Mechanical Engineering Commons^™

Bio-Inspired, Varying Manifold Based Method With Enhanced Initial Guess Strategies For Single Vehicle's Optimal Trajectory Planning, Ni Li

Electronic Theses and Dissertations

Trajectory planning is important in many applications involving unmanned aerial vehicles, underwater vehicles, spacecraft, and industrial manipulators. It is still a challenging task to rapidly find an optimal trajectory while taking into account dynamic and environmental constraints. In this dissertation, a unified, varying manifold based optimal trajectory planning method inspired by several predator-prey relationships is investigated to tackle this challenging problem. Biological species, such as hoverflies, ants, and bats, have developed many efficient hunting strategies. It is hypothesized that these types of predators only move along paths in a carefully selected manifold based on the prey’s motion in some of …

Investigation Of Multiscale Fluid Structure Interaction Modeling Of Flow In Arterial Systems, Sebastian Sotelo

Electronic Theses and Dissertations

The study of hemodynamic patterns in large blood vessels, such as the ascending aortic artery, brachiocephalic trunk, right carotid artery and right subclavian artery presents the challenging complexity of vessel wall compliance induced by the high levels of shear stress gradients and blood flow pulsatility. Accurate prediction of hemodynamics in such conditions requires a complete Fluid Structure Interaction (FSI) analysis that couples the fluid flow behavior throughout the cardiac cycle with the structural response of the vessel walls. This research focuses on the computational study of a Multiscale Fluid-Structure Interaction on the arterial wall by coupling Finite Volumes Method (FVM) …

Experimental And Numerical Investigation Of Aerodynamic Unsteadiness In A Gas Turbine Midframe, Matthew Golsen

Electronic Theses and Dissertations

As modern gas turbines implement more and more complex geometry to increase life and efficiency, attention to unsteady aerodynamic behavior becomes more important. Computational optimization schemes are contributing to advanced geometries in order to reduce aerodynamic losses and increase the life of components. These advanced geometries are less representative of cylinder and backward facing steps which have been used as analogous geometries for most aerodynamic unsteadiness research. One region which contains a high degree of flow unsteadiness and a direct influence on engine performance is that of the MidFrame. The MidFrame (or combustor-diffuser system) is the region encompassing the main …

Creep-Fatigue Crack Initiation And Propagation Of A Notched Stainless Steel, Scott Keller

Electronic Theses and Dissertations

Premature failures of vital gas turbine components, such as blades and vanes, have been the result of increasing demands of power generation facilities. As power needs fluctuate throughout the day, operators are quickly firing up gas turbines as a means of providing instant power. Traditionally, these engines run at constant operating conditions; however, contemporary operating conditions call for these engines to be applied on an “as necessary” basis. The result of the cyclic startup and shutdown of gas turbines has led to a phenomenon known as creep-fatigue (CF). A coupling of two primary failure mechanisms in gas turbines, CF conditions …

Nano-Particles In Multi-Scale Composites And Ballistic Applications, Jason Gibson

Electronic Theses and Dissertations

Carbon nanotubes, graphene and nano sized core shell rubber particles have all been extensively researched for their capability to improve mechanical properties of thermoset resins. However, there has been a lack of research on their evaluation for energy absorption in high velocity impact scenarios, and the fundamental mechanics of their failure mechanisms during highly dynamic stress transfer through the matrix. This fundamental research is essential for laying the foundation for improvement in ballistic performance in composite armor. In hard armor applications, energy absorption is largely accomplished through delamination between plies of the composite laminate. This energy absorption is accomplished through …

Computational Fluid Dynamics Investigation Of The Orientation Of A Pediatric Left Ventricle Assist Device Cannula To Reduce Stroke Events, Stephen Guimond

HIM 1990-2015

Ventricle Assist Devices (VADs), which are typically either axial or centrifugal flow pumps implanted on the aortic arch, have been used to support patients who are awaiting cardiac transplantation. Success of the apparatus in the short term has led to long term use. Despite anticoagulation measures, blood clots (thrombi) have been known to form in the device itself or inside of the heart. The Ventricle Assist Devices supply blood flow via a conduit (cannula) implanted on the ascending aorta. Currently, the implantation angle of the VAD cannula is not taken into consideration. Since the VADs supply a significant amount of …

Cost Effectiveness Of Home Energy Retrofits In Pre-Code Vintage Homes In The United States, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

This study investigates the cost effectiveness of a large number of potential home energy retrofit measures using pre-code home archetypes that can be considered typical in a range of climates throughout the United States.

Managing The Drivers Of Airflow And Water Vapor Transport In Existing Single-Family Homes (Revised), Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Air and water vapor are transported into and within single-family homes as a result of pathways and driving forces. Without pathways, no air or water vapor transport could occur. Likewise, without driving forces, little or no air or water vapor transport will occur. Homes always have pathways and driving forces. This report focuses on managing the driving forces that move air and water vapor across the building envelope.

A Comparison Of Homes Built To The 2009 And 1984 Florida Energy Codes, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

The Florida Solar Energy Center conducted research into the effectiveness of the Florida energy code to reduce energy use in residential buildings. FSEC examined two groups of homes: those built to the 1984 energy code (June 1,1984-1985) and those built to the 2007 with 2009 supplement energy code (March 1, 2009-2010). This report discusses data collection methods, analysis and results that focus on comparisons of measured energy use and house characteristics between both code periods.

Measured Performance Of Occupied, Side-By-Side, South Texas Homes, Florida Solar Energy Center, Dave Chasar

FSEC Energy Research Center®

The performance of three occupied homes built in 2009 in San Antonio, Texas with identical floor plans and orientation were evaluated through a partnership between the Florida Solar Energy Center, CPS Energy, and Woodside Homes of South Texas. Measurements included whole-house gas and electricity use as well as heating, cooling, hot water, major appliances, and indoor and outdoor conditions. One home built to the builder's standard practice served as the control; the other homes demonstrated high performance features.

The goals of this research were to: (1) learn how energy systems affect peak load profiles during the hottest weather conditions; (2) …

Accuracy Of The Home Energy Saver Energy Calculation Methodology, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The Home Energy Saver (HES) suite offers popular online simulation tools that enable U.S. homeowners and energy professionals to rigorously evaluate home energy use and develop recommendations on how energy can be saved across all end uses. The underlying analytical system is also available as a web service to power third-party energy analysis tools. Given the system's diverse uses, it is important that the simulation is robust and intrinsically accurate. While the engineering methods and assumptions are extensively documented and subjected to peer review, it is useful to evaluate how well HES predicts energy use in occupied homes. In this …

Side-By-Side Testing Of Water Heating Systems: Results From The 2010-2011 Evaluation, Florida Solar Energy Center, Carlos Colon

FSEC Energy Research Center®

REVISED MARCH 2013 The Building America (BAPIRC) team at FSEC has released a report containing results from a second testing rotation (Phase II) on seven hot water systems evaluated side-by side. Results show the seasonal performance variation and compares solar systems against electric resistance and the Heat Pump Water Heater (HPWH). Standard and tankless natural gas were also evaluated, where the latter demonstrated a 24% natural gas reduction. The lowest averaged electric power consumptions were demonstrated by the HPWH (2.75 kWh/day) and the PV-pumped solar water heater (3.03 kWh/day). Other testing performed on the HPWH under conditioned and restricted air …

Final Technical Report (2nd Revision) Arra: Florida Energy Code Compliance Train-The-Trainer Program, Florida Solar Energy Center, Jeffrey Sonne

FSEC Energy Research Center®

A multi-faceted Florida Energy Code compliance methods, tools and field verification training program was established that included development of two instructor-led and two web-based courses, instructor training and course development support, and training of building officials and contractors throughout the state.

Separate instructor-led commercial and residential 2010 Florida Energy Code compliance courses were developed for train-the-trainer class use, and existing instructor-led blueprints data collection and energy code software courses were redeveloped as web-based courses.

Through partnerships with Florida colleges, building departments and industry organizations, a total of 42 instructors were trained to provide commercial energy code compliance training and 42 …

Final Report Of Task Eight: Arra Energy Code Compliance Project, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

This report summarizes the Florida energy code compliance project for both residential and commercial activities and shows results in accomplishing the Florida Energy Code compliance objectives to develop and conduct an energy code enforcement study. Work is discussed regarding efforts to find and conduct Florida Energy Code enforcement practice evaluations in residential and commercial buildings built after the March 1, 2009 code period.

Adding Cerebral Autoregulation To A Lumped Parameter Model Of Blood Flow, Russell Gentile

HIM 1990-2015

A mathematical model of blood flow in infants with hypoplastic left heart syndrome (HLHS) was improved by adding cerebral autoregulation. This is the process by which blood vessels constrict or dilate to keep blood flow steady in certain organs during pressure changes. The original lumped parameter model transformed the fluid flow into an electrical circuit. Its behavior is described using a system of thirty-three coupled differential equations that are solved numerically using a fourth-order Runge-Kutta method implemented in MATLAB. A literature review that includes a discussion of autoregulation mechanisms and approaches to modeling them is followed by a description of …

Partnership For High Performance Housing Final Report, Florida Solar Energy Center, Janet Mcilvaine

FSEC Energy Research Center®

This report describes research conducted by the Florida Solar Energy Center (FSEC) under funding from the Pacific Northwest National Laboratory. This work falls under the umbrella of the U.S. Department of Energy's Building America program. High performance goals were set for renovation of existing housing and construction of new affordable housing. Both efforts included monitoring the energy use of several homes.

Creating Performance Curves For Variable Refrigerant Flow Heat Pumps In Energyplus, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

This document describes methods to generate performance curve coefficients for variable refrigerant flow heat pumps in DOE's EnergyPlus building energy simulation program. Manufactures performance data for capacity and power are used to create full-load and part-load performance curves for cooling and heating operating modes. When performance variations for full-load capacity or power cannot be modeled using a single performance curve, the data set is divided into lower and upper temperature regions and dual performance curves are used. Table objects may also be created to substitute when performance curves do not provide the required accuracy. These performance curves or tables are …

Flexible Residential Test Facility Instrumentation Plan, Florida Solar Energy Center, Robin Vieira

FSEC Energy Research Center®

This report provides the status of the instrumentation and a test plan for the facility. As this is the first Building America (BA) report on the facility, a description of the design and construction is included as well.

Achieving Very High Efficiency And Net Zero Energy In An Existing Home In A Hot-Humid Climate: Long-Term Utility And Monitoring Data, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

This study summarizes the first six months of detailed data collected about a single-family home that experienced a series of retrofits targeting reductions in energy use. The project was designed to develop data about how envelope modifications in heating, ventilation, and air conditioning and domestic hot water and renewable measures can result in considerable energy reductions and potentially net zero energy for an existing home. Using utility billing records and recent detailed monitoring data, this study was also able to chronicle the progress of energy reduction over a 22-year period.

Laser Spark Ignition Of Counter-Flow Diffusion Flames: Effects Of Diluents And Diffusive-Thermal Properties, Fidelio Sime Segura

Electronic Theses and Dissertations

A pulsed Nd:YAG laser is used to study laser spark ignition of methane counter-flow diffusion flames with the use of helium and argon as diluents to achieve a wide range of variations in transport properties. The global strain rate and Damkohler number on successful ignition were investigated for the effects of Lewis number and transport properties, which are dependent on the diluent type and dilution level. A high-speed camera is used to record the ignition events and a software is used for pre-ignition flow field and mixing calculations. It is found that the role of effective Lewis number on the …

Numerical Simulation Of Electrolyte-Supported Planar Button Solid Oxide Fuel Cell, Amjad Aman

Electronic Theses and Dissertations

Solid Oxide Fuel Cells are fuel cells that operate at high temperatures usually in the range of 600oC to 1000oC and employ solid ceramics as the electrolyte. In Solid Oxide Fuel Cells oxygen ions (O2- ) are the ionic charge carriers. Solid Oxide Fuel Cells are known for their higher electrical efficiency of about 50-60% [1] compared to other types of fuel cells and are considered very suitable in stationary power generation applications. It is very important to study the effects of different parameters on the performance of Solid Oxide Fuel Cells and for this purpose the experimental or numerical …

Fire Retardant Polymer Nanocomposites: Materials Design And Thermal Degradation Modeling, Jinfeng Zhuge

Electronic Theses and Dissertations

Compared to conventional materials, polymer matrix composites (PMCs) have a number of attractive properties, including light weight, easiness of installation, potential to lower system-level cost, high overall durability, and less susceptibility to environmental deterioration. However, PMCs are vulnerable to fire such that they degrade, decompose, and sometimes yield toxic gases at high temperature. The degradation and decomposition of composites lead to loss in mass, resulting in loss in mechanical strength. This research aims to improve the structural integrity of the PMCs under fire conditions by designing and optimizing a fire retardant nanopaper coating, and to fundamentally understand the thermal response …

Optimization Of Ocean Thermal Energy Conversion Power Plants, Steven Emanoel Rizea

Electronic Theses and Dissertations

A proprietary Ocean Thermal Energy Conversion (OTEC) modeling tool, the Makai OTEC Thermodynamic and Economic Model (MOTEM), is leveraged to evaluate the accuracy of finite-time thermodynamic OTEC optimization methods. MOTEM is a full OTEC system simulator capable of evaluating the effects of variation in heat exchanger operating temperatures and seawater flow rates. The evaluation is based on a comparison of the net power output of an OTEC plant with a fixed configuration. Select optimization methods from the literature are shown to produce between 93% and 99% of the maximum possible amount of power, depending on the selection of heat exchanger …

Virtual Motion Camouflage Based Nonlinear Constrained Optimal Trajectory Design Method, Gareth Basset

Electronic Theses and Dissertations

Nonlinear constrained optimal trajectory control is an important and fundamental area of research that continues to advance in numerous fields. Many attempts have been made to present new methods that can solve for optimal trajectories more efficiently or to improve the overall performance of existing techniques. This research presents a recently developed bio-inspired method called the Virtual Motion Camouflage (VMC) method that offers a means of quickly finding, within a defined but varying search space, the optimal trajectory that is equal or close to the optimal solution. The research starts with the polynomial-based VMC method, which works within a search …

Characterization Of Dynamic And Static Mechanical Behavior Of Polyetherimide, Nathan J. Mutter

Electronic Theses and Dissertations

Polymers are increasingly being used in engineering designs due to their favorable mechanical properties such as high specific strength, corrosive resistance, manufacturing flexibility. The understanding of the mechanical behavior of these polymers under both static and dynamic loading is critical for their optimal implementation in engineering applications. One such polymer utilized in a wide variety of applications from medical instrumentation to munitions is Polyetherimide, referred to as Ultem. This thesis characterizes both the static and dynamic mechanical behavior of Ultem 1000 through experimental methods and numerical simulations. Standard compression experiments were conducted on and MTS test frame to characterize the …

Simulation Of Heat/Mass Transfer Of A Three-Layer Impingement/Effusion Cooling System, Brandon Smith

Electronic Theses and Dissertations

Cooling techniques for high density electrical components and electronic devices have been studied heavily in recent years. The advancements in the electrical/electronic industry have required methods of high heat flux removal. Many of the current electrical components and electronic devices produce a range of heat fluxes from 20 W/cm2 – 100 W/cm2 . While parallel flow cooling systems have been used in the past, jet impingement is now more desirable for its potential to have a heat transfer coefficient 3-5 times greater than that of parallel flow at the same flow rate. Problems do arise when the jet impingement is …

Re, Os, Al And Mg Boron Rich Ceramic Compounds For Structural Application, Zhilin Xie

Electronic Theses and Dissertations

Hard and ultra-incompressible materials are of great interest due to their important applications in industry. A common route to design hard materials is combining transition metals with light and small covalent elements. Light elements such as carbon, oxygen, nitrogen and boron have been considered as good candidates. This study includes the synthesis of ReB2, OsB2 and another higher boride AlMgB14. Most of the techniques used for ReB2 synthesis reported 1:2.5 Re to B ratio because of the loss of the B during high temperature synthesis. However, as a result of B excess, the amorphous boron, located along the grain boundaries …

Simulation Of A Capacitive Micromachined Ultrasonic Transducer With A Parylene Membrane And Graphene Electrodes, David Sadat

Electronic Theses and Dissertations

Medical ultrasound technology accounts for over half of all imaging tests performed worldwide. In comparison to other methods, ultrasonic imaging is more portable and lower cost, and is becoming more accessible to remote regions where traditionally no medical imaging can be done. However, conventional ultrasonic imaging systems still rely on expensive PZT-based ultrasound probes that limit broader applications. In addition, the resolution of PZT based transducers is low due to the limitation in hand-fabrication methods of the piezoelectric ceramics. Capacitive Micromachined Ultrasonic Transducers (CMUTs) appears as an alternative to the piezoelectric (PZT) ceramic based transducer for ultrasound medical imaging. CMUTs …

Experimental Study And Modeling Of Mechanical Micro-Machining Of Particle Reinforced Heterogeneous Materials, Jian Liu

Electronic Theses and Dissertations

This study focuses on developing explicit analytical and numerical process models for mechanical micro-machining of heterogeneous materials. These models are used to select suitable process parameters for preparing and micro-machining of these advanced materials. The material system studied in this research is Magnesium Metal Matrix Composites (Mg-MMCs) reinforced with nano-sized and micro-sized silicon carbide (SiC) particles. This research is motivated by increasing demands of miniaturized components with high mechanical performance in various industries. Mg-MMCs become one of the best candidates due to its light weight, high strength, and high creep/wear resistance. However, the improved strength and abrasive nature of the …

Aerodynamic Characteristics Of A Gas Turbine Exhaust Diffuser With An Accompanying Exhaust Collection System, Bryan Bernier

Electronic Theses and Dissertations

The effects of an industrial gas turbine’s Exhaust Collector Box (ECB) geometry on static pressure recovery and total pressure loss were investigated in this study experimentally and computationally. This study aims to further understand how exit boundary conditions affect the performance of a diffuser system as well as the accuracy of industry standard computational models. A design of experiments approach was taken using a Box-Behnken design method for investigating three geometric parameters of the ECB. In this investigation, the exhaust diffuser remained constant through each test, with only the ECB being varied. A system performance analysis was conducted for each …