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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.
221

Alternative plate deformation phenomenon for squeeze film levitation

Almurshedi, Ahmed January 2018 (has links)
This thesis deals with a theoretical and an experimental exploration of squeeze film levitation (SFL) of light objects. The investigations aimed to find the important design parameters controlling this levitation mechanism and also to suggest an alternative way to implement SFL. The study, through computer modelling and experimental validation, focused on Poisson's contraction effect for generating SFL. A finite element model (ANSYS) was verified by experimental testing of five different plate designs. Each plate was subjected to a uniaxial plain stress by an arrangement of two hard piezoelectric actuators (PZT) bonded to the bottom of the plate and driven with DC or AC voltages. It was observed that pulsation of a dimple or crest shaped elastic deformation along the longitudinal axis in the central area of the plate was created because of Poisson's contraction. This Poisson's effect generated the squeeze-film between the plate and the levitated object. The separation distance between a floating lightweight object and the plate was analysed using computational fluid dynamics (ANSYS CFX) through creation of a modelling model for the air-film entrapped between the two interacting surfaces - a typical three-dimensional fluid-solid interaction system (FSI). Additionally, the levitation distance has been experimentally measured by a Laser Sensor. A satisfactory agreement has been found between model predictions and experimental results. Two levitation systems, one based on a horn transducer (Langevin type) and the other one in the form of a plain rectangular plate made of Aluminium and firmly fastened at both ends with a surface-mounted piezoelectric actuator, were compared in this thesis. Both devices were based on SFL mechanism. Evidently, the performances of both designs were greatly influenced by the design structure and in particular by the driving plate characteristics such as plate size and geometry as well as the driving boundary conditions. To this end, physical experiments were carried out and it was found that the device utilising horn-type transducer yields better levitation performance. Ultimately, the research explained the confusion between three approaches to non-contact levitation through literature review and also pointed out some essential parameters like piezoelectric actuators location, material of the driving structure, coupled-field between the actuators and the driving structure and the fluid-solid interface that was existed between the excited plate and the levitated object.
222

Blockbuster vs. scattershot : a contingent relationship between product line length strategy and performance in the fast-moving consumer goods industry

Marinho Dias Torres Neto, Antonio January 2014 (has links)
Some firms focus on few products with broad appeal, whereas others leverage variety as an important part of their offering. This study investigates the conditions under which each of these product line length strategies is optimal in the fast-moving consumer goods industry. It does so by focusing on the relationship between product line length strategy and firm top-line performance, in the light of a discrete framework derived from the strategic fit paradigm and the strategic triangle. Results show that customer factors (i.e., variety per household and value per purchase) and competitor factors (i.e., concentration and proliferation) drive the strategic fit of a firm's product line length strategy to the market in which it competes, so that firms deploying market-fitting strategies face higher odds of market share growth than firms deploying contrarian strategies. Firms with certain company factors (i.e., innovativeness and brand equity), however, face higher odds of market share growth by challenging the market fit and deploying contrarian strategies than by deploying market-fitting strategies. This study offers a stepping stone towards addressing product line length strategy as a discrete choice on product line positioning, an innovative approach with potential to generate concrete business impact.
223

Simulação numérica do escoamento turbulento em motores de combustão interna

Zancanaro Junior, Flavio Vanderlei January 2010 (has links)
Com os grandes avanços ocorridos na disponibilização de computadores, existe uma tendência contínua para a utilização de técnicas computacionais auxiliando no projeto de equipamentos de engenharia. Cada vez mais estão se obtendo resultados bastante próximos às condições reais, incluindo a simulação de motores de combustão interna. Neste sentido o presente trabalho tem o objetivo de analisar o escoamento turbulento no processo de admissão de ar em um motor operando em ciclo Diesel. A investigação é focada na determinação da influência do passo de tempo no cálculo do coeficiente de descarga e razão de swirl. Adicionalmente, o campo de velocidades, pressão, energia cinética turbulenta e outros parâmetros são apresentados e analisados, com o objetivo de auxiliar no entendimento da dinâmica envolvida. Essencialmente, dois modelos de turbulência são empregados, juntamente com dois tratamentos de parede. Seus resultados também são confrontados e discutidos. A geometria considerada é de um motor Fiat 1.9 L quatro tempos com duas válvulas. A análise é concentrada em um único cilindro. O pacote computacional utilizado é o Star-cd, e seu aplicativo es-ice. A independência de malha foi obtida, chegando a 1.672.056 volumes. Os resultados são apresentados de duas formas. A primeira delas refere-se a resultados de simulações em regime permanente, realizadas em boa parte por outros autores, com ênfase na determinação do coeficiente de descarga e razão de swirl, estes confrontados com valores experimentais, visando à validação da metodologia. Fica evidente a importância da escolha do modelo de turbulência na simulação de motores de combustão interna, assim como das funções de interpolação utilizadas. Na segunda parte os resultados referem-se a uma análise transiente, considerando o movimento do pistão e válvulas, a 1500 RPM. Observa-se a grande exigência quanto ao passo de tempo requerido no transiente real, ficando demonstrado que para esta velocidade o menor passo de tempo utilizado, 0,05° (5.5555E-6 s), ainda é insuficiente para alguns momentos do ciclo. É possível notar maior influência no coeficiente de descarga do que na razão de swirl, em relação aos passos de tempo utilizados. A forte dependência do modelo de turbulência nos resultados obtidos é mais uma vez confirmada, conforme o esperado, já que as hipóteses sobre a física do fenômeno são diferentes em cada modelo. Os resultados quanto ao tratamento na parede não apresentaram significantes diferenças, quando aplicados junto ao modelo de turbulência k-ω SST. / Considering the increase in the availability of computers, there is a continuing trend toward the use of computational simulation aiding in the design of engineering equipments. Reasonable results, close to the real conditions, are obtained, including the simulation of internal combustion engines. In this way, the present work has the objective of analyzing the turbulent flow in the air intake process of an engine operating in Diesel cycle. The investigation focuses on the determination of the time step in the calculation of the air discharge coefficient and swirl ratio. Additionally, the turbulent kinetic energy, pressure and velocity fields, besides other parameters, are presented and analyzed, with the objective of aiding in the understanding of the involved dynamics. Essentially, two turbulence models are employed, together with two wall treatments. Their results are also confronted and discussed. The considered geometry is a four-stroke, 1.9-L FIAT engine, with two valves. The analysis is concentrated on a single cylinder. The software package used is the Star-cd, and its application es-ice. The mesh independence is carried out, arriving in 1.672.056 volumes. The results are presented in two ways. The first one refers to simulation results of the steady state, also accomplished by other authors, with emphasis in the determination of the discharge coefficient and swirl ratio. These data are confronted with experimental values, aiming to validate the applied methodology. The importance of the choice of the turbulent model becomes evident in the simulation of internal combustion engines, as well as the interpolation functions used. In the second part the results refer to a transient analysis, considering the valves and piston movement, at 1500 rpm. It is observed the great demand on time step required is observed for the real transient, demonstrating that, for this speed, the smallest time step used, 0.05º (5.5555E-6 s), is still insufficient for some moments of the cycle. Also regarding the time step, it is possible to notice a greater influence in the discharge coefficient than in the swirl ratio. The strong dependence of the turbulence model on the results is once again confirmed, as expected, since the hypotheses about the physics of the phenomenon are different in each model. The results, regarding the wall treatment, presented no significant differences, when applied together with the SST k-ω turbulence model.
224

A crítica cinematográfica na internet / Film criticism on the internet

Cruz, Álvaro André Zeini, 1988- 24 September 2018 (has links)
Orientador: Fernão Vitor Pessoa de Almeida Ramos / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-09-24T18:07:34Z (GMT). No. of bitstreams: 1 ZeiniCruz_AlvaroAndre_M.pdf: 2294717 bytes, checksum: 8fb4a484e3a886442377d6a8a1d3edfe (MD5) Previous issue date: 2013 / Resumo: Este trabalho propõe uma análise sobre a vertente da crítica cinematográfica brasileira que encontrou na internet um espaço propício para seu desenvolvimento. Visa elencar, compreender e distinguir características desta crítica através da historicização e reflexão de expoentes relevantes na esfera da crítica de cinema online. Assim, serão abordadas as revistas virtuais Contracampo, Cinética, Filmes Polvo, Interlúdio, Foco, RUA e os sites Cinequanon, Cinema em Cena, Críticos.com, Omelete e Adoro Cinema. O estudo ainda aborda a transformação da cinefilia usando como meio a internet e seus desdobramentos, como os blogues voltados ao cinema como temática / Abstract: This work proposes an analysis of the Brazilian branch of film criticism, which found a conducive space to development on the internet. It aims to list, understand and distinguish characteristics of this criticism by historicizing and reflecting on relevant exponents in the realm of film criticism online. Thus, we shall discuss the webzines Contracampo, Cinética, Filmes Polvo, Interlúdio, Foco, RUA, and the sites Cinequanon, Cinema em Cena, Críticos.com, Omelete and Adoro Cinema. The study also discusses the transformation of cinephilia using the internet as a medium and its consequences, such as blogs that focus the cinema as a theme / Mestrado / Multimeios / Mestre em Multimeios
225

Anna dos 6 aos 18 anos /

Gallep, Larissa Tannus. January 2012 (has links)
Orientador: José Leonardo do Nascimento / Banca: Omar Khoury / Banca: Simonetta Persichetti / Resumo: Com esta pesquisa a minha intenção foi a de realizar uma investigação do filme/documentário russo Anna dos 6 aos 18 e como ele expõe os momentos históricos do fim dos anos 1980 e começo dos 1990, com a queda da União Soviética e o surgimento da Perestroika. Tentei aqui apresentar uma análise de como esta obra, enquanto objeto de arte e documento histórico, se relaciona com as transformações e o discurso oficial do final da URSS. Foram analisadas as diferentes formas de articulação entre os elementos verbais e sonoros, mas com foco nos elementos estético-visuais (signos, ícones, sinais, movimentos de câmera, composições cênicas) e principalmente a montagem. O trabalho aqui aprestado é um estudo sobre o papel da montagem, do filme documentário enquanto documento histórico e do papel do diretor enquanto ―escultor do tempo‖. Para a realização deste trabalho foram realizadas entrevistas com profissionais desta área, bem como pesquisa e observação de diferentes obras cinematográficas e de artes plásticas que abordam a montagem. Também realizo a minha análise sobre algumas imagens escolhidas pelo diretor Nikita Mikhalkov que contam uma visão sobre este período da história russa vivenciada por ele juntamente com o crescimento de sua filha Anna, a heroína do filme objeto do nosso estudo / Abstract: With this research the intention was to investigate the russian documentary film called Anna from 6 to 18 and how he exposes historic moments in the late 1980s and beggining of 1990s among the Soviet Union fall and the emergence of Perestroyka. We try to present how this work, as art object and historic document, relates itself with the changes and the official version about the end of URSS. We analyzed the different forms of articulation between the verbal elements and sound, but with a focus on aesthetic and visual elements (signs, icons, signs, camera movements, scenic compositions) and especially the assembly. The study presented here is a study on the role of the assembly, the documentary film as a historical document and the role of director as "sculptor of the time." For this study, interviews were conducted with experts in this area as well as research and observation of different films and visual arts that address the assembly. Also realize my analysis on some images chosen by director Nikita Mikhalkov who have a vision about this period of Russian history experienced by him along with the growth of his daughter Anna, the heroine of the film object of our study / Mestre
226

Analýza prodejních dat vybrané společnosti se zaměřením na rychloobrátkové zboží / A sell-out data analysis of a particular company with focus on fast moving consumer goods

Kořínková, Martina January 2011 (has links)
The thesis deals with data analysis importance for decision making process. The theoretical part focuses on characteristics and specific attributes of the business intelligence, its history and development, limitations and opportunities. The data processing as well as steps or techniques necessary for the analysis are further examined. The practical part deals with sell-out data analysis of a particular retailer from its supplier point of view. The sell-out data analysis is based on real business examples and results in recommendations for a business team.
227

Efeitos de dois programas de exercícios físicos nas capacidades funcionais e estruturas cerebrais de idosas / Effects of two physical exercise programs in motor capacities and brain structures of elderly women

Maria Cecilia Oliveira da Fonseca 15 March 2010 (has links)
O declínio das capacidades motoras é inevitável ao longo do envelhecimento, porém, a curva desse declínio pode ser reduzida quando o exercício físico é utilizado como forma de intervenção. Em geral, envolvem a repetição de movimentos cíclicos e de baixa complexidade, com o objetivo de aumentar a eficiência fisiológica dos praticantes. Entretanto, há evidências que comprovam a plasticidade cerebral de animais, inclusive em animais idosos, que foram expostos a ambientes e experiências enriquecedoras. Estudos com humanos permitiram observar que os efeitos da aprendizagem de habilidades motoras estão associados a mudanças não apenas comportamentais, mas também nas estruturas cerebrais. Os resultados desses estudos têm sido discutidos em termos do esforço cognitivo relativo ao processo de aprendizagem e, em especial, das habilidades motoras complexas. Neste sentido, este estudo pretendeu verificar os efeitos de dois programas de exercícios físicos nas estruturas cerebrais e capacidades motoras de idosas. Mais especificamente, em uma situação experimental de ensino, foram aplicados dois programas de exercícios físicos, um voltado para a prática de habilidades motoras complexas e o outro voltado especificamente para a prática de movimentos de baixa complexidade (simples). Foram avaliados os efeitos desses programas sobre as estruturas cerebrais, por meio de ressonância magnética cerebral e, também, sobre as capacidades motoras, por meio de testes de capacidade funcional. Participaram do estudo 40 mulheres com idade média de 66,56 anos. Foram formados 3 grupos: Condicionamento Físico, Jogos e Controle. O programa de exercícios teve a duração de 14 semanas, com 3 sessões semanais. As avaliações ocorreram no início e no final dos programas nos 3 grupos. Os resultados revelaram que o grupo controle não apresentou mudanças significantes nas capacidades motoras nem em relação às estruturas cerebrais. O grupo Condicionamento Físico obteve melhora significante no desempenho dos testes de força de membros superiores, flexibilidade de membros inferiores e agilidade/equilíbrio dinâmico. Já o grupo Jogos demonstrou aumento significante no desempenho dos testes de flexibilidade de membros inferiores, agilidade/equilíbrio dinâmico e equilíbrio pé direito olho aberto. Entretanto, nenhum dos grupos, inclusive daqueles que praticaram exercícios físicos, apresentou mudanças significantes no que diz respeito às estruturas cerebrais. Concluiu-se que os programas de exercícios físicos foram parcialmente efetivos para a melhora das capacidades motoras, mas não promoveram alterações na estrutura cerebral / Although the diminishing in the motor abilities is inevitable along the aging process, the tendency of this decrease may be reduced when physical exercise is used as an intervention. These interventions, in general, include the repetition of movements which are cyclical and have low complexity, aiming to increase physiological efficiency of the practitioners. There are evidences of animal\'s brain plasticity, including elderly animals, which have been exposed to enriching environments and experiences. Studies with human beings have lead to the conclusion that the motor learning effects are associated to changes not only behavioral, but also in brain structure. The results of these studies have been discussed in terms of the cognitive effort related to the learning process and, specially, to the complex motor skills. Therefore this study aimed to verify the effects of two programs of physical exercises on the brain structure and motor capacities of elderly women. Specifically, in an experimental teaching condition, there have been developed two physical exercises programs: one oriented to the practice of complex motor skills; and the other directed to the practice of low complexity movements (simple). The effects of these programs in the brain structure have been evaluated through cerebral magnetic resonance and, also, in the motor capacities through functional capacities tests. Forty women with mean age of 66.56 years old have taken part of the study. There were three groups: Fitness, Games and Control. The exercises programs were developed during 14 weeks, with 3 sessions per week. The evaluations were in the beginning and in the end of the program. Results showed that the Control group has neither presented changes in their motor capacities nor related to their brain structures. The Fitness group significantly improved its performance in the tests for upper body strength, flexibility of the limbs and agility/ dynamic balance. The Games group demonstrated significant increase in the test for flexibility of the limbs, agility/dynamic balance and balance right foot open eye. Even though, none of the groups, including those which have practiced physical exercises, presented changes in their brain structures. In conclusion, the physical exercise programs have been partially effective for the improvement of the motor capacities, but have not brought changes in the brain structure
228

Monitoramento dos registros de condenações na população de frangos abatidos no SIF 2485, no período de 1995 a 2005: avaliação das séries históricas e análise crítica / Monitoring condemnation records for poultry hygienic inspection from a federal inspected abattoir (SIF 2485), for 1995 to 2005: time series evaluation and critical analysis

Moretti, Leandro d\'Arc 31 May 2006 (has links)
Apesar do reconhecimento da relevante contribuição epidemiológica dos registros de condenação em abatedouros, é escassa a divulgação sobre estudos referentes às circunstâncias relacionadas com as apreensões em matadouros de frangos. Avaliaram-se dez anos de registros oficiais de condenação em um abatedouro sob inspeção federal no Estado de São Paulo, obtendo-se informações a respeito de 24 causas de apreensão. Análises de tendência, sazonalidade e de componente cíclico foram efetuadas para 21 variáveis. Isto é discutido frente às dificuldades na obtenção sistemática e fidedigna de dados, propondo-se a utilização de programas informatizados para análise dos registros mensais em tempo real, o que possibilita a reavaliação dos programas de controle para as enfermidades desencadeantes das apreensões. Abordaram-se aspectos legislativos da inspeção de aves, enfocando limitações internacionais e particularidades de alguns processos patológicos, sugerindo adequação em determinados procedimentos sanitários. Destacou-se a comparação de dados locais com apreensões de vários países e o impacto interpretativo de diferentes metodologias de análise na concepção das ocorrências. As avaliações permitiram concluir que abordagens informatizadas para sazonalidade e ciclicidade nas séries temporais de apreensões podem incrementar o poder da verificação de programas HACCP. Além disso, observou-se maior poder para revelação de padrões, pela associação dos dois tipos de análise. / There is a lack of studies for circumstances related to poultry abattoir condemnations, despite its wide recognition as a relevant source of epidemiological information. Ten year official condemnation records were issued for one federal inspected slaughterhouse in São Paulo State, Brazil, gathering data about 24 condemnation causes. Global, seasonal and cyclical trends were evaluated for 21 variables, which were further debated concerning trouble reporting of systematic reliable data. Furthermore, the study suggests software packages utilization for real-time monthly data analysis, which in turn leads to control schedules reevaluation for condemnation disease determinants. Legislative approach to poultry inspection, focusing on international limitations and pathological process features were asked for sanitary procedures adequacy. The local and several countries data comparison, besides different analytical methodology impact were highlighted. The conclusion assigns that time series seasonal and cyclical computerized analysis can enhance HACCP\'s verification power and better reveal patterns when combined.
229

Intermittent demand forecasting with integer autoregressive moving average models

Mohammadipour, Maryam January 2009 (has links)
This PhD thesis focuses on using time series models for counts in modelling and forecasting a special type of count series called intermittent series. An intermittent series is a series of non-negative integer values with some zero values. Such series occur in many areas including inventory control of spare parts. Various methods have been developed for intermittent demand forecasting with Croston’s method being the most widely used. Some studies focus on finding a model underlying Croston’s method. With none of these studies being successful in demonstrating an underlying model for which Croston’s method is optimal, the focus should now shift towards stationary models for intermittent demand forecasting. This thesis explores the application of a class of models for count data called the Integer Autoregressive Moving Average (INARMA) models. INARMA models have had applications in different areas such as medical science and economics, but this is the first attempt to use such a model-based method to forecast intermittent demand. In this PhD research, we first fill some gaps in the INARMA literature by finding the unconditional variance and the autocorrelation function of the general INARMA(p,q) model. The conditional expected value of the aggregated process over lead time is also obtained to be used as a lead time forecast. The accuracy of h-step-ahead and lead time INARMA forecasts are then compared to those obtained by benchmark methods of Croston, Syntetos-Boylan Approximation (SBA) and Shale-Boylan-Johnston (SBJ). The results of the simulation suggest that in the presence of a high autocorrelation in data, INARMA yields much more accurate one-step ahead forecasts than benchmark methods. The degree of improvement increases for longer data histories. It has been shown that instead of identification of the autoregressive and moving average order of the INARMA model, the most general model among the possible models can be used for forecasting. This is especially useful for short history and high autocorrelation in data. The findings of the thesis have been tested on two real data sets: (i) Royal Air Force (RAF) demand history of 16,000 SKUs and (ii) 3,000 series of intermittent demand from the automotive industry. The results show that for sparse data with long history, there is a substantial improvement in using INARMA over the benchmarks in terms of Mean Square Error (MSE) and Mean Absolute Scaled Error (MASE) for the one-step ahead forecasts. However, for series with short history the improvement is narrower. The improvement is greater for h-step ahead forecasts. The results also confirm the superiority of INARMA over the benchmark methods for lead time forecasts.
230

Turbulence particle models for tracking free surfaces

Shao, Songdong, Gotoh, H. January 2005 (has links)
No / Two numerical particle models, the Smoothed Particle Hydrodynamics (SPH) and Moving Particle Semi-implicit (MPS) methods, coupled with a sub-particle scale (SPS) turbulence model, are presented to simulate free surface flows. Both SPH and MPS methods have the advantages in that the governing Navier¿Stokes equations are solved by Lagrangian approach and no grid is needed in the computation. Thus the free surface can be easily and accurately tracked by particles without numerical diffusion. In this paper different particle interaction models for SPH and MPS methods are summarized and compared. The robustness of two models is validated through experimental data of a dam-break flow. In addition, a series of numerical runs are carried out to investigate the order of convergence of the models with regard to the time step and particle spacing. Finally the efficiency of the incorporated SPS model is further demonstrated by the computed turbulence patterns from a breaking wave. It is shown that both SPH and MPS models provide a useful tool for simulating free surface flows

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