Browsing by Author "Cortes, C."
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- ItemConstraints on Helium Enhancement in the Globular Cluster M4 (NGC 6121) : The Horizontal Branch Test(2014) Valcarce Bravo, Aldo Alfonso Raúl; Catelan, Márcio; Alonso García, J.; Cortes, C.; De Medeiros, J. R.
- ItemEnergy evaluation of different inverter topologies and modulations used on electrical vehicles(IEEE, 2015) Naranjo, W.; Pereda Torres, Javier Eduardo; Muñoz, L. E.; Cortes, C.This paper evaluates different inverter topologies and modulations, which use hard switching techniques applied to an electric powertrain to reduce inverter losses. Three inverter topologies and three modulation techniques are evaluated through a simulation. Some inverter configurations are in research level and not used commercially on powertrains yet, but are studied to contrast its energy-efficiency advantages. The methodology proposed simulates and evaluates the powertrain behavior that uses one permanent magnet synchronous motor with a field oriented controller, with an ECE-15 driving cycle. This methodology uses a multi-disciplinary analysis scheme that combines the vehicle dynamics with the electric powertrain. Then, the total harmonic distortion and the power losses are compared. As a result, different indicators allow suggesting an inverter configuration that extends driving autonomy.
- ItemOxidative stabilization of palm olein with isoespintanol (2-isopropyl-3,6-dimethoxy-5-methylphenol) isolated from Oxandra cf xylopioides.(2017) Zapata, K.; Arias, J. P.; Cortes, C.; López Alarcón, Camilo Ignacio; Durango Restrepo, D.; Rojano, B.
- ItemThe VVV Infrared Variability Catalog (VIVA-I)(2020) Ferreira Lopes, E. C.; Cross, N. J. G.; Catelan, M.; Minniti, D.; Hempel, M.; Lucas, W. P.; Angeloni, R.; Jablonsky, F.; Braga, F. V.; Leao, C. I.; Herpich, F. R.; Alonso-Garcia, J.; Papageorgiou, A.; Pichara, K.; Saito, K. R.; Bradley, A.; Beamin Muhlenbrock Juan Carlos; Cortes, C.; De Medeiros, J. R.; Russell, ChristopherThanks to the VISTA Variables in the Via Lactea (VVV) ESO Public Survey it is now possible to explore a large number of objects in those regions. This paper addresses the variability analysis of all VVV point sources having more than 10 observations in VVVDR4 using a novel approach. In total, the near-IR light curves of 288,378,769 sources were analysed using methods developed in the New Insight Into Time Series Analysis project. As a result, we present a complete sample having 44, 998, 752 variable star candidates (VVV-CVSC), which include accurate individual coordinates, near-IR magnitudes (ZYJHKs), extinctions A(Ks), variability indices, periods, amplitudes, among other parameters to assess the science. Unfortunately, a side effect of having a highly complete sample, is also having a high level of contamination by non-variable (contamination ratio of non-variables to variables is slightly over 10:1). To deal with this, we also provide some flags and parameters that can be used by the community to de-crease the number of variable candidates without heavily decreasing the completeness of the sample. In particular, we cross-identified 339,601 of our sources with Simbad and AAVSO databases, which provide us with information for these objects at other wavelegths. This sub-sample constitutes a unique resource to study the corresponding near-IR variability of known sources as well as to assess the IR variability related with X-ray and Gamma-Ray sources. On the other hand, the other 99.5% sources in our sample constitutes a number of potentially new objects with variability information for the heavily crowded and reddened regions of the Galactic Plane and Bulge. The present results also provide an important queryable resource to perform variability analysis and to characterize ongoing and future surveys like TESS and LSST.