Digital Commons Network^™

A Comparative Study Of Capacitor Voltage Balancing Techniques For Flying Capacitor Multi-Level Power Electronic Converters, Vennela Yadhati

Masters Theses

"With the advent of multilevel converters for high power applications in industry, a need to develop simpler topologies and control techniques has arisen. The flying capacitor multilevel inverter (FCMLI) is one such topology which is gaining popularity in recent years with many advantages such as extra ride-through capabilities because of the capacitor storage, redundancy in switching states, low common mode voltage ratio, improved power quality, etc. In this thesis, different basic multilevel converter topologies and their advantages and applications are discussed. The thesis mainly focuses on single-phase five-level FCMLI topology. Different control techniques for capacitor voltage regulation like staircase modulation, …

Evaluation Of Liquefaction-Induced Lateral Spreading In The Midwest, Kermit Nathanial Applegate

Masters Theses

"The Central United States is home to several seismically active regions: the Wabash Valley Seismic Zone, the South Central Illinois Seismic Zone, and the New Madrid Seismic Zone. All three of these regions are capable of inducing large ground motion throughout the Mississippi Valley and along the eastern border of Missouri. This has been supported by many paleoseismic studies conducted throughout the region, which have identified numerous instances of liquefaction phenomena. The fluvial deposition process associated with the Mississippi river valley makes it a prime location for possible liquefaction and lateral spreading effects. However, there are few studies pertaining to …

Innovative Concrete Bridging Systems For Pedestrian Bridges: Implementation And Monitoring, Kurt Edward Bloch

Masters Theses

"Two precast, prestressed pedestrian bridges were designed for rapid construction in Rolla, MO, utilizing high-strength concrete (HSC) and high-strength self-consolidating concrete (HS-SCC) with a target 28 day compressive strength of 68.9 MPa (10,000 psi) and release compressive strength of 24.1 MPa (3,500 psi). In addition, a glass fiber reinforced polymer (GFRP) bar reinforced deck panel system was utilized in one of the two deck panels on each bridge.

Material properties were tested for compression, elastic modulus, modulus of rupture, splitting tensile strength, creep, and shrinkage following ASTM standards. Instrumentation systems within the spandrel beams and precast deck panels were implemented …

Control And Applications Of Double Input Dc-Dc Power Electronic Converters, Venkata Anand Kishore Prabhala

Masters Theses

"Multi-input power electronic converters (MIPEC) are increasingly gaining interest in the fields of renewable energy systems and hybrid electric vehicles (HEV). The main advantage of MIPECs is their ability to interface several energy sources and storage devices using a single power conversion stage. Therefore, they provide simpler control and smaller parts count. In this thesis, various aspects of the utilization of double-input (DI) converters in solar and HEV applications are explored. For instance, a DI buckboost topology is proposed for a photovoltaic (PV)/battery energy system. The converter is controlled in a way that maximum power is drawn from the PV …

Implementing Frequency Regulation Capability In A Solar Photovoltaic Power Plant, Venkata Ajay Kumar Pappu

Masters Theses

"Photovoltaic power plants pose some challenges when integrated with the power grid. Today's PV plants focus on extracting the maximum power from the arrays. This makes the PV system unavailable for helping in regulating the grid frequency as compared to conventional synchronous generators. A new technique for tracking a pseudo-maximum power point for creating power reserve is presented. This will help provide fast response in injecting power to respond to rapid load changes in a manner analogous to the inertia of a rotating machine. This helps in contributing toward frequency regulation. This thesis examines the implementation of a two stage …

Residential Energy Monitoring: Missouri S&T Solar Village Development, Christopher David Wright

Masters Theses

"As energy costs are rising, public and private sector groups are searching for improved energy efficiency technology. Research tools for predicting residential energy usage are lagging behind commercial developments. Missouri S&T has a unique and strong opportunity to strengthen its involvement in the development of residential energy research and knowledge. The S&T Solar Village, a collection of homes designed for energy efficiency and renewable energy, is poised to support this research. This thesis develops a design for residential energy evaluation and data collection of the four solar homes in the Village. The energy evaluation system identifies over 300 sensors and …

Understanding Corrosion Of Ni₃(Si,Nb) Alloys In Hot Sulfuric Acid, Jen-Hsien Hsu

Doctoral Dissertations

"The Sulfur-Iodine thermochemical cycle has been proposed as a method for producing large quantities of hydrogen gas from water. However, the extreme operating environments involved limit the possible materials for construction.

Through proper heat treatment and composition control, the modified patented Ni₃(Si,Nb) alloy keeps high temperature strength to greater than 750⁰C and can be deformed by cold rolling more than 50% using multiple passes and intermediate anneals. The corrosion resistance is reproducible and maintains less than 5 mpy for a broad range of boiling sulfuric acid concentrations, including 70 wt%.

In the boiling 70 wt% sulfuric acid corrosion tests, kinetic …

Ceramic Dielectrics For High Energy Density Capacity Application, Sheng Chao

Doctoral Dissertations

"The objective of this dissertation is to investigate the relationship between the processing parameters, microstructural development, defect chemistry and electrical properties of titanium oxide (TiO₂) dielectrics for high energy density capacitor applications. The effects of aliovalent dopants on the dielectric properties of TiO₂ ceramics were investigated, aiming to further improve the desired dielectric properties especially at elevated temperatures (up to 200°C). Due to the segregation of acceptor type impurities in the starting powders, space charge polarization took place in TiO₂ ceramics with relative large grain size (>̲500nm), leading to high dielectric loss and low energy storage efficiency. Increased ratio …

The Marketing Value Of Graduate Certificate Programs In Higher Education: A Strategic Assessment, Susmitha Akula

Masters Theses

"The last five years have seen a significant increase in the popularity of non degree graduate certificates. This increase has raised questions about the value of graduate certificate programs from the perspective of students, alumni and industry employers. Do certificate programs provide real world skills and knowledge valuable to industry? Do they serve as effective recruiting tools for the university? Do they provide opportunities for students to meet their professional goals in terms of salary increase, promotions, and the like? The present research is specifically aimed at answering these questions. Surveys that assess perceptions of value of graduate certificates to …

Freeze Extrusion Fabrication Of 13-93 Bioactive Glass Scaffolds For Bone Repair, Nikhil D. Doiphode

Masters Theses

"We have investigated Freeze Extrusion Fabrication (FEF) of 13-93 bioactive glass to fabricate three dimensional scaffolds for bone tissue engineering. Bioactive glass paste was prepared for consistent extrusion through micro-nozzle and controlled porosity scaffolds were fabricated using additive manufacturing FEF. CAD models were prepared for different scaffold designs and computer controlled layer-by-layer deposition of pseudoplastic paste was carried out to in accordance. Liquid nitrogen assisted freezing of pastes was used for the consolidation of deposited layers. Post processing binder burnout and sintering schedules were designed for evaporation of organic binder and densification of glass. Sintering shrinkage was measured, and X-ray …

Evaluation Of Variable Speed Limits Using A Genetic Algorithm Approach To Calibrate A Vissim Model, Brian Joseph Schaefer

Masters Theses

"The variable speed limit (VSL) system has been adopted on more and more roadways across the globe as an engineering tool for controlling traffic flow, particularly during congestion situations. An important and fundamental question raised among traffic engineers is: Are the costs of installing and operating variable speed limits really justified? In order to answer this question, this thesis measures the effectiveness of the VSL system applying the VISSIM microscopic simulation model to a non-recurrent congestion situation. For the analysis, a section of interstate was modeled in VISSIM and calibrated so that the simulated results closely reproduce the observed data …

Microalgal Bioremediation Of Nutrients In Wastewater And Carbon Dioxide In Flue Gas, Anand Murali Narasimhan

Masters Theses

"Microalgae are potential biofuel feedstocks that can provide solutions to the twin challenges of energy security and environmental pollution. They have great potential for the removal of excess nitrogen and phosphorus from wastewater including the farm runoff. They can capture carbon dioxide in the flue gas from coal fired power plants thereby reducing greenhouse gas and also producing algal biomass, which can be converted into biofuel. In this study, the nutrient consumption of Scenedesmus algae was investigated in a batch culture and the biomass yield was determined. Algae were able to utilize carbon in the form of soluble carbonates which …

Application Of Life Cycle Assessment To Estimate Environmental Impacts Of Surface Coal Mining, Ofentse Ditsele

Masters Theses

"Coal plays an important role in meeting the energy needs of the World. Given its abundance and low cost, its use is bound to increase with the growing energy demand. Despite its importance, there are concerns over coal's environmental burdens. In order to extract and use coal in a sustainable manner, sustainability assessment has to be comprehensive. Life Cycle Assessment (LCA) provides systematic and quantifiable measures for assessing environmental burdens of products and processes. Extensive LCA work has been done on coal use, particularly in electricity generation, but, the coal mining stage has been neglected, for the most part. This …

Thermodynamic Based Modeling For Nonlinear Control Of Combustion Phasing In Hcci Engines, Joshua Bradley Bettis

Masters Theses

"Low temperature combustion modes, such as Homogeneous Charge Compression Ignition (HCCI), represent a promising means to increase the efficiency and significantly reduce the emissions of internal combustion engines. Implementation and control are difficult, however, due to the lack of an external combustion trigger. This thesis outlines a nonlinear control-oriented model of a single cylinder HCCI engine, which is physically based on a five state thermodynamic cycle. This model is aimed at capturing the behavior of an engine which utilizes fully vaporized gasoline-type fuels, exhaust gas recirculation and intake air heating in order to achieve HCCI operation. The onset of combustion, …

Graded-Index Fiber Collimator Enhanced Extrinsic Fabry-Perot Interferometer, Yinan Zhang

Masters Theses

"In this thesis, we studied a fringe visibility enhanced extrinsic Fabry-Perot interferometer (EFPI) by fusion splicing a quarter-pitch graded-index fiber (GIF) fiber to the lead-in single-mode fiber (SMF). The performance of the GIF collimator is theoretically analyzed using a ray matrix model and experimentally verified through beam divergence angle measurements. The fringe visibility of the GIF-collimated EFPI is measured as a function of the cavity length and compared with that of a regular SMF-EFPI. At the cavity length of 500µm, the fringe visibility of the GIF-EFPI is 0.8 while that of the SMF-EFPI is only 0.2. The visibility enhanced GIF-EFPI …

Reverberation Reduction In A Room For Multiple Positions, Raghavendra Ravikumar

Masters Theses

"Reverberation in a room occurs when the direct path sound from a sound source undergoes multiple reflections from the walls of the room before reaching the listener. An impulse response of the room can be measured called the room impulse response (RIR) which captures the effects of the room. This can be represented digitally on a computer. A filter is designed to cancel the effects of the room using the information in the room impulse response. This filter is called an equalization filter and is usually placed between the source signal and loudspeaker to perform the equalization. The RIR changes …

Sensor Data-Based Decision Making, Ahmet Soylemezoglu

Doctoral Dissertations

"Increasing globalization and growing industrial system complexity has amplified the interest in the use of information provided by sensors as a means of improving overall manufacturing system performance and maintainability. However, utilization of sensors can only be effective if the real-time data can be integrated into the necessary business processes, such as production planning, scheduling and execution systems. This integration requires the development of intelligent decision making models that can effectively process the sensor data into information and suggest appropriate actions. To be able to improve the performance of a system, the health of the system also needs to be …

A Hybrid Problem-Based And Just-In-Time Inductive Teaching Method For Failure Analysis Instruction, Ryan Michael Arlitt

Masters Theses

"When engineers retire, they take their expert knowledge with them. Preservation of this expert knowledge in a usable form is beneficial for the advancement of any engineering field. Risk in Early Design (RED) is one method for preserving expert risk analysis knowledge. The first purpose of this paper is to examine the usability of RED when incorporated with a hybrid problem-based and just-in-time inductive teaching method for failure analysis instruction. The second purpose of this paper is to propose and perform steps toward verification and validation of the RED methodology and implementation. Evaluation metrics were developed, and several of these …

Analysis Of The Theta-D Filter As Applied To Hit-To-Kill Interceptors And Satellite Orbit Determination, Michael W. Dancer

Masters Theses

"When designing feedback control systems, there is often a need for estimation methods that provide system information that is not readily available via sensors placed within the system. In many cases a sensor that measures a particular system state either does not exist or is prohibitively expensive. In addition, all realistic systems contain some degree of nonlinearity. This thesis focuses on two such cases: missile guidance with bearings-only measurements and GPS satellite orbit determination. In each case, a new nonlinear filter, the [theta]-D method, is used and evaluated for its performance in providing the necessary estimation. To aid the filter …

Quantification Of Channel Performance And Development And Characterization Of Small Magnetic Field Probes, Surbhi Mittal

Masters Theses

"This thesis presents a new approach to quantifying channel performance using a transmitter waveform and dispersion penalty (TWDP) with frequency domain S-parameter data. Initially TWDP was defined to characterize the performance of a transmitter in optical links. More recently its use has been extended to include the quantification of channel performance, especially in high-speed copper links. This project focused mainly on channel characterization. Instead of using the time-domain oscilloscope measurements involved in the original approach, it proposes a new method that relies on frequency-domain S-parameter data obtained either from measurements or simulations. It included a parametric study of TWDP with …

Strategic Process Integration Of Energy And Environmental Systems In Wastewater Treatment Plants, Bharath Kumar Gangichetty

Masters Theses

"Green environmental practices are increasingly important in combating serious global energy and environmental issues. Most wastewater treatment facilities were built when energy costs were not a concern; however, an increasing demand for energy, changing climatic conditions, and constrained energy supplies have resulted in the need to apply more energy-conscious choices in the maintenance or upgrade of existing wastewater treatment facilities. A detailed analysis of the majority of water and wastewater treatment services shows that most facilities operate far below the efficiency levels needed for effective energy use. Failure to comply with regulated environmental standards is also a problem. Although standards …

Strategic Criteria For Evaluating Inland Freight Hub Locations, Robert Tyler Lipscomb

Masters Theses

"The aim of this thesis is to develop criteria that can be used to evaluate the current capabilities and sustainability of inland freight hubs. A review of the literature highlights the need for a more efficient freight distribution system to combat supply chain deficiencies and the important role that inland freight hubs play in creating this system. Also in the literature is a call for a more comprehensive approach to hub development decisions and the use of multi-criteria decision analysis. The decision to devote resources to logistics developments in a specific region must consider many factors that are both quantitative …

The Placement Of Remediation Amendments Into Contaminated Sediments Via Waterjet Technologies, Gavin Hunter Ray Risley

Masters Theses

"The use of amendments to perform in situ remediation of contaminated sediments is a technique that is relatively mature. The need exists to develop a method of amendment delivery that will efficiently place the amendments into the contaminated zone at depth with minimal impacts to the benthic communities and contaminant resuspension. Waterjets have been used for hundreds of years as an excavation, cutting, and cleaning tool, but they can also be used to inject remediation amendments into contaminated sediments if setup properly. In order to test this concept, a waterjet amendment injection system and nozzle have been developed and tested. …

Advanced Dynamic Response Improvement Methods For Dc-Dc Power Electronic Converters, Lisheng Shi

Doctoral Dissertations

"Dc-dc power electronic converters supplying electric power to digital processors, data centers, and telecommunication systems are required to exhibit a fast dynamic response in response to their instantaneous electric load variations. This requirement is becoming more and more stringent as the operating voltage of such loads is continuously reducing. This voltage level reduction has reached a point where conventional control approaches can barely meet the dynamic response demanded by such loads. In order to overcome this issue, several approaches focusing on the dynamic response improvement for dc-dc converters have been proposed in the literature. Unfortunately, most of them have at …

Borate Based Bioactive Glass Scaffolds For Hard And Soft Tissue Engineering, Steven B. Jung

Doctoral Dissertations

"The main objectives of this dissertation were to evaluate bioactive borate glass scaffolds for hard and soft tissue applications and determine the potential toxicity of the borate glasses on the adjacent and systemic tissues. Porous randomly oriented fiber scaffolds composed of bioactive borate glass were implanted in subcutaneous soft tissue sites and in calvaria defects of laboratory rats and no signs of toxicity (necrotic tissue, increase in macrophages or other immune cells) were detected in any of the adjacent tissues (hard or soft). Systemic organs (kidney and liver) of laboratory rats implanted with bioactive borate scaffolds were analyzed for possible …

Identifying Multiple Steady States In The Design Of Reactive Distillation Processes, Thomas Karl Mills

Doctoral Dissertations

"Global homotopy continuation is used to identify multiple steady states in ideal reactive flash and reactive distillation systems involving a reaction of the form A+B [symbol for <--> C taking place in the liquid phase. The choice of specifications has an influence on the existence of multiple solutions for both the flash and the column. For the flash, specification of the heat input or withdrawal can give rise to multiplicities while specification of the split fraction does not. Specification of one internal energy balance variable and one external material balance variable does not produce multiplicities in the column; however, specification of …

Finite Element Analysis And Fatigue Test On The Bicuspids To Support Theory Of Abfraction, Madhuchandra Mahadevaswamy

Masters Theses

"Abfraction is a small crack or notch found at the cervical areas of a teeth due to the loss of enamel tissues in the teeth. Proposed explanations for are that it is caused by toothbrush abrasion, acid erosion, and the mechanical forces applied on the teeth due to chewing, biting, tongue activity. There is disagreement among dentists as to the primary causes of abfraction. Some dentists believe that abfraction is caused by toothbrush abrasion and erosion due to acidic food and drinks. Other dentists believe that tensile and compressive forces acting on the teeth from non-axial, cyclical loading over an …

Enhanced Photorefractivity In A Polymeric Composite Photosensitized With Modified Carbon Nanotubes, Naveen Kumar Lingam

Masters Theses

"This work involves the photosensitization of photorefractive polymeric composites through the inclusion of multiwalled and singlewalled carbon nanotubes grafted to poly(N-vinyl carbazole). The photorefractive nature of the holograms gratings was established using two-beam-coupling, yielding two-beam-coupling gain coefficients approaching 80 cm⁻¹. Degenerate-four-wave-mixing experiments exhibited diffraction efficiencies as high as 60% as well as over-modulation voltages as low as ~ 40 V/µm. These notable figures of merit indicate that the grafting of the various carbon nanotubes to the poly(N-vinyl carbazole) polymer resulted in enhanced photorefractive performance. The mechanism responsible for this enhancement in photorefractive performance is investigated using a variety of experimental …

Bayesian Approaches On Observational Before-After Highway Safety Analysis, Daxiao Liu

Masters Theses

"Observational before-after evaluation of roadway safety treatments effect is a necessary and challenging study area for traffic safety engineers. In decades, empirical Bayesian approach has been widely adopted among researchers in this area. In this approach, the researcher combined before period observation data with a safety performance function estimated from similar groups to estimate the expected number of crashes that would have occurred in the after period without the treatment. Comparing this estimate with the number of crashes observed in the after period, the researcher evaluated the effectiveness of the treatment. This approach accounts for well-known regression-to-the-mean effects. However, as …

Modeling The Practical Performance Of Switched-Capacitor Converters And A Method For Automating State-Space Model Generation, Jordan M. Henry

Masters Theses

"A new modeling technique and a method for automating the modeling process are introduced for analyzing complex switched-capacitor (SC) converters. The model uses conventional circuit analysis methods to derive state-space models of each switching state. Steady-state performance is derived and expressed as an equivalent resistance. Whereas previous techniques have provided either the detailed performance of a simple SC converter or the limiting performance of a complex SC converter, this new model is flexible enough to provide detailed performance for any practical converter. Nonuniform component choices, asymmetric duty cycles, and other deviations from an ideal converter can be readily included. Dynamics …