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Carlosena García, Alfonso

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Carlosena García

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Alfonso

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0000-0002-7146-4043

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Now showing 1 - 10 of 29
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    PublicationOpen Access
    Sensing in coin discriminators
    (IEEE, 2007) Carlosena García, Alfonso; López Martín, Antonio; Arizti, Fernando; Martínez de Guereñu, Ane; Pina Insausti, José L.; García Sayés, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    This paper describes the technologies used in coin discriminator devices, stressing the improvements and novel mechanisms introduced by the authors in the past few years as a result of the cooperation with one leading company in the vending sector. Emphasis is put on how low-cost sensors are used to characterize coins (or tokens) and discriminate them from their counterfeits.
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    PublicationOpen Access
    Vibrato in singing voice: the link between source-filter and sinusoidal models
    (Springer Open, 2004) Carlosena García, Alfonso; Arroabarren Alemán, Ixone; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    The application of inverse filtering techniques for high-quality singing voice analysis/synthesis is discussed. In the context of source-filter models, inverse filtering provides a noninvasive method to extract the voice source, and thus to study voice quality. Although this approach is widely used in speech synthesis, this is not the case in singing voice. Several studies have proved that inverse filtering techniques fail in the case of singing voice, the reasons being unclear. In order to shed light on this problem, we will consider here an additional feature of singing voice, not present in speech: the vibrato. Vibrato has been traditionally studied by sinusoidal modeling. As an alternative, we will introduce here a novel noninteractive source filter model that incorporates the mechanisms of vibrato generation. This model will also allow the comparison of the results produced by inverse filtering techniques and by sinusoidal modeling, as they apply to singing voice and not to speech. In this way, the limitations of these conventional techniques, described in previous literature, will be explained. Both synthetic signals and singer recordings are used to validate and compare the techniques presented in the paper.
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    PublicationOpen Access
    Micropower class AB low-pass analog filter based on the super-source follower
    (IEEE, 2022) Martincorena Arraiza, Maite; Cruz Blas, Carlos Aristóteles de la; López Martín, Antonio; Carlosena García, Alfonso; Institute of Smart Cities - ISC
    An improved class AB version of the super source follower is used to implement a compact and power-efficient second order analog low-pass filter. The proposed circuit achieves a 41% power reduction as well as an improvement in linearity and pass band gain with respect to its class A counterpart. Measurement results of a test chip prototype fabricated in a 180 nm CMOS technology show a power consumption ranging from 50.3 μW to 85.27 μW for cutoff frequencies from 600 kHz to 890 kHz, with a supply voltage of ±0.75 V. A third order intermodulation distortion of −35.34 dB (for an input signal of 0.4 mV pp and 350 kHz) and a THD of −69.7 dB (for an input signal of 0.4 mV pp and 100 kHz) are measured, which results in an improvement with respect to the conventional class A version of 13.98 dB and 43.6 dB, respectively. The silicon area is 0.0592 mm 2 (using external capacitors).
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    PublicationOpen Access
    Design of low-cost smart accelerometers
    (Universitat Politècnica de Catalunya, 2005) Carlosena García, Alfonso; López Martín, Antonio; Massarotto, Marco; Cruz Blas, Carlos Aristóteles de la; Lecumberri Villamediana, Pablo; Gómez Fernández, Marisol; Pintor Borobia, Jesús María; Gárriz Sanz, Sergio; Ingeniería Eléctrica y Electrónica; Matemáticas; Ingeniería Mecánica, Energética y de Materiales; Ingeniaritza Elektrikoa eta Elektronikoa; Matematika; Mekanika, Energetika eta Materialen Ingeniaritza
    The goal of this project is to design a low-cost smart accelerometer, making use of a piezoelectric element as basic sensing material, and adding a mixed-mode conditioning circuit.
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    PublicationOpen Access
    Signal processing in ocean bottom seismographs for refraction seismology
    (IEEE, 2006) Rodríguez Barbarin, Iban; Mànuel Lázaro, Antonio; Carlosena García, Alfonso; Bermúdez, Antoni; Río, Joaquín del; Panahi, Shahram Shariat; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    This paper presents some experimental results on the application of signal processing techniques to underwater seismic signals. The novelty of this paper stems from the fact that it is the first paper, to the best of the author’s knowledge, dealing with a comprehensive processing of signals obtained from active refraction seismology. In particular, this paper has adapted known signal processing techniques to problems such as time of arrival detection (TOA), compression and representation through conventional images (hodocrones) used in underwater seismology. The work is part of a wider project aimed at the design of a small ocean bottom seismometer (OBS) undertaken by several research and development groups in Spain. This sophisticated easy to handle equipment allows recording useful active and passive seismicity information.
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    PublicationOpen Access
    Multichannel blind deconvolution of impulsive signals
    (2005) Lecumberri Villamediana, Pablo; Gómez Fernández, Marisol; Carlosena García, Alfonso; Matemáticas; Ingeniería Eléctrica y Electrónica; Matematika; Ingeniaritza Elektrikoa eta Elektronikoa
    In this communication, the problem of blind deconvolution of transient, impulsive signals in a multichannel environment is addressed. This kind of signals arise naturally, or are used as external excitation, in many mechanical and acoustical systems and can only be observed indirectly, after propagation through the medium. Blind deconvolution or identi cation methods published to date are not suitable for recovering these sources or the system response, as identi ability conditions are not met. We fully develop here a deterministic subspace method for the blind deconvolution in a multichannel environment which does not impose any restrictions on the excitation signals or on the impulse response of propagation channels, apart from nite length and channel diversity. The method is also extended to cope with signals in noisy environments.
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    PublicationOpen Access
    Ultra-low frequency multidirectional harvester for wind turbines
    (Elsevier, 2023) Castellano Aldave, Jesús Carlos; Carlosena García, Alfonso; Iriarte Goñi, Xabier; Plaza Puértolas, Aitor; Ingeniería; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    In this paper we propose, and demonstrate through a prototype, a completely novel device able to harvest mechanical energy from the multidirectional vibrations in a wind turbine, and convert it into electrical, to power autonomous sensors. The application is very challenging since vibrations are of ultra-low frequency, well below 1 Hz, with accelerations of tenths of cm/s2 (0.01 g), and the device must capture energy from the movement in any direction. According to our experiments, the device is capable to generate average powers around the milliwatt in the operation conditions of a wind turbine, which are enough for some very-low power sensor nodes, or at least to considerably extend the life-time of batteries. The device is based on the principle of moving (inertial) masses comprised of magnets in Hallbach arrays interacting with coils, and can work for movements on any direction of a plane. To the best of our knowledge, this is the first device specifically proposed for wind turbines and one of the few that work in such low frequencies, and capture energy from movements on any direction on a plane. Only three harvesters proposed in the literature, intended for distinct applications, can work at such low frequencies, and our device exhibits a better efficiency. Though comparisons with harvesters working in different contexts and, even using different conversion principles, is not completely fair, we make in this paper a comparison to the closest ones, resorting to two different figures of merit.
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    PublicationOpen Access
    Design of MOS-translinear multiplier/dividers in analog VLSI
    (Hindawi Publishing Corporation, 2000) López Martín, Antonio; Carlosena García, Alfonso; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    A general framework for designing current-mode CMOS analog multiplier/divider circuits based on the cascade connection of a geometric-mean circuit and a squarer/ divider is presented. It is shown how both building blocks can be readily obtained from a generic second-order MOS translinear loop. Various implementations are proposed, featuring simplicity, favorable precision and wide dynamic range. They can be successfully employed in a wide range of analog VLSI processing tasks. Experimental results of two versions, based on stacked and folded MOS-translinear loops and fabricated in a 2.4-1am CMOS process, are provided in order to verify the correctness of the proposed approach.
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    PublicationOpen Access
    Comprehensive characterisation of a low-frequency-vibration energy harvester
    (MDPI, 2024) Plaza Puértolas, Aitor; Iriarte Goñi, Xabier; Castellano Aldave, Jesús Carlos; Carlosena García, Alfonso; Ingeniería; Ingeniaritza; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
    In this paper, we describe a measurement procedure to fully characterise a novel vibration energy harvester operating in the ultra-low-frequency range. The procedure, which is more thorough than those usually found in the literature, comprises three main stages: modelling, experimental characterisation and parameter identification. Modelling is accomplished in two alternative ways, a physical model (white box) and a mixed one (black box), which model the magnetic interaction via Fourier series. The experimental measurements include not only the input (acceleration)–output (energy) response but also the (internal) dynamic behaviour of the system, making use of a synchronised image processing and signal acquisition system. The identification procedure, based on maximum likelihood, estimates all the relevant parameters to characterise the system to simulate its behaviour and helps to optimise its performance. While the method is custom-designed for a particular harvester, the comprehensive approach and most of its procedures can be applied to similar harvesters.
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    PublicationOpen Access
    Glottal spectrum based inverse filtering
    (ISCA, 2003) Arroabarren Alemán, Ixone; Carlosena García, Alfonso; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    In this paper a new inverse filtering technique for the time-domain estimation of the glottal excitation is presented. This approach uses the DAP modeling for the vocal tract characterization, and a spectral model for the derivative of the glottal flow. This spectral model is based on the spectrum of the KLGLOTT88 model for the glottal source. The proposed procedure removes the glottal source from the spectrum of the speech signal in an accurate manner, particularly for highpitched signals and singing voice, and the estimated glottal waveforms present less amount of formant ripple.