• 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 and robust ellipse detection algorithm for head-mounted eye tracking systems 

      Martinikorena Aranburu, Ion Upna Orcid; Cabeza Laguna, Rafael Upna Orcid; Villanueva Larre, Arantxa Upna Orcid; Urtasun, Iñaki; Larumbe Bergera, Andoni Upna Orcid (Springer, 2018)   Artículo / Artikulua  OpenAccess
      In head-mounted eye tracking systems, the correct detection of pupil position is a key factor in estimating gaze direction. However, this is a challenging issue when the videos are recorded in real-world conditions, due ...
    • 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 ...
    • 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
    • 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 ...
    • Freehand system for antenna diagnosis based on amplitude-only data 

      Álvarez Narciandi, Guillermo; Laviada, Jaime; Álvarez López, Yuri; Ducournau, Guillaume; Luxe, Cyril; Belem Goncalves, Cybelle; Gianesello, Frederic; Nachabe, Nour; Río Bocio, Carlos del Upna Orcid; Las-Heras, Fernando (IEEE, 2021)   Artículo / Artikulua  OpenAccess
      This article presents a portable system for freehand antenna diagnosis and characterization based on amplitude-only data. The amplitude-only samples are acquired by moving a handheld probe, which is tracked by a motion ...
    • 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 ...
    • Fundamental radiative processes in near-zero-index media of various dimensionalities 

      Lobet, Michaël; Liberal Olleta, Íñigo Upna Orcid; Knall, Erik N.; Alam, M. Zahirul; Reshef, Orad (American Chemical Society, 2020)   Artículo / Artikulua  OpenAccess
      Spontaneous emission, stimulated emission and absorption are the three fundamental radiative processes describing light-matter interactions. Here, we theoretically study the behavior of these fundamental processes inside ...
    • Future smartphone: MIMO antenna system for 5G mobile terminals 

      Mujeeb, Abdullah; Altaf, Ahsan; Anjum, Muhammad Rizwan; Arain, Zulfiqar Ali; Jamali, Abdul Aleem; Alibakhshikenari, Mohammad; Falcone Lanas, Francisco Javier Upna Orcid; Limiti, Ernesto (IEEE, 2021)   Artículo / Artikulua  OpenAccess
      In this article, an inverted L-shaped monopole eight elements Multiple Input Multiple Output (MIMO) antenna system is presented. The multi-antenna system is designed on a low cost 0.8 mm thick FR4 substrate having dimensions ...
    • Fuzzy logic-based energy management system design for residential grid-connected microgrids 

      Arcos Avilés, Diego; Pascual Miqueleiz, Julio María Upna Orcid; Marroyo Palomo, Luis Upna Orcid; Sanchis Gúrpide, Pablo Upna Orcid; Guinjoan Gispert, Francesc (IEEE, 2018)   Artículo / Artikulua  OpenAccess
      This paper presents the design of a low complexity fuzzy logic controller of only 25-rules to be embedded in an energy management system for a residential grid-connected microgrid including renewable energy sources and ...
    • Gain-boosted super class AB OTAs based on nested local feedback 

      Beloso Legarra, Javier Upna Orcid; Cruz Blas, Carlos Aristóteles de la Upna Orcid; López Martín, Antonio Upna Orcid; Ramírez-Angulo, Jaime (IEEE, 2021)   Artículo / Artikulua  OpenAccess
      A new approach to design super class AB operational transcon-ductance amplifiers (OTAs) with enhanced large-signal and small-signal performance is presented. It is based on employing two nested positive and negative feedback ...
    • Gamification for photonics students: labescape 

      Pérez Herrera, Rosa Ana Upna Orcid; Tainta Ausejo, Santiago Upna Orcid; Elosúa Aguado, César Upna Orcid (MDPI, 2021)   Artículo / Artikulua  OpenAccess
      The idea of utilizing game elements in non-gaming situations has sparked a lot of attention in recent years, especially in topics such as education and training. Game-based techniques appear to be an increasing trend in a ...

      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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