Comunicaciones y ponencias de congresos DIEE - IEES Biltzarretako komunikazioak eta txostenak

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Open Access
Robust and flexible design for effective low-pass filters exploiting a passband replica
(IEEE, 2024) Santiago Arriazu, David; Gómez Laso, Miguel Ángel; Lopetegui Beregaña, José María; Arregui Padilla, Iván; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
In this paper, a design approach for effective low-pass filters (LPF) that use the Rth-passband replica of the stepped-impedance prototype response is presented. Traditional LPF design methods often rely on well-established techniques, but they may not always deliver the desired performance or flexibility. By incorporating the Rth-passband replica of the stepped-impedance prototype, we introduce a new perspective that opens up new possibilities in filter design. This approach has the potential to overcome some of the limitations associated with existing methods, offering improved filter performance, robustness, and novel design possibilities and flexibility. Additionally, we will showcase its practical application by designing, fabricating, and measuring a 5th-order gap waveguide LPF that employs the first replica as per the provided guidelines.
Open Access
Magnetic human body communication based on double-inductor coupling
(IEEE, 2017) Hernández-Gómez, Yicely K.; Álvarez Botero, Germán Andrés; Bacca Rodríguez, Jan; Sousa, Fernando Rangel de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
This paper proposes a new technique for Human Body Communication (HBC) that uses the magnetic coupling in transmitter and receiver. A discussion about the presence of parasitic paths, when magnetic coupling is used in the transmitter, and electrical coupling is used in the receiver is presented; showing that the technique presented here, reduces the influence of the surrounding environment at the same time that simplifies the conventional reception schemes. In addition, a physical-based model is presented, obtaining a good model-experiment correlation up to 20 MHz. This results suggest the possibility to use the double-inductor coupling technique for the HBC channel characterization, contributing in the design of portable applications for communications systems.
Open Access
Optical fiber refractometers based on sputtered indium tin oxide coatings
(IEEE, 2011) López, S.; Ruiz Zamarreño, Carlos; Hernáez, M.; Del Villar, Ignacio; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
This work presents the fabrication of optical fiber refractometers based on indium tin oxide (ITO) coatings deposited by sputtering with response in the visible spectral region. ITO thin-films have been sputtered by employing a rotating mechanism that enables the fabrication of smooth and homogeneous coatings onto the optical fiber core. Fabricated ITO coated optical fiber devices present several resonances in the visible and near infrared region. These resonances show high optical power attenuations (more than 10 dB) in the visible spectral region, which produces changes in the colour of the output visible light. Therefore, since these resonances shift as a function of the refractive index (RI) of the surrounding medium it is feasible to determine the RI of the outer medium in contact with the ITO coating by simply monitoring the chromatic coordinates (colour change), x and y, of the visible output light
Open Access
SnO2 based optical fiber refractometers
(SPIE, 2012) Sánchez Zábal, Pedro; Ruiz Zamarreño, Carlos; Hernáez Sáenz de Zaitigui, Miguel; Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
In this work, the fabrication and characterization of refractometers based on lossy mode resonances (LMR) is presented. Tin dioxide (SnO2) films deposited on optical fibers are used as the LMR supporting coatings. These resonances shift to the red as a function of the external refractive index, enabling the fabrication of robust and highly reproducible wavelength-based optical fiber refractometers. The obtained SnO2-based refractometer shows an average sensitivity of 7198 nm/refractive index unit (RIU) in the range 1.333-1.420 RIU.
Open Access
Optical fiber refractometers based on indium tin oxide coatings with response in the visible spectral region
(Elsevier, 2011) Ruiz Zamarreño, Carlos; López, S.; Hernáez Sáenz de Zaitigui, Miguel; Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
This work presents the fabrication of optical fiber refractometers based on indium tin oxide (ITO) coatings with response in the visible spectral region. ITO thin-films have been sputtered by employing a rotating mechanism that enables the fabrication of smooth homogeneous coatings onto the optical fiber core. The ITO coated optical fiber devices present several resonances in the visible and infra-red region. These resonances show high optical power attenuations (more than 10 dB) in the visible spectral region, which produces changes in the colour of the output visible light. Therefore, since these resonances shift as a function of the surrounding medium refractive index (SMRI), it is feasible to determine the refractive index of the outer medium in contact with the ITO coating by simply monitoring the chromatic coordinates of the visible output light.
Open Access
Sensitivity enhancement by diameter reduction in low cutoff wavelength single-mode multimode singlemode (SMS) fiber sensors
(IEEE, 2017) Goñi Carnicero, Jaime; Del Villar, Ignacio; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Two different low cutoff wavelength single-mode fibers were used in single-mode multimode single-mode (SMS) configuration with the aim of designing sensors operating at short wavelengths, where optical sources and spectrometers are less expensive than in telecommunications bands. The diameter of the SMS structure was reduced with an etching process based on hydrofluoric acid immersion. The results prove that the devices can operate at wavelength ranges from 600 to 1200 nm and that multiple peaks can be obtained, each one with a different sensitivity that is proportional to the wavelength. Moreover, a fivefold increase in sensitivity to refractive index can be obtained. This high sensitivity indicates the possibility to apply this simple and cost-effective device in other applications such as biosensors or chemical sensors.
Open Access
All fiber interferometer for ice detection
(Optica Publishing Group, 2018) Arozarena Arana, Jesús Antonio; Socorro Leránoz, Abián Bentor; Del Villar, Ignacio; Díaz Lucas, Silvia; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC
This work presents an etched single-mode - multimode - single-mode structure that detects the solid-to-liquid change of state of the water due to an increased refractive index sensitivity within the 1.308 - 1.321 RIU range
Open Access
Fiber-optic immunosensor based on lossy mode resonances induced by indium tin oxide thin-films
(IEEE, 2017) Socorro Leránoz, Abián Bentor; Del Villar, Ignacio; Corres Sanz, Jesús María; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC
A novel immunosensor based on lossy mode resonances (LMRs) induced in optical fibers is developed in this contribution. Indium tin oxide (ITO) is sputtered on the optical substrate to generate an LMR in the transmission spectrum. Type G immunoglobulins (IgGs) are then attached to the ITO-coated fiber using (3-glycidyloxypropyl)trimethoxysilane (GPTMS). A phosphate buffer saline solution containing anti-IgGs is used to detect the biological reactions. The presented device is capable of detecting anti-IgG concentrations up to 10 nM. These results will permit the fabrication of biosensors based on a covalent attachment of bioreceptors over an LMR inducing thin-film.
Open Access
Towards personal privacy control
(Springer, 2007) Alcalde Bagüés, Susana; Zeidler, Andreas; Fernández Valdivielso, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper we address the realization of personal privacy control in the era of pervasive computing. How could an individual meet his/her expected level of privacy? how could the system guaranty that a user privacy criteria is fulfilled?. For that an elaborate set of requirements for personal privacy is given followed with the implementation of our SenTry policy language.
Open Access
Asymmetrically and symmetrically coated tapered optical fiber for sensing applications
(SPIE, 2015) Del Villar, Ignacio; Socorro Leránoz, Abián Bentor; Corres Sanz, Jesús María; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
The deposition of a non-metallic thin-film in a symmetrically coated tapered optical fiber leads to the generation of resonances due to guidance of a mode in the thin-film. At certain conditions, the resonances overlap each other, which can be avoided with an asymmetric coated tapered optical fiber, which permits to obtain resonances for TM and TE polarization separately. Numerical results showing the sensitivity to coating thickness and surrounding medium refractive index are also presented for both polarizations.
Open Access
A comparative study between SMS interferometers and lossy mode resonace optical fiber devices for sensing applications
(SPIE, 2015) Socorro Leránoz, Abián Bentor; Hernáez Sáenz de Zaitigui, Miguel; Del Villar, Ignacio; Corres Sanz, Jesús María; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Universidad Pública de Navarra / Nafaroako Unibertsitate Publikoa
Optical fiber sensors are of great interest due to their intrinsic advantages over electronic sensors. In this work, the sensing characteristics of two different and novel optical fiber devices are compared, after simultaneously depositing a thin-film using the layer-by-layer assembly deposition process. The first one is an SMS structure, formed by splicing two single-mode fiber pigtails on both sides of a coreless multimode fiber segment. This structure induces an interferometric phenomenon that generates several attenuation and transmission bands along the spectrum. These bands are sensitive to variations in the surrounding refractive index, although this sensitivity has been enhanced by a TiO2/PSS thin-film. The other device is a 40 mm uncladded segment of a 200 µm-core multimode optical fiber. When coated by a TiO2/PSS thinfilm, part of the light transmitted into the uncladded core is coupled into the thin-film, generating a lossy mode resonance (LMR). The absorption peaks due to these phenomena red-shift as long as the thin-film thickness increases or the external RI becomes higher. The performance of these devices as refractometers and relative humidity sensors are tested. Results show that the LMR-based sensor is more sensitive in both situations, in spite of its lower sensitivity. Particularly, it presents a 7-fold sensitivity enhancement when measuring surrounding medium refractive index changes and a 10-fold sensitivity enhancement when measuring environmental relative humidity. To our knowledge, this is the first time that a comparative study between SMS and LMR sensors is performed.
Open Access
A user-centric privacy framework for pervasive environments
(Springer, 2006) Alcalde Bagüés, Susana; Zeidler, Andreas; Fernández Valdivielso, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
One inherent feature of pervasive computing environments is the need to gather and process context information about real persons. Unfortunately, this unavoidably affects persons¿ privacy to a large degree. Each time today a citizen uses his cellular phone, his credit card or surf the web, he is leaving a trace that is stored for some reason. In a pervasive sensing environment, however, the amount of information collected is a) much larger than today and b) might be used to reconstruct personal information with great accuracy. The question we address in this paper is to control dissemination and flow of personal data across organizational, as well as personal boundaries, i.e., to potential addressees of privacy relevant information. This paper presents the User-Centric Privacy Framework (UCPF). It aims at protecting a user¿s privacy based on the enforcement of privacy preferences. They are expressed as a set of constraints over some set of context information. To achieve the goal of cross-boundary control, we introduce two novel abstractions, namely Transformations and Foreign Constraints, in order to extend the possibilities of a user to describe his privacy protection criteria beyond the current expressiveness ussually found today. Transformations are understood as any process that the user may define over a specific piece of context. This is a main building block for obfuscating or even plainly lie about the context in question. Foreign Constraints are an important complementing extension because they allow for modeling conditions defined on external users that are not the tracked individual, but may influence disclosure of personal data to third parties. We are confident that these two easy-to-use abstractions together with the general privacy framework presented in this paper constitute a strong contribution to the protection of the personal privacy in pervasive computing environments.
Open Access
Design of multi-layered radiative cooling structures using evolutionary algorithms
(IEEE, 2022) Lezaun Capdevila, Carlos; Jorajuria Gómez, Tania; Torres García, Alicia E.; Herrera, Pilar; Beruete Díaz, Miguel; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
In this work we present a novel way to design thinfilm radiative cooling metamaterials based on genetic algorithms. Three simulations with different design constraints have been done, resulting in three structures that achieve 39.96 W/m2 , 57.78 W/m2 and 61.77 W/m2 under direct sunlight, respectively. These structures are shorter than 5 µm of height and are composed of 9, 15 and 24 layers. This design method has the advantages of being automatable, needs fewer design experience in metamaterials and does not rely on commercial simulators. This work opens the path to an easy way of automated design of thin-film multi-layered devices for radiative cooling and other applications in the infrared range.
Open Access
Enhancing the infrared and visible emission properties of calcium silicate hydrate for radiative cooling using metamaterials
(IEEE, 2022) Lezaun Capdevila, Carlos; Dolado, J. S.; Torres García, Alicia E.; Pérez Escudero, José Manuel; Liberal Olleta, Íñigo; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Two periodic structures composed of metal cylinders with different orientations are used to improve the solar reflection of calcium silicate hydrate (CSH) while maintaining its atmospheric emission. Interesting effects have been found when the distance between bars is small, suggesting that lattice effects, arising from the interaction between the rods could be leveraged in the design of these metamaterials. The size of the metal bars is selected based on state of the art micro-manufacturing techniques. This study limits its scope to a CSH gel model; i.e. the most important component of cement-based materials. Further research will be undertaken to consider a best description of the dielectric function of concrete.
Open Access
Comparison of State-of-Charge estimation methods for stationary Lithium-ion batteries
(IEEE, 2016) Berrueta Irigoyen, Alberto; San Martín Biurrun, Idoia; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC
An accurate monitoring of the State of Charge (SoC) is mandatory for an efficient management of a Lithium-ion battery. Batteries of stationary systems barely have long resting periods when the cumulative errors can be reset. These special requirements make a robust and accurate SoC estimation algorithm necessary. A real stationary system including an experimental microgrid with renewable energy generation, home consumption and a 5.3 kWh Li-ion storage system is analyzed in this paper. Three representative SoC monitoring algorithms are applied and compared in terms of accuracy and robustness to battery aging and current measurement offset. A closed-loop method consisting of an adaptive filter and a state observer achieves best results while having a reasonable computational complexity.
Open Access
Control strategy for an integrated photovoltaic-battery system
(IEEE, 2017) Urtasun Erburu, Andoni; Sanchis Gúrpide, Pablo; Marroyo Palomo, Luis; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
In photovoltaic-battery systems, more attention is usually paid to the MPPT control while the battery management is put aside. This paper proposes two control strategies for an integrated PV-battery system, both of them making it possible to perform MPPT or regulate the battery voltage to its maximum value in order to prevent it from overcharging. Simulation results prove the feasibility of both controls.
Open Access
Comparison of linear and and small-signal models for inverter-based microgrids
(IEEE, 2014) Urtasun Erburu, Andoni; Sanchis Gúrpide, Pablo; Marroyo Palomo, Luis; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Frequency and voltage regulation in droop-based microgrids is generally modeled using small-signal analysis. In order to ensure accuracy, existing models do not decouple real and reactive power responses. However, the models become complicated and hide the real decoupled dynamics. This paper proposes a simple linear model which makes it possible to discern the different dynamic properties and to readily design the control parameters. The proposed model is validated by comparison with an accurate small-signal model and by simulation results. The effect of not considering the load is also evaluated.
Open Access
On the stability criteria for inverter current control loops with LCL output filters and varying grid impedance
(IEEE, 2017) Lumbreras Magallón, David; Barrios Rípodas, Ernesto; Ursúa Rubio, Alfredo; Marroyo Palomo, Luis; Sanchis Gúrpide, Pablo; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
The use of LC and LCL filters and grid impedance variations are creating new challenges on the controller design for current control loops of photovoltaic and wind turbine inverters. In the design process, stability criteria such as Bode and revised Bode are commonly used. This paper analyses the limitations of Bode and revised Bode criteria to reliably determine stability and proposes a sufficient and necessary stability criterion, based on the Nyquist criterion, but that makes use of the Bode diagram. The proposed criterion, named generalized Bode criterion, is always reliable and helps the controller design. Relative stability in complex control loops is also studied and a relative stability analysis is proposed. Finally, the generalized Bode criterion and the proposed relative stability analysis are illustrated with a practical example in which a PI is designed in order to guarantee stability and achieve relative stability.
Open Access
Hydrogen-lithium energy storage for a stand-alone microgrid
(2016) Berrueta Irigoyen, Alberto; San Martín Biurrun, Idoia; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
Sizing of the storage system for a stand-alone application: Satisfaction of technical requirements; Based on real data from an experimental microgrid; Long lifetime; Lowest price
Open Access
Lithium-ion battery model and experimental validation
(2015) Berrueta Irigoyen, Alberto; Irigaray, Víctor; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
A simple battery model is useful for: Sizing of the storage system for a particular application; Designing other elements connected to the battery; Managing the storage system operation. This poster consists on: Tests to characterize a lithium-ion battery at Ta=23 ⁰C. Methodology to fit the parameters of the battery model; Parameter trends related to the state of charge; Experimental validation and model accuracy.