Engineering Commons^™

Data-Driven Approaches To Solve Inverse Problems, Peijie Qiu

McKelvey School of Engineering Graduate Student Theses & Dissertations

The main purpose of this thesis is to discuss data-driven approaches to solve inverse problems in image reconstruction. In the Bayesian framework, the image prior serves as a regularizer in the computation of a maximum-a-posterior estimation of the reconstructed image. Classical image priors include Gaussian random space(e.g. Tikhonov regularization) or Besov prior (e.g. Total Variation regularization). Inspired by generative adversarial networks, a critic (discriminator) can serve as a regularizer, because of its capability of distinguishing the distribution of the ground-truth images from the distribution of the naively reconstructed images with classical regularization functional. Another data-driven approach, regularization by denoising (RED), …

Ph-Responsive Oxygen/Glucose Delivery System To Increase Cell Survival Under Ischemia, Yubin Ying

McKelvey School of Engineering Graduate Student Theses & Dissertations

Ischemic diseases, including myocardial infarction, stroke and limb ischemia, are life-threatening vascular diseases with high mortality. Under ischemic condition, less blood supply causes insufficient oxygen and nutrients transported to the affected tissues, which leads to cell death. To support cell survival under ischemia, oxygen and nutrients (especially glucose) are needed for aerobic respiration to generate energy. Therefore, directly supplying oxygen and glucose to the ischemic tissues is a promising therapy for ischemic diseases. In this work, we aim to design biomaterials to deliver oxygen and glucose to enhance cell survival under ischemia. In the first project, we fabricated oxygen releasing …

Mechanics Of Catheter Herniation, Chase Hartquist

McKelvey School of Engineering Graduate Student Theses & Dissertations

Endovascular catheter-based technologies have revolutionized the treatment of complex vascular pathology. Catheters and endovascular devices that can be maneuvered through tortuous arterial anatomy have enabled minimally invasive treatment in the peripheral arterial system. Although mechanical factors drive an interventionalist's choice of catheters and sheaths, these decisions are mostly qualitative and based on personal experience and procedural pattern recognition. The field currently lacks a definitive quantitative characterization of endovascular tools that are best suited for specific peripheral arterial beds. This approach gives rise to a phenomenon called catheter herniation, which occurs when a catheter is energetically displaced or buckles while a …

Numerical Simulation Of Flow Past An Airfoil With Ice Accretion On Leading Edge, Boyu Wang

McKelvey School of Engineering Graduate Student Theses & Dissertations

The focus of this research is on aerodynamic simulation of flow past NACA 23012 airfoil with clean surface and with ice accretion on its leading edge by using the commercial CFD solver ANSYS Fluent. Reynolds-Averaged Navier-Stokes (RANS) computations are performed using Spalart-Allmaras (SA) and Wray-Agarwal (WA) turbulence models. ANSYS mesh package ICEM is used to model the geometry and generate the mesh. The computations are performed at 0, 2, 4, 6, 8, 10, and 12 degrees angle of attack which are compared with experimental data. For the case of ice accretion at the leading edge, the physical geometry becomes more …

Computational Fluid Dynamics And Fluid Structure Interaction Research On Flow In A Glenn Shunt And A Flexible Tube And On A Cantilevered Plate, Chunhui Wang

McKelvey School of Engineering Graduate Student Theses & Dissertations

This thesis employs Computational Fluid Dynamics (CFD) simulation technology to solve three flow problems: (1) Blood flow in a Bidirectional Glenn Shunt and a combined Bidirectional Glenn Shunt (BGS) and Blalock-Taussing (BT) Shunt. This shunt is used to address the problem of Cyanosis or “Blue Baby Syndrome,” which is an infant disorder that affects the newly born babies whose skins turn blue or purple because of lack of necessary blood flow between heart and lung due to pulmonary vascular blockage. The goal of this study was to evaluate the performance of BGS and combined BGS+BT shunt in achieving the desired …

Numerical Simulation Of Gas-Solid Flow In A Fluidized Bed With Different Inlet Flow Locations, Feng Feng

McKelvey School of Engineering Graduate Student Theses & Dissertations

No abstract provided.

Magnetic Resonance-Guided High Intensity Focused Ultrasound (Mrghifu) Induced Hyperthermia (Ht) For Treatment Of Cervical Cancer, Lifei Zhu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Hyperthermia (HT), which refers to increasing the temperature of the tumor tissue to 40–45°C for an extended period of time, has been reported to be one of the most effective sensitizers for radiation therapy (RT) and/or chemotherapy. High intensity focused ultrasound (HIFU) has been developed as a non-invasive and non-ionizing tool to induce localized HT. Magnetic resonance thermometry (MR thermometry) is one of the most reliable methods for non-invasively and precisely measuring the in vivo volumetric temperature in real time. The integration of MR thermometry with HIFU has been implemented in commercially available magnetic resonance guided high intensity focused ultrasound …

Bimetallic Catalyst For Lignin Depolymerization, Qishen Lyu

McKelvey School of Engineering Graduate Student Theses & Dissertations

This thesis is motivated by concerns regarding the need to develop more sustainable and economic technologies to meet rising global manufacturing and energy demands. These concerns have renewed governmental, industrial, and societal determination to reduce the world’s dependence on conventional natural resources and has led to considerable research on producing fuels and chemicals from feedstocks other than petroleum. Lignocellulosic biomass represents an abundant and renewable resource that could displace petroleum feedstock producing biofuels and multiple valuable chemical products with reduced greenhouse gas emissions. Lignin is the second abundant biopolymer source in nature and is found almost everywhere. Since the 1950’s, …

Converting Inorganic Rust To Organic Nanostructured Conducting Polymers: Synthesis And Applications, Yifan Diao

McKelvey School of Engineering Graduate Student Theses & Dissertations

Iron rust is a type of corrosion product, coming from the chemical reaction between iron and oxygen in the presence of water that first documented ca. 800 BCE. It is a heterogeneous inorganic solid-state material composed of multiple phases and is ubiquitous throughout the universe. Rust species such as Hematite (α-Fe2O3), Akaganeite (β-FeOOH), and ferrous hydroxide (Fe(OH)2), make up the solid-state chemical family composed of iron oxides, oxyhydroxides, and hydroxides that are typically recognized as chemical waste. Conducting polymer is a type of organic plastic composed of long chains with repeating subunits that bonding with strong interactions between neighboring molecules. …

Plasmonically-Enhanced Ultrasensitive Biodetection Technologies, Zheyu Wang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Detection and quantification of biomolecules within biological fluids and tissues is of fundamental importance to biomedical research and clinical diagnostics. It is impossible to fully characterize complex, non-linear, biochemical systems without being able to accurately and quantitatively determine the component molecules. This problem is ubiquitous across all domains of biomedical research, and it is a major barrier to fully understanding health, ageing, and disease. Such bottlenecks are extremely challenging to be solved, especially for proteins and peptides, which do not have amplification schemes such as polymerase chain reaction for nucleic acids, because relevant concentrations of molecules related to diseases such …

Engineering Nucleus Pulposus Cell-Matrix Interactions With Laminin Ligands For Tissue Regeneration, Julie Elizabeth Speer

McKelvey School of Engineering Graduate Student Theses & Dissertations

Low back pain and degenerative conditions of the intervertebral disc (IVD) represent major global socioeconomic and medical burdens. The structures that comprise the IVD including the anulus fibrosis and the nucleus pulposus (NP) work together to stabilize the axial skeleton and distribute mechanical forces. However, the degenerative cascade, which is thought to begin with changes to the NP, results in alterations to the disc that can be seen across length scales including elongated cell shapes, tissue dehydration, and loss of disc height. Patients who present clinically with these changes may also experience altered biomechanics, pain upon motion, impairments to their …

Efficient And Scalable Computing For Resource-Constrained Cyber-Physical Systems: A Layered Approach, An Zou

McKelvey School of Engineering Graduate Student Theses & Dissertations

With the evolution of computing and communication technology, cyber-physical systems such as self-driving cars, unmanned aerial vehicles, and mobile cognitive robots are achieving increasing levels of multifunctionality and miniaturization, enabling them to execute versatile tasks in a resource-constrained environment. Therefore, the computing systems that power these resource-constrained cyber-physical systems (RCCPSs) have to achieve high efficiency and scalability. First of all, given a fixed amount of onboard energy, these computing systems should not only be power-efficient but also exhibit sufficiently high performance to gracefully handle complex algorithms for learning-based perception and AI-driven decision-making. Meanwhile, scalability requires that the current computing system …

Understanding The Interactions Between Acoustic Fields And Motile Microorganisms In Microfluidic Systems, Minji Kim

McKelvey School of Engineering Graduate Student Theses & Dissertations

Acoustofluidics utilizes ultrasonic standing waves in microscale fluidic channels to manipulate cells, microorganisms, and other objects sized from tens of nanometers to tens of microns. When exposed to an ultrasonic standing wave field, particles suspended in a fluid become confined to potential minima (nodes) of the acoustic field. I will present a number of related studies that involve the interactions between acoustic fields and motile microorganisms. First, I will show how an acoustic trap-and-release method enables rapid quantification of cell motility. As a demonstration, the newly developed motility assay is applied to discriminate swimming of wild-type and mutant Chlamydomonas reinhardtii …

Synthetic Gene Circuits For Self-Regulating And Temporal Delivery Of Anti-Inflammatory Biologic Drugs In Engineered Tissues, Lara Pferdehirt

McKelvey School of Engineering Graduate Student Theses & Dissertations

The recent advances in the fields of synthetic biology and genome engineering open up new possibilities for creating cell-based therapies. We combined these tools to target repair of articular cartilage, a tissue that lacks a natural ability to regenerate, in the presence of arthritic diseases. To this end, we developed cell-based therapies that harness disease pathways and the unique properties of articular cartilage for prescribed, localized, and controlled delivery of biologics, creating the next generation of cell therapies and new classes of synthetic circuits. We created tissue engineered cartilage from murine induced pluripotent stem cells that had the ability to …

Laminin-Mimetic Peptide-Functionalized Hydrogel Systems For The Phenotypic Modulation Of Cells Of The Nucleus Pulposus, Marcos Nicolas Barcellona

McKelvey School of Engineering Graduate Student Theses & Dissertations

The intervertebral disc (IVD) has been widely observed to undergo significant structural and biochemical changes with age and maturation. As degeneration progresses, changes in extracellular matrix composition and deposition, tissue cellularity, and metabolic activity have been characterized. Although the epidemiology of disc degeneration remains unclear, it is believed that the nucleus pulposus (NP) region of the IVD may be implicated in early degeneration. Specifically, cells of the nucleus pulposus have been observed to undergo a shift from their notochordal-like juvenile phenotype to a more fibroblast-like state in a manner concomitant to degenerative events. Because the disc has inherently little capacity …

Multiprincipal Element Alloy Development Via High-Throughput Experiments, Mu Li

McKelvey School of Engineering Graduate Student Theses & Dissertations

Multiprincipal element alloys (MPEAs) are a novel class of engineering materials. As opposed to conventional alloys, where one or two elements are dominant with others in minor amount to provide improvements or supplements to the properties, there is a lack of clear solvent species in MPEAs. Since the discovery in 2004, MPEAs have stimulated the exploration of the vast compositional space offered by the increased number (≥ 3) of principal elements, and the studied alloy compositions cover an exceptionally broad range of microstructures and properties. Despite the unparalleled potential of MPEAs, the considerable number of choices in number, type and …

Aerosol Vapor Synthesis Of Organic Processable Pedot Particles And Measuring Electric Conductivity Using A 3d Printed Probe Station, Yang Lu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Conducting polymers are organic semiconductors characterized by conjugated backbones (alternating single-double bonds) that enable mixed ionic-electronic conductivity. Their polymeric nature, tunable band structure and reversible redox capability have demonstrated fundamental advances in the fields ranging from electrochemical energy storage, sensing, to electro/photo catalysis and neuromorphic engineering. Conjugated backbones, the origin of all the unique physical and chemical properties associated with conducting polymers, prevent their solubility due to high lattice energy which hinders processing. Current solution utilizes a long-chain polymer (PSS) as dopants to render conducting polymer water dispersible (PEDOT:PSS). Nonetheless, PSS is highly acidic and hydrophilic limiting applicability with acid-incompatible …

Interaction Of Aqueous U(Vi) With Goethite, Montmorillonite, And Uo2(S), Anshuman Satpathy

McKelvey School of Engineering Graduate Student Theses & Dissertations

Uranium contamination in subsurface environments is a matter of great concern throughout the world. Fate and transport of uranium in the subsurface can be controlled by U(VI) adsorption and reduction onto common iron (oxy)hydroxides and clay minerals. Aqueous U(VI) can also exchange uranium atoms with solids comprised of uranium which can potentially lead to changes in the morphology of the uranium-containing solids and affect their stability. First, the performance of multiple surface complexation models (SCMs) on adsorption of U(VI) onto goethite was analyzed for a broad range of input conditions. Individual models could fit the data for which they were …

Rational Design And Optimization Of Perovskite Semiconductors, Arashdeep Thind

McKelvey School of Engineering Graduate Student Theses & Dissertations

ABSTRACT OF THE DISSERTATIONRational design and optimization of perovskite semiconductors by Arashdeep Singh Thind Doctor of Philosophy in Materials Science and Engineering Washington University in St. Louis, 2021 Professor Rohan Mishra, Chair

Lead-halide perovskites have emerged as a promising class of semiconductors for next-generation solar cells and optoelectronic devices. Since the report of the photovoltaic effect in 2009 in CH3NH3PbBr3 and CH3NH3PbI3, the power conversion efficiency of these perovskites has rapidly approached 25.2% from 3.8%. These perovskite semiconductors can be synthesized using low-cost solution-based techniques, unlike traditional semiconductors that require slow and expensive growth techniques to reduce the formation of …

Cortical Organization In Humans And Nonhuman Primates: The Evolution Of Cognitive Areas And Circuits, Chad Joseph Donahue

McKelvey School of Engineering Graduate Student Theses & Dissertations

Similarities in organization of cerebral cortex in humans and nonhuman primates offer the promise of leveraging data from invasive animal studies to better understand the complexities of the human brain, particularly those related to higher cognitive function (e.g. attention, working memory, language). Such comparisons necessitate the identification of convincing cortical homologues (areas or regions presumed to have derived from a common ancestor), requiring an accurate interspecies mapping of cortical areas and features. To this end, I describe (i) a survey of connectivity and its measures across primate species, particularly retrograde tracing and diffusion tractography, (ii) a morphometric analysis of cognitive …

Understanding A Role For Synovium In Intra-Articular Drug Clearance: A Computational And Experimental Approach, Young Guang

McKelvey School of Engineering Graduate Student Theses & Dissertations

The synovium is a membranous tissue that governs molecular transport between the intra-articular (IA) joint space and the systemic circulatory system. Drug delivery to the IA space is an attractive option to treat localized joint diseases such as osteoarthritis. However, short residence times due to rapid clearance from the joint diminishes efficacy of IA injected drugs. While many studies exist on the clearance of drugs from the IA space, these studies lack the ability to isolate and characterize trans-synovial transport.The first aim of this dissertation establishes a computational finite element (FE) model of trans-synovial transport using multiphasic mixture theory. The …

Post-Traumatic Elbow Contracture Characterization And Physical Therapy-Based Treatment Strategies In A Preclinical Model, Alex Reiter

McKelvey School of Engineering Graduate Student Theses & Dissertations

The elbow is the most commonly dislocated joint in the pediatric population and second most common in adults. As one of the most congruous joints in the body, slight changes in biomechanics due to injury can lead to drastic reductions in range of motion causing potential quality of life issues. Post-traumatic joint contracture occurs in 12% of patients following elbow dislocation or fracture, and it is characterized by a loss in ROM, joint stiffness, and pain. Preventing joint contracture and functional deficits from occurring is one of the primary goals when managing these injuries. A rat model of joint contracture …

Subject-Specific Musculoskeletal Modeling Of Hip Dysplasia Biomechanics, Ke Song

McKelvey School of Engineering Graduate Student Theses & Dissertations

Developmental dysplasia of the hip (DDH) is characterized by abnormal bony anatomy, causes pain and functional limitations, and is a prominent risk factor for premature hip osteoarthritis. Although the pathology of DDH is believed to be mechanically-induced, little is known about how DDH anatomy alters hip biomechanics during activities of daily living, partly due to the difficulties with measuring hip muscle and joint forces. Musculoskeletal models (MSMs) are useful for dynamic simulations of joint mechanics, but the reliability of MSMs for DDH research is limited by an accurate model representation of the unique hip anatomy. To address such challenges, this …

Assessment And Diagnosis Of Human Colorectal And Ovarian Cancer Using Optical Imaging And Computer-Aided Diagnosis, Yifeng Zeng

McKelvey School of Engineering Graduate Student Theses & Dissertations

Tissue optical scattering has recently emerged as an important diagnosis parameter associated with early tumor development and progression. To characterize the differences between benign and malignant colorectal tissues, we have created an automated optical scattering coefficient mapping algorithm using an optical coherence tomography (OCT) system. A novel feature called the angular spectrum index quantifies the scattering coefficient distribution. In addition to scattering, subsurface morphological changes are also associated with the development of colorectal cancer. We have observed a specific mucosa structure indicating normal human colorectal tissue, and have developed a real-time pattern recognition neural network to localize this specific structure …

A Collaborative Knowledge-Based Security Risk Assessments Solution Using Blockchains, Tara Thaer Salman

McKelvey School of Engineering Graduate Student Theses & Dissertations

Artificial intelligence and machine learning have recently gained wide adaptation in building intelligent yet simple and proactive security risk assessment solutions. Intrusion identification, malware detection, and threat intelligence are examples of security risk assessment applications that have been revolutionized with these breakthrough technologies. With the increased risk and severity of cyber-attacks and the distributed nature of modern threats and vulnerabilities, it becomes critical to pose a distributed intelligent assessment solution that evaluates security risks collaboratively. Blockchain, as a decade-old successful distributed ledger technology, has the potential to build such collaborative solutions. However, in order to be used for such solutions, …

Translating Convolutional Neural Networks Approach To The Ventral Pathway, Victoria Zhang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Do artificial neurons in CNNs learn to represent the same visual information as the biological neurons in primate brains? Previous studies have shown that the visual recognition pathway (ventral stream) in humans and monkeys increasingly represents animate objects [16]. We used a heatmap attribution technique borrowed from convolutional neural networks to generate biological feature maps identifying regions in scenes that elicit responses from neurons along the ventral stream (V1/V2, V4, and IT). Biological feature maps were then compared to activation maps produced by units in convolutional neural networks. We found that image regions containing animals elicited increasingly larger responses along …

Design And Optimization Of An Array Of Hollow Micropillar Structures For Enhanced Evaporative Cooling, Zhikai Yang

McKelvey School of Engineering Graduate Student Theses & Dissertations

With the increasing demand for higher-performance chips, the architecture of these semiconductor devices becomes more complex, leading to the need for higher-performance cooling technologies. For example, 3D stacked chips offer several advantages, including mixed functionality, reduced signal delay, and a smaller footprint. However, these devices yield higher heat densities due to the heat compounded from one stacked die to the next. While traditional single-phase cooling technologies can dissipate large heat fluxes, its performance is inversely proportional to its hydraulic diameter leading to larger required pumping powers. Two-phase cooling is a promising technique for dissipating high heat fluxes by utilizing the …

Modulation And Long-Term Release Of Cardiac Fibroblast Secretome To Enhance Cardiac Cell Survival Under Hypoxia, Jingxuan Zhai

McKelvey School of Engineering Graduate Student Theses & Dissertations

The irreversible damage to the heart caused by myocardial infarction (MI) leads to over one million deaths in the United States every year. There are several approaches to treat MI, such as angioplasty, redirected blood flow, and electrical medical devices, but they cannot promote new cardiac tissue generation, thus leading to potential high risk of re-surgeries. To overcome this limitation, stem cell therapy is regarded as a promising method. However, the implantation of stem cells has ethical and safe concern and the efficiency is limited due to low cell engraftment. Moreover, the effect of stem cell is predominantly attributed to …

Analysis Of Fluid Flow In Redox Flow Batteries, Erfan Asadipour

McKelvey School of Engineering Graduate Student Theses & Dissertations

Redox flow batteries (RFB) hold great potential for large-scale stationary energy storage. However, their low energy density compared to other energy storage systems must improve for feasibility. Electrolyte flow distribution affects current density distribution and providing a uniform current density distribution is one way to improve RFB performance. Additionally, reducing the power consumption of the electrolytes’ pump as a source of energy loss in RFB systems increases their efficiency. Investigating both subjects requires analysis of the fluid dynamics in RFB cells.

In this thesis, a novel, computationally cost-effective hydraulic-electrical analogous model (HEAM) was developed to study fluid dynamics by implementing …

Foundations For The Coupled Inflow And Structural Dynamics Of Multi-Rotor Helicopters, Ethan Genter

McKelvey School of Engineering Graduate Student Theses & Dissertations

In this work, the Peters-Seidel finite-state model is expanded to calculate the coupled inflow and rotor dynamics of tandem rotor configurations. This establishes the foundation for a more complete multi-rotor, dynamic inflow model with finite-state methods. The derivation presented in this work is for the general case of two rotors in the same plane, overlapping and separated to varying degrees. It is the purpose of this work to study the unique and interesting dynamics and characteristics of various tandem systems heretofore not studied in a dynamic system. Moreover, it is the goal of this work to investigate how these systems …