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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Caso de estudio de comunicaciones seguras sobre redes móviles ad hoc

Rocabado, Sergio 11 March 2014 (has links)
En este trabajo se presenta el estudio de un caso de integración de una MANET, desplegada en una zona remota, a una red de infraestructura. La finalidad principal es la de proporcionar, a los nodos de la red ad hoc, acceso “seguro” a un servidor de la red de infraestructura, sin comprometer recursos como ancho de banda y energía que son limitados en la zona de despliegue. Para ello, se implemento un escenario de pruebas que comprende el despliegue de una MANET en zona remota y la integración de la misma a una red de infraestructura a través de la red celular. Sobre el escenario propuesto se establecieron canales de comunicación extremo a extremo, entre un nodo de la MANET y un servidor de infraestructura. Inicialmente, se realizaron pruebas inyectando tráfico de datos sobre un canal “no seguro” para obtener valores de referencia para latencia, throughput y consumo de energía. Luego, se efectuaron las mismas pruebas utilizando canales de comunicación “seguros” configurados sobre protocolos IPSEC y SSL/TLS. Los resultados obtenidos utilizando canales “seguros” fueron comparados con los valores de referencia para determinar las diferencias de consumo de recursos. Las desviaciones que surgieron de estas comparaciones, permitieron: - Establecer el consumo adicional de recursos generado por el uso de protocolos seguros. - Realizar un estudio comparativo de rendimiento, entre diferentes configuraciones de protocolos de seguridad. - Determinar que protocolo seguro se adapta mejor a este tipo de entornos.
2

Molecular aspects of dormancy in peach (Prunus persica [L.] Batsch.)

Leida, Carmen Alice 25 May 2012 (has links)
Dormancy is one of the most important adaptive mechanisms developed by perennial plants, in order to survive the low temperatures of autumn and winter in temperate climates. The study of the genes regulated during dormancy release is crucial to understand the process, with the final objective of the development of new varieties with a better adaptation to certain environments; in particular in the Mediterranean area. The general aim of this work is to understand the molecular and physiological mechanisms underlying the maintenance and release of seasonal dormancy in peach. The first part of this work is focused on the identification of peach genes related to dormancy release by suppression subtractive hybridization (SSH) and microarray hybridization. A significant number of genes identified in this work were homologous to ABA and drought related genes from other species. Our data contribute to highlight a prominent role of ABA in dormancy processes and also uncover elements of the ABA and drought regulatory response in peach, as an ABA-INSENSITIVE5 (ABI5) binding protein (AFP)-like, a dehydration-responsive element (DRE)-binding protein (DREB2C)-like, a calcium-binding annexin, and several genes regulated by stress signalling pathways. Other identified genes were also evaluated to assess the chilling requirement of cultivars by analysis of expression showing a very good correlation between the expression pattern of DAM5, together with other transcripts (BD396, DB247, SB280 and PpB63) and the chilling requirements values of five different varieties ('Big Top', 'Catherina', 'Fergold', 'Maruja' and 'Springlady') measured following Utah and Dynamic models. Furthermore, a study of chromatin modifications associated to dormancy release in the DAM6 gene is presented. A ChIP analysis of DAM6 promoter and structural gene revealed chromatin modification events similar to those observed in vernalization of Arabidopsis and cereals. / Leida, CA. (2012). Molecular aspects of dormancy in peach (Prunus persica [L.] Batsch.) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/15864 / Palancia
3

Pardeamiento enzimático del fruto de níspero (Eriobotrya japonica cv. Algerie): enzimología y fisiología de las polifenol oxidasas

Sellés-Marchart, Susana 11 June 2007 (has links)
Ministerio de Ciencia y Tecnología y Fondos Europeos de Desarrollo Regional (FEDER), proyectos AGF99-0396, BIO-2002-03100 y BIO-2005-00332
4

Evaluation, Analysis and adaptation of web prefetching techniques in current web

Doménech i de Soria, Josep 06 May 2008 (has links)
Abstract This dissertation is focused on the study of the prefetching technique applied to the World Wide Web. This technique lies in processing (e.g., downloading) a Web request before the user actually makes it. By doing so, the waiting time perceived by the user can be reduced, which is the main goal of the Web prefetching techniques. The study of the state of the art about Web prefetching showed the heterogeneity that exists in its performance evaluation. This heterogeneity is mainly focused on four issues: i) there was no open framework to simulate and evaluate the already proposed prefetching techniques; ii) no uniform selection of the performance indexes to be maximized, or even their definition; iii) no comparative studies of prediction algorithms taking into account the costs and benefits of web prefetching at the same time; and iv) the evaluation of techniques under very different or few significant workloads. During the research work, we have contributed to homogenizing the evaluation of prefetching performance by developing an open simulation framework that reproduces in detail all the aspects that impact on prefetching performance. In addition, prefetching performance metrics have been analyzed in order to clarify their definition and detect the most meaningful from the user's point of view. We also proposed an evaluation methodology to consider the cost and the benefit of prefetching at the same time. Finally, the importance of using current workloads to evaluate prefetching techniques has been highlighted; otherwise wrong conclusions could be achieved. The potential benefits of each web prefetching architecture were analyzed, finding that collaborative predictors could reduce almost all the latency perceived by users. The first step to develop a collaborative predictor is to make predictions at the server, so this thesis is focused on an architecture with a server-located predictor. The environment conditions that can be found in the web are als / Doménech I De Soria, J. (2007). Evaluation, Analysis and adaptation of web prefetching techniques in current web [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1841 / Palancia
5

Circuitos embebidos aplicados a equipos médicos

Gómez Cornejo Campana, David Yusseff January 2011 (has links)
This thesis describes the design guidelines from two medical teams, electrocardiogram and pulse oximetry using embedded logic circuitry such as FPGA and microcontrollers, digital filters used to filter the signals obtained from analog converters to digital, graphic obtaining the data is displayed in a graphic display GLCD, and has an interface to send data to a PC through a port USB 2 at full speed. The digital filters used are FIR filters, these filters are chosen to be linear and time invariant, developed with 40 coefficients FIR filters, these filters were implemented in the FPGA, use a FPGA that has implemented only 20 multipliers For the implementation we used the VHDL language and algorithmic state machines in order to control the 20 boxes and get the 40 products. Filtered data in the stage of the FPGA, are taken to a microcontroller that is responsible for managing the data, can lead to a graphic display GLCD, and so we can see the signal and obtained values or you can send the data to a PC right through USB port and software right through it can see the graphics on the PC.
6

Control de la floración en el género prunus. Factores climáticos y nutricionales

González Rossia, Diego Esteban 06 May 2008 (has links)
Los Prunus tienen tendencia a cuajar muchos frutos, lo que reduce las posibilidades de obtener frutos con buen tamaño y calidad. Esta tesis doctoral describe una técnica agronómica basada en la aplicación de ácido giberélico (GA3), para reducir la floración y los costos de aclareo manual en cultivares de Prunus. También se estudian las implicaciones de los frutos y los inhibidores de la síntesis de giberelinas (Paclobutrazol, prohexadione-Ca) en el proceso de la floración. Complementariamente, se estudiaron los requerimientos de temperatura para la brotación y floración, y su dependencia de los contenidos en carbohidratos (CH). La aplicación de GA3 durante el período de inducción floral redujo la floración en unos 40%-50% en melocotones, nectarinas y ciruelos, siendo 50 mg 1-1 la dosis más adecuada de GA3. El tratamiento afectó la distribución de las flores a lo largo del ramo y algunos aspectos de la eficiencia del PSII. Se comprobó un efecto inhibidor del fruto sobre el proceso de floración, directamente mediante la reducción del número de yemas florales (YF), e indirectamente reduciendo el número de brotes en desarrollo. De ahí que se proponga la hipótesis de que la floración no es un proceso inductivo, sino más bien un proceso inhibitorio. Tanto el contenido de CH del floema de brotes y de raíces fibrosas, no ha podido relacionarse con el proceso de iniciación floral, aunque sí con los requerimientos energéticos para brotar. Sin embargo, se han encontrato evidencias de algunas perturbaciones en el proceso de reducción del ión nitrato en árboles con escasa tendencia a florecer. Los experimentos sobre varetas, demostraron que el frío promueve la brotación de yemas vegetativas (YV) y YF, siendo mayor el efecto sobre las primeras. Una gran acumulación de frío disminuye el porcentaje la brotación de las YF en cultivares con bajos requerimientos de frío disminuyendo el tiempò medio de brotación (MTB) de YV más rápidamente que el de YF. Se demuestra que existe una corr / González Rossia, DE. (2006). Control de la floración en el género prunus. Factores climáticos y nutricionales [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1827 / Palancia
7

Simulace SDN sítě / Simulation of SDN network

Vrablic, Pavol January 2017 (has links)
The main aim of this work is to become familiar with the technology of software-defined networks and learn to use some of the tools to measure and simulate these networks.
8

[en] PREFETCHING CONTENT IN MULTIMEDIA PRESENTATIONS / [pt] PRÉ-BUSCA DE CONTEÚDO EM APRESENTAÇÕES MULTIMÍDIA

AMPARITO ALEXANDRA MORALES FIGUEROA 16 March 2015 (has links)
[pt] Quando entregamos e apresentamos aplicações multimídia por meio de uma rede de comunicação, a latência de exibição pode representar um fator central e crítico que afeta a qualidade da apresentação multimídia. Na entrega de uma apresentação multimídia de boa qualidade o sincronismo é prevalecido, consequentemente, os conteúdos são exibidos de forma contínua, conforme as especificações do autor da aplicação. Nesta tese, um plano de pré-busca de conteúdos multimídia é proposto com o intuito de reduzir a latência de exibição e garantir o sincronismo entre os objetos de mídia que fazem parte da apresentação multimídia. O mecanismo proposto considera as aplicações multimídia desenvolvidas na linguagem declarativa NCL e utiliza a vantagem do sincronismo estar baseado em eventos, na determinação da ordem adequada de recuperação dos diferentes objetos de mídia e no cálculo dos seus tempos de início de recuperação. Aspectos importantes a serem considerados em um ambiente de pré-busca são levantados e os diferentes algoritmos que compõem o plano de pré-busca são desenvolvidos. / [en] When delivering and presenting multimedia applications through a communication network, the presentation lag could be a major and critical factor affecting the multimedia presentation quality. In a good quality presentation the synchronism is always preserved, hence all the contents are presented in a continue way according to the authoring specifications. In this dissertation, a multimedia content prefetching plan is proposed in order to minimize the presentation lag and guarantee the synchronism between the media objects, which constitute the multimedia application. The proposed mechanism regards the multimedia applications developed using the NCL declarative language and it uses the events based synchronism advantage to determinate the ideal retrieval order of the media objects and to calculate their start retrieval times. Furthermore, important issues to be considered in a prefetch ambient are raised and the different algorithms that belong to the prefetching plan are developed.
9

Efficient and Scalable Cache Coherence for Many-Core Chip Multiprocessors

Ros Bardisa, Alberto 24 September 2009 (has links)
La nueva tendencia para aumentar el rendimiento de los futuroscomputadores son los multiprocesadores en un solo chip (CMPs). Seespera que en un futuro cercano salgan al mercado CMPs con decenas deprocesadores. Hoy en d�a, la mejor manera de mantener la coherencia decache en estos sistemas es mediante los protocolos basados endirectorio. Sin embargo, estos protocolos tienen dos grandesproblemas: una gran sobrecarga de memoria y una alta latencia de losfallos de cache.Esta tesis se ha centrado en estos problemas claves para la eficienciay escalabilidad del CMP. En primer lugar, se ha presentado unaorganizaci�n de directorios escalable. En segundo lugar, se hanpropuesto los protocolos de coherencia directa, que evitan laindirecci�n al nodo home y, por tanto, reducen el tiempo de ejecuci�nde las aplicaciones. Por �ltimo, se ha desarrollado una pol�tica demapeo para caches compartidas pero f�sicamente distribuidas, quereduce la latencia de acceso y garantiza una distribuci�n uniforme delos datos con el fin de reducir su tasa de fallos. Esto se traducefinalmente en un menor tiempo de ejecuci�n para las aplicaciones. / Chip multiprocessors (CMPs) constitute the new trend for increasingthe performance of future computers. In the near future, chips withtens of cores will become more popular. Nowadays, directory-basedprotocols constitute the best alternative to keep cache coherence inlarge-scale systems. Nevertheless, directory-based protocols have twoimportant issues that prevent them from achieving better scalability:the directory memory overhead and the long cache miss latencies.This thesis focuses on these key issues. The first proposal is ascalable distributed directory organization that copes with the memoryoverhead of directory-based protocols. The second proposal presentsthe direct coherence protocols, which are aimed at avoiding theindirection problem of traditional directory-based protocols and,therefore, they improve applications' performance. Finally, a novelmapping policy for distributed caches is presented. This policyreduces the long access latency while lessening the number of off-chipaccesses, leading to improvements in applications' execution time.
10

Komprese videa v obvodu FPGA / Implementation of video compression into FPGA chip

Tomko, Jakub January 2014 (has links)
This thesis is focused on the compression algorithm's analysis of MJPEG format and its implementation in FPGA chip. Three additional video bitstream reduction methods have been evaluated for real-time low latency applications of MJPEG format. These methods are noise filtering, inter-frame encoding and lowering video's quality. Based on this analysis, a MJPEG codec has been designed for implementation into FPGA chip XC6SLX45, from Spartan-6 family.

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