Engineering Commons^™

Development Of An Interactive Robot For Overground Physical Human-Robot Interaction, Sambad Regmi

Doctoral Dissertations

"The overground interactive robots are potentially beneficial for humans in various areas, such as overground rehabilitation therapies and robotic interactive assistance. However, it is unclear what the expectations and challenges are for a robot to be physically interactive with a human during overground tasks, such as a robot helping an older adult walk. To develop such a robot, one must first build a clear understanding of how the human motor intent is communicated when interacting with another agent. Specifically, how do humans understand the leader’s intention when being led?

Based on previous works, we hypothesized that humans modulate their arm …

Sustainable Face Milling Of Inconel 718 Using Mql And Nanofluids Mql With Vegetable Oil As Base Fluid, Theodore Obumselu Nwoguh

Doctoral Dissertations

"Extreme heat and friction are generated in machining difficult-to-cut metals used in aerospace and nuclear industries leading to poor machinability (high cutting forces, rapid tool wear, shorter tool life, and poor surface integrity). Conventional flood coolant (CEC) used in industry is environmentally unfriendly, hazardous to operators, and unsustainable. These problems motivated this research, which can be mitigated with the use of effective biodegradable cutting fluids, appropriate cutting conditions, and lubrication/cooling strategies. This research provides a sustainable and environmentally friendly replacement to CEC. Firstly, the research characterized three vegetable oils (High Oleic Soybean Oil (HOSO), Low Oleic Soybean Oil (LOSO), and …

Development And Testing Of A New Air-Assisted Flare System For Low Flow Conditions, Hayder Alhameedi

Doctoral Dissertations

"Flare systems provide a safe, efficient, and reliable way to treat unwanted flammable gases that come from relief devices of various chemical processing equipment to ensure the safety of personnel and equipment. Flare systems are classified according to the assist media type as non-assisted (utility), steam-, air-, and pressure-assisted flares. The assist medium enhances mixing between flare gases and surrounding air and induces more air into the combustion zone. An air-assisted flare system is the preferred flare type in regions where steam is unavailable or is costly to supply or ambient temperatures are too low. The environmental protection agency (EPA) …

Advanced Materials And Processes For Gas Separation And Storage Applications, Qasim Mohammed Al-Naddaf

Doctoral Dissertations

"Transition to a clean, renewable energy future requires departure from thermally driven separation processes. In that regard, development of new materials that exhibit high adsorption capacity and selectivity, fast kinetics, and long-term durability under multicomponent conditions is becoming attractive for the applications in clean energy. Moreover, novel sorbents and separation systems that can store gases at normal conditions offer a promising approach for stationary or onboard gas storage. Due to the limitations on the surface area and biding energy restrict commercial materials effectiveness as a potential adsorption and storage material. There is significant interest in the properties of hybrid materials …

Corrosion Resistance Performance Investigation Of Mild Steel Bar Coated With Magnesium Phosphate Cement Paste, Fan Zhang

Doctoral Dissertations

"In this research study, the anti-corrosion mechanism of reinforcement embedded in magnesium potassium phosphate cement (MKPC) is explored. In addition, one type of additives, metakaolin, and one type of retarder, boric acid, are employed in MKPC to modify its properties in order to further investigate corrosion resistance and to achieve mass-production coating reinforcement at the work site. This coating method may be practical for some underwater construction and some traditional reinforcement concrete structures to reduce the reinforcement corrosion rate and to eventually extend service life in both repair and new construction applications.

By comparing the electrochemical properties of bare ribbed …

Use Of Cellular Concrete For Air Convection Embankment To Protect Permafrost Foundation In Cold Regions, Hanli Wu

Doctoral Dissertations

"Crushed-rock air convection embankment (ACE) has been used to mitigate thaw settlement, and pavement distresses caused by climatic extremes in permafrost regions for over three decades. However, the desired crushed rocks needed for ACE are not readily available in many areas of interior Alaska. Burdened by the need to ship suitable rocks to remote locations, the cost of constructing an ACE is often prohibitively high, which prevents its wide use in Alaska. An existing cementitious material, cellular concrete, may provide the solution.

This study intends to systematically characterize the heat transfer patterns of ACE and identify the performance benefits of …

Investigating The Interaction Between The Recycled Components And The Asphalt Binders, Plant, Lab, And Field Mixes, Eslam Deef-Allah

Doctoral Dissertations

"Modifying asphalt binders and mixes with recycled components is common practice due to their environmental and economic merits. Literature has indicated that different recycled components interact with (blend with) asphalt differently, ranging from no blending, partial blending, or full blending. The degree of blending between recycled components and virgin asphalt binders (VABs) and the exchanged components impact the performance of modified asphalt binders. However, the nature of the interaction process between the recycled components and the VABs is not fully understood. The primary objective of this study was to explore the interactions between recycled components and VABs. By understanding the …

Theoretical Determination Of The Yield Curve For Unsaturated Soils, Sara Fayek

Doctoral Dissertations

"An important step to developing a good understanding of the behavior of unsaturated soils is to adopt a formal and simple constitutive framework and to conduct high-quality and short-time experiments. Barcelona Basic Model (BBM) was the first elastoplastic constitutive model for unsaturated soils. The yield curve, which separates the elastic region from the elastoplastic region, is an important aspect of constitutive modeling for unsaturated soils. Most concepts for unsaturated soils were developed based upon the results from suction-controlled triaxial (SCTX) tests. Though, the SCTX tests on unsaturated soils are costly, time-consuming, and laborious, and their results are questionable. This study …

Accuracy Improvement Of Cable Harness Modeling & Analytical Modeling Of Multi-Reflections In High-Speed Signal Channels, Muqi Ouyang

Doctoral Dissertations

"Cable harnesses are widely used in modern vehicles to power electric systems locating at different locations throughout the vehicle and to establish signal channels for data communications between these systems. Generally, a cable harness consists of multiple wires and its geometry can be very complicated, making full-wave modeling and simulation approaches computational resource-intensive. To cut down the computational effort, the hybrid multiconductor transmission-line (MTL) method has been developed, and the generalized MTL (GMTL) method and the multiple scattering (MS) method have been developed to improve the accuracy of the hybrid MTL method. In this research, the convergence issue in the …

Multifunctional Behaviors Of Two-Dimensional Materials And Their Composites, Yanxiao Li

Doctoral Dissertations

"Two-dimensional (2D) materials, including graphene, transition metal carbides or nitrides (TMC/Ns), have rich surface chemistry, superb electrical and mechanical properties. These unique properties make them ideal for multifunctional devices. Among them, we focused on graphene and TMC/Ns (i.e., MXenes), as well as their composites. Unlike the well-known graphene, MXenes, are relatively new and typically synthesized by the selective etching of the “A” layers from the layered carbides and /or nitrides known as MAX phases, which introduce MXenes with rich terminal groups (e.g. -O-, -OH, -F).

During my Ph.D. study, firstly, the adhesive and frictional behaviors, which are related to successful …

Using Computational Methods To Optimize High Heat Flux Component Thermal Performance In Magnetic Confinement Fusion Reactor Research, Monica Gehrig

Doctoral Dissertations

"Heat transfer enhancement by means of internally modified geometries in tubes and channels is an important mechanism to improve the survivability of components in extreme high-heat flux environments. Various features such as ribs and fins are studied using computational fluid dynamics in both uniform and one-sided heating in tubes and rectangular channels respectively to determine the most effective geometries across a variety of different flow and heating conditions. This work examines heat transfer enhancement and rib geometry optimization to support experimental research for nuclear fusion applications. The project begins by designing and analyzing test sections supporting a helium flow loop …

Development And Application Of Ensemble Machine Learning Algorithms To Enable A Priori, High-Fidelity, And Prompt Predictions And Optimizations Of Complex Materials And Systems, Taihao Han

Doctoral Dissertations

"Complex materials consisting of multiple chemical components/phases have been widely used in different engineering applications that have strict criteria. To optimize the mixture design of complex materials, researchers invest enormous resources in cumbersome experiments. However, due to substantial variations in precursors and processing techniques, it has been challenging to develop theoretical frameworks (i.e., empirical models) that could produce reliable predictions of properties of complex materials. In recent years, scientists have harnessed the power of machine learning (ML) and “Big” data to uncover the underlying mixture design-property correlations and produce high-fidelity predictions of properties of complex materials. The ML models autonomously …

Mobility Analysis And Topology Synthesis Of Compliant Mechanism Using Compliance Number And Pseudo-Rigid-Body Model (Prbm), Pratheek Bagivalu Prasanna

Doctoral Dissertations

"Establishing and understanding the kinematic properties of a compliant mechanism has been a relatively recent endeavor and has proved to be a challenging task. A concept of compliance number was offered earlier; the development of terminologies was emphasized that aided in its determination. It also hypothesized that the compliance number (C) and stored strain energy, or mode shapes, are strongly correlated. This compliance number (C) concept is revisited, and a more lucid interpretation of its significance is provided. A fundamental understanding of the concept of deformation mode shapes in compliant mechanisms is formalized using two distinct categories: (i) segmental and …

Sensitivity Of The Two-Fluid Model To Constitutive Correlations For Large Diameter Pipes, Alexander Lee Swearingen

Doctoral Dissertations

"Multiphase flows are a significant factor in nuclear reactor operations. In order to understand this behavior in reactor systems, system analysis codes are used to simulate reactor conditions. Due to the nature of the nuclear industry, simulations predicting the void development in the core are required to be highly accurate. This work evaluated the sensitivity of the void fraction and interfacial area concentration predictions to changes in correlations used to calculate three parameters that are used to complete the interfacial drag calculation. The three parameters evaluated were drift-flux, void fraction covariance, and interfacial area concentration. The change in drift-flux correlation …

Characterizing And Modeling Methods For Power Converters, Anfeng Huang

Doctoral Dissertations

“Stable power delivery is becoming increasingly important in modern electronic devices, especially in applications with stringent requirements of its form factor. With the evolution of technology, the switching frequency in a power converter is pushed to a higher frequency range, e.g., several MHz or even higher, to decrease its size. However, the loss generated in the converter increases drastically due to the high switching frequency. In addition, a wide-band feedback controller is required to accommodate the high switching frequency in the converter. We focus on the characterization or modeling of the feedback control circuits and critical components in a switching …

Characterization Of High Cycle Fatigue And Laser-Aided Machining And Polishing Of Additively Manufactured Materials, Mohammad Masud Parvez

Doctoral Dissertations

“Additive manufacturing (AM) and laser-aided machining and polishing (LAMP) of materials are emerging manufacturing processes both for research and industrial sectors. The AM process can manufacture near-net-shape parts with complex geometries. Meanwhile, the LAMP process integrated with an AM system offers a high processing rate, minimum heat-affected zone, and easily adjustable process parameters during machining and polishing. In mechanical properties characterization of AM metals and alloys, fatigue is a vitally important test method to understand the behavior of materials in cycling loading and unloading circumstances since most mechanical failures of structures are due to fatigue. To characterize AM metal fatigue …

Determining Thermal Properties Via Parameter Estimation Of A One-Dimensional, Analytical Model, Lauren B. Tomanek

Doctoral Dissertations

“In thermal applications, thermal conductivity is used to predict how well a material conducts heat. The accuracy of the magnitude of the thermal conductivity becomes increasingly essential to optimize part geometry. Thermal conductivity can vary significantly from the nominal value due to post-processing. The ASTM standards available to measure thermal conductivity are challenging to reproduce because of the insulated and prescribed temperature boundary conditions that are needed. The research introduces two new methods for estimating thermal conductivity that deliver the same accuracy as the existing ASTM standards and are easier to implement. The methods account for losses in the heating …

A Three-Dimensional Fully Coupled Hydro-Mechanical Elasto-Plastic Model For Unsaturated Soils With Consideration Of Hysteresis Behavior, Beshoy Sami Moussa Riad

Doctoral Dissertations

"Unsaturated soils are often used as a construction material in transportation infrastructures; in which it is subjected to cyclic traffic loadings and/or seasonal wetting-drying cycles. While mechanical hysteresis is a common feature of soils in general, hydraulic hysteresis is associated with unsaturated soils. Most existing constitutive models paid limited attention to the mechanical and hydraulic hysteresis behavior of unsaturated soils. This research presents a three-dimensional model for unsaturated soils and a chemo mechanical model for saturated soils. The unsaturated soils’ model has the following characteristic features: (a) the hydraulic and mechanical behaviors are fully coupled under 3D conditions; (b) it …

Strategies To Improve Shrinkage Resistance Of Cement-Based Materials For Extrusion-Based 3d Printing, Kavya Vallurupalli

Doctoral Dissertations

"The main objective of this study is to develop new generation of shrinkage-resistant 3D printable mortar mixtures. To this end, the research work was carried out to: i) identify key material and processing parameters that affect printability; ii) investigate the influence of water-to-cement ratio, superplasticizer dosage, and welan gum content on mortar printability; iii) propose a “printability window” where rheological properties and desorptivity can secure successful printing; iv) investigate effect of shrinkage mitigation materials (expansive agent (EA), pre-saturated lightweight sand (LWS), superabsorbent polymers (SAP), and shrinkage reducing admixture) on printability and shrinkage performance of mortar; and v) evaluate the effect …

Design Methods For Pressure Relief Well Systems At Dams And Levees, Andrew Keffer

Doctoral Dissertations

"Flood risk reduction structures such as dams and levees are important systems that provide significant benefits to the nation. Relief wells reduce the substratum water pressures that can compromise them via internal erosion. The U.S. Army Corps of Engineers (USACE) analytical method to design relief well systems by calculating discharge and excess head along an infinite line of wells was developed from the 1930s – 1950s. The research presented here increases our understanding of the method’s history and uses analytical and numerical models to improve current infinite and finite well system design practices. The historical development of this method was …

Oxidation Of Silicon Carbide And Graphite For High Temperature Gas-Cooled Reactor Applications, Adam Thomas Bratten

Doctoral Dissertations

"This research focuses on the oxidation behavior of silicon carbide and matrix grade graphite, specifically as it pertains to accident scenarios in Gen IV thermal spectrum high temperature gas cooled nuclear reactors. It is imperative to understand the oxidation behavior of such materials to predict their response to off-normal environments and certify their accident tolerance to implement Gen IV reactors. The onset of oxidation temperature of matrix graphite was found to have a strong dependence on the microstructure, and therefore processing parameters, of the materials. The A3-3 type grade contained regions of partially graphitized carbon that were more disordered and …

Surface Modification To Improve The Electrochemical Performance Of Cathode Materials For Lithium-Ion Batteries And Sodium-Ion Batteries, Han Yu

Doctoral Dissertations

"The specific capacity of active materials as well as their cycling stability are the main limiting factors for the performance of lithium-ion batteries (LIBs) and sodium-ion batteries (SIB). Atomic layer deposition (ALD) is considered as a promising surface modification method to enhance the electrochemical performance of active materials for LIBs and SIBs.

In this research, we are committed to using ALD to modify the cathode materials of LIB, by coating different films on the surface of different cathode materials and constructing a stable and favorable interface layer for lithium-ion transport, so that we can protect the active materials from the …

The Effect Of Mass Transport On Deposit Quality In Copper Electrowinning, Joseph Bauer

Doctoral Dissertations

"Roughness and nodulation of copper electrodeposits depend strongly on mass transfer conditions of copper ions to the electrode surface. Mass transfer properties in electrowinning electrolytes were first characterized. The effective diffusivity of cupric ion was measured with a rotating disk electrode in CuSO₄-H₂SO₄ electrolytes at temperatures relevant to electrowinning, with and without additives. Adding 20 mg L^-1 of chloride ion increased the measured diffusion coefficient, but commercial smoothing additives had little effect. An empirical formula to predict cupric diffusivity was generated for later use in mass transport modeling.

Boundary layer thickness information for commercial …

Influences Of The Internal Residual On Combustion Instabilities In The Misfire And Partial Burn Regimes Of A Dilute Spark-Ignition Engine, Rachel Inez Stiffler

Doctoral Dissertations

"Dilution in spark-ignition (SI) engines can improve fuel consumption and reduce emissions; however, increased levels of dilution either from excess oxidizer or exhaust gas recirculation (EGR) causes combustion to become more strained and cycle-to-cycle variations increase. At high levels of dilution incomplete combustion events (i.e. misfires and partial burns) start to occur, which cause combustion instabilities and eventually a dilute limit is reached. It is known the combustion instabilities seen are primarily due to the feed-forward mechanism present in the residual gases, but it is still unknown what about the residual is influencing the dynamics under high levels of dilution …

Source Reconstruction In Near Field Scanning For Rfi Application, Hosseien Rezaei

Doctoral Dissertations

"This research is divided into three major topics. The first topic, mechanical magnetic field generator for communication in the ULF range, is discussed in the first paper. The second topic, source reconstruction in near field scanning for RFI application, is discussed over the course of two papers. The third topic, analysis of imbalanced 2 or 3 Wire VHF LISN, is discussed in the last two papers.

In the first topic, the possibility to use a mechanical system (a rotating magnet) as a source (generator or antenna combined) of the ULF magnetic field is investigated. Ultralow frequency (ULF) communication systems have …

Experimental And Numerical Studies Of Novel Thermal Energy Storage Materials For Applications In Concrete And Energy Storage Systems, Wenyu Liao

Doctoral Dissertations

In this work, several types of novel thermal energy storage (TES) materials and composites are explored, and a series of numerical simulation models and experimental protocols are developed to evaluate the potentials of these materials to be applied in concrete, pavement, and thermal energy storage systems.

The first two types of novel TES materials/composites are at the micro-scale, which use micro diatomite (DE) and cenosphere (Ceno) as carriers of phase change material (PCM), respectively. The third type of novel TES material is at the macro-scale, utilizing lightweight sand (LWS) and lightweight coarse aggregate as carriers to load PCM. The last …

Catalytic Carbon Dioxide Hydrogenation To Methanol/Dimethyl Ether Over Copper-Based Catalysts, Xiao Fan

Doctoral Dissertations

Direct synthesis of dimethyl ether (DME) via CO₂ hydrogenation has received great attention, owing to the global warming caused by CO₂ emission and increasing energy demand worldwide. In this works, three major aspects of bifunctional catalysts development were studied: (1) investigation of the roles of interaction in the CuO-ZnO-ZrO₂-Al₂O₃/HZSM-5 bifunctional catalysts, (2) deactivation and regeneration of CuO-ZnO-ZrO₂-Al₂O₃ with different zeolitic catalysts for one-step CO₂ hydrogenation to dimethyl ether, and (3) study on the enhancement of activity and stability of CZZA/HZSM-5 bifunctional catalysts via the introduction of …

The Implementation Of Energy Sharing Using A System Of Systems Approach, Julia Morgan

Doctoral Dissertations

"There is an increasing demand for renewable energy and consumers need more procurement options to meet their needs. Energy sharing provides a peer-to-peer (P2P) marketplace where prosumer electricity is redistributed to fellow energy-sharing community participants. This redistribution of prosumer electricity provides consumers with additional electricity suppliers, while also decreasing the load on the utility company. Though significant progress has been made regarding research and implementation of energy sharing, there is still room for growth when evaluating energy-sharing communities and defining appropriate community coordination based on end-user needs. The first contribution in this work identified nine characteristics of energy-sharing communities as …

Quantum Inspired Concepts In Decision Making, Qizi Zhang

Doctoral Dissertations

"In this study, several new applications of quantum-inspired techniques are presented to advance the state of the art in decision making. In the first part, a quantum boost scheme for multiple-model filters based on extended Grover’s algorithm is presented for fault detection and parameter estimation. The quantum boost scheme accelerates the convergence of the posterior probabilities in the multiple-model filter. Stability proofs for the quantum boost scheme is presented and its performance is analyzed using benchmark examples. In the second part, the scope of application is extended to modeling human decision making. The open quantum system cognition model is applied …

Using Similitude Theory And Discrete Element Modeling To Understand The Effects Of Digging Parameters On Excavation Performance For Rubber Tire Loaders, Atta Ur Rehman

Doctoral Dissertations

"The large sizes of mining equipment pose challenges for analysis using experiments or simulation. While scaled physical and simulation models can address this challenge, no previous work has explored how similitude theory and modeling can provide valid analysis of large equipment such as rubber tire loaders. The objective of this research was to apply similitude theory and discrete element modeling (DEM) to study the effect of different digging parameters on the penetration and the draft on the buckets of rubber tire loaders. The work sought to (1) test the hypothesis that the geometry of a rubber tire loader bucket and …