Search results for "Enginyeria elèctrica"
showing 10 items of 13 documents
Novel Wood Resistance Measurement Method Reducing the Initial Transient Instabilities Arising in DC Methods Due to Polarization Effects
2019
A novel method for measuring the electrical resistance in wood is presented. It is based on applying an Alternating Current (AC) to two electrodes rammed into the wood. The method reduces the transient time for value stabilization. In case of Direct Current (DC) resistance measurement methods, typically used in wood measurement, an initial transient exists, invalidating the measured value during an initial transient period. This measurement method uses an electronic circuit based on a relaxation oscillator where the wood automatically sets the oscillation frequency depending on its electrical resistance. Compared to other AC methods, this circuit greatly simplifies the measurement process, …
Lightning-ignited wildfires and long continuing current lightning in the Mediterranean Basin: Preferential meteorological conditions
2021
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Moving Learning Machine Towards Fast Real-Time Applications: A High-Speed FPGA-based Implementation of the OS-ELM Training Algorithm
2018
Currently, there are some emerging online learning applications handling data streams in real-time. The On-line Sequential Extreme Learning Machine (OS-ELM) has been successfully used in real-time condition prediction applications because of its good generalization performance at an extreme learning speed, but the number of trainings by a second (training frequency) achieved in these continuous learning applications has to be further reduced. This paper proposes a performance-optimized implementation of the OS-ELM training algorithm when it is applied to real-time applications. In this case, the natural way of feeding the training of the neural network is one-by-one, i.e., training the neur…
Zero Ripple Current with Coupled Inductors in Continuous Conduction Mode under PWM Signals
2020
This article presents a generalized analysis to explain current ripple of an $m$ windings coupled inductor with a given coupling factor $k_{ij}$ for each pair of windings and then studies more in detail its use in the continuous conduction mode and with pulsewidth modulated signals. To determine the current ripple, a generalized expression of the equivalent inductance of each winding is calculated, including the influence of voltage unbalance. In the ideal case, the equivalent inductance shows that the current ripple can only become $m$ times smaller than that with uncoupled inductors. But in the unbalanced case, some divergences of the equivalent inductance appear that are responsible for …
Use of acousto-Optic Filters in imaging applications. A contribution to the SmartSpectra project
2009
This Thesis analyses the use of an acousto-optic tunable filter (AOTF) for the realisation of spectral imaging systems. An AOTF is an electronically tunable spectral bandpass optical filter. It consists on a crystal that, excited with acoustic waves, diffracts and then separates a single wavelength of light from a broadband source. The wavelength of selected light is a function of the frequency of the signal applied to the crystal. We have implemented a spectral imaging instrument called Autonomous Tunable Filtering System (ATFS) that includes an AOTF in order to acquire multispectral images with a monochrome digital camera. Careful design and calibration permits its use in spectroscopic ap…
Detección automática de podredumbres en cítricos mediante procesado avanzado de imágenes hiperespectrales
2010
La citricultura constituye actualmente una parte importantísima de la economía en la Comunidad Valenciana. Uno de los principales problemas presentes en la industria citrícola son las podredumbres producidas por los hongos Penicillium digitatum y Penicillium italicum. La detección temprana del daño producido por los hongos en los cítricos es especialmente importante para la industria distribuidora de cítricos, ya que un reducido número de frutas infectadas puede diseminar la infección a toda una partida de cítricos, produciendo grandes pérdidas económicas. Actualmente en la industria citrícola la inspección y eliminación de cítricos dañados por podredumbres se realiza de manera manual por o…
A Simultaneous Observation of Lightning by ASIM, Colombia-Lightning Mapping Array, GLM, and ISS-LIS
2021
The Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS) provides optical radiances and images of lightning flashes in several spectral bands. This work presents a lightning flash simultaneously observed from space by ASIM, the Geostationary Lightning Mapper (GLM) and the Lightning Imaging Sensor on the International Space Station (ISS-LIS); and from ground by the Colombia-Lightning Mapping Array (Colombia-LMA). Volumetric weather radar provides reflectivity data to help to interpret the effects of the cloud particles on the observed optical features. We found that surges in radiance in the band at 777.4 nm appear to be related mostly with lightning processe…
Machine Learning–Enabled Multimodal Fusion of Intra-Atrial and Body Surface Signals in Prediction of Atrial Fibrillation Ablation Outcomes
2022
Background: Machine learning is a promising approach to personalize atrial fibrillation management strategies for patients after catheter ablation. Prior atrial fibrillation ablation outcome prediction studies applied classical machine learning methods to hand-crafted clinical scores, and none have leveraged intracardiac electrograms or 12-lead surface electrocardiograms for outcome prediction. We hypothesized that (1) machine learning models trained on electrograms or electrocardiogram (ECG) signals can perform better at predicting patient outcomes after atrial fibrillation ablation than existing clinical scores and (2) multimodal fusion of electrogram, ECG, and clinical features can furt…
Performance Study of Split Ferrite Cores Designed for EMI Suppression on Cables
2020
The ideal procedure to start designing an electronic device is to consider the electromagnetic compatibility (EMC) from the beginning. Even so, EMC problems can appear afterward, especially when the designed system is interconnected with external devices. Thereby, electromagnetic interferences (EMIs) could be transmitted to our device from power cables that interconnect it with an external power source or are connected to another system to establish wired communication. The application of an EMI suppressor such as a sleeve core that encircles the cables is a widely used technique to attenuate EM disturbances. This contribution is focused on the characterization of a variation of this cable …
Selecting a small run-of-river hydropower plan by the analytic hierarchy process (AHP): A case study of Miño-Sil river basin, Spain
2015
Hydroelectric power is obtained by harnessing the potential energy of a mass of water flowing along a river bed to convert it first into mechanical and then into electrical energy. The system is therefore both clean and autonomous and has a high potential for development. A small hydropower plant has an installed power capacity of below 10 MW and is considered run-of-river when it diverts part of a river flow to generate its electricity. The use of multicriteria techniques in environmental decision making, including selecting between various alternatives, is important when it involves complex decisions in a number of disciplinary fields. The most widely used of these techniques is the analy…