Enhanced P2P Services Providing Multimedia Content

The retrieval facilities of most Peer-to-Peer (P2P) systems are limited to queries based on unique identifiers or small sets of keywords. Unfortunately, this approach is very inadequate and inefficient when a huge amount of multimedia resources is shared. To address this major limitation, we propose an original image and video sharing system, in which a user is able to interactively search interesting resources by means of content-based image and video retrieval techniques. In order to limit the network traffic load, maximizing the usefulness of each peer contacted in the query process, we also propose the adoption of an adaptive overlay routing algorithm, exploiting compact representations of the multimedia resources shared by each peer. Experimental results confirm the validity of the proposed approach, that is capable of dynamically adapting the network topology to peer interests, on the basis of query interactions among users

A Superstabilizing log⁡(n)\log(n)-Approximation Algorithm for Dynamic Steiner Trees

In this paper we design and prove correct a fully dynamic distributed algorithm for maintaining an approximate Steiner tree that connects via a minimum-weight spanning tree a subset of nodes of a network (referred as Steiner members or Steiner group) . Steiner trees are good candidates to efficiently implement communication primitives such as publish/subscribe or multicast, essential building blocks for the new emergent networks (e.g. P2P, sensor or adhoc networks). The cost of the solution returned by our algorithm is at most $\log |S|$ times the cost of an optimal solution, where $S$ is the group of members. Our algorithm improves over existing solutions in several ways. First, it tolerates the dynamism of both the group members and the network. Next, our algorithm is self-stabilizing, that is, it copes with nodes memory corruption. Last but not least, our algorithm is \emph{superstabilizing}. That is, while converging to a correct configuration (i.e., a Steiner tree) after a modification of the network, it keeps offering the Steiner tree service during the stabilization time to all members that have not been affected by this modification

Monitoring Wireless Sensor Networks through Logical Deductive Processes

This paper proposes a distributed multi-agent architecture for wireless sensor networks management, which exploits the dynamic reasoning capabilities of the Situation Calculus in order to emulate the reactive behavior of a human expert to fault situations. The information related to network events is generated by tunable agents installed on the network nodes and is collected by a logical entity for network managing where it is merged with general domain knowledge, with the aim of identifying the root causes of faults, and deciding on reparative actions. The logical inference system has being devised to carry out automated isolation, diagnosis, and, whenever possible, repair of network anomalies, thus enhancing the reliability, performance, and security of the network. To illustrate the advantages and potential benefits deriving from the reasoning capabilities of our management system, we also discuss an application scenario concerning the need of effectively coping with congestion arising in critical parts of the network

An Efficient Distributed Algorithm for Generating and Updating Multicast Trees

As group applications are becoming widespread, efficient network utilization becomes a growing concern. Multicast transmission represents a necessary lower network service for the wide diffusion of new multimedia network applications. Multicast transmission may use network resources more efficiently than multiple point-to-point messages; however, creating optimal multicast trees (Steiner Tree Problem in networks) is prohibitively expensive. This paper proposes a distributed algorithm for the heuristic solution of the Steiner Tree Problem, allowing the construction of effective distribution trees using a coordination protocol among the network nodes. Furthermore, we propose a novel distributed technique for dynamically updating the multicast tree. The approach proposed has been implemented and extensively tested both in simulation, and on experimental networks. Performance evaluation indicates that the distributed algorithm performs as well as the centralized version, providing good levels of convergence time and communication complexity

Robust data gathering for wireless sensor networks

2005 13th IEEE International Conference on Networks jointly held with the 2005 7th IEEE Malaysia International Conference on Communications, Proceedings Volume 1, 2005, Article number 1635527, Pages 469-474 2005 13th IEEE International Conference on Networks jointly held with the 2005 7th IEEE Malaysia International Conference on Communications; Kuala Lumpur; Malaysia; 16 November 2005 through 18 November 2005; Category number05EX1235; Code 69262 Robust data gathering for wireless sensor networks (Conference Paper) Ortolani, M. , Gatani, L. , Lo Re, G. Dipartimento di Ingegneria Informatica, Universit\ue0 degli Studi di Palermo, Viale delle Scienze Parco d'Orleans, 90128 Palermo, Italy View references (17) Abstract In this paper we propose a data gathering model for wireless sensor networks that provides a reasonable tradeoff between robustness and efficiency, with special regard to energy saving. We design a routing algorithm that exploits implicit acknowledgment of reception and smart caching of the data to implement an efficient strategy for retransmission of lost packets and alternative path discovery; in order to do that, we build upon the general framework presented in recent works, that provided a formulation of duplicate and order insensitive aggregation functions, taking advantage of some intrinsic characteristics of the wireless sensor networks. The advantages of the proposed approach become more evident when one parts from an ideal scenario in which all nodes have available data to transmit in favor of a more practical one in which data originates from only a subset of all sensors. In this practical case, the approach provides a better usage of the resources and a minimization of the traffic in the network, and, as a consequence, of the overall consumed energy

A monitoring framework exploiting the synergy between actual and virtual wireless sensors

This paper describes a framework that allows realistic monitoring of a wireless sensor network in order to assess its behavior before actually deploying all the nodes. Designing a wireless sensor network for a specific application typically involves a preliminary phase of simulations that rely on specialized software, whose behavior does not necessarily reproduce what will be experienced by an actual network. On the other hand, delaying the test phase until deployment may not be advisable due to unreasonable costs. This paper suggests the adoption of a hybrid approach that involves coupling an actual wireless sensor network composed of a minimal set of actual nodes with a simulated one; we describe a software platform that, by exploiting currently available wireless sensor networks technologies, implements a superimposed communication control network thus making this approach feasible. In order to demonstrate the advantages deriving from such approach, our framework will be validated on a specific scenario dealing with geophysical monitoring for avalanches preventio

Diseño de eco luminarias para espacios exteriores : reutilización de antenas de TV satelital y energía fotovoltáica

Ponencia en VIII Jornadas de Investigación y II Jornadas de Investigación de Becarios y Doctorandos Encuentro y Reflexión : investigación + transferencia + desarrolloLa Convención Marco de Naciones Unidas sobre el Cambio Climático (CMNUCC, 2015) en la XXI Conferencia Internacional sobre Cambio Climático celebrada en París en 2015 sentó bases de acciones tendientes a frenar la contaminación ambiental y el impacto negativo. Argentina adhiere al convenio y se propone una meta de reducción de sus emisiones de gases de efecto invernadero (GEI) un 15% en el año 2030 con respecto a las emisiones proyectadas en su Business as usual (BAU) al mismo año (INDC,2015). Una de estas acciones es la creación del programa Generacioón Eléctrica a partir de fuentes Renovables (GENREN), y la reglamentación de las Leyes 26.190 (2006) y 26.191 (2016) sobre el “Régimen de Fomento Nacional para el Uso de Fuentes Renovables de Energía destinadas a la Producción de Energía Eléctrica’. Se establece que en el plazo de 10 años, el 8% del consumo eléctrico tiene que ser abastecido a partir de fuentes de energías renovables.Fil: Sánchez, G. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Calvo, L. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gatani, M. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Gatani, M. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ávalos, S. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Molina, M. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin