Now showing items 231-250 of 292

    • Second-order non-local effects mitigation in BOTDA sensors by tracking the BFS profile 

      Mompó Roselló, Juan José Upna; Iribas Pardo, Haritz Upna; Urricelqui Polvorinos, Javier Upna; Loayssa Lara, Alayn Upna (SPIE, 2017)   Contribución a congreso / Biltzarrerako ekarpena  OpenAccess
      We demonstrate a technique to mitigate the residual second-order non-local effects in Brillouin optical time-domain analysis (BOTDA) sensors in which the Brillouin frequency shift (BFS) profile is not uniform along the ...
    • Second-order nonlocal effects mitigation in Brillouin optical time-domain analysis sensors by tracking the Brillouin frequency shift profile of the fiber 

      Mompó Roselló, Juan José Upna; Iribas Pardo, Haritz Upna; Urricelqui Polvorinos, Javier Upna; Loayssa Lara, Alayn Upna (IEEE, 2017)   Artículo / Artikulua  OpenAccess
      We report on an additional limitation that has been found in Brillouin optical time-domain analysis (BOTDA) sensors due to the so-called second-order nonlocal effects (NLE). Second-order NLE appear in BOTDA setups that ...
    • Sensitivity enhancement experimental demonstration using a low cutoff wavelength SMS modified structure coated with a pH sensitive film 

      Rodríguez-Rodríguez, W.E.; Del Villar, Ignacio Upna; Ruiz Zamarreño, Carlos Upna; Matías Maestro, Ignacio Upna; Arregui San Martín, Francisco Javier Upna; Rodríguez Rodríguez, Adolfo Josué; Domínguez-Cruz, R.F. (Elsevier, 2018)   Artículo / Artikulua
      The multimode interference (MMI) effect in a single mode-multimode-single mode (SMS) can be used fordevelopment of wavelength shift detection based sensors. In this work, the focus is centered on obtainingwavelength shifts ...
    • Sensitivity enhancement in low cutoff wavelength long-period fiber gratings by cladding diameter reduction 

      Del Villar, Ignacio Upna; Partridge, Matthew; Rodríguez, Wenceslao; Fuentes, Omar; Socorro Leránoz, Abián Bentor Upna; Díaz Lucas, Silvia Upna; Corres Sanz, Jesús María Upna; James, Stephen; Tatam, Ralph (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      The diameter of long-period fiber gratings (LPFGs) fabricated in optical fibers with a low cutoff wavelength was be reduced by hydrofluoric acid etching, enhancing the sensitivity to refractive index by more than a factor ...
    • Sensitivity improvement of a humidity sensor based on silica nanospheres on a long-period fiber grating 

      Viegas, Diana; Goicoechea Fernández, Javier Upna; Santos, José Luís; Araújo, Francisco Moita; Ferreira, Luis Alberto; Arregui San Martín, Francisco Javier Upna; Matías Maestro, Ignacio Upna (MDPI, 2009)   Artículo / Artikulua  OpenAccess
      This work addresses a new configuration that improves the sensitivity of a humidity sensor based on a long-period fiber grating coated with a SiO(2)-nanospheres film. An intermediate higher refractive index overlay, ...
    • Sensitivity optimization with cladding-etched long period fiber gratings at the dispersion turning point 

      Del Villar, Ignacio Upna; Cruz, José Luis; Socorro Leránoz, Abián Bentor Upna; Corres Sanz, Jesús María Upna; Matías Maestro, Ignacio Upna (Optical Society of America, 2016)   Artículo / Artikulua  OpenAccess
      This work presents a refractive index sensor based on a long period fiber grating (LPFG) made in a reduced cladding fiber whose low order cladding modes have the turning point at large wavelengths. The combination of ...
    • Sensors based on thin-film coated cladding removed multimode optical fiber and single-mode multimode single-mode fiber: a comparative study 

      Del Villar, Ignacio Upna; Socorro Leránoz, Abián Bentor Upna; Hernáez Sáenz de Zaitigui, Miguel Upna; Corres Sanz, Jesús María Upna; Ruiz Zamarreño, Carlos Upna; Sánchez Zábal, Pedro Upna; Arregui San Martín, Francisco Javier Upna; Matías Maestro, Ignacio Upna (Hindawi Publishing Corporation, 2015)   Artículo / Artikulua  OpenAccess
      Two simple optical fibre structures that do not require the inscription of a grating, a cladding removed multimode optical fibre (CRMOF) and a single-mode multimode single-mode structure (SMS), are compared in terms of ...
    • Signal processing in ocean bottom seismographs for refraction seismology 

      Rodríguez Barbarin, Iban; Mànuel Lázaro, Antonio; Carlosena García, Alfonso Upna; Bermúdez, Antoni; Río, Joaquín del; Panahi, Shahram Shariat (IEEE, 2006)   Artículo / Artikulua  OpenAccess
      This paper presents some experimental results on the application of signal processing techniques to underwater seismic signals. The novelty of this paper stems from the fact that it is the first paper, to the best of the ...
    • Simple modelling of DGS to design 1D-PBG low-pass filters 

      Garde Irigoyen, Ieltxu Aitor Upna; Yábar, Miguel Javier; Río Bocio, Carlos del Upna (Wiley, 2003)   Artículo / Artikulua  OpenAccess
      The use of defected ground structures (DGS) is being intensively explored by the microwave filter designer community. The DGSs are one possible implementation of a 1D Photonic Band Gap (1D-PBG) where some defect structures ...
    • Simplifying the feeding network for multi-beam circular antenna arrays by using corps 

      Panduro, Marco A.; Río Bocio, Carlos del Upna (EMW Publishing, 2011)   Artículo / Artikulua  OpenAccess
      An innovative way to analyze the design of beam-forming networks (BFN) for scannable multi-beam circular antenna arrays using the CORPS (Coherently Radiating Periodic Structures) concept is introduced. This design of ...
    • Simultaneous measurement of humidity and vibration based on a nanowire sensor system using Fast Fourier Transform technique 

      Rota Rodrigo, Sergio Upna; López Aldaba, Aitor Upna; Pérez Herrera, Rosa Ana Upna; López Bautista, María del Carmen; Esteban, Óscar; López-Amo Sáinz, Manuel Upna (IEEEOptical Society of America, 2016)   Artículo / Artikulua  OpenAccess
      This paper presents a new sensor system for vibration and relative humidity measurements based on its interaction with the evanescent field of a microwire. The interrogation of the sensing head is carried out by monitoring ...
    • Single-longitudinal mode laser structure based on a very narrow filtering technique 

      Rodríguez Cobo, L.; Quintela, M. A.; Rota Rodrigo, Sergio Upna; López-Amo Sáinz, Manuel Upna; López Higuera, José Miguel (Optical Society of America, 2013)   Artículo / Artikulua  OpenAccess
      A narrow filtering technique based on the spectral overlapping of two uniform FBGs and applied to obtain a Single Longitudinal Mode (SLM) laser is proposed and demonstrated in this work. The two FBGs are spectrally detuned ...
    • Single-longitudinal-mode dual wavelength-switchable fiber laser based on superposed fiber bragg gratings 

      Pérez Herrera, Rosa Ana Upna; Rodriguez-Cobo, L.; Quintela, M. A.; López Higuera, José Miguel; López-Amo Sáinz, Manuel Upna (IEEE, 2015)   Artículo / Artikulua  OpenAccess
      n this work, a simple switchable dual-wavelength short-cavity fiber laser operating in a single-longitudinal-mode regime at room temperature and based on superposed fiber Bragg gratings is proposed and experimentally ...
    • A slow light fishnet-like absorber in the millimeter-wave range 

      Navarro Cía, Miguel Upna; Torres Landívar, Víctor Upna; Beruete Díaz, Miguel Upna; Sorolla Ayza, Mario Upna (EMW Publishing, 2011)   Artículo / Artikulua  OpenAccess
      A novel route to achieve a narrowband free-space electromagnetic absorber in any range of the spectrum based on stacked subwavelength hole arrays is proposed. The absorption is obtained by means of a slow light mode inside ...
    • Small wind turbines sensorless MPPT: robustness analysis and lossless approach 

      Urtasun Erburu, Andoni Upna; Sanchis Gúrpide, Pablo Upna; Marroyo Palomo, Luis Upna (IEEE, 2014)   Artículo / Artikulua  OpenAccess
      The configuration Permanent Magnet Synchronous Generator (PMSG) with diode bridge is frequently used in small Wind Energy Conversion Systems (WESC) thanks to its reliability and low cost. In order to perform a sensorless ...
    • Soret fishnet metalens antenna 

      Orazbayev, Bakhtiyar Upna; Beruete Díaz, Miguel Upna; Pacheco Peña, Víctor Upna; Crespo López, Gonzalo; Teniente Vallinas, Jorge Upna; Navarro Cía, Miguel Upna (Springer Nature, 2015)   Artículo / Artikulua  OpenAccess
      At the expense of frequency narrowing, binary amplitude-only diffractive optical elements emulate refractive lenses without the need of large profiles. Unfortunately, they also present larger Fresnel reflection loss ...
    • Spatial characterization of radio propagation channel in urban vehicle-to-infrastructure environments to support WSNs deployment 

      Granda, Fausto; Azpilicueta Fernández de las Heras, Leyre Upna; Vargas Rosales, César; López Iturri, Peio Upna; Aguirre Gallego, Erik Upna; Astrain Escola, José Javier Upna; Villadangos Alonso, Jesús Upna; Falcone Lanas, Francisco Javier Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      Vehicular ad hoc Networks (VANETs) enable vehicles to communicate with each other as well as with roadside units (RSUs). Although there is a significant research effort in radio channel modeling focused on vehicle-to-vehicle ...
    • Spectral evolution with incremental nanocoating of long period fiber gratings 

      Del Villar, Ignacio Upna; Corres Sanz, Jesús María Upna; Achaerandio, Miguel Upna; Arregui San Martín, Francisco Javier Upna; Matías Maestro, Ignacio Upna (Optical Society of America, 2006)   Artículo / Artikulua  OpenAccess
      The incremental deposition of a thin overlay on the cladding of a long-period fiber grating (LPFG) induces important resonance wavelength shifts in the transmission spectrum. The phenomenon is proved theoretically with ...
    • Split ring resonator-based left-handed coplanar waveguide 

      Martín, F.; Bonache, J.; Falcone Lanas, Francisco Javier Upna; Sorolla Ayza, Mario Upna; Marqués, R. (AIP Publishing, 2003)   Artículo / Artikulua  OpenAccess
      In this letter, a planar left-handed propagating medium consisting of a coplanar waveguide (CPW) inductively coupled to split ring resonators (SRR) and periodically loaded with narrow metallic wires is proposed. The wires ...
    • State-of-charge-based droop control for stand-alone AC supply systems with distributed energy storage 

      Urtasun Erburu, Andoni Upna; Sanchis Gúrpide, Pablo Upna; Marroyo Palomo, Luis Upna (Elsevier, 2015)   Artículo / Artikulua  OpenAccess
      The droop method is an advantageous technique for stand-alone AC supply systems, allowing for power sharing among various inverters with no need for communication cables. However, in stand-alone systems with multiple ...