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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

Global Demand Model to Estimate Supersonic Commercial Services

Freire Burgos, Edwin Ruben 09 November 2021 (has links)
Not too long ago, commercial supersonic aircraft flights were part of the air transportation system. In the 1970's we had the Russian-built Tupolev Tu-144 and the BAC/Aerospatiale Concorde, the latest being tin operation for 27 years. The work documented in this dissertation focused on the viability of bringing back supersonic aircraft as a transportation mode. Throughout three years, Virginia Tech and a team from NASA have been combining efforts to develop a model capable of predicting future air travel demand for supersonic vehicles. The model can predict future supersonic commercial services and allows aircraft designers from NASA to optimize aircraft performance and characteristics by maximizing the potential air travel demand. The final product of this study was the development of the Low-Boom Supersonic Aircraft Model (LBSAM). The development progress took three years to be completed, and during each year, a version of the model with the preliminary predictions was made available to NASA. Each of the three versions of the model predicts future supersonic commercial services. What differentiates each version is the data, method, and aircraft type/design implemented; the latest version of the model is more realistic and provides a higher number of functionalities. The first version of the model predicted the possible supersonic commercial service for three aircraft types: each with two variations. An 18-seat, 40-seat, and 60-seat low-boom and non-low-boom aircraft were analyzed. The second version of the model analyzed a 20-seat and 40-seat low-boom, non-low-boom aircraft with restrictions and non-low-boom aircraft without restrictions. The latest version of the model tries to estimate potential demand for a 43-seat and a 52-seat supersonic low-boom aircraft design. The low-boom concept refers to the implementation of technology that reduces the loudness of a sonic boom. A non-low-boom concept refers to an aircraft flying faster than Mach 1 with the technology's implementation that reduces the loudness of a sonic boom. The final results suggest that for a 52-seat LBSA, the potential worldwide demand is as follows. • 33.4 million seats worldwide. Assuming an overland range of 3,200 nm., an overland Mach 1.7, and an overland fuel scale factor of 0.98. • 772 aircraft needed worldwide. Assuming an overland range of 2,800 nm., an overland Mach 1.7, and an overland fuel scale factor of 0.90. • 1,032 one-way OD pairs where LBSA can operate. Assuming an overland range of 2,800 nm., an overland Mach 1.7, and an overland fuel scale factor of 0.90. The LBSAM is mainly driven by the cost per passenger mile values calculated for each one-way Origin-Destination (OD) pair. Additional uncertainties in the model include the market share and annual aircraft utilization. The market share refers to the percent of the demand that will switch from current subsonic commercial services to commercial supersonic services. During the three-year work, we considered a market share of 50% and 100%. Aircraft utilization refers to the number of hours that the airline will be able to use the aircraft. The majority of the projections were based on a 3,500-hour aircraft utilization. / Doctor of Philosophy / Not too long ago, commercial supersonic aircraft flights were part of the air transportation system. An aircraft flying faster than the speed of sound is known as an aircraft flying at supersonic speed. Current commercial aircraft fly at subsonic speed. Subsonic speed refers to aircraft flying at a speed lower than the speed of sound. In the 1970's we had the Russian-built Tupolev Tu-144 and the BAC/Aerospatiale Concorde, the latest being tin operation for 27 years. The work documented in this dissertation focused on the viability of bringing back supersonic aircraft as a transportation mode. Throughout three years, Virginia Tech and a team from NASA have been combining efforts to develop a model capable of predicting future air travel demand for supersonic vehicles. The model can predict future supersonic commercial services and allows aircraft designers from NASA to optimize aircraft performance and characteristics by maximizing the potential air travel demand. The purpose of this dissertation effort is to provide a better understanding of what could be the potential commercial demand for supersonic flight in the near future. We consider all the benefits and characteristics of supersonic flight and studied in detail what percentage of the travelers might be willing to migrate from the current subsonic market to the supersonic market. We estimated this ratio by studying the spending behavior of passengers in the current market. How much more are passengers willing to pay to save time? We can infer how much travelers value their time by comparing direct flights versus flights with an intermediate stop. The results show that a demand of 33.4 million seats could be reached by the year 2040. The supersonic market would consist of more than one thousand one-way origin-destination pairs worldwide, and more than seven hundred supersonic aircraft are expected to satisfy the forecast demand.
2

A gestão de estoques em sistemas produtivos Engineering-To-Order e Make-To-Stock: estudo de casos em empresas do setor gráfico

Rodrigues, Paulo Cesar Chagas [UNESP] 05 December 2008 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:26:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-05Bitstream added on 2014-06-13T20:34:06Z : No. of bitstreams: 1 rodrigues_pcc_me_bauru.pdf: 661198 bytes, checksum: fd2070d60a4818ea36d1e95ea50627af (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As organizações industriais vêm adotando modelos produtivos que priorizam a redução de custos e aumento da qualidade de seus processos e produtos. Neste contexto a otimização e racionalização da gestão de estoques é uma grande oportunidade para estas empresas conquistarem estes objetivos. Para a realização desta pesquisa optou-se pela metodologia de estudo de casos múltiplos (dois casos), para atender o objetivo de analisar a gestão de estoques em duas empresas do setor gráfico localizadas na região de Bauru, na qual uma adota o sistema produtivo Engineering-To-Order (ETO) e a outra o sistema produtivo Make-To-Stock (MTS). O qual foi alcançado por meio da triangulação dos meios de coleta de dados, ou seja, entrevista semi-estruturada, análise documental e observação in-loco e estes tiveram como embasamento o referencial teórico. Por meio da triangulação das informações obtidas durante a coleta de dados, pôde-se elaborar a descrição da gestão de estoques e do sistema produtivo adotado em cada uma das empresas apresentadas nos estudos de caso e a análise cruzada. Após estes procedimentos foi elaborada a análise da influência do sistema produtivo sobre a gestão de estoques, no qual foram analisados os seguintes itens: produção, previsão de demanda, sazonalidade, layout, gestão de estoques, setup, logística de suprimentos e logística de distribuição. / Industrial organizations are adopting productive models that prioritize the reduction of costs and increase the quality of their processes and products. In this context the optimization and streamlining the inventory management is a great opportunity for these companies conquer these goals. To achieve this research methodology was chosen for the study of multiple cases (two cases), to meet to evaluate the inventory management in two companies in the sector chart located in the region of Bauru, in which one adopts the production system. Which was achieved by means of triangulation of data collection, i.e., semi-structured interviews, document analysis and observation in loco and they were light as the theoretical framework. Through triangulation of information obtained during data collection, it was possible to develop a descritption of the inventory management and the production system used in each of the companies presented in case studies and crossexamination. After these procedures were developed to analyze the influence of the production system on the inventory management, which were analyzed in the following: production, estimates of demand, seasonality, layout, inventory management, setup, logistics supplies and logistics of distribution. While reviewing the analysis of the influence of the production system on the management of inventories could be observed some differences in relation to the literature, they are: logistics supply, distribution, inventory management, production systems Make-To-Stock and Engineering-To-Order.
3

A gestão de estoques em sistemas produtivos Engineering-To-Order e Make-To-Stock : estudo de casos em empresas do setor gráfico /

Rodrigues, Paulo Cesar Chagas. January 2008 (has links)
Orientador: Otávio José de Oliveira / Banca: Fernando Bernardi de Souza / Banca: Marcel Andreotti Musetti / Resumo: As organizações industriais vêm adotando modelos produtivos que priorizam a redução de custos e aumento da qualidade de seus processos e produtos. Neste contexto a otimização e racionalização da gestão de estoques é uma grande oportunidade para estas empresas conquistarem estes objetivos. Para a realização desta pesquisa optou-se pela metodologia de estudo de casos múltiplos (dois casos), para atender o objetivo de analisar a gestão de estoques em duas empresas do setor gráfico localizadas na região de Bauru, na qual uma adota o sistema produtivo Engineering-To-Order (ETO) e a outra o sistema produtivo Make-To-Stock (MTS). O qual foi alcançado por meio da triangulação dos meios de coleta de dados, ou seja, entrevista semi-estruturada, análise documental e observação in-loco e estes tiveram como embasamento o referencial teórico. Por meio da triangulação das informações obtidas durante a coleta de dados, pôde-se elaborar a descrição da gestão de estoques e do sistema produtivo adotado em cada uma das empresas apresentadas nos estudos de caso e a análise cruzada. Após estes procedimentos foi elaborada a análise da influência do sistema produtivo sobre a gestão de estoques, no qual foram analisados os seguintes itens: produção, previsão de demanda, sazonalidade, layout, gestão de estoques, setup, logística de suprimentos e logística de distribuição. / Abstract: Industrial organizations are adopting productive models that prioritize the reduction of costs and increase the quality of their processes and products. In this context the optimization and streamlining the inventory management is a great opportunity for these companies conquer these goals. To achieve this research methodology was chosen for the study of multiple cases (two cases), to meet to evaluate the inventory management in two companies in the sector chart located in the region of Bauru, in which one adopts the production system. Which was achieved by means of triangulation of data collection, i.e., semi-structured interviews, document analysis and observation in loco and they were light as the theoretical framework. Through triangulation of information obtained during data collection, it was possible to develop a descritption of the inventory management and the production system used in each of the companies presented in case studies and crossexamination. After these procedures were developed to analyze the influence of the production system on the inventory management, which were analyzed in the following: production, estimates of demand, seasonality, layout, inventory management, setup, logistics supplies and logistics of distribution. While reviewing the analysis of the influence of the production system on the management of inventories could be observed some differences in relation to the literature, they are: logistics supply, distribution, inventory management, production systems Make-To-Stock and Engineering-To-Order. / Mestre
4

Studie optimalizace plánování zásobovacích procesů se zaměřením na zásoby hotových výrobků / The Study of Optimization of Supply Planning Processes with a Focus on Stocks of Finished Products

Ambrožová, Helena January 2012 (has links)
The diploma thesis deals with the planning system of the stocks of finished products in the company Barum Continental Co., Ltd. This work describes the current state of the supply business process in order to meet the increased requirements during the delivery cycle. Based on the analysis are indentified factors influencing the planning of the stocks of finished products. The practical part of this work includes alternative proposals and recommendation for a more flexible reaction to customer requirements based on processing and monitoring statistical data.

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