Mechanical Engineering Commons^™

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 …

Team Nathan Suspension, Frankie J. Wiggins, Alex D. Seitz, Justin P. Bautista

Mechanical Engineering

Nathan Cooper is an 8-year old boy with Spinal Muscular Atrophy (SMA). SMA has affected Nathan’s muscle development and requires him to use the Standing Dani™ mobility device. The Standing Dani is a motorized standing wheelchair, or Wheelstand. Nathan controls and uses it to get around. Though the Standing Dani performs well for most functions, it has some distinct issues. The primary issue that this project addresses is its lack of suspension and the discomfort that Nathan feels as a result. After talking with our client, we developed several specifications generally related to geometry, safety, vehicle dynamics, and reliability. Many …

A Study Of Shock Analysis Using The Finite Element Method Verified With Euler-Bernoulli Beam Theory; Mechanical Effects Due To Pulse Width Variation Of Shock Inputs; And Evaluation Of Shock Response Of A Mixed Flow Fan, David Jonathan Gonzalez Campos

Master's Theses

A Study Of Shock Analysis Using The Finite Element Method Verified With Euler-Bernoulli Beam Theory; Mechanical Effects Due To Pulse Width Variation Of Shock Inputs; And Evaluation Of Shock Response Of A Mixed Flow Fan

David Jonathan González Campos

For many engineers that use finite element analysis or FEA, it is very important to know how to properly model and obtain accurate solutions for complicated loading conditions such as shock loading. Transient acceleration loads, such as shocks, are not as common as static loads. Analyzing these types of problems is less understood, which is the basis for this study. FEA …

Leveraging Students’ Passion And Creativity: Ethos At The University Of Dayton, Margaret Pinnell, Malcolm Daniels, Kevin P. Hallinan, Gretchen Berkemeier

Mechanical and Aerospace Engineering Faculty Publications

The Engineers in Technical Humanitarian Opportunities of Service-learning (ETHOS) program was developed in the spring of 2001 by an interdisciplinary group (electrical, chemical, civil and mechanical) of undergraduate engineering students at the University of Dayton (UD). ETHOS was founded on the belief that engineers are more apt and capable to appropriately serve our world if they have an understanding of technology’s global linkage with values, culture, society, politics, and the economy. Since 2001, the ETHOS program at UD has grown and changed.

From conceptualization, to implementation, to maturation and national recognition, the program has addressed challenges of academic acceptance, programmatic …

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 …

Bio-Inspired Robotic Fish With Vision Based Target Tracking, Eric Anderson

Open Access Theses

The lionfish is an invasive species that out-competes and overcrowds native sh species along the eastern seaboard of the United States and down into the Caribbean. Lionfish populations are growing rapidly. Current methods of monitoring lionfish populations are costly and time intensive. A bio-inspired robotic fish was built to use as an autonomous lionfish tracking platform. Lionfish are tracked visually using an onboard processor. Five different computer vision methods for identification and tracking are proposed and discussed. These include: background subtraction, color tracking, mixture of Gaussian background subtraction, speeded up robust feature (SURF), and CamShift based tracking. Each of these …

Experimental Characterization Of Cu Free-Air Ball And Simulations Of Dielectric Fracture During Wire Bonding, Sai Sudharsanan Paranjothy

Open Access Theses

Wire bonding is the process of forming electrical connection between the integrated circuit (IC) and its structural package. ICs made of material with low dielectric constant (low-k) and ultra low-k are porous in nature, and are prone to fracture induced failure during packaging process. In recent years, there is increasing interest in copper wire bond technology as an alternative to gold wire bond in microelectronic devices due to its superior electrical performance and low cost. Copper wires are also approximately 25% more conductive than Au wires aiding in better heat dissipation. At present, validated constitutive models for the strain rate …

Investigation Of Microstructural Alterations In M50 And 52100 Steel Using Nanoindentation, Kristin R. Paulson

Open Access Theses

Bearing steels are used in rolling elements and are designed to withstand heavy loads for an extended period of time. At the end of life, microstructural alterations within the material have been observed and are linked to failure. In this study, a three ball-on-rod fatigue tester was used to test M50 and 52100 steel cylindrical rods at differing loads of 4.0 GPa, 4.5 GPa, and 5.0 GPa and in lubricated and unlubricated conditions to 10 8 cycles in an attempt to produce microstructural alterations. Microstructural alterations characterized as butterflies were observed and investigated further in two M50 samples that were …

Wind Walking Machine, Sam N. Lazechko, Taylor A. Justman, Will Nocka, Isaac Goldenthal

Mechanical Engineering Design Project Class

Design a machine that walks using wind power.

Treadle Driven Lathe, Eleanor B. Mullard, Daniel Kronthal, Aaron Cohn, Robert Borovsky

Mechanical Engineering Design Project Class

The main objective of this senior design project was to design and build a treadle-driven, metal-cutting lathe that has the ability to cut 3/4" diameter material and produce small parts up to 3" long. The main challenge in this project was to successfully generate enough power through the treadle driven system to successfully cut metal at the proper specifications, while simultaneously meeting all of the user-needs. The entire system needed to be operated and pedaled by a single person, which put constraints on the location of the treadle relative to the lathe itself so the user could comfortably operate both …

Treadle Driven Can Opener, Chris Lowery, Stewart Martens, Dom Quaranta

Mechanical Engineering Design Project Class

Given the task to build a treadle driven can opener that opened a can in under 5 seconds, met cost requirements, and was robust.

Orthopedic Screwdriver Design, Tiffany M. Ewing, Ryan F. Blumenstein, Beenish Qayum

Mechanical Engineering Design Project Class

Design an adjustable mechanical clutch screwdriver suitable for driving Orthopedic Screws into bones. The clutch would prevent over tightening and damaging bone material. The prototype design must demonstrate the function and ergonomics of the device and it must be suitable for modification into a medical device. Specify material changes and design details that would be needed for the ultimate production model.

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 …

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.

Nanogap Device: Fabrication And Applications, Jun Hyun Han

Dissertations (1934 -)

A nanogap device as a platform for nanoscale electronic devices is presented. Integrated nanostructures on the platform have been used to functionalize the nanogap for biosensor and molecular electronics. Nanogap devices have great potential as a tool for investigating physical phenomena at the nanoscale in nanotechnology. In this dissertation, a laterally self-aligned nanogap device is presented and its feasibility is demonstrated with a nano ZnO dot light emitting diode (LED) and the growth of a metallic sharp tip forming a subnanometer gap suitable for single molecule attachment.

For realizing a nanoscale device, a resolution of patterning is critical, and many …

Control Of A Spacecraft Using Mixed Momentum Exchange Devices, Blake J. Currie

Master's Theses

Hardware configurations, a control law, and a steering law are developed for a mixed hardware spacecraft that uses both control moment gyros and reaction wheels. Replacing one or more gyros in a spacecraft with a reaction wheel has potential for cost savings while still achieving much greater performance than using reaction wheels alone. Several simulated tests are run to compare the performance to a traditional all reaction wheel or all control moment gyro spacecraft, including analysis of failure modes and singular configurations. The mixed system performed similarly to all gyro systems, responding within 6% of the gyro system’s time for …