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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

Fully Parameterized Finite Element Model of a Grand Piano Soundboard for Sensitivity Analysis of the Dynamic Behavior

Mokdad, Fatma January 2013 (has links)
The main objective of this thesis is to understand the mechanics of a grand piano soundboard and to investigate the influence of several parameters on its modal and vibrational behaviors. Various analysis techniques are made possible by a development of a fully parameterized Finite Element model of the soundboard which allows the user to modify most geometric and material parameters. In addition, two crucial features, namely crowning and downbearing, are included in the model and their individual and combined effects are observed. This study also accounts for the influence of geometric nonlinearities due to downbearing. The piano soundboard includes a large number of unknown factors stemming from its construction process and the material properties of the wood. This thesis uses sensitivity techniques to investigate the influence of various factors on the variability of the modal outputs (i.e., natural frequencies and mode shapes). The different aspects of the model are described in details and various sensitivity methods are tested in this context.
2

A determinação categorial do fetichismo como processo de síntese na obra de Marx e linha de força do primeiro capítulo d’O capital / The categorical determination of fetishism as a process of synthesis in Marx’s work and as line of force of the first chapter of Capital

Rodrigues, Victor César Fernandes 07 March 2018 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2018-04-26T19:42:11Z No. of bitstreams: 1 victorcesarfernandesrodrigues.pdf: 2872555 bytes, checksum: c16260689489652a3c8339f48c2d1bc8 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-09-03T12:12:24Z (GMT) No. of bitstreams: 1 victorcesarfernandesrodrigues.pdf: 2872555 bytes, checksum: c16260689489652a3c8339f48c2d1bc8 (MD5) / Made available in DSpace on 2018-09-03T12:12:24Z (GMT). No. of bitstreams: 1 victorcesarfernandesrodrigues.pdf: 2872555 bytes, checksum: c16260689489652a3c8339f48c2d1bc8 (MD5) Previous issue date: 2018-03-07 / A presente dissertação consiste fundamentalmente em um esforço de apreensão da categoria marxiana do fetichismo da mercadoria. Para tanto, me utilizei de algumas obras de Marx situadas no período que vai de 1857 a 1858 e dos Grundrisse até 1873, na segunda edição revisada por Marx que trata da exposição do fetichismo da mercadoria e seu segredo na última seção do primeiro capítulo d’O capital, livro primeiro. Pretendeu-se demonstrar, por um aspecto, que já neste primeiro capítulo Marx trabalha meridianamente aspectos e problemas que são coroados nesta última seção. Por esta razão submeteremos uma análise que possa provar isto. Por outro aspecto, também pretende-se demonstrar que, em seu processo investigativo, dentro do período delimitado, Marx vai paulatinamente incorporando a temática do fetichismo como “linha de força” de sua análise até ser incorporada e exposta na última seção do referido capítulo. Este segundo aspecto diz respeito ao fato de que nos livros II, III e IV d’O capital, escritos nos idos de 1861-1865, a temática do fetichismo comparece expressivamente em algumas de suas análises. Obras como os Manuscritos de 1861-1863 e o chamado “Capítulo VI Inédito”, assim como a Contribuição à crítica da economia política de 1859, assistem um tratamento marxiano do problema antes dele ser exposto de fato em sua segunda edição d’O capital de 1873 com um título a parte. Dessa maneira, estes dois aspectos constituem a síntese teórica de nossa investigação ora exposta. O fundamento deste trabalho consiste, pois, em tecer uma crítica de caráter teórico a qualquer suposição acerca do tema do fetichismo que o tome tão somente a partir do primeiro capítulo do livro primeiro d’O capital. Dentre estas razões, ratifica-se o fato de que este tema propriamente constitui-se como um processo de síntese na obra O capital, cujo coroamento no primeiro capítulo do livro primeiro resulta de múltiplas análises anteriores, feitas por Marx no decurso de muitos anos de investigação. Assim, submete à crítica qualquer suposição que relegue o referido tema tão somente ao primeiro capítulo do livro primeiro d’O capital. Todavia, outro aspecto reveste o conteúdo desta dissertação, que é: este tema propriamente dito emergiu na tradição marxista mediante uma complicada conjunção de variáveis. Dentre as principais, pode-se mencionar a contribuição de obras como a de Lukács, História e consciência de classe, e a de Isaac Rubin, A teoria marxista do valor, ambas de 1923. Pretendeu-se demonstrar que tais obras refletem esta conjunção de variáveis, ao mesmo tempo em que aparecem no cenário da tradição oferecendo o tema do fetichismo como um dos componentes centrais da contribuição teórica de Marx. Pretende-se uma contribuição de rigor para análise do problema marxiano do fetichismo, no que tange a legitimação deste referido problema como decisivo de ser apreendido também pelos assistentes sociais. / This dissertation consists fundamentally of an effort to understand the marxian category of commodity fetishism. In order to do so, I’ve used some of Marx’s works situated in the 185758 period, the Grundrisse up to 1873, the second edition revised by Marx that deals with the commodity fetishism and its secret in the last section of the first chapter of Capital, book one. I intended to demonstrate that, in a way, in this first chapter Marx already works meridian aspects and problems which are crowned in the last section. For this reason we will submit an analysis that can prove our thesis. In another aspect, during his investigative process in the established period, Marx gradually incorporates the thematic of the fetishism as a “line of force” of his analysis until it’s fully incorporated and displayed in the last section of the referred chapter. This aspect refers to the fact that in books II, III and IV of Capital, written between 1861 and 1865, the fetishism theme appears expressively in some of Marx’s analyses. In works such as the Manuscripts from 1861-1863 and the so-called “Unpublished Chapter VI”, and also A Contribution to the Critique of Political Economy of 1859, we find a marxian treatment of the problem before it was actually exposed in the second edition of Capital in 1873 under a title of its own. These two aspects constitute the theoretical synthesis of our inquiry. Therefore, the foundation of this work consists in presenting a theoretical criticism to any assumptions concerning the subject of fetishism that only take into account the first chapter of Capital, book one. Due to these reasons, we can ratify the fact that this subject is developed through a process of synthesis in the Capital, and that the crowning in the first chapter of its first book is the result of many previous analyses done by Marx during many years of inquiry. Thus, any assumption that relegates this subject only to the first chapter of the first book of the Capital is susceptible to criticism. However, another aspect coats the content of this dissertation, and that is: that this subject emerged in the marxist tradition through a complicated conjunction of variables. Amongst the main ones we could mention the contributions provided by works such as Lukács’ History and Class Consciousness and Isaac Rubin’s Essays on Marx’s Theory of Value, both from 1923. Our aim was to demonstrate that such works reflect this conjunction of variables and that at the same time they appear in the scene of the tradition presenting the subject of fetishism as one of the central components of Marx’s theoretical contribution. Our contribution is an intended rigorous analysis of the marxian problem of fetishism, touching upon the legitimation of said problem as being decisive for social assistants to familiarize themselves with.
3

Efeito do coroamento com papel?o na supress?o de gram?neas e no crescimento de esp?cies arb?reas

GON?ALVES, Fernando Lima Aires 26 February 2016 (has links)
Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-05-04T18:50:24Z No. of bitstreams: 1 2016 - Fernando Lima Aires Gon?alves.pdf: 4917479 bytes, checksum: d7c7e6d879e9495bcc0db5d59f03c813 (MD5) / Made available in DSpace on 2017-05-04T18:50:24Z (GMT). No. of bitstreams: 1 2016 - Fernando Lima Aires Gon?alves.pdf: 4917479 bytes, checksum: d7c7e6d879e9495bcc0db5d59f03c813 (MD5) Previous issue date: 2016-02-26 / Three studies were conducted to evaluate the efficiency of seedling crowning using cardboard in reforestation with arboreal species of the Atlantic. The first study aimed to test the effect of the crowning with cardboard on the growth of Atlantic Forest species planted in a pasture area with dominance of Andropogon bicornis. The experimental design was randomized blocks with two treatments and 12 repetitions. Treatments consisted of crowning with cardboard or crowning with hoe applied to 11 tree species. We evaluated the growth of plants by measuring the height (H) and diameter of the collar height (DAC) at 6, 12 and 18 months after planting beyond survival rate. It was also carried out an assessment of the costs of each treatment. The results showed that the board did not interfere significantly in any forest species assessed. However, the survival rate was higher in the treatment crown of cardboard (80.7%) compared to the capping treatment with hoe (73.1%). In the economic aspect, the crowning with cardboard obtained material cost and labor up to 50% lower than the crowning with hoe. In the second study we evaluated the crowning efficiency with cardboard in the suppression of four species of grasses commonly found in forest areas in the Atlantic Forest. Four experiments were set up in places with dominant species A. bicornis, Urochloa decumbens, Urochloa umidicola and Panicum maximum. The experimental design was completely randomized with five replications. The treatments were the culmination of cardboard and without crowning. The cardboard efficiency was monitored by sampling the total biomass and the level of senescence of grasses in the area crowned. The cardboard was efficient in suppressing the four species of grasses evaluated, because after the evaluation period (100- 170 days) had hardly live plant material in the field of crowns. In the third study was rated as the crowning with cardboard influences the temperature and moisture in the surface layers in the soil. The experimental design was a randomized complete block design with four treatments and eight repetitions. The treatments were 1 - crown with cardboard (cardboard disposed directly on the braqui?ria); 2 - no crowning; 3 - with cardboard crown after crown with hoe (willing cardboard on the exposed soil); 4 - crowning with hoe. The moisture in the layers from 0 to 5 cm and 5 to 10 cm of soil, and the temperature in the layers 0 and 2,5 cm, 2.5 to 5 cm and 5 to 10 cm of the soil were monitored during periods 19 and subsequent 7 days, respectively, at a rain simulation 130 mm for 24 hours and natural rainfall of 133 mm for 13 days. The results indicated that treatment 1 (crowning with cardboard) decreased soil drying speed while maintaining higher water content in the crown area compared to the other treatments. Both capping treatments showed cardboard soil temperature in the region of the crown to 8.5?C lower than the capping treatment with cardboard. The set of results of the three studies demonstrate that the use of the capping technique with cardboard in reforestation deployment can significantly reduce operating costs after planting, either by reducing hand labor used in capping operations, as the lower need for seedlings for replanting. / Foram conduzidos tr?s estudos objetivando avaliar a efici?ncia do coroamento de mudas com papel?o em reflorestamentos com esp?cies arb?reas da Mata Atl?ntica. O primeiro estudo teve como objetivo testar o efeito do coroamento com papel?o sobre o crescimento de esp?cies da Mata Atl?ntica plantadas em uma ?rea de pastagem com domin?ncia de Andropogon bicornis. O delineamento experimental foi em blocos casualizados com dois tratamentos e 12 repeti??es. Os tratamentos consistiram de coroamento com papel?o ou coroamento com enxada aplicados a 11 esp?cies arb?reas. Avaliou-se o crescimento das plantas atrav?s da mensura??o da altura (H) e di?metro a altura do coleto (DAC) aos 6, 12 e 18 meses ap?s o plantio al?m da taxa de sobreviv?ncia. Tamb?m foi realizada uma avalia??o dos custos de cada tratamento. Os resultados encontrados mostraram que o papel?o n?o interferiu de maneira significativa em nenhuma esp?cie florestal avaliada. Entretanto, a taxa de sobreviv?ncia foi maior no tratamento de coroamento com papel?o (80,7%) comparado ao tratamento de coroamento com enxada (73,1%). No aspecto econ?mico, o coroamento com papel?o obteve custo de material e m?o de obra at? 50% inferior ao do coroamento com enxada. No segundo estudo avaliou-se a efici?ncia do coroamento com papel?o na supress?o de quatro esp?cies de gram?neas forrageiras comumente encontradas em ?reas de reflorestamento no bioma Mata Atl?ntica. Foram montados quatro experimentos em s?tios com domin?ncia das esp?cies A. bicornis, Urochloa decumbens, Urochloa umidicola e Panicum maximum. O delineamento experimental foi o inteiramente casualizado com cinco repeti??es. Os tratamentos foram o coroamento com papel?o e sem coroamento. A efici?ncia do papel?o foi monitorada atrav?s de coletas da biomassa total e do n?vel de senesc?ncia das gram?neas na ?rea coroada. O papel?o se mostrou eficiente na supress?o das quatro esp?cies de gram?neas avaliadas, pois ap?s o per?odo de avalia??o (100 a 170 dias) praticamente n?o havia material vegetal vivo na ?rea das coroas. No terceiro estudo foi avaliado como o coroamento com papel?o influencia na temperatura e umidade nas camadas superficiais no solo. O delineamento experimental foi o de blocos casualizados com quatro tratamentos e oito repeti??es. Os tratamentos foram 1 ? coroamento com papel?o (papel?o disposto diretamente sobre a braqui?ria); 2 ? sem coroamento; 3 ? coroamento com papel?o ap?s coroamento com enxada (papel?o disposto sobre o solo exposto); 4 ? coroamento com enxada. A umidade, nas camadas de 0 a 5 cm e 5 a 10 cm do solo, e a temperatura, nas camadas de 0 a 2,5 cm, 2,5 a 5 cm e 5 a 10 cm do solo, foram monitorados durante per?odos de 19 e 7 dias subsequentes, respectivamente, a uma simula??o de chuva de 130 mm durante 24 hs e a chuvas naturais de 133 mm durante 13 dias. Os resultados indicaram que o tratamento 1 (coroamento com papel?o) diminuiu a velocidade de ressecamento do solo, mantendo maior teor de ?gua na ?rea da coroa em compara??o aos demais tratamentos. Ambos os tratamentos de coroamento com papel?o apresentaram temperatura do solo na regi?o da coroa at? 8,5?C menor do que no tratamento de coroamento com papel?o. O conjunto de resultados dos tr?s estudos realizados demonstram que o uso da t?cnica de coroamento com papel?o na implanta??o de reflorestamentos pode reduzir significativamente os custos operacionais ap?s o plantio, tanto pela redu??o de m?o-de-obra empregada em opera??es de coroamento, quanto pela menor necessidade de replantio de mudas.
4

Konstrukční návrh zubové spojky pro aplikaci v kolejové dopravě / Design of the Gear Coupling for Railway Vehicle Application

Pelíšek, Vojtěch January 2021 (has links)
The aim of this work was to create a design of a gear coupling for railway vehicle application. The work presents a comprehensive view of this issue. First of all, a brief theoretical introduction to the issue is made. The practical part follows, where the design of the whole coupling and especially the newly designed solutions are described in detail. The strength analysis performed deal with the key components that are necessary to ensure safe operation. These analyses can be applied not only for this particular case, but also to gear couplings of different designs, because in principle these calculations do not differ much. In the last chapter, which deals with the dynamic model, all the theoretical assumptions are verified, especially the coupling movements and the applied loads. If the reader deals with the issue of gear couplings, not only in the railway industry, this work presents a comprehensive view of this component. The designed coupling and all performed simulations are really usable in operation.

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