• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 20
  • 4
  • 2
  • 2
  • 1
  • Tagged with
  • 32
  • 32
  • 13
  • 12
  • 9
  • 7
  • 6
  • 6
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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

Development of an Endoscope Propulsion System to Aid in the Colonoscopy Procedure

Tenga, Ryan Richard 16 January 2008 (has links)
Colorectal cancer is the third most common form of cancer, and is the number two cancer-related death in the United States. Receiving regular colonoscopies can reduce the average person's risk of dying from colon cancer by 90%. However, only 54% if adults over the age of 50 get regular colonoscopies. This low percentage can be attributed to the exam's poor availability, severe discomfort, high cost, and the risk of procedural complications. The Endoscope Propulsion System, or EPS, will assist in the colonoscopy procedure. This device will enable a lesser skilled physician to effectively perform the colonoscopy, thus increasing the procedure's availability. In addition to requiring less skill, the assistive nature of the EPS will also decrease the chance of complications due to colon perforation. The EPS will greatly reduce the discomfort cause by the colonoscope, which will eliminate the need for anesthesia and recovery, therefore greatly reducing the cost of the procedure. The Endoscope Propulsion System design described in this paper is an update to the device outlined in Dr. M. Jonathan Bern's patent application (20060270901). The criteria and requirements of the design are discussed along with the final design and analysis. Finally, a prototype was built to ensure the validity of the proposed invention. / Master of Science
2

Turboelectric Distributed Propulsion System for NASA Next Generation Aircraft

Abada, Hashim H. January 2017 (has links)
No description available.
3

Metodologia de dimensionamento do sistema de tração para veículos elétricos. / Methodology of propulsion system design of electric vehicles.

Tanaka, Carlos Naomi 10 December 2012 (has links)
O interesse por veículos elétricos voltou a crescer nos últimos anos, principalmente, devido às questões ambientais e de eficiência energética. Aliado ao desenvolvimento de fontes e acumuladores de energia com densidades de energia e potência maiores que viabilizam a utilização de veículos elétricos em substituição parcial dos veículos com motores a combustão interna, já surgem comercialmente no mercado alguns modelos de veículos elétricos. Neste contexto, também cresce a necessidade de recursos humanos capacitados e ferramentas auxiliares para o dimensionamento dos componentes dessa nova geração de veículos automotores. Este trabalho apresenta uma metodologia simples e direta de dimensionamento do sistema de tração para veículos elétricos autônomos, bem como os resultados de uma aplicação prática da utilização desta metodologia no desenvolvimento de veículos elétricos fora de estrada para transporte de pessoas e de material. A comparação entre os resultados práticos obtidos com os cálculos realizados mostra que a metodologia, com o equacionamento completo e abrangente apresentado, fornece resultados com excelente exatidão. / The interest in electric vehicles is growing again in recent years, mainly due to environmental concerns and energy efficiency issues. Combined with the development of energy storage devices with higher power and energy densities that enable the use of electric vehicles, some models already appear commercially in the market replacing vehicles with internal combustion engines in specific applications. In this context, it also increases the need for trained human resources and auxiliary tools for designing the components of this new vehicles generation. This dissertation presents a simple and direct methodology of propulsion system design for autonomous electric vehicles as well as the results of a practical application of using this methodology in the development of off-road electric vehicles for people and material transport. The comparison between the practical results obtained with the calculations shows that the methodology, with the complete and comprehensive equations presented, provides results with excellent accuracy.
4

Metodologia de dimensionamento do sistema de tração para veículos elétricos. / Methodology of propulsion system design of electric vehicles.

Carlos Naomi Tanaka 10 December 2012 (has links)
O interesse por veículos elétricos voltou a crescer nos últimos anos, principalmente, devido às questões ambientais e de eficiência energética. Aliado ao desenvolvimento de fontes e acumuladores de energia com densidades de energia e potência maiores que viabilizam a utilização de veículos elétricos em substituição parcial dos veículos com motores a combustão interna, já surgem comercialmente no mercado alguns modelos de veículos elétricos. Neste contexto, também cresce a necessidade de recursos humanos capacitados e ferramentas auxiliares para o dimensionamento dos componentes dessa nova geração de veículos automotores. Este trabalho apresenta uma metodologia simples e direta de dimensionamento do sistema de tração para veículos elétricos autônomos, bem como os resultados de uma aplicação prática da utilização desta metodologia no desenvolvimento de veículos elétricos fora de estrada para transporte de pessoas e de material. A comparação entre os resultados práticos obtidos com os cálculos realizados mostra que a metodologia, com o equacionamento completo e abrangente apresentado, fornece resultados com excelente exatidão. / The interest in electric vehicles is growing again in recent years, mainly due to environmental concerns and energy efficiency issues. Combined with the development of energy storage devices with higher power and energy densities that enable the use of electric vehicles, some models already appear commercially in the market replacing vehicles with internal combustion engines in specific applications. In this context, it also increases the need for trained human resources and auxiliary tools for designing the components of this new vehicles generation. This dissertation presents a simple and direct methodology of propulsion system design for autonomous electric vehicles as well as the results of a practical application of using this methodology in the development of off-road electric vehicles for people and material transport. The comparison between the practical results obtained with the calculations shows that the methodology, with the complete and comprehensive equations presented, provides results with excellent accuracy.
5

Next Generation Nanosatellite Systems: Mechanical Analysis and Test

Ligori, Michael C. 14 December 2011 (has links)
The Canadian Nanosatellite Advanced Propulsion System is the second generation cold-gas propulsion system. Its purpose is to provide the millinewton thrust required for formation control of nanosatellites, in particular the CanX-4/-5 formation flying mission. Additionally, to inject nanosatellites into orbit, a reliable and robust deployer is needed to bridge the gap between the launch vehicle and space. This bridge is the XPOD, the eXoadaptable PyrOless Deployer. Both of these technologies are designed and developed by the Space Flight Lab. This thesis describes the assembly, integration and preliminary testing of the CanX-4/-5 propulsion system. Emphasis is placed on the phases involved with the assembly and integration while highlighting the problems encountered and lessons learned. In addition, the mechanical analysis of the XPOD as well as its assembly and testing is described in detail.
6

Next Generation Nanosatellite Systems: Mechanical Analysis and Test

Ligori, Michael C. 14 December 2011 (has links)
The Canadian Nanosatellite Advanced Propulsion System is the second generation cold-gas propulsion system. Its purpose is to provide the millinewton thrust required for formation control of nanosatellites, in particular the CanX-4/-5 formation flying mission. Additionally, to inject nanosatellites into orbit, a reliable and robust deployer is needed to bridge the gap between the launch vehicle and space. This bridge is the XPOD, the eXoadaptable PyrOless Deployer. Both of these technologies are designed and developed by the Space Flight Lab. This thesis describes the assembly, integration and preliminary testing of the CanX-4/-5 propulsion system. Emphasis is placed on the phases involved with the assembly and integration while highlighting the problems encountered and lessons learned. In addition, the mechanical analysis of the XPOD as well as its assembly and testing is described in detail.
7

Modelling, design and energy management of a hybrid electric ship – a case study

Zhu, Haijia 05 May 2020 (has links)
The widely-used passenger and car ferries, sailing regularly and carrying heavy loads, form a unique type of marine vessel, providing vital transportation links to the coastal regions. Modern ferry ships usually are equipped with multiple diesel engines as prime movers. These diesel engines consume a large amount of marine diesel fuel with high fuel costs, and high emissions of greenhouse gas (GHG) and other harmful air pollutants, including CO2, HC, NOx, SO2, CO, and PM. To reduce fuel costs and the harmful emissions, the marine industry and ferry service providers have been seeking clean ship propulsion solutions. In this work, the model-based design (MBD) and optimization methodology for developing advanced electrified vehicles (EV) are applied to the modelling, design and control optimizations of clean marine vessels with a hybrid electric propulsion system. The research focuses on the design and optimization of the hybrid electric ship propulsion system and uses an open deck passenger and car ferry, the MV Tachek, operated by the British Columbia Ferry Services Inc. Canada, as a test case. At present, the ferry runs on the Quadra Island – Cortes Island route in British Columbia, Canada, with dynamically changing ocean conditions in different seasons over a year. The research first introduces the ship operation profile, using statistical ferry operation data collected from the ferry’s voyage data recorder and a data acquisition system that is specially designed and installed in this research. The ship operation profile model with ship power demand, travelling velocity and sailing route then serves as the design and control requirements of the hybrid electric marine propulsion system. The development of optimal power control and energy management strategies and the optimization of the powertrain architecture and key powertrain component sizes of the ship propulsion system are then carried out. Both of the series and parallel hybrid electric propulsion architectures have been studied. The sizes of crucial powertrain components, including the diesel engine and battery energy storage system (ESS), are optimized to achieve the best system energy efficiency. The optimal power control and energy management strategies are optimized using dynamic programming (DP) over a complete ferry sailing trip. The predicted energy efficiency and emission reduction improvements of the proposed new ship with the optimized hybrid propulsion system are compared with those of two benchmark vessels to demonstrate the benefits of the new design methodology and the optimized hybrid electric ship propulsion system design. These two benchmarks include a conventional ferry with the old diesel-mechanical propulsion system, and the Power Take In (PTI) hybrid electric propulsion systems installed on the MV Tachek at present. The simulation results using the integrated ship propulsion system model showed that the newly proposed hybrid electric ship could have 17.41% fuel saving over the conventional diesel-mechanical ship, and 22.98% fuel saving over the present MV Tachek. The proposed optimized hybrid electric propulsion system, combining the advantages of diesel-electric, pure electric, and mechanical propulsions, presented considerably improved energy efficiency and emissions reduction. The research forms the foundation for future hybrid electric ferry design and development. / Graduate
8

Application of boundary element methods (BEM) to internal propulsion systems; application to water-jets and inducers

Valsaraj, Alokraj 2013 August 1900 (has links)
A panel method derived from inviscid irrotational flow theory and utilizing hyperboloid panels is developed and applied to the simulation of steady fully wetted flows inside water-jet pumps and rocket engine inducers. The source and dipole influence coefficients of the hyperboloid panels are computed using Gauss quadrature. The present method solves the boundary value problem subject to a uniform inflow directly by discretizing the blade, casing/shroud and hub geometries with panels. The Green's integral equation and the influence coefficients for the water-jet/inducer problem are defined and solved by allocating constant strength sources and dipoles on the blade, hub and casing surfaces and constant strength dipoles on the shed wake sheets from the rotor/ stator blades. The rotor- stator interaction is accomplished using an iterative procedure which considers the effects between the rotor and the stator, via circumferentially averaged induced velocities. Finally, the hydrodynamic performance predictions for the water-jet pump and the inducer from the present method are validated against existing experimental data and numerical results from Reynolds Averaged Navier- Stokes (RANS) solvers. / text
9

Sustainable Autonomous Solar UAV with Distributed Propulsion System

Shupeng Liu (9762536) 04 January 2021 (has links)
<p>Solar-powered Unmanned Aerial Vehicles (UAVs) solve the problem of loiter time as aircrafts can fly as long as sufficient illumination and reserve battery power is available. However, Solar-powered UAVs still face the problem of excessive wingspan to increase solar capture area, which detracts from maneuverability and portability. As a result, a feature of merit for solar UAVs has emerged that strives to reduce the wingspan of such UAVs. The purpose of this project is to improve energy use efficiency by applying a distributed propulsion system to reduce the wingspan of solar-powered UAVs and increase payload. The research focuses on optimizing a new design analysis method applied to the distributed propulsion system and further employs the novel application of solar arrays on both top and bottom of the wings. The design methodology will result in a 2.1-meter wingspan, which is the shortest at 2020, for a 24-hour duration solar-powered UAV.</p><br>
10

Model-based design of hybrid electric marine propulsion system using modified low-order ship hull resistance and propeller thrust models

Liu, Siyang 05 January 2021 (has links)
Transportation is a primary pollution source contributing to 14 percent of global greenhouse gas emissions, and 12 percent of transportation emissions came from maritime activities. Emissions from the ferry industry, which carries roughly 2.1 billion passengers and 250 million vehicles annually, is a major concern for the general public due to their near-shore operations. Compared to the rapidly advancing clean automotive propulsion, fuel efficiency and emissions improvements for marine vessels are more urgent and beneficial due to the significantly higher petroleum fuel consumption and heavy pollutants and the relatively slow adoption of clean propulsion technology by the marine industry. Hybrid electric propulsion, proven to be effective for ground vehicles, presents a promising solution for more efficient clean marine transportation. Due to the diversified hull/propulsor design and operation cycle, the development of a hybrid electric marine propulsion system demands model-based design and control optimization for each unique and small batch production vessel. The integrated design and control optimization further require accurate and computation efficient hull resistance and propulsor thrust calculation methods that can be used to predict needed propulsion power and gauge vessel performance, energy efficiency, and emissions. This research focuses on improving the low-order empirical hull resistance and propulsor thrust models in the longitudinal direction by extracting model parameters from one-pass computational fluid dynamics (CFD) simulation and testing the acquired models in integrated design optimization of the marine propulsion system. The model is implemented in MATLAB/Simulink and ANSYS Aqwa and validated using operation data from BC Ferries’ ship Tachek. The modified low-order model (M-LOM) is then used in the integrated optimizations of propulsion system component sizes and operation control strategies for another BC Ferries’ ship, Skeena Queen. The performance, energy efficiency, and emissions of various propulsion options, including nature gas-mechanical and natural gas-electric benchmarks, and hybrid electric alternatives of series hybrid, parallel hybrid, and battery/pure electric are compared to demonstrate the benefits of the new method in completing these complex tasks and hybrid electric marine propulsion. The research forms the foundation for further studies to achieve more accurate propulsion demand prediction and a more comprehensive lifecycle cost assessment of clean marine propulsion solutions. / Graduate

Page generated in 0.0738 seconds