950 resultados para Computational grids (Computer systems)


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La sociedad depende hoy más que nunca de la tecnología, pero la inversión en seguridad es escasa y los sistemas informáticos siguen estando muy lejos de ser seguros. La criptografía es una de las piedras angulares de la seguridad en este ámbito, por lo que recientemente se ha dedicado una cantidad considerable de recursos al desarrollo de herramientas que ayuden en la evaluación y mejora de los algoritmos criptográficos. EasyCrypt es uno de estos sistemas, desarrollado recientemente en el Instituto IMDEA Software en respuesta a la creciente necesidad de disponer de herramientas fiables de verificación formal de criptografía. En este trabajo se abordará la implementación de una mejora en el reductor de términos de EasyCrypt, sustituyéndolo por una máquina abstracta simbólica. Para ello se estudiarán e implementarán previamente dos máquinas abstractas muy conocidas, la Máquina de Krivine y la ZAM, introduciendo variaciones sobre ellas y estudiando sus diferencias desde un punto de vista práctico.---ABSTRACT---Today, society depends more than ever on technology, but the investment in security is still scarce and using computer systems are still far from safe to use. Cryptography is one of the cornerstones of security, so there has been a considerable amount of effort devoted recently to the development of tools oriented to the evaluation and improvement of cryptographic algorithms. One of these tools is EasyCrypt, developed recently at IMDEA Software Institute in response to the increasing need of reliable formal verification tools for cryptography. This work will focus on the improvement of the EasyCrypt’s term rewriting system, replacing it with a symbolic abstract machine. In order to do that, we will previously study and implement two widely known abstract machines, the Krivine Machine and the ZAM, introducing some variations and studying their differences from a practical point of view.

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En este Proyecto Fin de Grado se construirá una herramienta de gestión integral de centros hortícolas donde una serie de huertos cuidados por personas en situación de discapacidad son alquilados a terceros. Esta iniciativa se lleva a cabo gracias a la iniciativa “La Huerta de Montecarmelo” de la Fundación Carmen Pardo-Valcarce de Madrid. Este proyecto es el resultado de la colaboración entre la Escuela Técnica Superior de Ingeniería de Sistemas Informáticos y la Fundación, a través de un programa de Prácticas Externas que duró doce meses. Por una parte, tras años de trabajo en esta Obra Social, se encontró que muchos de los clientes, pasado el verano, se desvinculaban de las tareas y del medio. A fin de solucionar esos problemas, se propuso construir una aplicación web, comunicada con otros dispositivos, como Smartphones, permitiendo un flujo de trabajo más ágil y notificando a los arrendatarios de cada cambio en sus huertos, por ejemplo: fotos recientes, notificaciones de recolecta o futuros cursos. El proyecto se llevó a cabo con éxito a lo largo de 2012 y 2013. Abstract In this Final Degree Project we build a complete horticulture center management tool where a set of gardens, which are kept by people with disabilities, are leased to third parties. This project is carried out within the La Huerta Montecarmelo initiative of the Carmen Pardo-Valcarce Foundation in Madrid. The project was the result of collaboration between the School of Computer Systems Engineering of the Technical University of Madrid and that Foundation through an External Practices program that lasted twelve months. By one hand, over the years of Social Work in this initiative, it was found that some clients after spring were easily disconnected from the tasks involved to the garden. By the other, all the management of more than two hundred of gardens becomes a very complex task due to lots of paperwork. To solve these problems and more, we proposed to build a web application, relying on other devices, such as Smartphones, allowing a more agile workflow and notifying customers of any change related to its garden, for example: recent photographs, notifications of harvest or future courses. The project was successfully carried out throughout 2012 and 2013.

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En esta tesis se estudia la representación, modelado y comparación de colecciones mediante el uso de ontologías en el ámbito de la Web Semántica. Las colecciones, entendidas como agrupaciones de objetos o elementos con entidad propia, son construcciones que aparecen frecuentemente en prácticamente todos los dominios del mundo real, y por tanto, es imprescindible disponer de conceptualizaciones de estas estructuras abstractas y de representaciones de estas conceptualizaciones en los sistemas informáticos, que definan adecuadamente su semántica. Mientras que en muchos ámbitos de la Informática y la Inteligencia Artificial, como por ejemplo la programación, las bases de datos o la recuperación de información, las colecciones han sido ampliamente estudiadas y se han desarrollado representaciones que responden a multitud de conceptualizaciones, en el ámbito de la Web Semántica, sin embargo, su estudio ha sido bastante limitado. De hecho hasta la fecha existen pocas propuestas de representación de colecciones mediante ontologías, y las que hay sólo cubren algunos tipos de colecciones y presentan importantes limitaciones. Esto impide la representación adecuada de colecciones y dificulta otras tareas comunes como la comparación de colecciones, algo crítico en operaciones habituales como las búsquedas semánticas o el enlazado de datos en la Web Semántica. Para solventar este problema esta tesis hace una propuesta de modelización de colecciones basada en una nueva clasificación de colecciones de acuerdo a sus características estructurales (homogeneidad, unicidad, orden y cardinalidad). Esta clasificación permite definir una taxonomía con hasta 16 tipos de colecciones distintas. Entre otras ventajas, esta nueva clasificación permite aprovechar la semántica de las propiedades estructurales de cada tipo de colección para realizar comparaciones utilizando las funciones de similitud y disimilitud más apropiadas. De este modo, la tesis desarrolla además un nuevo catálogo de funciones de similitud para las distintas colecciones, donde se han recogido las funciones de (di)similitud más conocidas y también algunas nuevas. Esta propuesta se ha implementado mediante dos ontologías paralelas, la ontología E-Collections, que representa los distintos tipos de colecciones de la taxonomía y su axiomática, y la ontología SIMEON (Similarity Measures Ontology) que representa los tipos de funciones de (di)similitud para cada tipo de colección. Gracias a estas ontologías, para comparar dos colecciones, una vez representadas como instancias de la clase más apropiada de la ontología E-Collections, automáticamente se sabe qué funciones de (di)similitud de la ontología SIMEON pueden utilizarse para su comparación. Abstract This thesis studies the representation, modeling and comparison of collections in the Semantic Web using ontologies. Collections, understood as groups of objects or elements with their own identities, are constructions that appear frequently in almost all areas of the real world. Therefore, it is essential to have conceptualizations of these abstract structures and representations of these conceptualizations in computer systems, that define their semantic properly. While in many areas of Computer Science and Artificial Intelligence, such as Programming, Databases or Information Retrieval, the collections have been extensively studied and there are representations that match many conceptualizations, in the field Semantic Web, however, their study has been quite limited. In fact, there are few representations of collections using ontologies so far, and they only cover some types of collections and have important limitations. This hinders a proper representation of collections and other common tasks like comparing collections, something critical in usual operations such as semantic search or linking data on the Semantic Web. To solve this problem this thesis makes a proposal for modelling collections based on a new classification of collections according to their structural characteristics (homogeneity, uniqueness, order and cardinality). This classification allows to define a taxonomy with up to 16 different types of collections. Among other advantages, this new classification can leverage the semantics of the structural properties of each type of collection to make comparisons using the most appropriate (dis)similarity functions. Thus, the thesis also develops a new catalog of similarity functions for the different types of collections. This catalog contains the most common (dis)similarity functions as well as new ones. This proposal is implemented through two parallel ontologies, the E-Collections ontology that represents the different types of collections in the taxonomy and their axiomatic, and the SIMEON ontology (Similarity Measures Ontology) that represents the types of (dis)similarity functions for each type of collection. Thanks to these ontologies, to compare two collections, once represented as instances of the appropriate class of E-Collections ontology, we can know automatically which (dis)similarity functions of the SIMEON ontology are suitable for the comparison. Finally, the feasibility and usefulness of this modeling and comparison of collections proposal is proved in the field of oenology, applying both E-Collections and SIMEON ontologies to the representation and comparison of wines with the E-Baco ontology.

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The explosive growth of the traffic in computer systems has made it clear that traditional control techniques are not adequate to provide the system users fast access to network resources and prevent unfair uses. In this paper, we present a reconfigurable digital hardware implementation of a specific neural model for intrusion detection. It uses a specific vector of characterization of the network packages (intrusion vector) which is starting from information obtained during the access intent. This vector will be treated by the system. Our approach is adaptative and to detecting these intrusions by using a complex artificial intelligence method known as multilayer perceptron. The implementation have been developed and tested into a reconfigurable hardware (FPGA) for embedded systems. Finally, the Intrusion detection system was tested in a real-world simulation to gauge its effectiveness and real-time response.

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Abstract Mobile Edge Computing enables the deployment of services, applications, content storage and processing in close proximity to mobile end users. This highly distributed computing environment can be used to provide ultra-low latency, precise positional awareness and agile applications, which could significantly improve user experience. In order to achieve this, it is necessary to consider next-generation paradigms such as Information-Centric Networking and Cloud Computing, integrated with the upcoming 5th Generation networking access. A cohesive end-to-end architecture is proposed, fully exploiting Information-Centric Networking together with the Mobile Follow-Me Cloud approach, for enhancing the migration of content-caches located at the edge of cloudified mobile networks. The chosen content-relocation algorithm attains content-availability improvements of up to 500 when a mobile user performs a request and compared against other existing solutions. The performed evaluation considers a realistic core-network, with functional and non-functional measurements, including the deployment of the entire system, computation and allocation/migration of resources. The achieved results reveal that the proposed architecture is beneficial not only from the users’ perspective but also from the providers point-of-view, which may be able to optimize their resources and reach significant bandwidth savings.

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On cover: COO-1469-0046.

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"Supported in part by the Atomic Energy Commission under Contract no. US AEC AT(11-1) 1018."

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"July 5, 1965"

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Issued Mar. 1979.

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Thesis--George Washington University.

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Mode of access: Internet.

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"Sponsored jointly by the USAEC and Columbia University."