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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.
261

Improvement of the mechanical properties of TRIP-assisted multiphase steels by application of innovative thermal or thermomechanical processes

Georges, Cédric 28 August 2008 (has links)
For ecological reasons, the current main challenge of the automotive industry is to reduce the fuel consumption of vehicles and then emissions of greenhouse gas. In this context, steelmakers and automotive manufacturers decided for some years now to join their efforts to promote the development and use of advanced high strength steels such as TRIP steels. A combination of high strength and large elongation is obtained thanks to the TRansformation Induced Plasticity (TRIP) effect. However, improvement of the mechanical properties is still possible, especially by the refinement of the matrix. In this work, two main ways were followed in order to reach improved properties. The classical way consisting of the annealing of cold-rolled samples and an innovative way consisting of obtaining the desired microstructure by direct hot rolling of the samples. In the classical way, this refinement can be obtained by acting on the chemical composition (with such alloying elements like Cu and Nb). It was observed that complete recrystallisation of the ferrite matrix is quite impossible in presence of Cu precipitates. In addition, if the ferrite recrystallisation is not completed before reaching the eutectoid temperature, the recrystallisation will be slowed down by a large way. An innovative heat treatment consisting in keeping the copper in solid solution in the high-Cu steel was developed. Therefore, ferrite recrystallises quite easily and very fine ferrite grains (~1µm) were obtained. In the innovative way, the effects of hot-rolling conditions on TRIP-assisted multiphase steels are of major importance for industrial practice and could open new dimensions for the TRIP steels (i.e. thanks to precipitation mechanisms leading to additive strengthening). Impressive mechanical properties (true stress at maximum load of 1500 MPa and true strain at uniform elongation of 0.22) were obtained with a relatively easy thermomechanical process, the role played by Nb being essential.
262

Využití expozic Botanické zahrady PřF UK v Praze - Vodní a bahenní rostliny / The Using of expositions of the Botanical garden of Faculty of Science, Charles University in Prague - Aquatic and marsh plants

Malcová, Kateřina January 2014 (has links)
Botanical gardens perform a wide variety of functions, from which one of the most important is an educational function. They provide to visitors a large range of services such as guided tours, a variety of educational programs, worksheets etc. The same applies to the Botanical garden of Faculty of Science, Charles University in Prague. The main aim of the thesis was to prepare worksheets concerning expositions of aquatic and marsh plants in already mentioned botanical garden, verify them on students and adjust them to final forms. The results of the thesis are two different versions (spring and autumn) of the worksheets as well as author's solution and methodological manual for teachers. Within the thesis I also implemented the questionnaire survey where I dealt with the issue of teaching the theme of aquatic and marsh plants at Czech grammar schools and examined the attitude of teachers to field trips during botany teaching. Key words: botanical garden, worksheet, aquatic and marsh plants, field trip, questionnaire
263

Naučná stezka Klánovickým lesem s podporou ICT / Nature Trail in the Klanovice Forest with Support ICT

Peterka, Štěpán January 2014 (has links)
This diploma thesis has aimed to elaborate a nature trail in the area of Klánovice Forest, which is the part of a nature park Klánovice - Čihadla in the eastern part of Prague and to complete the trail with electronic educational materials. The nature trail itself will consist of tagg stops enabling visitors to download texts and materials into their cell phones or tablets. The texts of the stops are supplemented with educational presentations, school work sheets and field work sheets. The content of the stops and related teaching materials have been prepared in accordance with systematic teaching of natural history and biology at primary schools and lower grades of grammar schools. The thesis also contains the results of a questionnaire survey of pupils' attitudes towards the use of modern technology at class; 213 questionnaires have been evaluated in total in the years 2008, 2009, 2011 and 2013. The last part of the thesis and appendices contain own texts of stops and related educational materials. In spring 2014 this trail will be realized and educational materials will become a part of the texts on the individual stops and will be available to wide public. Key words: Klánovice Forest, field trip, nature trail, electronic educational materials
264

Roadside

Downing, Lea L 16 May 2014 (has links)
Roadside deals with themes of self-discovery, transcendence, and the search for camaraderie in modern America. Many of the stories take place on or adjacent to the road: that eternal path of transience and transformation. Whether metaphorically or literally on the "roadside," many of the characters contained within are marginalized in their own lives and communities. It is through their grasping and searching for greater meaning in their lives that they come to gain understanding of their places in the world.
265

Um método de utilização de dados de pesquisa embarque/desembarque na calibração de modelos do tipo gravitacional. / A method of use of data of research embarque/desembarque in the calibration of models of distribution of the gravitational type.

Ferreira, Eric Amaral 26 August 1999 (has links)
O objetivo deste trabalho é testar um modelo de distribuição de viagens do tipo gravitacional para a calibração de matrizes origem/destino (O/D) em linhas de transporte público por ônibus a partir de dados de pesquisa de contagem de embarque/desembarque (E/D). A metodologia proposta possibilita a obtenção de matrizes O/D de forma rápida e barata, pois combina um método de pesquisa simples e de baixo custo (pesquisa de contagem de usuários) com um modelo de distribuição de viagens. O modelo associa a cada ponto de origem um valor de parâmetro. A utilização de um valor de parâmetro associado a cada origem busca neste caso reproduzir o custo médio de distribuição de viagens de uma origem em relação aos seus diferentes destinos. O modelo incorpora ainda como restrição a probabilidade de um passageiro desembarcar no ponto seguinte ao seu ponto de embarque. Os dados de pesquisa foram cedidos pelo Departamento de Transportes da Universidade Federal do Paraná. O teste de desempenho do modelo foi realizado através da comparação entre matrizes O/D observadas e simuladas para as cidades de Curitiba e Paranaguá. / The aim of this work is to test a gravity model for trip distribution designed to estimate bus routes origin/destination (O/D) matrices based on boarding and alighting data. The proposed method combines a simple and low-cost survey method (on/off passenger counting) with a mathematical model for trip distribution, which enables the estimation of an O/D matrix in a fast and inexpensive manner. The model assumption that each origin point is associated to a parameter value tries to reproduce the average costs of the actual trip distribution from each origin to every single destination along the bus route. The model brings also as a built-in restriction an expected (usually low) probability of passengers getting off the vehicle in the bus stop following the boarding point. The survey data used in this work have been collected by researchers of the Transportation Department at the Federal University of Paraná. The model performance has been tested by the comparison of observed and simulated O/D matrices in the cities of Curitiba and Paranaguá. The results found in most of the simulations showed that for an estimated trip frequencies did not statistically differ from the actual values for a required level of significance.
266

Um método de utilização de dados de pesquisa embarque/desembarque na calibração de modelos do tipo gravitacional. / A method of use of data of research embarque/desembarque in the calibration of models of distribution of the gravitational type.

Eric Amaral Ferreira 26 August 1999 (has links)
O objetivo deste trabalho é testar um modelo de distribuição de viagens do tipo gravitacional para a calibração de matrizes origem/destino (O/D) em linhas de transporte público por ônibus a partir de dados de pesquisa de contagem de embarque/desembarque (E/D). A metodologia proposta possibilita a obtenção de matrizes O/D de forma rápida e barata, pois combina um método de pesquisa simples e de baixo custo (pesquisa de contagem de usuários) com um modelo de distribuição de viagens. O modelo associa a cada ponto de origem um valor de parâmetro. A utilização de um valor de parâmetro associado a cada origem busca neste caso reproduzir o custo médio de distribuição de viagens de uma origem em relação aos seus diferentes destinos. O modelo incorpora ainda como restrição a probabilidade de um passageiro desembarcar no ponto seguinte ao seu ponto de embarque. Os dados de pesquisa foram cedidos pelo Departamento de Transportes da Universidade Federal do Paraná. O teste de desempenho do modelo foi realizado através da comparação entre matrizes O/D observadas e simuladas para as cidades de Curitiba e Paranaguá. / The aim of this work is to test a gravity model for trip distribution designed to estimate bus routes origin/destination (O/D) matrices based on boarding and alighting data. The proposed method combines a simple and low-cost survey method (on/off passenger counting) with a mathematical model for trip distribution, which enables the estimation of an O/D matrix in a fast and inexpensive manner. The model assumption that each origin point is associated to a parameter value tries to reproduce the average costs of the actual trip distribution from each origin to every single destination along the bus route. The model brings also as a built-in restriction an expected (usually low) probability of passengers getting off the vehicle in the bus stop following the boarding point. The survey data used in this work have been collected by researchers of the Transportation Department at the Federal University of Paraná. The model performance has been tested by the comparison of observed and simulated O/D matrices in the cities of Curitiba and Paranaguá. The results found in most of the simulations showed that for an estimated trip frequencies did not statistically differ from the actual values for a required level of significance.
267

Mário de Andrade fotógrafo: possibilidades de uma câmera moderna / Mário de Andrade photographer: possibilities of a modern camera

Vilela, Viviane Azevêdo 27 October 2017 (has links)
Mário de Andrade e a arte da fotografia é assunto que suscita instigantes questões: de onde teria vindo o interesse em conhecê-­la e praticá-­la? Quais suas relações com ela? Que rastros ou pistas existem sobre isso em suas leituras, em sua biblioteca? Essa última interrogação norteia a presente pesquisa que se debruça sobre a revista Der Querschnitt, assinada pelo escritor paulistano de 1924 a 1931. Nos números deste periódico vanguardista publicado em Berlim, presentes na sua biblioteca, a fotografia destaca-­se nos encartes, somando mais de quatro mil imagens. A dissertação aponta elementos que compreendem Der Querschnitt como a mais significativa matriz conhecida na formação do olhar fotográfico de Mário de Andrade. Para tal, seleciona 19 imagens da autoria de Mário de Andrade no período 1927-­1929, cotejando-­as com 17 fotos escolhidas em Der Querschnitt, no intuito de apontar semelhanças temáticas e estéticas que confirmam a importância da revista no desenvolvimento do olhar do modernista brasileiro. / Mário de Andrade and the art of photography are subjects that incite poignant questions: where did his interest to know it and practice came from? What is his relationship with it? What traces and clues can be found in the titles through his private library? The latter is the questions that guides this research, whilst it focuses on the German magazine Der Querschnitt, subscribed by the author from 1924 to 1931. In the issues of this vanguard publication from Berlin, presented in his library, photography is highlighted throughout over 4 thousand images. This dissertation points out elements that show Der Querschnitt as a big part of Mario de Andrade\'s photographic persona. In order to do so 19 images by Mario de Andrade have been selected, from 1927-­1929, alongside 17 others from the German magazine, making clear the thematic and aesthetic similarities that show just how important the Der Querschnitt\'s publications have been in the upbringing of Brazilian modernism.
268

Improving Vehicle Trip Generation Estimations for Urban Contexts: A Method Using Household Travel Surveys to Adjust ITE Trip Generation Rates

Currans, Kristina Marie 25 July 2013 (has links)
The purpose of this research is to develop and test a widely available, ready-to-use method for adjusting the Institute of Transportation Engineers (ITE) Trip Generation Handbook vehicle trip generation estimates for urban context using regional household travel survey data. The ITE Handbook has become the predominant method for estimating vehicle trips generated by different land uses or establishment, providing a method for data collection and vehicle trip estimation based on the size of the development (e.g. gross square footage, number of employees, number of dwelling units). These estimates are used in traffic impact analysis to assess the amount of impact the development will have on nearby transportation facilities and, the corresponding charges for mitigating the development's negative impacts, with roadway expansions, added turning bays, additional parking or traffic signalization, for example. The Handbook is often criticized, however, for its inability to account for variations in travel modes across urban contexts. For more than fifty years, ITE has collected suburban, vehicle-oriented data on trip generation for automobiles only. Despite the provision of warnings against application in urban areas, local governments continue to require the use of the ITE Handbook across all area-types. By over predicting vehicle traffic to developments in urban developments, developments may be overcharged to mitigate these developments locating in urban environments despite the lower automobile mode shares, discouraging infill development or densification. When ITE's Trip Generation Handbook overestimates the vehicle impact of a development, facilities are also overbuilt for the automobile traffic and diminishing the use of alternative modes. When ITE's TGH underestimates this impact, adjacent facilities may become oversaturated with traffic, pushing cars onto smaller facilities nearby. Currently, there is momentum amongst practitioners to improve these estimation techniques in urban contexts to help support smart growth and better plan for multiple modes. This research developed and tested a method to adjust ITE's Handbook vehicle trip generation estimates for changes in transportation mode shares in more urban contexts using information from household travel surveys. Mode share adjustments provide direct reductions to ITE's Handbook vehicle trip estimations. Household travel survey (HTS) data from three regions were collected: Portland, Oregon; Seattle, Washington; and Baltimore, Maryland. These data were used to estimate the automobile mode share rates across urban context using three different adjustment methodologies: (A) a descriptive table of mode shares across activity density ranges, (B) a binary logistic regression that includes a built environment description of urban context with the best predictive power, and (C) a binary logistic regression that includes a built environment description of urban context with high predictive power and land use policy-sensitivity. Each of these three methods for estimating the automobile mode share across urban context were estimated for each of nine land use categories, resulting in nine descriptive tables (Adjustment A) and eighteen regressions (Adjustments B and C). Additionally, a linear regression was estimated to predict vehicle occupancy rates across urban contexts for each of nine land use categories. 195 independently collected establishment-level vehicle trip generation data were collected in accordance with the ITE Handbook to validate and compare the performance of the three adjustment methods and estimations from the Handbook. Six land use categories (out of the nine estimated) were able to be tested. Out of all of the land uses tested and verified, ITE's Trip Generation Handbook appeared to have more accurate estimations for land uses that included residential condominiums/townhouses (LUC 230), supermarkets (LUC 850) and quality (sit-down) restaurants (LUC 931). Moderate or small improvements were observed when applying urban context adjustments to mid-rise apartments (LUC 223), high-turnover (sit-down) restaurants (LUC 932). The most substantial improvements occurred at high-rise apartments (LUC 222) and condominiums/townhouses (LUC 232), shopping centers (LUC 820), or coffee/donut (LUC 936) or bread/donut/bagel shops (LUC 939) without drive-through windows. The three methods proposed to estimate automobile mode share provides improvements to the Handbook rates for most infill developments in urban environments. For the land uses analyzed, it appeared a descriptive table of mode shares across activity density provided results with comparable improvements to the results from the more sophisticated binary logistic model estimations. Additional independently collected establishment-level data collections representing more land uses, time periods and time of days are necessary to determine how ITE's Handbook performs in other circumstances, including assessing the transferability of the vehicle trip end rates or mode share reductions across regions.
269

Spatial Dynamics and Productivity of a Gulf of Mexico Commercial Reef Fish Fishery Following Large Scale Disturbance and Management Change

Cockrell, Marcy Lynn 18 April 2018 (has links)
The Gulf of Mexico commercial reef fish fishery has experienced significant management changes and disturbance in recent years, including transitioning two major fisheries from a traditional open access system into a limited entry individual fishing quota (IFQ) system in 2007 and 2010. Also in 2010, the Deepwater Horizon oil spill (DWH) released an estimated 4.9 million barrels of oil into the Gulf (~206 million U.S. gallons), and is still the largest U.S. environmental disaster to date. Emergency fishing closures initiated shortly after the oil spill began were successful in keeping tainted seafood from reaching markets. However, effects of DWH closures on fisher decision making, fishery productivity, and distribution of fishing effort all remain poorly understood. Understanding the range and magnitude of fishers’ responses to perturbations — including regulatory change and human-induced environmental disasters — is critical for designing effective management and disaster response policies that can meet biological, ecological, economic, social, and sustainability objectives. This work characterized the spatial and temporal patterns of productivity and fishing effort for the Gulf of Mexico (GoM) commercial reef fish fishery. Patterns of productivity and effort distribution were used to examine the response of fishers to management change and large-scale disturbance, namely the DWH fishing closures. Fisheries-dependent logbook trip reports were used to quantify revenue and catch-per-unit-effort (CPUE) patterns from 2000-2014. Novel to fisheries work in the GoM, complementary vessel monitoring systems (VMS) satellite tracking data were used to quantify high-resolution spatial distribution patterns over time, relative to the DWH fishing closures. A general linear modeling (GLM) approach was also used to examine which variables may have contributed to resilience of fishers after DWH closures. Results suggested that this fishery was largely resilient to the DWH fishing closures in 2010, although exact outcomes varied by region. Overall fleet-level productivity steadily increased over time, but regional patterns were based on major species in catch. Productivity in the western GoM was consistently highest over time, and trips in the west and central GoM were dominated by Red snapper (Lutjanus campechanus) and Vermilion snapper (Rhomboplites aurorubens). Trips in the east were dominated by Red grouper (Epinephelus morio) and Gag grouper (Mycteroperca microlepis). Shifts in spatial distribution to new productive fishing grounds or reduced competition via fewer vessels or trips may explain the increases in productivity observed over the study period. Consolidation in the fleet was apparent, with fewer individual vessels and fewer total trips over time. However, the rate of vessel drop out after DWH (5%) was far below the annual background attrition rate of ~14-20%. Relative productivity patterns inside vs. outside the boundaries of fishing closures did not change over time, and there were even some increases in productivity observed during and after DWH in the eastern GoM. Yet, vessels that dropped out after DWH were concentrated in the north-central and eastern GoM. Distribution of fishing grounds before and after DWH were highly similar, and there were increases in effort along the outer West Florida Shelf. Variability in revenue and CPUE, CPUE magnitude, and magnitude of grouper landings were significant predictors of dropping out of the fishery in the GLMs. Synergies with the Red snapper or Grouper-Tilefish IFQs may have “primed” the fishery for resilience by eliminating inconsistent or marginal fishers before the oil spill, and may further explain some of the spatially varying patterns of productivity and attrition after 2010. Resilience was likely also enhanced by the more than $2 billion in emergency compensation payments made to captains, crew, and vessel owners for lost fishing income and assistance with oil remediation efforts. This work stands to make a significant contribution to our understanding of how the DWH oil spill impacted fisheries and communities in the GoM. The results add to a growing body of literature suggesting that the acute population- and ecosystem-level impacts of the DWH oil spill were not as strong or severe as initially anticipated. This work also stands to make contributions to the broader understanding of how this fishery has performed in the wake of recent management change and major environmental disturbance.
270

Étude du comportement post-coulée de réfractaires électrofondus à Très Haute Teneure en Zircone (THTZ)

Petroni, Laetitia 09 September 2011 (has links) (PDF)
Cette étude, inscrite dans le Programme National de Recherche NOREV (Nouveaux REfractaires Verriers), porte sur la simulation numérique par éléments finis du refroidissement post-coulée de réfractaires électrofondus à très haute teneur en zircone (THTZ). Un modèle numérique thermique du refroidissement d'une dalle a été développé, à partir de mesures thermiques réalisées dans un moule lors d'une coulée en usine. Ce calcul a permis de situer dans le temps, pour les différents points de la dalle, les phénomènes intervenant au cours du refroidissement : solidification, fluage et transformation de la zircone. Des essais mécaniques isothermes et anisothermes ont permis de définir les équations constitutives du comportement en fluage (écrouissage isotrope) et lors de la transformation de phase de la zircone (modèle de plasticité de transformation de Leblond). A partir des chargements thermiques, les contraintes générées au cours du refroidissement ont été calculées, ainsi que les contraintes résiduelles après retour à température ambiante. La transformation de phase de la zircone, qui induit un gonflement volumique de 4%, semble s'avérer être le phénomène physique le plus critique pour ces deux types de contraintes. Les études paramétriques réalisées ont prouvé l'intérêt du modèle numérique en tant qu'outil d'aide à l'amélioration du procédé en jouant sur les propriétés de divers paramètres : propriétés du matériau coulé, géométrie du moule, propriétés de ses constituants,...

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