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Analysis Of Viscous Drag Reduction And Thermal Transport Effects For Microengineered Ultrahydrophobic Surfaces, Jason W. Davies Mar 2006

Analysis Of Viscous Drag Reduction And Thermal Transport Effects For Microengineered Ultrahydrophobic Surfaces, Jason W. Davies

Theses and Dissertations

One approach recently proposed for reducing the frictional resistance to liquid flow in microchannels is the patterning of micro-ribs and cavities on the channel walls. When treated with a hydrophobic coating, the liquid flowing in the microchannel wets only the top surfaces of the ribs, and does not penetrate into the cavities, provided the pressure is not too high. The net result is a reduction in the surface contact area between channel walls and the flowing liquid. For micro-ribs and cavities that are aligned normal to the channel axis (principal flow direction), these micropatterns form a repeating, periodic structure. This ...


Two Dimensional Friction Stir Welding Model With Experimental Validation, Charles Blake Owen Mar 2006

Two Dimensional Friction Stir Welding Model With Experimental Validation, Charles Blake Owen

Theses and Dissertations

The performance of a coupled viscoplastic model of FSW has been evaluated over a variety of tool RPMs and feed rates. Initial results suggested that further optimization of the material parameters and an additional ability to model the thermal recovery of the material would improve the overall performance of the model. Therefore, an experimental/numeric approach was taken to improve and quantitatively compare the performance of the model based upon the thermal profile of the workpiece. First, an experimental method for obtaining real-time temperature measurements during Friction Stir Processing (FSP) of 304L Stainless Steel was developed. The focus of the ...


Automatic Geometric Data Migration Throughout Views Of A Model Fidelity Family, Hans L. Soderquist Mar 2006

Automatic Geometric Data Migration Throughout Views Of A Model Fidelity Family, Hans L. Soderquist

Theses and Dissertations

Changes in geometric model parameters are constant throughout the design process. Each group in an organization needs different model information at varying times during the design process. As a result many different models of the same part or assembly arise for the needs and use of each group in each design phase (from conceptual design to full product definition). When one group makes changes to a model, those changes need to be reflected in all of the models which describe the product in all groups and design phases in order for those changes to be verified against all design criteria ...


Variation Analysis Of Involute Spline Tooth Contact, Brian J. De Caires Feb 2006

Variation Analysis Of Involute Spline Tooth Contact, Brian J. De Caires

Theses and Dissertations

The purpose of this thesis is to provide an in-depth understanding of tooth engagement in splined couplings based on variations in clearances between mating teeth. It is standard practice to assume that 25-50% of the total spline teeth in a coupling are engaged due to variations from manufacture. Based on the assumed number of teeth engaged, the load capability of a splined coupling is determined. However, due to the variations in tooth geometry from manufacuture, the number of teeth actually engaged is dependent on the applied load and the tooth errors. The variations result in sequential tooth engagement with increasing ...


Settling-Time Improvements In Positioning Machines Subject To Nonlinear Friction Using Adaptive Impulse Control, Tim Hakala Jan 2006

Settling-Time Improvements In Positioning Machines Subject To Nonlinear Friction Using Adaptive Impulse Control, Tim Hakala

Theses and Dissertations

A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These ...


Experimental Study On Two-Dimensional Propagating Edge Flames: Cold Flow Modeling And Flame Spread Rate Measurements, Marcos Villa-Gonzalez Jan 2006

Experimental Study On Two-Dimensional Propagating Edge Flames: Cold Flow Modeling And Flame Spread Rate Measurements, Marcos Villa-Gonzalez

Theses and Dissertations

This thesis presents the results of an experimental study on two-dimensional, planar propagating edge flames. The results were generated using a new apparatus in which a thin stream of gaseous fuel is injected into a low-speed laminar wind tunnel thereby forming a flammable layer along the centerline. The fuel injector consists of aluminum airfoil with a thin slot in its trailing edge, from which fuel is injected. After the initial stratified fuel/air layer is developed, a flame is ignited near the tunnel outlet, and the flame spreads against the incoming air, toward the fuel source. Experiments were conducted with ...


Remote Terrain Navigation For Unmanned Air Vehicles, Stephen R. Griffiths Jan 2006

Remote Terrain Navigation For Unmanned Air Vehicles, Stephen R. Griffiths

Theses and Dissertations

There are many applications for which small unmanned aerial vehicles (SUAVs) are well suited, including surveillance, reconnaissance, search and rescue, convoy support, and short-range low-altitude perimeter patrol missions. As technologies for microcontrollers and small sensors have improved, so have the capabilities of SUAVs. These improvements in SUAV performance increase the possibility for hazardous missions through mountainous and urban terrain in the successful completion of many of these missions. The focus of this research was on remote terrain navigation and the issues faced when dealing with limited onboard processing and limited payload and power capabilities. Additional challenges associated with canyon and ...


Cellular Damage Due To The Repetitive Opening Of Fluid-Filled Lung Regions, Stephen Preite Jan 2006

Cellular Damage Due To The Repetitive Opening Of Fluid-Filled Lung Regions, Stephen Preite

Theses and Dissertations

No abstract provided.


Simulations Of Gear-Based Systems Including Backlash, Edward J. Burke Jan 2006

Simulations Of Gear-Based Systems Including Backlash, Edward J. Burke

Theses and Dissertations

No abstract provided.


Fluid-Structure Analysis Of Microparticle Transport In Deformable Pulmonary Alveoli, Hannah L. Dailey Jan 2006

Fluid-Structure Analysis Of Microparticle Transport In Deformable Pulmonary Alveoli, Hannah L. Dailey

Theses and Dissertations

No abstract provided.


An Experimental Investigation Of Runner Based Flow Imbalances During Injection Molding Processes In Multicavity Molds, Rhyu Kevin Takarada Jan 2006

An Experimental Investigation Of Runner Based Flow Imbalances During Injection Molding Processes In Multicavity Molds, Rhyu Kevin Takarada

Theses and Dissertations

No abstract provided.


Advancements In Cooling Solutions For Powerful Processor Multi-Chip Modules Using Precision Gap Technology, Adreanne A. Kelly Jan 2006

Advancements In Cooling Solutions For Powerful Processor Multi-Chip Modules Using Precision Gap Technology, Adreanne A. Kelly

Theses and Dissertations

No abstract provided.


Pressure Drop Along Generic Hemodialysis Catheters, Zachary Fricker Jan 2006

Pressure Drop Along Generic Hemodialysis Catheters, Zachary Fricker

Theses and Dissertations

No abstract provided.


Characterization Of Polymer Based Gas Sensors With A Continuous System Model, Adolphe Alexander Jan 2006

Characterization Of Polymer Based Gas Sensors With A Continuous System Model, Adolphe Alexander

Theses and Dissertations

No abstract provided.


Comparison Of Potential Approaches For Resistive Wall Mode Stabilization Based On Plasma Eigenmode Model, Joseph A. Blair Jan 2006

Comparison Of Potential Approaches For Resistive Wall Mode Stabilization Based On Plasma Eigenmode Model, Joseph A. Blair

Theses and Dissertations

No abstract provided.


A Univariate Decomposition Method For Higher-Order Reliability Analysis And Design Optimization, Dong Wei Jan 2006

A Univariate Decomposition Method For Higher-Order Reliability Analysis And Design Optimization, Dong Wei

Theses and Dissertations

The objective of this research is to develop new stochastic methods based on most probable points (MPPs) for general reliability analysis and reliability-based design optimization of complex engineering systems. The current efforts involves: (1) univariate method with simulation for reliability analysis; (2) univariate method with numerical integration for reliability analysis; (3) multi-point univariate for reliability analysis involving multiple MPPs; and (4) univariate method for design sensitivity analysis and reliability-based design optimization.

Two MPP-based univariate decomposition methods were developed for component reliability analysis with highly nonlinear performance functions. Both methods involve novel function decomposition at MPP that facilitates higher-order univariate approximations ...


Stability Analysis Of Atomic Structures, Liang Zhang Jan 2006

Stability Analysis Of Atomic Structures, Liang Zhang

Theses and Dissertations

The stability and failure mechanism of a structure at the nanometer scale are important for understanding the mechanical behavior of nanoscale materials and structures. This thesis focuses on the material stability of atomic structures. First, the material stability of pristine carbon nanotubes is investigated at the continuum level by using the crystal elasticity theory. A homogenized continuum model is adopted. The strong ellipticity condition is employed to capture the localized failure of carbon nanotubes. The critical strain and strength predicted are reasonably comparable with experimental estimations.

An atomic material stability theory is developed as the atomistic counterpart of the continuum ...


Wheel Loader Powertrain Modeling For Real-Time Vehicle Dynamic Simulation, Matthew Michael Tinker Jan 2006

Wheel Loader Powertrain Modeling For Real-Time Vehicle Dynamic Simulation, Matthew Michael Tinker

Theses and Dissertations

No abstract provided.


The Effect Of Porosity On The Fatigue Life Of 8630 Cast Steel, Paul T Deegan Jan 2006

The Effect Of Porosity On The Fatigue Life Of 8630 Cast Steel, Paul T Deegan

Theses and Dissertations

The fatigue life of 8630 cast steel is studied by employing axial testing. The cast steel specimens are designed with varying levels of porosity and are verified using radiography and microscopy. A qualitative correlation can be made about the fatigue life to the amount/size of porosity that exists in cast steels based on the results.


An Adaptively Refined Cartesian Grid Method For Moving Boundary Problems Applied To Biomedical Systems, Sreedevi Krishnan Jan 2006

An Adaptively Refined Cartesian Grid Method For Moving Boundary Problems Applied To Biomedical Systems, Sreedevi Krishnan

Theses and Dissertations

A major drawback in the operation of mechanical heart valve prostheses is thrombus formation in the near valve region potentially due to the high shear stresses present in the leakage jet flows through small gaps between leaflets and the valve housing. Detailed flow analysis in this region during the valve closure phase is of interest in understanding the relationship between shear stress and platelet activation.

An efficient Cartesian grid method is developed for the simulation of incompressible flows around stationary and moving three-dimensional immersed solid bodies as well as fluid-fluid interfaces. The embedded boundaries are represented using Levelsets and treated ...


A Parallelized Sharp-Interface Fixed Grid Method For Moving Boundary Problems, Saikrishna V Marella Jan 2006

A Parallelized Sharp-Interface Fixed Grid Method For Moving Boundary Problems, Saikrishna V Marella

Theses and Dissertations

The primary objective of this thesis is to develop a general computational framework to perform large scale moving boundary problems in fluid mechanics. The interactions of moving entities with fluid flow are common to numerous engineering and biomedical applications. The novel computational platform developed comprises of a) an efficient fluid flow solver b) an accurate and easily implemented unified formulation to capture the interactions of the moving bodies with the flow and c) parallel execution capability to enable large scale computations. The above features are formulated and implemented in a computer code, ELAFINT3D. The current thesis demonstrates the accuracy, efficiency ...