Optimal Fourier filtering of a function that is strictly confined within a sphere

We present an alternative method to filter a distribution, that is strictly confined within a sphere of given radius $r_c$, so that its Fourier transform is optimally confined within another sphere of radius $k_c$. In electronic structure methods, it can be used to generate optimized pseudopotentials, pseudocore charge distributions, and pseudo atomic orbital basis sets.Comment: 3 pages, 2 figure

Magnetism of two-dimensional defects in Pd: stacking faults, twin boundaries and surfaces

Careful first-principles density functional calculations reveal the importance of hexagonal versus cubic stacking of closed packed planes of Pd as far as local magnetic properties are concerned. We find that, contrary to the stable face centered cubic phase, which is paramagnetic, the hexagonal close-packed phase of Pd is ferromagnetic with a magnetic moment of 0.35 $\mu_{B}$/atom. Our results show that two-dimensional defects with local hcp stacking, like twin boundaries and stacking faults, in the otherwise fcc Pd structure, increase the magnetic susceptibility. The (111) surface also increases the magnetic susceptibility and it becomes ferromagnetic in combination with an individual stacking fault or twin boundary close to it. On the contrary, we find that the (100) surface decreases the tendency to ferromagnetism. The results are consistent with the magnetic moment recently observed in small Pd nanoparticles, with a large surface area and a high concentration of two-dimensional stacking defects.Comment: 8 pages, 10 figure

Nuevas metodologías para las simulaciones ab initio y su aplicación en el crecimiento de hilos de oro monoatómicos con impurezas

Tesis doctoral inédita leida en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura:20-10-200

Detección y caracterización por tamaños de micro y nanoplásticos en muestras de interés ambiental

El uso indiscriminado de plásticos, conlleva a que la mayoría acaben en la naturaleza, donde son capaces de degradarse, creando partículas muy pequeñas, los microplásticos, y a su vez formando nanoplásticos, lo que los hace cada vez más peligrosos, tanto para la salud humana y animal como para la propia naturaleza. Por ello es necesario disponer de metodologías analíticas para su detección, identificación y cuantificación.Este trabajo ha consistido en primer lugar, en recopilar información de actualidad relacionada con las distintas técnicas y procedimientos que existen para la preconcentración, aislamiento, separación, identificación y caracterización de micro- y nanoplásticos, así como nuevas técnicas o estrategias que pueden ser prometedoras en un futuro próximo, profundizando en la técnica de fraccionamiento en flujo mediante campo de flujo asimétrico (AF4).En segundo lugar, se ha realizado un estudio sobre el procedimiento experimental óptimo para la identificación de micro- y nanoplásticos (empleando partículas de poliestireno) mediante la tinción con Rojo Nilo (tinte orgánico) para su posterior detección mediante fluorescencia molecular y EAM UV-vis. Demostrando que puede ser una estrategia útil para la detección y caracterización por tamaños de nanoplásticos en análisis de rutina.<br /

Fault Diagnosis of Electric Transmission Lines Using Modular Neural Networks

"(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, 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 components of this work in other works."This paper proposes a new method for fault diagnosis in electric power systems based on neural networks. With this method the diagnosis is performed by assigning a neural module for each type of component of the electric power system, whether it is a transmission line, bus or transformer. The neural modules for buses and transformers comprise two diagnostic levels which take into consideration the logic states of switches and relays, both internal and back-up. The neural module for transmission lines also has a third diagnostic level which takes into account the oscillograms of fault voltages and currents, as well as the frequency spectrums of these oscillograms, in order to verify if the transmission line had in fact been subjected to a fault. One important advantage of the diagnostic system proposed is that its implementation does not require the use of a network configurator for the system; it does not depend on the size of the power network, nor does it require retraining of the neural modules if the power network increases in size, making its application possible to only one component, a specific area, or the whole context of the power system..Flores, A.; Quiles Cucarella, E.; García Moreno, E.; Morant Anglada, FJ. (2016). Fault Diagnosis of Electric Transmission Lines Using Modular Neural Networks. IEEE Latin America Transactions. 14(8):3663-3668. doi:10.1109/TLA.2016.7786348S3663366814

Predictive Diagnosis Based on Predictor Symptoms for Isolated Photovoltaic Systems Using MPPT Charge Regulators

[EN] In this work, new results are presented on the implementation of predictive diagnosis techniques on isolated photovoltaic (PV) systems and installations. The novelties introduced in this research focus on the additional advantages obtained from the point of view of predictive diagnosis of faults caused by partial shading in isolated PV installations using maximum power point tracking (MPPT) regulators. MPPT regulators are comparatively more appropriate than pulse width modulation (PWM) solar regulators in order to implement fault diagnosis systems. MPPT regulators have a physical separation between the electrical parameters belonging to the part of the solar panel with respect to the batteries part. Therefore, these electrical parameters can be used to obtain early predictive symptoms of the effects of partial shading with a greater level of observation and sensitivity. Additionally, modifications are proposed in the PV system assembly to obtain greater homogeneity of all the panels regarding the solar irradiance reception angle.García Moreno, E.; Quiles Cucarella, E.; Correcher Salvador, A.; Morant Anglada, FJ. (2022). Predictive Diagnosis Based on Predictor Symptoms for Isolated Photovoltaic Systems Using MPPT Charge Regulators. Sensors. 22(20):1-33. https://doi.org/10.3390/s22207819133222

Benchmarking the power of amateur observatories for TTV exoplanets detection

This document is the Accepted Manuscript version of the following article: Roman v. Baluev, et al, ‘Benchmarking the power of amateur observatories for TTV exoplanets detection’, Monthly Notices of the Royal Astronomical Society, Vol. 450(3): 3101-3113, first published online 9 May 2015. The version of record is available at doi: https://doi.org/10.1093/mnras/stv788 © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We perform an analysis of ~80000 photometric measurements for the following 10 stars hosting transiting planets: WASP-2, -4, -5, -52, Kelt-1, CoRoT-2, XO-2, TrES-1, HD 189733, GJ 436. Our analysis includes mainly transit lightcurves from the Exoplanet Transit Database, public photometry from the literature, and some proprietary photometry privately supplied by other authors. Half of these lightcurves were obtained by amateurs. From this photometry we derive 306 transit timing measurements, as well as improved planetary transit parameters. Additionally, for 6 of these 10 stars we present a set of radial velocity measurements obtained from the spectra stored in the HARPS, HARPS-N, and SOPHIE archives using the HARPS-TERRA pipeline. Our analysis of these TTV and RV data did not reveal significant hints of additional orbiting bodies in almost all of the cases. In the WASP-4 case, we found hints of marginally significant TTV signals having amplitude 10-20 sec, although their parameters are model-dependent and uncertain, while radial velocities did not reveal statistically significant Doppler signals.Peer reviewe

Alarm sequences for fault detection and diagnosis

En este artículo se habla de las secuencias de las alarmas de una planta industrial y cómo pueden ser utilizadas para detectar y diagnosticar fallos. Este trabajo parte del Gerenciamiento de Alarmas, un tema que busca reducir el número de alarmas desplegadas a los operadores, contribuyendo a la apropiada detección y diagnóstico de fallos. Se muestran algunas técnicas de búsqueda cuya aplicación se mostrará posteriormente en un conjunto de datos asociados a un fallo real de una planta de Cracking Catalítico Fluidizado, para hallar la secuencia de las alarmas asociada al fallo en cuestión. Se muestra una metodología clara para poder hallar dichas secuencias de alarmas. Al final se enumeran algunas conclusiones relacionadas con la limitación debido al período de muestreo de las alarmas, y al uso de un diccionario de fallos extendido para incorporar la secuencia de las alarmas dentro de otras técnicas para la detección y el diagnóstico de fallos.This article talks about the alarm sequences of an industrial plant and how They can be used to detect and diagnose faults. This work is part of Alarm Management, a topic that seeks to reduce the number of alarms displayed operators, contributing to the proper detection and diagnosis of faults. I know show some search techniques whose application will be shown later in a data set associated with a real failure of a Catalytic Cracking plant Fluidized, to find the sequence of alarms associated with the fault in question. I know shows a clear methodology to be able to find these alarm sequences. In the end it list some conclusions related to the limitation due to the period of alarm sampling, and the use of an extended fault dictionary to incorporate the sequencing of alarms within other techniques for the detection and diagnosis of failures

Secuencias de alarmas para detección y diagnóstico de fallos

En este artículo se habla de las secuencias de las alarmas de una planta industrial y cómo pueden ser utilizadas para detectar y diagnosticar fallos. Este trabajo parte del Gerenciamiento de Alarmas, un tema que busca reducir el número de alarmas desplegadas a los operadores, contribuyendo a la apropiada detección y diagnóstico de fallos. Se muestran algunas técnicas de búsqueda cuya aplicación se mostrará posteriormente en un conjunto de datos asociados a un fallo real de una planta de Cracking Catalítico Fluidizado, para hallar la secuencia de las alarmas asociada al fallo en cuestión. Se muestra una metodología clara para poder hallar dichas secuencias de alarmas. Al final se enumeran algunas conclusiones relacionadas con la limitación debido al período de muestreo de las alarmas, y al uso de un diccionario de fallos extendido para incorporar la secuencia de las alarmas dentro de otras técnicas para la detección y el diagnóstico de fallos

Systematic generation of finite-range atomic basis sets for linear-scaling calculations

Basis sets of atomic orbitals are very efficient for density functional calculations but lack a systematic variational convergence. We present a variational method to optimize numerical atomic orbitals using a single parameter to control their range. The efficiency of the basis generation scheme is tested and compared with other schemes for multiple zeta basis sets. The scheme shows to be comparable in quality to other widely used schemes albeit offering better performance for linear-scaling computations