Digital Commons Network^™

Controlling Phase Fractions Of 304l-Ss In Selective Laser Melting Using Cooling Rate, Eberechukwu Anthony Okoro

Masters Theses

"This study examines the thermal profile and the ferrite-austenite phase fractions upon heating and cooling of 304- stainless steel powder via Selective Laser Melting (SLM). Experiments were performed to validate the ABAQUS finite element model, while the phase transformation simulation was performed using MatCalc and ThermoCalc. A correlation between the thermo-mechanical changes in ABAQUS and the microstructural changes from MatCalc was obtained by matching their cooling rates. The result indicates that cooling rate has a significant effect on the phase fractions of FCC and BCC formed in 304L stainless steel via the SLM process. The results also indicate that for …

Cyber-Physical Security Of An Electric Microgrid, Prashanth Palaniswamy

Masters Theses

"Cyber-physical systems (CPSs) are physical systems that are controlled or monitored by computer-based systems. CPSs are a combination of computation, networking, and physical processes. As CPSs are a combination of various diverse components, they are vulnerable to several security threats. Moreover, there are many different security domains (not just high/low, nor necessarily hierarchical). This paper utilizes previously developed multiple security domain nondeducibility (MSDND) to uncover potential integrity vulnerabilities in an electric microgrid. Invariants are manually generated using the insights obtained through MSDND analysis and use linear regression to automate the generation of invariants. The vulnerabilities are then mitigated, to the …

Generalized Adaptive Variable Bit Truncation Model For Approximate Stochastic Computing, Keerthana Pamidimukkala

Masters Theses

"Stochastic computing as a computing paradigm is currently undergoing revival as the advancements in technology make it applicable especially in the wake of the need for higher computing power for emerging applications. Recent research in stochastic computing exploits the benefits of approximate computing, called Approximate Stochastic Computing (ASC), which further reduces the operational overhead in implementing stochastic circuits. A mathematical model is proposed to analyze the efficiency and error involved in ASC. Using this mathematical model, a new generalized adaptive method improving on ASC is proposed in the current thesis. The proposed method has been discussed with two possible implementation …

An Approach For Formal Analysis Of The Security Of A Water Treatment Testbed, Sai Sidharth Patlolla

Masters Theses

"This thesis focuses on securing critical infrastructures such as chemical plants, manufacturing units, and power generating plants against attacks that disrupt the information flow from one component to another. Such systems are controlled by an Industrial Control System (ICS) that includes controllers communicating with each other, and with physical sensors and actuators, using a communications network.

Traditional security models partition the security universe into two worlds, secure and insecure, but in the real world the partitions often overlap and information is leaked even through the physical observation which makes it much harder to analyze a Cyber physical system (CPS). To …

Loss Of Trust: The Negative Effects Of Leader Discrimination And The Mitigating Effects Of Organizational Response, Andrew Wade Pepper

Masters Theses

"This thesis focuses on how perceptions of leader discriminatory behavior influence trust in the leader and, subsequently, attitudes about the organization which the leader represents. This study builds on previous research findings by creating a 2 (discriminatory interaction) X 2 (procedural response) X 2 (distributive response) experimental design model with vignettes that focused a leader's discriminatory or non-discriminatory behaviors and how the organization responds to accusations of such behavior. Participants (N = 293) were recruited from Amazon Mechanical Turk and randomly assigned to read one of the two vignettes describing a supervisor's discriminatory or non-discriminatory behavior. After reporting perceptions shaped …

Fuel Burnup Simulation And Analysis Of The Missouri S&T Reactor, Joshua Hinkle Rhodes

Masters Theses

"The purpose of this work is to simulate the fuel burnup of the Missouri S&T Reactor. This work was accomplished using the Monte Carlo software MCNP. The primary core configurations of MSTR were modeled and the power history was used to determine the input parameters for the burnup simulation. These simulations were run to determine the burnup for each fuel element used in the core of MSTR.

With these simulations, the new predicted isotopic compositions were added into the model. New core configurations were determined, and the burnup corrected model was used to predict the excess reactivity and control rod …

Investigation Of The Information Provided By Light Touch For Balance Improvement In Humans, Anirudh Saini

Masters Theses

"This study investigates the information provided by Light Touch (LT) in improving human postural stability without mechanical assistance. Light Touch, an interaction force with a magnitude about 1 N, is known to improve postural stability in humans during quiet standing. However, the nature of the information from LT that helped improve balance is yet unknown. In this work, we hypothesized that LT provides information about one's body kinematics. We used a haptic robot to provide modulated, measurable light interaction force on the high back haptic location of humans to provide body kinematics-dependent information through LT. Standing balance experiments were performed …

Management Of Coal Dust Explosions In United States' Coal Mines Using Bag Type Passive Explosion Barriers, Jay Robert Schafler

Masters Theses

"The most significant and powerful hazard that exists in an underground coal mine is a coal dust explosion. A coal dust explosion has the potential to propagate throughout a mine resulting in massive damage to the mine and equipment, as well as tragic loss of life. An assessment of current global regulations and practices uncovered four main control methods utilized to prevent coal dust explosions in coal mines world-wide. The United States is one of the few countries that does not regulate or employ all four of these safety practices. Additionally, a review of past research into coal dust explosions …

Cellular Hitchhiking Via Injectable Microparticles, Daniel Smith

Masters Theses

"Tissue engineering is a process of developing new tissues in a host. Tissue engineering draws upon revitalizing damaged tissues that otherwise would not heal completely from the body's natural response. To augment the body's natural response to impairment, cells can be transplanted to the afflicted area to boost the healing response. Implementing these cells onto scaffolds and transplanting them into the body improves the healing response dramatically. Tissue regeneration improves when a biodegradable scaffold is used in conjunction with cells to augment the body's healing response. Microparticles provide a surface that can mimic the environment cells perceive in vivo, …

Proppant Transport With Varying Injection Points And Its Impact On Proppant Development Inside A Fracture, Shail Janakbhai Soni

Masters Theses

"This study presents experimental work which examines the effect of perforation placement and density on proppant placement within a hydraulic fracture. The study also investigates the effect of proppant angularity.

Experiments were conducted with ceramic proppant injected in a fracture slot model consisting of three injection points at the bottom, middle and top of the fracture slot, and two outlets, at the bottom and top of the fracture model. The effect of single point injection height was investigated by injecting solely at the bottom, middle or top of the apparatus, for both bottom and top outlet conditions. Multiple injection points …

The Role Of Flexural Slip In The Development Of Chevron Folds, Yuxing Wu

Masters Theses

"Chevron folds are characterized by straight limbs and narrow hinge zones. One of the conceptual models to initiate and develop chevron folds involves flexural slip during folding. While some kinematical models show the necessity for slip to initiate during chevron folding, recent numerical modeling studies of visco-elastic effective single layer buckle folding have shown that flexural slip does not result in chevron folds. In this study, several 2D finite element analysis models are run, distinguished by 1) geometry of the initial perturbation (sinusoidal and white noise), 2) varying thewavelength of the initial perturbation (10%, 50%, and 100% of the dominant …

A Network Tomography Approach For Traffic Monitoring In Smart Cities, Ruoxi Zhang

Masters Theses

"Various urban planning and managing activities required by a Smart City are feasible because of traffic monitoring. As such, the thesis proposes a network tomography-based approach that can be applied to road networks to achieve a cost-efficient, flexible, and scalable monitor deployment. Due to the algebraic approach of network tomography, the selection of monitoring intersections can be solved through the use of matrices, with its rows representing paths between two intersections, and its columns representing links in the road network. Because the goal of the algorithm is to provide a cost-efficient, minimum error, and high coverage monitor set, this problem …

Lyapunov Stability Analysis Of Switched Microgrid Systems, Bokang Zhou

Masters Theses

"In this thesis, a Lyapunov-based method for analyzing the stability of a switched microgrid system is proposed. First, a small second-order system is explored as example to demonstrate the effectiveness of switching patterns on the stability of a system switching among different respectively stable operating points. Lyapunov function is employed in order to determine the proper state-based switching conditions under which global stability is guaranteed, or under which the system is driven unstable. Then, a linearized statespace model of a looped seven-node microgrid is established. Solid-state transformers (SSTs), distributed energy storage devices and synchronous generators are introduced and modeled in …

Embedded Fiber Optic Sensors For Temperature Monitoring Of Continuous Casting Mold, Yiyang Zhuang

Masters Theses

"The continuous casting process has been widely used for most of the steel production in the world instead of conventional ingot casting/rolling. Traditionally, thermocouples are being widely used to monitor the mold temperature in the continuous casting which has the following drawbacks: large size, low spatial resolution, and single detection point. On the contrary, fiber optic sensors can be a promising solution to the continuous casting temperature monitoring owing to its advantage of compact size, high resolution, high-temperature survivability, etc.

In this thesis, we successfully developed extrinsic Fabry-Perot interferometer (EFPI) sensor for point temperature sensing, and optical frequency domain reflectometry …

Card: Concealed And Remote Discovery Of Iot Devices In Victims' Home Networks, Sammie Lee Bush

Masters Theses

"Smart devices are becoming more common in the standard households. They range from lights to refrigerators and their functionality and applications continues to grow with consumer demand. This increase in networked, complex devices has also brought an increase in vulnerabilities in the average consumer's home. There now exists an Internet of Things (IoT) ecosystem that creates new attack vectors for adversaries to spread malware, build botnets, and participate in other malicious activities. We will overview some of these new attack vectors as well as go over a framework that would allow an adversary to target a user's home network and …

Grain Refinement Of High Alloy Stainless Steels In Sand And Directionally Solidified Castings, Dustin Alan Arvola

Masters Theses

"The goal of this research project is to develop an industrially viable melting process that will control the crystallization macrostructure of austenitic grades of cast steels. Titanium nitride (TiN) has proven to be an effective grain refiner of austenite. Theoretical simulation and experimental application has led to the development of a repeatable grain refining melt process for austenitic stainless steel alloys.

Grain refinement of the as-cast structure of Cr-Ni stainless steel alloys solidified with primary FCC, BCC and dual FCC/BCC phases was studied experimentally. Refinement was achieved in both cast ferritic and austenitic grades. Dual solidification of …

Reprocessing Of 3c-2d Seismic Reflection Data From The Spring Coulee Field, Alberta, Yasin Demir

Masters Theses

"The 3C-2D seismic datasets were acquired in 2008 in the Spring Coulee Field, Alberta, which is located in Township 4, Range 23, and west of the 4th Meridian in the Alberta Basin. Line 2008-SC-01 was reprocessed to obtain better image of the formation targeted at between 1300 ms and 1400 ms. The depositional settings of the Madison Formation consist of shallow and carbonate shelf deposits. The processing workflow was designed by testing several methods, algorithms, and parameters, and finding the optimal processing solution. The processing steps included elevation statics, noise suppression, deconvolution operator, and 2D Kirchhoff poststack time migration. In …

A Hybrid Cavity And Parallel-Plate Peec Method For Analysis Of Complex Power Net Area Fills, And A Tool Development For Peak Distortion Analysis, Chenxi Huang

Masters Theses

"Modern ASICs and FPGAs are becoming more and more dense, which is causing an increasing demand of the current draw from the power distribution network (PDN). And one of the main design objectives of a power distribution network is to reduce the voltage noise ripple below a specified allowable limit. Although the target impedance is a commonly used criterion in most PDN designs, it may not be efficient because it's usually rather pessimistic. Herein a time domain voltage ripple decomposition approach is proposed to avoid overdesign as well as provide design guidance to PI engineers. Based on a physics-based circuit …

Developing An Energy Efficient Real-Time System, Aamir Aarif Khan

Masters Theses

"Increasing number of battery operated devices creates a need for energy-efficient real-time operating system for such devices. Designing a truly energy-efficient system is a multi-staged effort; this thesis consists of three main tasks that address different aspects of energy efficiency of a real-time system (RTS).

The first chapter introduces an energy-efficient algorithm that alternates processor frequency using DVFS to schedule tasks on cores. Speed profiles is calculated for every task that gives information about how long a task would run for and at what processor speed. We pair tasks with similar speed profiles to give us a resultant merged speed …

Effects Of Terrain-Based Altimetry On Navigation Performance, Kenneth Michael Kratzer

Masters Theses

"Navigation filters used during an entry, descent, and landing scenario often receive measurements related to the terrain over which the vehicle is traversing. Models of the terrain can be presented in varying degrees of fidelity, providing increasingly realistic and accurate models of the surface. While it is ideal to provide the filter with the most realistic model possible, the performance is limited by the strict nature of the real time scenario. Therefore, it is of interest to determine what level of fidelity is necessary to achieve an accurate filtering solution. Determining how best to incorporate terrain-related data into navigation solutions …

Analyzing Sensor Based Human Activity Data Using Time Series Segmentation To Determine Sleep Duration, Yogesh Deepak Lad

Masters Theses

"Sleep is the most important thing to rest our brain and body. A lack of sleep has adverse effects on overall personal health and may lead to a variety of health disorders. According to Data from the Center for disease control and prevention in the United States of America, there is a formidable increase in the number of people suffering from sleep disorders like insomnia, sleep apnea, hypersomnia and many more. Sleep disorders can be avoided by assessing an individual's activity over a period of time to determine the sleep pattern and duration. The sleep pattern and duration can be …

Quantifying On-Orbit Performance Of Cubesat Micropropulsion Systems By Observing Orbital Element Variations, Bradyn William Morton

Masters Theses

"The Advanced Propulsion Experiment mission in development by the Missouri University of Science and Technology's satellite research team (M-SAT) is a technology demonstration mission of a multi-mode propulsion system. The true test of any satellite propulsion system is the on-orbit performance. The purpose of this research is to develop methods for quantifying the on-orbit performance of the multi-mode propulsion system. This performance can be determined by observing the small variations in the orbital element parameters and using a differential corrector with the Gauss Variation of Parameter equations. Furthermore, this research could be used to determine and quantify a propulsion system's …

Research And Development Of Optically Transparent Join With Low Processing Temperatures, Eric Kevin Muskovin

Masters Theses

The purpose of this study was to investigate durable solar cell cover glass joins produced by diffusion bonding with deep eutectic solvents (DES) and to develop a novel process of joining optically transparent materials at low temperatures. A joined PV cell-glass specimen was characterized using Raman, μ-FTIR, SEM-EDS, and thin-film XRD. DESs were created with malonic acid (MAL) and choline chloride (ChCl) of varying composition factors (CF; CF=MAL/ChCl). Joining borosilicate glass coupons was attempted using DESs with CF = 0.65 and 1 at temperatures between 100-150 °C for 20 hours. Joining the glass coupons failed at all temperatures and oxygen …

Analyzing Large Scale Trajectory Data To Identify Users With Similar Behavior, Tyler Clark Percy

Masters Theses

"In today's society, social networks are a popular way to connect with friends and family and share what's going on in your life. With the Internet connecting us all closer than ever before, it is increasingly common to use social networks to meet new friends online that share similar interests instead of only connecting with those you already know. For the problem of attempting to connect people with similar interests, this paper proposes the foundation for a Geo-social network that aims to extract the semantic meaning from users' location history and use this information to find the similarity between users. …

Modeling And Control Of Three-Phase Grid-Connected Pv Inverters In The Presence Of Grid Faults, Paresh Vinubhai Patel

Masters Theses

"A two-stage photovoltaic grid-connected microgrid modeling approach is presented in this work. The purpose of the modeling is the behavior study of the microgrid during the low-voltage event on the grid. A complete mathematical model is discussed for each component of the system. The MPPT of the photovoltaic system is integrated with the boost controller to inject the constant current in the DC-link. The boost converter and the inverter control is implemented using the cascaded PI control. A dual second-order generalized integrator (DSOGI) method is implemented for the sequence extraction. The inverter controller is designed to meet the grid-code requirement …

Impact Of Probable And Guaranteed Monetary Value On Cybersecurity Behavior Of Users, Santhosh Kumar Ravindran

Masters Theses

"This research examines the impact of probable and guaranteed monetary gains and losses on users' cybersecurity behavior. It also examines perceptual outcomes such as threat severity, trust, and fear that are associated with users' cybersecurity behavior. Drawing on Prospect Theory in the behavioral economics and decision-making literature, hypotheses were generated for the research. The hypotheses state that: (i) users are more willing to engage in risky computer security behavior to avoid a loss than to receive a gain, (ii) users exhibit a higher tipping point of expected monetary value to receive a gain than to avoid a loss for engaging …

Customized Multi-Group Cross Section Generation With Njoy For Discrete Ordinates Computed Tomography And Radiography Simulation, Steven Michael Wagstaff

Masters Theses

"The purpose of this work was to explore the creation of photoatomic multi-group cross section libraries to be used with a software package DOCTORS (Discrete Ordinates Computed TOmography and Radiography Simulator). This software solves the linear Boltzmann equation using the discrete ordinates method [1]. To create these libraries, NJOY2016 was used, creating both fine and broad energy multi-group cross section files. The cross section's accuracy was tested against an equivalent Monte Carlo simulation using MCNP6.

Two simulation geometries were used. The first, a cylindrical water phantom with a single source projection placed in front, simulating an X-ray radiography. The second …

Neural Correlates Of Flow, Boredom, And Anxiety In Gaming: An Electroencephalogram Study, Tejaswini Yelamanchili

Masters Theses

"Games are engaging and captivating from a human-computer interaction (HCI) perspective as they can facilitate a highly immersive experience. This research examines the neural correlates of flow, boredom, and anxiety during video gaming. A within-subject experimental study (N = 44) was carried out with the use of electroencephalogram (EEG) to assess the brain activity associated with three states of user experience - flow, boredom, and anxiety - in a controlled gaming environment. A video game, Tetris, was used to induce flow, boredom, and anxiety. A 64 channel EEG headset was used to track changes in activation patterns in the frontal, …

Effect Of Microstructural Features On Steel Machinability, Mark C. Emmendorfer

Masters Theses

Non-metallic inclusions can have a tremendous impact on the machinability of steel. Some oxide inclusions such as alumina, spinel, and other refractory abrasive oxide inclusions can have a detrimental effect on machinability. Modification of oxide inclusions by calcium treatment can promote the formation of low melting point oxides such as anorthite and gehlenite inclusions that can assist in chip formation and form a lubricating layer on the rake surface of the machine tool. MnS is known to be beneficial to improving the machinability of steel. They assist in chip formation by being heavily deformed in the primary shear zone. Sulfide …

The Development Of A New Formulation Of Fly Ash Class C Based Geopolymer And Assessing Its Performance In Presence Of Drilling Fluid Contamination, Mohamed Saad Ahdaya

Masters Theses

"Cementing is one of the most critical steps in the drilling and completion of oil wells. Traditionally, Portland cement is used for oil cementing operations; however, geopolymer materials have recently attracted much attention because they are more cost-effective and have less environmental impacts.

An intensive laboratory work was conducted to obtain a new formulation of fly ash class C based geopolymer cement to be used as a potential alternative cementing material to Portland cement in oil and gas cementing. Twenty-four variations of fly ash class C based geopolymers were prepared, and by comparing several of their properties using API standard …