934 resultados para Athenæum (London, England)


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Mobile Ad hoc Networks (MANETs) are self-organized, infrastructureless, decentralized wireless networks consist of a group of heterogeneous mobile devices. Due to the inherent characteristics of MANE -Ts, such as frequent change of topology, nodes mobility, resource scarcity, lack of central control, etc., makes QoS routing is the hardest task. QoS routing is the task of routing data packets from source to destination depending upon the QoS resource constraints, such as bandwidth, delay, packet loss rate, cost, etc. In this paper, we proposed a novel scheme of providing QoS routing in MANETs by using Emergent Intelligence (El). The El is a group intelligence, which is derived from the periodical interaction among a group of agents and nodes. We logically divide MANET into clusters by centrally located static agent, and in each cluster a mobile agent is deployed. The mobile agent interacts with the nodes, neighboring mobile agents and static agent for collection of QoS resource information, negotiations, finding secure and reliable nodes and finding an optimal QoS path from source to destination. Simulation and analytical results show that the effectiveness of the scheme. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.ore/licenscs/by-nc-nd/4.0/). Peer-review under responsibility of the Conference Program Chairs

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Cooperative relaying combined with selection exploits spatial diversity to significantly improve the performance of interference-constrained secondary users in an underlay cognitive radio network. We present a novel and optimal relay selection (RS) rule that minimizes the symbol error probability (SEP) of an average interference-constrained underlay secondary system that uses amplify-and-forward relays. A key point that the rule highlights for the first time is that, for the average interference constraint, the signal-to-interference-plus-noise-ratio (SINR) of the direct source-to-destination (SI)) link affects the choice of the optimal relay. Furthermore, as the SINR increases, the odds that no relay transmits increase. We also propose a simpler, more practical, and near-optimal variant of the optimal rule that requires just one bit of feedback about the state of the SD link to the relays. Compared to the SD-unaware ad hoc RS rules proposed in the literature, the proposed rules markedly reduce the SEP by up to two orders of magnitude.

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The functional source coding problem in which the receiver side information (Has-set) and demands (Want-set) include functions of source messages is studied using row-Latin rectangle. The source transmits encoded messages, called the functional source code, in order to satisfy the receiver's demands. We obtain a minimum length using the row-Latin rectangle. Next, we consider the case of transmission errors and provide a necessary and sufficient condition that a functional source code must satisfy so that the receiver can correctly decode the values of the functions in its Want-set.

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We propose a distributed sequential algorithm for quick detection of spectral holes in a Cognitive Radio set up. Two or more local nodes make decisions and inform the fusion centre (FC) over a reporting Multiple Access Channel (MAC), which then makes the final decision. The local nodes use energy detection and the FC uses mean detection in the presence of fading, heavy-tailed electromagnetic interference (EMI) and outliers. The statistics of the primary signal, channel gain and the EMI is not known. Different nonparametric sequential algorithms are compared to choose appropriate algorithms to be used at the local nodes and the Fe. Modification of a recently developed random walk test is selected for the local nodes for energy detection as well as at the fusion centre for mean detection. We show via simulations and analysis that the nonparametric distributed algorithm developed performs well in the presence of fading, EMI and outliers. The algorithm is iterative in nature making the computation and storage requirements minimal.

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Esta tese tem como questão central investigar de que forma as propostas de legados apresentadas pelos realizadores dos megaeventos esportivos brasileiros Jogos Pan-Americanos de 2007, Copa do Mundo de Futebol de 2014 e Jogos Olímpicos Rio 2016 respondem aos interesses das políticas públicas. Para tanto, os objetivos consistiram em: a) verificar na história recente de três megaeventos esportivos ações de boas práticas ligadas aos possíveis legados dos seguintes eventos: Copa Mundo/2010 África do Sul, Jogos Sul-Americanos/2010 Medellín/Colômbia e Jogos Olímpicos/2012 Londres / Inglaterra; b) verificar, diante dos legados do evento Jogos Pan-Americanos Rio-2007, como se instituíram as relações entre Governo Federal e o órgão de administração nacional do esporte olímpico brasileiro (COB) na definição das ações do evento; c) verificar em que medida se dão as relações entre o atual Governo Federal e os órgãos de administração nacional do esporte (CBF e COB), responsáveis pela organização da Copa do Mundo de Futebol de 2014 e pelos Jogos Olímpicos do Rio de Janeiro de 2016, no que tange aos possíveis legados a serem deixados pelos referidos eventos, se eles se aproximam ou se afastam dos encontrados nos Jogos Pan-Americanos Rio-2007. O procedimento metodológico utilizado neste estudo foi realizado em quatro fases: a) revisão bibliográfica sobre o tema; b) levantamento e análise de documentos referentes aos eventos estudados; c) realização de sete entrevistas semiestruturadas, que foram gravadas, transcritas e categorizadas; d) categorização e análise dos documentos e das entrevistas levando em consideração os objetivos propostos na pesquisa. Os resultados demonstraram que as ações de boas práticas ligadas aos possíveis legados dos megaeventos verificados na história recente se posicionam no campo dos legados tangíveis para os Jogos de 2010 e 2012 e intangíveis para a Copa do Mundo de 2010. Quanto à relação entre Governo Federal e COB nas tomadas de decisão, com base nos legados, do Pan de 2007, os dados mostram que o processo se baseou em um planejamento frágil, um modelo de governança inadequado e a assinatura tardia da matriz de responsabilidade do evento. Com relação ao desenvolvimento de legados dos eventos de 2014 e 2016, observamos que o de imagem é que aparece de maneira mais relevante na pesquisa. Finalmente, para responder à questão central da presente pesquisa, chegamos à demonstração de que a base das propostas de legados do Pan de 2007 pouco se aproxima dos interesses das políticas públicas. Já para a Copa do Mundo de 2014 e para os Jogos de 2016, as propostas de legados se direcionam para ações que, se bem-executadas, podem de forma direta ou indireta atender os interesses das políticas públicas.

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A 3D model of melt pool created by a moving arc type heat sources has been developed. The model solves the equations of turbulent fluid flow, heat transfer and electromagnetic field to demonstrate the flow behaviour phase-change in the pool. The coupled effects of buoyancy, capillary (Marangoni) and electromagnetic (Lorentz) forces are included within an unstructured finite volume mesh environment. The movement of the welding arc along the workpiece is accomplished via a moving co-ordinator system. Additionally a method enabling movement of the weld pool surface by fluid convection is presented whereby the mesh in the liquid region is allowed to move through a free surface. The surface grid lines move to restore equilibrium at the end of each computational time step and interior grid points then adjust following the solution of a Laplace equation.

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We consider the problem of finding the heat distribution and the shape of the liquid fraction during laser welding of a thick steel plate using the finite volume CFD package PHYSICA. Since the shape of the keyhole is not known in advance, the following two-step approach to handling this problem has been employed. In the first stage, we determine the geometry of the keyhole for the steady-state case and form an appropriate mesh that includes both the workpiece and the keyhole. In the second stage, we impose the boundary conditions by assigning temperature to the walls of the keyhole and find the heat distribution and the shape of the liquid fraction for a given welding speed and material properties. We construct a fairly accurate approximation of the keyhole as a sequence of include sliced cones. A formula for finding the initial radius of the keyhole is derived by determining the radius of the vaporisation isotherm for the line heat source. We report on the results of a series of computational experiments for various heat input values and welding velocities.

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In this paper, the continuous casting process for steel slab production is modelled using a mult-physics approach. For this purpose, a Finite Volume (FV) numerical model was constructed in 3D, with the following characteristics: Time dependent, turbulent fluid flow and heat transfer in the molten steel and flux regions, solidification of the skin layer, under prescribed heat loss boundary conditions, particle tracking simulation of argon bubbles injected with the metal into the mould, full coupling between bubbles and liquid through buoyancy and interfacial forces using a novel gas accumulation technique, and a full transient simulation of flux-metal interface behaviour under the influence of gravity and fluid inertial forces and bubble plume buoyancy. The unstructure mesh FV code PHYSICA developed at Greenwich was used for carry out the simulations with physical process data and properties supplied by IRSID SA.

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Giovanni Battista Montano (1534-1621), who was born in Milan and trained as a woodcarver, relocated permanently to Rome in the early 1570s where his interest in sculpting was replaced by intense study of the city’s antique monuments and ruins. Although Montano carried out several sculptural and architectural projects during his time in Rome, it is his surviving corpus of drawings that testifies to his passion of exploring ancient architecture through the medium of drawing. While Montano was not famous during his lifetime, a large body of his intriguing designs became celebrated and widely circulated after his death thanks to the 1624 publication of Montano’s designs by his loyal pupil, Giovanni Battista Soria. Montano’s lifelong work differs from virtually all of his predecessors and contemporaries in its “fantastical” and ornamental nature. This thesis explores Montano’s artistic training as it relates to his later interest in imaginatively reconstructing antique buildings, along with his disregard for archaeological or historical accuracy. The subject matter upon which Montano focused is discussed, along with his objective in creating a large corpus of half-historical, half-invented drawings. His drawing techniques are explored with specific reference to the largest group of extant Montano drawings, today housed in Sir John Soane’s Museum, London, England, and also in reference to three original Montano drawings in the Centre Canadien d’Architecture/Canadian Centre for Architecture, Montréal. Also explored is the legacy and impact of Montano’s drawings and the later publications of his designs on the works of Roman Baroque architects, specifically Borromini and Bernini. This thesis ultimately attempts to understand the impact of the intellectual and artistic environment surrounding Montano in late sixteenth and early seventeenth century Rome, his drawing techniques, his choice of subject matter, and the reception that his unique works received from contemporary artists and intellectuals, along with those of the following generation.

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