Mechanical Engineering Commons^™

Modeling Electrospun Fibrous Materials, Sina Hassanpouryousefi

Theses and Dissertations

Electrospinning has been the focus of countless studies for the past decades for applications, including but not limited to, filtration, tissue engineering, and catalysis. Electrospinning is a one-step process for producing nano- and/or micro-fibrous materials with diameters ranging typically from 50 to 5000 nm. The simulation algorithm presented here is based on a novel mass-spring-damper (MSD) approach devised to incorporate the mechanical properties of the fibers in predicting the formation and morphology of the electrospun fibers as they travel from the needle toward the collector, and as they deposit on the substrate. This work is the first to develop a …

Investigation Of Various Factors Affecting Quantification And Characterization Accuracy Of Nox Measurement At Near Zero Level In A Cvs Sampling Set-Up, Samuel Abimbola Ogunfuye

Graduate Theses, Dissertations, and Problem Reports (ETD)

Accurate measurement of oxides of nitrogen (NOx) concentrations at near-zero levels using the constant volume sampling (CVS) system is a critical consideration in emissions quantification for engine and vehicle research and certification purposes. Various technological efforts and research are being implemented to ensure emissions from automobile and on-road transportation sources tend towards lower concentrations. This development has resulted in NOx concentration measurements to shift towards near-zero and thus, reach the detection limits of traditional measurement approaches and methods. There are several factors that might deter achieving measurement accuracy at this level, as their effect becomes significant at low NOx concentrations. …

Propagation And Morphology Of Premixed Flames In Obstructed Channels Under Atmospheric And Supercritical Conditions, Abdulafeez Akinola Adebiyi

Graduate Theses, Dissertations, and Problem Reports (ETD)

The understanding of the morphology and propagation of premixed flames in channels is vital for the design and development of efficient propulsion systems requiring high heat release, such as pulse detonation engines, and for resolving accidental fire in industrial conduits. In this work, extensive computational simulation of premixed flames in channels (with rectangular and cylindrical cross sections) with closely packed obstacles are carried out with the goal of providing insights into flame propagation under various conditions which would be invaluable to the development and safety of energy and propulsion systems as well as for the mitigation of accidental fires in …

Design Of Experiment And Analysis Techniques For Fuel Consumption Data Using Heavy-Duty Diesel Vehicles And On-Road Testing, Sarah Ann Mills

Graduate Theses, Dissertations, and Problem Reports (ETD)

Chassis dynamometer and on-road testing are usually employed to test vehicle operation. Testing on a chassis dynamometer reduces data variability compared to on-road testing due to the controlled environment but it does not account for other important variables that affects real-world vehicle operation. This study used on-road testing to investigate the differences between two test fuels under real-world conditions. Three heavy-duty diesel vehicles were driven on different routes for a period of three months. Each vehicle was instrumented with flow meters to gather fuel consumption data, which was then compared to the fuel rate broadcasted by the engine control unit …

Experimental Measurement Of Dielectric Properties Of Powdery Materials Using A Coaxial Transmission Line, Robert Tempke

Graduate Theses, Dissertations, and Problem Reports (ETD)

This study proposes a standard methodology for coaxial dielectric property measurements of powdery materials (1-10GHz) using a coaxial transmission line. Four powdery materials with dielectric constants ranging from 3.5 to 70 (SiO2, Al2O3, CeO2, and TiO2) were experimentally investigated at varying volume loading fractions in a paraffin mixture. A statistically significant number of paraffin heterogeneous-mixtures was synthesized for all dielectric powders. The dielectric properties of the constitutive materials were determined using appropriate mixture equations. The sensitivity of the equations dielectric prediction to volume loading is discussed with guidance on selecting the best mixing equation. It was determined that low volume …

In Situ Measurement Of Fatigue Induced Crack Growth In Inconel 718 Using Direct Current Potential Drop Method, Joel C. Lindsay

Graduate Theses, Dissertations, and Problem Reports (ETD)

With recent advances in air breathable engines comes more extreme temperature environments that engine components must tolerate. During the design of these engines, it is necessary to understand how material fatigue failures occur at these new, higher operating temperatures. In providing understanding, the following fundamental study focuses on the statistical nature of crack jumps (changes in crack length over time) during fatigue in a polycrystalline nickel-based superalloy, Inconel 718 (IN718). In situ measurement of the crack length at several loading conditions were conducted using a direct current potential drop (DCPD) measurement method. Experimental data was collected at six different fatigue …

Reliability Analysis For Systems With Outsourced Components, Zhengwei Hu

Doctoral Dissertations

"The current business model for many industrial firms is to function as system integrators, depending on numerous outsourced components from outside component suppliers. This practice has resulted in tremendous cost savings; it makes system reliability analysis, however, more challenging due to the limited component information available to system designers. The component information is often proprietary to component suppliers. Motivated by the need of system reliability prediction with outsourced components, this work aims to explore feasible ways to accurately predict the system reliability during the system design stage. Four methods are proposed. The first method reconstructs component reliability functions using limited …

Investigation And Development Of Exhaust Flow Rate Estimation Methodologies For Heavy-Duty Vehicles, Chakradhar Reddy Vardhireddy

Graduate Theses, Dissertations, and Problem Reports (ETD)

Exhaust gas flow rate from a vehicle tailpipe has a great influence on emission mass rate calculations, as the emission fractions of individual gases in the exhaust are calculated by using the measured exhaust flow rate. The development of high-end sensor technologies and emission pollutant measurement instruments, which can give instantaneous values of volume concentration of pollutants flowing out of the engine are gaining importance because of their ease of operation. The volume concentrations measured can then be used with the instantaneous exhaust flow rate values to obtain mass flow rates of pollutants.

With the recent promulgation of real world …

Decentralized Hamiltonian Control Of Multi-Der Isolated Microgrids With Meshed Topology, Mohamed Toub, Rush Robinett, Mohamed Maaroufi, Ghassane Aniba

Michigan Tech Publications, Part 1

The new electricity grid of the future, smart grid, can be seen as the interconnection of multiple microgrids. These microgrids are usually composed of distributed energy resources (DERs) that connect to each other in different topologies. Therefore, the modeling and control of meshed microgrids are requisite. This paper presents a mathematical approach for the modeling and decentralized control of multi-DER isolated microgrids (ImGs) with a meshed topology. Based on the advanced control scheme: Hamiltonian surface shaping and power flow control (HSSPFC), decentralized controllers are designed independently using only local information. These controllers regulate the voltage at the point of common …

Comparison Of Drag Area Estimation Using Natural Coast Down And Constant Speed Test Methods, Cem Baki Mr

Graduate Theses, Dissertations, and Problem Reports (ETD)

Currently in US, more than 26 percent of the total GHG emissions comes from transportation and mostly from heavy duty vehicles. Similarly, the European Council stated that 25 percent of the emissions comes from heavy duty transportation and they expect it to be further increased in the future. However, with the new coming regulations US EPA and European Council aiming to reduce the emissions by 80 percent in US and 60 percent in EU. In order to keep track and control the emissions, both authorities published new regulations and testing methods for certifying the new vehicles.

Aerodynamic testing is one …

Scaling Analysis And Experimental Investigation Of A Rotating Detonation Engine, David Thomas Billups

Graduate Theses, Dissertations, and Problem Reports (ETD)

Pressure gain combustion (PGC) technologies, specifically rotating detonation engines (RDEs), are poised to provide the next big leap in gas turbine engine advancement, significantly increasing the thermal. RDEs make use of thermodynamic advantages of isochoric as opposed to isobaric combustion. Theorized to increase thermal efficiency by up to 7% [1], the RDE would have significant impact on reducing anthropogenic carbon emissions. In addition to efficiency gains, the RDE also provides mechanical simplicity and reduced size advantages compared to it’s traditional counterparts and PGC competition.

The United States (U.S.) Department of Energy (DOE) National Energy Technology Laboratory (NETL) maintains and operates …

Impact Of Implementing A Dedicated Outdoor Air System In Parallel With A Multi-Zone Variable-Air Volume System On Energy Consumption, Thermal Comfort, And Life Cycle Cost, Khaled Alghamdi

Graduate Theses, Dissertations, and Problem Reports (ETD)

Heating, Ventilating, and Air-Conditioning systems (HVAC) consume more than 40% of energy in commercial buildings, according to the Commercial Building Energy Consumption Survey in 2012. Therefore, efforts to reduce HVAC energy consumption would be significant in coping with energy-related issues. In that context and in order to enhance the indoor air quality without compromising for energy consumption, the concept of Dedicated Outdoor Air systems (DOAS) emerged.

The literature shows that the integration of DOAS with other HVAC systems has been studied widely, yet the impact of integrating DOAS in parallel with multi-zone Variable-Air Volume systems (multi-zone VAV) for an application …

Virtual Morphology As A Method Of Robotic Control, Conner Todd Castle

Graduate Theses, Dissertations, and Problem Reports (ETD)

This thesis presents Virtual Morphology (VM), a method that explores a different perspective on the design of robot autonomy using inspiration from morphological computing and programmed computation. Morphological computation offers physical solutions that solve complex tasks, like robotic grasping of unknown objects, with relative ease. Unfortunately, these physical solutions are difficult to adjust post-development, and are usually designed to complete only one or a few specific tasks. Programmed computational approaches are more flexible because they can be implemented and adjusted through software, but unfortunately, these approaches can become rather complex as tasks become more difficult. This thesis explores the potential …

Computational Design Of Staged Pressurized Oxy-Coal Combustion, Gideon Ozioma Udochukwu

Graduate Theses, Dissertations, and Problem Reports (ETD)

Staged pressurized oxy-coal combustion (SPOC) is nowadays a promising technology to be used for low-cost, low-emission, high-efficiency power generation. The objective of this thesis is to compliment the experiments ongoing at the Washington University, St. Louis (WUSTL) by means of numerical simulations, thereby providing better understanding of the fluid flow, turbulence, combustion characteristics, particle dynamics and heat transfer. Carbon dioxide (CO2) is injected alongside the coal, for its carriage. A small amount of methane (CH4) is also injected alongside the coal to maintain a steady flame. The simulations are performed for a 3D geometry with the following energy source distribution: …

Energy Efficiency Evaluation Of Blower Heater Non-Purge Compressed Air Dryers, Alexandra M. Botts

Graduate Theses, Dissertations, and Problem Reports (ETD)

There are several compressed air dryers available for industrial use including, refrigerant, desiccant, and membrane. This research focuses on twin tower regenerative closed loop desiccant dryers, specifically: blower heater non-purge (BHNP) with and without cooling water pumps, Compressed-air Heater Purge (CHP), Blower Heater Purge (BHP), and Pressure Swing Heaterless (PSH). These styles of dryers are used mainly in industries that require extremely dry air such as, food manufacturing, medical air, or sensitive technology manufacturers. The research was conducted by collecting and analyzing real time current draw data on air compressors and associated dryers at eight different facilities (13 compressor systems) …

Experimental And Numerical Study Of The Stirling Engine Robust Foil Regenerator, Koji Yanaga

Graduate Theses, Dissertations, and Problem Reports (ETD)

The regenerator is located between the heat accepter and the heat rejecter of the Stirling engine. It works as a thermal energy storage component in the engine. Most of the regenerators are made of woven screen or random fiber. However, the flow going through the woven screen or random fiber is similar to the cylinders in crossflow which has flow separation. To achieve higher engine efficiency, it is required to design a regenerator which has higher convective heat transfer, lower pressure drops. Therefore, a parallel channel regenerator called a robust foil regenerator was designed and manufactured.

In this study, a …

Dynamic Discrepancy Reduced Order Modeling For Fischer-Tropsch Synthesis Over Cobalt-Based Catalyst, Jose Miguel Bohorquez

Graduate Theses, Dissertations, and Problem Reports (ETD)

Advances in carbon capture techniques and demands in alternative fuel sources have increased over the past couple of decades. The Fischer-Tropsch Synthesis (FTS) provides a viable way to produce hydrocarbons from natural gas, coal, CO₂, or biomass. However, current comprehensive models for FTS encompass large number of reacting species, readsorption and conversion of primary products, surface intermediates, and coverage-dependent reaction rates. To accurately predict the products obtained through the process a reduced order model has been developed. By reducing the number of parameters of an existing comprehensive model, uncertainty is introduced. The uncertainty can be quantified by using …

A Biomimetic Approach To Controlling Restorative Robotics, Matthew T. Boots

Graduate Theses, Dissertations, and Problem Reports (ETD)

Movement is the only way a person can interact with the world around them. When trauma to the neuromuscular systems disrupts the control of movement, quality of life suffers. To restore limb functionality, active robotic interventions and/or rehabilitation are required. Unfortunately, the primary obstacle in a person’s recovery is the limited robustness of the human-machine interfaces. Current systems rely on control approaches that rely on the person to learn how the system works instead of the system being more intuitive and working with the person naturally. My research goal is to design intuitive control mechanisms based on biological processes termed …

Optimization Of Turbine Design In Wind Farms With Multiple Hub Heights, Using Exact Analytic Gradients And Structural Constraints, Andrew P.J. Stanley, Andrew Ning, Katherine Dykes

Faculty Publications

Wind farms are generally designed with turbines of all the same hub height. If wind farms were designed with turbines of different hub heights, wake interference between turbines could be reduced, lowering the cost of energy (COE). This paper demonstrates a method to optimize onshore wind farms with two different hub heights using exact, analytic gradients. Gradient-based optimization with exact gradients scales well with large problems and is preferable in this application over gradient-free methods. Our model consisted of the following: a version of the FLOw Redirection and Induction in Steady-State wake model that accommodated three- dimensional wakes and calculated …

Investigation Of Heat Exchanger Effectiveness Using A Surface Coating Technology, Allen Duffy

Graduate Theses, Dissertations, and Problem Reports (ETD)

Diesel engine manufacturers continue to improve engine performance through increased thermal efficiency and reduced regulated emissions. The aftercooler located between the turbocharger air outlet and intake manifold experiences a wide range of operating conditions. Improving the heat transfer characteristics in the aftercooler can lead towards improved engine performance through increased charge air density. A surface coating has been proposed to enhance the heat transfer characteristics for a marine-based application on the water - side of the heat exchanger. To evaluate the efficacy of the coating, the rate of heat transfer with and without the coating was quantified in a controlled …

Plasmonic Metamaterial For Structural Color Printing And Spontaneous Emission Control, Wei Wang

Doctoral Dissertations

”Plasmon polaritons or plasmons are a collective oscillation movement of free electrons in metal at optical frequencies. The frequency-dependent complex dielectric function makes the metal property at optical frequencies behave totally different with that at other spectral ranges with lower frequency such as infrared and microwaves. This novel property makes the so called plasmonics or nanoplasmonics a rapid growing research field over the past few years. Many innovative concepts and applications have been developed such as perfect absorber, structural color printing, and quantum emitter spontaneous emission enhancement.

In this dissertation two of the most important applications will be addressed. The …

Build Strategy Investigation Of Ti-6al-4v Produced Via A Hybrid Additive Manufacturing Process, Lei Yan

Doctoral Dissertations

“Till now, laser metal deposition (LMD) has been developed with the capability of near-net shape high-performance metal parts fabrication, especially complicated titanium alloys, nickel alloys, and aluminum alloys. However, LMD processed parts usually do not meet end-use requirements without post treatments. In-process part quality inspection and inner features machining are impossible within a single LMD process. Hybrid additive manufacturing (HAM), which integrates additive and subtractive manufacturing in one process, has been proposed to increase the feasibility of complex parts fabrication. This dissertation aims to improve the applications of Ti-6Al-4V parts fabricated via a HAM technique. The first research topic is …

Characterization Of Aerosols In An Underground Mine, Arash A. Habibi

Doctoral Dissertations

“Diesel-powered engines are a common source of submicron carbon-rich particles. Characterizing morphological and physical attributes of diesel agglomerates is therefore of great importance to be able to identify the source and improve removal technology. Size-segregated sampling was conducted in two phases of underground experiments. Scanning transmission electron microscopy and fast mobility particle sizers were used to determine the size distribution of agglomerates based on particle mobility and projected area diameter. Controlled zone sampling test results were used to determine the morphological characteristics of agglomerates for specific types of diesel equipment both with and without removal strategies. Changes in fractal dimension, …

Plenum-To-Plenum Heat Transfer Characteristics Under Natural Circulation In A Scaled-Down Prismatic Modular Reactor, Salman Mohammed Alshehri

Doctoral Dissertations

“Gas-cooled reactor (GCR) is being developed under the Next Generation Nuclear Plant Program (NGNP) in nuclear engineering studies. As the world searches for an energy source with high energy density, clean, abundant, and storable nature to avoid global warming issues, GCR seems to be a promising solution, particularly the possibility of producing hydrogen. Studying and developing the safety analysis and GCR technologies are required for the optimum design and safety of GCR system. Multiphase Reactors Engineering and Applications Laboratory (mReal) at Missouri University of Science and Technology (S&T) has developed a natural convection heat transfer test facility with one riser …

Computational Fluid Dynamics Modeling And Comparison Of Advanced Techniques For Heat Transfer Augmentation For Nuclear Applications, Salman Mohammed Alzahrani

Doctoral Dissertations

“Passive safety is the most important feature of NuScale’s reactor designs. Twist tape is one passive heat enhance heat technique. The present research investigated thermo-hydraulic characteristics of natural and forced convection of water under different configurations of twisted tape inserted in tube as well as NuScale rod bundles for uniform wall heat flux using computational fluid dynamics (CFD) using ANSYS Fluent 18.1. Results for twist tape inserted in tube under natural circulation showed that heat transfer enhanced and pressure drop increased to 28% and 102.8% over the plain tube respectively. Regularly spaced tapes, and different widths of the twisted tapes …

Volumetric Error Compensation For Industrial Robots And Machine Tools, Le Ma

Doctoral Dissertations

“A more efficient and increasingly popular volumetric error compensation method for machine tools is to compute compensation tables in axis space with tool tip volumetric measurements. However, machine tools have high-order geometric errors and some workspace is not reachable by measurement devices, the compensation method suffers a curve-fitting challenge, overfitting measurements in measured space and losing accuracy around and out of the measured space. Paper I presents a novel method that aims to uniformly interpolate and extrapolate the compensation tables throughout the entire workspace. By using a uniform constraint to bound the tool tip error slopes, an optimal model with …

Scaleable Nanomanufacturing Of Metasurfaces Using Microsphere Photolithography, Chuang Qu

Doctoral Dissertations

“The cost-effective manufacturing of metasurfaces over large areas is a critical issue that limits their implementations. Microsphere photolithography (MPL) uses a scalable self-assembled microsphere array as an optical element to focus collimated light to nanoscale photonic jets in a photoresist layer. This dissertation investigates the fabrication capabilities, process control, and potential applications of MPL. First, the MPL concept is applied to the fabrication of metasurfaces with engineered IR absorption (e.g. perfect absorption with multiband/broadband and wavelength/polarization dependences). Improving the patterning of the photoresist requires a fundamental understanding the photochemical photonic jet interactions. The dissertation presents a model of the MPL …

Solvent-Free Additive Manufacturing Of Electrodes For Li-Ion Batteries, Brandon Joshua Ludwig

Doctoral Dissertations

"A new Li-ion battery electrode manufacturing process using a solvent free additive manufacturing method has been developed. Li-ion battery electrodes consist of active material particles, a binder additive, and a conductive additive. Traditionally, Li-ion battery electrodes are manufacturing using the "slurry casting" technique. In this method, the electrode materials are mixed with a solvent to create a slurry. Electrodes fabricated in this method are readily implemented for small platforms, such as portable electronics. However, this method isn't as economically viable in large platforms due to high material and manufacturing costs. High material and manufacturing costs are mostly attributed to the …

Laser Welding Of Metallic Glass To Crystalline Metal In Laser-Foil-Printing Additive Manufacturing, Yingqi Li

Doctoral Dissertations

"The application of metallic glasses has been traditionally limited to parts with small dimensions and simple geometries, due to the requirement of fast cooling during the conventional process of casting. In addition, joining metallic glass to crystalline metal is of interest for many applications that require locally tailored functions and properties, but it is challenging. This research describes a promising additive manufacturing technology, i.e., laser-foil-printing, to make high-quality metallic glass parts with large dimensions and complex geometries and to fabricate multi-material components from metallic glass and crystalline metal. In this research, Zr_52.5Ti₅Al₁₀Ni_14.6Cu …

Deep Understanding Of Degradation In Lithium Ion Batteries Through Experimental And First-Principles Study, Yufang He

Doctoral Dissertations

"The growing interests in Lithium-ion Batteries (LIBs) have significantly accelerated the development of active materials. However, the key challenge is that electrode materials suffer from degradation, which include transition metal dissolution, solid electrolyte interphase (SEI) layer formation, and mechanical fracture. To address these issues, applying an ultrathin coating onto active materials via Atomic Layer Deposition (ALD) is an efficient way. Although numerious works have been done for active material performance improvement via ALD technology, the fundamental enhancement mechanisms of ALD coating on battery performance improvement are not yet known. Therefore, this dissertation consists of four papers, which focused on the …