13,390 research outputs found
Rango numérico de productos conmutativos
No full textEl rango numérico de un operador lineal T en un espacio de Hilbert H con producto interno and lt; , and gt; es el subconjunto de C dada po
Desigualdades rango lineales en 5 variables
No full textEn este trabajo se hace un estudio de las desigualdades rango lineales, encontradas por R. Dougherty, C. Freiling y K. Zeger, las cuales involucran 5 variables, ´estas, junto a las desigualdades polimatroides y de Ingleton verifican que, las funciones rango lineales en 5 variables determinan un cono convexo poli´edrico. Adem´as, se estudia la caracterizaci´on de estas funciones involucrando hasta 4 variables, donde solo las desigualdades polimatroides y de Ingleton, logran caracterizarlas. Se estudia tambi´en algunas relaciones entre las desigualdades de la informaci´on tipo Shannon y las funciones polimatroides, a su vez las relaciones de las funciones entr´opicas, funciones polimatroides y las funciones rango lineal. Este trabajo se basa en [2],[4],[5] y [12]. (Texto tomado de la fuente)Abstract. This paper makes a study on linear rank inequalities, found by R. Dougherty, C. Freiling y K. Zeger, involve five variables, these, together with the Shannon-type and Ingleton inequalities verified that, linear rank functions on five variables determine a polyhedral convex cone. We also present a study of the characterization of these functions involving up to 4 variables, where only the polymatroid and Ingleton inequalities, achieve characterize. Also it is studied some relationships between the Shannon-type information inequalities and polymatroid functions, moreover relationships between entropic functions, polymatroid functions and linear rank functions. This paper is based on [2],[4],[5] and [12].Maestrí
Expansión del rango de la paloma coroniblanca columba leucocephala al territorio continental de Colombia
No full textEntre las 32 especies de la familia Columbidae anotadas para Colombia, Hilty and amp; Brown (1986) incluyeron a la Paloma Coroniblanca Columba leucocephala L. como restringida al archipiélago de San Andrés y Providencia. Esta especie, de amplia distribución en las Antillas, ha sido registrada en algunas islas continentales o localidades costeras en el sur de la Florida, Costa Rica y Panamá (Bond 1950, 1961, Wetmore 1968, Stiles and amp; Skutch 1989). En Colombia C leucocephala fue encontrada en las islas de San Bernardo, a menos de 30 km del litoral Caribe del Departamento de Sucre (9° 40'Norte, 75° 45'Oeste) en 1980 y 1981 por Moreno and amp; López (1982), hallazgo que no fue reseñado en la literatura ornitológica de amplia circulación. En esta nota formalizamos la ampliación del rango geográfico de esta especie al territorio continental colombiano, agregando registros adicionales recientes
El Rango de una Matriz
No full textSe introduce el concepto de rango de una matriz y se muestra el método para calcularlo aplicando operaciones elementales, proporcionando varios ejemplos. Además, se exponen algunas de las propiedades básicas del rango de una matriz.https://media.upv.es/player/?id=3b072f00-3657-11e6-83a3-836b8c4692beCorral Ortega, C. (2016). El Rango de una Matriz. https://riunet.upv.es/handle/10251/66553DE
A Predictive Cross-Layered Interference Management in a Multichannel MAC with Reactive Routing in VANET
No full textVehicular ad hoc networks (VANETs) represent a particular mobile technology that permits communication between vehicles, offering security and comfort. Nowadays, distributed mobile wireless computing is becoming a very important communication paradigm, due to its flexibility to adapt to different mobile applications. In this work, an interference aware metric is proposed in order to reduce the level of interference between each pair of nodes at the MAC and routing layer. In particular, this metric with a prediction algorithm is proposed to work in a cross-layered MAC and an on-demand routing scheme in multi-radio vehicular networks, wherein each node is equipped with two multi-channel radio interfaces. The proposed metric is based on the maximization of the average signal-to-interference ratio (SIR) level of the connection between source and destination. In order to relieve the effects of the co-channel interference perceived by mobile nodes, transmission channels are switched on a basis of a periodical SIR evaluation. Our solution has been integrated with an on-demand routing scheme but it can be applied to other routing strategies. Three on-demand interference aware routing schemes integrating IEEE 802.11p Multi-channel MAC have been tested to assess the benefits of the novel metric applied to a vehicular context. NS-3 has been used for implementing and testing the proposed idea, and significant performance improvements were obtained: in particular, the proposed policy has resulted in an enhancement of network performance in terms of throughput and packet delivery ratio
A new interference aware on demand routing protocol for vehicular networks
No full textVehicular communication systems represent one of the most desirable technologies when the safety, efficiency and comfort of everyday road travel need to be improved. The main advantage is the absence of an infrastructure, typical of centralized networks, that makes them very scalable and adequate for highly-variable network topologies. On the other hand, communication protocols become very complex and, sometimes, signaling overhead may waste bandwidth availability. Vehicular Ad-hoc NETworks (VANETs) are able to provide wireless networking capability in situations where no fixed infrastructure exists and the communication among nodes can be either direct or made via relaying nodes, as in the classical ad-hoc networks. In order to relieve the effects of the co-channel interference perceived by mobile nodes, transmission channels are switched on a basis of a periodical Signal-to-Interference Ratio (SIR) evaluation. The attention is focused on the routing level of VANET and we propose an interference aware routing scheme for multi-radio vehicular networks, wherein each node is equipped with a multi-channel radio interface. A new metric is also proposed, based on the maximization of the average SIR level of the connection between source and destination. Our solution has been integrated with the AODV routing protocol to design an enhanced Signal-to-Interference- Ratio-AODV (SIR-AODV). NS-2 has been used for implementing and testing the proposed idea, and significant performance enhancements were obtained, in terms of throughput, packet delivery and, obviously, interference. © 2011 Society for Modeling & Simu
Rango asociado a una curva proyectiva
No full textEn este trabajo se estudia la noción de rango asociado a una curva C ⊂ Pn no degenerada y no singular. En el caso en que C ⊂ Pd es la curva de Veronese de grado d, la definición de rango se relaciona con el rango de formas binarias. Se caracterizan todos los conjuntos de puntos formas de rango constante y se da un algoritmo para calcular el rango de una forma. Para C una curva de género g ≥ 1, inmersa en Pn por el sistema lineal completo asociado a un fibrado lineal no especial, se caracterizan algunos de los conjuntos de puntos de rango constante y se dan cotas óptimas para el rango (que dependen del grado del fibrado lineal). En el caso en que C es una curva elíptica (esto es g = 1) se relacionan los resultados obtenidos con la “Plane Secant Formula” y una variante de esta, que son fórmulas enumerativas de planos multisecantes y multitangentes de curvas.In this work we study the notion of rank associated to a nonsingular and nondegenerated curve C ⊂ Pn. In the case where C ⊂ Pd is the Veronese curve of degree d, the definition of rank is related with the rank of binary forms. We characterize the sets of forms having constant rank and we give an algorithm to determine the rank of a form. For C a curve of genus g ≥ 1 inmersed in Pn by the complete linear system associated to a nonspecial line bundle, we describe some of the sets of points having constant rank and we give optimal bounds for the rank (which depend on the degree of the line bundle). In the case where C is an elliptic curve (ie. g = 1), we relate the results to the “Plane Secant Formula” and a variant of it, which are enumerative formulas for multisecant and multitangent planes of curves.Fil: Comas, Gonzalo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
A new channel assignment scheme for interference-aware routing in vehicular networks
No full textMobile computing and vehicular communications are becoming a very important paradigm for wireless communications, mainly because of their ability to adapt to different mobile applications. In this paper, we propose a new scheme for reducing the interference level during mobile transmissions in the VehiculAr inter-NETworking (VANET) environment, taking the advantage of the multi-channel nature of IEEE802.11p standard. In order to relieve the effects of the cochannel interference perceived by mobile nodes, transmission channels are switched on a basis of a periodical Signal-to- Interference Ratio (SIR) evaluation. The attention is focused on the routing level of VANET and we propose an interference aware routing scheme for multi-radio vehicular networks, wherein each node is equipped with a multi-channel radio interface. A new metric is also proposed, based on the maximization of the average SIR level of the connection between source and destination. Our solution has been integrated with the AODV routing protocol to design an enhanced Signal-to- Interference-Ratio-AODV (SIR-AODV). NS-2 has been used for implementing and testing the proposed idea, and significant performance enhancements were obtained, in terms of throughput, packet delivery and, obviously, interference. ©2011 IEEE © 2011 IEEE
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