Engineering Commons^™

Inventory-Responsive Donor-Management Policy: A Tandem Queueing Network Model, Taozeng Zhu, Nicholas Teck Boon Yeo, Sarah Yini Gao, Gar Goei Loke

Research Collection Lee Kong Chian School Of Business

Problem definition: In the blood-donor-management problem, the blood bank incentivizes donors to donate, given blood inventory levels. We propose a model to optimize such incentivization schemes under the context of random demand, blood perishability, observation period between donations, and variability in donor arrivals and dropouts. Methodology/results: We propose an optimization model that simultaneously accounts for the dynamics in the blood inventory and the donor’s donation process, as a coupled queueing network. We adopt the Pipeline Queue paradigm, which leads us to a tractable convex reformulation. The coupled setting requires new methodologies to be developed upon the existing Pipeline Queue framework. …

Cu2o Heterojunction Solar Cell With Photovoltaic Properties Enhanced By A Ti Buffer Layer, Binghao Wang, Zhiqiang Chen, Feng Zhao

Center for Electron Microscopy and Nanofabrication Publications and Presentations

In this study, semiconductor oxide cuprite (Cu2O) and indium tin oxide (ITO) heterojunction solar cells with and without a 10 nm thick titanium (Ti) thin film as the buffer layer were fabricated and characterized for comparison. The Cu2O film was formed by low-cost electrodeposition, and Ti and ITO layers were deposited on a glass substrate by sputtering. The interfacial microstructures, surface topology, and electrical and photovoltaic properties of both solar cells were investigated. The test results showed that the Ti buffer layer changed the surface morphology, resistivity, and contact potential of the electrodeposited Cu2O film. With these changes, the photovoltaic …

Cost-Effective Strengthening And Automated Inspection Of One-Way Precast Reinforced Concrete Flat Slab Bridges In South Carolina, Laxman Kc

Theses and Dissertations

In South Carolina, the South Carolina Department of Transportation (SCDOT) manages 90% of the state's inventory of 9,400 bridges built in the 1950s. With more than 30% of its bridges having been under-designed and experiencing decades of service deterioration, the implications for public safety, the economy, and the transportation system are significant. To prioritize safety and address these concerns, SCDOT is in the process of conducting thorough inspections of bridges, load ratings, and exploring cost-effective and practical methods to strengthen the bridges and reduce load postings. This study is a part of the multi-year research investigation supported by the SCDOT. …

Assessment And Development Of Collaboration Framework For Less-Than-Truckload Carriers, Bhavya Padmanabhan

Theses and Dissertations

The growth of e-commerce is changing consumer expectations for delivery services. Competition is making “faster and cheaper” a nonnegotiable part of success; hence, retailers are seeking carriers that can deliver with ever-shorter lead times and at the lowest possible cost. In this environment, large carriers have a competitive advantage due to their market power. For small-to-medium-sized less-than-truckload (LTL) carriers to stay in business, they must improve their efficiency and lower cost. A potential strategy to achieve these goals is to collaborate with other carriers. In collaborating, carriers would exchange and perform certain jobs for each other to lower their transportation …

Liquid Cooling System For A High Power, Medium Frequency, And Medium Voltage Isolated Power Converter, Hooman Taghavi

Theses and Dissertations

Controlling and transforming electrical power from one form into another is the Primary function of the power electronics systems that are employed today. These systems have a wide variety of applications and are utilized in things like industrial automation, electric cars, consumer electronics, and renewable energy systems, among other things. The functioning of power electronics systems results in the production of a substantial quantity of heat, despite the fact that these systems are very dependable and efficient. This heat must be dispersed to preserve system performance and avoid component damage. By ensuring that the working temperature of the components stays …

Conceptual Design And Preliminary Safety Analysis Of A Proposed Nuclear Microreactor For Mobile Application, A. S. M. Fakhrul Islam

Theses and Dissertations

Conceptual design and preliminary safety analysis of a proposed helium-cooled Micro Nuclear reactor In ONe megawatt (MINION) thermal output is done through three-dimensional computational analysis. Compared with the conventional high temperature gas-cooled reactors (HTGR) that use tri-structural or bi-structural isotropic (TRISO or BISO) fuel particles, MINION uses traditional clad fuel pellets. This greatly simplifies the core design and allows for a substantially more compact design thanks to the fuel’s signif-icantly higher U-235 atom density. Uranium carbide (UC) enriched up to 19.75% in U-235 is used as fuel. In the power-flattened design, U-235 enrichment varies radially between 19.75% and 10.5% in …

Developing A Vision-Based Framework For Measuring And Monitoring Water Resource Systems Using Computer Vision And Deep Learning Techniques, Seyed Mohammad Hassan Erfani

Theses and Dissertations

Increased vulnerability of water systems to extreme events and climate change is among the profound challenges facing the management of water resource systems around the world. Extreme events, including droughts, floods, and natural hazards have become more frequent and intensive, particularly in coastal regions. Floods, for instance, caused tens of billions of US dollars losses and put the lives of thousands in danger, globally. To cope with the adverse consequences of floods, a wide range of structural, non-structural, and emergency measures are studied and deployed by flood management sectors. Various flood simulation, mapping, and forecast systems have been developed to …

Extending The Convolution In Graph Neural Networks To Solve Materials Science And Node Classification Problems, Steph-Yves Mike Louis

Theses and Dissertations

The usage of graph to represent one's data in machine learning has grown in popularity in both academia and the industry due to its inherent benefits. With its flexible nature and immediate translation to real life observed objects, graph representation had a considerable contribution in advancing the state-of-the-art performance of machine learning in materials.

In this dissertation proposal, we discuss how machines can learn from graph encoded data and provide excellent results through graph neural networks (GNN). Notably, we focus our adaptation of graph neural networks on three tasks: predicting crystal materials properties, nullifying the negative impact of inferior graph …

Gpu-Enabled Genetic Algorithm Optimization And Path Planning Of Robotic Arm For Minimizing Energy Consumption, Yichuan Cao

Theses and Dissertations

The robotic arm represents a complicated mechanical system and advanced engineering principles in robotics, enabling precise and efficient manipulation and interaction with objects in a variety of applications, such as manufacturing, healthcare, space exploration, and other industries. In most cases, energy consumption of robotic tools has been given little consideration due to their perceived insignificance compared to the benefits they offer. However, the increasing capacity demands of factories and the expanding use of robotic arms necessitate careful evaluation and reduction of energy consumption. In this regard, given a task configuration, adjusting the arm's movement path emerges as one of the …

A Systems Approach To Design And Plan Sustainable Antifragile Infrastructure Based On Aggregate Footprint And Satisfaction, Farboud Khatami

Theses and Dissertations

The concepts of robustness and sustainability in planning and design of water and energy infrastructures have been extensively explored in previous research, primarily focusing on system reliability, environmental considerations, and economic aspects. This study aims to broaden the understanding of these concepts by offering comprehensive frameworks that capture the essence of robustness and sustainability at two distinct levels.

The first level of investigation focuses on the performance of infrastructure networks during natural disasters. Traditionally, this has been addressed using reliability, resilience, and vulnerability metrics. However, these methods rely on static, deterministic, and non-stationary data, which is inadequate when dealing with …

Streamwise And Vertical Dispersal Of Tracer Stones From A Continuously Supplied Source, Amanda Grace Balkus

Theses and Dissertations

Individual movement of sediment grains is oftentimes studied with the use of tracer stones. Studies performed both in the field, in the laboratory and with numerical models involve installing a patch of stones (tracers) on the bed surface and rarely deep in the deposit. Once installed, particle displacement is monitored over time scales varying from one flood to several years. These studies are useful, for example, to study bedload transport dynamics, understand contaminant fate and transport as well as to identify and define stream restoration practices (e.g. quality of fish habitat). Here we use a vertically continuous model to study …

Automated Fiber Placement Through Thickness Defect Stacking Optimization, Noah Christopher Swingle

Theses and Dissertations

In its 2022 commercial market outlook, Boeing forecasted an 80% increase in the global fleet through 2041 compared to 2019 pre-pandemic levels. This sharp rise in demand will drive pressure onto airframe manufacturers to ramp up production and find more efficient ways to design and manufacture airplanes. Complicating this challenge is the industry’s recent transformation from traditional metal-based airframes towards hybrid composite-metal aircraft. While composites have been used in aviation for decades, aircraft manufacturers are still struggling to design and manufacture quality parts at a high rate. Automated Fiber Placement (AFP) is one of the main manufacturing techniques used to …

Development Of Atomistic Machine Learning Approaches For Thermal Properties Of Multi-Component Solids And Liquids, Alejandro David Rodriguez

Theses and Dissertations

Currently, heat transfer in many industries is the limiting factor for innovation, especially in the energy sector. For example, maximizing thermal conductivity of ceramic coatings in power plant devices improves the overall electrical to thermal energy ratio, whereas minimizing thermal conductivity is required for desirable heat-to-electricity conversion in thermoelectric devices. As such, rapid discovery of new materials with extreme thermal conductivity values is quintessential for the near-future deployment of current and developing energy applications.

The vibrational properties of crystalline materials are essential for their ability to conduct heat. Fundamentally, the restorative atomic forces of displaced atoms are sufficient to represent …

Implementation Of A 3d Laser Profiler System Into A Non-Contacting Method For Rnt & Stress Measurements, Caio Neto Penna

Theses and Dissertations

Continuous welded rail (CWR) is susceptible to the development of internal forces in the rail due to thermal effects that can lead to track buckling. Railroads typically deal with the internal stresses in the rail through the inspection of the rail neutral temperature (RNT) which is the temperature at which the internal force is zero. The existing methods in the industry to measure RNT are contacting, destructive, disruptive to railroad operations, and ineffective. The proposed concept is a promising non-contacting, non-disruptive and reference-free technique to measure RNT and the stress state in the rail. The method is based on the …

Jme 4110: Door Cycling Station, Briana Kagy, Alexander Clark, William Todd, Seth Flamm

Washington University / UMSL Mechanical Engineering Design Project JME 4110

The objective of this project was to design and build a door cycling station to be used for fatigue testing commercial refrigerator doors, including the door gaskets, hinges, and handles. The system must be low maintenance and reliable for at least two million cycles, and it must fit within the provided budget. The design concept includes a rodless pneumatic cylinder and a system of wear-resistant ropes, eyebolts, and pulleys.

Experimental And Computational Fluid Dynamic Study Of Water Flow And Submerged Depth Effects On A Tidal Turbine Performance, Erfan Ghamati, Hamed Kariman, Siamak Hoseinzadeh

Research outputs 2022 to 2026

This study involves an experimental and numerical analysis of the Hunter turbine, a vertical axis turbine utilized for tidal energy. A laboratory model of the Hunter turbine, featuring an aspect ratio of 1.2, was designed and tested. Numerical equations, including the Reynolds-averaged Navier–Stokes (RANS) constant, were analyzed through computational fluid dynamics (CFD) software using the k- turbulence model to forecast turbine performance and other related flow specifications, such as pressure lines, stream velocity, and pressure. This simulation was conducted on the surface of the turbine blade, and the results were obtained accordingly. The experimental data were utilized to verify the …

Jme 4110: Gearbox Design, Nichols Drabb, Steven Nelson, Brian Sniezak

Washington University / UMSL Mechanical Engineering Design Project JME 4110

This team was tasked with designing or replacing an external gearbox for an electric-motor driven train car. A suitable replacement was sought for, but none was found; so, a complex set of gears, or compound gear train was designed. This gear train allowed for a smaller electric motor to drive the large rail car at appreciable speeds.

Jme 4110: Automated Railway Decoupler, Optimized, Robert Murphy, Grace Stonner, Adam Young, Matt Stokes

Washington University / UMSL Mechanical Engineering Design Project JME 4110

Disconnecting freight cars from one another in trains that may be many thousands of feet long involves the dangerous and inefficient operation of manual decoupling. We have produced a system that enables freight cars to disconnect remotely, streamlining rail operations and boosting efficiency.

Insights On Simulating Summer Warming Of The Great Lakes: Understanding The Behavior Of A Newly Developed Coupled Lake-Atmosphere Modeling System, Miraj Kayastha, Chenfu Huang, Jiali Wang, William J. Pringle, T. C. Chakraborty, Zhao Yang, Robert D. Hetland, Yun Qian, Pengfei Xue

Michigan Tech Publications, Part 1

The Laurentian Great Lakes are the world's largest freshwater system and regulate the climate of the Great Lakes region, which has been increasingly experiencing climatic, hydrological, and ecological changes. An accurate mechanistic representation of the Great Lakes thermal structure in Regional Climate Models (RCMs) is paramount to studying the climate of this region. Currently, RCMs have primarily represented the Great Lakes through coupled one-dimensional (1D) column lake models; this approach works well for small inland lakes but is unable to resolve the realistic hydrodynamics of the Great Lakes and leads to inaccurate representations of lake surface temperature (LST) that influence …

Genetic Algorithm Theory In Simulation Programs As A Tool For Improving The Environmental Performance Of Office Buildings, Somaia Mohamed Arafa, Esraa Mohamed Elazab, Nanees Abd Elhamid Elsayyad

Mansoura Engineering Journal

Globally, a large proportion of a building's energy is consumed to achieve thermal comfort, as promoting energy efficiency and environmental sustainability of buildings is an important global goal. Therefore, the new building regulations are geared explicitly toward energy-saving projects. However, there are usually many competitive priorities, such as maximizing energy use in office buildings, leading to the complex multi-objective optimization topic. The main objective of this research was to reduce the energy consumed for cooling load in the office buildings in the city of Cairo, which is located in a hot desert climate. This was achieved by optimizing ten different …

An Empirical Investigation Of The Behavior And Cognition Of Engineering Designers While Describing Domains Of Design Problems, John Kochenberger

Theses and Dissertations

This thesis presents a protocol study that examines the behavioral and cognitive patterns in human designers when they describe a problem domain of engineering interest through constructing concept maps. Understanding various design problem domains usually comes in design projects before the start of the formal design process and is crucial for discovering the pain points of given scenarios and identifying opportunities for creating value to improve them. Thus, this activity relies on the entrepreneurial aspects of engineering design that leads to identifying the right design problem to solve. While concept maps have been used to examine various research questions in …

The Effect Of Microstructural Defects And Geometrical Features On Fatigue Behavior Of Superelastic Nitinol Wires, Parisa Shabani Nezhad

Dissertations (1934 -)

Nitinol is an alloy of nickel and titanium, which exhibits outstanding functional properties, such as shape memory and superelastic behavior. Superelastic nitinol wires exhibit recoverable strains that are significantly greater than traditional alloys. In most of its applications, nitinol is exposed to cyclic loads, which results in functional and/or structural fatigue that ultimately leads to failure. The classical fatigue theories do not appropriately address the fatigue performance of superelastic nitinol due to the complex nature of the martensitic transformation. It has been shown that the main fatigue crack initiation sites, other than surfaces, are microstructural inhomogeneities such as voids and …

Data-Driven Porosity Prediction For Directed Energy Deposition, Georgia E. Kaufman

Electrical and Computer Engineering ETDs

Stochastic flaw formation leading to poor print quality is a major obstacle to the utility of directed energy deposition (DED), a laser and metal powder-based additive manufacturing technology for construction and repair of custom metal parts. While melt pool temperature variability is known to be a major factor in flaw formation, control schemes to decrease flaw formation are limited by a lack of physics-based models that fully and accurately describe DED. In this work, a stochastic reachability analysis with a data-driven model based on thermal images of the melt pool was conducted to determine the likelihood of violating melt pool …

Progression Of Surface Flashover In Vacuum With Polymer Insulators, Kimberly M. Faris

Electrical and Computer Engineering ETDs

In pulsed power devices, an insulator is needed to isolate the transmission line from vacuum chambers. Vacuum is used as the insulator because it contains no atoms. Since it is being used as an insulator in these pulsed power insulation systems, surface flashover in vacuum is one of the most extensively studied areas since it being the greatest constraint in providing power due to dielectrics that are not able to sustain the voltage the system is operating under. These dielectrics are used in between high voltage electrodes in various pulsed power applications as electrical insulators to limit the electric current …

Co-Activation Of The Diaphragm And External Intercostal Muscles Through An Adaptive Closed-Loop Respiratory Pacing Controller, Rabeya Zinnat Adury, Ricardo Siu, Ranu Jung

Biomedical Engineering Faculty Publications and Presentations

Introduction: Respiratory pacing is a promising alternative to traditional mechanical ventilation that has been shown to significantly increase the survival and quality of life after the neural control of the respiratory system has been compromised. However, current pacing approaches to achieve adequate ventilation tend to target only the diaphragm without pacing external intercostal muscles that are also activated during normal inspiration. Furthermore, the pacing paradigms do not allow for intermittent sighing, which carries an important physiological role. We hypothesized that simultaneous activation of the diaphragm and external intercostal muscles would improve the efficiency of respiratory pacing compared to diaphragm stimulation …

Mitochondrial Transfer From Cancer-Associated Fibroblasts Increases Migration In Aggressive Breast Cancer, Kevin F. Gwolas, Sarah Libring, Emily Berestesky, Shayan Gholizadeh, Samantha C. Schwager, Andra R. Frost, Thomas R. Gaborski, Jian Zhang, Cynthia A. Reinhart-King

Biomedical Engineering Faculty Publications and Presentations

Cancer-associated fibroblasts (CAFs) have distinct roles within the tumor microenvironment, which can impact the mode and efficacy of tumor cell migration. CAFs are known to increase invasion of less-aggressive breast cancer cells through matrix remodeling and leader–follower dynamics. Here, we demonstrate that CAFs communicate with breast cancer cells through the formation of contact-dependent tunneling nanotubes (TNTs), which allow for the exchange of cargo between cell types. CAF mitochondria are an integral cargo component and are sufficient to increase the 3D migration of cancer cells. This cargo transfer results in an increase in mitochondrial ATP production in cancer cells, whereas it …

Recognizing The Potential To Reduce Ghg Emissions Through Air Transportation Electrification, Julio Roa, Joseph Oldham, Marina Lima

Mineta Transportation Institute

California is aggressively moving forward with efforts to deploy zero-emission transportation technology to fight climate change, especially the Greenhouse Gas (GHG) emissions from the high-impact transportation sector. However, to date, the investments California has made with Cap-and-Trade funding have focused on ground transportation and some marine sources and not the aircraft at the over 140 airports in the state. Through a California-focused comprehensive GHG emissions analysis, this research project seeks to determine how RAM using electric/hybrid electric aircraft can provide new high-speed transportation for high-priority passenger and cargo movement within Fresno County and connections to coastal urban centers. Using VISION, …

Extending The Service-Life Of Bridges Using Sustainable And Resilient Abutment Systems: An Experimental Approach To Electrochemical Characterization Of Lightweight Mechanically Stabilized Earth, Fariborz M. Tehrani, Kenneth L. Fishman, Farmehr M. Dehkordi

Mineta Transportation Institute

Bridges are critical components of transportation infrastructure. This research addresses the need to extend the service life of bridges by improving the safety and reliability of bridge abutments and reducing their life-cycle cost and footprints. Mechanically stabilized earth (MSE) is a known strategy to enhance the economy and performance of bridge abutments. In addition, the application of rotary-kiln-manufactured lightweight aggregate backfills improves the performance of MSE bridge abutments with a leaner structural system. Such improvements include a reduction of structural demands due to a lower density, free drainage of granular materials, a high internal friction angle, less settlement with no …

Electrical Vehicle Charging Infrastructure Design And Operations, Yu Yang, Hen-Geul Yeh

Mineta Transportation Institute

California aims to achieve five million zero-emission vehicles (ZEVs) on the road by 2030 and 250,000 electrical vehicle (EV) charging stations by 2025. To reduce barriers in this process, the research team developed a simulation-based system for EV charging infrastructure design and operations. The increasing power demand due to the growing EV market requires advanced charging infrastructures and operating strategies. This study will deliver two modules in charging station design and operations, including a vehicle charging schedule and an infrastructure planning module for the solar-powered charging station. The objectives are to increase customers’ satisfaction, reduce the power grid burden, and …

Learning Deep Time-Index Models For Time Series Forecasting, Jiale Gerald Woo, Chenghao Liu, Doyen Sahoo, Akshat Kumar, Steven Hoi

Research Collection School Of Computing and Information Systems

Deep learning has been actively applied to time series forecasting, leading to a deluge of new methods, belonging to the class of historicalvalue models. Yet, despite the attractive properties of time-index models, such as being able to model the continuous nature of underlying time series dynamics, little attention has been given to them. Indeed, while naive deep timeindex models are far more expressive than the manually predefined function representations of classical time-index models, they are inadequate for forecasting, being unable to generalize to unseen time steps due to the lack of inductive bias. In this paper, we propose DeepTime, a …