798 resultados para cryptographic protocol


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In wireless sensor networks, the routing algorithms currently available assume that the sensor nodes are stationary. Therefore when mobility modulation is applied to the wireless sensor networks, most of the current routing algorithms suffer from performance degradation. The path breaks in mobile wireless networks are due to the movement of mobile nodes, node failure, channel fading and shadowing. It is desirable to deal with dynamic topology changes with optimal effort in terms of resource and channel utilization. As the nodes in wireless sensor medium make use of wireless broadcast to communicate, it is possible to make use of neighboring node information to recover from path failure. Cooperation among the neighboring nodes plays an important role in the context of routing among the mobile nodes. This paper proposes an enhancement to an existing protocol for accommodating node mobility through neighboring node information while keeping the utilization of resources to a minimum.

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In this paper we propose a cryptographic transformation based on matrix manipulations for image encryption. Substitution and diffusion operations, based on the matrix, facilitate fast conversion of plaintext and images into ciphertext and cipher images. The paper describes the encryption algorithm, discusses the simulation results and compares with results obtained from Advanced Encryption Standard (AES). It is shown that the proposed algorithm is capable of encrypting images eight times faster than AES.

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As the number of processors in distributed-memory multiprocessors grows, efficiently supporting a shared-memory programming model becomes difficult. We have designed the Protocol for Hierarchical Directories (PHD) to allow shared-memory support for systems containing massive numbers of processors. PHD eliminates bandwidth problems by using a scalable network, decreases hot-spots by not relying on a single point to distribute blocks, and uses a scalable amount of space for its directories. PHD provides a shared-memory model by synthesizing a global shared memory from the local memories of processors. PHD supports sequentially consistent read, write, and test- and-set operations. This thesis also introduces a method of describing locality for hierarchical protocols and employs this method in the derivation of an abstract model of the protocol behavior. An embedded model, based on the work of Johnson[ISCA19], describes the protocol behavior when mapped to a k-ary n-cube. The thesis uses these two models to study the average height in the hierarchy that operations reach, the longest path messages travel, the number of messages that operations generate, the inter-transaction issue time, and the protocol overhead for different locality parameters, degrees of multithreading, and machine sizes. We determine that multithreading is only useful for approximately two to four threads; any additional interleaving does not decrease the overall latency. For small machines and high locality applications, this limitation is due mainly to the length of the running threads. For large machines with medium to low locality, this limitation is due mainly to the protocol overhead being too large. Our study using the embedded model shows that in situations where the run length between references to shared memory is at least an order of magnitude longer than the time to process a single state transition in the protocol, applications exhibit good performance. If separate controllers for processing protocol requests are included, the protocol scales to 32k processor machines as long as the application exhibits hierarchical locality: at least 22% of the global references must be able to be satisfied locally; at most 35% of the global references are allowed to reach the top level of the hierarchy.

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Aquest projecte té com a objectius: determinar les Directrius a seguir per la futura redacció d’un protocol de gestió de les zones inundables del PNAE, amb la finalitat de potenciar la presència d’aus; determinar les millors condicions d’hàbitat per les poblacions d’aus del PNAE i redactar unes línies de seguiment que permetin d'una banda avaluar si les pautes proposades tindran l’efecte desitjat i d'altra banda que permetin la redacció del protocol de gestió

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El treball té l’objectiu de dissenyar un protocol d’actuació que contempli aspectes sobre prevenció, detecció i intervenció contra l’absentisme escolar i la desescolarització al municipi. Per a això s’ha desenvolupat una diagnosi municipal d’anàlisi de la realitat sobre el tema, fent èmfasi en la intervenció socioeducativa que s’ha de realitzar per a tractar el fenomen des d’una perspectiva holística i global

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La I Trobada de Coordinadors Ambientals tuvo lugar el día 10 de mayo de 2004 en el CEP de Palma y se organizó en colaboración con el Seminario de Ambientalización de centros escolares (SACE). El autor es profesor del colegio Sant Francesc d'Asís (Sa Pobla, Mallorca) y miembro de SACE

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Animation with key areas of consideration includes audio. This version has a scaleable player

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protocol writing Methodology for evidence-based practice