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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.
11

Investigação de opções de transporte de carga geral em contêineres nas conexões com a região amazônica / Options investigation of the general cargo transport in containers in the connections with the amazon region

Teixeira, Karênina Martins 01 October 2007 (has links)
Comércio e indústria, atualmente, respondem por parcela significativa do produto interno bruto (PIB) do Brasil e juntos demandam significativa quantidade de transporte de carga, principalmente do tipo fracionada, fato que, nos últimos anos provocou o crescimento do transporte desse tipo de carga. O elevado crescimento industrial, em 2004 e 2005, nos principais estados da região norte do país, Amazonas e Pará, indicam o aumento potencial da demanda por transporte de carga fracionada entre o norte e o sudeste, que concentra o maior mercado consumidor. As grandes distâncias, entre o norte e o sudeste, fazem o custo de transporte ter grande impacto significativo no preço final das mercadorias. Esse fato levou à procura por opções de transporte de menor custo, para tornar os produtos fabricados na região norte mais competitivos no mercado interno. Atualmente, existe predominância do transporte rodoviário no corredor norte-sudeste, o que desperdiça, por hipótese, o potencial de outros modos de transporte, como cabotagem, transporte fluvial e, futuramente, transporte ferroviário (Ferrovia Norte-Sul e Ferronorte). Isso motivou o desenvolvimento desta pesquisa, que tem como objetivo avaliar opções de transporte intermodal, econômica e operacionalmente mais atraentes que as praticadas hoje no transporte de carga geral fracionada (produtos e insumos industrializados) em conexões com a região amazônica. A metodologia empregada no trabalho utilizou: (1) técnica de construção de cenários; (2) modelos de custo de transporte para os modos rodoviário, ferroviário, marítimo e fluvial; e (3) sistema de informação geográfica. Os resultados obtidos nesta tese indicam que opções de rotas rodo-marítimas e rodo-fluviais apresentam significativas reduções no custo total de transporte com relação às rotas preferenciais, hoje, praticadas para as ligações entre Belém-São Paulo e Manaus-São Paulo. Os resultados mostram, também, não haver perspectivas para o transporte rodo-ferroviário e rodo-fluvial-ferroviário nessas ligações, uma vez que, neste caso, o custo obtido é maior que os das rotas hoje praticadas. / Nowadays, business and industry are responsible for a significant portion of the GDP (Gross Domestic Product) in Brazil, and together they require a considerable amount of freight transport, mainly break-bulk cargo which has stimulated the transport growth of this kind of cargo. The enormous industrial growth in the most important states of the northern region of the country in the years 2004 and 2005 indicate the potential increase of break-bulk cargo transport between the north and the southeast, area that concentrates the strongest consumer market in the country. Due to the long distance between the country\'s north and southeastern regions, the cost of transport increases the final cost of the goods. This fact led to the search for lower cost transport options in order to make the products of that region more competitive in the domestic market. Currently there has been predominance of road transport in the north/southeast corridor wasting, hypothetically, the potential of other means of transport such as cabotage, river, and, in the future, railroad transport (Norte-Sul and Ferronorte railways). All of this brought about the development of this research which aims at evaluating the intermodal transport options that are economically and operationally more attractive than the break-bulk cargo transport (industrial input and products) used today in the connections with the amazon region. The methodology involves: (1) scenario building; (2) transport cost models for the road, railroad, and marine means; and (3) geographic information system. The results demonstrate that the route options road-marine and road-river show substantial reduction in the transport total cost when compared to the most popular routes used between Belém-São Paulo and Manaus-São Paulo. The results also reveal that there is no perspective of the use of road-rail and road-river-rail transport in such connections since the cost is higher than in the routes used nowadays.
12

Cost model for bipolar plate manufacture

Atkinson, Juan Pablo 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This thesis gives a cost model for the manufacture of bipolar plates in South Africa. The methods for the manufacture considered are machining, using a micro-milling machine, and compression moulding. The focus of this thesis is on compression moulding. Details of the work done towards developing and validating the models are described, and then the cost models are discussed in detail. The results of the analysis done using the cost model is given with attention paid to the effect of changing design parameters, such as channel size and flow field area, and of the cost of production for both methods over various production volumes. The thesis concludes that compression moulding becomes the better option for production volumes greater than 324 bipolar plates, with a cost that eventually reaches close to R140 per plate for high enough production volumes (over 5000). The cost to produce 1000 plates using compression moulding is estimated at R294 per plate. An increase of the channel size gives a small reduction in the total cost, while the increase in cost with an increase in flow field area is large. / AFRIKAANSE OPSOMMING: Hierdie tesis gee 'n koste-model vir die vervaardiging van bipolêre plate in Suid- Afrika. Die vervaardigingsmetodes wat oorweeg word, is masjinering deur 'n mikro-freesmasjien en persvorming. Die fokus van hierdie tesis is op persvorming. Die besonderhede van die ontwikkeling en validering van die modelle word beskryf, en daarna word die modelle in besonderhede beskryf. Die resultate van 'n analise wat met die koste-model gedoen is, word daarna gegee, met die oorweging van die verandering van ontwerp-parameters soos die vloeikanaalgrootte en vloeiveld-area, en van die koste van vervaardiging vir beide metodes vir verskeie produksievolumes. Die tesis kom tot die slotsom dat persvorming die voorkeurproses is vir produksievolumes groter as 324 bipolêre plate, met 'n koste wat tot naastenby R140 per plaat daal vir hoë produksievolumes (meer as 5000). Die koste om 1000 plate met persvorming te maak, word op R294 per plaat beraam. 'n Toename in kanaalgrootte gee 'n klein vermindering in die totale koste, terwyl die toename in koste groot is wanneer die vloeiveld-area toeneem.
13

Liquid metal based high temperature concentrated solar power: Cost considerations

Wilk, Gregory 27 May 2016 (has links)
Current concentrated solar power plants (CSP) use molten salt at 565°C as a heat transfer and energy storage fluid. Due to thermal energy storage (TES), these solar plants can deliver dispatachable electricity to the grid; however, the levelized cost of electricity (LCOE) for these plants is 12-15 c/kWh, about 2.5 times as high as fossil fuel electricity generation. Molten salt technology limits peak operating temperatures to 565°C and a heat engine efficiency of 40%. Liquid metal (LM), however, can reach >1350°C, and potentially utilize a more efficient (60%) heat engine and realize cost reductions. A 1350 °C LM-CSP plant would require ceramic containment, inert atmosphere containment, additional solar flux concentration, and redesigned internal receiver. It was initially unclear if these changes and additions for LM-CSP were technically feasible and could lower the LCOE compared to LS-CSP. To answer this question, a LM-CSP plant was designed with the same thermal input as a published LS-CSP plant. A graphite internal cavity receiver with secondary concentration heated liquid Sn to 1400°C and transferred heat to a 2-phase Al-Si fluid for 9 hours of thermal energy storage. Input heat to the combined power cycle was 1350°C and had 60% thermal efficiency for a gross output of 168 MW. The cost of this LM-CSP was estimated by applying material cost factors to the designed geometry and scaling construction costs from published LS-CSP estimates. Furthermore, graphite was experimentally tested for reactivity with liquid Sn, successful reaction bonds, and successful mechanical seals. The result is switching to molten metal can reduce CSP costs by 30% and graphite pipes, valves, and seals are possible at least at 400°C.
14

Design analysis of a lomolding machine

Goussard, Charl Leonard 12 1900 (has links)
Thesis (PhD (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / This dissertation describes the design analysis of a lomolder (a machine similar to an injection moulding machine). It focuses on key design aspects that will drive the purchase cost of the machine and that will also influence the maintenance and operating cost. The main objective of the study is to provide an understanding of the key factors that influence the cost of a lomolder as well as the factors that contributes to a quality manufactured part. A semi-analytical flow model was developed to predict cavity pressure drops for a range of part sizes. This model was necessary to eliminate time consuming numeric simulations required for machine optimisation. Numerous machine concept designs were developed and a final layout design chosen. A parametric CAD model was built for the lomolder. Layout designs for different sized lomolders can be generated with this model. The dissertation concludes with a cost study that focuses on the purchase cost of a lomolder unit. Key elements such as choice of actuator and piston to part area ratio are described.
15

Cost-Effective Resource Configurations for Executing Data-Intensive Workloads in Public Clouds

Mian, Rizwan 04 December 2013 (has links)
The rate of data growth in many domains is straining our ability to manage and analyze it. Consequently, we see the emergence of computing systems that attempt to efficiently process data-intensive applications or I/O bound applications with large data. Cloud computing offers “infinite” resources on demand, and on a pay-as-you-go basis. As a result, it has gained interest for large-scale data processing. Given this supposedly infinite resource set, we need a provisioning process to determine appropriate resources for data processing or workload execution. We observe that the prevalent data processing architectures do not usually employ provisioning techniques available in a public cloud, and existing provisioning techniques have largely ignored data-intensive applications in public clouds. In this thesis, we take a step towards bridging the gap between existing data processing approaches and the provisioning techniques available in a public cloud, such that the monetary cost of executing data-intensive workloads is minimized. We formulate the problem of provisioning and include constructs to exploit a cloud’s elasticity to include any number of resources to host a multi-tenant database system prior to execution. The provisioning is modeled as a search problem, and we use standard search heuristics to solve it. We propose a novel framework for resource provisioning in a cloud environment. Our framework allows pluggable cost and performance models. We instantiate the framework by developing various search algorithms, cost and performance models to support the search for an effective resource configuration. We consider data-intensive workloads that consist of transactional, analytical or mixed workloads for evaluation, and access multiple database tenants. The workloads are based on standard TPC benchmarks. In addition, the user preferences on response time or throughput are expressed as constraints. Our propositions and their results are validated in a real public cloud, namely the Amazon cloud. The evaluation supports our claim that the framework is an effective tool for provisioning database workloads in a public cloud with minimal dollar cost. / Thesis (Ph.D, Computing) -- Queen's University, 2013-11-30 19:30:39.427
16

Proposition d'un cadre générique d'optimisation de requêtes dans les environnements hétérogènes et répartis / On a generic framework for query optimization in heterogeneous and distributed environments

Liu, Tianxao 06 June 2011 (has links)
Dans cette thèse, nous proposons un cadre générique d'optimisation de requêtes dans les environnements hétérogènes répartis. Nous proposons un modèle générique de description de sources (GSD), qui permet de décrire tous les types d'informations liées au traitement et à l'optimisation de requêtes. Avec ce modèle, nous pouvons en particulier obtenir les informations de coût afin de calculer le coût des différents plans d'exécution. Notre cadre générique d'optimisation fournit les fonctions unitaires permettant de mettre en œuvre les procédures d'optimisation en appliquant différentes stratégies de recherche. Nos résultats expérimentaux mettent en évidence la précision du calcul de coût avec le modèle GSD et la flexibilité de notre cadre générique d'optimisation lors du changement de stratégie de recherche. Notre cadre générique d'optimisation a été mis en œuvre et intégré dans un produit d'intégration de données (DVS) commercialisé par l'entreprise Xcalia - Progress Software Corporation. Pour des requêtes contenant beaucoup de jointures inter-site et interrogeant des sources de grand volume, le temps de calcul du plan optimal est de l'ordre de 2 secondes et le temps d'exécution du plan optimal est réduit de 28 fois par rapport au plan initial non optimisé. / This thesis proposes a generic framework for query optimization in heterogeneous and distributed environments. We propose a generic source description model (GSD), which allows describing any type of information related to query processing and optimization. With GSD, we can use cost information to calculate the costs of execution plans. Our generic framework for query optimization provides a set of unitary functions used to perform optimization by applying different search strategies. Our experimental results show the accuracy of cost calculus when using GSD, and the flexibility of our generic framework when changing search strategies. Our proposed approach has been implemented and integrated in a data integration product (DVS) licensed by Xcalia – Progress Software Corporation. For queries with many inter-site joins accessing large size data sources, the time used for finding the optimal plan is in the order of 2 seconds, and the execution time of the optimized plan is reduced by 28 times, as compared with the execution time of the non optimized original plan.
17

Modelo de custo para consultas por similaridade em espaços métricos / Cost model for similarity queries in metric spaces

Baioco, Gisele Busichia 24 January 2007 (has links)
Esta tese apresenta um modelo de custo para estimar o número de acessos a disco (custo de I/O) e o número de cálculos de distância (custo de CPU) para consultas por similaridade executadas sobre métodos de acesso métricos dinâmicos. O objetivo da criação do modelo é a otimização de consultas por similaridade em Sistemas de Gerenciamento de Bases de Dados relacionais e objeto-relacionais. Foram considerados dois tipos de consultas por similaridade: consulta por abrangência e consulta aos k-vizinhos mais próximos. Como base para a criação do modelo de custo foi utilizado o método de acesso métrico dinâmico Slim-Tree. O modelo estima a dimensão intrínseca do conjunto de dados pela sua dimensão de correlação fractal. A validação do modelo é confirmada por experimentos com conjuntos de dados sintéticos e reais, de variados tamanhos e dimensões, que mostram que as estimativas obtidas em geral estão dentro da faixa de variação medida em consultas reais / This thesis presents a cost model to estimate the number of disk accesses (I/O costs) and the number of distance calculations (CPU costs) to process similarity queries over data indexed by dynamic metric access methods. The goal of the model is to optimize similarity queries on relational and object-relational Database Management Systems. Two types of similarity queries were taken into consideration: range queries and k-nearest neighbor queries. The dynamic metric access method Slim-Tree was used as the basis for the creation of the cost model. The model takes advantage of the intrinsic dimension of the data set, estimated by its correlation fractal dimension. Experiments were performed on real and synthetic data sets, with different sizes and dimensions, in order to validate the proposed model. They confirmed that the estimations are accurate, being always within the range achieved executing real queries
18

Proposta de um modelo de custos para um consultório odontológico

Cunha, Gerson de Simas January 2015 (has links)
No momento de crise econômica que o país enfrenta atualmente, a prestação de serviços de saúde necessita cada vez mais a busca de alternativas que possibilitem uma melhor gestão de custos, a fim de enfrentar o mercado cada vez mais restrito e competitivo. Com o propósito de investigar as dificuldades enfrentadas pelos cirurgiões-dentistas, no que tange a gestão de custos, foi realizada uma pesquisa sobre como o profissional percebe sua atividade como negócio. A qual indicou a necessidade de uma ferramenta de apuração de custos para seus consultórios. Desta forma, este trabalho trata da gestão de custos eficiente em uma empresa prestadora de serviços e o predomínio do uso do sistema de custeio por absorção no Brasil, objetivando responder qual o custo da prestação de serviços, apurado pelo sistema de custeio por absorção, de um consultório odontológico. Como objetivos específicos, este trabalho busca descrever os principais serviços oferecidos por um consultório odontológico; bem como apresentar as principais vantagens e desvantagens do sistema de custeio por absorção quando utilizado neste local. Finalizando, com a apresentação de um modelo de apuração de custo de um procedimento na prestação de serviços oferecidos em um consultório odontológico. Com isso, será possibilitada, mesmo de forma singela, uma alternativa de projeção de custos, através da aplicação do custeio por absorção no procedimento de restauração em resina fotopolimerizável classe II e IV. Este modelo de apuração de custos permite que sua aplicação seja utilizada em diversos modos e atividades desempenhadas pelos cirurgiões-dentistas com intuito de mensurar o valor dos procedimentos odontológicos em seus consultórios. / During the economic crisis Brazil is currently facing, the provider of health services needs to seek better cost management alternatives in order to face the increasingly restricted and competitive market. In order to understand the difficulties faced by dentists regarding cost management, research was made on how dentists plan their business, leading to the conclusion that some tool for cost calculation is necessary in their clinics. This work studies the efficient cost management in a service company and the predominance of the absorption costing system in Brazil, using this system to calculate the costs of a dentist’s clinic. . As specific goals, this study seeks to describe the main services offered by a dental office as well as to show the main advantages and disadvantages of the absorption cost system in this context. Finally, a cost calculation model is used to analyze the procedure of restoring light-cured resins class II and IV. With this analysis, we concluded that it is possible to make a simple yet effective cost projection of this type of service by using the absorption calculation model, which might be prove to be an efficient way to measure the cost of dental procedures.
19

Investigação de opções de transporte de carga geral em contêineres nas conexões com a região amazônica / Options investigation of the general cargo transport in containers in the connections with the amazon region

Karênina Martins Teixeira 01 October 2007 (has links)
Comércio e indústria, atualmente, respondem por parcela significativa do produto interno bruto (PIB) do Brasil e juntos demandam significativa quantidade de transporte de carga, principalmente do tipo fracionada, fato que, nos últimos anos provocou o crescimento do transporte desse tipo de carga. O elevado crescimento industrial, em 2004 e 2005, nos principais estados da região norte do país, Amazonas e Pará, indicam o aumento potencial da demanda por transporte de carga fracionada entre o norte e o sudeste, que concentra o maior mercado consumidor. As grandes distâncias, entre o norte e o sudeste, fazem o custo de transporte ter grande impacto significativo no preço final das mercadorias. Esse fato levou à procura por opções de transporte de menor custo, para tornar os produtos fabricados na região norte mais competitivos no mercado interno. Atualmente, existe predominância do transporte rodoviário no corredor norte-sudeste, o que desperdiça, por hipótese, o potencial de outros modos de transporte, como cabotagem, transporte fluvial e, futuramente, transporte ferroviário (Ferrovia Norte-Sul e Ferronorte). Isso motivou o desenvolvimento desta pesquisa, que tem como objetivo avaliar opções de transporte intermodal, econômica e operacionalmente mais atraentes que as praticadas hoje no transporte de carga geral fracionada (produtos e insumos industrializados) em conexões com a região amazônica. A metodologia empregada no trabalho utilizou: (1) técnica de construção de cenários; (2) modelos de custo de transporte para os modos rodoviário, ferroviário, marítimo e fluvial; e (3) sistema de informação geográfica. Os resultados obtidos nesta tese indicam que opções de rotas rodo-marítimas e rodo-fluviais apresentam significativas reduções no custo total de transporte com relação às rotas preferenciais, hoje, praticadas para as ligações entre Belém-São Paulo e Manaus-São Paulo. Os resultados mostram, também, não haver perspectivas para o transporte rodo-ferroviário e rodo-fluvial-ferroviário nessas ligações, uma vez que, neste caso, o custo obtido é maior que os das rotas hoje praticadas. / Nowadays, business and industry are responsible for a significant portion of the GDP (Gross Domestic Product) in Brazil, and together they require a considerable amount of freight transport, mainly break-bulk cargo which has stimulated the transport growth of this kind of cargo. The enormous industrial growth in the most important states of the northern region of the country in the years 2004 and 2005 indicate the potential increase of break-bulk cargo transport between the north and the southeast, area that concentrates the strongest consumer market in the country. Due to the long distance between the country\'s north and southeastern regions, the cost of transport increases the final cost of the goods. This fact led to the search for lower cost transport options in order to make the products of that region more competitive in the domestic market. Currently there has been predominance of road transport in the north/southeast corridor wasting, hypothetically, the potential of other means of transport such as cabotage, river, and, in the future, railroad transport (Norte-Sul and Ferronorte railways). All of this brought about the development of this research which aims at evaluating the intermodal transport options that are economically and operationally more attractive than the break-bulk cargo transport (industrial input and products) used today in the connections with the amazon region. The methodology involves: (1) scenario building; (2) transport cost models for the road, railroad, and marine means; and (3) geographic information system. The results demonstrate that the route options road-marine and road-river show substantial reduction in the transport total cost when compared to the most popular routes used between Belém-São Paulo and Manaus-São Paulo. The results also reveal that there is no perspective of the use of road-rail and road-river-rail transport in such connections since the cost is higher than in the routes used nowadays.
20

Externredovisningens värderingsproblem rörande förvaltningsfastigheter : en jämförelse i synen på förändringen mellan börsnoterade och allmännyttiga fastighetsbolag

Sjöberg, Olof January 2004 (has links)
No description available.

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