5,145 research outputs found

    Near-wall reconstruction of higher order moments and length scales using the POD

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    An analysis of the near-wall behavior of the proper orthogonal decomposition (POD) eigenfunctions derived from direct numerical simulation (DNS) of channel flow is performed. Consistent with previous studies, a low order multi-mode reconstruction of the kinetic energy and Reynolds shear stress suffices. A similar reconstruction of the isotropic dissipation rate is shown to be insufficient, however. An analysis is performed of the multi-mode composition of the dissipation rate in the near-wall region, and it is shown that a significant number of higher-order modes are required to achieve the correct asymptotic consistency in the near-wall region. In an attempt to avoid this problem, a length scale definition is proposed in terms of an integration of the correlation tensor which factors in the presence of the wall. The wall is accounted for by only integrating out to 2y(+) and not over the entire domain. Viscous and inviscid estimates for the dissipation were used in the near-wall and core regions respectively, in conjunction with this length scale representation to obtain an estimate of the dissipation throughout the domain. The resulting dissipation exhibits the proper behavior near the wall and in the inertial layer. A 1 POD mode estimate of the length scale is computed and found to agree quite well with the length scale obtained when the entire correlation tensor is used

    Thinking and Willing in Locke's Theory of Human Freedom

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    Locke a apporté des changements significatifs à plusieurs points de sa psychologie morale au fil des cinq premières editions de l'Essay. Je ferai valoir qu'en acceptant une certaine liberté de la volonté (willing) dans sa correspondance avec van Limborch (1702) et en concédant une certaine > dans la cinquième édition de l'Essay (1706), Locke ne comprometpas la cohérence de sa position définitive, contenue dans la cinquième édition, ces libertés étant distinctes du genre de libre arbitre qu'il rejette à maintes reprises. Je tenterai de souligner la continuité de la pensée de Locke sur la liberté humaine en faisant appel à sa théorie de la liberté de pensée, qui n'a cessé d'évoluer dés la première éditio

    Unheilige Bücher. Zur Implosion mythischen Erzählens in der ,Prosa Edda‘

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    The so called ‘Prose Edda' or ‘Snorra Edda', usually dated to the third decade of the 13th century, contains after a short prologue two substantial sections dealing mainly with mythography and poetics and a long concluding skaldic poem. In the extant medieval manuscripts from around 1300 and the beginning of the 14th century, additional material like genealogies, grammatical treatises, etc. is included. The present paper focuses on one of the earliest of these manuscripts, codex DG 11 4to, University Library Uppsala, and analyses some central features of the specific way in which it presents different narrative layers. For the first time, this analysis combines a study of textual and visual aspects of the manuscript, and special attention is given to two of the many illustrations in this codex. Together with later scribal notes, the drawings contribute heavily to the process of framing, which is one of the main features of the ‘Prose Edda'. This process of creating potentially endless narrative and visual frames is part of the text‘s ambition to establish a distance to the traditional pagan myths and to facilitate new fictional possibilitie

    Pre-Modern Nordic Memories in their Literary Contexts

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    The study of memory has become a central field in saga scholarship in recent years. The present article deals with a number of remarkable mnemonic phenomena in Old Norse-Icelandic narratives. It contextualizes them in biblical, classical, and more modern examples of memory culture. These serve as texts of reference for the Norse narratives that are in the focus of this article. Some of the analyses are inspired by the German philosopher Hans Blumenberg’s work on how myth has always already transgressed to memory (reception) and the art historian Aby Warburg’s concept of pathos formulae that produce emotional impacts and mnemonic tropes.Aspects that are treated are for instance acts of commemoration as social and cultural activities, eddic mytho-narratives as stories to remember, the importance of the body and the senses in terms of memory studies, the interrelationship of remembrance and oblivion, and finally pre-modern mediologies. Central texts discussed in the article are eddic poems such as Völuspá (The Seeress’s Prophecy), skaldic poetry and its mnemonic pictorality, Icelandic sagas and historical writings (Icelandic Book of Settlement), examples of folklore. Some outstanding features are stellar memories, the question whether the place of memory is in the human breast or brain, or the importance of avian imagery in narratives about birds as preeminent media of remembering and forgetting.The article has a comparative approach. It attempts to show how Old Norse-Icelandic literature is closely contextualized within a web of Scandinavian and non-Scandinavian narratives and thoroughly shaped by features of cultural memory, shifting constructions of and dealings with ever changing imaginations of pasts

    High-Rises and Urban Specificity: Politics of Vertical Construction in Paris, London, and Vienna

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    High-rise buildings have been experiencing a significant boom worldwide over the past two decades. This is true not least for European cities, where church steeples, town hall towers, and chimneys were the main vertical accents in city centers for a long time. This article focuses on the construction of high-rise buildings as a “glocal” phenomenon. The vertical building type has spread around the world, but approaches to it are site-specific and inextricably entangled with local problems, modes of action, and discourses. Construction strategies and discussions about tall buildings are quite diverse even in Europe alone. Presenting case studies of Paris, London, and Vienna, this article looks at three metropolises in which vertical building has caused particular unrest in recent years and reveals enlightening contrasts between them. In exploring the question of how distinctions are made in these cities between desirable and quasi-illegitimate buildings, or “possible” and “impossible” locations, I analyze city-specific patterns relating to vertical construction. Special attention is paid to urban planning—the activities of those actors who are responsible for developing strategies and implementing and concretizing legal regulations. The discussion draws on a larger research project and is based on the grounded theory research perspective. The data pool includes a large number of published and unpublished documents as well as interviews with actors from the fields of urban planning, architecture, and historic preservation. From a theoretical point of view, the article draws on reflections on the “specificity of cities” and “glocalization” in urban research

    Book review: the Infinite Desire for Growth by Daniel Cohen

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    In The Infinite Desire for Growth, Daniel Cohen offers a historical and philosophical account of the adoption of growth as a principle and goal in economic theory from the Enlightenment to the present day. While the essays at times overlook the specific historical and political contexts in which the concept of growth emerged and developed, the collection is thought-provoking and will contribute to contemporary debates around growth, finds Ryan Glauser

    The Design of a 24-bit Hardware Gaussian Noise Generator via the Box-Muller Method and its Error Analysis

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    In regards to data transmission in communication systems, there is need for robust emulation of communication channels via Gaussian noise generation. Over time, larger sample sizes are desired to reach farther into the tail ends of the distribution and faster sample generation speeds are desired versus the software implementations. This paper proposes a Gaussian noise generator utilizing the Box-Muller method written in Verilog HDL targeting a 65nm ASIC process utilizing Synopsys Design Compiler. The design creates two 24-bit noise samples per clock cycle and each sample is accurate to one unit in the last place. A sample can represent up to 9.42σ, which allows for a sample size of 2 · 1020. The design generates 800 million samples/s at a clock frequency of 400MHz. After a thorough error analysis, a bit-exact model was created in MATLAB and a thorough probability and statistic analysis was executed on the generated sample sets
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