Examinando por Materia "GEOMETRIA"
Mostrando 1 - 3 de 3
Resultados por página
Opciones de ordenación
Artículo de Publicación Periódica An algebra for OLAP(2017) Kuijpers, Bart; Vaisman, Alejandro Ariel"Online Analytical Processing (OLAP) comprises tools and algorithms that allow querying multidimensional databases. It is based on the multidimensional model, where data can be seen as a cube, where each cell contains one or more measures can be aggregated along dimensions. Despite the extensive corpus of work in the field, a standard language for OLAP is still needed, since there is no well-defined, accepted semantics, for many of the usual OLAP operations. In this paper, we address this problem, and present a set of operations for manipulating a data cube. We clearly define the semantics of these operations, and prove that they can be composed, yielding a language powerful enough to express complex OLAP queries. We express these operations as a sequence of atomic transformations over a fixed multidimensional matrix, whose cells contain a sequence of measures. Each atomic transformation produces a new measure. When a sequence of transformations defines an OLAP operation, a flag is produced indicating which cells must be considered as input for the next operation. In this way, an elegant algebra is defined. Our main contribution, with respect to other similar efforts in the field is that, for the first time, a formal proof of the correctness of the operations is given, thus providing a clear semantics for them. We believe the present work will serve as a basis to build more solid practical tools for data analysis."Artículo de Publicación Periódica A geometrical view of scalar modulation instability in optical fibers(2017) Hernández, Santiago M.; Fierens, Pablo Ignacio; Sánchez, Alfredo D.; Grosz, Diego; Bonetti, Juan I."Full models of scalar modulation instability (MI) in optical fibers available in the literature usually involve complex formulations. In this paper, we present a novel approach to the analysis of MI in optical fibers by means of a simple geometrical description in the power versus frequency plane. This formulation allows us to relate the shape of the MI gain to any arbitrary dispersion profile of the medium, thus providing a simple insight. As a result, we derive a straightforward explanation of the nontrivial dependence of the cutoff power on high-order dispersion and explicitly derive the power that maximizes the gain. Our approach puts forth a tool to synthesize a desired MI gain with the potential application to a number of parametric-amplification and supercontinuum-generation devices whose initialstage dynamics rely upon MI."Proyecto final de Grado Simulación de partículas activas con geometría definida por esfero-polígonos(2021-04-07) Vega, Magdalena; Guido, Sebastián; Parisi, Daniel"Se implementó una plataforma para realizar simulaciones de descargas de partículas autopropulsadas de recintos de geometría arbitraria y con partículas con forma de esferopolígonos que también se pueden definir por el usuario. Como caso de estudio, se analizó el problema de partículas cuadradas atravesando una apertura angosta. Se estudió la influencia de los principales parámetros del modelo (resistencia a la rotación, amplitud del ruido angular, velocidad de autopropulsión de las partículas y ancho de la apertura del recinto) en el caudal de salida y la distribución de los tiempos de salida entre partículas consecutivas. En particular, a partir de la distribución de estos tiempos de evacuación se alinean los resultados con una ley de potencia, lo que concuerda con observaciones experimentales."