Innovación en la recogida de datos para una investigación de carácter cualitativo. Un ejemplo con alumnos universitarios en un entorno computacional

La introducción de una herramienta software que captura la pantalla del ordenador en el proceso de recogida de datos, nos aporta un tipo de información que nos permite conocer algunos aspectos de la utilización que hacen los estudiantes de una herramienta de cálculo simbólico como Maple y nos facilita el proceso de análisis al respaldar la triangulación de los datos obtenidos mediante grabaciones de video

Acoustic biometric system based on preprocessing techniques and linear support vector machines

Producción CientíficaDrawing on the results of an acoustic biometric system based on a MSE classifier, a new biometric system has been implemented. This new system preprocesses acoustic images, extracts several parameters and finally classifies them, based on Support Vector Machine (SVM). The preprocessing techniques used are spatial filtering, segmentation—based on a Gaussian Mixture Model (GMM) to separate the person from the background, masking—to reduce the dimensions of images—and binarization—to reduce the size of each image. An analysis of classification error and a study of the sensitivity of the error versus the computational burden of each implemented algorithm are presented. This allows the selection of the most relevant algorithms, according to the benefits required by the system. A significant improvement of the biometric system has been achieved by reducing the classification error, the computational burden and the storage requirements

Virtual Laboratory Methodologies in Electrical Engineering

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Optimization of a Biometric System Based on Acoustic Images

On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced

Study of the Multipactor Effect in Groove Gap Waveguide Technology

This paper presents a theoretical and experimental comparative study of the different multipactor threshold values obtained in rectangular waveguide (RW) and groove gap waveguide (GGW). To this end, the multipactor effect has been first analysed in a RW with a recently developed theoretical model. Then, the multipactor breakdown power levels in the equivalent GGW have been predicted with an accurate electron tracking code, showing a significant increment compared with the RW case. In order to validate these results, two E-plane WR-90 rectangular waveguide transformers have been designed with a full-wave electromagnetic simulation tool. The central sections of these transformers have been implemented in RW and GGW, respectively, and their multipactor breakdown power levels have also been predicted. The two designed transformers have been fabricated in aluminium, and then measured in terms of electrical response (scattering parameters) and RF multipactor effect (power threshold values). All the experimental results agree well with the set of simulated data, thus fully validating the performed study

Study of the Multipactor Effect in Groove Gap Waveguide Technology

[EN] This article presents a theoretical and experimental comparative study of the different multipactor threshold values obtained in the rectangular waveguide (RW) and the groove gap waveguide (GGW). To this end, the multipactor effect has been first analyzed in an RW with a recently developed theoretical model. Then, the multipactor breakdown power levels in the equivalent GGW have been predicted with an accurate electron tracking code, showing a significant increment compared with the RW case. In order to validate these results, two E-plane WR-90 RW transformers have been designed with a full-wave electromagnetic simulation tool. The central sections of these transformers have been implemented in RW and GGW, respectively, and their multipactor breakdown power levels have also been predicted. The two designed transformers have been fabricated in aluminum and then measured in terms of electrical response (scattering parameters) and RF multipactor effect (power threshold values). All the experimental results agree well with the set of simulated data, thus fully validating the performed study.This work was supported by the Ministerio de Ciencia e Innovacion, Spanish Government, through the Subprojects C41 and C43 of the Coordinated Research and Development Project PID2019103982RB under Grant MCIN/AEI/10.13039/501100011033.Vague Cardona, JJ.; Asensio, I.; Coves, Á.; San Blas, ÁA.; Reglero Mangada, MS.; Vidal Pantaleoni, A.; Raboso, D.... (2022). Study of the Multipactor Effect in Groove Gap Waveguide Technology. IEEE Transactions on Microwave Theory and Techniques. 70(5):2566-2578. https://doi.org/10.1109/TMTT.2022.31575872566257870