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In this work, we introduce the notion of dG-Choquet integral, which generalizes the discrete Choquet integral replacing, in the first place, the difference between inputs represented by closed subintervals of the unit interval [0,1] by a dissimilarity function; and we also replace the sum by more general appropriate functions. We show that particular cases of dG-Choquet integral are both the discrete Choquet integral and the d-Choquet integral. We define interval-valued fuzzy measures and we show how they can be used with dG-Choquet integrals to define an interval-valued discrete Choquet integral which is monotone with respect to admissible orders. We finally study the validity of this interval-valued Choquet integral by means of an illustrative example in a classification problem. © 2021 This work was supported in part by the Spanish Ministry of Science and Technology, under project PID2019-108392GB-I00 (AEI/10.13039/501100011033), by the project PJUPNA-1926 of the Public University of Navarre and by the project VEGA 1/0267/21 .

The measurement of response time in hypertext transfer protocol (HTTP) requests is the most basic proxy measurement method for evaluating web browsing quality. It is used in the research literature and in application performance measurement instruments. During the development of a website, response time is obtained from in-browser measurements. After the website has been deployed, network traffic is used to continuously monitor activity, and the measurement data are used for service management and planning. In this study, we evaluate the accuracy of the measurements obtained from network traffic by comparing them with the in-browser measurement of resource load time. We evaluate the response times for encrypted and clear-text requests in an emulated network environment, in a laboratory deployment equivalent to a data centre network, and accessing popular web sites on the public Internet. The accuracy for response time measurements obtained from network traffic is noticeable higher for Internet long distance paths than for lowdelay paths (below 20 ms round-trip). The overhead of traffic encryption in secure HTTP requests has a negative effect on measurement accuracy, and we find relative measurement errors higher than 70% when using network traffic to infer HTTP response times compared This work was supported by the Spanish State Agency of Research through project PID2019-104451RB-C22/AEI/10.13039/501100011033

This study proposes a novel measurement-based method to predict and model three-dimensional (3-D) path loss in indoor scenarios, which first regresses 28 GHz measurements via median path loss modeling and then includes ordinary Kriging to interpolate shadowing. The performance of this method is evaluated by investigating the spatial structure that follows shadowing through the semivariogram, covariance function, and correlogram as variography tools. It is shown that semivariogram outperforms the other statistics to describe shadowing spatial continuity in path loss modeling in terms of the mean absolute error. This work was supported by the National Council of Science and Technology CONACYT, through the student scholarship number 746015, under Project RTI2018-095499-B-C31, funded by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE).

Currently, inverter-based stand-alone microgrids are gaining interest due to the advantages of obtaining energy from renewable sources. To manage the operation, these microgrids include storage systems connected in par- allel to the PCC through electronic inverters that are controlled as voltage sources in order to support the fre- quency and voltage at the PCC. For the purpose of ensuring P and Q sharing among inverters and also the synchronization stability of the microgrid, droop control is widely used, achieving a satisfactory performance in normal operation. Nevertheless, in the presence of overloads or short-circuits, the inverters must limit the current for self-protection, thereby modifying the performance of the system that then becomes prone to suffer transient stability problems. In this paper, first the performance of the inverter-based stand-alone microgrids with the conventional P-f and Iact-f droops is analyzed, obtaining the stability boundaries during current limitation. In order to always ensure the synchronization stability of the system, this paper then proposes the G-f droop that consists in employing the equivalent conductance seen by each inverter for its frequency droop control. Furthermore, as this variable always correctly represents the inverter power angle, the system dynamics are not affected by the operating conditions. The theoretical results have been validated by means of simulation and Hardware-In-the-Loop results, showing the superior performance of the proposed G-f droop This work has been supported by the Spanish State Research Agency (AEI) under grant PID2019-110956RB-I00/AEI/ 10.13039/501100011033, and by the Public University of Navarre through a PhD scholarship. Open access funding provided by Public University of Navarre.

A new type of resonance in the development of sensors using long-range surface exciton polariton (LRSEP) phenomena has been coined: surface exciton plasmon resonance (SEPR). The resonance was obtained in the reflected spectrum of a Kretschmann-Raether setup with a two-coupled-interface structure composed of 412 nm magnesium fluoride and 50 nm chromium thin films. The roles of different parameters such as thicknesses of the films and the incidence angles have been simulated. Some preliminary experimental results show a promising performance with a shift of the resonance central wavelength with changes in the incidence angle of -136.52 nm/° and a sensitivity of 23,221 nm/refractive index unit. This research was funded by Agencia Estatal de Investigacion (PID2019-106231RB-I00, the Institute of Smart Cities PhD Students grantes, the Ministry of Science, Innovation and Universities of Spain (FPU18/03087) and Margarita Salas-UPNA program (funded by the European Union-NextGenerationEU).

In this work a new multiparameter sensor platform based on lossy mode resonances is presented. The structure consists of a soda-lime optical slab waveguide butt-coupled to multimode optical fibers. A variable thickness thin-film is deposited to generate multiple independent resonances on the same waveguide, which can be monitored using a single spectrometer. In order to show the potentiality of the structure, a broad resonance was selectively narrowed by etching sections of the LMR producer thin film. The spectral width is progressively reduced, allowing to selectively isolate independent resonances, which opens the path for multiple LMR generation in the same spectra in a multiparameter sensing platform. The experimental results were corroborated with a theoretical analysis based on the finite difference method (FDM). As a proof of concept, two refractometers on the same waveguide were fabricated and tested using PDMS cells. This platform can be easily miniaturized in order to integrate multiple sensors at low cost, what can be of interest for the development of multi-analyte biosensors probes. IEEE This work was supported in part by the Spanish Ministry of Economy and Competitiveness under Grant PID2019-106070RB-I00 and Grant PID2019-106231RB-I00.

In this brief, a novel pseudo-differential low-transconductance amplifier is proposed based on the bootstrapping technique. The transconductor is implemented using two voltage follower topologies as amplifiers with their outputs connected to both terminals of a resistor, thus bootstrapping the voltages at these terminals to increase the equivalent resistance value, and achieve a very low transconductance without the need for large passive components. In this way, a highly-linear compact structure is designed whose transconductance can be tuned by external current sources. The circuit was fabricated in a standard 0.18μm CMOS process. The experimental results show a tunable transconductance in the range of tens of nA/V, with a total harmonic distortion lower than -40dB at 350mVpp@1kHz. The power consumption of the amplifier is 4μW under a 1.8V supply voltage. This work was supported by CONACYT through the Doctoral Grant 467255 and the Research Project CONACYT CB-2015-257985

The increasing sophistication of wind turbine design and control generates a need for high-quality wind data. The relatively limited set of available measured wind data may be extended with computer generated data, for example, to make reliable statistical studies of energy production and mechanical loads. Here, a data-driven model for the generation of surrogate wind speeds is compared with two state-of-the-art time series models that can capture the probability distribution and the autocorrelation of the target wind data. The proposed model, based on the phase-randomised Fourier transform, can generate wind speed time series that possess the power spectral density of the target data and converge to their generally non-Gaussian probability distribution with an arbitrary, user-defined precision. The model performance is benchmarked in terms of probability distribution, power spectral density, autocorrelation, and nonstationarities such as the diurnal and seasonal variations of the target data. Comparisons show that the proposed model can outperform the selected models in reproducing the statistical descriptors of the input datasets and is able to capture the nonstationary diurnal and seasonal variations of the wind speed. This work was partly supported by the Research Foundation Flanders (FWO) [grant number 74213/K231719N].

Recently, new wireless communication systems within aircrafts cabins have drawn higher attention due to the growing demand of passenger services and applications and their corresponding requirements and constraints. In this regard, the fifth generation (5G) of wireless communication becomes an attractive and promising alternative to enable aircraft passengers' comfort and entertainment along the flight, considering its potential benefits in term of high data transfers and low latencies. Nevertheless, general population concern about radio frequency electromagnetic fields (RF-EMF) safety in general and, in particular to the environmental exposure at which we are all exposed in these flights, increases at the same time. Thus, in this work, we present an experimental campaign of measurements for current passengers' environmental exposure assessment, performed in different real generalizable type of flights and aircrafts' cabins, in order to provide current RF-EMF exposure insight within these complex heterogeneous environments. In addition, worst-case uplink 5G scenarios, where all 5G cellular handsets of the passengers operate at the same time, have been simulated by means of an in-house developed 3D Ray Launching (3D-RL) deterministic technique. Before takeoff and after landing, critical scenarios with the aircrafts' doors closed have been selected and assessed considering different types of modeled aircrafts full of passengers, considering 5G frequency range 2 (5G-FR2) operating links. The obtained results show that the operation frequency and the morphology and topology of the aircraft cabin have a great influence in the environmental RF-EMF passengers' spatial distribution and overall exposure, but not exceeding, even in worst case conditions, the international established regulatory limits. © 2022 IEEE. This work was supported by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE) under Project RTI2018-095499-B-C31.

Traditionally, to characterize the response of droop-controlled systems RMS models have been used. However, as it is demonstrated in this work, when droop control is applied to doubly-fed induction generators, RMS models do not allow to predict the system stability and dynamic response. Thus, in this article, a linearized small-signal model that overcomes the limitations of RMS models is presented. The proposed model is validated by simulation in MATLAB/Simulink demonstrating that it allows to accurately analyze the stability and dynamic response of the system under study. This model is an interesting tool that can be used in future works to design and adjust grid-forming controllers for doubly-fed induction generators. This work was supported by the Spanish State Research Agency (AEI) under Grant PID2019-110956RB-I00/AEI/10.13039.

In this article, a compact coplanar waveguide (CPW) technique based ultra-wideband multiple-input-multiple-output (MIMO) antenna is proposed. The design is characterized by a broad impedance bandwidth starting from 3 GHz to 11 GHz. The overall size of the MIMO design is $60\times60$ mm2 ( $1.24\times 1.24\,\,\lambda _{g}^{2}$ @ 3 GHz) with a thickness of 1.6 mm. To make the design ultra-wideband, the proposed MIMO antenna design has four jug-shaped radiating elements. The design is printed on a FR-4 substrate (relative permittivity of $\varepsilon _{r} = 4.4$ and loss tangent of $\mathrm {tan}\delta = 0.025$ ). The polarization diversity phenomenon is realized by placing four antenna elements orthogonally. This arrangement increases the isolation among the MIMO antenna elements. The simulated results of the ultra-wideband MIMO antenna are verified by measured results. The proposed MIMO antenna has a measured diversity gain greater than 9.98, envelope correlation coefficient (ECC) less than 0.02, and good MIMO performance where the isolation is more than -20dB between the elements. The group delay, channel capacity loss (CCL), and the total active reflection coefficient (TARC) multiplexing efficiency and mean effective gain results are also analyzed. The group delay is found to be less than 1.2ns, CCL values calculated to be less than 0.4 bits/sec/Hz, while the TARC is below -10dB for the whole operating spectrum. The proposed design is a perfect candidate for ultra-wideband wireless communication systems and portable devices. This work was supported in part by the Universidad Carlos III de Madrid and the European Union's Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Grant 801538, and in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE) under Grant RTI2018-095499-B-C31.

Doubly fed induction generators (DFIGs) with an LCL filter are widely used for wind power generation. In these energy conversion systems, there is an interaction between the grid-side converter (GSC) and the rotor-side converter (RSC) control loops, the generator and the LCL filter that must be properly modeled. Such interaction between the GSC and the RSC proves to have a significant influence on the stability. Several active damping (AD) methods for grid-connected converters with an LCL filter have been proposed, nevertheless, the application of these techniques to a DFIG wind turbine is not straightforward, as revealed in this article. To achieve a robust damping irrespective of the grid inductance, this article proposes an AD strategy based on the capacitor current feedback and the adjustment of the control delays to emulate a virtual impedance, in parallel with the filter capacitor, with a dominant resistive component in the range of possible resonance frequencies. This work also proves that, by applying the AD strategy in both converters simultaneously, the damping of the system resonant poles is maximized when a specific value of the grid inductance is considered. Experimental results show the interaction between the GSC and the RSC and validate the proposed AD strategy. © 1986-2012 IEEE. This work was supported by the Spanish State Research Agency (AEI) under Grant PID2019-110956RB-I00/AEI/10.13039.

In this work, a multi-parameter point sensor based on the combination of Fabry-Perot (FP) and the anti-resonant (AR) reflecting guidance in cascade configuration is proposed and experimentally demonstrated. This structure, based on FP interference and AR reflecting guidance, was fabricated with two different air micro-cavities. The attained experimental results showed different strain and temperature sensitivities for the antiresonance contribution. However, when analyzing the FP interference, only strain sensitivity was observed, demonstrating that this air micro-cavity was also insensitive to temperature variations. This work was supported by the Spanish AEI projects TEC2016-76021-C2 and PID2019-107270RB-C22, FEDER Funds, the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 838143, Projects for young researches UPNA 2019, “Caja Navarra” and “la Caixa” foundations under agreement LCF/PR/PR13/51080004 and the grant BGP18/00180 of the “Beatriz Galindo” programme from the Spanish Ministry of Science, Innovation and Universities.

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 wide range of learning areas, including health, social policy, and engineering, among others, not only in primary school but also in higher formal education. Using this methodology, the learning process becomes more stimulating while also reaching a competitive level in some circumstances. In the present work, the authors propose a new gamification strategy based on an escape-room in which all the puzzles to be passed are related to the area of optics and photonics and use readily available or low-cost equipment. The major field of application of this novel teaching strategy will be the practical section of a course, that is usually carried out in a laboratory, and will be aimed at both undergraduate and master's degree students. A coevaluation method is also proposed where the rest of the students will provide valuable feedback to each one of their colleagues and to the instructor. This research was funded by the Electric, Electronic and Communications Engineering Department of Public University of Navarre.

In this work, a very compact rectangular waveguide low-pass filter with meandered topology based on commensurate lines for Ku-band satellite applications is analysed for high-power handling capabilities. The device consists of rectangular waveguide sections properly cascaded to form a meandered topology to obtain the desired value of the local reflection coefficients. which are essential to achieve the target frequency response and also to keep large mechanical gaps. Hence, this technique allows us not only to design a filter with compact size but a filter geometry which is suitable for high power applications. In the paper, the low-pass filter based on commensurate lines is first designed by cascading E-plane mitered bends (±90° EMBs) in CST Microwave Studio (MWS) and then the values of the electromagnetic fields at the passband frequencies are exported to Spark3D to perform a multipactor analysis. The critical areas inside the device where the multipactor discharge occurs will also be identified in the high-power analysis., This work was supported by the Spanish Ministerio de Ciencia e Innovación –Agencia Estatal de Investigación (MCIN/AEI/ 10.13039/501100011033) under Project PID2020-112545RB-C53 and by the European Union's Horizon 2020 Research and Innovation Program under Grant 811232-TESLA-H2020-MSCA-ITN-2018.

Los sensores de fibra óptica han experimentado un importante progreso en los últimos años con el empleo de estructuras basadas en redes de Bragg, interferómetros o resonancias electromagnéticas, entre otras y el desarrollo de la nanotecnología, que ha permitido la deposición de recubrimientos a nivel micro y nanométrico sobre la fibra. Estos avances han posibilitado la fabricación de sensores de fibra óptica para medir variables físicas, parámetros químicos o aplicaciones de biosensado. Esta tesis contribuye al análisis y optimización, tanto teórica como experimental, de diferentes configuraciones y estructuras en fibra óptica, aplicadas al desarrollo de sensores. En esta tesis se estudian varias estructuras, incluidas las Lossy Mode Resonances (LMRs) y redes en fibra óptica: FBGs (redes de Bragg en fibra), LPGs (redes de período largo en fibra) y TFBGs (redes de Bragg inclinadas en fibra). Las principales líneas de investigación que se presentan en esta tesis son la fabricación de dispositivos multisensores basados en LMRs y la mejora del fenómeno de la mode transition en redes de fibra óptica: LPGs en fibras con doble cladding y TFBGs. El elemento común entre ambas líneas de investigación es el empleo de películas delgadas de materiales de alto índice de refracción: óxido de estaño (SnO2), óxido de indio y estaño (ITO) y dióxido de titanio (TiO2). Los resultados mostrados en esta tesis revelan el potencial de combinar varias estructuras y/o fenómenos en fibras ópticas para mejorar el desempeño de los sensores de fibra óptica. Optical fiber sensors have experienced an important progress in recent years with the employment of structures based on gratings, interferometers or electromagnetic resonances, among others; and the development of nanotechnology, that has enabled the deposition of coatings at the micro- and nanometric level on the fiber. These advances have allowed the manufacture of optical fiber sensors for measuring physical variables, chemical parameters or biosensing applications. This thesis contributes to the analysis and optimization, both theoretical and experimental, of different configurations and structures in optical fiber, applied to the development of sensors. Several structures are studied in this thesis, including Lossy Mode Resonances (LMRs) and optical fiber gratings: FBGs (fiber Bragg gratings), LPGs (long period fiber gratings) and TFBGs (tilted fiber Bragg gratings). The main research lines that are presented in this thesis are the fabrication of multisensing devices based on LMRs and the enhancement of the mode transition in optical fiber gratings: LPGs in double clad fibers and TFBGs. The common element between both research lines is the employment of thin films of high refractive index materials: tin oxide (SnO2), indium tin oxide (ITO) and titanium dioxide (TiO2). The results shown in this thesis reveal the potential of combining several structures and/or phenomena in optical fibers to improve the performance of optical fiber sensors. El desarrollo de esta tesis ha sido posible gracias al apoyo financiero del Ministerio de Universidades (beca FPU18/03087), el Ministerio de Ciencia e Innovación (PID2019-106231RB-I00 TEC), el Fondo Europeo de Desarrollo Regional (FEDER) (TEC2016-78047-R), la convocatoria ATTRACT financiada por el programa de investigación e innovación Horizon 2020 de la Unión Europea (subvención No 777222) y la Universidad Pública de Navarra (PJUPNA26). Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011) Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)

Modeling quantum interference in the presence of dissipation is a critical aspect of quantum technologies. Including dissipation into the model of a linear device enables for assessing the detrimental impact of photon loss, as well as for studying dissipation-driven quantum state transformations. However, establishing the input-output relations characterizing quantum interference at a general lossy N-port network poses important theoretical challenges. Here, we propose a general procedure based on the singular value decomposition (SVD), which allows for the efficient calculation of the input-output relations for any arbitrary lossy linear device. In addition, we show how the SVD provides an intuitive description of the principle of operation of linear optical devices. We illustrate the applicability of our method by evaluating the input-output relations of popular reciprocal and nonreciprocal lossy linear devices, including devices with singular and nilpotent scattering matrices. Our method also enables the analysis of quantum interference in large lossy networks, as we exemplify with the study of an N-port epsilon-near-zero (ENZ) hub. We expect that our procedure will motivate future research on quantum interference in complex devices, as well as the realistic modelling of photon loss in linear lossy devices. H2020 European Research Council (ERC Starting Grant 948504); Ministerio de Ciencia, Innovación y Universidades (MCIU) (RTI2018-093714-301J-I00, RYC2018-024123-I).

A design technique to include multiple and fully-controlled transmission zeros (TZs) in the frequency response of rectangular waveguide commensurate-line stepped-impedance filters is presented in this letter. These bandpass filters (BPFs) are known for having reduced sensitivities against manufacturing inaccuracies and are composed of multiple waveguide sections. In order to improve their selectivity, 3λg/4 and λg/4-stubs are included to create multiple TZs around the passband. The proposed technique allows us to add multiple stubs in a single section and, therefore, only minor adjustments in the affected part of the filter are required, which simplifies the overall design process. The technique has been verified with a design example with four TZs (two on each side) near the passband. This work was supported by the Spanish Ministerio de Ciencia e Innovación –Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033) under Project PID2020-112545RB-C53 and by the European Union’s Horizon 2020 Research and Innovation Program under Grant 811232-TESLA-H2020-MSCA-ITN-2018.

Nowadays, the reuse of electric vehicle batteries is considered to be a feasible alternative to recycling, as it allows them to benefit from their remaining energy capacity and to enlarge their lifetime. Stationary applications, such as self-consumption or off-grid systems support, are examples of second-life (SL) uses for retired batteries. However, reused modules that compose these batteries have heterogeneous properties, which limit their performance. This article aims to assess the influence of degradation in modules from electric vehicles, covering three main aspects: performance, capacity dispersion, and extended SL behavior. First, a complete characterization of new and reused modules is carried out, considering three temperatures and three discharge rates. In the second stage, intra- and intermodule capacity dispersions are evaluated with new and reused samples. Finally, the behavior during SL is also analyzed, through an accelerated cycling test so that the evolution of capacity and dispersion are assessed. Experimental results show that the performance of reused modules is especially undermined at low temperatures and high current rates, as well as in advanced stages of aging. The intramodule dispersion is found to be similar in reused and new samples, while the intermodule differences are nearly four times greater in SL. This work was supported in part by the Spanish State Research Agency (AEI) under Grant PID2019-111262RB-I00/AEI/10.13039/501100011033 and Grant DPI2016-80641-R, in part by the European Union under the H2020 Project STARDUST under Grant 774094, in part by the Government of Navarra under Research Project 0011-1411-2018-000029 GERA, and in part by the Public University of Navarre under Project ReBMS PJUPNA1904.

This work presents a dual-wavelength C-band erbium-doped fiber laser assisted by an artificial backscatter reflector. This fiber-based reflector, inscribed by femtosecond laser direct writing, was fabricated into a single mode fiber with a length of 32 mm. The dual-wavelength laser obtained, centered at 1527.7 nm and 1530.81 nm, showed an optical signal-to-noise ratio over 46 dB when pumped at 150 mW. Another feature of this laser was that the power difference between the two channels was just 0.02 dB, regardless of the pump power, resulting in a dual emission laser with high equalization. On the other hand, an output power level and a central wavelength instability as low as 0.3 dB and 0.01 nm were measured, in this order for both channels. Moreover, the threshold pump power was 40 mW. Finally, the performance of this dual-wavelength fiber laser enhanced with a random reflector for sensing applications was studied, achieving the simultaneous measurement of strain and temperature with sensitivities around 1 pm/µε and 9.29 pm/°C, respectively. This work is part of the projects PID2019-107270RB, funded by MCIN/AEI/10.13039/ 501100011033 and FEDER 'A way to make Europe', and PDC2021-121172 funded by MCIN/AEI/10.13039/ 501100011033 and European Union 'Next generation EU'/PTR, the Ministerio de Educación, Cultura y Deporte of Spain (PhD grant FPU2018/02797).

The Internet of Things (IoT) based real-time health monitoring system has contributed towards a brilliant human welfare both in urban and rural areas. Many of such solutions are not well applicable in developing countries like Bangladesh due to lack of uninterrupted communication system. In this paper, we present an IoT-based real-time health monitoring system that can measure, monitor and report people's health condition online and offline from anywhere. Our proposed IoT based solution is capable to transmit the sensitive health information to medical centres and caregivers in real time. The proposed system has been designed with Arduino UNO, Nodemcu, and Global System for Mobile Communication (GSM) modules to measure body temperature, pulse rate, Oxygen saturation, room temperature, and air quality in a smart home setting. The system can also provide the patient's historical health records. Our implementation was tested on some test cases which works excellent with accuracy. The proposed system has high potentiality for the rural and urban areas in developing countries. Dr. Mohammad Alibakhshikenari and Dr. Farhad Arpanaei acknowledge support from the CONEX-Plus programme funded by Universidad Carlos III de Madrid and the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 801538. Also, this work was supported, in part, by Project RTI2018-095499-B-C31, funded by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE), in part, by a Foreign Expert Exchange Project from the Minister of Science and Technology (grant no.: G2021171024L) and in part, by Project PCNNo.IC20201325, funded by Bangladesh Bureau of Educational Information & Statistics (BANBEIS), Ministry of Education, Government of the People’s Republic of Bangladesh.

To date, the novel Coronavirus (SARS-CoV-2) has infected millions and has caused the deaths of thousands of people around the world. At the moment, five antibodies, two from China, two from the U.S., and one from the UK, have already been widely utilized and numerous vaccines are under the trail process. In order to reach herd immunity, around 70% of the population would need to be inoculated. It may take several years to hinder the spread of SARS-CoV-2. Governments and concerned authorities have taken stringent measurements such as enforcing partial, complete, or smart lockdowns, building temporary medical facilities, advocating social distancing, and mandating masks in public as well as setting up awareness campaigns. Furthermore, there have been massive efforts in various research areas and a wide variety of tools, technologies and techniques have been explored and developed to combat the war against this pandemic. Interestingly, machine learning (ML) algorithms and internet of Things (IoTs) technology are the pioneers in this race. Up till now, several real-time and intelligent IoT-based COVID-19 diagnosing, and monitoring systems have been proposed to tackle the pandemic. In this article we have analyzed a wide range of IoTs technologies which can be used in diagnosing and monitoring the infected individuals and hotspot areas. Furthermore, we identify the challenges and also provide our vision about the future research on COVID-19. Dr. Mohammad Alibakhshikenari acknowledges support from the CONEX-Plus programme funded by Universidad Carlos III de Madrid and the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 801538. Additionally, this work was supported by Project RTI2018-095499-B-C31, funded by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE).

With the goal of ultimate control over the light propagation, photonic crystals currently represent the primary building blocks for novel nanophotonic devices. Bloch surface waves (BSWs) in periodic dielectric multilayer structures with a surface defect is a well-known phenomenon, which implies new opportunities for controlling the light propagation and has many applications in the physical and biological science. However, most of the reported structures based on BSWs require depositing a large number of alternating layers or exploiting a large refractive index (RI) contrast between the materials constituting the multilayer structure, thereby increasing the complexity and costs of manufacturing. The combination of fiber–optic-based platforms with nanotechnology is opening the opportunity for the development of high-performance photonic devices that enhance the light-matter interaction in a strong way compared to other optical platforms. Here, we report a BSW-supporting platform that uses geometrically modified commercial optical fibers such as D-shaped optical fibers, where a few-layer structure is deposited on its flat surface using metal oxides with a moderate difference in RI. In this novel fiber optic platform, BSWs are excited through the evanescent field of the core-guided fundamental mode, which indicates that the structure proposed here can be used as a sensing probe, along with other intrinsic properties of fiber optic sensors, as lightness, multiplexing capacity and easiness of integration in an optical network. As a demonstration, fiber optic BSW excitation is shown to be suitable for measuring RI variations. The designed structure is easy to manufacture and could be adapted to a wide range of applications in the fields of telecommunications, environment, health, and material characterization. Fundación para la Promoción de la Investigación y la Tecnología-Banco de la República of Colombia (Contract 202103); Universidad Nacional de Colombia (Hermes code 46509); Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (TEC2016-78047-R and PID2019-106231RB-I00). E.G.V. acknowledges the support of COLCIENCIAS through the Doctoral Scholarship program.

In order to provide interactive capabilities within the context of Internet of Thing (IoT) applications, wireless communication systems play a key role, owing to in-herent mobility, ubiquity and ease of deployment. However, to comply with Quality of Service (QoS) and Quality of Experience (QoE) metrics, coverage/capacity analysis must be performed, to account for the impact of signal blockage as well as multiple interference sources. This analysis is especially complex in the case of indoor scenarios, such as those derived from Industrial Internet of Things (IIoT). In this work, a fully volumetric approach based on hybrid deterministic 3D Ray Launching is employed providing precise wireless channel characterization and hence, system level analysis of indoor scenarios. Coverage/capacity, interference mapping and time domain characterization estimations will be derived, considering different frequencies of operation below 6 GHz. The proposed methodology will be tested against a real measurement scenario, providing full flexibility and scalability for adoption in a wide range of IIoT capable environments. Open Access funding provided by Universidad Pública de Navarra. This work was supported by the European Union’s Horizon 2020 research and Innovation programme under grant agreement N°774094 (Stardust-Holistic and Integrated Urban Model for Smart Cities) and by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (Agencia Estatal de Investigación, Fondo Europeo de Desarrollo Regional -FEDER-, European Union) under the research grant RTI2018-095499-B-C31 IoTrain.

The development of resonance phenomena-based optical biosensors has gained relevance in recent years due to the excellent optical fiber properties and progress in the research on materials and techniques that allow resonance generation. However, for lossy mode resonance (LMR)-based sensors, the optical fiber presents disadvantages, such as the need for splicing the sensor head and the complex polarization control. To avoid these issues, planar waveguides such as coverslips are easier to handle, cost-effective, and more robust structures. In this work, a microfluidic LMR-based planar waveguide platform was proposed, and its use for biosensing applications was evaluated by detecting anti-immunoglobulin G (anti-IgG). In order to generate the wavelength resonance, the sensor surface was coated with a titanium dioxide (TiO2) thin-film. IgG antibodies were immobilized by covalent binding, and the detection assay was carried out by injecting anti-IgG in PBS buffer solutions from 5 to 20 μg/mL. The LMR wavelength shifted to higher values when increasing the analyte concentration, which means that the proposed system was able to detect the IgG/anti-IgG binding. The calibration curve was built from the experimental data obtained in three repetitions of the assay. In this way, a prototype of an LMR-based biosensing microfluidic platform developed on planar substrates was obtained for the first time This research was funded by the Spanish Agencia Estatal de Investigacion (AEI) with reference PID2019-106231RB-I00 and also by the Public University of Navarra, with the project BIOFOCEL (ref. PJUPNA2033) and a pre-doctoral research grant.

Space Systems have been historically characterised by high performance, high reliability and high cost. Every new generation of space systems tends to improve performance, keep as much as possible reliability, speeding the lead time and lower the cost. Aggressive approach is nowadays followed by some of the players of the new space ecosystem where, for instance, reli- ability can be relaxed thanks for the in-orbit redundancy or robustness to failures by having a constellation with a high number of satellites. This push towards the technology and system limit requires to investigate new methods for the manufacturing of RF/Microwave parts. RF devices such as those based on waveguide structures, benefit from an additive manufacturing approach in terms of radio frequency (RF) performance and compactness. However each manufacturing approach comes with specific features and limitations which need to be well understood and, in some cases, even taking advantage of them. This paper provides a short review of some of the RF/Microwave parts already manufactured using this technology. The paper will focus mainly on metal 3D printing parts since this technology is, at the moment, well accepted by the space community. UPNA thanks the support of the Spanish Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación (MCIN/AEI/ 10.13039/501100011033) under Project PID2020-112545RB-C53.

In this work, a novel optical fiber sensor capable of measuring both the liquid level and its refractive index is designed, manufactured and demonstrated through simulations and experimentally. For this, a silica capillary hollow-core fiber is used. The fiber, with a sensing length of 1.55 mm, has been processed with a femtosecond laser, so that it incorporates four holes in its structure. In this way, the liquid enters the air core, and it is possible to perform the sensing through the Fabry-Perot cavities that the liquid generates. The detection mode is in reflection. With a resolution of 4 μm (liquid level), it is in the state of the art of this type of sensor. The system is designed so that in the future it will be capable of measuring the level of immiscible liquids, that is, liquids that form stratified layers. It can be useful to determine the presence of impurities in tanks. This work was supported by the Ministerio de Economía y Competitividad of Spain (TEC2016-76021-C2-1-R and TEC2016-76021-C2-2-R), the FEDER/Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación (PID2019-107270RB-C21 and PID2019-107270RB-C22), the Ministerio de Educación, Cultura y Deporte of Spain (PhD grant FPU2018/02797), and Projects for young researches UPNA 2019. The authors also thank the INESC-Porto colleagues for the fiber sample used in the experiments.

The main objective of this work is to investigate the combinatory effects of both uniaxial magnetic and electrical anisotropies on the input impedance, resonant length and the mutual coupling between two dipoles printed on an anisotropic grounded substrate. Three different configurations: broadside, collinear and echelon are considered for the coupling investigation. The study is based on the numerical solution of the integral equation using the method of moments through the mathematical derivation of the appropriate Green’s functions in the spectral domain. In order to validate the computing method and evaluated MatlabⓇ calculation code, numerical results are compared with available literature treating particular cases of uniaxial electrical anisotropy; good agreements are observed. New results of dipole structures printed on uniaxial magnetic anisotropic substrates are presented and discussed, with the investigation of the combined electrical and magnetic anisotropies effect on the input impedance and mutual coupling for different geometrical configurations. The combined uniaxial (electric and magnetic) anisotropies provide additional degrees of freedom for the input impedance control and coupling reduction. This work was supported in part by the Electronic Components and Systems (ECSEL) Joint Undertaking, which is part of the POSITION-II Project under Grant Ecsel-7831132- Position-II-2017-IA, www.position-2.eu, in part by Fundação para a Ciência e a Tecnologia-Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MCTES) through National Funds and co-funded European Union (EU) Funds under Project UIDB/50008/2020-UIDP/50008/2020, in part by the General Directorate of Scientific Research and Technological Development (DGRSDT)-Ministry of Higher Education and Scientific Research (MESRS), Algeria, and in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI-Agencia Estatal de Investigación- al Fondo Europeo de Desarrollo Regional (AEI/FEDER), UE) under Grant RTI2018-095499-B-C31.

Photovoltaic (PV) conversion systems are in continuous development due to their increasingly competitive prices. The traditional configuration of large-scale PV plants is based on high-power central inverters, which have reduced their cost by increasing their power rating. However, this cost reduction is expected to saturate in the near future, mainly due to an increase in the cost of the dc wiring. Cascaded conversion systems have appeared as potential solutions to continue reducing the PV plant cost. They consist of several conversion units whose ac outputs are connected in series. This enables the power-rating reduction of each individual conversion unit, while maintaining the power rating of the conversion structure. Thus, the conversion units are placed closer to the PV panels, reducing the dc wiring cost. In this paper, a novel three-phase topology for medium-voltage cascaded conversion systems is presented. The proposed topology is formed of several conversion units, each one with a reduced number of conversion stages, namely, dc/ac, medium-frequency isolation and ac/ac. Moreover, thanks to its sequential operation and modulation technique, zero-voltage switching and zero-current switching are achieved in all conversion stages. In this way, with respect to the configuration with central inverters, the proposed topology has the advantages of cascaded conversion systems. In comparison to previously investigated cascaded topologies, the proposed topology also presents promising characteristics, representing a potential cost reduction and efficiency increase. An experimental validation of the topology is carried out in a laboratory prototype consisting of three conversion units. This work was supported in part by the Spanish State Research Agency (AEI) under Grant PID2019-110956RB-I00 /AEI/10.13039/501100011033, and in part by the Public University of Navarre through a Ph.D. Scholarship.

Inductors are cornerstone components in power electronics converters. Since winding loss is the dominant loss mechanism in these components, its accurate measurement is fundamental for the validation of the inductor’s operation and design. The techniques for the winding resistance $R_{w}$ measurement in power inductors can be classified into two groups, indirect and direct. Both techniques use coupled inductors to separate winding and core power losses. If coupled inductors with non-zero winding mutual resistances $R_{w,m}$ are used, invalid results are obtained with these techniques. Understanding the meaning of $R_{w,m}$ in coupled inductors is complex. In this paper, the impact of $R_{w,m}$ on the inductor $R_{w}$ measurement techniques is demonstrated and practical guidelines for the design of the zero $R_{w,m}$ coupled inductors are given. Particularly, the location of the auxiliary winding for the direct technique is investigated. In order to compare the $R_{w}$ measurement techniques and to validate the coupled inductor’s $R_{w,m}$ impact, two different inductors are built and tested. The results are compared with the values for $R_{w}$ calculated by FEA simulation. It is found that only the direct technique with an auxiliary winding carefully designed and located following the guidelines given in this paper makes the accurate measurement of $R_{w}$ in power inductors possible.

This paper presents a metasurface based multiple-input multiple-output (MIMO) antenna with a wideband operation for millimeter-wave 5G communication systems. The antenna system consists of four elements placed with a 90 degree shift in order to achieve a compact MIMO system while a 2×2 non-uniform metasurface (total four elements) is placed at the back of the MIMO configuration to improve the radiation characteristics of it. The overall size of the MIMO antenna is 24×24 mm 2 while the operational bandwidth of the proposed antenna system ranges from 23.5-29.4 GHz. The peak gain achieved by the proposed MIMO antenna is almost 7dB which is further improved up to 10.44 dB by employing a 2×2 metasurface. The total efficiency is also observed more than 80% across the operating band. Apart from this, the MIMO performance metrics such as envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CCL) are analyzed which demonstrate good characteristics. All the simulations of the proposed design are carried out in computer simulation technology (CST) software, and measured results reveal good agreement with the simulated one which make it a potential contender for the upcoming 5G communication systems. This work was supported in part by the Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant Agreement No 801538, and in part by the the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE) under Grant RTI2018-095499-B-C31.

The advent of Indsutrial Internet of Things is one of the main drivers for the implementation of Industry 4.0 scenarios and applications, in which wireless communication systems play a key role in terms of flexibility, mobility and deployment capabilities. However, the integration of wireless communication systems poses challenges, owing to variable path loss conditions and interference impact. In this work, an Ultra-Wideband (UWB) system for indoor location in very large, complex industrial scenarios is presented. Precise wireless channel characterization for the complete volume of a logistical plant is performed, based on 3D hybrid ray launching approximation, in order to aid network node design process. Wireless characterization, implementation and measurement results are obtained for both 4 GHz and 6 GHz frequency bands, considering different densities of scatterers within the scenario under test. Time domain estimation results have been obtained and compared with time of flight measurement results, showing good agreement. The proposed methodology enables to perform system design and performance tasks, analyzing the impact of variable object density conditions in wireless channel response, providing accurate time of flight estimations without the need of complex channel sounder systems, aiding in optimal system planning and implementation. This work was supported in part by the European Union’s Horizon 2020 Research and Innovation Programme (Stardust-Holistic and Integrated Urban Model for Smart Cities) under Grant 774094, in part by the Ministerio de Ciencia through the Innovación y Universidades, Gobierno de España (Agencia Estatal de Investigación, Fondo Europeo de Desarrollo Regional—FEDER, European Union) under Grant RTI2018-095499-B-C31 IoTrain, and in part by the Gobierno de Navarra-Departamento de Desarrollo Económico under Grant 0011-1365-2019-000097 OEE LOG.

In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, exhibits left-handed metamaterial characteristics. The matching network is first theoretically modelled to gain insight of its limitations. It was then implemented directly in the 50- Ω feedline to a standard circular patch antenna, which is an unconventional methodology. The antenna's performance was verified through measurements. With the proposed technique there is 2.7 dBi improvement in the antenna's radiation gain and 12% increase in the efficiency at the center frequency, and this is achieved over a significantly wider frequency range by a factor of approximately twenty. Moreover, there is good correlation between the theoretical model, method of moments simulation, and the measurement results. This work was supported in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE), under Grant RTI2018-095499-B-C31, in part by the British Council (UK-China-BRI Countries Education Partnership Initiative 2019), in part by the Innovation Programme under Grant H2020-MSCA-ITN-2016 SECRET-722424, and in part by the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/E022936/1.

For the controller design and stability analysis of power electronic converters, the Bode stability criterion and its subsequent revisions are the most practical tools. However, even though the control of the power converter is usually implemented in a microprocessor, none of these methods is infallible when applied to a discrete system. This article therefore proposes a new stability criterion, named the Discrete Generalized Bode Criterion (DGBC). This method is based on the Nyquist criterion but developed from the open-loop Bode diagram, evaluated also at 0 Hz and at the Nyquist frequency. The proposed criterion combines the advantages of the Nyquist and Bode criteria, since it is always applicable and provides an interesting and useful tool for the controller design process. The method is applied to design an active damping control of an inverter with LCL filter, showing how the proposed criterion accurately predicts stability, in contrast to the existing Bode criteria. The theoretical analysis is validated through experimental results performed with a three-phase inverter and an LCL filter. This work was supported in part by the Agencia Estatal de Investigación (AEI) under Grant PID2019-110956RB-I00/AEI/10.13039/501100011033, and in part by the Ingeteam Power Technology.

In this article, a compact printed monopole dual-band antenna using artificial magnetic conductor (AMC)-plane with improved gain and broader bandwidth, applicable for off-body internet of things (IoT) devices is presented. The monopole antenna consists of two C-shaped resonators connected through a U-shaped monopole, parasitic elements, discrete ground circular rings and a co-planar waveguide (CPW) feedline. Each artificial magnetic conductor (AMC) unit cell consists of a slotted circular and a square stubs, designed with two zero-crossing phases for improving the radiation characteristics and to achieve the high gain. The overall size of the proposed AMC-backed antenna is 44.4 mm ×44.4 mm ×1.6 mm with electrical dimensions of 0.75lambdag×0.75lambdag×0.027lambdag . This AMC-backed antenna featured measured bandwidths of 9.6% and 12.4% with improved measured gain values of 4.88 dB and 4.73 dB at 2.45 GHz and 5.8 GHz, respectively. The specific absorption rate (SAR) values are analysed and found to be 1.58 W/kg at 2.45 GHz and 0.9 W/kg at 5.8 GHz. Therefore, the proposed AMC-backed antenna is useful for off-body IoT devices operating at 2.45 and 5.8 GHz industrial, scientific, and medical (ISM) band applications. This work was supported in part by the Universidad Carlos III de Madrid; in part by the European Union's Horizon 2020 Research and Innovation Programme under Marie Sklodowska-Curie Grant 801538; in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER and UE) under Grant RTI2018-095499-B-C31; and in part by the Researchers Supporting Project, King Saud University, Riyadh, Saudi Arabia, under Project number RSP-2021/58.

Unconscious perceptions and decisions are influenced by gender bias. In this work, we provide an exhaustive data analysis of the Ph.D. theses defended in the field of optics and photonics in Spain by filtering key descriptors and gender. Our results show a severe underrepresentation of women in the Ph.D. stage in the optics community, which becomes even more prominent in technological and theoretical domains. The gender gap is reduced in biomedical and visual optics. This asymmetry is a symptom of gender bias in science associated with traditional stereotypes about health and social care. Further studies and measures are required in specific areas of science to eradicate implicit gender-based associations in scientific disciplines.

In an active motor unit (MU), the time intervals between the firings of its muscle fibers vary across successive MU activations. This variability is called jitter and is increased in pathological processes that affect the neuromuscular junctions or terminal axonal segments of MUs. Traditionally, jitter has been measured using single fiber electrodes (SFEs) and a difficult and subjective manual technique. SFEs are expensive and reused, implying a potential risk of patient infection; so, they are being gradually substituted by safer, disposable, concentric needle electrodes (CNEs). As CNEs are larger, voltage contributions from individual fibers of a MU are more difficult to detect, making jitter measurement more difficult. This paper presents an automatic method to estimate jitter from trains of motor unit potentials (MUPs), for both SFE and CNE records. For a MUP train, segments of MUPs generated by single muscle fibers (SF MUP segments) are found and jitter is measured between pairs of these segments. Segments whose estimated jitter values are not reliable, according to several SF MUP segment characteristics, are excluded. The method has been tested in several simulation studies that use mathematical models of muscle fiber potentials. The results are very satisfactory in terms of jitter estimation error (less than 10% in most of the cases studied) and mean number of valid jitter estimates obtained per simulated train (greater than 1.0 in many of the cases and less than 0.5 only in the most complicated). A preliminary study with real signals was also performed, using 19 MUP trains from 3 neuropathic patients. Jitter measurements obtained by the automatic method were compared with those extracted from a commercial system (Keypoint) and the edition and supervision of an expert electromyographer. From these measurements 63% were taken from equivalent interval pair sites within the time span of the MUP trains and, as such, were considered as compatible measurements. Differences in jitter of these compatible measurements were very low (mean value of 1.3 μs, mean of absolute differences of 2.97 μs, 25% and 75% percentile intervals of − 0.85 and 3.82 μs, respectively). Although new tests with larger number of real recordings are still required, the method seems promising for clinical practice. This work has been supported by the Spanish Ministry of Science, Education, and Universities, under the “Salvador de Madariaga” 2018 Program and by the Spanish Ministry of Education and Research, under the PID2019-109062RB-I00 project. Open Access funding provided by the Public University of Navarra.

A planar waveguide consisting of a coverslip for a microscope glass slide was deposited in one of its two faces with two materials: silver and indium tin oxide (ITO). The incidence of light by the edge of the coverslip permitted the generation of both surface plasmon and lossy mode resonances (SPRs and LMRs) in the same transmission spectrum with a single optical source and detector. This proves the ability of this optical platform to be used as a benchmark for comparing different optical phenomena generated by both metal and dielectric materials, which can be used to progress in the assessment of different sensing technologies. Here the SPR and the LMR were compared in terms of sensitivity to refractive index and figure of merit (FoM), at the same time it was demonstrated that both resonances can operate independently when silver and ITO coated regions are surrounded by different refractive index liquids. The results were supported with numerical results that confirm the experimental ones. The authors would like to acknowledge the partial support to the Agencia Estatal de Investigacion (AEI) PID2019-106070RB-I00 and PID2019-106231RB-I00 research funds, and the predoctoral research grants of the Public University of Navarra.

El estudio del nanoensamblado de nanopartículas metálicas sobre fibra ópticaha contribuido al desarrollo de sensores con mayor sensibilidad y eficiencia. Las aplicaciones que se pueden obtener en este campo pueden variar en función de ciertos parámetros como el tipo de nanopartícula metálica, ruta de síntesis, set-up o técnica de nanoensamblado. Esta tesis se centra en la síntesis de nanopartículas metálicas de oro (AuNPs) y plata (AgNPs) y su posterior nanoensamblado en películas delgadas usando las técnicas Layer-by-Layer Embedding (LbL-E) y el proceso de In-Situ Synthesis (ISS), para el desarrollo de sensores de fibra óptica. Este trabajo se encuentra dividido en tres bloques,el primero se centra en el uso de la técnica LbL-E para el desarrollo de sensores plasmónicos de fibra óptica para la detección de parámetros químicos. En segundo lugar, la técnica ISS se ha utilizado como alternativa parala fabricación de un nuevo dispositivo sensor de humedad basado en una cavidad interferométrica de Fabry-Perot en puntade una fibra óptica. Por último, se compara los efectos sobre la sensibilidad de los Tilted Fiber Bragg Grating (TFBG) al índice de refracción externo al utilizar ambas técnicas (ISS y LbL-E) para el nanoensamblaje de AuNPs. The study of the nanoassembly of metallic nanoparticles on optical fiber has contributed to the development of sensors with greater sensitivity and efficiency. The applications that can be obtained in this field may vary depending on certain parameters such as the type of metallic nanoparticle, synthesis route, set-up or nanoassembly technique. This thesis focuses on the synthesis of metallic gold (AuNPs) and silver (AgNPs) nanoparticles and their subsequent nanoassembly in thin films using Layer-by-Layer Embedding (LbL-E) technique and the In-Situ synthesis (ISS) process, for the development of fiber optic sensors. This work is divided into three blocks. The first focuses on using the LbL-E technique to develop fiber optic plasmonic sensors for the detection of chemical parameters. Secondly, the ISS technique has been used as an alternative for fabricating a new humidity sensor device based on a Fabry-Perot interferometric cavity at the end of an optical fiber. Finally, the effects on the sensitivity of Tilted Fiber Bragg Gratings to the external refractive index when using both techniques (ISS and LbL-E) for the nanoassembly of AuNPs are compared. The development of this work has been possible thanks to the Public University of Navarre (UPNA) and by the sponsoring of the Spanish Agencia Estatal de Investigación (AEI) and the European Regional Development Fund (ERDF) under the Projects TEC2016-79367-C2-2-R and PID2019-106070RB-I00. Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011) Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)

Achieving strong coupling between light and matter excitations in hybrid systems is a benchmark for the implementation of quantum technologies. We recently proposed [arXiv:2110.02984] that strong single-particle coupling between magnons and light can be realized in a magnetized epsilon-near-zero (ENZ) medium, in which magneto-optical effects are enhanced. Here we present a detailed derivation of the magnon-photon coupling Hamiltonian in dispersive media both for degenerate and non-degenerate optical modes, and show the enhancement of the coupling near the ENZ frequency. Moreover, we show that the coupling of magnons to plane-wave non-degenerate Voigt modes vanishes at specific frequencies due to polarization selection rules tuned by dispersion. Finally, we present specific results using a Lorentz dispersion model. Our results pave the way for the design of dispersive optomagnonic systems, providing a general theoretical framework for describing engineering ENZ-based optomagnonic systems., 20 pages, 8 figures

La crisis medioambiental actual está potenciando el aumento de la demanda de fuentes renovables y sistemas de almacenamiento. La conexión de estas unidades de generación, que se realiza a través de inversores de alta potencia para minimizar costes, está causando el reemplazo completo de los generadores síncronos, dando lugar a que aparezcan más frecuentemente microrredes basadas en inversores de alta potencia que pueden operar conectadas a red, aisladas o en ambos modos. En este escenario, los inversores electrónicos ya no pueden ser controlados en modo grid-following, ya que su funcionamiento como fuentes de corriente podría comprometer la estabilidad del sistema de potencia. Para evitar esto, se ha propuesto controlar los inversores en modo grid-forming, de forma que se comporten como fuentes de tensión, contribuyendo siempre al mantenimiento de la frecuencia y la tensión y siendo capaces de operar de forma aislada. Esta tesis se centra en el desarrollo de estrategias de control grid-forming para inversores de alta potencia. El principal objetivo es diseñar e implementar técnicas que permitan garantizar la operación fiable de los inversores grid-forming en cualquier condición. Por ello, se han abordado los siguientes aspectos: • Modelado del amortiguamiento intrínseco de inversores de alta potencia para diseñar los lazos de control de forma robusta. • Desarrollo de un método que proporcione al control de tensión basado en un único lazo, generalmente implementado en inversores de alta potencia, capacidad para limitar sobrecorrientes. • Análisis de estabilidad de una microrred basada en inversores cuando se utiliza el control droop como estrategia grid-forming. • Diseño de un control droop de frecuencia que garantice la estabilidad transitoria de la microgrid en presencia de sobrecargas y cortocircuitos. • Diseño de un control droop de frecuencia que mejore la estabilidad transitoria de los inversores grid-forming durante huecos de tensión. The present environmental crisis is driving the increase in demand for renewable sources and energy storage systems. The connection of these generation units, made through high-power inverters to minimize costs, is leading to the total replacement of synchronous generators, giving rise to the more frequent appearance of high-power inverter-based microgrids that can work tied to the main grid, islanded or in both operating modes. In this scenario, electronics inverters can no longer be controlled in grid-following mode since their performance as current sources would compromise the stability of the power systems. To avoid this, the concept of controlling the inverters in grid-forming mode has been proposed, in such a way that they perform as voltage sources, always contributing to the maintenance of frequency and voltage and having capability of working under stand-alone mode. This thesis aims to develop grid-forming control strategies for high-power inverters. The main objective is to design and implement techniques that permit ensuring the reliable operation of grid-forming inverters at all possible conditions. Therefore, the following issues are addressed: • Modeling of the inherent damping of high-power inverters to robustly design the control loops. • Development of a method that provides the single-loop voltage control, generally implemented in high-power inverters, with an overcurrent limiting capability. • Stability analysis of inverter-based microgrids when using the conventional droop control as grid-forming strategy. • Design of a frequency droop control that guarantees the transient stability of inverter-based microgrids in stand-alone mode in the presence of overloads or short-circuits. • Design of a frequency droop control that enhances the transient stability of grid-forming inverters in grid-connected mode under voltage dips. This thesis has been funded by the Public University of Navarre through a PhD scholarship. The company Ingeteam Power Technology has supported economically and technically this project under OTRI contracts 20200901027 and 2018901116. Moreover, the Spanish State Research Agency (AEI) and FEDER-UE have supported the investigation under grants PID2019-110956RB-I00 and DPI2016-80641-R. Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011) Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)

A high performance bulk-driven rail-to-rail fully differential buffer operating from ±0.3V supplies in 180 nm CMOS technology is reported. It has a differential–difference input stage and common mode feedback circuits implemented with no-tail, high CMRR bulk-driven pseudo-differential cells. It operates in subthreshold, has infinite input impedance, low output impedance (1.4 kΩ), 86.77 dB DC open-loop gain, 172.91 kHz bandwidth and 0.684 µWstatic power dissipation with a 50-pF load capacitance. The buffer has power efficient class AB operation, a small signal figure of merit FOMss = 12.69 MHzpFµW-1, a large signal figure of merit FOMls = 34.89 (V/µs) pFµW-1, CMRR = 102 dB, PSRR+ = 109 dB, PSRR- = 100 dB, 1.1 µV/√Hz input noise spectral density, 0.3 mVrms input noise and 3.5 mV input DC offset voltage. This research was partially funded by AEI/FEDER, grant number PID2019-107258RB-C31 and in part by the Andalusia Economy, Knowledge, Enterprise and University Council under Project P18-FR-4317.

Experimental aging studies are commonly conducted on lithium-ion batteries by full charge and discharge cycles. However, such profiles may differ from the actual operation of batteries in electric vehicles and stationary applications, where they are subjected to different partial charges and discharges. These partial cycles, which take place during a main charge or discharge process, are called micro-cycles if their depth of discharge is 1500. Nevertheless, if the number of deep cycles, disregarding micro-cycles, is the unit to measure battery use, then the degradation of cells with and without micro-cycles is similar. Based on this result, the number of cycles can be identified as a more accurate variable to measure the use of a cell, in comparison to charge throughput. This work is part of the projects PID2019-111262RB-I00, funded by MCIN/AEI/10.13039/501100011033/, STARDUST (774094), funded by European Union¿s Horizon 2020 research and innovation programme, HYBPLANT (0011-1411-2022-000039), funded by Government of Navarre, and a Ph.D. scholarship, funded by Public University of Navarre. Open access funding provided by Universidad Pública de Navarra.

In this paper, we present an analytical study for the investigation of the effects of the magnetoelectric elements of a reciprocal and nonreciprocal bianisotropic grounded substrate on the input impedance, resonant length of a dipole antenna as well as on the mutual coupling between two element printed dipole array in three configuration geometries: broadside, collinear and echelon printed on the same material. This study examines also the effect of the considered bianisotropic medium on the electric and magnetic field distributions that has been less addressed in the literature for antenna structures. Computations are based on the numerical resolution, using the spectral method of moments, of the integral equation developed through the mathematical derivation of the appropriate spectral Green"s functions of the studied dipole configuration. Original results, for chiral, achiral, Tellegen and general bi-anisotropic media cases, are obtained and discussed with the electric and magnetic field distributions for a better understanding and interpretation. These interesting results can serve as a stepping stone for further works to attract more attention to the reciprocal and non-reciprocal Tellgen media in-depth studies. This work is funded in part by: La Direction Générale de la Recherche Scientifique et du Développement Technologique (DGRSDT), Ministry of Higher Education and Scientific Research, Algeria, RTI2018-095499-B-C31, Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant 801538, Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE). Besides above, this work is also supported by the FCT/MEC through national funds and when applicable co-financed by the ERDF, under the PT2020 Partnership Agreement under the UID/EEA/50008/2019 project. This work is part of the POSITION-II project funded by the ECSEL joint Undertaking under Grant Number Ecsel-7831132-Postitio-II-2017-IA, www. posit ion-2. eu.

En este trabajo de tesis se muestra el estudio y diseño de sensores basados en el fenómeno de la resonancia de modos con pérdidas en configuración de guía de onda plana, lo que supone un complemento para la plataforma habitual, la fibra óptica. Sus ventajas son la simplicidad de manejo y la robustez de los dispositivos desarrollados. En este sentido, se ha diseñado, sobre la base de la deposición de óxido de cobre (CuO) como material generador de la resonancia, sensores de humedad y de respiración, y sobre la base de la deposición de óxido de tungsteno (WO3), sensores de índice de refracción y de compuestos orgánicos como el etanol, el metanol y la acetona. This thesis work shows the study and design of sensors based on the phenomenon of lossy mode resonance in a planar waveguide configuration, which is a complement to the usual platform, optical fiber. Its advantages are the simplicity of use and the robustness of the devices developed. In this sense, it has been designed, based on the deposition of copper oxide (CuO) as a resonance generating material, humidity and respiration sensors, and based on the deposition of tungsten oxide (WO3), sensors for refractive index and organic compounds such as ethanol, methanol and acetone. Fondo de investigación PID2019-106231RB-I00 de la Agencia Estatal de Investigación española (AEI). Beca de investigación predoctoral de la Universidad Pública de Navarra. Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011) Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)

Hospitals and healthcare centers are experiencing a remarkable implementation of new systems based on wireless communications technologies. Many of these systems provide location services and identification of materials, instrumentation and even patients, which promotes the increase of the quality and the efficiency of healthcare. A tracking system based on short-range radio frequency, UHF-RFID is evaluated. This system helps with location of orthopedic prosthesis according to the criteria and requirements of a specific hospital environment. It is characterized the influence of UHF-RFID system in the electromagnetic environment by measuring the parameters and characteristics of the emission levels. The results of the assessment are represented through 2D contour maps and simulations have been performed by means of an in-house 3D-RL algorithm. The proposed graph aims to provide a methodology of studying the electromagnetic environments and the evaluation of the safety conditions of workers, patients, and people in general. E field exposure levels due to the RFID localization system were analyzed in order to verify regulations concerning the safety of patients and the general public in the labor and healthcare fields. Localized electromagnetic field exposure at levels which may cause electromagnetic hazards in the specific healthcare environment have been found and potentially excessive exposure to EMF emitted by UHF RFID devices may apply to patients or bystanders. In all cases, insufficient electromagnetic immunity of electronic devices (including AIMD and other medical devices) should be considered and the electromagnetic hazards may be limited also by relevant preventive measures, as also shown in this paper, together with the principles of an in-situ evaluation of electromagnetic hazards near the UHF-RFID devices. This work was supported in part by the Instituto de Salud Carlos III Project 'Electromagnetic Characterization in Smart Environments of Healthcare, and Their Involvement in Personal, Occupational, and Environmental Health' under Grant PI14CIII/00056, and in part by the Sub-Directorate-General for Research Assessment and Promotion through the Project 'Metrics Development for Electromagnetic Safety Assessment in Healthcare Centers in the Context of 5G [(PI19CIII/00033) TMPY 508/19].'

In this paper, the assessment of multiple scenario cases for large-scale farm monitoring using Low-Power Wide-Area Network (LPWAN) based near-ground sensor nodes with the interaction of both tractors and farmers are presented. The proposed scenario under analysis considers multiple communication links, namely nodes to infrastructure, nodes to tractor, nodes to farmer, tractor to infrastructure and farmer to infrastructure communications. Moreover, these scenarios are proposed for tractors and agricultural equipment performance improvement and tracking, as well as resources management within the farm field. Different link type configurations are tested in order to consider the impact of ground, spatial distribution as well as infrastructure elements. The results show that LPWAN-based WSNs can provide better performance in terms of coverage and radio link quality results than ZigBee for a non-flat large-scale farm field in both cases of near-ground fixed nodes and moving tractor and farmer. The proposed systems are validated by cloud-based platforms for LoRaWAN, Sigfox and NB-IoT communications, providing flexible and scalable solutions to enable interactive farming applications. This research is supported by the 2017 Predoctoral Research Grant supported by the Xunta de Galicia and the research projects TEC2017-85529-C03-3R and RTI2018-095499-B-C31, funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU, AEI, FEDER, UE), as well as from European Union's Horizon 2020 research and Innovation programme under grant agreement N°774094 (Stardust-Holistic and Integrated Urban Model for Smart Cities).

En este trabajo de tesis se muestra el estudio y diseño de varias estructuras de guías de ondas ópticas. En los primeros capítulos se trabaja sobre configuraciones ya conocidas basadas en fibras monomodo – multimodo – monomodo (SMS) y LPFG a las que se les aplican técnicas de estrechamiento mediante ataque químico (etching) logrando el objetivo de mejorar parámetros como la sensibilidad. En el último capítulo se presenta una nueva estructura sensora basada en guías de ondas planas depositada con una o varias películas delgadas, con las que se pueden generar lossy mode resonances (LMRs), un fenómeno para el que se diferentes aspectos como: condiciones de deposición de la o las películas delgadas, sensibilidad de la estructura, materiales de deposición y optimización de la resonancia. This thesis shows the study and design of various optical waveguide structures. In the first chapters we work on already known configurations based on single-mode-multimode-singlemode fibers (SMS) and LPFG to which narrowing techniques are applied by chemical attack (etching), achieving the objective of improving parameters such as sensitivity. In the last chapter, a new sensor structure based on planar waveguides deposited with one or more thin films is presented, with which lossy mode resonances (LMRs) can be generated, a phenomenon for which different aspects were studied, such as: deposition conditions of the thin film(s), sensitivity of the structure, deposition materials and resonance optimization. Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011) Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)

OBJECTIVE: In adults, there is evidence that improvement of metabolic-associated fatty liver disease (MAFLD) depends on the reduction of myosteatosis. In children, in whom the prevalence of MAFLD is alarming, this muscle-liver crosstalk has not been tested. Therefore, we aimed to explore whether the effects of a multicomponent intervention on hepatic fat is mediated by changes in intermuscular abdominal adipose tissue (IMAAT) in children with overweight/obesity. RESEARCH DESIGN AND METHODS: A total of 116 children with overweight/obesity were allocated to a 22-week family-based lifestyle and psychoeducational intervention (control group, n = 57) or the same intervention plus supervised exercise (exercise group, n = 59). Hepatic fat percentage and IMAAT were acquired by MRI at baseline and at the end of the intervention. RESULTS: Changes in IMAAT explained 20.7% of the improvements in hepatic steatosis (P < 0.05). Only children who meaningfully reduced their IMAAT (i.e., responders) had improved hepatic steatosis at the end of the intervention (within-group analysis: responders -20% [P = 0.005] vs. nonresponders -1.5% [P = 0.803]). Between-group analysis showed greater reductions in favor of IMAAT responders compared with nonresponders (18.3% vs. 0.6%, P = 0.018), regardless of overall abdominal fat loss. CONCLUSIONS: The reduction of IMAAT plays a relevant role in the improvement of hepatic steatosis after a multicomponent intervention in children with overweight/obesity. Indeed, only children who achieved a meaningful reduction in IMAAT at the end of the intervention had a reduced percentage of hepatic fat independent of abdominal fat loss. Our findings suggest that abdominal muscle fat infiltration could be a therapeutic target for the treatment of MAFLD in childhood. This project was funded by the Spanish Ministry of Health's Fondos de Investigación Sanitaria del Instituto de Salud Carlos III (PI13/01335), the Spanish Ministry of the Economy Industry and Competitiveness (DEP2016-78377-R), and by European Regional Development Funds (ERDF): Una Manera de Hacer Europa. Support was also provided by the Regional Government of Navarra's Department of Economic Development (0011-1365-2019-000152 & 0011-1365-2020-000243), co-funded by European Regional Development Funds (ERDF 2014-2020 for Navarra). CC-S is supported by the Spanish Ministry of Science and Innovation (FJC2018-037925-I). MM is supported by Junta de Andalucía and European Union (SNGJ Ref-8025). MO is supported by the Spanish Ministry of Economy and Competitiveness (BES-2017-080770). This study was supported by the University of Granada Plan Propio de Investigación 2021 -Excellence actions: Unit of Excellence on Exercise, Nutrition and Health (UCEENS)- and the Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades, European Regional Development Funds (ref. SOMM17/6107/UGR).

El cambio en nuestro modelo de consumo y producción de energía es cada vez más urgente. Los problemas medioambientales, económicos y sociales relacionados con los combustibles fósiles han motivado la reacción gubernamental y ciudadana en búsqueda de soluciones alternativas. Así, la transición en el sector de la automoción hacia el vehículo eléctrico es ya una realidad. Las baterías de iones de litio son el corazón de los vehículos eléctricos, ya que posibilitan su autonomía y operación de forma similar a sus homólogos de combustión. No obstante, debido al uso, las características internas de estas baterías se degradadas, de tal modo que son retiradas cuando pierden en torno a un 30 % de capacidad energética. En los últimos años, la reutilización de estas baterías ha surgido como alternativa que permite aprovechar la capacidad energética remanente, alargando de este modo su vida útil. Aplicaciones estacionarias, como la integración de energías renovables o servicios de red, son consideradas como escenarios prometedores para estas baterías de segunda vida. Sin embargo, la viabilidad técnica y económica de estos sistemas de almacenamiento es hoy en día incierta. Esta tesis se centra en la viabilidad técnica de baterías de iones de litio de segunda vida provenientes de vehículos eléctricos. El estudio tiene un gran carácter experimental, utilizando para ello baterías reales que ya han finalizado su primera vida. Las principales líneas de trabajo de la tesis son: • Revisión del estado del arte actual de la segunda vida. • Caracterización del estado interno y análisis de la dispersión. • Estudio de la degradación y durabilidad en función del envejecimiento. • Mejora de la evaluación del estado interno, tanto en la etapa de reconfiguración como durante la operación de la segunda vida. • Estudio de la viabilidad técnica de un prototipo reconfigurado con módulosde segunda vida en distintas aplicaciones estacionarias. The transformation of our energy consumption and production model is increasingly urgent. Environmental, economic and social problems associated with fossil fuels have prompted the government and public reaction in the search for alternative solutions. Thus, the transition in the automotive sector towards an electric fleet is already a reality. Lithium-ion batteries are the core of electric vehicles, as they enable autonomy and operation in a similar way to their combustion counterparts. However, the performance features of these batteries degrade due to usage, in such a way that they are retired when their initial energy capacity fades by 30 %. The reuse of electric vehicle batteries has recently emerged as an alternative that allows benefiting from the remaining energy capacity, thus extending their lifetime. Stationary applications, such as the integration of renewable energies or the provision of grid services, are considered promising scenarios for these second-life batteries. Nevertheless, the technical and economic feasibility of these storage systems is currently uncertain. This thesis focuses on the technical feasibility of second-life lithium-ion batteries from electric vehicles. The study has a significant experimental approach, by using real batteries that have already ended their first life. The main work lines of the thesis are: • Revision of the existing state of the art on second-life batteries. • Characterisation of the internal state and analysis of dispersion. • Study of degradation and durability depending on ageing. • Improvement of the internal state assessment, both in the repurposing stage and during the second-life operation. • Study of the technical feasibility of a repurposed prototype with secondlife modules in different stationary applications. This thesis was awarded with public funding from a predoctoral scholarship of the Government of Navarre.; R&D national project, 'Design of optimal energy storage systems based on first and second-life lithium-ion batteries for the integration of renewable energies', DA2VIDA PID2019-111262RB-I00, Spanish Ministry of Economy, Industry and Competitiveness, 2020-2022; R&D national project, 'Hybridisation of advanced electricity storage systems in renewable-sources microgrids', HIBRITAER DPI2016-80642-R, Spanish Ministry of Economy, Industry and Competitiveness, 2016-2020; R&D Navarre Plan, 'Design and experimental validation of BMS for second-life lithium-ion batteries (ReBMS)', PJUPNA1904, Public University of Navarre (UPNA), 2020-2021. R&D Navarre Plan, 'Integration of renewable energy in the electric grid by means of advanced energy storage systems', GERA PI020 0011-1411-2018-000029, Government of Navarre, 2018-2020. Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011) Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa (ED 99/2011)