Artículos de revista (CEIT)
Permanent URI for this collectionhttps://hdl.handle.net/10171/70227
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186 results
Results
- A CFD-based compartmental modelling approach for long-term dynamic simulation of water resource recovery facilities.(2024-07) Sanchez-Larraona, G. (Gorka); Elduayen-Echave, B. (Beñat); Hernández, B. (Borja); Romay-Gainza, A. (Asier); Arnau, R. (Rosario)This article presents a methodology for compartmental model (CM) creation for long-term simulation of water resource recovery facilities (WRRFs). CMs are often focused on reproducing with a lower computational cost than previously simulated scenarios. In contrast, the methodology presented here can represent variable hydraulic conditions, based on the interpolation of data gathered from a set of computational fluid dynamics simulations that reproduce representative hydraulic scenarios. This is achieved by modelling with bidirectional flows the exchange flows between fixed compartments, which are defined based on the geometry of the reactors. The resultant hydraulic surrogate model can be implemented in commercial water treatment software to solve biochemical kinetics. The methodology was applied to simulate in WEST (R)-DHI, a WRRF in Vila-Real, Spain. In this contribution, the CM was validated with real plant data. The developed CM provided a quick response simulation with a high level of hydraulic and biochemical detail. This allowed us to observe a spatial distribution of component concentration, which could help with sensor location or plant optimisation. The methodology presented here could also be a useful enabler of digital twins to be implemented in WRRF.
- Development of anisotropic Nd-Fe-B powder from isotropic gas atomized powder.(2024) Sarriegui-Estupiñan, G.C. (Gabriela Carolina); Ipatov, M.S. (Mihail S.); González, J. (Julián); Sheridan, R. (Richard); Pickering, L. (Lydia); Martín, J.M. (José Manuel); Degri, M. (Malik); Walton, A. (Allan); Burgos-García, N. (Nerea)This work presents an innovative approach to obtain anisotropic Nd-Fe-B powder from isotropic gas atomized powder. The new process was developed using a ternary Nd-Fe-B alloy, without the requirement for additional heavy rare earth or other critical raw materials. It comprises the following steps: (a) gas atomization to produce a polycrystalline isotropic powder; (b) annealing at high temperature to induce grain growth; (c) hydrogen decrepitation to obtain a monocrystalline powder; and (d) hydrogenation-disproportionation-desorptionrecombination to obtain the final ultrafine anisotropic particles. The final particle shape is polygonal, which should improve the injection molding characteristics of current powder. The final powder exhibits both high remanence (0.97 T) and coercivity (1354 kA/m) for laboratory batch sizes, which is a result of its anisotropic ultrafine microstructure. Thus, gas atomization is considered a feasible alternative to casting methods as a first step to produce powders for anisotropic bonded magnet.
- Fabrication of thin-wall structures with a femtosecond laser and stainless steel powder(MDPI, 2024) Castaño-Carmona, E. (Enrique); Rodríguez-González, A. (Ainara); Ramón-Conde, I. (Iñigo); Gómez-Aranzadi, M. (Mikel); Olaizola-Izquierdo, S.M. (Santiago Miguel); Omeñaca-Segura, L. (Luís)Additive Manufacturing (AM) has revolutionized the production of complex three-dimensional (3D) structures; however, the efficient and precise fabrication of thin profiles remains a challenge. This study explores the application of femtosecond-laser-based additive manufacturing techniques for the production of thin profiles with micron-scale features, reaching profile thicknesses below 100 mu m. The study investigates the effects of scanning strategy, with optimized processing parameters, on the fabrication of thin profiles; wall thickness measurements were carried out using various technologies to analyse the influence of each on the resulting values. The quality of the walls was quantified by means of a visual characterization of the melted volumes, analysing the evolution of the measured thickness with regard to the processing conditions and in relation to the theoretical thicknesses of the walls.
- Improving the reliability of a future more electric aircraft DC power system through a novel topology and software combination.(Elsevier, 2024) Echeverria-Ormaechea, J.M. (José Martín); Rodriguez-Lalane, F. (Fermin); Martínez-Zubizarreta, G. (Gaizka); Urnieta, M. (Mikel); Sánchez-Guardamino, I. (Ignacio)The More Electric Aircraft concept has arisen in an attempt to achieve the goals stated by different international organisations in terms of the concept of future aircraft. While some of these requirements are related to reducing the negative effects of airfreight such as CO2 emissions or fuel consumption, other requirements focus on aircraft safety enhancement. Nevertheless, if the way to achieve the vast majority of these goals is based on increasing electrification level of aircrafts, then their electric power system must be reviewed and reconsidered. Currently, literature proposes device redundancy as the main option for meeting aircraft safety requirements. This paper proposes alternative architecture, which consists of merging a new source code and recently developed topology, which makes it possible to decentralise the aircraft's DC bus, in order to increase its safety and meet the stated goals. While the new topology has been validated through small-scale prototyping, proposed software strategy has been validated in a virtual environment using simulations. The architecture developed enables a path to be selected in the electric power system: examining different options in the system, analysing which of those options are the most efficient and, finally, sending signals to configure the power system connections to power the load. Based on the results of those tests, the alternative proposed satisfactorily powers selected loads.
- Influence of salt and temperature in the growth of pathogenic free-living amoebae.(Frontiers media SA, 2024) Lorenzo-Morales, J. (Jacob); Sancho-Seuma, L. (Luis); Pinero, J.E. (José E.); Chao-Pellicer, J. (Javier); Sifaoui, I. (Inés); Urruticoechea, A. (Andoni); Rodríguez-Expósito, R. (Rubén); Arberas-Jiménez, I. (Iñigo)Introduction Free-living amoebae are an extensive group of protistans that can be found in a wide variety of environments. Among them, the Acanthamoeba genus and Naegleria fowleri stand out as two of the most pathogenic amoebae and with a higher number of reported cases. N. fowleri is mainly found in warm freshwater water bodies whereas amoebae of the Acanthamoeba genus are broadly distributed through natural and anthropogenic environments. In this regard, the management and the control of the amoebic populations in swimming pools has become a major public health challenge for institutions.Methods The aim of this work was to evaluate the growth pattern of trophozoites of A. griffini and N. fowleri at different temperatures and salt concentrations.Results and discussion Our results showed that A. griffini resisted a higher concentration of salt than N. fowleri. Moreover, no trophozoites could withstand the salt levels of the sea in in vitro conditions. This work supports the contention that salinity could represent an important and useful tool for the control of the most pathogenic amoebic populations in recreational water bodies.
- Single-step fabrication of highly tunable blazed gratings using triangular-shaped femtosecond laser pulses(2024) Fantova-Sarasa, J. (Jorge); Olaizola, S.M. (Santiago Miguel); Rodríguez-González, A. (Ainara); Gómez-Aranzadi, M. (Mikel); Lens, J. (José); Beldarrain, O. (Oihane); Omeñaca-Segura, L. (Luís); Garcia-Mandayo, G. (Gemma)Blazed gratings are periodic surface structures of great interest for applications such as friction control, light trapping, and spectrometry. While different laser processing methods have been explored to produce these elements, they have not yet surpassed conventional surface manufacturing techniques, often based on lithography processes or mechanical ruling. This work introduces a new approach based on the combination of ultrashort pulses and triangular beam shaping, which enables the generation of asymmetrical grooves in a single step. The main advantage of this strategy is that by simply changing the laser processing direction we can induce a significant modification in the ratio of asymmetry between the sidewall angles of the machined channels. The paper includes a comprehensive study, which has been supported by statistical tools, of the effect of this and other experimental parameters on the morphology of grooves machined on stainless steel. As a result, we achieved a wide range of geometries, with asymmetry ratios spanning from 1 to 5 and channel depths between 3 and 15 mu m. Furthermore, we demonstrate the validity of the approach through the successful manufacture of blazed gratings of various slopes. The results reflect the versatility and cost-efficiency of the proposed fabrication strategy, and thus its potential to streamline the production of sawtooth gratings and other devices that are based on asymmetrical features.
- Wave basin tests of a multi-body floating PV system sheltered by a floating breakwater.(MDPI, 2024) Delhaye, V.(Virgile); Pehlke, T.(Thomas); Van-der-Zanden, J.(Joep); Cortés, A. (Ainhoa); Bunnik, T.(Tim); Panjwani, B.(Balram); Kegelart, G.(Guillaume)The development of floating photovoltaic systems (FPV) for coastal and offshore locations requires a solid understanding of a design's hydrodynamic performance through reliable methods. This study aims to extend insights into the hydrodynamic behavior of a superficial multi-body FPV system in mild and harsh wave conditions through basin tests at scale 1:10, with specific interest in the performance of hinges that interconnect the PV panels. Particular effort is put into correctly scaling the elasticity of the flexible hinges that interconnect the PV modules. Tests of a 5 x 3 FPV matrix are performed, with and without shelter, by external floating breakwater (FBW). The results show that the PV modules move horizontally in the same phase when the wave length exceeds the length of the FPV system, but shorter waves result in relative motions between modules and, for harsh seas, in hinge buckling. Relative motions suggest that axial loads are highest for the hinges that connect the center modules in the system and for normal wave incidence, while shear loads are highest on the outward hinges and for oblique incidence. The FBW reduces hinge loads as it attenuates the high-frequency wave energy that largely drives relative motions between PV modules.
- Wear study of additively manufactured repair material for R260 grade rails.(2024) San-Emeterio, A. (Albi); Veiga, A. (Angela); Salas-Vicente, F.; López-López, J.; Schiopetto, F.; Rodríguez-de-Arana, B. (Borja); Ausejo-Muñoz, S. (Sergio); Pérez-Casero, I. (Iñigo)Additive Manufacturing (AM) has been considered as a promising method for repairing rails and extending their service life. In this work, the wear rates of twin-disc specimens produced through laser additive manufacturing against ER7 material are studied applying creepages from 0.4 % to 2.6 %. The approved E11018-G electrode material is atomised and fully cladded into twin-disc rail specimens by Laser Powder Directed Energy Deposition. After the weight loss tests at 1400 MPa, experimental results are fitted with the theoretical adhesion curve modifying FASTSIM coefficients. This adhesion curve is employed to numerically calculate the slip contact area of each test. A non-linear correlation has been found and defined between wear and the slip area including the non-linear zone. This relationship is identified for tribochemical wear for low creepages and delaminative wear for middle and high creepages by surface and metallographic characterisation. The obtained results allow to predict the wear of the additively manufactured E11018-G repair material under wheel-rail contact conditions when the slip area is known.
- Wearable voice dosimetry system.(MDPI, 2024) Fernández-González, S. (Secundino); Llorente-Ortega, M. (Marcos); Podhorski, A. (Adam)The objective quantification of voice acoustic parameters is used for the diagnosis, monitoring, and treatment of voice disorders. Such assessments are carried out with specialised equipment within the doctor's office. The controlled conditions employed are usually not those of the real environment of the patient. The results, although very informative, are specific to those measurement conditions and to the time when they were performed. A wearable voice monitoring system, based on an accelerometer to ensure the message, can overcome these limitations. We present a miniaturised, low-power, and low-cost wearable system to estimate and record voice fundamental frequency (F0), intensity and phonation time for long intervals in the everyday environment of the patient. It was tested on two subjects for up to two weeks of recording time. It was possible to identify distinct periods in vocal activity, such as normal, professional, demanding or hyperfunctional. It provided information on the workload that the vocal cords needed to cope with over time and when and to what extent that workload was concentrated. The proposed voice dosimetry system enables the extraction and recording of voice parameters for long periods of time in the everyday environment of the patient, allowing the objectification of vocal risk situations and personalised treatment and monitoring.
- Control method based on real–imaginary decomposition at the switching frequency for multiple active bridge converters.(Willey, 2024) Martín-Porres, F. (Fernando); Shubnaya, A. (Anna); Ibañez, F.M.(Federico M.)Isolated multiple port DC/DC converters, such as the Multiple Active Bridge (MAB) converter, have many recent applications, such as interconnection between grids, isolated uninterruptible power sources (UPSs) and electric vehicle chargers. MAB converter is an attractive solution from the point of view of the hardware because of its symmetry and its capability to be extended to any number of bridges with a moderate number of components. However, the main challenge of this converter is the control method in order to achieve independent control between the different ports and to minimize recirculating currents. For that reason, three-port power converters have been already investigated, but many improvements can be done for a larger number of ports. This paper proposes to use a Fourier decomposition for the main power signals to separate their real and imaginary parts. As the signals work at the switching frequency, this decomposition is developed with analog electronics. Based on that, a general control method for regulating the power at the different ports is presented using the first harmonic component, which delivers most of the power. In this proposal, two nested control loops ensure accuracy for the DC power flow. Simulation and experimental results validate the proposal. The paper proposes an independent method of control of a multi active bridge converter based on a dq-decomposition at the switching frequency. The method allows a fast response and an independent control of bidirectional power flow in all of the ports.image