EEG-based biometrics: Effects of template ageing

This chapter discusses the effects of template ageing in EEG-based biometrics. The chapter also serves as an introduction to general biometrics and its main tasks: Identification and verification. To do so, we investigate different characterisations of EEG signals and examine the difference of performance in subject identification between single session and cross-session identification experiments. In order to do this, EEG signals are characterised with common state-of-the-art features, i.e. Mel Frequency Cepstral Coefficients (MFCC), Autoregression Coefficients, and Power Spectral Density-derived features. The samples were later classified using various classifiers, including Support Vector Machines and k-Nearest Neighbours with different parametrisations. Results show that performance tends to be worse for crosssession identification compared to single session identification. This finding suggests that temporal permanence of EEG signals is limited and thus more sophisticated methods are needed in order to characterise EEG signals for the task of subject identificatio

BED: A new dataset for EEG-based biometrics

Various recent research works have focused on the use of electroencephalography (EEG) signals in the field of biometrics. However, advances in this area have somehow been limited by the absence of a common testbed that would make it possible to easily compare the performance of different proposals. In this work, we present a dataset that has been specifically designed to allow researchers to attempt new biometric approaches that use EEG signals captured by using relatively inexpensive consumer-grade devices. The proposed dataset has been made publicly accessible and can be downloaded from https://doi.org/10.5281/zenodo.4309471. It contains EEG recordings and responses from 21 individuals, captured under 12 different stimuli across three sessions. The selected stimuli included traditional approaches, as well as stimuli that aim to elicit concrete affective states, in order to facilitate future studies related to the influence of emotions on the EEG signals in the context of biometrics. The captured data were checked for consistency and a performance study was also carried out in order to establish a baseline for the tasks of subject verification and identification

TCO-free low-temperature p+ emitters for back-junction c-Si solar cells

In this work, we report on the fabrication and characterization of n-type c-Si solar cells whose p+ emitters are based on laser processed aluminum oxide/silicon carbide (Al2O3/SiCx) films. The p+ emitter is defined at the rear side of the cell and it consists of point-like laser-diffused p+ regions with a surface charge induced emitter in between based on the high negative charge located at the Al2O3/c-Si interface. These emitters are fabricated at low temperature (1000 nm) that reach the rear surface of the cell resulting in an excellent back reflector. We fabricated solar cells with distance between p+ regions or pitch ranging from 200 to 350 µm with a front surface based on silicon heterojunction technology. Best efficiency (18.1%) is obtained for a pitch of 250 µm as a consequence of the trade-off between Voc and FF values.Peer ReviewedPostprint (published version

Experimental validation of a quasi-two-dimensional radial turbine model

[EN] This article presents the experimental validation of a quasi-two-dimensional radial turbine model able to be used in turbocharged reciprocating internal combustion engine simulations. A passenger car variable-geometry turbine has been tested under steady and pulsating flow conditions, instrumented with multiple pressure probes, temperature sensors and mass flow sensors. Using the data obtained, a pressure decomposition has been performed. The pressure at the turbine inlet and outlet has been split into forward and backward travelling waves, employing the reflected and transmitted waves to verify the goodness of the model. The experimental results have been used to compare the quasi-two-dimensional radial turbine model as well as a classic one-dimensional model. The quasi-two-dimensional code presents a good degree of correlation with the experimental results, providing better results than the one-dimensional approach, especially when studying the high-frequency spectrum.Pablo Soler is partially supported through contract FPI-2017-S2-1428 of Programa de Apoyo para la Investigación y Desarrollo (PAID) of Universitat Politècnica de València. The authors of this paper wish to thank M.A. Ortiz and V. Ucedo for their invaluable work during the experimental setup and the campaign.Galindo, J.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Soler-Blanco, P. (2018). Experimental validation of a quasi-two-dimensional radial turbine model. International Journal of Engine Research. https://doi.org/10.1177/1468087418788502SKesgin, U. (2005). Effect of turbocharging system on the performance of a natural gas engine. Energy Conversion and Management, 46(1), 11-32. doi:10.1016/j.enconman.2004.02.006Tang, H., Pennycott, A., Akehurst, S., & Brace, C. J. (2014). A review of the application of variable geometry turbines to the downsized gasoline engine. International Journal of Engine Research, 16(6), 810-825. doi:10.1177/1468087414552289Pesiridis, A. (2012). The application of active control for turbocharger turbines. International Journal of Engine Research, 13(4), 385-398. doi:10.1177/1468087411435205Romagnoli, A., & Martinez-Botas, R. (2011). Performance prediction of a nozzled and nozzleless mixed-flow turbine in steady conditions. International Journal of Mechanical Sciences, 53(8), 557-574. doi:10.1016/j.ijmecsci.2011.05.003Payri, F., Serrano, J. R., Fajardo, P., Reyes-Belmonte, M. A., & Gozalbo-Belles, R. (2012). A physically based methodology to extrapolate performance maps of radial turbines. Energy Conversion and Management, 55, 149-163. doi:10.1016/j.enconman.2011.11.003Costall, A. W., McDavid, R. M., Martinez-Botas, R. F., & Baines, N. C. (2010). Pulse Performance Modeling of a Twin Entry Turbocharger Turbine Under Full and Unequal Admission. Journal of Turbomachinery, 133(2). doi:10.1115/1.4000566De Bellis, V., & Marelli, S. (2015). One-dimensional simulations and experimental analysis of a wastegated turbine for automotive engines under unsteady flow conditions. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 229(13), 1801-1816. doi:10.1177/0954407015571672Serrano, J. R., Olmeda, P., Páez, A., & Vidal, F. (2010). An experimental procedure to determine heat transfer properties of turbochargers. Measurement Science and Technology, 21(3), 035109. doi:10.1088/0957-0233/21/3/035109Burke, R. D., Copeland, C. D., Duda, T., & Rayes-Belmote, M. A. (2016). Lumped Capacitance and Three-Dimensional Computational Fluid Dynamics Conjugate Heat Transfer Modeling of an Automotive Turbocharger. Journal of Engineering for Gas Turbines and Power, 138(9). doi:10.1115/1.4032663Olmeda, P., Dolz, V., Arnau, F. J., & Reyes-Belmonte, M. A. (2013). Determination of heat flows inside turbochargers by means of a one dimensional lumped model. Mathematical and Computer Modelling, 57(7-8), 1847-1852. doi:10.1016/j.mcm.2011.11.078Serrano, J., Olmeda, P., Arnau, F., Reyes-Belmonte, M., & Lefebvre, A. (2013). Importance of Heat Transfer Phenomena in Small Turbochargers for Passenger Car Applications. SAE International Journal of Engines, 6(2), 716-728. doi:10.4271/2013-01-0576Aghaali, H., Ångström, H.-E., & Serrano, J. R. (2014). Evaluation of different heat transfer conditions on an automotive turbocharger. International Journal of Engine Research, 16(2), 137-151. doi:10.1177/1468087414524755Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Theoretical and experimental study of mechanical losses in automotive turbochargers. Energy, 55, 888-898. doi:10.1016/j.energy.2013.04.042Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Importance of Mechanical Losses Modeling in the Performance Prediction of Radial Turbochargers under Pulsating Flow Conditions. SAE International Journal of Engines, 6(2), 729-738. doi:10.4271/2013-01-0577Galindo, J., Fajardo, P., Navarro, R., & García-Cuevas, L. M. (2013). Characterization of a radial turbocharger turbine in pulsating flow by means of CFD and its application to engine modeling. Applied Energy, 103, 116-127. doi:10.1016/j.apenergy.2012.09.013Hakeem, I., Su, C.-C., Costall, A., & Martinez-Botas, R. F. (2007). Effect of volute geometry on the steady and unsteady performance of mixed-flow turbines. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 221(4), 535-549. doi:10.1243/09576509jpe314Hu X. An advanced turbocharger model for the internal combustion engine. PhD Thesis, Purdue University, West Lafayette, IN, 2000.King A. A turbocharger unsteady performance model for the GT-power internal combustion engine simulation. PhD Thesis, Purdue University, West Lafayette, IN, 2000.Rajoo, S., & Martinez-Botas, R. (2008). Variable Geometry Mixed Flow Turbine for Turbochargers: An Experimental Study. International Journal of Fluid Machinery and Systems, 1(1), 155-168. doi:10.5293/ijfms.2008.1.1.155Serrano, J. R., Tiseira, A., García-Cuevas, L. M., Inhestern, L. B., & Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design conditions. Energy, 125, 72-84. doi:10.1016/j.energy.2017.02.118Torregrosa, A. J., Broatch, A., Navarro, R., & García-Tíscar, J. (2014). Acoustic characterization of automotive turbocompressors. International Journal of Engine Research, 16(1), 31-37. doi:10.1177/1468087414562866Leufvén, O., & Eriksson, L. (2014). Measurement, analysis and modeling of centrifugal compressor flow for low pressure ratios. International Journal of Engine Research, 17(2), 153-168. doi:10.1177/1468087414562456Galindo, J., Tiseira, A., Navarro, R., Tarí, D., & Meano, C. M. (2017). Effect of the inlet geometry on performance, surge margin and noise emission of an automotive turbocharger compressor. Applied Thermal Engineering, 110, 875-882. doi:10.1016/j.applthermaleng.2016.08.099Galindo, J., Tiseira, A., Fajardo, P., & García-Cuevas, L. M. (2014). Development and validation of a radial variable geometry turbine model for transient pulsating flow applications. Energy Conversion and Management, 85, 190-203. doi:10.1016/j.enconman.2014.05.072Ding, Z., Zhuge, W., Zhang, Y., Chen, H., Martinez-Botas, R., & Yang, M. (2017). A one-dimensional unsteady performance model for turbocharger turbines. Energy, 132, 341-355. doi:10.1016/j.energy.2017.04.154Toro, E. F., Spruce, M., & Speares, W. (1994). Restoration of the contact surface in the HLL-Riemann solver. Shock Waves, 4(1), 25-34. doi:10.1007/bf01414629Van Leer, B. (1974). Towards the ultimate conservative difference scheme. II. Monotonicity and conservation combined in a second-order scheme. Journal of Computational Physics, 14(4), 361-370. doi:10.1016/0021-9991(74)90019-9Courant, R., Friedrichs, K., & Lewy, H. (1928). �ber die partiellen Differenzengleichungen der mathematischen Physik. Mathematische Annalen, 100(1), 32-74. doi:10.1007/bf01448839Chiong, M. S., Rajoo, S., Romagnoli, A., Costall, A. W., & Martinez-Botas, R. F. (2015). Non-adiabatic pressure loss boundary condition for modelling turbocharger turbine pulsating flow. Energy Conversion and Management, 93, 267-281. doi:10.1016/j.enconman.2014.12.058Serrano, J. R., Arnau, F. J., García-Cuevas, L. M., Dombrovsky, A., & Tartoussi, H. (2016). Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions. Energy Conversion and Management, 128, 281-293. doi:10.1016/j.enconman.2016.09.032Serrano, J. R., Arnau, F. J., Dolz, V., Tiseira, A., & Cervelló, C. (2008). A model of turbocharger radial turbines appropriate to be used in zero- and one-dimensional gas dynamics codes for internal combustion engines modelling. Energy Conversion and Management, 49(12), 3729-3745. doi:10.1016/j.enconman.2008.06.031Piñero, G., Vergara, L., Desantes, J. M., & Broatch, A. (2000). Estimation of velocity fluctuation in internal combustion engine exhaust systems through beamforming techniques. Measurement Science and Technology, 11(11), 1585-1595. doi:10.1088/0957-0233/11/11/307Harris, F. J. (1978). On the use of windows for harmonic analysis with the discrete Fourier transform. Proceedings of the IEEE, 66(1), 51-83. doi:10.1109/proc.1978.1083

Importance of Heat Transfer Phenomena in Small Turbochargers for Passenger Car Applications

[EN] Nowadays turbocharging the internal combustion engine has become a key point in the reduction on pollutant emissions and the improvement on engine performance. The matching between the turbocharger and the engine is vital due to the highly unsteady flow the turbocharger works with. In the present paper the importance of the heat transfer phenomena inside small automotive turbochargers will be analyzed. This phenomenon will be studied from the point of view of both the turbine and the compressor in one-dimensional modelling. The goodness of the model will be demonstrated predicting turbine and compressor outlet temperatures. An accurate prediction of these parameters will be key designing the intercooler and the after treatment devices. A series of tests in a gas stand with steady and pulsating hot flow in the turbine side will be modeled to show the good agreement in turbocharger enthalpies prediction.This paper is partially supported by the Universitat Politècnica de València PAID-06-11 2034.Serrano Cruz, JR.; Olmeda González, PC.; Arnau Martínez, FJ.; Reyes Belmonte, MA.; Lefebvre, A. (2013). Importance of Heat Transfer Phenomena in Small Turbochargers for Passenger Car Applications. SAE International Journal of Engines. 6(2):1-13. doi:10.4271/2013-01-0576S1136

Use of New Methodologies for Students Assessment in Large Groups in Engineering Education

[EN] In this paper, a student evaluation methodology which applies the concept of continuous assessment proposed by Bologna is presented for new degrees in higher education. An important part of the student's final grade is based on the performance of several individual works throughout the semester. The paper shows the correction system used which is based on using a spreadsheet with macros and a template in which the student provides the solution of each task. The employ of this correction system together with the available e-learning platform allows the teachers to perform automatic tasks evaluations compatible with courses with large number of students. The paper also raises the different solutions adopted to avoid plagiarism and to try that the final grade reflects, as closely as possible, the knowledge acquired by the students.Tormos Martínez, BV.; Climent, H.; Olmeda González, PC.; Arnau Martínez, FJ. (2014). Use of New Methodologies for Students Assessment in Large Groups in Engineering Education. Multidisciplinary Journal for Education, Social and Technological Sciences. 1(1):121-152. doi:10.4995/muse.2014.2198SWORD1211521

Genealogies. Rescatar penyores

[ca] Com a «penyores»... coneixem aquells objectes que es deixen en poder d’algú, com a prova de retorn o com a promesa de record. Penyores són també aquells estris oblidats en espais en desús, peces descartades, de manera conscient o involuntària —descuidar-se, fugir. Els espais que ens envolten, on diàriament vivim i treballem, acumulen artefactes carregats de vivències, històries i faules de qui abans els ha emprat. Narren èxits, fracassos, formes de viure; si més no, la màgia de la quotidianitat. Independentment de l’estadi vital on s’estigui —joventut o senectut—, s’entén la importància i el potencial de reutilitzar el que s’ha llegat: per acostar-se a la memòria, rellegir-la, fer-ne crida, furgar-hi, reivindicar i, siguin els que siguin, propiciar canvis a situacions actuals. A «Genealogies. Rescatar penyores», artistes novells, artistes convidats i professorat de la Facultat de Belles Arts de la Universitat de Barcelona, amb la complicitat del públic assistent, miren d’aportar noves visions sobre els objectes i els temps pignorats que contenen, com a punt de partida per encetar un diàleg narratiu de tint feminista, econòmic, de cura, de sostenibilitat emocional

Jardins per a la salut

Facultat de Farmàcia, Universitat de Barcelona. Ensenyament: Grau de Farmàcia. Assignatura: Botànica farmacèutica. Curs: 2014-2015. Coordinadors: Joan Simon, Cèsar Blanché i Maria Bosch.Els materials que aquí es presenten són el recull de les fitxes botàniques de 128 espècies presents en el Jardí Ferran Soldevila de l’Edifici Històric de la UB. Els treballs han estat realitzats manera individual per part dels estudiants dels grups M-3 i T-1 de l’assignatura Botànica Farmacèutica durant els mesos de febrer a maig del curs 2014-15 com a resultat final del Projecte d’Innovació Docent «Jardins per a la salut: aprenentatge servei a Botànica farmacèutica» (codi 2014PID-UB/054). Tots els treballs s’han dut a terme a través de la plataforma de GoogleDocs i han estat tutoritzats pels professors de l’assignatura. L’objectiu principal de l’activitat ha estat fomentar l’aprenentatge autònom i col·laboratiu en Botànica farmacèutica. També s’ha pretès motivar els estudiants a través del retorn de part del seu esforç a la societat a través d’una experiència d’Aprenentatge-Servei, deixant disponible finalment el treball dels estudiants per a poder ser consultable a través d’una Web pública amb la possibilitat de poder-ho fer in-situ en el propi jardí mitjançant codis QR amb un smartphone