Mechanical Engineering Commons^™

Microscopic Surface Textures Created By Interfacial Flow Instabilities, Jing Gu

HIM 1990-2015

In nature, microscopic surface textures impact useful function, such as the drag reduction of shark skin (Dean & Bhushan, 2010) and superhydrophobicity of the lotus leaf(Pan, Kota, Mabry, & Tuteja, 2013). In this study, we explore these phenomena by re-creating microscopic surface textures via the method of interfacial flow instability in drying polyvinylidene fluoride (PVDF) acetone solutions. In general, PVDF films can be made using either spin coating or electrospray deposition with various weight concentrations in acetone. In order to study the morphology of the porous structure of PVDF films, wet deposition samples were fabricated by spin coating or near-field …

The Next Step Toward Widespread Residential Deep Energy Retrofits, Florida Solar Energy Center, Janet Mcilvaine

FSEC Energy Research Center®

The Building America Partnership for Improved Residential Construction (BA-PIRC) has been working with affordable housing entities to identify cost-effective technical pathways to achieve energy savings levels of 30% and safeguard or enhance indoor air quality (IAQ), durability, and comfort (McIlvaine et al. 2012; Fairey and Parker 2012).

Determining Appropriate Heating And Cooling Thermostat Set Points For Building Energy Simulations For Residential Buildings In North America, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Existing building energy simulation tools have a purported tendency to over-predict heating use and, in some cases, to under-predict cooling use, an outcome often attributed to inappropriate assumptions about thermostat management. As a result, a systematic review was conducted for the purposes of determining typical heating and cooling set points for single-family houses in North America. The preliminary consensus results provide an empirical basis for establishing typical inputs for building energy simulation models, increasing prediction accuracy of heating and cooling loads. The results of this review have been applied as default values in the Lawrence Berkeley National Laboratory's Home Energy …

A Computed Tomography-Based Model Of The Infant Hip Anatomy For Dynamic Finite Element Analysis Of Hip Dysplasia Biomechanics, Kyle Snethen

HIM 1990-2015

Newborns diagnosed with hip dysplasia face severe consequences when treatments fail. The Pavlik harness presents the most common worldwide treatment for correcting this medical hip abnormality in newborns, but becomes increasingly ineffective as subluxation increases. A dynamic finite element analysis on the hip joint would yield results that could provide insight to physicians as to how the Pavlik harness could be optimized to increase its success rate and develop patient-specific treatment plans. The study completes the first step in such an analysis by generating a three-dimensional model of an infant hip joint directly derived from computed tomography imaging in order …

Production, Control And Actuation Of Micron-Sized Particles In A Microfluidic T-Junction, James Wilson

HIM 1990-2015

This research is directed towards understanding the mechanisms associated with the manufacture of solid microspheres less than 100 [micrometers], from liquid droplets with nanosuspensions in a microfluidic T-junction, which are heated downstream of the channel. Preliminary material characterization tests on colloidal suspensions of alumina and copper oxide demonstrate promising temperature dependent viscosity results indicating solidification in the temperature range of 40°C-50°C. The solidification mechanism is referred to as Temperature Induced Forming and is described by polymeric bridges formed between nanoparticles in suspension at elevated temperatures, resulting in a solid structure. The polymer network results from the ionization of alumina at …

Efficient Multifamily Homes In A Hot-Humid Climate By Atlantic Housing Partners, Florida Solar Energy Center, Dave Chasar

FSEC Energy Research Center®

With assistance from the Florida Solar Energy Center (FSEC) and its Building America Partnership for Improved Residential Construction (BA-PIRC), Atlantic Housing Partners (AHP) has implemented a high performance, systems-engineered package of measures in the new construction multifamily housing sector in the hot-humid climate zone. This report demonstrates how the initiative achieves Building America (BA) goals of 30%-50% energy savings. In addition, the report discusses the role of utility allowance calculations, used as part of the low-income housing tax credit process, to value those energy savings.

Results of energy modeling are presented to demonstrate that the specification package achieves 40% energy …

Approaches To 30% Energy Savings At The Community Scale In The Hot-Humid Climate, Florida Solar Energy Center, Stephanie Thomas-Rees

FSEC Energy Research Center®

The Building America Partnership for Improved Residential Construction, formerly the Building America Industrialized Housing Partnership, has worked with several community-scale builders within the hot-humid climate zone to improve performance of production-, or community-scale, housing. Tommy Williams Homes (Gainesville, Florida), LifeStyle Homes (Melbourne, Florida), and Habitat for Humanity (various locations, Florida) have all been continuous partners of the Building America Program. The activities of these partners, described in this report, achieved the Building America goal of 30% whole-house source energy savings using packages adopted at the community scale. For new homes, the reference case is the B10 Benchmark, aligned with 2009 …

Energy Retrofit Field Study And Best Practices In A Hot-Humid Climate, Florida Solar Energy Center, Janet Mcilvaine

FSEC Energy Research Center®

In the U.S. Census Bureau's Southern region, housing starts ranged from 4.6 to 5.9 million per decade from the 1970s through the 2000s, nearly twice as many as any other region across all decades. The potential for energy savings in these homes is vast, perhaps our most available untapped resource for reducing energy needs. This study was conducted in central Florida, which forms part of the Census Bureau's Southern region. It examines efficiency retrofit opportunities, typical renovation practices, and pathways for achieving U.S. Department of Energy (DOE) goals for existing homes in that region.

Analysis Of Hers Index Scores For Recent Versions Of The International Energy Conservation Code (Iecc) [Revised], Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

The EnergyGauge HERS software tool was used to examine the IECC Standard Reference Design (IECC SRD) configuration for one-story 2000 ft2 and two-story 2,400 ft2 single-family homes in sixteen representative U.S. cities. IECC SRD homes were configured for the 2006 IECC, the 2009 IECC and the 2012 IECC. Two additional set of analysis were conducted, both using the 2012 IECC SRD with enhanced equipment: 1) with equipment configured to meet the 2015 National Appliance Energy Conservation Act (NAECA) equipment requirements and 2) with equipment that is on the cusp of significant market penetration with efficiencies greater than the 2015 standard.HERS …

Short-Term Test Results: Transitional Housing Energy Efficiency Retrofit In The Hot-Humid Climate, Florida Solar Energy Center, Karen Sutherland

FSEC Energy Research Center®

This project evaluates the renovation of a 5,800-ft², multiuse facility located in St. Petersburg, on the west coast of central Florida, in the hot-humid climate. An optimal package of retrofit measures was designed to deliver 30%-40% annual energy cost savings for this building with annual utility bills exceeding $16,000 and high base load consumption. Researchers projected energy cost savings for potential retrofit measures based on pre-retrofit findings and disaggregated, weather-normalized utility data. A cost-benefit analysis was conducted for the seven retrofit measures implemented; adding attic insulation and sealing soffits, tinting windows, improving whole-building airtightness, upgrading heating and cooling …

Measured Cooling Performance And Potential For Buried Duct Condensation In A 1991 Central Florida Retrofit Home, Florida Solar Energy Center, Dave Chasar

FSEC Energy Research Center®

The Florida Solar Energy Center (FSEC) conducted energy performance monitoring of two existing residences in Central Florida that were undergoing various retrofits. These homes were occupied by FSEC researchers and were fully instrumented to yield detailed energy, temperature, and humidity measurements. The data gave feedback about the performance of two levels of retrofit in two types of homes in a hot-humid climate. This report covers a moderate-level retrofit and includes 2 years of pre-retrofit data to characterize the impact of improvements. The other home, covered in a separate report (Parker and Sherwin 2012), is a deep energy retrofit that has …

Combustion Synthesis And Characterization Of Porous Niti Intermetallic For Structural Application, Jessica Vanterpool

Electronic Theses and Dissertations

This thesis describes experimental investigation of thermal and combustion phenomena as well as structure for self- propagating combustion synthesis of porous Ni - Ti intermetallic aimed for structural biomedical application. The control parameters for the porosity distribution have been investigated experimentally through varying the preheat temperature, initial porosity, initial elemental particle size, and applied pressure during the fabrication process. Ni and Ti elemental powders are mixed using a 1:1 ratio. The mixture is compressed using several different compression forces to produce cylindrical samples of 1.1 cm diameter and 2-3cm length, with initial porosity ranging from 30% to 40%. The samples …

Low Strain Rate Studies Of Alumina Epoxy Composites Using Piezospectroscopy, Ashley Jones

Electronic Theses and Dissertations

Particulate composites are widely used in many aerospace and military applications as energetic materials, armor materials or coatings and their behavior under dynamic loads have gained increasing significance. The addition of modifiers such as alumina nanoparticles generally facilitates the improvement of the mechanical strength to density ratio due to high specific area and particle rigidity. This allows for sufficient particlematrix bonding and therefore improved stiffness and load transfer in the composite. Photo-luminescent α-alumina nanoparticles when embedded in an epoxy matrix allow for the added benefit of in situ measurements at low strain rates to provide stress-sensitive information using the particle …

Electrohydrodynamic Manipulation Of Liquid Droplet Emulsions In A Microfluidic Channel, Jonathan Wehking

Electronic Theses and Dissertations

This work specifically aims to provide a fundamental framework, with some experimental validation, for understanding droplet emulsion dynamics in a microfluidic channel with an applied electric field. Electrification of fluids can result in several different modes of electrohydrodynamics (EHD). Several studies to date have provided theoretical, experimental, and numerical results for stationary droplet deformations and some flowing droplet configurations, but none have reported a method by which droplets of different diameters can be separated, binned and routed through the use of electric fields. It is therefore the goal of this work to fill that void and report a comprehensive understanding …

Planning And Control Of Swarm Motion As Continua, Hossein Rastgoftar

Electronic Theses and Dissertations

In this thesis, new algorithms for formation control of multi agent systems (MAS) based on continuum mechanics principles will be investigated. For this purpose agents of the MAS are treated as particles in a continuum, evolving in an n-D space, whose desired configuration is required to satisfy an admissible deformation function. Considered is a specific class of mappings that is called homogenous where the Jacobian of the mapping is only a function of time and is not spatially varying. The primary objectives of this thesis are to develop the necessary theory and its validation via simulation on a mobile-agent based …

Generation And Printing Of Strictly Monodisperse Droplets, Hongxu Duan

Electronic Theses and Dissertations

Highly monodisperse droplets are attracting great attention both in many research areas, such as aerosol science, combustion, and Nano-manufacturing. This thesis invents a novel aerosol generator: “Periodic Electro Hydro-dynamic Chopper” termed as “PEHD chopper”, and develops a new method to directly print micro-patterns with monodisperse droplets. The principle of the PEHD chopper is to use the fringe electric field of a capacitor to introduce controlled perturbation on a liquid jet. We first derived the governing equations for a circular inviscid liquid jet under transverse electric fields. The electric fields were obtained through numerical simulation. Then we used a high speed …

Experimental Investigation Of Breakup And Coalescence Characteristics Of A Hollow Cone Swirling Spray, Joshua Lee

Electronic Theses and Dissertations

Atomization can be achieved by discharging liquid at relative high velocities into a slow moving environment (hydraulic nozzles) or by discharging liquid at low velocities into a fast moving gas flow (air-blast nozzles). These two types of injector nozzles are featured in majority of the industry applications such as power generation, food or pharmaceutical powder formation, spray painting, petroleum refining, and thermal sprays. The most common atomizer used in combustion engines is the pressure-swirl nozzle (Simplex nozzle) to obtain a homogenous mixture at different equivalence ratios. The experimental studies performed with pressure-swirl nozzles have reported contradictory results over the last …

A Linear Multiplexed Electrospray Thin Film Deposition System, Brandon Lojewski

Electronic Theses and Dissertations

Liquid spray is essential to industries requiring processes such as spray coating, spray drying, spray pyrolysis, or spray cooling. This thesis reports the design, fabrication, and characterization of a thin film deposition system which utilizes a linear multiplexed electrospray (LINES) atomizer. First, a thorough review of the advantages and limitations of prior multiplexed electrospray systems leads to discussion of the design rationale for this work. Next, the line of charge model was extended to prescribe the operating conditions for the experiments and to estimate the spray profile. The spray profile was then simulated using a Lagrangian model and solved using …

Heat And Fluid Flow Characterization Of A Single-Hole-Per-Row Impingement Channel At Multiple Impingement Heights, Roberto Claretti

Electronic Theses and Dissertations

The present work studies the relationship between target and sidewall surfaces of a multirow, narrow impingement channel at various jet heights with one impingement hole per row. Temperature sensitive paint and constant flux heaters are used to gather heat transfer data on the target and side walls. Jet-to-target distance is set to 1, 2, 3, 5, 7 and 9 jet diameters. The channel width is 4 jet diameters and the jet stream wise spacing is 5 jet diameters. All cases were run at Reynolds numbers ranging from 5,000 to 30,000. Pressure data is also gathered and used to calculate the …

Thermomechanical Fatigue Life Prediction Of Notched 304 Stainless Steel, Justin Karl

Electronic Theses and Dissertations

The behavior of materials as they are subjected to combined thermal and mechanical fatigue loads is an area of research that carries great significance in a number of engineering applications. Power generation, petrochemical, and aerospace industries operate machinery with expensive components that undergo repeated applications of force while simultaneously being exposed to variable temperature working fluids. A case of considerable importance is found in steam turbines, which subject blades to cyclic loads from rotation as well as the passing of heated gases. The complex strain and temperature histories from this type of operation, combined with the geometric profile of the …

The Characterization Of The Effects Of Stress Concentrations On The Mechanical Behavior Of A Micronic Woven Wire Mesh, Steven Kraft

Electronic Theses and Dissertations

Woven structures are steadily emerging as excellent reinforcing components in dualphase composite materials subjected to multiaxial loads, thermal shock, and aggressive reactants in the environment. Metallic woven wire mesh materials display good ductility and relatively high specific strength and specific resilience. While use of this class of materials is rapidly expanding, significant gaps in mechanical behavior classification remain. This thesis works to address the mechanics of material knowledge gap that exists for characterizing the behavior of a metallic woven structure, composed of stainless steel wires on the order of 25 microns in diameter, and subjected to various loading conditions and …

On Radar Deception, As Motivation For Control Of Constrained Systems, Hadi Hajieghrary

Electronic Theses and Dissertations

This thesis studies the control algorithms used by a team of ECAVs (Electronic Combat Air Vehicle) to deceive a network of radars to detect a phantom track. Each ECAV has the electronic capability of intercepting the radar waves, and introducing an appropriate time delay before transmitting it back, and deceiving the radar into seeing a spurious target beyond its actual position. On the other hand, to avoid the errors and increase the reliability, have a complete coverage in various atmosphere conditions, and confronting the effort of the belligerent intruders to delude the sentinel and enter the area usually a network …

A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart

Electronic Theses and Dissertations

In the combustion zone of industrial- and aero- gas turbines, thermomechanical fatigue (TMF) is the dominant damage mechanism. Thermomechanical fatigue is a coupling of independent creep, fatigue, and oxidation damage mechanisms that interact and accelerate microstructural degradation. A mixture of intergranular cracking due to creep, transgranular cracking due to fatigue, and surface embrittlement due to oxidation is often observed in gas turbine components removed from service. The current maintenance scheme for gas turbines is to remove components from service when any criteria (elongation, stress-rupture, crack length, etc.) exceed the designed maximum allowable. Experimental, theoretical, and numerical analyses are performed to …

Biomechanical Factors Influencing Treatment Of Developmental Dysplasia Of The Hip (Ddh) With The Pavlik Harness, Orlando Ardila

Electronic Theses and Dissertations

Biomechanical factors influencing the reduction of dislocated hips with the Pavlik harness in patients of Developmental Dysplasia of the Hip (DDH) were studied using a simplified three-dimensional computer model simulating hip reduction dynamics in (1) subluxated, and (2) fully dislocated hip joints. The CT-scans of a 6 month-old female infant were used to measure the geometrical features of the hip joint including acetabular and femoral head diameter, acetabular depth, and geometry of the acetabular labrum, using the medical segmentation software Mimics. The lower extremity was modeled by three segments: thigh, leg, and foot. The mass and the location of the …

Manufacturing Of Single Solid Oxide Fuel Cells, Jonathan Torres-Caceres

Electronic Theses and Dissertations

Solid oxide fuel cells (SOFCs) are devices that convert chemical energy into electrical energy and have the potential to become a reliable renewable energy source that can be used on a large scale. SOFCs have 3 main components; the electrolyte, the anode, and the cathode. Typically, SOFCs work by reducing oxygen at the cathode into O2- ions which are then transported via the electrolyte to the anode to combine with a fuel such as hydrogen to produce electricity. Research into better materials and manufacturing methods is necessary to reduce costs and improve efficiency to make the technology commercially viable. The …

Automated Hybrid Singularity Superposition And Anchored Grid Pattern Bem Algorithm For The Solution Of The Inverse Geometric Problem, Marcus Ni

Electronic Theses and Dissertations

A method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a first step, clusters of singularities are utilized to solve the inverse problem and to identify the location of the centroid(s) of the subsurface cavity(ies)/flaw(s). In a second step, the reconstruction of …

Transient Multi-Scale Computational Fluid Dynamics (Cfd) Model For Thrombus Tracking In An Assit Device Vascular Bed, Ruben Osorio

Electronic Theses and Dissertations

Heart failure occurs when the heart is not capable to pump blood at a sufficient rate to meet the demands of the body. Depending on the health of the heart, doctors may recommend a heart transplant, but finding a suitable donor is often a long duration process and the patient might be at an advance condition or the patient is not adequate for a heart transplant. In such cases Ventricular assist devices (VAD) are implemented. The purpose of a VAD is to aid the heart to pump the correct amount of blood, by doing so it relives the load that …

Thermoacoustic Riemann Solver Finite Volume Method With Application To Turbulent Premixed Gas Turbine Combustion Instability, Perry Johnson

Electronic Theses and Dissertations

This thesis describes the development, verification, and validation of a three dimensional time domain thermoacoustic solver. The purpose of the solver is to predict the frequencies, modeshapes, linear growth rates, and limit cycle amplitudes for combustion instability modes in gas turbine combustion chambers. The linearized Euler equations with nonlinear heat release source terms are solved using the finite volume method. The treatment of mean density gradients was found to be vital to the success of frequency and modeshape predictions due to the sharp density gradients that occur across deflagration waves. In order to treat mean density gradients with physical fidelity, …

Study Of Transport Phenomena In Carbon-Based Materials, Walid Aboelsoud

Electronic Theses and Dissertations

In air-cooled heat exchangers, air-side thermal resistance is usually the largest compared to conduction and liquid-side thermal resistances. Thus, reducing the air-side thermal resistance with fin-like structures can greatly improve overall cooling performance. The performance of these structures is usually characterized by the rate of heat which can be transferred and the pumping power required. One promising solution is to use a high-thermal-conductivity material with a large surface per unit volume such as carbon foam. This study presents a method of utilizing V-shape corrugated carbon foam. The air-side heat transfer coefficient and the pressure drop across the foam have been …

Three-Phase Contact Line Phenomena In Droplets On Solid And Liquid Surfaces: Electrocapillary, Pinning, Wetting Line Velocity Effect, And Free Liquid Surface Deformation, Roxana Shabani

Electronic Theses and Dissertations

In this dissertation physical phenomena relevant to (i) an interface formed between two fluids and a solid phase (wetting line) and (ii) an interface between three fluids (triple contact line) were investigated. In the former case, the wetting line (WL) phenomena which encompass the wetting line energy (WLE) or pinning, the wetting line velocity (WLV), and the contact angle hysteresis, were studied using a micropump based on electrowetting on dielectric (EWOD). In the latter case, the interfacial phenomena such as the air film lubrication effect and the liquid free surface deformation were taken into account to explain the dual equilibrium …