A Decision Tree and S-Transform Based Approach for Power Quality Disturbances Classification

In this paper, it is presented an automated classification based on S-transform as feature extraction tool and Decision Tree as algorithm classifier. The signals generated according to mathematical models, including complex disturbances, have been used to design and test this approach, where noise is added to the signals from 40dB to 20dB. Finally, several disturbances, simple and complex, have been considered to test the implemented system. Evaluation results verifying the accuracy of the proposed method are presented.IEE

An investigation into the perspectives of providers and learners on MOOC accessibility

An effective open eLearning environment should consider the target learner’s abilities, learning goals, where learning takes place, and which specific device(s) the learner uses. MOOC platforms struggle to take these factors into account and typically are not accessible, inhibiting access to environments that are intended to be open to all. A series of research initiatives are described that are intended to benefit MOOC providers in achieving greater accessibility and disabled learners to improve their lifelong learning and re-skilling. In this paper, we first outline the rationale, the research questions, and the methodology. The research approach includes interviews, online surveys and a MOOC accessibility audit; we also include factors such the risk management of the research programme and ethical considerations when conducting research with vulnerable learners. Preliminary results are presented from interviews with providers and experts and from analysis of surveys of learners. Finally, we outline the future research opportunities. This paper is framed within the context of the Doctoral Consortium organised at the TEEM'17 conference

A critical comparison between DWT and Hilbert-Huang-based methods for the diagnosis of rotor bar failures in induction machines

(c) 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] In this paper, a cutting-edge time-frequency decomposition tool, i.e., the Hilbert-Huang transform (HHT), is applied to the stator startup current to diagnose the presence of rotor asymmetries in induction machines. The objective is to extract the evolution during the startup transient of the left sideband harmonic (LSH) caused by the asymmetry, which constitutes a reliable evidence of the presence of the fault. The validity of the diagnosis methodology is assessed through several tests developed using real experimental signals. Moreover, in this paper, an analytical comparison with an alternative time-frequency decomposition tool, i.e., the discrete wavelet transform (DWT), is carried out. This tool was applied in previous works to the transient extraction of fault-related components, with satisfactory results, even in cases in which the classical Fourier approach does not lead to correct results. The results of the application of the HHT and DWT are analyzed and compared, obtaining novel conclusions about their respective suitability for the transient extraction of asymmetry-related components, as well as the equivalence, with regard to the LSH extraction, between their basic components, namely: 1) intrinsic mode function, for the HHT, and 2) approximation signal for the DWT.This work was supported in part by the Spanish “Ministerio de Educación y Ciencia,” in the framework of the “Programa Nacional de proyectos de Investigación Fundamental,” project reference DPI2008-06583/DPI and in part by “Vicerrectorado de Investigación, Desarrollo e Innovación of the Universidad Politécnica de Valencia” through the Programa de Apoyo a la Investigación y Desarrollo under Contract PAID-06-07.Antonino-Daviu, J.; Riera-Guasp, M.; Pineda-Sanchez, M.; Pérez, RB. (2009). A critical comparison between DWT and Hilbert-Huang-based methods for the diagnosis of rotor bar failures in induction machines. IEEE Transactions on Industry Applications. 45(5):1794-1803. https://doi.org/10.1109/TIA.2009.2027558S1794180345

De los centros TIC al PRODIG: evolución de los planes de formación del profesorado

En el presente trabajo abordaremos parte de los resultados de una investigación en la que hemos analizado la evolución de los planes de formación de la Consejería de Educación de la Junta de Andalucía para favorecer la implementación de los distintos planes de introducción de las TIC en las aula desde la puesta en marcha de los llamados “centros TIC” hasta el Programa de Digitalización de Centro (PRODIG) iniciado en este curso 2018-2019. Desde que la Junta de Andalucía aprobó el Decreto 72/2003 de Medidas de Impulso de la Sociedad del Conocimiento, la apuesta de la administración por la formación del profesorado de enseñanzas obligatorias fue muy ambiciosa. En general el impacto en los centros por el proyecto TIC fue muy positivo en opinión de la mayoría de los docentes, destacando principalmente el aumento en la motivación del alumnado. A pesar de ello, la formación ofrecida por parte de la administración era una de las mejoras que se demandaban. El siguiente plan de introducción de tecnología en las aula fue el proyecto “Escuela TIC 2.0”, que dotó a los centros de aulas con pizarras digitales y conexión Wifi, así como de dispositivos portátiles para el alumnado. En este caso, el profesorado manifestó igualmente la necesidad de una formación más centrada en los pedagógico que en lo tecnológico y que diera prioridad a fomentar los cambios metodológicos que se demandaban en los procesos de enseñanza-aprendizaje. La última apuesta (PRODIG) se ha iniciado este curso 2018-2019 con el fin de fomentar el cambio metodológico en los centros educativos, partiendo de la base expuesta en diferentes estudios previos realizados que afirman que la mera dotación tecnológica de los centros docentes no implica cambios en los procesos de enseñanza-aprendizaje si no se sustenta en cambios pedagógicos profundos que surjan de las necesidades de cada uno de los centros educativos.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Influence of the electric field on the latent heat of the ferroelectric phase transition in KDP

The specific heat, heat flux (DTA trace) and dielectric constant of KDP ferroelectric crystal have been measured simultaneously for various electric fields with a conduction calorimeter. The specific heat presents a strong anomaly but these simultaneous measurements allow us to evaluate the latent heat accurately. Latent heat decreases with field and the value of critical electric field --that where latent heat disappears-- is estimated to be (0.44\pm0.03) kV/cm. Incidentally, we have measured simultaneously the dielectric permittivity which suggests that latent heat is developed as domains are growing.Comment: 7 pages, 6 figures, ReVTeX, twocolumn format, to appear in J. Phys. Cond. Matte

Influence of non-Consecutive Bar Breakages in Motor Current Signature Analysis for the Diagnosis of Rotor Faults in Induction Motors

(c) 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] Studies of rotor asymmetries in squirrel-cage induction motors have traditionally focused on analyses of the effects of the breakage of adjacent bars on the magnetic field and current spectrum. However, major motor manufacturers have reported cases where damaged bars are randomly distributed around the rotor perimeter of large HV machines. In some of these cases, the motors were being monitored under maintenance programs based on motor current signature analysis (MCSA), and the degree of degradation found in the rotor was much greater than that predicted by analysis of their current spectra. For this reason, a complete study was carried out, comprising a theoretical analysis, as well as simulation and tests, to investigate the influence that the number and location of faulty bars has on the traditional MCSA diagnosis procedure. From the theoretical analysis, based on the application of the fault-current approach and space-vector theory, a very simple method is deduced, which enables the left sideband amplitude to be calculated for any double bar breakage, per unit of the sideband amplitude corresponding to a single breakage. The proposed methodology is generalized for the estimation of the sideband amplitude in the case of multiple bar breakages and validated by simulation using a finite-element-based model, as well as by laboratory tests.This work was supported by the Spanish Ministerio de Educacion y Ciencia under ´ the framework of the Programa Nacional de proyectos de Investigacion Funda- ´mental Project Reference DPI2008-06583/DPI. Paper no. TEC-00393-2008Riera-Guasp, M.; Fernandez Cabanas, M.; Antonino-Daviu, J.; Pineda-Sanchez, M.; Rojas García, CH. (2010). Influence of non-Consecutive Bar Breakages in Motor Current Signature Analysis for the Diagnosis of Rotor Faults in Induction Motors. IEEE Transactions on Energy Conversion. 25(1):80-89. https://doi.org/10.1109/TEC.2009.2032622S808925

Optimal Power Dispatch in a Microgrid

This paper is concerned with the power dispatch in a microgrid. The dispatch problem is formulated as linear program. Thus, the proposed solution is the application of neural network that solves linear programming on-line. This proposal in motivated by the increasing electric energy demand and the rising need to incorporate sustainable energy sources to the power grid in a reliable scheme. A microgrid is an interconnection of distributed energy sources (DES), with the tendency to include renewable energies that offer many advantages to customers and utilities. The different DES that compose the microgrid are controlled independently to track the optimal reference provided by the proposed method in order to supply a demanded power output minimizing the consumed power from the main grid.ITESO, A.C.CINVESTAV-IP

Versatile Graphene-Based Platform for Robust Nanobiohybrid Interfaces

Technologically useful and robust graphene-based interfaces for devices require the introduction of highly selective, stable, and covalently bonded functionalities on the graphene surface, whilst essentially retaining the electronic properties of the pristine layer. This work demonstrates that highly controlled, ultrahigh vacuum covalent chemical functionalization of graphene sheets with a thiol-terminated molecule provides a robust and tunable platform for the development of hybrid nanostructures in different environments. We employ this facile strategy to covalently couple two representative systems of broad interest: metal nanoparticles, via S-metal bonds, and thiol-modified DNA aptamers, via disulfide bridges. Both systems, which have been characterized by a multi-technique approach, remain firmly anchored to the graphene surface even after several washing cycles. Atomic force microscopy images demonstrate that the conjugated aptamer retains the functionality required to recognize a target protein. This methodology opens a new route to the integration of high-quality graphene layers into diverse technological platforms, including plasmonics, optoelectronics, or biosensing. With respect to the latter, the viability of a thiol-functionalized chemical vapor deposition graphene-based solution-gated field-effect transistor array was assessed

Diagnosis of Induction Motor Faults in Time-Varying Conditions Using the Polynomial-Phase Transform of the Current

© 2011 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] Transient motor current signature analysis is a recently developed technique for motor diagnostics using speed transients. The whole speed range is used to create a unique stamp of each fault harmonic in the time-frequency plane. This greatly increases diagnostic reliability when compared with non-transient analysis, which is based on the detection of fault harmonics at a single speed. But this added functionality comes at a price: well-established signal analysis tools used in the permanent regime, mainly the Fourier transform, cannot be applied to the nonstationary currents of a speed transient. In this paper, a new method is proposed to fill this gap. By applying a polynomial-phase transform to the transient current, a new, stationary signal is generated. This signal contains information regarding the fault components along the different regimes covered by the transient, and can be analyzed using the Fourier transform. The polynomial-phase transform is used in radar, sonar, communications, and power systems fields, but this is the first time, to the best knowledge of the authors, that it has been applied to the diagnosis of induction motor faults. Experimental results obtained with two different commercial motors with broken bars are presented to validate the proposed method.This work was supported by the Spanish "Ministerio de Educacion y Ciencia" in the framework of the "Programa Nacional de Proyectos de Investigacion Fundamental," project reference DPI2008-06583/DPI.Pineda-Sanchez, M.; Riera-Guasp, M.; Roger-Folch, J.; Antonino-Daviu, J.; Pérez-Cruz, J.; Puche-Panadero, R. (2011). Diagnosis of Induction Motor Faults in Time-Varying Conditions Using the Polynomial-Phase Transform of the Current. IEEE Transactions on Industrial Electronics. 58(4):1428-1439. https://doi.org/10.1109/TIE.2010.2050755S1428143958

Diagnosis of induction motor faults via gabor analysis of the current in transient regime

© 2011 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] Time-frequency analysis of the transient current in induction motors (IMs) is the basis of the transient motor current signature analysis diagnosis method. IM faults can be accurately identified by detecting the characteristic pattern that each type of fault produces in the time-frequency plane during a speed transient. Diverse transforms have been proposed to generate a 2-D time-frequency representation of the current, such as the short time Fourier transform (FT), the wavelet transform, or the Wigner-Ville distribution. However, a fine tuning of their parameters is needed in order to obtain a high-resolution image of the fault in the time-frequency domain, and they also require a much higher processing effort than traditional diagnosis techniques, such as the FT. The new method proposed in this paper addresses both problems using the Gabor analysis of the current via the chirp z-transform, which can be easily adapted to generate high-resolution time-frequency stamps of different types of faults. In this paper, it is used to diagnose broken bars and mixed eccentricity faults of an IM using the current during a startup transient. This new approach is theoretically introduced and experimentally validated with a 1.1-kW commercial motor in faulty and healthy conditions. © 2012 IEEE.This work was supported by the Spanish Ministerio de Ciencia e Innovacion (MICINN) in the framework of the VI Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica 2008-2011. (Programa Nacional de proyectos de Investigacion Fundamental, project reference DPI2011-23740). The Associate Editor coordinating the review process for this paper was Dr. Subhas Mukhopadhyay.Riera-Guasp, M.; Pineda-Sanchez, M.; Pérez-Cruz, J.; Puche-Panadero, R.; Roger-Folch, J.; Antonino-Daviu, J. (2012). Diagnosis of induction motor faults via gabor analysis of the current in transient regime. IEEE Transactions on Instrumentation and Measurement. 61(6):1583-1596. doi:10.1109/TIM.2012.2186650S1583159661