Artículos, informes y presentaciones en Congresos
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Acceso Abierto On the distortions in calculated GW parameters during slanted atmospheric soundings(2018) de la Torre, Alejandro; Alexander, Peter; Schmidt, Torsten; Llamedo, Pablo; Hierro, RodrigoThe significant distortions introduced in the measured atmospheric gravity wavelengths by soundings other than those in vertical and horizontal directions, are discussed as a function of the elevation angle of the sounding path and the gravity wave aspect ratio. Under- or overestimation of real vertical wavelengths during the measurement process depends on the value of these two parameters. The consequences of these distortions on the calculation of the energy and the vertical flux of horizontal momentum are analyzed and discussed in the context of two experimental limb satellite setups: GPSLEO radio occultations and TIMED/SABER ((Atmosphere using Broadband Emission Radiometry/Thermosphere– Ionosphere–Mesosphere–Energetics and Dynamics)) measurements. Possible discrepancies previously found between the momentum flux calculated from satellite temperature profiles, on site and from model simulations, may to a certain degree be attributed to these distortions. A recalculation of previous momentum flux climatologies based on these considerations seems to be a difficult goal. - Artículo
Acceso Abierto Tendencies in multi-agent systems: a systematic literature review(2020) Falco, Mariana; Robiolo, GabrielaThe application of Artificial Intelligence mechanisms allows the development of systems capable to solve very complex engineering problems. Multi-agent systems (MAS) are one paradigm that allows an alternative way to design distributed control systems. While research in this area grew exponentially before 2009, there is a need to understand the status quo of the field from 2009 to June 2017. An extension of the results of a SLR related to Multi-Agent Systems, its applications and research gaps, following Kitchenham and Wholin guidelines are presented in this paper. From the analysis of 279 papers (out of 3522 candidates), our findings suggest that: a) there were 20 gaps related to agent-oriented methodologies; coordination, cooperation and negotiation; modelling, developing, testing and debugging; b) 24 gaps related to specific domains (recycling, dynamic evacuation, hazard management, health-care, industry, logistics and manufacturing, machine learning, ambient assisted living); and 14 gaps related to specific areas within MAS (A-Teams, dynamic MAS and mobile agents, ABMS, evolutionary MAS, and self-organizing MAS). These gaps specify lines of research where the MAS community must work to achieve the unification of the agent-oriented paradigm; as well as strengthen ties with the industry. - Artículo
Acceso Abierto Using Convective Available Potential Energy (CAPE) and Dew-Point Temperature to Characterize Rainfall-Extreme Events in the South-Central Andes(2019) Ramezani Ziarani, Maryam; Bookhagen, Bodo; Schmidt, Torsten; Wickert, Jens; de la Torre, Alejandro; Hierro, RodrigoThe interactions between atmosphere and steep topography in the eastern south–central Andes result in complex relations with inhomogenous rainfall distributions. The atmospheric conditions leading to deep convection and extreme rainfall and their spatial patterns—both at the valley and mountain-belt scales—are not well understood. In this study, we aim to identify the dominant atmospheric conditions and their spatial variability by analyzing the convective available potential energy (CAPE) and dew-point temperature (Td). We explain the crucial effect of temperature on extreme rainfall generation along the steep climatic and topographic gradients in the NW Argentine Andes stretching from the low-elevation eastern foreland to the high-elevation central Andean Plateau in the west. Our analysis relies on version 2.0 of the ECMWF’s (European Centre for Medium-RangeWeather Forecasts) Re-Analysis (ERA-interim) data and TRMM (Tropical Rainfall Measuring Mission) data. We make the following key observations: First, we observe distinctive gradients along and across strike of the Andes in dew-point temperature and CAPE that both control rainfall distributions. Second, we identify a nonlinear correlation between rainfall and a combination of dew-point temperature and CAPE through a multivariable regression analysis. The correlation changes in space along the climatic and topographic gradients and helps to explain controlling factors for extreme-rainfall generation. Third, we observe more contribution (or higher importance) of Td in the tropical low-elevation foreland and intermediate-elevation areas as compared to the high-elevation central Andean Plateau for 90th percentile rainfall. In contrast, we observe a higher contribution of CAPE in the intermediate-elevation area between low and high elevation, especially in the transition zone between the tropical and subtropical areas for the 90th percentile rainfall. Fourth, we find that the parameters of the multivariable regression using CAPE and Td can explain rainfall with higher statistical significance for the 90th percentile compared to lower rainfall percentiles. Based on our results, the spatial pattern of rainfall-extreme events during the past 16 years can be described by a combination of dew-point temperature and CAPE in the south–central Andes. - Artículo
Acceso Abierto 11 Years of Rayleigh Lidar Observations of Gravity Wave Activity Above the Southern Tip of South America(2019) Llamedo, Pablo; Salvador, J.; de la Torre, Alejandro; Quiroga, J.; Alexander, P.; Hierro, Rodrigo; Schmidt, T.; Pazmiño, A.; Quel, E.Gravity wave (GW) activity is analyzed using temperature (T) data retrieved from a Rayleigh light detection and ranging (lidar) at Río Gallegos, Argentina (51.6°S, 69.3°W). GW characteristics are derived from 302 nights of observations providing more than 1,018 hr of high-resolution lidar data between 20- and 56-km height from August 2005 to December 2015. T measurements are performed by a Differential Absorption Lidar instrument. This lidar was the southernmost outside Antarctica until the end of 2017. Río Gallegos is an exceptional place to observe large amplitude GW. Every lidar measurement is classified according to its relative position to the polar vortex. The lidar measurements are compared with collocated Sounding of the Atmosphere using Broadband Emission Radiometry and Global Positioning System-Radio Occultation data. The different instruments show different windows of the GW spectrum, providing complementary observations. In general, the geometric mean of the specific GW potential energy (PE) is larger during winter and spring than during summer and autumn. The largest geometric mean of PE is found inside the vortex and decreases monotonically at its edge, outside it and when there is no vortex. The same behavior is observed with satellite data. On average, it can be seen that lidar observations provide larger PE values than limb sounding measurements. From a Morlet continuous wavelet transform analysis, three distinct modes are captured from Sounding of the Atmosphere using Broadband Emission Radiometry and from Global Positioning System-Radio Occultation data at the upper and lower stratosphere, respectively. In particular, a systematic 3.5- to 4-year oscillation, possibly related to El Niño–Southern Oscillation is observed. - Artículo
Acceso Abierto Measuring The Distance Between High-Level Models In A Reengineering Process(2019) Cassol, Ignacio; Berdiñas, Ignacio; Arévalo, GabrielaWhen refactoring high-level models, measuring the differences between the original and the refactored model helps the designers know how the original model was modified and if the transformation added more complexity or/and improved the model. In our previous work, we developed the M2K methodology that parses legacy C code, maps it in a high-level model to represent the domain concepts and proposes a refactored model to improve the mapped design. Based on both models, we propose a distance to indicate, from the domain viewpoint, if the original identified concept keeps the same structure or, conversely, if the refactorings modify the concepts represented in the original model. Our approach is based on models generated through the M2K methodology and does not take into account syntactical variations between models. To show the applicability and the validation of our approach, firstly we show how we apply it on a trivial case study. Then, we show the results of applying our proposal to thirteen case studies (small-scale real projects implemented in C) that were also used to validate the M2K methodology. - Documento de conferencia
Acceso Abierto Utilización del método geoeléctrico para la detección de túneles(2018) Bongiovanni, María VictoriaEl presente trabajo consiste en una aplicación de un método geofísico a sitios urbanos. Debido al carácter no invasivo de estos métodos, son especialmente adecuados para estudiar el patrimonio cultural resguardándolo. Por este motivo es que se están utilizando cada vez más en la caracterización de sitios arqueológicos y otras estructuras subterráneas (Batayneh, 2011; Drahor, 2011; entre otros). Detectar túneles es generalmente difícil y más aún cuando se encuentran en un sitio urbano. Diversos métodos geofísicos han sido utilizados solos o combinados, con variada efectividad, dependiendo de las características del suelo y del contraste con los materiales que forman el túnel, su profundidad y estado de conservación y las condiciones ambientales de la superficie (Martínez Lorenzo y otros, 2011; Banks, 2012; entre otros). Los métodos geofísicos más frecuentemente utilizados para la arqueología urbana son el radar (GPR, por sus siglas en inglés: groundpenetrating radar) (Leucci & Negri, 2006; Bonomo et al., 2012), el magnético (Eppelbaum, 2011; entre otros) y la tomografía eléctrica resistiva (ERT, por sus siglas en inglés); (Tsokas et al., 2011; entre otros). En particular, para realizar este trabajo utilizamos el método geoeléctrico. Este método ilus- tra la distribución de resistividad eléctrica del subsuelo a partir de mediciones realizadas con electrodos ubicados sobre el terreno. El objetivo de este trabajo es la localización y posible caracterización de túneles en el Parque Avellaneda. Se cree que los túneles fueron construidos a mediados del siglo XIX. Salen de la “Casona de los Olivera”, llamada posteriormente “Chacra de los Remedios”. En particular, estamos interesados en localizar un supuesto túnel que se dirige hacia “Villa Ambato” (actualmente una escuela Técnica). Se cree que este túnel servía de paso secreto entre estas dos construcciones, pues eran de las pocas existentes en un lugar de chacras alejadas de los límites de la ciudad. - Documento de conferencia
Acceso Abierto Sistema dinámico y adaptativo para el control del tráfico de una intersección de calles: modelación y simulación de un sistema multi-agente(2018) Fernandez Battolla, Tomás; Fuentes, Santiago; Illi, José Ignacio; Nacht, Joaquín; Falco, Mariana; Pezzuchi, Gastón; Robiolo, GabrielaEs frecuente la pérdida de tiempo de los conductores y los embotellamientos de tráfico en las ciudades, por una configuración no óptima de los semáforos. Diversos dominios han intentado comprender el fenómeno e identificar las causas en pos de obtener una solución apropiada. El presente trabajo introduce un algoritmo cuyo fin es reducir el tiempo de espera de los conductores en una intersección. Para lo cual, la validación fue llevada a cabo en tres escenarios posibles, definidos por medio de la variación de la frecuencia de los autos. El entorno de simulación se implementó en NetLogo, lo que permitió estudiar el impacto del cambio de luces a través de la simulación de semáforos de tiempos fijos vs semáforos con control inteligente mediante agentes. Hemos obtenido una reducción máxima del 45% en el tiempo de espera. Finalmente, presentaremos las conclusiones y el trabajo futuro.