Engineering Commons^™

Modeling Of Quad-Station Module Cluster Tools Using Petri Nets, Aung Nay

Theses

The semiconductor industry is highly competitive, and with the recent chip shortage, the throughput of wafers has become more important than ever. One of the tools that the industry has deployed is to use of quad-station modules instead of the traditional single-station modules that allow for higher throughput and better wafer consistency by processing multiple wafers at the same time and distributing work. The industry trend is to use multiple transfer chamber robots to stack the quad-station modules in a series, particularly for etch products. In this work, the quad-station cluster tool wafer movement is modeled by using Petri net …

Developing An Accurate Simulation Model For Predicting Friction Stir Welding Processes In 2219 Aluminum Alloy, Kennen Brooks

Theses and Dissertations

Modeling of friction stir welding (FSW) is challenging, as there are large gradients in both strain rate and temperature that must be accounted for in the constitutive law of the material being joined. Constitutive laws are most often calibrated using flow stresses from hot compression or hot torsion testing, where strain rates are much lower than those of the FSW process. As such, the current work employed a recently developed method to measure flow stresses in AA 2219-T67 at the high strain rates typical of FSW. These data were used in the development of a finite element simulation of FSW …

Assessment Of Simulated And Real-World Autonomy Performance With Small-Scale Unmanned Ground Vehicles, William Peyton Johnson

Theses and Dissertations

Off-road autonomy is a challenging topic that requires robust systems to both understand and navigate complex environments. While on-road autonomy has seen a major expansion in recent years in the consumer space, off-road systems are mostly relegated to niche applications. However, these applications can provide safety and navigation to dangerous areas that are the most suited for autonomy tasks. Traversability analysis is at the core of many of the algorithms employed in these topics. In this thesis, a Clearpath Robotics Jackal vehicle is equipped with a 3D Ouster laser scanner to define and traverse off-road environments. The Mississippi State University …

Analyzing The Supply Chain Operation Of A Fast-Food Restaurant Using Simulation Modeling And Developing A Cost Estimation Optimization Model In The Disruption Period, Amit Kumar Saha

Open Access Theses & Dissertations

Supply chain operation performance is a much-discussed topic over the last decade which will lead to optimizing the resources required to provide the necessary level of customer service to a specific segment and improve customer service through increased product availability and reduced order cycle time. During disruption in supply chain, performance parameter changes, and the overall supply chain cost at each stage increases. External factors such as labor shortages, delayed and costly supplies, and decreased demand also contribute to this cost. This thesis work presents a research-focused analysis of a small pizza shop, under circumstances that include the loss of …

Simulating Emergency Evacuation Response In An Auditorium Space, Anna Lee

Industrial Engineering Undergraduate Honors Theses

The successful execution of emergency evacuations is very important for the protection of the public. Some emergency events, such as fires, can occur with very little warning and turn into a dangerous situation in less than a minute. With high population densities, universities have increased risk involved with evacuations. One specific area that presents high risk is auditorium spaces such as lecture halls with high densities combined with added barriers such as tables and chairs. The ability to assess a building’s emergency preparedness is necessary for keeping the public safe. Simulation is a way to conduct a theoretical event and …

Supporting Us Army Next-Generation Ground Vehicle Simulation Modeling Using An Integrated Ontology Suite, Edward Louis

All Theses

The development of the US Army’s next-generation of ground vehicle systems is supported by simulations that predict vehicle performance and inform engineering design choices in the design and acquisition process. In this paper, we describe the development of an Integrated Ontology Suite to support modeling and simulation of next generation military ground vehicles. The ontology suite is intended to address model reuse challenges and increase the shared understanding of ground vehicle system simulations. It is intended to function in a Model Library structure that stores, documents, assembles, and executes vehicle simulations. The ontology suite consists of four domain ontologies: Vehicle …

Essays On Perioperative Services Problems In Healthcare, Amogh S. Bhosekar

All Dissertations

One of the critical challenges in healthcare operations management is to efficiently utilize the expensive resources needed while maintaining the quality of care provided. Simulation and optimization methods can be effectively used to provide better healthcare services. This can be achieved by developing models to minimize patient waiting times, minimize healthcare supply chain and logistics costs, and maximize access. In this proposal, we study some of the important problems in healthcare operations management. More specifically, we focus on perioperative services and study scheduling of operating rooms (ORs) and management of necessary resources such as staff, equipment, and surgical instruments. We …

Numerical Investigation Of Heat Generation And Accumulation Contributing To Elevated Temperature In Msw Landfills, Alborz Fathinezhad

LSU Doctoral Dissertations

Landfills are complex geostructures which contains organic and inorganic municipal, and in some cases industrial, wastes and are expected to remain operational for long times. Due to the complex nature of physical, chemical, biological, and thermal reactions that carry on within the depths of a landfill, unexpected incidents such as elevated temperatures could become inevitable. While uncommon to happen, elevated temperatures cause health and environmental issues such as odors, rapid settlements, slope instabilities. In addition, elevated temperatures can negatively impact engineered components in composite bottom liners, cover systems, leachate collection, and gas extraction and recovery systems.

Air intrusion into municipal …

Simulation Of A Rapid Compression Machine For Evaluation Of Ignition Chemistry And Soot Formation Using Gasoline/Ethanol Blends, Musharrat Chowdhury

Master's Theses (2009 -)

With the projected decline of demand for gasoline in light duty engines and the advent of ethanol as a green fuel, the use of gasoline-ethanol blend fuels in heavy duty applications are being investigated where the primary mode of combustion is mixing controlled combustion. In mixing controlled combustion, a wide range of mixture conditions (equivalence ratio) exist inside the engine cylinder. The sooting tendencies of light fuels at richer conditions are not well understood. The goal of this research is to model the particulate matter emissions for gasoline/ethanol fuel blends, especially at fuel rich conditions. The computational models can then …

Closed Form Implicitly Integrated Models For Computationally Efficient Simulation Of Power Electronics, Andrew Wunderlich

Theses and Dissertations

This work describes novel closed-form, implicitly integrated (CF-implicit) models of switched-mode power converters which feature implicit integration but require no iterative numerical solving algorithm for evaluation because they are explicitly solved prior to model execution. The derived models capture the large-signal dynamic behavior of the power converters, so their use and accuracy are not limited to any one set of operating conditions. These models can be implemented in any computational environment, including directly on an existing embedded controller as a digital twin. Since no iterative solver is required, the models are highly computationally efficient and have a very predictable worst-case …

Computation Of Risk Measures In Finance And Parallel Real-Time Scheduling, Yajuan Li

Dissertations

Many application areas employ various risk measures, such as a quantile, to assess risks. For example, in finance, risk managers employ a quantile to help determine appropriate levels of capital needed to be able to absorb (with high probability) large unexpected losses in credit portfolios comprising loans, bonds, and other financial instruments subject to default. This dissertation discusses the computation of risk measures in finance and parallel real-time scheduling.

Firstly, two estimation approaches are compared for one risk measure, a quantile, via randomized quasi-Monte Carlo (RQMC) in an asymptotic setting where the number of randomizations for RQMC grows large, but …

Modelling And Simulation Of Nonstationary Non-Gaussian Wind Speed And Wind Pressure Coefficients, Minyu Xiao

Electronic Thesis and Dissertation Repository

The time series of the wind speed from hurricane and downburst events can exhibit nonstationary non-Gaussian characteristics. Moreover, the time series of the wind pressure for a stationary wind may not be Gaussian. This thesis is focused on analyzing, characterizing, and simulating nonstationary/stationary Gaussian/non-Gaussian of wind speed and wind pressure coefficients by using time-frequency transform techniques such as the S-transform (ST) and discrete orthonormal S-transform (DOST). It is shown that by removing the mean of downburst winds, the multivariate nonstationary downburst wind speed processes can be efficiently decomposed and simulated by applying ST and DOST. It was also found that …

Modeling Pattern Formation And Morphology Development In Polymer Networks, Yao Xiong

All Dissertations

Topography and morphology have considerable impacts on the functionalities of soft materials in an entire range of applications from smart optics to tissue engineering. Adapting theoretical and computational approaches, we focus on the dynamics of pattern formation and morphology development in polymer networks. This dissertation starts with studying the dynamical control of pattern formation in confined thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) gel films. The patterns are formed due to mechanical instabilities. We perform a linear stability analysis and identify the limits of this analysis in predicting pattern formation in gels. We then study the restructuring between patterns and hysteresis phenomena …

Simulation And Localization Of Autonomous Underwater Vehicles Leveraging Lie Group Structure, Easton Robert Potokar

Theses and Dissertations

Autonomous underwater vehicles (AUVs) have the potential to dramatically improve safety, quality of life and general scientific knowledge. Our coasts, lakes and rivers are filled with various forms of marine infrastructure including dams, bridges, ship hulls, communication lines, and oil rigs. Each of these structures requires regular inspection, and current methods utilize divers, which is dangerous, expensive, and time consuming. AUVs have the potential to alleviate these difficulties and enable more regular inspection of these structures. Furthermore, there are significant scientific discoveries in the fields of geology, marine biology and medicine that AUV exploration of our oceans will enable. Since …

An Improved Polynomial Chaos Expansion Based Response Surface Method And Its Applications On Frame And Spring Engineering Based Structures, Mhd A. Hafez

ETD Archive

In engineering fields, computational models provide a tool that can simulate a real world response and enhance our understanding of physical phenomenas. However, such models are often computationally expensive with multiple sources of uncertainty related to the model’s input/assumptions. For example, the literature indicates that ligament’s material properties and its insertion site locations have a significant effect on the performance of knee joint models, which makes addressing uncertainty related to them a crucial step to make the computational model more representative of reality. However, previous sensitivity studies were limited due to the computational expense of the models. The high computational …

Eagle Medical Tray Denesting & Debris Removal Process, Nicholas Allen Ungefug, Noah Chavez, Susana Shu-Lin Okhuysen, Michael Augustine Pennington

Industrial and Manufacturing Engineering

Eagle Medical Incorporated is a contract medical device packaging and sterilization company. The company purchases thermoformed medical packaging trays, which maintain the sterility of medical devices, from various manufacturers. To ensure packaging quality and to prevent cleanroom contamination, Eagle Medical inspects and sterilizes each blister tray that they order. This process is an essential non-value-added activity that creates a bottleneck. Cleanroom employees must stop packaging medical devices and attend to the processing of blister trays and packaging solutions. The blister trays arrive at Eagle’s facility in nested stacks. Vibration and movement during shipping further compresses the stacks, which makes separation …

Designing The Electrode Geometry And Electrolyte To Enhance The Product Selectivity And Activity In Carbon Dioxide Electroreduction, Samaneh Sharifi Golru

Dissertations, Theses, and Capstone Projects

Excessive utilization of the fossil fuels due to the rapid growth of the global population has resulted in a dramatic increase in the carbon dioxide (CO₂) level in the atmosphere which is the main reason for global warming and climate change. Therefore, green technologies are in high demand to develop carbon-neutral energy cycles. In this regard, CO₂ electroreduction (CO2ER) has been proposed as a promising approach for CO₂ utilization. CO2ER can mitigate the CO₂ level in the atmosphere as well as produce value-added chemicals and fuels at ambient conditions. Despite the benefits of CO_{2 …}

Therapeutic Mechanical Horse, Cade M. Liberty, Aleya Dolorfino, Peter Philips, Zuzanna Dominik, Luke Watts

Mechanical Engineering

Jack's Helping Hand and its hippotherapy participants required a device to serve as an alternative to a live horseback riding experience that could also increase the range of riders. This would provide more clients with equine-assisted therapy that has proven to better the lives of people with both physical and mental disabilities. Horses can be unpredictable, tall, and sometimes anxiety-inducing, especially for new riders. Our group’s aim was to develop a mechanical horse that will be able to reduce these issues for equine therapy centers and the riders they help. When a rider gets to practice sitting on the horse …

Simulating Electric Vehicle Short-Notice Wildfire Evacuation In California Rural Communities, Gudrun Derickson

Master's Theses

The transportation sector in California has begun a shift toward adopting Electric Vehicles (EVs) as a primary source of individual and corporate mobility. The US Government and the State of California are initiating public-sector financed charging station infrastructure to help in this change-over to EVs. Automobile companies and private enterprises are also heavily investing in Battery Electric Vehicle (BEV) infrastructure going forward. The state of California is subject to natural disasters such as Fire, Earthquakes, and periodic flooding. Increasing numbers of BEVs may add new challenges to mass evacuations that are often associated with natural disasters. This work focuses on …

Optimizing Speed Profiles For Sustainable Train Operation With Wayside Energy Storage Systems, Leon A. Allen

Dissertations

Large hauling capability and low rolling resistance has put rail transit at the forefront of mass transportation mode sustainability in terms of congestion mitigation and energy conservation. As such, rail vehicles are one of the least energy-intensive modes of transportation and least environmentally polluting. Despite, these positives, improper driving habits and wastage of the braking energy through dissipation in braking resistors result in unnecessary consumption, extra costs to the operator and increased atmospheric greenhouse gas emissions.

This study presents an intelligent method for the optimization of the number and locations of wayside energy storage system (WESS) units that maximize the …

Tokamak 3d Heat Load Investigations Using An Integrated Simulation Framework, Thomas Looby

Doctoral Dissertations

Reactor class nuclear fusion tokamaks will be inherently complex. Thousands of interconnected systems that span orders of magnitude in physical scale must operate cohesively for the machine to function. Because these reactor class tokamaks are all in an early design stage, it is difficult to quantify exactly how each subsystem will act within the context of the greater systems. Therefore, to predict the engineering parameters necessary to design the machine, simulation frameworks that can model individual systems as well as the interfaced systems are necessary. This dissertation outlines a novel framework developed to couple otherwise disparate computational domains together into …

Nuclear Thermal Rocket Engine Control Autonomy Via Embedded Decision, David Sikorski

Doctoral Dissertations

This doctoral dissertation presents an investigation of embedded decision capabilities as a means for developing nuclear reactor autonomous control. Nuclear thermal propulsion (NTP) is identified as a high priority technology for development, and is the focus of this research. First, a background investigation is presented on the state of the art in nuclear thermal rocket (NTR) engine control and modeling practices, resulting in the development of a low order NTR engine dynamic model based on the literature. The engine model was used to perform the following investigation, and is intended to serve as a research platform for the future development …

Modeling Damage Spread, Assessment, And Recovery Of Critical Systems, Justin Burns

Graduate Theses and Dissertations

Critical infrastructure systems have recently become more vulnerable to attacks on their data systems through internet connectivity. If an attacker is successful in breaching a system’s defenses, it is imperative that operations are restored to the system as quickly as possible. This thesis focuses on damage assessment and recovery following an attack. A literature review is first conducted on work done in both database protection and critical infrastructure protection, then the thesis defines how damage affects the relationships between data and software. Then, the thesis proposes a model using a graph construction to show the cascading affects within a system …

A Versatile Python Package For Simulating Dna Nanostructures With Oxdna, Kira Threlfall

Computer Science and Computer Engineering Undergraduate Honors Theses

The ability to synthesize custom DNA molecules has led to the feasibility of DNA nanotechnology. Synthesis is time-consuming and expensive, so simulations of proposed DNA designs are necessary. Open-source simulators, such as oxDNA, are available but often difficult to configure and interface with. Packages such as oxdna-tile-binding pro- vide an interface for oxDNA which allows for the ability to create scripts that automate the configuration process. This project works to improve the scripts in oxdna-tile-binding to improve integration with job scheduling systems commonly used in high-performance computing environments, improve ease-of-use and consistency within the scripts compos- ing oxdna-tile-binding, and move …

Defining Interactions Between Deformable Dna Origami And Lipid Bilayers Through Molecular Dynamics Simulation, Zachary A. Loyd

Chancellor’s Honors Program Projects

No abstract provided.

Medical Sound Simuvest, Luke Stanley, Daniel Woods, Megan Hines, Chris Cochran

Chancellor’s Honors Program Projects

No abstract provided.

Medical Sound Simu-Vest, Daniel P. Woods, Luke M. Stanley, Megan Hines, Chris Cochran

Chancellor’s Honors Program Projects

No abstract provided.

Resource Allocation For Heterogeneous Wireless Networks Of Devices With Multi-Connectivity, Monika Prakash

Dissertations

This dissertation contributes to designing an effective resource allocation scheme for multi-connectivity (MC) networks. MC is a feature that allows devices to utilize the radio resources from more than one base station simultaneously. With MC anticipated to play a key role in satisfying the stringent QoS requirements of the next-generation networks (5G/6G), it is crucial to efficiently allocate the resources across multiple connections of one or more radio access technologies (RATs).
Currently, there is a huge demand on the availability of radio spectrum resources with a large volume of different types of data traffic (Internet-of-things, human-based, machine-machine) traversing the internet. …

Characterizing Mechanical Regulation Of Bone Metastatic Breast Cancer Cells, Boyuan Liu

Doctoral Dissertations

Breast cancer most frequently metastasizes to the skeleton. Bone metastatic cancer is incurable and induces wide-spread bone osteolysis, resulting in significant patient morbidity and mortality. Mechanical stimuli in the skeleton are an important microenvironmental parameter that modulates tumor formation, osteolysis, and tumor cell-bone cell signaling, but which mechanical signals are the most beneficial and the corresponding molecular mechanisms are unknown. This work focused on bone matrix deformation and interstitial fluid flow based on their well-known roles in bone remodeling and in primary breast cancer. The goal of our research was to establish a platform that could define the relationship between …

A Decision Support Simulation To Analyze Scheduling Alternatives For Applicant Processing At Military Entrance Processing Stations (Meps), Jonathan M. Escamilla

Theses and Dissertations

Applicant processing at Military Entrance Processing Stations (MEPS) is conducted via a batch arrival process by which all applicants arrive at the beginning of the processing day. Pursuit of alternate processing scenarios has never progressed beyond the pilot stage, possibly because the Command lacks a general decision support model to evaluate the impacts of proposed policies on applicant processing operations. This research creates a discrete event simulation of MEPS applicant processing operations and applies the model to three alternative applicant processing scenarios: split-shift, appointment- based, and express-lane. Results are examined and compared to benchmarks using multiple performance measurements.