Mechanical Engineering Commons^™

Modeling The Dynamics And Stresses Of Elongated Particles In Vertical Axis Mixers, Xia Hua

Open Access Dissertations

Vertical axis mixers, such as high shear granulators and agitated filter dryers (AFDs), are commonly used in the processing of particulate materials. For example, AFDs are regularly used in the pharmaceutical industry to dry the wet active pharmaceutical ingredient (API) particles. During the drying process, an impeller blade agitates the bed to increase the drying rate and enhance drying uniformity. Unfortunately, the needle-shaped API particles tend to flow poorly, are frequently damaged, and can sometimes form undesirable agglomerates, causing manufacturing inefficiencies, flow stoppages, and unpredictable product quality. Therefore, it is important to gain an improved understanding of the system's particle …

Thermoelectric Waste Heat Recovery In Automobile Exhaust Systems: Topological Studies And Performance Analysis, Sumeet Kumar

Open Access Dissertations

The demand for improved fuel efficiency in automobiles has placed an emphasis on exhaust system waste heat recovery as a 40% of the fuel's chemical energy is lost to the environment in modern spark ignition engines. To advance fuel economy, researchers are currently evaluating technologies to exploit exhaust stream thermal power using thermoelectric generators (TEGs) that operate using the Seebeck effect. Thermoelectric generators have the potential to recover some of this waste energy in the exhaust stream potentially improving fuel economy by as much as 5%. ^ Attempts are made to maximize the electrical power generation by optimizing the thermoelectric …

Investigation Of Optical Near Field Using Near Field Scanning Optical Microscopy, Yan Li

Open Access Dissertations

Conventional optical imaging techniques have a fundamental resolution limit due to the diffraction limit of light. The advances of science and technology on the nanoscale demand a new tool for characterization. The Near Field Scanning Optical Microscopy (NSOM) has been developed to tackle certain aspects of this problem. The work presented here applies different types of NSOM to explore the near field distribution of metal plasmonic nanostructures.^ Ridge apertures with shapes like bowtie and C can be used to focus light into sub-diffraction limit spot with enhancement. This localization of the field near the exit of a bowtie aperture is …

The Role Of Microstructure On The Combustion And Impact Behavior Of Mechanically Activated Nickel/Aluminum Reactive Composites, Benjamin Aaron Mason

Open Access Dissertations

Metal-based reactive composites are a class of materials that consist of at least one metals, such as Ni/Al, that have high-energy densities and can produce significant energy output during exothermic reaction after thermal or mechanical initiation. However, conventionally these materials typically have slow reaction rates and are difficult to ignite at typical micron particle size ranges limiting their application. Therefore, mechanical activation techniques have been used to create materials with high surface areas and smaller characteristic dimensions in order to increase combustion velocity and ignition sensitivity. Their combustion and mechanical impact behavior is being studied to develop the understanding needed …

Structure-Functionality Relationship Of Collagen Scaffolds For Tissue Engineering, Seungman Park

Open Access Dissertations

Tissue engineering is a promising technology that enables scientists to create artificial organs or replace damaged tissues using animal cells and other components. For successful tissue regeneration, many factors should be taken into account, however, three components are most crucial: cell, scaffold, and soluble factor(s). In order to check the functionality after regeneration of desired tissues, various approaches have been attempted, depending on the physical, biological, and chemical properties of the tissues. Recently, the importance of the extracellular matrix (ECM) microstructure is being considered to be important in this regard. The ECM is closely associated with various functional properties of …

Effects Of Flow Orientation On Condensation In Tubes, Il Chung Park

Open Access Dissertations

This study explores the interfacial and heat transfer characteristics of annular condensation of FC-72 in vertical downflow, vertical upflow and horizontal flow as well as the effects of channel orientation on flow condensation. Two separate condensation test modules are employed, one for high-speed video imaging of the film interface and the second for heat transfer measurements. Condensation in both test modules is achieved by rejecting the heat to a counterflow of cooling water. The heat transfer measurements are obtained along the inner wall of an 11.89-mm i.d. and 1,259.84-mm long stainless steel tube. ^ For vertical downflow, the film at …

Non-Intrusive Two-Phase Flow Regime Identification And Transport Characterization In Microchannels Subject To Uniform And Non-Uniform Heat Input, Susan N. Ritchey

Open Access Dissertations

Direct integration of compact microchannel heat sinks is an attractive thermal management solution for the dissipation of high heat fluxes, specifically under boiling conditions that provide high rates of heat transfer at a uniform heat sink temperature. Under two-phase flow conditions, the heat transfer and pressure drop are a function of the local flow regime. Development of sensors that detect local void fraction and flow regimes may enable better understanding of the fundamental flow phenomena. ^ The void fraction in air-water two-phase adiabatic flow in a microchannel is measured in this work using a custom-designed impedance-based sensor with electrodes on …

Predicting Lubrication Performance Between The Slipper And Swashplate In Axial Piston Hydraulic Machines, Andrew T. Schenk

Open Access Dissertations

Engineering of the sliding interfaces within swashplate type axial piston machines represents the most complex and difficult part of the design process. The sliding interfaces are subject to significant normal loads which must be supported while simultaneously preventing component wear to ensure long lasting operation. Proper lubrication design is essential to separate the solid bodies from each other, but the complexity of the physics involved makes this a difficult problem. This work focuses on lubrication and the resulting energy losses at the sliding interface between the slipper and swashplate. ^ To better understand the slipper lubrication performance, a numerical model …

Understanding Preferred Leg Stiffness And Layered Control Strategies For Locomotion, Zhuohua H. Shen

Open Access Dissertations

Despite advancement in the field of robotics, current legged robots still cannot achieve the kind of locomotion stability animals and humans have. In order to develop legged robots with greater stability, we need to better understand general locomotion dynamics and control principles. Here we demonstrate that a mathematical modeling approach could greatly enable the discovery and understanding of general locomotion principles. ^ It is found that animal leg stiffness when scaled by its weight and leg length falls in a narrow region between 7 and 27. Rarely in biology does such a universal preference exist. It is not known completely …

Algebraic Level Sets For Cad/Cae Integration And Moving Boundary Problems, Kritika Upreti

Open Access Dissertations

Boundary representation (B-rep) of CAD models obtained from solid modeling kernels are commonly used in design, and analysis applications outside the CAD systems. Boolean operations between interacting B-rep CAD models as well as analysis of such multi-body systems are fundamental operations on B-rep geometries in CAD/CAE applications. However, the boundary representation of B-rep solids is, in general, not a suitable representation for analysis operations which lead to CAD/CAE integration challenges due to the need for conversion from B-rep to volumetric approximations. The major challenges include intermediate mesh generation step, capturing CAD features and associated behavior exactly and recurring point containment …

Model-Based Powertrain Design And Control System Development For The Ideal All-Wheel Drive Electric Vehicle, Haotian Wu

Open Access Dissertations

The transfer case based all-wheel drive electric vehicle (TCAWDEV) and dual-axle AWDEV have been investigated to balance concerns about energy consumption, drivability and stability of vehicles. However, the mentioned powertrain architectures have the torque windup issue or the wheel skidding issue. The torque windup is an inherent issue of mechanical linked all-wheel drive systems. The hydraulic motor-based or the electric motor-based ideal all-wheel drive powertrain can provide feasible solutions to the mentioned issues. An ideal AWDEV (IAWDEV) powertrain architecture and its control schemes were proposed by this research; the architecture has four independent driving motors in powertrain. The IAWDEV gives …

Coal Gasification For Fuel Synthesis: Multiphysics Modeling And New Concepts, Jian Xu

Open Access Dissertations

Fuel synthesis through gasification of carbonaceous materials (e.g. coal and biomass) has the potential to provide a solution to the increasing demand for energy and liquid transportation fuels. To theoretically understand the complex physical and chemical processes in a gasifier and to identify the most influential parameters for syngas production, we first developed a multi-physics and multi-scale model to simulate the gasification processes in a well-stirred reactor. This model is the first of its kind and considers detailed gas-phase chemistry, particle-phase reactions, moisture drying, devolatilization, porous structure evolution, convective and radiative heat transfer, as well as full coupling between the …

Development Of Methodologies For Evaluating Performance Of Fault Detection And Diagnostics Protocols Applied To Unitary Air-Conditioning Equipment, David P. Yuill

Open Access Dissertations

This thesis describes the development of standardized methodologies and methods for evaluating the performance of fault detection and diagnostics (FDD) protocols that are intended for air-cooled vapor compression unitary air-conditioners. Although there are currently many FDD protocols available commercially and there are jurisdictions in which the building codes require FDD, there is currently no standardized method to determine how effective the FDD might be at detecting and diagnosing faults.^ An FDD evaluation method is proposed, in which the evaluator passes data from a large number of scenarios to a candidate FDD protocol, and collects the responses from each scenario. The …

Ultrashort Laser Pulse-Matter Interaction: Fundamentals And Early Stage Plasma Dynamics, Xin Zhao

Open Access Dissertations

Despite extensive studies for many years, the detailed mechanisms of ultrashort laser pulse (USLP)-matter interaction are still not fully understood and further fundamental investigation is required. This study seeks to provide an improved understanding of the USLP-material interaction by both theoretical and experimental investigations and to find ways to enhance laser energy coupling with different materials.^ A two-dimensional comprehensive hydrodynamic model for USLP ablation of metals and semiconductors is developed in this study. The model comprises a two-temperature model and a hydrodynamic model supplemented with a quotidian equation of state model, considering the relevant multiphysical phenomena during the laser-matter interaction. …

Unsteady Flamelet Progress Variable Modeling Of Reacting Diesel Jets, Muhsin Mohammed Ameen

Open Access Dissertations

Accurate modeling of turbulence/chemistry interactions in turbulent reacting diesel jets is critical to the development of predictive computational tools for diesel engines. The models should be able to predict the transient physical and chemical processes in the jets such as ignition and flame lift-off. In the first part of this work, an existing unsteady flamelet progress variable (UFPV) model is employed in Reynolds-averaged Navier-Stokes (RANS) simulations and large-eddy simulations (LES) to assess its accuracy. The RANS simulations predict that ignition occurs toward the leading tip of the jet, followed by ignition front propagation toward the stoichiometric surface, and flame propagation …

Droplet Behavior On Superhydrophobic Surfaces: Interfaces, Interactions, And Transport, Susmita Dash

Open Access Dissertations

The primary objective of the present work is to study droplet dynamics on smooth hydrophobic and textured superhydrophobic surfaces, and to understand the dependence of interfacial interaction mechanisms on surface morphology. ^ A detailed understanding of the dynamics of droplet response to an applied electric field is essential for implementation of electrowetting techniques in various devices. In the first part of the thesis, a systematic study of the transient response in terms of contact angle and contact radius of a sessile droplet on a smooth hydrophobic surface under electrical actuation is presented. A scaling analysis predicts the response time of …

2014 (Fall) Ensi Informer Magazine, Morehead State University. Engineering Sciences Department

ENSI Informer Magazine Archive

The ENSI Informer Magazine published in the fall of 2014.

A Regression Approach For Estimation Of Anthropogenic Heat Flux Based On A Bottom-Up Air Pollutant Emission Database, Sanghyun Lee, Stuart A. Mckeen, David J. Sailor

Mechanical and Materials Engineering Faculty Publications and Presentations

A statistical regression method is presented for estimating hourly anthropogenic heat flux (AHF) using an anthropogenic pollutant emission inventory for use in mesoscale meteorological and air-quality modeling. Based on bottom-up AHF estimated from detailed energy consumption data and anthropogenic pollutant emissions of carbon monoxide (CO) and nitrogen oxides (NO_x) in the US National Emission Inventory year 2005 (NEI-2005), a robust regression relation between the AHF and the pollutant emissions is obtained for Houston. This relation is a combination of two power functions (Y = aX^b) relating CO and NO_x emissions to AHF, giving a determinant …

Co-Firing Biomass With Biogas In Cookstoves With A Fan, Manil Poudyal

Theses and Dissertations

Co-firing is a combustion process in which more than one type of fuel is used. In many cases, co-firing reduces fuel costs and/or reduces the environmental impact. The objective of this research was to test the hypothesis that adding biogas to be co-fired with biomass in a traditional cookstove reduces indoor air pollution and increases the combustion efficiency. The impact of co-firing on indoor air pollution is assessed by comparing the concentrations of carbon monoxide and particulate matter in the exhaust stream of a co-fired cookstove to a cookstove fueled with biomass alone. The concentrations of each of these pollutants …

Within-Socket Myoelectric Prediction Of Continuous Ankle Kinematics For Control Of A Powered Transtibial Prosthesis, Samuel Farmer, M. Barbara Silver-Thorn, Philip A. Voglewede, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Objective. Powered robotic prostheses create a need for natural-feeling user interfaces and robust control schemes. Here, we examined the ability of a nonlinear autoregressive model to continuously map the kinematics of a transtibial prosthesis and electromyographic (EMG) activity recorded within socket to the future estimates of the prosthetic ankle angle in three transtibial amputees. Approach. Model performance was examined across subjects during level treadmill ambulation as a function of the size of the EMG sampling window and the temporal 'prediction' interval between the EMG/kinematic input and the model's estimate of future ankle angle to characterize the trade-off between model error, …

Electric Vehicle Life Cycle Cost Assessment, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

The Electric Vehicle Transportation Center (EVTC) has developed a life cycle cost (LCC) model to include all reasonable costs associated with vehicle ownership over a 5, 10, 15, or 20-year period. The EVTC LCC model compares ownership costs of conventional vehicles to plug-in hybrid and battery electric vehicles. Internal combustion engines using gasoline, ethanol, or diesel are considered. The analysis includes costs for tires, insurance and maintenance, federal incentives, state tax, dealership fee, and financed interest payments. Traction battery replacement costs are difficult to ascertain yet are included to investigate their impact on overall life cycle costs. Economic factors used …

Control Of The Diffracted Response Of A Metallic Wire Array With Double Period: Experimental Demonstration, Nicholas A. Roberts, D. C. Skigin, J. D. Fowlkes, L. B. Scaffardi, D. C. Schinca, M. Lester

Mechanical and Aerospace Engineering Faculty Publications

In recent papers, it has been theoretically shown that by using dual-period wire gratings, it is possible to control the relative efficiencies of the diffracted orders, regardless of the wires’ material, incident polarization and wavelength. In this Letter, we experimentally demonstrate, for the first time, that by appropriately choosing the geometrical parameters of a nanometric periodic structure, it is possible to control the optical response in the visible range. We show examples of nanostructures designed to cancel out or to intensify a particular diffraction order. Such nanostructures allow a broad control over the directionality and the intensity of the diffracted …

An Analysis Of Fuel Cell Vehicle Models By Major Automakers, Florida Solar Energy Center, Nan Qin

FSEC Energy Research Center®

Fuel cell electric vehicles (FCEVs) use hydrogen as fuel and exhaust only water. They provide driving ranges and fueling times comparable to gasoline vehicles. Despite the advantages, FCEVs have been in and out of spot light of the auto industry for the past several decades. The information on the development of fuel cell vehicles by major automakers is disparate. This report systematically examined the technical developments of FCEVs since the introduction of the first lab-based fuel cell vehicle in 1966. It included an overview of 117 FCEV models from 31 automakers. It should help the stakeholders to gain an insight …

Convective Heat Transfer With And Without Film Cooling In High Temperature, Fuel Rich And Lean Environments, Nathan K. Greiner

Theses and Dissertations

Modern turbine engines require high turbine inlet temperatures and pressures to maximize thermal efficiency. Increasing the turbine inlet temperature drives higher heat loads on the turbine surfaces. In addition, increasing pressure ratio increases the turbine coolant temperature such that the ability to remove heat decreases. As a result, highly effective external film cooling is required to reduce the heat transfer to turbine surfaces. Testing of film cooling on engine hardware at engine temperatures and pressures can be exceedingly difficult and expensive. Thus, modern studies of film cooling are often performed at near ambient conditions. However, these studies are missing an …

Design Of A Frequency-Selective Surface Strain Sensor, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Frequency Selective Surfaces (FSS) have long been used in the RF/microwave community to control radar cross-section. The scattering parameters of the FSS form a signature which is a function of the frequency, element size and spacing, as well as the local electromagnetic environment. This paper considers a FSS as a strain sensor on the surface of a structural element. By interrogating the FSS with a series of polarized far-field measurements in a bistatic configuration the biaxial plane strain, including shear, can be resolved.

Long-Lasting Effect Of Initial Configuration In Gravitational Spreading Of Material Fronts, ‪Nadim Zgheib, Thomas Bonometti, S. Balachandar

Mechanical Engineering Faculty Publications

We present the results from laboratory experiments and fully resolved simulations pertaining to finite-release turbulent density flows with a non-axisymmetric initial shape. First, we demonstrate that the effects of the initial shape influence the current’s evolution well into the long-time phase which would corresponds to the inertial self-similar phase in the case of planar or axisymmetric configurations. Then, we identify the physical mechanisms responsible for this dependence and propose a new model capable of capturing the dynamics of such releases. Finally, we show that this dependence on the initial configuration is robust for various types of gravity currents over a …

Mechanical Engineering News, Georgia Southern University

Mechanical Engineering: News & Publications (2013-2023)

• Dr. Soloiu wins Award for Excellence in Research

• Dr. Mitra wins Award for Excellence in Service

A Collagen‐Glycosaminoglycan‐Fibrin Scaffold For Heart Valve Tissue Engineering Applications, Claire Brougham, Stefan Jockenhoevel, Thomas Flanagan, Fergal O'Brien

Conference Papers

The field of heart valve biology and tissue engineering a heart valve continue to expand. The presentatio ns at this meeting reflect the advances made in both areas due to the multi-disciplinary approach taken by many laboratories.

A Control-Chart Based Method For Solder Joint Crack Detection, Jianbiao Pan

Industrial and Manufacturing Engineering

Many researchers have used different failure criteria in published solder joint reliability studies. Since the reported timeto-failure would be different if different failure criteria were used, it would be difficult to compare the reported reliability life of solder joints from one study to another. The purpose of this study is to evaluate the effect of failure criteria on the reported thermal fatigue life and determine which failure criterion could detect failure sooner. First, the application of the control-chart-based method in a thermal cycling reliability study is described. The reported time-to-failure data were then compared based on four different failure criteria: …

Serious Fun: Using Toys To Demonstrate Fluid Mechanics Principles, Camilla M. Saviz, Said Shakerin

All Faculty Articles - School of Engineering and Computer Science

Many students have owned or seen fluids toys in which two immiscible fluids within a closed container can be tilted to generate waves. These types of inexpensive and readily available toys are fun to play with, but they are also useful for provoking student learning about fluid properties or complex fluid behavior, including drop formation and coalescence. Including these toys in a class or lab with a companion exercise allows students to use observation and inductive reasoning to infer principles-all while having fun.