• Fabrication of Bragg gratings on the end facet of standard optical fibers by sputtering the same material 

      Ascorbe Muruzabal, Joaquín Upna Orcid; Corres Sanz, Jesús María Upna Orcid; Del Villar, Ignacio Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid; Matías Maestro, Ignacio Upna Orcid (IEEE, 2016)   Artículo / Artikulua  OpenAccess
      A sputtering process has been applied to deposit quarter-wavelength stacks on the end facet of cleaved optical fibers by using only one sputtering target. Standard multimode optical fibers were used as substrates to fabricate ...
    • Fabrication of long period gratings by periodically removing the coating of cladding-etched single mode optical fiber towards optical fiber sensor development 

      Ascorbe Muruzabal, Joaquín Upna Orcid; Corres Sanz, Jesús María Upna Orcid; Del Villar, Ignacio Upna Orcid; Matías Maestro, Ignacio Upna Orcid (MDPI, 2018)   Artículo / Artikulua  OpenAccess
      Here, we present a novel method to fabricate long period gratings using standard single mode optical fibers (SMF). These optical devices were fabricated in a three-step process, which consisted of etching the SMF, then ...
    • A family of alternating current amplifiers for ultra-low frequency operation 

      Martincorena Arraiza, Maite Upna Orcid; Carlosena García, Alfonso Upna Orcid; Cruz Blas, Carlos Aristóteles de la Upna Orcid; Beloso Legarra, Javier Upna Orcid; López Martín, Antonio Upna Orcid (Wiley, 2021)   Artículo / Artikulua  OpenAccess
      A family of capacitively coupled alternating current (AC) amplifiers featuring ultra-low (below 1 Hz) corner frequency is presented. This is achieved by using high-gain devices which actively boost feedback resistance and ...
    • Far-field and near-field physics of extraordinary THz transmitting hole-array antennas 

      Camacho, Miguel; Boix, Rafael R.; Kuznetsov, Sergei A.; Beruete Díaz, Miguel Upna Orcid; Navarro Cía, Miguel Upna Orcid (IEEE, 2019)   Artículo / Artikulua  OpenAccess
      Despite three decades of effort, predicting accurately extraordinary transmission through subwavelength hole arrays has proven challenging. The lack of quantitative design and modeling capability to take into account ...
    • Fast capacity and internal resistance estimation method for second-life batteries from electric vehicles 

      Braco Sola, Elisa Upna; San Martín Biurrun, Idoia Upna Orcid; Sanchis Gúrpide, Pablo Upna Orcid; Ursúa Rubio, Alfredo Upna Orcid (Elsevier, 2023)   Artículo / Artikulua  OpenAccess
      The success of second-life (SL) Li-ion batteries from electric vehicles is still conditioned by their technical and economic viability. The knowledge of the internal parameters of retired batteries at the repurposing stage ...
    • Fault detection of planetary gears based on signal space constellations 

      Martincorena Arraiza, Maite Upna Orcid; Cruz Blas, Carlos Aristóteles de la Upna Orcid; López Martín, Antonio Upna Orcid; Molina Vicuña, Cristian; Matías Maestro, Ignacio Upna Orcid (MDPI, 2022)   Artículo / Artikulua  OpenAccess
      A new method to process the vibration signal acquired by an accelerometer placed in a planetary gearbox housing is proposed, which is useful to detect potential faults. The method is based on the phenomenological model and ...
    • FDTD and empirical exploration of human body and UWB radiation interaction on TOF ranging 

      Otim, Timothy Upna; Bahillo, Alfonso; Díez, Luis E.; López Iturri, Peio Upna Orcid; Falcone Lanas, Francisco Upna Orcid (IEEE, 2019)   Artículo / Artikulua  OpenAccess
      In time-of-flight (TOF)-based human ranging systems, target sensors are often mounted on or close to the human body, which may raise non-line-of-sight (NLOS) cases and lead to significant ranging errors depending on the ...
    • Feasibility of vermicomposting of spent coffee grounds and silverskin from coffee industries: a laboratory study 

      González Moreno, Miguel Ángel Upna Orcid; Marcelino Sádaba, Sara Upna Orcid; Zaratiegui Urdin, Javier Upna; Robles Domínguez, Estrella Upna; Pérez Ezcurdia, Amaya Upna Orcid; Seco Meneses, Andrés Upna Orcid (MDPI, 2020)   Artículo / Artikulua  OpenAccess
      In the coffee industry, several by-products are generated during the production and consumption of coffee and represent an important waste from an environmental viewpoint. For improving the knowledge about this issue, a ...
    • Femtomolar detection by nanocoated fiber label-free biosensors 

      Chiavaioli, Francesco; Zubiate Orzanco, Pablo Upna Orcid; Del Villar, Ignacio Upna Orcid; Ruiz Zamarreño, Carlos Upna Orcid; Giannetti, Ambra; Tombelli, Sara; Trono, Cosimo; Arregui San Martín, Francisco Javier Upna Orcid; Matías Maestro, Ignacio Upna Orcid; Baldini, Francesco (ACS, 2018)   Artículo / Artikulua  OpenAccess
      The advent of optical fibre-based biosensors combined with that of nanotechnologies has provided an oppor-tunity for developing in situ, portable, lightweight, versatile and high-performance optical sensing platforms. We ...
    • Fiber-based early diagnosis of venous thromboembolic disease by label-free D-dimer detection 

      Zubiate Orzanco, Pablo Upna Orcid; Urrutia Azcona, Aitor Upna Orcid; Ruiz Zamarreño, Carlos Upna Orcid; Egea Urra, Josune; Fernández Irigoyen, Joaquín Upna Orcid; Giannetti, Ambra; Baldini, Francesco; Díaz Lucas, Silvia Upna Orcid; Matías Maestro, Ignacio Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid; Santamaría, Enrique; Chiavaioli, Francesco; Del Villar, Ignacio Upna Orcid (Elsevier, 2019)   Artículo / Artikulua  OpenAccess
      D-dimer is a useful diagnostic biomarker for deep vein thrombosis or pulmonary embolism, collectively referred to as venous thromboembolism (VTE). The ability to detect in real-time the amount of D-dimer with a fast and ...
    • Fiber-optic biosensor based on lossy mode resonances 

      Socorro Leránoz, Abián Bentor Upna Orcid; Corres Sanz, Jesús María Upna Orcid; Del Villar, Ignacio Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid; Matías Maestro, Ignacio (Elsevier, 2012)   Artículo / Artikulua
    • Field test of a geothermal thermoelectric generator without moving parts on the Hot Dry Rock field of Timanfaya National Park 

      Catalán Ros, Leyre Upna Orcid; Alegría Cía, Patricia; Araiz Vega, Miguel Upna Orcid; Astrain Ulibarrena, David Upna Orcid (Elsevier, 2023)   Artículo / Artikulua  OpenAccess
      Although in the last years thermoelectric generators have arisen as a solution to boost geothermal power generation, tests on field are still scarce. The vast majority of the available studies focus on computational ...
    • Fifth-generation (5G) mmwave spatial channel characterization for urban environments’ system analysis 

      Azpilicueta Fernández de las Heras, Leyre Upna Orcid; López Iturri, Peio Upna Orcid; Zuñiga Mejia, Jaime; Aguirre Gallego, Erik Upna Orcid; Falcone Lanas, Francisco Javier Upna Orcid (MDPI, 2020)   Artículo / Artikulua  OpenAccess
      In this work, the channel characterization in terms of large-scale propagation, small-scale propagation, statistical and interference analysis of Fifth-Generation (5G) Millimeter Wave (mmWave) bands for wireless networks ...
    • Fluorescent sensors for the detection of heavy metal ions in aqueous media 

      Acha Morrás, Nerea de Upna Orcid; Elosúa Aguado, César Upna Orcid; Corres Sanz, Jesús María Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid (MDPI, 2019)   Artículo / Artikulua  OpenAccess
      Due to the risks that water contamination implies for human health and environmental protection, monitoring the quality of water is a major concern of the present era. Therefore, in recent years several efforts have been ...
    • A framework for generalized monotonicity of fusion functions 

      Sesma Sara, Mikel Upna Orcid; Šeliga, Adam; Boczek, Michał; Jin, LeSheng; Kaluszka, Marek; Kalina, Martin; Bustince Sola, Humberto Upna Orcid; Mesiar, Radko (Elsevier, 2023)   Artículo / Artikulua  OpenAccess
      The relaxation of the property of monotonicity is a trend in the theory of aggregation and fusion functions and several generalized forms of monotonicity have been introduced, most of which are based on the notion of ...
    • A framework for radial data comparison and its application to fingerprint analysis 

      Marco Detchart, Cedric Upna Orcid; Cerrón González, Juan Upna; Miguel Turullols, Laura de Upna Orcid; López Molina, Carlos Upna Orcid; Bustince Sola, Humberto Upna Orcid; Galar Idoate, Mikel Upna Orcid (Elsevier, 2016)   Artículo / Artikulua  OpenAccess
      This work tackles the comparison of radial data, and proposes comparison measures that are further applied to fingerprint analysis. First, we study the similarity of scalar and non-scalar radial data, elaborated on previous ...
    • A frequency reconfigurable compact planar inverted-F antenna for portable devices 

      Ghaffar, Adnan; Altaf, Ahsan; Aneja, Aayush; Li, Xue Jun; Khan, Salahuddin; Alibakhshikenari, Mohammad; Falcone Lanas, Francisco Javier Upna Orcid; Limiti, Ernesto (Hindawi, 2022)   Artículo / Artikulua  OpenAccess
      In this paper, a low-profile, compact size, inexpensive, and easily integrable frequency reconfigurable antenna system is proposed. The proposed antenna consists of an inverted-F shape antenna, capacitors, and switching ...
    • From 2G to 5G spatial modeling of personal RF-EMF exposure within urban public trams 

      Celaya Echarri, Mikel Upna Orcid; Azpilicueta Fernández de las Heras, Leyre Upna Orcid; Karpowicz, Jolanta; López Iturri, Peio Upna Orcid; Falcone Lanas, Francisco Javier Upna Orcid (IEEE, 2020)   Artículo / Artikulua  OpenAccess
      The upcoming design and implementation of the new generation of 5G cellular systems, jointly with the multiple wireless communication systems that nowadays coexist within vehicular environments, leads to Heterogeneous ...
    • From fundamental materials chemistry to sensing applications: unravelling the water adsorption mechanism of a luminescent optical fibre sensor membrane 

      Cruz Quesada, Guillermo Upna Orcid; Rosales Reina, Beatriz; López Torres, Diego Upna Orcid; Reinoso, Santiago Upna Orcid; López Ramón, María Victoria; Arzamendi Manterola, María Cruz Upna Orcid; Elosúa Aguado, César Upna Orcid; Espinal Viguri, Maialen Upna Orcid; Garrido Segovia, Julián José Upna Orcid (Elsevier, 2024)   Artículo / Artikulua  OpenAccess
      This work provides insight into the correlation between the luminescent response of a water-vapour optical fibre sensor and the textural properties of its lanthanide-doped silica coating. To this end, a library of 16 silica ...
    • From fuzzy sets to interval-valued and Atanassov intuitionistic fuzzy sets: a unified view of different axiomatic measures 

      Couso, Inés; Bustince Sola, Humberto Upna Orcid (IEEE, 2019)   Artículo / Artikulua  OpenAccess
      We examine a broad collection of axiomatic definitions from various and diverse contexts, within the domain of fuzzy sets. We evaluate their respective extensions to the case of interval-valued fuzzy sets and intuitionistic ...

      El Repositorio ha recibido la ayuda de la Fundación Española para la Ciencia y la Tecnología para la realización de actividades en el ámbito del fomento de la investigación científica de excelencia, en la Línea 2. Repositorios institucionales (convocatoria 2020-2021).
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