Engineering Commons^™

Passivation Of Defects In Perovskite Materials For Improved Solar Cell Efficiency And Stability, Jinsong Huang, Xiaopeng Zheng

Department of Mechanical and Materials Engineering: Faculty Publications

Semiconductor devices , and methods of forming the same , include a cathode layer , an anode layer , and an active layer disposed between the cathode layer and the anode layer , wherein the active layer includes a perovskite layer . A passivation layer is disposed directly on a surface of the active layer between the cathode layer and the active layer , the passivation layer including a layer of material that passivates both cationic and anionic defects in the surface of the active layer .

Investigation Of Python Variable Privacy, Joshua Bartholomew

Honors Theses

This study looks at the relative security of Python regarding private variables and functions used in most other programming languages. Python has only grown in popularity due to its simple syntax and developing capabilities. However, little research has been published about how secure Python code and programs compiled from Python code actually are. This research seeks to expose vulnerabilities in Python code and determine what must be done for these vulnerabilities to be exploited by hackers to abuse potentially sensitive information contained within the program.

The proposed methodology includes examining the private variable concept in other programming languages and conducting …

Du Undergraduate Showcase: Research, Scholarship, And Creative Works: Abstracts, Emma Aggeler, Elena Arroway, Daisy T. Booker, Justin Bravo, Kyle Bucholtz, Megan Burnham, Nicole Choi, Spencer Cockerell, Rosie Contino, Jackson Garske, Kaitlyn Glover, Caroline Hamilton, Haley Hartmann, Madalyne Heiken, Colin Holter, Leah Huzjak, Alyssa Jeng, Cole Jernigan, Chad Kashiwa, Adelaide Kerenick, Emily King, Abigail Langeberg, Maddie Leake, Meredith Lemons, Alec Mackay, Greer Mckinley, Ori Miller, Guy Milliman, Katherine Miromonti, Audrey Mitchell, Lauren Moak, Megan Morrell, Gelella Nebiyu, Zdenek Otruba, Toni V. Panzera, Kassidy Patarino, Sneha Patil, Alexandra Penney, Kevin Persky, Caitlin Pham, Gabriela Recinos, Mary Ringgenberg, Chase Routt, Olivia Schneider, Roman Shrestha, Arlo Simmerman, Alec Smith, Tessa Smith, Nhi-Lac Thai, Kyle Thurmann, Casey Tindall, Amelia Trembath, Maria Trubetskaya, Zachary Vangelisti, Peter Vo, Abby Walker, David Winter, Grayden Wolfe, Leah York

DU Undergraduate Research Journal Archive

Abstracts from the DU Undergraduate Showcase.

Experimental Characterization And Manufacture Of Polymer Nanocomposite Dielectric Coatings For High-Temperature Superconductor Applications, Jacob Ryan Mahon

Theses and Dissertations

Increased implementation of high-temperature superconducting (HTS) power transmission has the potential to revolutionize the efficiency of electrical grids and help unlock a fully electric transportation infrastructure. Realizing the benefits of HTS systems has been impeded by a lack of available dielectric insulation materials that can 1) withstand the extreme cryogenic operating environment of superconductors and 2) demonstrate low temperature processing that is compatible with existing superconductor manufacturing methods. Solving this problem necessitates a high-performance dielectric material with multifunctional properties specifically suited for operation in HTS systems. A polyamide and silicon dioxide (PA/SiO2) nanocomposite material with exceptional thermal stability has been …

Simulation Of Gene Regulatory Elements For Biosensing, Mallory Bates, Svetlana Harbough, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Gene regulatory studies are of significant importance in many scenarios such as mental illness. 21% of U.S adults experience mental illnesses including 1 in 4 active-duty military personnel. Mental health can be identified in the body by different biomarkers. These biomarkers potentially controlled by riboswitches, which are located in mRNA and switch “ON” or “OFF” depending on the concentration of a biomarker. In this research, a known riboswitch reengineered and its response in the presence of a biomarker investigated. We changed computationally PreQ₁, a known riboswitch that has the smallest aptamer, and then experimentally tested against biomarkers, dehydroepiandrosterone-sulfate …

Design Improvement Of Transcatheter Aortic Valves For Aortic Stenosis Patients, Samantha K. Shoun, Ali N. Azadani

DU Undergraduate Research Journal Archive

Aortic valve disease is a common condition in patients above 60 years of age and is associated with significant morbidity and mortality. Aortic valve stenosis is characterized by the narrowing of the aortic valve, which can be quite debilitating. This disease is treated with transcatheter aortic valve replacement (TAVR), which is a rapidly expanding alternative to open-heart surgical aortic valve replacement (SAVR). Although TAVR is a less invasive than SAVR, long-term durability of the transcatheter aortic valves could be the Achilles heel of the procedure. Thus, the main objective of this research was to improve the design of transcatheter aortic …

Development And Optimization Of Classification Neural Networks For Disaster-Assessment Using Unmanned Aerial Vehicle Systems, Maria Isabel Gonzalez Bocanegra

Honors College Theses

This research focuses on increasing the classification accuracy of convolutional neural networks in an autonomous network of unmanned aerial vehicles for transportation disaster management. The autonomous network of UAVs will allow first responders to optimize their rescue plans by providing relevant information on inaccessible roads. The research seeks to explore different methods to optimize the architecture of convolutional networks for the multiclass classification of disaster-damaged roads.

Ml-Based Online Traffic Classification For Sdns, Mohammed Nsaif, Gergely Kovasznai, Mohammed Abboosh, Ali Malik, Ruairí De Fréin

Articles

Traffic classification is a crucial aspect for Software-Defined Networking functionalities. This paper is a part of an on-going project aiming at optimizing power consumption in the environment of software-defined datacenter networks. We have developed a novel routing strategy that can blindly balance between the power consumption and the quality of service for the incoming traffic flows. In this paper, we demonstrate how to classify the network traffic flows so that the quality of service of each flow-class can be guaranteed efficiently. This is achieved by creating a dataset that encompasses different types of network traffic such as video, VoIP, game …

Contributions Of Vibrational Spectroscopy To Virology: A Review, Iqra Chaudhary, Naomi Jackson, Denise Denning, Luke O'Neill, Hugh Byrne

Articles

Vibrational spectroscopic techniques, both infrared absorption and Raman scattering, are high precision, label free analytical techniques which have found applications in fields as diverse as analytical chemistry, pharmacology, forensics and archeometrics and, in recent times, have attracted increasing attention for biomedical applications. As analytical techniques, they have been applied to the characterisation of viruses as early as the 1970s, and, in the context of the coronavirus disease 2019 (COVID-19) pandemic, have been explored in response to the World Health Organisation as novel methodologies to aid in the global efforts to implement and improve rapid screening of viral infection. This review …

The Heat Is On: The Collaborations, Capacities, And Management Style Required For The Establishment And Sustainability Of Community-Owned Renewable Energy District Heating Systems In Austria, Ireland, Northern Ireland, Wales, And Scotland, Gerard Doyle

Articles

International reviews of countries’ progress at tackling climate change show that Ireland is making small levels of progress on tackling issues associated with climate change. This paper will highlight the pivotal role the State performs, both at national and local level, in creating the conditions essential for the establishment of community-owned renewable energy district heating systems. In particular, the State can provide funding for these initiatives to acquire the management and technical expertise essential for their establishment and maintenance. This paper will also examine a theoretical framework, referred to as capacity analysis, to explain the capacities that need to be …

Flow And Heat Transfer In Swirl Tubes — A Review, Florian Seibold, Phillip M. Ligrani, Bernhard Weigand

PRC-Affiliated Research

The development of modern gas turbines for aircraft propulsion and power generation demands ever-increasing efficiency, which can be achieved by rising the turbine inlet temperature. Therefore, turbine components and especially the leading edge of turbine blades are exposed to particular high thermal loads with temperatures that are well above the melting point of the material. As a result, efficient cooling techniques are essential. Swirling flows in cyclone cooling systems are a promising technique for internal turbine blade leading edge cooling since they promise high heat transfer rates in combination with relatively uniform heat transfer distributions. The current paper presents a …

Motion Field Integrated Reconstruction Using Deep Learning For Mr And Pet/Mr Respiratory Motion Correction, Sihao Chen

McKelvey School of Engineering Graduate Student Theses & Dissertations

Since motion is unavoidable in clinical human imaging studies, motion correction in PET and MRI has long been of interest for the liver/lung imaging community. Respiratory motion, the most crucial source of motion in body imaging, affects thoracic organs and the upper/lower abdomen. In MRI, motion can severely blur the images and create artifacts due to incorrect sampling of k-space data in the Fourier domain. In PET imaging, the periodic respiratory motion negatively impacts the detection of small lesions and quantification of PET tracer uptake values. Typically, breath-holding is used in clinical MR scans. However, breath-holding limits spatial coverage and …

Enhancing Pet Functionalities With Novel Geometries And Multimodal Imaging Techniques, Suranjana Samanta

McKelvey School of Engineering Graduate Student Theses & Dissertations

Positron emission tomography (PET) is a highly sensitive imaging modality that can provide in vivo quantitative information of biological processes at a biochemical level. The majority of PET systems have a ring geometry where the detectors fully encircle an axial section of a patient to provide whole-body imaging capability using multiple bed positions. However, these clinical whole-body PET systems are limited in terms of both image resolution and system sensitivity. To achieve a high resolution, customized geometries which trade global utility for application specific performance (breast, small animals etc.) imaging probes may be utilized. In some cases, an application-specific PET …

Multi-Dimensional Single-Molecule Nanoscopy: Fundamental Limits And Novel Approaches, Oumeng Zhang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Single molecules (SMs) have become important tools for studying nanoscale dynamics in biological studies since they were first optically observed in 1989. Numerous techniques, termed single molecule orientation localization microscopy (SMOLM), have been developed to measure the position and orientation of SMs. Due to the challenging signal-to-background ratio (SBR) in typical SM experiments, it is critical to understand whether an imaging system is optimal for a specific target sample. However, the maximum theoretical limit of measurement performance has yet to be quantified. In Chapter 3. We first develop a mathematical framework to compute the accuracy limit in measuring the rotational …

Shape Memory Polymer Foaming With Tunable Interconnectivity Using Off-The-Shelf Foaming Components, Natalie Marie Petryk

Theses - ALL

The ability to tune pore structures of gas-blown polyurethane shape memory polymer (SMP) foams easily and safely could improve their outcomes as hemostatic dressings or tissue engineering scaffolds and overall commercialization efforts. Incorporating physical blowing agents into the polymer mix can be used to tune pore size and interconnectivity without altering foam chemistry. Enovate (HFC-254fa) is a commonly used physical blowing agent in gas-blown foams, but the Environmental Protection Agency (EPA) considers its use unacceptable because it is a hydrofluorocarbon that contributes to global warming. Here, off-the-shelf solvents accepted for use by the EPA, acetone, dimethyoxymethane (methylal), and methyl formate, …

Hybrid Double Network Cryogels Scaffold For Repair Of Local Cartilage Defect, Kaixiang Zhang

Theses - ALL

Trauma or repeated injury to the joint can result in focal cartilage defects, which significantly increase the risk of osteoarthritis. Cartilage being avascular has limited self-healing capacity. The current method for treating cartilage defects at early stages involves implantation of autologous chondrocytes with or without a scaffold through invasive surgery; however, invasive surgery can bring pain to patients and post-operative infection risks. Therefore, injectable and biodegradable biomaterials have piqued people's interest. In the current research, we designed a hybrid double network (DN) cryogel by combining multi-arm PEG acrylate and alginate as two networks and crosslinking them at -20°C. Through different …

A Model For The Sustainable Achievement Of The Optimum Return For Crops In Greenhouses, Eman Elnahas

Theses and Dissertations

This study provides a tool for accurate estimation of the irrigation water needs for various crop combinations under different environmental conditions; and employs a genetic optimization algorithm to reach optimum combinations. In the interest of sustainability, the source of energy required to drive the pumps is selected to be a renewable source, namely solar energy, which is converted to electricity employing photovoltaic (PV) modules. Having a single crop will lead to an uneconomical system because the PV installed capacity will not be exploited most of the time.

This research was conducted by establishing the required database, generating different scenarios, assessing …

Engineering Metal-Oxide Interface By Depositing Zro2 Overcoating On Ni/Al2o3 For Dry Reforming Of Methane, Baitang Jin, Shiguang Li, Yuzi Liu, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

Zirconium oxide (ZrO₂) was deposited onto Ni/Al₂O₃ catalyst as overcoating by atomic layer deposition (ALD) for dry reforming of methane (DRM). High-temperature heating during H₂-reduction could transform the ALD-prepared ZrO₂ thin film to tetragonal phase and crack the encapsulating layer on Ni sites, which constructed a beneficial Ni-ZrO_x interface. Interfacial surface oxygen vacancies on ZrO₂ overcoating were induced by the partial reduction of ZrO₂ surface during high-temperature H₂ reduction, with the assistance of Ni. During DRM, the interfacial oxygen vacancies enhanced CO₂ activation by dissociating CO_{2 …}

Splicecube Architecture: An Extensible Wi-Fi Monitoring Architecture For Smart-Home Networks, Namya Malik

Dartmouth College Master’s Theses

The vision of smart homes is rapidly becoming a reality, as the Internet of Things and other smart devices are deployed widely. Although smart devices offer convenience, they also create a significant management problem for home residents. With a large number and variety of devices in the home, residents may find it difficult to monitor, or even locate, devices. A central controller that brings all the home’s smart devices under secure management and a unified interface would help homeowners and residents track and manage their devices.

We envision a solution called the SPLICEcube whose goal is to detect smart devices, …

Particle Formation And Thermal Radiation In Laminar Diffusion Flames With Applications To Energy And Materials, Phillip Irace

McKelvey School of Engineering Graduate Student Theses & Dissertations

Fossil fuels supply over 80% of the world’s primary energy, and if current policy and technology trends continue, global energy and energy-related carbon dioxide (CO2) emissions are predicted to increase for at least several decades owing to population and economic growth, leading to serious concerns regarding global warming. Natural gas releases less CO2 than other fossil fuels (e.g., coal and oil) and can help meet future CO2 emission targets. Natural gas combustion, however, has poor radiation heat transfer when compared to other fossil fuels owing to its low propensity for soot formation, making it difficult to use as a drop-in …

Understanding And Hardening Blockchain Network Security Against Denial Of Service Attacks, Kai Li

Dissertations - ALL

This thesis aims to examine the security of a blockchain's communication network. A blockchain relies on a communication network to deliver transactions. Understanding and hardening the security of the communication network against Denial-of-Service (DoS) attacks are thus critical to the well-being of blockchain participants. Existing research has examined blockchain system security in various system components, including mining incentives, consensus protocols, and applications such as smart contracts. However, the security of a blockchain's communication network remains understudied.

In practice, a blockchain's communication network typically consists of three services: RPC service, P2P network, and mempool. This thesis examines each service's designs and …

Learning-Based Decision Making In Wireless Communications, Chen Zhong

Dissertations - ALL

Fueled by emerging applications and exponential increase in data traffic, wireless networks have recently grown significantly and become more complex. In such large-scale complex wireless networks, it is challenging and, oftentimes, infeasible for conventional optimization methods to quickly solve critical decision-making problems. With this motivation, in this thesis, machine learning methods are developed and utilized for obtaining optimal/near-optimal solutions for timely decision making in wireless networks.

Content caching at the edge nodes is a promising technique to reduce the data traffic in next-generation wireless networks. In this context, we in the first part of the thesis study content caching at …

Atomistic Investigation Of Nucleosomal H3 Histone Tail In Unmodified And Epigenetically Modified States, Kathryn Piston

Dissertations - ALL

Epigenetics is a growing area of research that could potentially unlock the understanding of questions like how and why we develop certain diseases, how we age, how we inherit certain traits and even how our species evolves. Epi is a prefix meaning above, referring to chemical tags that sit above your genetics and dictate gene expression. Although there are many known links between certain epigenetic tags and diseases like cancer, the molecular mechanisms behind these links remains elusive. Gaining a novel understanding of the behavior of key biological targets for cancer like the histone H3 tail motivated this work. Histone …

Enhancing Grid Reliability With Phasor Measurement Units, Rui Ma

Dissertations - ALL

Over the last decades, great efforts and investments have been made to increase the integration level of renewable energy resources in power grids. The New York State has set the goal to achieve 70% renewable generations by 2030, and realize carbon neutrality by 2040 eventually. However, the increased level of uncertainty brought about by renewables makes it more challenging to maintain stable and robust power grid operation. In addition to renewable energy resources, the ever-increasing number of electric vehicles and active loads have further increased the uncertainties in power systems. All these factors challenge the way the power grids are …

Mutual Coupling Reduction Techniques For Multi-Band Base Station Antennas, Evan Christopher Wayton

Dissertations - ALL

This dissertation proposes antenna design techniques which suppress mutual coupling in densely populated dual-polarized broadband multi-band base station antenna (BSA) arrays for improved radiation characteristics. Array face densification without the proposed techniques leads to undesirable interactions between arrays and radome cover. This research is supported by extensive full-wave electromagnetic simulations, characteristic mode analysis, equivalent circuit models, and array theory. The results are validated through measurements of the radiation patterns and scattering parameters of fabricated prototypes.Upon excitation of a mid-band (MB) array, an electrically long low-band (LB) parasitic, necessary for broadband matching of the baseline LB dipole, exhibits dipole-like induced currents …

Intelligent Work Zone Using Automatic Queue Detection Systems, Li Zhao, Laurence Rilett, Ernest Tufuor

Nebraska Department of Transportation: Research Reports

This report documents the the evaluation of the effectiveness of the Advanced Queue Detection (AQD) systems installed on Interstate work zones in Nebraska. Specifically, (1) the system performance was verified by examining whether the messages displayed on the portable dynamic message signs (PDMS) were consistent with the underlying AQD logic; (2) the system efficacy was measured by determining whether driver speeds were reduced when warning messages were provided on the PDMS; and (3) the system safety impact was modeled using statistical models. It was found that overall, the AQD systems had an error rate of 0.7% – 2.3%. Drivers reduced …

Optimization And Information Problems In Operations, Puping Jiang

Olin Business School Graduate Student Theses and Dissertations

The main purpose of this dissertation is to study the optimization problems and the value of information in various commercial settings, especially in the emerging platform economy.

Chapter 1, “Data-Driven Asset Selling”. Motivated by online asset selling marketplace business (e.g., used cars and real estate), we formulate a data-driven asset selling dynamic pricing framework which utilizes platforms’ access to customers’ online behavioral data. With mild assumptions on the demand model, careful characterization of the problem structure shows that the model admits some ideal properties that facilitate our regret analysis under our dynamic programming setting. Instead of studying the policy performance …

Application Of Bismuth Oxychloride As A Colorimetric Uv Sensor Material, Kyle James Troche

Nanoscience and Microsystems ETDs

Sunlight contains about 9% UV radiation with roughly one-third of it penetrating the atmosphere and reaching the Earth’s surface. UV radiation from the sun is classified into three different types: UVA (315- 499 nm), UVB (280- 314nm), and UVC (100- 279 nm). Prolonged exposure to artificial UV radiation or direct sunlight can still induce many adverse effects such as sunburn, weakening of the immune system, and skin cancer. A wide variety of photoresistor, photodiode and colorimetric UV sensors are currently being researched to help monitor UV radiation. Our research is focused on developing a colorimetric UV sensor that is inherently …

Controlling The Emission Of Volatile Platinum Oxides To The Vapor Phase In Diesel Oxidation Catalysts, Arnab Ghosh

Nanoscience and Microsystems ETDs

Pt-based catalysts are used for the treatment of emissions from vehicles, particularly in Diesel oxidation catalysts (DOCs). Three-way catalysts are treated at temperatures ranging from 950℃-1050℃ while DOCs are aged at 800℃ for 50 hrs. At 800°C, Pt reacts with O₂ to form PtO₂ which has a high vapor pressure and can be transported through the vapor phase. These accelerated aging conditions lead to the formation of large Pt particles causing a loss of catalytic activity. In this thesis, we used model thin-film catalysts that made it possible to quantify the emission of Pt to the vapor phase …

Artificial Intelligence, Controls, And Sensor Fusion For Optimization And Modeling Of Space Missions And Particle Accelerators, Reza Pirayeshshirazinezhad

Mechanical Engineering ETDs

This PhD dissertation is devoted to developing artificial intelligence (AI) applications for space missions and particle accelerators considering constraints on the computational resources. The space mission studied in this research, the Virtual Telescope for X-ray Observations (VTXO), is the mission exploiting 2 6U-CubeSats operating in a precision formation. The goal of the VTXO project is to develop a space-based, X-ray imaging telescope with high angular resolution precision. VTXO space mission is designed and the mission is optimized to increase the performance of the mission. Trajectory optimization with AI, hybrid control, control algorithms, and high performance computing are all used to …