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Articles 31 - 44 of 44
Full-Text Articles in Mechanical Engineering
Decentralized Power Management In Microgrids, Amit Bhattacharjee
Decentralized Power Management In Microgrids, Amit Bhattacharjee
Electronic Theses and Dissertations
A large number of power sources, operational in a microgrid, optimum power sharing and accordingly controlling the power sources along with scheduling loads are the biggest challenges in modern power system. In the era of smart grid, the solution is certainly not simple paralleling. Hence it is required to develop a control scheme that delivers the overall power requirements while also adhering to the power limitations of each source. As the penetration of distributed generators increase and are diversifi ed, the choice of decentralized control becomes preferable. In this work, a decentralized control framework is conceived. The primary approach is …
Decentralized Power Management And Transient Control In Hybrid Fuel Cell Ultra-Capacitor System, Seyed Omid Madani
Decentralized Power Management And Transient Control In Hybrid Fuel Cell Ultra-Capacitor System, Seyed Omid Madani
Electronic Theses and Dissertations
Solid Oxide Fuel Cells (SOFCs) are considered suitable for alternative energy solutions due to advantages such as high efficiency, fuel flexibility, tolerance to impurities, and potential for combined cycle operations. One of the main operating constraints of SOFCs is fuel starvation, which can occur under fluctuating power demands. It leads to voltage loss and detrimental effects on cell integrity and longevity. In addition, reformer based SOFCs require sufficient steam for fuel reforming to avoid carbon deposition and catalyst degradation. Steam to carbon ratio (STCR) is an index indicating availability of the steam in the reformer. This work takes a holistic …
Modeling Repair Patches Of Ship Hull And Studying The Effect Of Their Orientation On Stresses, Halima Enwegy
Modeling Repair Patches Of Ship Hull And Studying The Effect Of Their Orientation On Stresses, Halima Enwegy
Electronic Theses and Dissertations
The hull is the most important structural part of any maritime vessel. It must be adequately designed to withstand the harsh sailing environmental conditions and associated forces. In the past, the basic material used to manufacture the ship hull was wood, where the hull was usually shaped as cylindrical wooden shanks. In the present, hull designs have developed to steel columns or stiffened panels that are made of different types of materials. Panels that are stiffened orthogonally in two or more directions and have nine independent material constants are defined as orthotropic panels, and they achieve high specific strength. This …
Piezospectroscopic Calibration Of Alumina-Nanocomposites For The Development Of Stress-Sensing Structures, Daniela Fugon-Dessources
Piezospectroscopic Calibration Of Alumina-Nanocomposites For The Development Of Stress-Sensing Structures, Daniela Fugon-Dessources
Electronic Theses and Dissertations
Alpha-alumina is known to exhibit photo-luminescent (PL) properties, mainly characteristic R-lines that shift according to applied stress. In addition to showing excellent PL properties, polymers with embedded alumina nanoparticles have been shown to improve the overall composite mechanical properties. While the use of the PL properties to develop stress-sensing materials using an alumina-epoxy material has been success- fully shown in compression, the properties have not been developed for tension. In this study, the PL response of variable volume fraction alumina-epoxy composites will be determined under tensile conditions. It is expected that increasing the volume fraction of alumina nanoparticles will increase …
Synthesis, Processing And Characterization Of Polymer Derived Ceramic Nanocomposite Coating Reinforced With Carbon Nanotube Preforms, Hongjiang Yang
Synthesis, Processing And Characterization Of Polymer Derived Ceramic Nanocomposite Coating Reinforced With Carbon Nanotube Preforms, Hongjiang Yang
Electronic Theses and Dissertations
Ceramics have a number of applications as coating material due to their high hardness, wear and corrosion resistance, and the ability to withstand high temperatures. Critical to the success of these materials is the effective heat transfer through a material to allow for heat diffusion or effective cooling, which is often limited by the low thermal conductivity of many ceramic materials. To meet the challenge of improving the thermal conductivity of ceramics without lowering their performance envelope, carbon nanotubes were selected to improve the mechanical properties and thermal dispersion ability due to its excellent mechanical properties and high thermal conductivity …
Perovskite Catalysts Enhanced Combustion On Porous Media And Thermoelectric Power Conversion, Manuel Robayo
Perovskite Catalysts Enhanced Combustion On Porous Media And Thermoelectric Power Conversion, Manuel Robayo
Electronic Theses and Dissertations
A combustion chamber incorporating a high temperature porous matrix was design and tested. The effects and merits of combining combustion on porous media and catalytic enhancement were explored, in addition to the proof of concept of integrating these technologies with simple heat engines, such as thermoelectric generators, to generate efficient and reliable power. The direct observation of the flame during the combustion becomes possible due to a specially designed stainless steel chamber incorporating a quartz window where the initiation and propagation of the combustion reaction/flame was directly visible. The simple design of the combustion chamber allowed for a series of …
Modeling And Contour Control Of Multi-Axis Linear Driven Machine Tools, Ran Zhao
Modeling And Contour Control Of Multi-Axis Linear Driven Machine Tools, Ran Zhao
Electronic Theses and Dissertations
In modern manufacturing industries, many applications require precision motion control of multi-agent systems, like multi-joint robot arms and multi-axis machine tools. Cutter (end effector) should stay as close as possible to the reference trajectory to ensure the quality of the final products. In conventional computer numerical control (CNC), the control unit of each axis is independently designed to achieve the best individual tracking performance. However, this becomes less effective when dealing with multi-axis contour following tasks because of the lack of coordination among axes. This dissertation studies the control of multi-axis machine tools with focus on reducing the contour error. …
Electric Vehicle Sales And Future Projections, Florida Solar Energy Center, David Block
Electric Vehicle Sales And Future Projections, Florida Solar Energy Center, David Block
FSEC Energy Research Center®
The objective of this research is to evaluate historical vehicle sales as a basis to determine future projections of electric vehicles sales and cumulative values within the U.S. and by selected states. The results for the U.S. show that the cumulative sales of electric vehicles through 2013 is 167,600 vehicles with 96, 700 sold in 2013 or that 58% of total vehicles were sold in 2013. Depending upon the escalation rate selected, the 10 year future U.S. cumulative sales (2023) are predicted to be from 1.8 to 7.3 million vehicles. Future predictions were also done for the states of Florida, …
Mechanical And Thermal Characterization Of Continuous Fiber-Reinforced Pyrolysis-Derived Carbon-Matrix Composites, Donovan Lui
Mechanical And Thermal Characterization Of Continuous Fiber-Reinforced Pyrolysis-Derived Carbon-Matrix Composites, Donovan Lui
Electronic Theses and Dissertations
Maturity of high-temperature polymer-reinforced composites defer to conventionally expensive and intensive methods in both material and manufacturing aspects. Even traditional carbon-carbon, aerogel, and ceramic approaches are highly limited by difficult manufacturing techniques and are subject to sensitive handling throughout their processing and lifetime. Despite their utility in extreme environments, the high costs of existing high-temperature composites find limited practical applicability under high-performance applications. The development of continuous fiber-reinforced pyrolysis-derived carbon-matrix composites aim to circumvent the issues surrounding the manufacturing and handling of conventional high-temperature composites. Polymer matrix composites (PMCs) have a number of attractive properties including light weight, high stiffness-to-weight …
Combustion Instability Mechanism Of A Reacting Jet In Cross Flow At Gas Turbine Operating Conditions, Jared Pent
Combustion Instability Mechanism Of A Reacting Jet In Cross Flow At Gas Turbine Operating Conditions, Jared Pent
Electronic Theses and Dissertations
Modern gas turbine designs often include lean premixed combustion for its emissions benefits; however, this type of combustion process is susceptible to self-excited combustion instabilities that can lead to damaging heat loads and system vibrations. This study focuses on identifying a mechanism of combustion instability of a reacting jet in cross flow, a flow feature that is widely used in the design of gas turbine combustion systems. Experimental results from a related study are used to validate and complement three numerical tools that are applied in this study – self-excited Large Eddy Simulations, 3D thermoacoustic modeling, and 1D instability modeling. …
Response Of Electrified Micro-Jets To Electrohydrodynamic Perturbations, Weiwei Yang
Response Of Electrified Micro-Jets To Electrohydrodynamic Perturbations, Weiwei Yang
Electronic Theses and Dissertations
The breakup of liquid jets is ubiquitous with rich underpinning physics and widespread applications. The natural breakup of liquid jets originates from small ambient perturbations, which can grow exponentially until the amplitude as large as the jet radius is reached. For unelectrified inviscid jets, surface energy analysis shows that only the axisymmetric perturbation is possibly unstable, and this mode is referred as varicose instability. For electrified jets, the presence of surface charge enables additional unstable modes, among which the most common one is the whipping (or kink) instability that bends and stretches the charged jet that is responsible for the …
An Introductory Study Of The Dynamics Of Autorotation For Wind Energy Harvesting, Bilal Salih
An Introductory Study Of The Dynamics Of Autorotation For Wind Energy Harvesting, Bilal Salih
Electronic Theses and Dissertations
Wind turbines have been used for decades to harvest wind energy. They are suitable only to work on close to ground, and have several drawbacks that are related to the availability of the wind and the amount of extracted power compared with the cost of construction. On the other hand, there is an abundant wind power that is available at high altitudes. The wind jet streams at high elevations 8 - 12 kms are pervasive and persistent, and can potentially produce immense wind energy. Even at moderate elevations of 4 - 5 kms, wind power densities are much higher than …
Computational Fluid Dynamics Simulation Of United Launch Alliance Delta Iv Hydrogen Plume Mitigation Strategies, Stephen Guimond
Computational Fluid Dynamics Simulation Of United Launch Alliance Delta Iv Hydrogen Plume Mitigation Strategies, Stephen Guimond
Electronic Theses and Dissertations
During the launch sequence of the United Launch Alliance Delta IV launch vehicle, large amounts of pure hydrogen are introduced into the launch table and ignited by Radial-Outward-Firing-Igniters (ROFIs). This ignition results in a significant flame, or plume, that rises upwards out of the launch table due to buoyancy. The presence of the plume causes increased and unwanted heat loads on the surface of the vehicle. A proposed solution is to add a series of fans and structures to the existing launch table configuration that are designed to inject ambient air in the immediate vicinity of the launch vehicle's nozzles …
Development Of Full Surface Transient Thermochromic Liquid Crystal Technique For Internal Cooling Channels, Lucky Tran
Development Of Full Surface Transient Thermochromic Liquid Crystal Technique For Internal Cooling Channels, Lucky Tran
Electronic Theses and Dissertations
Proper design of high performance industrial heat transfer equipment relies on accurate knowledge and prediction of the thermal boundary conditions. In order to enhance the overall gas turbine efficiency, advancements in cooling technology for gas turbines and related applications are continuously investigated to increase the turbine inlet temperature without compromising the durability of the materials used. For detailed design, local distributions are needed in addition to bulk quantities. Detailed local distributions require advanced experimental techniques whereas they are readily available using numerical tools. Numerical predictions using a computational fluid dynamics approach with popular turbulence models are benchmarked against a semi-empirical …