10,614 research outputs found

    Report on the Second Workshop on Distributed AI

    Get PDF
    On June 24, 1981 twenty-five participants from organizations around the country gathered in MIT's Endicott House for the Second Annual Workshop on Distributed AI. The three-day workshop was designed as an informal meeting, centered mainly around brief research reports presented by each group, along with an invited talk. In keeping with the spirit of the meeting, this report was prepared as a distributed document, with each speaker contributing a summary of his remarks.MIT Artificial Intelligence Laborator

    Energy and performance-aware scheduling and shut-down models for efficient cloud-computing data centers.

    Get PDF
    This Doctoral Dissertation, presented as a set of research contributions, focuses on resource efficiency in data centers. This topic has been faced mainly by the development of several energy-efficiency, resource managing and scheduling policies, as well as the simulation tools required to test them in realistic cloud computing environments. Several models have been implemented in order to minimize energy consumption in Cloud Computing environments. Among them: a) Fifteen probabilistic and deterministic energy-policies which shut-down idle machines; b) Five energy-aware scheduling algorithms, including several genetic algorithm models; c) A Stackelberg game-based strategy which models the concurrency between opposite requirements of Cloud-Computing systems in order to dynamically apply the most optimal scheduling algorithms and energy-efficiency policies depending on the environment; and d) A productive analysis on the resource efficiency of several realistic cloud–computing environments. A novel simulation tool called SCORE, able to simulate several data-center sizes, machine heterogeneity, security levels, workload composition and patterns, scheduling strategies and energy-efficiency strategies, was developed in order to test these strategies in large-scale cloud-computing clusters. As results, more than fifty Key Performance Indicators (KPI) show that more than 20% of energy consumption can be reduced in realistic high-utilization environments when proper policies are employed.Esta Tesis Doctoral, que se presenta como compendio de artículos de investigación, se centra en la eficiencia en la utilización de los recursos en centros de datos de internet. Este problema ha sido abordado esencialmente desarrollando diferentes estrategias de eficiencia energética, gestión y distribución de recursos, así como todas las herramientas de simulación y análisis necesarias para su validación en entornos realistas de Cloud Computing. Numerosas estrategias han sido desarrolladas para minimizar el consumo energético en entornos de Cloud Computing. Entre ellos: 1. Quince políticas de eficiencia energética, tanto probabilísticas como deterministas, que apagan máquinas en estado de espera siempre que sea posible; 2. Cinco algoritmos de distribución de tareas que tienen en cuenta el consumo energético, incluyendo varios modelos de algoritmos genéticos; 3. Una estrategia basada en la teoría de juegos de Stackelberg que modela la competición entre diferentes partes de los centros de datos que tienen objetivos encontrados. Este modelo aplica dinámicamente las estrategias de distribución de tareas y las políticas de eficiencia energética dependiendo de las características del entorno; y 4. Un análisis productivo sobre la eficiencia en la utilización de recursos en numerosos escenarios de Cloud Computing. Una nueva herramienta de simulación llamada SCORE se ha desarrollado para analizar las estrategias antes mencionadas en clústers de Cloud Computing de grandes dimensiones. Los resultados obtenidos muestran que se puede conseguir un ahorro de energía superior al 20% en entornos realistas de alta utilización si se emplean las estrategias de eficiencia energética adecuadas. SCORE es open source y puede simular diferentes centros de datos con, entre otros muchos, los siguientes parámetros: Tamaño del centro de datos; heterogeneidad de los servidores; tipo, composición y patrones de carga de trabajo, estrategias de distribución de tareas y políticas de eficiencia energética, así como tres gestores de recursos centralizados: Monolítico, Two-level y Shared-state. Como resultados, esta herramienta de simulación arroja más de 50 Key Performance Indicators (KPI) de rendimiento general, de distribucin de tareas y de energía.Premio Extraordinario de Doctorado U

    The Future of Information Sciences : INFuture2011 : Information Sciences and e-Society

    Get PDF

    Mitochondrial DNA polymorphisms in Southern African populations.

    Get PDF
    A thesis submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy.The subject of this thesis is mitochondrial DNA (mtDNA) variation in southern African populations. The purpose of this study was twofold. Firstly, mtDNA variations were used to investigate the genetic affinities of Negroid, Khoisan, Caucasoid and "Coloured" populations in an attempt to refine theories on southern African population affinities and prehistory. MtDNA variations were detected using two different methods. The first method makes use of restriction fragment length polymorphisms (RFLPs) detected with the restriction enzymes Hpal, BamUI, Haell, Mspl, Avail and Hindi in 795 unrelated individuals from twenty ethnic groups within the Khoisan, Negroid, Caucasoid and "Coloured" populations from South Africa and Namibia. The combinations of the various restriction enzyme patterns (morphs) for the enzymes Hpal, Bam HI, Hae II, Mspl, Avail and Hindi (in this order), were used to derive the mtDNA type for each individual studied. This resulted in the discovery of 52 distinct mtDNA types: 30 of which had been previously reported, 28 out of 32 resulted from new combinations of enzyme morphs and 4/32 were due to the discovery of new enzyme morphs (MspI-17 in the Ashkenazi Jewish population and AvaII-31, AvaII-32 and AvaII-33 in the South African "Coloured" population). The second method involves sequencing approximately 750 base pairs of mtDNA contained within the two hypervariable segments within the non-coding control region of the mtDNA molecule in 144 individuals, most of whom where investigated for mtDNA RFLP variations. Pairwise comparisons of mtDNA sequences revealed 119 variant sites which gave rise to 129 unique mtDNA types.WHSLYP201

    Domain specific modeling and analysis

    Get PDF
    It is desirable to model software systems in such a way that analysis of the systems, and tool development for such analysis, is readily possible and feasible in the context of large scientific research projects. This thesis emphasizes the methodology that serves as a basis for such developments. I focus on methods for the design of data-languages and their corresponding tools.UBL - phd migration 201
    corecore