Person: Alfaro López, José Ramón
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Alfaro López
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José Ramón
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Ingeniería
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0000-0003-4746-1018
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Publication Open Access The use of virtual sensors for bead size measurements in wire-arc directed energy deposition(MDPI, 2024) Fernández Zabalza, Aitor; Veiga Suárez, Fernando; Suárez, Alfredo; Alfaro López, José Ramón; Ingeniería; IngeniaritzaHaving garnered significant attention in the scientific community over the past decade, wire-arc directed energy deposition (arc-DED) technology is at the heart of this investigation into additive manufacturing parameters. Singularly focused on Invar as the selected material, the primary objective revolves around devising a virtual sensor for the indirect size measurement of the bead. This innovative methodology involves the seamless integration of internal signals and sensors, enabling the derivation of crucial measurements sans the requirement for direct physical interaction or conventional measurement methodologies. The internal signals recorded, the comprising voltage, the current, the energy from the welding heat source generator, the wire feed speed from the feeding system, the traverse speed from the machine axes, and the temperature from a pyrometer located in the head were all captured through the control of the machine specially dedicated to the arc-DED process during a phase of optimizing and modeling the bead geometry. Finally, a feedforward neural network (FNN), also known as a multi-layer perceptron (MLP), is designed, with the internal signals serving as the input and the height and width of the bead constituting the output. Remarkably cost-effective, this solution circumvents the need for intricate measurements and significantly contributes to the proper layer-by-layer growth process. Furthermore, a neural network model is implemented with a test loss of 0.144 and a test accuracy of 1.0 in order to predict weld bead geometry based on process parameters, thus offering a promising approach for real-time monitoring and defect detection.Publication Open Access The integration of mechanical energy absorbers into rollover protective structures to improve the safety of agricultural tractors in the event of rollover(MDPI, 2024) Alfaro López, José Ramón; Pérez Ezcurdia, Amaya; Latorre Biel, Juan Ignacio; Arana Navarro, Ignacio; Benito Amurrio, Marta; Villanueva Roldán, Pedro; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA1912The combination of safety belts and rollover protective structures (ROPSs) is key in improving the safety of agricultural tractors in the event of rollover. However, we also have the opportunity to enhance the security provided by each ROPS; one such example is the combination of this safety device with adequate mechanical energy absorbers (MEAs). Inexpensive disc-shaped MEAs can be included in the anchoring points of a ROPS onto the chassis of a tractor. Three configurations of ROPS combined with MEAs were tested during the application of loads that simulated the effects of side rollover in the vehicle. The tested configurations included a blank MEA as a reference case alongside a single MEA and a stack assembly containing both elements. The results of the tests show that both the deformation of the ROPS itself and the strain energy are larger in the case of blank MEAs; thus, there is also a risk that the clearance zone will be infringed upon and that the protective structure will collapse. We can conclude that the implementation of an appropriate MEA in ROPS reduces the deformation of the ROPS itself and its strain energy in cases of vehicle rollover; hence, the safety provided by such protection systems may be improved at a low cost.Publication Open Access Influence of geometry in the behavior of disc-shaped mechanical energy absorbers for agricultural tractors(MDPI, 2021) Latorre Biel, Juan Ignacio; Pérez Ezcurdia, Amaya; Benito Amurrio, Marta; Alfaro López, José Ramón; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaDisc-shaped mechanical energy absorbers (MEAs), in combination with rollover protection structures (ROPSs), may contribute to the prevention of the infringement of the safety zone and the collapse of the ROPS in case of the overturn of an agricultural tractor. An MEA can absorb a significant amount of potential energy of an overturning tractor and its deformation produces a rotation of the ROPS around the safety zone. In this research, MEAs with two different geometries have been developed. Both geometries present common features, such as disc dimensions, number of rings, and number of arms, but the distribution of the arms differs. Additionally, these MEA were manufactured in steel discs of four different thicknesses, ranging from 2 to 6 mm. The manufactured MEAs were tested in a universal testing machine, and their behavior characterized. From this data, linear models of the MEAs were developed. As a consequence, a number of characteristic parameters were selected and calculated, such as the activation load and the strain energy absorbed in a safe range of applied loads. Some patterns and trends were analyzed from the tested MEAs, which enables a better description of their behavior and the extrapolation of this behavior to other non-tested thicknesses and geometries.Publication Open Access Development and tests of a neonatal portable foldable emergency incubator(World Scientific, 2018) Ballesteros Egüés, Tomás; Arana Navarro, Ignacio; Pérez Ezcurdia, Amaya; Alfaro López, José Ramón; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISCPublication Open Access Development of an inexpensive rollover energy dissipation device to improve safety provided by ROPS(Elsevier, 2019) Latorre Biel, Juan Ignacio; Ballesteros Egüés, Tomás; Arana Navarro, Ignacio; Alfaro López, José Ramón; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISCPublication Open Access Evaluation of risk factors in fatal accidents in agriculture(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 2010) Arana Navarro, Ignacio; Mangado Ederra, Jesús; Arnal Atarés, Pedro; Arazuri Garín, Silvia; Alfaro López, José Ramón; Jarén Ceballos, Carmen; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta ProiektuakEn el ámbito agrario se producen anualmente muchos accidentes mortales, no siendo todos ellos registrados oficialmente como accidentes laborales. El objetivo de esta investigación es comparar los datos reales y oficiales de accidentes agrícolas mortales y caracterizar los principales riesgos asociados a ellos. Un estudio sobre 388 accidentes mortales ocurridos en España con maquinaria agrícola en los últimos cinco años ha mostrado que sólo el 61,85% de ellos ha tenido carácter oficial. Las personas mayores fueron el sector de la población con un mayor riesgo, seguidos de los niños y las personas ajenas al sector agrario. La mayoría de las muertes registradas fueron debidas al vuelco de tractores sin estructuras de protección. De las 272 muertes causadas por accidentes con vuelco del tractor, sólo una sucedió en un tractor con estructura de protección homologada. La mayoría de los vuelcos se produjo en trayectos por carreteras o caminos, aunque las fuertes pendientes y los baches también son un factor de riesgo. Se han caracterizado once factores de riesgo y se ha comprobado que para que ocurra un accidente generalmente es necesario que confluyan, al menos, dos factores de riesgo y que la mayoría de los accidentes son causados por la concurrencia de tres o más de estos factores. Todos los accidentes son evitables porque requieren la coincidencia de más de un factor de riesgo. Si intentamos evitar todos los factores de riesgo, es posible que exista uno de estos factores, pero es muy difícil que concurran dos o más de ellos a la vez.