely of clayey soil. M3C5 successfully met the requirements for soaked UCS and the wetting and drying tests, further highlighting the great potential of mining by-products in SRE building.
Open Access
400 W facility of geothermal thermoelectric generators from hot dry rocks on the Canary Islands
(Elsevier, 2025-06-01) Alegría Cía, Patricia; Pascual Lezaun, Nerea; Catalán Ros, Leyre; Araiz Vega, Miguel; Astrain Ulibarrena, David; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Geothermal energy has a great potential to be harnessed and requires a boost in technologies to enhance its use. The Canary Islands have a great dependence on fossil fuels, and Lanzarote has important geothermal anomalies currently unexploited due to the absence of water in the soil, what hinders the use of vapour turbines. This work presents the development of the first facility of geothermal thermoelectric generators operating in the world. This novel generators are producing 400 W of power in Timanfaya National Park. It has three geothermal thermoelectric generators, each with 4 thermosyphons per borehole and 40 thermoelectric modules that directly transform heat into electricity. This facility, with the advantages of geothermal energy such as continuity and independence on the weather, requires low maintenance because it does not require moving parts nor water consumption. That makes feasible for the first time to harness the geothermal potential in Lanzarote, producing an electric energy of 9.4 kWh per day, which means 3.42 MWh per year. The field installation of this novel technology has enabled to accurately calculate the Levelized Cost of Energy, which is 0.22 €/kWh. Although a 29% decrease in the power generated by thermoelectric module was detected when installing a GTEG with 40 modules with respect to a GTEG with 10 modules, this decrease is compensated by the fact that by installing more modules, the electrical production per borehole is optimized, reducing the LCOE. The developed facility will avoid the emission of 2.3 tons of CO2 and is totally respectful with the environment if compared to conventional geothermal power plants.