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Distortional Lateral Torsional Buckling Analysis for Beams of Wide Flange Cross-sectionsHassan, Rusul January 2013 (has links)
Structural steel design standards recognize lateral torsional buckling as a failure mode governing the capacity of long span unsupported beams with wide flange cross-sections. Standard solutions start with the closed form solution of the Vlasov thin-walled beam theory for the case of a simply supported beam under uniform moments, and modify the solution to accommodate various moment distributions through moment gradient expressions. The Vlasov theory solution is based on the assumption that cross-sectional distortional effects have a negligible effect on the predicted elastic critical moment. The present study systematically examines the validity of the Vlasov assumption related to cross-section distortion through a parametric study.
A series of elastic shell finite element eigen-value buckling analyses is conducted on simply supported beams subject to uniform moments, linear moments and mid span point loads as well as cantilevers subject to top flange loading acting at the tip. Cross-sectional dimensions are selected to represent structural steel cross-section geometries used in practice. Particular attention is paid to model end connection details commonly used in practice involving moment connections with two pairs of stiffeners, simply supported ends with a pair of transverse stiffeners, simply supported ends with cleat angle details, and built in fixation at cantilever roots.
The critical moments obtained from the FEA are compared to those based on conventional critical moment equations in various Standards and published solutions. The effects of web slenderness, flange slenderness, web height to flange width ratio, and span to height ratios on the critical moment ratio are systematically quantified. For some combinations of section geometries and connection details, it is shown that present solutions derived from the Vlasov theory can overestimate the lateral torsional buckling resistance for beams.
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Distortional Static and Buckling Analysis of Wide Flange Steel BeamsPezeshky, Payam January 2017 (has links)
Existing design provisions in design standards and conventional analysis methods for structural steel members are based on the simplifying kinematic Vlasov assumption that neglects cross-sectional distortional effects. While the non-distortional assumption can lead to reasonable predictions of beam static response and buckling strength in common situations, past work has shown the inadequacy of such assumption in a number of situations where it may lead to over-predicting the strength of the members. The present study thus develops a series of generalized theories/solutions for the static analysis and buckling analysis of steel members with wide flange cross-sections that capture distortional effects of the web. Rather than adopting the classical Vlasov assumption that postulates the cross-section to move and rotate in its own plane as a rigid disk, the present theories assume the web to be flexible in the plane of the cross-section and thus able to bend laterally, while both flanges to move as rigid plates within the plane of the cross-section to be treated as Euler-Bernouilli beams. The theories capture shear deformation effects in the web, as well as local and global warping effects.
Based on the principle of minimum potential energy, a distortional theory is developed for the static analysis of wide flange steel beams with mono-symmetric cross-sections. The theory leads to two systems of differential equations of equilibrium. The first system consists of three coupled equilibrium differential equations that characterize the longitudinal-transverse response of the beam and the second system involves four coupled equilibrium differential equations of equilibrium and characterizes the lateral-torsional response of the beam. Closed form solutions are developed for both systems for general loading. Based on the kinematics of the new theory, two distortional finite elements are then developed. In the first element, linear and cubic Hermitian polynomials are employed to interpolate displacement fields while in the second element, the closed-form solutions developed are adopted to formulate special shape functions. For longitudinal-transverse response the elements consist of two nodes with four degree of freedom per node for longitudinal-transverse response and for lateral-torsional response, the elements consist of two nodes with eight degrees of freedom per node. The solution is able to predict the distortional deformation and stresses in a manner similar to shell solutions while keeping the modeling and computational effort to a minimum.
Applications of the new beam theory include (1) providing new insights on the response of steel beams under torsion whereby the top and bottom flanges may exhibit different angles of twist, (2) capturing the response of steel beams with a single restrained flange as may be the case when a concrete slab provides lateral and/or torsional restraint to the top flange of a steel beam, and (3) modelling the beneficial effect of transverse stiffeners in reducing distortional effects in the web.
The second part of the study develops a unified lateral torsional buckling finite element formulation for the analysis of beams with wide flange doubly symmetric cross-sections. The solution captures several non-conventional features. These include the softening effect due to web distortion, the stiffening effect induced by pre-buckling deformations, the pre-buckling nonlinear interaction between strong axis moments and axial forces, the contribution of pre-buckling shear deformation effects within the plane of the web, the destabilizing effects due to transverse loads being offset from the shear centre, and the presence of transverse stiffeners on web distortion. Within the framework of the present theory, it is possible to evoke or suppress any combination of the features and thus isolate the individual contribution of each effect or quantify the combined contributions of multiple effects on the member lateral torsional capacity. The new solution is then applied to investigate the influence of the ratios of beam span-to-depth, flange width-to-thickness, web height-to-thickness, and flange width-to-web height on the lateral torsional buckling strength of simply supported beams and cantilevers. Comparisons with conventional lateral torsional buckling solutions that omit distortional and pre-buckling effects quantify the influence of distortional and/or pre-buckling deformation effects. The theory is also used to investigate the influence of P-delta effects of beam-columns subjected to transverse and axial forces on their lateral torsional buckling resistance. The theory is used to investigate the load height effect relative to the shear centre. Comparisons are made with load height effects as predicted by non-distortional buckling theories. The solution is adopted to quantify the beneficial effect of transverse stiffeners in controlling/suppressing web distortion in beams and increasing their buckling resistance.
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Anatomie de l'outrance : une esthétique du débordement dans le cinéma espagnol de la démocratie / Anatomy of Excess : an Aesthetic of the Extreme in the Spanish Cinema of DemocracyBracco, Diane 26 June 2015 (has links)
Un certain nombre de films réalisés après la mort du dictateur Franco et l’entrée de l’Espagne dans la postmodernité témoignent d’une indéniable prédilection de certains cinéastes espagnols pour l’excès et le débordement. Des noms tels que Pedro Almodóvar, Bigas Luna, Álex de la Iglesia, Santiago Segura ou Juanma Bajo Ulloa, entre autres, s’imposent à l’esprit lorsqu’on s’interroge sur l’impression d’outrance qui émane d’une partie de la production cinématographique de la démocratie. Le présent travail a pour ambition d’explorer les mécanismes et les enjeux de l’outrance, à travers un corpus réunissant plusieurs longs-métrages de ces cinq réalisateurs. Pierre angulaire d’un cinéma qui déforme et dissout toutes les frontières, cette notion, à première vue difficile à saisir, sera envisagée comme véritable concept esthétique, fondé sur les principes du franchissement et de la distorsion. C’est en particulier autour du corps, constamment manipulé, déformé, voire disséqué, qu’elle se polarise : aux épanchements des organismes de chair et aux débordements du corps social dans les différents univers fictionnels, répondent, chez chaque cinéaste, les migrations et réélaborations textuelles qui se jouent au sein du corps filmique. Ces opérations de métamorphose référentielle relèvent d’un processus de recyclage éminemment postmoderne, qui suppose l’hybridation de matériaux provenant tout autant de la tradition espagnole que de la culture mondialisée contemporaine. Voie d’expression d’une « espagnolité » soumise aux logiques transformatrices de la postmodernité, l’outrance apparaît comme une esthétique qui tend définitivement à brouiller les frontières, à tel point qu’elle finit même par franchir celles du film pour contaminer la périphérie extracinématographique. / Several films produced after the death of the dictator Franco and Spain’s entry into postmodernity show an undeniable penchant among some Spanish film-makers for excess and the extreme. Names like Pedro Almodóvar, Bigas Luna, Álex de la Iglesia, Santiago Segura and Juanma Bajo Ulloa, among others, spring to mind when we wonder about the impression of excess that emanates from part of the cinematographical production of democracy. This work aims to explore the mechanisms and stakes of excess through a collection of full-length films by these five directors. It will contemplate this notion, the keystone of a cinema that deforms and dissolves all limits which at first is elusive, based on the principles of distortion and the extreme. Because it is constantly manipulated, deformed, and even dissected, the body occupies a central8place in the aesthetic of excess: the textual migrations and re-elaborations that take place within the filmic body respond to both the outpourings of the bodies of flesh and blood and the excesses of the social body in the different fictional universes. These operations of referential metamorphosis pertain to an eminently postmodern process of recycling, which involves the hybridisation of materials that come from Spanish tradition, on the one hand, with those from contemporary globalised culture on the other. Means of expression of a “Spanishness” that is subjected to the logical transformations of postmodernity, excess constitutes an aesthetic that tends to blur limits, to such a point that it crosses the boundaries of the film to contaminate the extra-cinematographical periphery
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Automatic acoustic tests of conference phonesKirchmann, Carl Christian January 2017 (has links)
This master thesis was completed at Limes Audio in Umeå. Limes Audio are specialized in speech enhancement software which is mostly used in conference phones. Their software is used to reduce noise, echo cancellation as well as reduction of distortion. When a conference phone is malfunctioning it can be troublesome to find the cause of the problem. Common issues that lead to perceived poor audio quality are rattling plastics, loose parts and an environment with demanding acoustics. There is a need for automatic tests to run on conference phone which can diagnose audio quality and the acoustics of the environment where the conference phone is located in. A previous master thesis by Wilhelmsson called "Estimating Loudspeaker Distortion and Room Reverberation Time Using a Speakerphone" focused on evaluating several tests run in MATLAB for analyzing acoustic characteristics of a room. The goal of this thesis was to continue the work of the master thesis by Wilhelmsson. Previous tests served as a basis for this thesis. The tests where modified and rewritten in C and run on a Linux computer connected to a specific conference phone model. In the extended test made in this thesis using sine sweep signals, the reverberation time as well as the distortion for the conference phone setup was determined. The calculated reverberation time was compared to the results using Room EQ Wizard and gave almost identical results. Total harmonic distortion was not easy to relate to the perceived audio quality. There is a need to further develop methods to take into account other types of distortion than the total harmonic distortion. Rub & buzz is one kind of distortion that could be of interest. To investigate pass or fail thresholds for reverberation time as well as distortion is central for further development of this test software.
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Análise da distorção harmônica de um parque eólico através da sua modelagem no domínio do tempo e da frequênciaSchwanz, Daphne January 2013 (has links)
Neste trabalho será apresentado um estudo de caso sobre o cálculo da distorção harmônica gerada por um parque eólico através da sua modelagem nos domínios do tempo e da frequência. Será analisada a propagação das frequências harmônicas na rede básica e a influência da modelagem das linhas de transmissão nos resultados de distorção harmônica. Para este estudo serão utilizados os programas EMTP (ElectroMagnetic Transient Program) e HarmZs para as simulações no domínio do tempo e da frequência, respectivamente. Os parques eólicos simulados utilizam geradores do tipo multipolar síncrono, e para a sua conexão à rede elétrica um conversor de frequência. Os resultados obtidos com o programa EMTP serão comparados para validação com os dados obtidos através da simulação no domínio da frequência utilizando o programa de simulação HarmZ. Já a análise da propagação das frequências harmônicas será simulada somente no domínio do tempo. Assim, através dos resultados obtidos será possível comparar os programas de simulação, determinar os níveis de distorção harmônica em diversos pontos do sistema elétrico e a influência dos modelos utilizados. / This work will present a case study on the calculation of the harmonic distortion generated by a wind farm. Time and frequency domain simulations will be performed. Harmonic propagation will be analyzed. Furthermore, the influence of transmission lines and underground cables models will be verified when there are several frequencies present in the system. Softwares EMTP (ElectroMagnetic Transient Program) and HarmZs will be used for the simulations in the time and frequency domain, respectively. The simulated wind farm use multipolar synchronous generators and their connection to the grid is made through a frequency converter. The results obtained with EMTP will be compared for validation with the results obtained with HarmZs. Thus, by the obtained results it will be possible to compare simulation programs and to determine the levels of harmonic distortion at several points of the electrical system.
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Soldagem a arco elétrico com proteção gasosa em juntas de chapas finas de aço / Gas metal arc welding of thin sheet steelsAdnauer Tarquínio Daltro 01 June 2000 (has links)
O uso de chapas finas de aço, revestidas ou não, tem sido crescente nos últimos anos, principalmente aquelas que tem revestimento à base de zinco. Isto ocorre tanto na indústria automobilística e mecânica como na construção civil, que geralmente fabricam suas peças e estruturas utilizando um procedimento de soldagem. O objetivo deste trabalho é estabelecer procedimentos de soldagem à arco elétrico com proteção gasosa - GMAW - com transferência por curto circuito, para elementos de chapa fina de aço carbono não revestido e aço zincado, de modo a se obter junções de qualidade aceitável e diminuição das distorções decorrentes dos ciclos térmicos presentes durante a soldagem e, consequentemente a redução das tensões residuais. Em termos de qualidade da solda, propões-se uma combinação de consumíveis disponíveis no mercado, de modo a reduzir os defeitos como: porosidade, respingos, trincas e perda de revestimento. No caso das chapas finas de aço zincado, a melhor combinação de consumíveis encontrada foi: arame com baixo teor de desoxidantes, ER70S-3, e como gás de proteção a mistura 8% CO2 + 92% Ar. Quanto à redução e controle das distorções, três técnicas são utilizadas. A técnica que utiliza em escoadouro dinâmico de calor, formado por um jato de gás refrigerador aplicado logo após o arco de solda durante a soldagem, apresentou maior eficiência na redução das distorções, provenientes do ciclo térmico. / The thin sheet steels, coated or not, has been widely used nowadays, mainly the hot dip galvanized steel sheets. It\'s observed as in the mechanic and automobilist industry as in the civil construction that in manufacturing of pieces and structures employ welding procedures. The aim of this work is to establish procedures to gas metal are welding with short circuit transfer of thin sheet steel elements, not coated and zinc-coated steel, in order to get junctions of acceptance quality and reduction of welding stress and distortion. This distortion arise of the thermal cycles that occur during the welding. In terms of the weld quality is defined the best consumables combination available in the market, in such a way to reduce the weld defects like porosities, spatters, cracks and loss of covering. To galvanized steel sheets, the combination: wire ER70S-3 and mixture 8%CO2 + 92% Ar showed the best performance. Three techniques were employed for control and reduce the welding distortion. One that using a spot heat sink following the arc, in this case the cooling jet, was more efficient that others techniques.
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Imunidade tributária dos templos e o fenômeno da mercantilização das religiõesNaspolini, Ludmila Indalencio January 2018 (has links)
O objetivo do presente estudo é analisar a imunidade dos templos de qualquer culto. Por intermédio do exame dos conceitos que compõem a normativa e dos parâmetros objetivos que lhe conferem limites, pretende-se fixar a extensão da prerrogativa assegurada no artigo 150 da Constituição Federal. Delimitado este substrato teórico, o trabalho propõe-se a refletir acerca da interpretação da imunidade religiosa diante do atual contexto fático das religiões brasileiras, buscando expor releituras aptas a fornecer respostas mais satisfatórias ao desvirtuamento da prerrogativa observado na prática. / The aim of this study is to analyse the tax immunity of religious temples. The concepts that compose the normative and the parameters objectives that allow its limits were analysed, in order to fix the extension of the privilege granted by the art. 150 of the Constitution of Federative Republic of Brazil. This theoretical study aims to reflect about the interpretation of religious tax immunity toward the current context of brazilian religions, trying to expose reviews of the current method to grant more satisfactory responses for the distortion of the benefit that is shown in practice
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The effects of distortion : Investigating how different types of distortion affect timbral attributes and subjective preferenceWaldton Lézin, André January 2020 (has links)
The effects of distortion has been investigated prior to this study, however most of these studies focus on the objective physicalities of a certain type of distortion or they might apply distortion in static amounts to examine effects of loudspeaker distortion. Objectively the varying types of distortion may be different, however there are little explanations on how these types subjectively might sound different. This study aimed to investigate how subjective preference and perception of the timbral attributes warmth and roughness may vary between types of distortion, and if there was a pattern between these using three different types of distortion (zero-crossing, solid state and tube), applied at two different levels (high and low) and to two different instruments (guitar and vocals). The outcome indicated that subjects most prefer tube distortion and that this distortion was considered to provide the most amounts of warmth while also the least amounts of roughness. There were also interaction effects indicating guitar being less sensitive about the level of distortion while being more sensitive about the type of distortion for the measures of preference and amounts of roughness, when compared to vocals.
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Word Reordering for Statistical Machine Translation via Modeling Structural Differences between Languages / 統計的機械翻訳のための言語構造の違いのモデル化による語順推定Goto, Isao 23 May 2014 (has links)
2015-05-27に本文を差替 / 京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第18481号 / 情博第532号 / 新制||情||94(附属図書館) / 31359 / 京都大学大学院情報学研究科知能情報学専攻 / (主査)教授 黒橋 禎夫, 教授 田中 克己, 教授 河原 達也 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM
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Výkonový zesilovač a jeho linearizace pomocí lokálních zpětných vazeb / Power amplifier and its linearization using local feedbacksJanic, Lukáš January 2018 (has links)
The thesis deals with the construction of a linear power amplifier. Theoretical analysis of the final work explains the function of the amplifier blocks, which is necessary to understand the functions of the whole construction. Thesis continues in simulation analysis of separate blocks or whole construction and at the end of the implementation of the complete power amplifier.
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