Engineering Commons^™

A Novel Powder Factor Based Bench Blast Design Method For Large Surface Coal Mines, Andrew Clifford Blair

Doctoral Dissertations

"Large surface coal mines in Wyoming's Powder River Basin ship millions of tons of coal per annum, moving millions of cubic yards of overburden to mine the coal. Much of this volume is blasted in the form of benches, a common mining technique. Increases in production and scale of equipment in the past thirty-five years have created a paradigm shift for drill and blast personnel at these large surface mines, and the explosives industry has yet to create a blast design method specifically tailored for large surface coal mine bench blasting.

This research examines the typical scale of bench blasting …

Electromagnetic Compatibility In Power Inverter Design, Natalia Bondarenko

Doctoral Dissertations

"Power inverter systems generate significant electromagnetic emissions. Methods were studied to model these systems and to reduce their emissions. Three topics are presented in this dissertation.

Methods were developed to obtain simple SPICE models for complex systems which relate circuit components to physical geometry within the system. These models were derived using measurements or using partial element equivalent circuit (PEEC) and model size reduction techniques developed in this dissertation. Methods were proposed for developing a measurement-based model and were applied to a real power inverter/motor system. The model was used to identify system geometries responsible for critical resonances and to …

Characterization Of Bending Fatigue Mini-Specimens For Nuclear Materials, Ahmed Suliman R. Haidyrah

Doctoral Dissertations

"New materials with superior radiation and corrosion resistance are needed to improve the economy and performance of current nuclear reactors as well as future nuclear reactors. Measurement of mechanical properties of the material of equipment is required to estimate its safe operating life. Studying fatigue of irradiated specimens is challenging due to space limitation in research reactors (e.g. ATR). The mini-specimen bending fatigue (Krouse-type) of nuclear materials was used to study fatigue properties and compare the obtained results with that of reference data of full size specimen. These Krouse-type were made of austenitic SS304, SS316, HT9 ferritic martensitic steel, and …

System Integration Of Hydrogen Energy Technologies Using Renewable Energy Resources, Tarek A Mohammed Hamad

Doctoral Dissertations

"The objective of this work has two major tasks that investigation the use of CHHP system at the Missouri University of Science and Technology (Missouri S&T) campus and studying solid waste as renewable source of energy: current and future possibility in Libya. Task one has three major topics. In Topic I, Design of Combined Hydrogen, Heat and Power (CHHP) system for the campus using local resources and treated biogas can be used to generate CHHP using a Molten Carbonate Fuel Cell (MCFC). In Topic II, hydrogen recovery and cleaning system, Heat recovery and electric power usage, hydrogen compression, storage, and …

Design Studies Of Infrastructural Development For Applications Of Hydrogen Energy Technologies, Yousif M. H. Hamad

Doctoral Dissertations

"Countries around the world are trying to reduce their energy consumption, fossil fuel usage, and greenhouse gas (GHG) emissions. According to the International Energy Outlook 2012 released by the U.S. Energy Information Administration (EIA), the estimated fuel economy and greenhouse gas emissions standards proposed for light-duty vehicles for model years 2017-2025 has an increase of 44% in fuel economy and a reduction of 34% in GHG emissions. The use of alternative fuel vehicles and renewable energy sources are, therefore, inevitable toward achieving this goal. Biogas has untapped potential as an alternative energy source. This immediately available resource would allow countries …

Fusion Welding Of Diboride-Carbide Ceramic Composites, Derek Scott King

Doctoral Dissertations

"Plasma and pulsed plasma arc welding (PAW and PPAW) processes were used to fusion weld ZrB₂ containing 20 vol% ZrC. Varying welding parameters resulted in changes in weld pool shape and size, and the size of ZrB₂ grains within the fusion zone. For PAW processes that resulted in a keyhole fusion zone (full penetration), the arc to workpiece power transfer efficiency was estimated to be 2 grain lengths were observed to decrease between binary PAW FZs (~1 mm in length), and binary PPAW FZs (~0.8 mm in length), and an increasing aspect ratio for ZrB₂ grains in …

Analysis Of Ion Emitting Jet Structures During Ionic Liquid Electrospraying, Shawn W. Miller

Doctoral Dissertations

"The ionic liquid [Bmim][DCA] is a propellant candidate for a standalone electrospray thruster or a dual-mode propulsion system. Characterization of positive polarity ions produced by [Bmim][DCA] capillary emitters with a nominal extraction voltage of 2.0 kV within a quadrupole and time-of-flight mass spectrometers is presented along with the predictions of propulsion performance. Flow rates from 0.05 to 2.18 nL/s are used to investigate the impact variations in the flow parameter have on the electrospray plume. The retarding potential analysis reveals ions emitted from the capillary are formed below the emitter potential of 500 eV. Angular distributions indicate broadening of both …

Modeling Supply Chain Interdependent Critical Infrastructure Systems, Varun Ramachandran

Doctoral Dissertations

"While strategies for emergency response to large-scale disasters have been extensively studied, little has been done to map medium- to long-term strategies capable of restoring supply chain infrastructure systems and reconnecting such systems from a local urban area to national supply chain systems. This is, in part, because no comprehensive, data-driven model of supply chain networks exists. Without such models communities cannot re-establish the level of connectivity required for timely restoration of goods and services. This dissertation builds a model of supply chain interdependent critical infrastructure (SCICI) as a complex adaptive systems problem. It defines model elements, data needs/element, the …

Printed Circuit Board Power Distribution Network Modeling, Analysis And Design, And, Statistical Crosstalk Analysis For High Speed Digital Links, Ketan Shringarpure

Doctoral Dissertations

"High-speed digital systems are moving to higher data rates and smaller supply voltages as the scale of integration goes smaller. With the smaller bit periods and the smaller operating voltages, the tolerable timing and noise margins are reducing. There are many sources of disturbances contributing to the tolerance margins. These margins have to account for inter symbol interference (ISI), reflections, jitter, noise from power distribution networks (PDN) and crosstalk. An important task during the design phase of the system is to find and mitigate the noise from such sources. This thesis proposes modeling and analysis methodology to resolve some of …

Inclusion Engineering In Mn-Si De-Oxidized Steel For Thin-Strip Casting, Vivek Thapliyal

Doctoral Dissertations

"The focus of this research was to understand inclusion formation and evolution in Mn-Si de-oxidized steels used in thin-strip casting. Inclusions formation and evolution in ultra-low carbon low-alloyed steels were studied. Inclusion engineering can be used to remove or modify detrimental inclusions, which cause casting issues.

The first part of this study focused on inclusion formation as a result of ferro-alloy addition. De-oxidation reaction in steels are the primary source of the typical oxide inclusion formed in steel. For Mn-Si de-oxidized steels ferro-silicon and ferro-manganese are the two ferro-alloys used for de-oxidation. Inclusion formation and evolution during the early stages …

Numerical Study On Scaling Effects And Decoupled Network-Based Simulation Of Gaseous Explosion, Liang Wang

Doctoral Dissertations

"This research seeks to improve the prediction efficiency of gaseous explosions realized by numerical simulations in a full-scale underground network using a decoupled method. To provide quick predictions of overpressure distribution of methane explosions in underground airway networks, a two-section theory is employed. The explosion space is divided into a driver section and a blast-wave section. Governing equations including conservation of mass, momentum, and energy, together with chemical reaction and turbulence models are solved for the driver and the blast-wave sections using computational fluid dynamics (CFD) solver ANSYS Fluent (3D-based) and Flowmaster (1D-based) respectively. The three dimensional (3D) and one …

Iterative Ct Reconstruction From Few Projections For The Nondestructive Post Irradiation Examination Of Nuclear Fuel Assemblies, Muhammad Imran Khan Abir

Doctoral Dissertations

The core components (e.g. fuel assemblies, spacer grids, control rods) of the nuclear reactors encounter harsh environment due to high temperature, physical stress, and a tremendous level of radiation. The integrity of these elements is crucial for safe operation of the nuclear power plants. The Post Irradiation Examination (PIE) can reveal information about the integrity of the elements during normal operations and off‐normal events. Computed tomography (CT) is a tool for evaluating the structural integrity of elements non-destructively. CT requires many projections to be acquired from different view angles after which a mathematical algorithm is adopted for reconstruction. Obtaining many …

Advancements In Uncertainty Quantification With Stochastic Expansions Applied To Supersonic And Hypersonic Flows, Thomas Kelsey West Iv

Doctoral Dissertations

"The primary objective of this study was to develop improved methodologies for efficient and accurate uncertainty quantification with stochastic expansions and apply them to problems in supersonic and hypersonic flows. Methods introduced included approaches for efficient dimension reduction, sensitivity analysis, and sparse approximations. These methods and procedures were demonstrated on multiple stochastic models of hypersonic, planetary entry flows, which included high-fidelity, computational fluid dynamics models of radiative heating on the surface of hypersonic inflatable aerodynamic decelerators during Mars and Titan entry. For these stochastic problems, construction of an accurate surrogate model was achieved with as few as 10% of the …

Computational Intelligence Based Complex Adaptive System-Of-Systems Architecture Evolution Strategy, Siddharth Agarwal

Doctoral Dissertations

The dynamic planning for a system-of-systems (SoS) is a challenging endeavor. Large scale organizations and operations constantly face challenges to incorporate new systems and upgrade existing systems over a period of time under threats, constrained budget and uncertainty. It is therefore necessary for the program managers to be able to look at the future scenarios and critically assess the impact of technology and stakeholder changes. Managers and engineers are always looking for options that signify affordable acquisition selections and lessen the cycle time for early acquisition and new technology addition. This research helps in analyzing sequential decisions in an evolving …

Investigating New Accident Causation, Risk Assessment, And Mitigation Strategy Selection Tools In The Petroleum Industry, Mohammad A. Alkazimi

Doctoral Dissertations

"The inherent complexity of the processes and the volatile nature of petroleum products compel the petroleum industry to continually seek and develop tools and techniques to identify, evaluate, and mitigate potential risks that can negatively impact their process operations. Additionally, government agencies and nonprofit professional societies guide the petroleum industry with regulatory guidelines, standards, and recommended best practices. The industry and these agencies and societies work to improve operational management, to ensure safe working conditions, and to minimize risk of all kinds, so that if failures occur, damage is contained within tolerable limits (Health and Safety Executives, 2013).

The currently …

Computing And The Electrical Transport Properties Of Coupled Quantum Networks, Casey Andrew Cain

Doctoral Dissertations

In this dissertation a number of investigations were conducted on ballistic quantum networks in the mesoscopic range. In this regime, the wave nature of electron transport under the influence of transverse magnetic fields leads to interesting applications for digital logic and computing circuits. The work specifically looks at characterizing a few main areas that would be of interest to experimentalists who are working in nanostructure devices, and is organized as a series of papers. The first paper analyzes scaling relations and normal mode charge distributions for such circuits in both isolated and open (terminals attached) form. The second paper compares …

Reliability-Based Optimization Design Of Geosynthetic Reinforced Embankment Slopes, Michelle (Mingyan) Deng

Doctoral Dissertations

"This study examines the optimization design of geosynthetic reinforced embankment slopes (GRES) considering both economic benefits and technical safety requirements. In engineering design, cost is always a big concern. To minimize the cost, engineers tend to seek an optimal combination of design parameters among the considered alternatives while ensuring the optimal solution is safe. Reliability-based optimization (RBO) is such a technique that provides engineers the optimal design with the minimum cost while all technical design requirements are satisfied. The research goal of this study is to implement a mathematical formulation algorithm of the RBO technique in GRES design. To achieve …

Performance Analysis And Modelling Of Hybrid Photovoltaic-Thermal Solar Panels, Nicole C. Annis

Doctoral Dissertations

A photovoltaic-thermal (PVT) panel was constructed, tested, and modelled using both MATLAB and TRNSYS. During the experimental testing, which took place on the Missouri University of Science and Technology campus in Rolla, Missouri; two identical PVT panels were tested alongside two PV panels to gather an electrical baseline for comparison. Approximately 69 days’ worth of data were of data were collected during the summer of 2014. The PV electrical, PVT electrical, PVT thermal and PVT combined (electrical and thermal) efficiencies were 3.5-5.6%, 3.4-5.4%, 20.9-11.6%, and 24.3-17.0%, respectively.

A MATLAB program was developed using existing equations for one-dimensional, quasi-steady model of …

Shape Based Classification And Functional Forecast Of Traffic Flow Profiles, Wasim Kayani

Doctoral Dissertations

This dissertation proposes a methodology for traffic flow pattern analysis, its validation, and forecasting. The shape of the daily traffic flows are directly related to the commuter’s traffic behavior which merit analysis based on their shape characteristics. As a departure from the traditional approaches, this research proposed a methodology based on shape for traffic flow analysis. Specifically, Granulometric Size Distributions (GSDs) were used to achieve classification of daily traffic flow patterns. A mathematical morphology method was used that allows the clustering of shapes. The proposed methodology leads to discovery of interesting daily traffic phenomena such as five normal daily traffic …

Combustion And Pollutant Characteristics Of Ic Engines Fueled With Hydrogen And Diesel/Hydrogen Mixtures Using 3d Computations With Detailed Chemical Kinetics, Hassan A. Khairallah

Doctoral Dissertations

In order to develop design guidelines for optimum operations of internal combustion engines fueled with alternative fuels, a comprehensive understanding combustion behavior and the pollutant formation inside the cylinder are needed. The first part of this thesis aimed to numerically study the engine performance and in-cylinder pollutant formation in a spark ignition engine fueled with hydrogen. Advanced simulations were performed using multi- dimensional software AVL FIRE coupled with CHEMKIN. The detailed chemical reactions with 29 steps of hydrogen oxidation with additional nitrogen oxidation reactions were also employed. Formation rates of nitrogen oxides (NOx) within the engine were accurately predicted using …

Advanced Control Of Grid-Connected Multilevel Power Electronic Rectifiers, Sangin Lee

Doctoral Dissertations

"Multilevel power electronic converters have been gaining attention due to their ability to supply high amounts of power and to handle high voltage levels. In this dissertation, grid connected AC-DC rectifier application is investigated with different topologies and control scheme.

At first, neutral point clamped (NPC) rectifier is employed to transfer power from the grid to the load. The NPC rectifier has two capacitors in order to build multilevel output voltage. However, it causes voltage unbalancing problem. Therefore, the new method has been proposed to regulate each capacitor voltage at the same voltage level. Experimental results show that it is …

The Radiation Physics, Mitigation Approaches And Design Guidelines Of High-Speed Connectors And Cables Analyzed With Numerical Modeling, Analytical Formulation And Measurements, Jing Li

Doctoral Dissertations

The dissertation is composed of three papers, which cover the radiation and mitigation of high-speed connectors and cables analyzed with full wave simulation, numerical modeling, analytical formulation and measurements.

In the first paper, the radiation from the optical cage connector in the frequency range of 4-28 GHz is analyzed with validated full-wave simulation model and analytical formulas. The radiation from the optical cage connector is suppressed with absorbing materials, and the coupling path in optical link is verified, together with the optical cage and module enclosure.

In the second paper, radiation from antenna-mode current and TL-mode current is briefly reviewed …

Modelling Of Interconnects In 3dic Based On Layered Green Functions, Siming Pan

Doctoral Dissertations

As traditional CMOS scaling pace gradually slows down, three-dimensional (3D) integration offers another dimension of in the ”More-than-Moore” era. In this dissertation, a number of investigations were conducted to better model interconnects in 3D integrated circuit (IC), to evaluate electrical behavior including delay, power consumption, signal integrity (SI), and power integrity (PI) for 3D ICs. Partial Element Equivalent Circuit (PEEC) method with layered Green’s function is studied here, since it consumes less computational resources and provides better physical insight to model the interconnects in 3DIC for high-speed digital circuits. The work is organized as a series of papers. The first …

Describing Local Community Acceptance With Discrete Choice Theory For Enhanced Community Engagement, Sisi Que

Doctoral Dissertations

This research sought to facilitate improved community (stakeholder) analysis by providing further insight on the determinants of local community acceptance using discrete choice theory. Specifically, the goals were to: (1) Identify, classify, and verify the important project characteristics and key demographic factors which affect local community acceptance of a mining project; (2) Account for the large number of relevant factors inherent in discrete choice experiments for mining community acceptance evaluation; and (3) Examine discrete choice models to select the most appropriate model for mining community consultation. The research will test the hypotheses that various discrete choice models can describe the …

Investigation Of Robust Optimization And Evidence Theory With Stochastic Expansions For Aerospace Applications Under Mixed Uncertainty, Harsheel R. Shah

Doctoral Dissertations

One of the primary objectives of this research is to develop a method to model and propagate mixed (aleatory and epistemic) uncertainty in aerospace simulations using DSTE. In order to avoid excessive computational cost associated with large scale applications and the evaluation of Dempster Shafer structures, stochastic expansions are implemented for efficient UQ. The mixed UQ with DSTE approach was demonstrated on an analytical example and high fidelity computational fluid dynamics (CFD) study of transonic flow over a RAE 2822 airfoil.

Another objective is to devise a DSTE based performance assessment framework through the use of quantification of margins and …

Small Signal Modeling And Analysis Of Microgrid Systems, Md. Rasheduzzaman

Doctoral Dissertations

This dissertation focuses on small-signal modeling and analysis of inverter based microgrid systems. The proposed microgrid consists of two microsources placed on two different buses. The buses are connected using a distribution feeder with some impedance. The proposed microgrid can operate with the grid support, or without the grid support. When operated without the grid support, the standalone system’s microsources participate in controlling the system voltage and frequency. For a non-inertia source, such as the inverter, the load perturbations play an important role in system dynamics. In paper-I, such complex system was studied.

In the grid-tied mode, the microsources share …

Energy Management In Electric Vehicles: Development And Validation Of An Optimal Driving Strategy, Warren Santiago Vaz

Doctoral Dissertations

Electric vehicles (EVs) are a promising alternative energy mode of transportation for the future. However, due to the limited range and relatively long charging time, it is important to use the stored battery energy in the most optimal manner possible. Existing research has focused on improvements to the hardware or improvements to the energy management strategy (EMS). However, EV drivers may adopt a driving strategy that causes the EMS to operate the EV hardware in inefficient regimes just to fulfil the driver demand. The present study develops an optimal driving strategy to help an EV driver choose a driving strategy …

Development, Testing, And Analytical Modeling Of Fiber-Reinforced Polymer Bridge Deck Panels, Hesham R. Tuwair

Doctoral Dissertations

A fiber-reinforced, polyurethane foam core was developed, tested, and evaluated as a possible replacement for the costly honeycomb core that is currently used to manufacture fiber-reinforced polymer (FRP) bridge deck panels. Replacing these panels would reduce both initial production costs and construction times while also enhancing structural performance. Experimental, numerical, and analytical investigations were each conducted. Three different polyurethane foam (PU) configurations were used for the inner core during the study’s first phase. These configurations consisted of a high-density PU foam (Type 1), a gridwork of thin, interconnecting, glass fiber/resin webs that formed a bidirectional gridwork in-filled with a low-density …

Characterization Of Investment Shell Thermal Properties, Mingzhi Xu

Doctoral Dissertations

Thermal properties of investment casting shells have a great influence on the solidification of metal and thus control the properties of the cast product. Computational simulation requires accurate thermal properties to better represent the real process. Due to the porosity and meta-stable materials used in the investment shells, it is difficult to determine the real time thermal properties as a function of components and thermal processing history. Previous studies measured the thermal properties using a variety of methods, but very few results can be directly used in simulations due to lack of accuracy.

This research developed a new methodology that …

Pulsed Inductive Plasma Studies By Spectroscopy And Internal Probe Methods, Warner C. Meeks

Doctoral Dissertations

The broad effort of the Missouri Plasmoid Experiment is to elucidate the energy conversion processes in a pulsed inductive discharge due to the presence of plasma. The test article is a 440 to 490 kHz theta-pinch (or solenoidal) geometry coil with a stored energy of around 80 joules. In this work experimental hydrogen, helium, argon and xenon data at back-fill pressures of 10 to 100 mTorr (1.3 to 133.3 Pa) are obtained and interpreted. Spectral and internal probe studies were performed on MPX Mk.I and Mk.II devices, respectively. IR spectra were acquired in the Mk.I device for argon and xenon. …