Engineering Commons^™

Development Of Iii-V And Iv Epitaxy On Sapphire Technology, Emmanuel Wangila

Graduate Theses and Dissertations

This research presents comprehensive insights into the epitaxial growth of germanium (Ge) on c-plane sapphire substrates using molecular beam epitaxy (MBE). The direct growth of Ge on sapphire typically yields three-dimensional (3D) Ge islands with diverse growth directions, multiple primary domains, and twinned crystals. However, incorporating a thin AlAs nucleation layer proves instrumental in enhancing surface and material quality. With a 10 nm AlAs layer, the achieved surface exhibits improved characteristics, including a smoother surface, single epitaxial orientation, sharper rocking curve, and a single domain. This study surpasses previous works by achieving a single primary domain and reducing twinning. Furthermore, …

Optimization Of And Mechanistic Insights Into Photocatalytic And Non-Thermal Plasma Degradation Of Organic Pollutants For Sustainable Wastewater Treatment, Yiting Xiao

Graduate Theses and Dissertations

Water pollution by organic pollutants poses a significant environmental threat, necessitating the development of advanced treatment technologies to ensure sustainable and efficient remediation. This dissertation explored innovative approaches to enhance the degradation of organic pollutants through the integration of photocatalytic and plasma-assisted systems, with a focus on optimizing these processes using methodologies ranging from response surface methodology (RSM) to advanced machine learning techniques. The first part of the dissertation investigated the degradation of organic pollutants in flocculated liquid digestate using photocatalytic titanate nanofibers (TNFs) synthesized via a hydrothermal method. This study represents the first application of TNFs, with a bandgap …

Esd-Robust 4h-Sic Low-Voltage Cmos Technology Development For High Temperature, Hui Wang

Graduate Theses and Dissertations

This dissertation explores the development and optimization of electrostatic discharge (ESD)-robust, low-voltage CMOS technology using 4H-silicon carbide (SiC) tailored for high-temperature applications, addressing the critical need for reliable semiconductor devices in harsh environmental conditions. The advent of SiC as a semiconductor material offers significant advantages over traditional silicon (Si) in harsh environments, including higher thermal conductivity, greater electron mobility, and improved electrical characteristics at elevated temperatures. This research explores the integration of 4H-SiC into CMOS technology to enhance device reliability and performance in extreme conditions such as those found in aerospace, automotive, and energy sectors. The study begins with a …

Ω-Shaped Rogowski Coil Current Sensor Optimization Design In Power Electronics Applications, Xia Du

Graduate Theses and Dissertations

Accurate switching current measurement plays a pivotal role in characterization of power devices, overcurrent protection, and real-time control of system-level operations in power electronics applications. However, the ongoing revolution in power electronics, driven by the emergence of wide bandgap power devices operating at megahertz (MHz) switching frequencies, introduces challenges for current sensor design. The urgent issue now is the need to increase current sensor bandwidth significantly to adeptly capture the rapid switching speed current. Additionally, the trend towards high power density and compact power converters in various applications demands current sensors that are not only compact and nonintrusive but can …

Patterning Synthesis Of Lead Halide Perovskites Toward Photonic Application, S. M. Nayeem Arefin

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Lead halide perovskites (LHPs) are a fascinating class of photonic materials with the potential to revolutionize various optoelectronic applications. Their diverse crystal structures, ranging from 0D to 3D configurations, offer a unique combination of properties, including high tunability and ease of synthesis. However, their inherent instability and the difficulty of patterning them into sophisticated photonic structures using conventional methods present a significant hurdle to their widespread applications. This thesis addresses these challenges by proposing a novel synthesis method that combines soft lithography and self-assembly. By utilizing a patterned template with controlled wettability, precise manipulation of LHP crystal formation is achieved, …

Ultrashort Pulsed Laser Treatment Is Effective At Sterilizing Metal Surfaces For Planetary Protection, Kaleb Mcquillan

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

To prevent forward contamination from microbes aboard spacecraft intended for exploration of solar system bodies there is a need for effective sterilization methods. However, current techniques are both time-consuming and expensive. For example, dry heat sterilization requires removal from the assembly site and several days of treatment. Furthermore, some components such as optics and electronics are not compatible with current sterilization techniques. In this thesis, a novel femtosecond laser surface processing technique for the rapid sterilization of spacecraft hardware is reported. Femtosecond lasers produce extremely high photon fluxes (10²⁹ photons/s*cm², ~0.03 J/cm²) in extremely short …

Optimization Of Customer Service And Driver Dispatch Areas For On-Demand Food Delivery, Jingfeng Yang, Hoong Chuin Lau, Hai Wang

Research Collection School Of Computing and Information Systems

With the rapid development and popularization of mobile and wireless communication technologies, on-demand food delivery (OFD) platforms have been able to connect restaurants, customers, and drivers in real time, drastically changing dining and food delivery services. Motivated by the critical need for supply and demand management in the on-demand food delivery market, we focus on the optimization of customer service area and driver dispatch area for on-demand food delivery services. Specifically, for each restaurant, the platform needs to decide the (1) customer service area (CSA), i.e., the surrounding area within which customers can see the restaurant’s information and order food …

Path-Choice-Constrained Bus Bridging Design Under Urban Rail Transit Disruptions, Yiyang Zhu, Jian Gang Jin, Hai Wang

Research Collection School Of Computing and Information Systems

Although urban rail transit systems play a crucial role in urban mobility, they frequently suffer from unexpected disruptions due to power loss, severe weather, equipment failure, and other factors that cause significant disruptions in passenger travel and, in turn, socioeconomic losses. To alleviate the inconvenience of affected passengers, bus bridging services are often provided when rail service has been suspended. Prior research has yielded various methodologies for effective bus bridging services; however, they are mainly based on the strong assumption that passengers must follow predetermined bus bridging routes. Less attention is paid to passengers’ path choice behaviors, which could affect …

Engineering The Properties Of Magnesium Aluminate Spinel Through Solid State Solutions, Robin Conner

All Theses

Magnesium aluminate spinel solid state solutions were prepared via the coprecipitation method and calcined in air at 900 °C for 2 h. The manipulation of magnesium aluminate spinel’s microstructure through the formation of solid state solutions with zinc and gadolinium substituting for magnesium was investigated. X-ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) confirmed the formation of a single cubic crystalline phase. The luminescence properties were investigated by radioluminescence (RL) under X-ray excitation and thermoluminescence (TL) measurements. In the case of zinc, all concentrations of the solid state solutions showed similar luminescence with bands at …

Genetically-Encoded Optical Barcodes For Single-Cell Analysis, Daniel Pritko

All Theses

Cell barcodes are capable of being used to answer many different biological questions. They have been used to track the lineage of cells to identifying the function of a gene. While there are multiple different methods to creating cell barcodes, they are limited in their scalability and application. In a previous publication we propose and computationally prove an optical single-cell barcoding method that bridges fast and scalable readouts with the benefits of genetic encoding. In this approach fluorescent proteins (fps) are combined to form fluorescent barcodes that can then be analyzed using a spectral flow cytometer. Here, we test the …

Degradation Products And Microbial Communities Associated With The Conversion Of Five Long-Chain Fatty Acids Relevant For Anaerobic Co-Digestion Of Fog With Sludge, Claire Funk

All Theses

Anaerobic digestion is a technology that allows wastewater treatment plants to convert sludge to energy by recovering the biogas produced during the breakdown of proteins, carbohydrates, and lipids. Furthermore, adding fats, oils, and greases (FOG) through co-digestion with wastewater sludge can increase energy production as lipids have a higher methane yield than proteins and carbohydrates. However, adding FOG can also lead to operational problems in the digester due to the potential accumulation of certain long-chain fatty acids (LCFAs). Current research is limiting in the degradation pathways of prominent LCFAs in FOG and the microbial communities responsible for their degradation

The …

Extraction Of Neutron-Gamma Irradiated Diffusion Pump Oils, Cooper L. Tillman

All Theses

This work successfully demonstrates solvent extraction methods for separation of oil from the by-products when two commercially available vacuum pump oils were exposed to an intense neutron and gamma-ray radiation environment. Nuclear fusion power at a commercial scale has accelerated the need for radiation resistant vacuum technology, such as oil-based diffusion pumps. Polyphenyl ether and aromatic silicone oils were irradiated at the Rhode Island Nuclear Science Center (RINSC) up to MGy absorbed doses with neutron and gamma-ray radiation. Solvent extractions were performed using hexane and isopropanol to characterize the oil extraction as a function of total absorbed dose. The by-products …

Flow-Shop Scheduling Optimization Through Discrete-Event Simulation And Neural Networks., Jesus Ricardo Herrera Garfio

Open Access Theses & Dissertations

Industrial developments over the past few decades have transformed manufacturingprocesses, emphasizing the necessity for efficient scheduling systems. The shift from manual scheduling to automated and optimized systems has underscored the need for innovative approaches to improve production efficiency. Scheduling optimization of manufacturing systems is critical to improve operational efficiency. Typically, these scheduling problems become challenging because they involve coordinating various production tasks, resource management, and makespan minimization. These challenges are particularly evident in flow-shop manufacturing systems, where the operation sequencing significantly impacts overall performance. The main objective of this manuscript is to present the methodology followed to optimize the schedule …

Bi-Modal Excitation Of A Supersonic Rectangular Jet, Benjamin Malczewski

Doctoral Dissertations and Master's Theses

This work addresses the issue of supersonic rectangular jet noise via bi-modal excitation. A Mach 1.5 heated rectangular jet with a 2:1 aspect ratio is considered. Theoretical work is presented in which a Reduced-Order Model (ROM) is used in conjunction with the Linearized Euler Equations to predict the nonlinear growth and decay of various frequencies due to the interaction between harmonically related modes and the mean flow. Scope is limited to a symmetric disturbance. The case of no interaction is used to help identify a dominant coherent structure, referred to as “f”. For the symmetric disturbance, a Strouhal number of …

Technology Acceptance Of Virtual Reality For Aircraft Maintenance Training, Lusine Carlsson

Doctoral Dissertations and Master's Theses

A study was conducted to investigate Virtual Reality (VR) technology acceptance for aircraft maintenance training by student mechanics. The study employed a survey methodology using the extended Technology Acceptance Model (TAM) as the theoretical framework. Participants were student mechanics from Federal Aviation Administration (FAA) approved aircraft maintenance schools within the United States. The study attempted to address how the variables of perceived usefulness (PU) and perceived ease of use (PEU) influence the students' behavioral intention (BI) to use VR technology for aircraft maintenance training, and how external variables of self-efficacy (SE), perceived enjoyment (PE), perceived health risk (PHR), performance expectancy …

Sustainable Waste-To-Bioproducts Engineering Center Laboratory Safety Project, Claudine Mock

All Graduate Reports and Creative Projects, Fall 2023 to Present

Laboratory accidents are common in teaching and research labs; these accidents can be injurious or even fatal. The consequences of each type of laboratory accident are different based on the activities performed and the hazardous materials used in each facility. However, the most common issue related to laboratory accidents is the lack of proper safety measures (e.g., poor handling of hazardous materials, not reporting incidents immediately, etc.). This project aimed to establish and strengthen best practices and procedures to ensure laboratory safety at the Utah State University Sustainable Waste-to-Bioproducts Engineering Center. To achieve this goal, different practices and measures were …

Method Development For The Extraction And Analysis Of Per- And Polyfluoroalkyl Substances (Pfas) In Wastewater And Biosolids, Victoria Krull

All Graduate Theses and Dissertations, Fall 2023 to Present

Per and poly-fluorinated alkyl substances (PFAS) are manufactured chemicals that have water and grease repellant properties and do not readily biodegrade. PFAS are present in many consumer products and end up in waste systems and the environment. Studies have shown that PFAS can have adverse health effects on humans and animals.

There are many challenges to processing and analyzing samples containing PFAS including: adsorption of PFAS to equipment, contamination from equipment containing PFAS, and the high sensitivity needed to analyze for PFAS in the parts per trillion detection range. The United States Environmental Protection Agency (EPA) has been developing methods …

Settingsorder Article Reprints Open Accessarticle A Model To Account For The Effects Of Load Ratio And Hydrogen Pressure On The Fatigue Crack Growth Behavior Of Pressure Vessel Steels, Ashok Saxena, Kip O. Findley

Mechanical Engineering Faculty Publications and Presentations

A phenomenological model for estimating the effects of load ratio R and hydrogen pressure P_H2 on the hydrogen-assisted fatigue crack growth rate (HA-FCGR) behavior in the transient and steady-state regimes of pressure vessel steels is described. The "transient regime" is identified with crack growth within a severely embrittled zone of intense plasticity at the crack tip. The "steady-state" behavior is associated with the crack growing into a region of comparatively lower hydrogen concentration located further away from the crack tip. The model treats the effects of R and P_H2 as being functionally separable. In the transient …

Multimodal Boiling Dataset With Synchronized Acoustic, Optical, And Thermal Measurements Under Steady-State And Transient Heat Loads, Hari Pandey, Changgen Li, Han Hu

Mechanical Engineering Faculty Publications and Presentations

Boiling is a high-performance heat dissipation process that is central to electronics cooling and power generation. However, there exists a practical limit of boiling heat transfer known as the critical heat flux (CHF), beyond which significant performance degradation is observed. Understanding the physical mechanism that triggers CHF is essential to meet the increasing cooling demands driven by power densification and device miniaturization. However, the high dimensionality, stochasticity, and dynamicity of the boiling process have led to strong challenges in the experimental characterization and modeling of boiling CHF. As such, high-frame rate, high-resolution, multi-physics boiling datasets are critical to advancing the …

Synthesis Of Silica-Encapsulated Myristic Acid Phase-Change-Assisted Nanocapsules For Thermal Management Applications, Muhammad Ghufran, David Huitink

Mechanical Engineering Faculty Publications and Presentations

Myristic acid-based silica (MA/SiO₂) nano-encapsulated phase change materials (NePCMs) were synthesized by the sol–gel process. Five different samples of the MA/SiO₂ nanocapsules were prepared by varying the mass of the myristic acid. The nanocapsules were characterized by Fourier transform infrared spectrophotometer (FTIR), X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX), and dynamic light scattering (DLS). These characterization techniques confirmed the successful encapsulation of the myristic acid inside the silica shell. The maximum latent heat was found to be 114.46 J/g for the sample which was prepared with 25 g myristic …

Fatigue Performance Of 3d-Printed Poly-Lactic-Acid Bone Scaffolds With Triply Periodic Minimal Surface And Voronoi Pore Structures, Hamed Bakhtiari, Alireza Nouri, Majid Tolouei-Rad

Research outputs 2022 to 2026

Bone scaffolds serve a crucial role in tissue engineering, particularly in facilitating bone regeneration where natural repair is insufficient. Despite advancements in the fabrication of polymeric bone scaffolds, the challenge remains to optimize their mechanical resilience. Specifically, research on the fatigue behaviour of polymeric bone scaffolds is scarce. This study investigates the influence of pore architecture on the mechanical performance of poly-lactic-acid (PLA) scaffolds under quasi-static and cyclic compression. PLA scaffolds with a 60% porosity were fabricated using extrusion-based 3D printing in various designs: Gyroid, Lidinoid, Fischer–Koch, IWP, and Voronoi. Results demonstrated that Gyroid scaffolds had the highest compressive strength …

Magnetization And Age Of Ca. 544 Ma Syenite, Eastern Canada: Evidence For Renewal Of The Geodynamo, Tinghong Zhou, Mauricio Ibañez-Mejia, Richard K. Bono, Rory D. Cottrell, Wouter Bleeker, Kenneth P. Kodama, Wentao Huang, Eric G. Blackman, Francis Nimmo, Aleksey Smirnov, John A. Tarduno

Michigan Tech Publications

The ca. 565 Ma Ediacaran geodynamo was highly unusual, producing an ultralow field 10 times weaker than present-day value of 8 x 1022 A m2. A ∼5 times rise in field strength is seen in time-averaged single crystal paleointensity data of ca. 532 Ma Early Cambrian anorthosites of Oklahoma (USA). The field increase could record the onset of inner core nucleation predicted by thermal evolution and numerical dynamo models. Here, we examine the renewal of the geodynamo through zircon U-Pb geochronology and single crystal paleointensity studies of plagioclase from the Chatham-Grenville syenite intrusion in the Grenville Province (Canada). U-Pb data …

Segac: Sample Efficient Generalized Actor Critic For The Stochastic On-Time Arrival Problem, Honglian Guo, Zhi He, Wenda Sheng, Zhiguang Cao, Yingjie Zhou, Weinan Gao

Research Collection School Of Computing and Information Systems

This paper studies the problem in transportation networks and introduces a novel reinforcement learning-based algorithm, namely. Different from almost all canonical sota solutions, which are usually computationally expensive and lack generalizability to unforeseen destination nodes, segac offers the following appealing characteristics. segac updates the ego vehicle’s navigation policy in a sample efficient manner, reduces the variance of both value network and policy network during training, and is automatically adaptive to new destinations. Furthermore, the pre-trained segac policy network enables its real-time decision-making ability within seconds, outperforming state-of-the-art sota algorithms in simulations across various transportation networks. We also successfully deploy segac …

Fuel-Saving Route Planning With Data-Driven And Learning-Based Approaches: A Systematic Solution For Harbor Tugs, Shengming Wang, Xiaocai Zhang, Jing Li, Xiaoyang Wei, Hoong Chuin Lau, Bing Tian Dai, Binbin Huang Huang, Zhe Xiao, Xiuju Fu, Zheng Qin

Research Collection School Of Computing and Information Systems

In recent years, there are trends toward cleaner port environments through enforcement by imposed legislation. Transit optimisation of fuel-based port service boats like harbour tugs has emerged as a critical task to reduce fuel consumption and carbon emission. In this paper, an innovative learning-based method, comprising a Reinforcement Learning (RL) model together with a fuel consumption prediction model, was proposed to formulate fuel-saving transit routes. Firstly, an ensemble model is established by combining a Long Short-Term Memory (LSTM) model with a Multilayer Perceptron (MLP) model, predicting fuel use based on tugboat movement and environment factors. Subsequently, an innovative RL based …

High-Quality Single-Step Growth Of Gaas On C-Plane Sapphire By Molecular Beam, Emmanuel Wangila, Calbi Gunder, Mohammad Zamani-Alavijeh, Fernando Maia De Oliveira, Serhii Kryvyi, Aida Sheibani, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo

Physics Faculty Publications and Presentations

We report on the growth of high-quality GaAs semiconductor materials on an AlAs/sapphire substrate by molecular beam epitaxy. The growth of GaAs on sapphire centers on a new single-step growth technique that produces higher-quality material than a previously reported multi-step growth method. Omega-2theta scans confirmed the GaAs (111) orientation. Samples grown at 700 °C displayed the highest crystal quality with minimal defects and strain, evidenced by narrow FWHM values of the rocking curve. By varying the As/Ga flux ratio and the growth temperature, we significantly improved the quality of the GaAs layer on sapphire, as compared to that obtained in …

Slurry Infiltrated Low-Quality Construction And Demolition Coarse Aggregate Waste In Concrete - A Sustainable Construction, Vishnu Vijayan, Sanjay Kumar Shukla, K. M. Mini

Research outputs 2022 to 2026

Exponential growth in infrastructure projects, stimulated by emerging sophisticated technologies have been instrumental in the salutary proliferation of the construction sector, globally. An indubitable adversity of the rapid boom in the construction industry has been the rampant cumulative fallout of burgeoning waste during the demolition and construction phases of restoration. The current study explored the propriety of replacing natural coarse aggregate by low-quality recycled coarse aggregates (RCA) with varying proportions, along with silica fume (SF) and polypropylene (PP) fibers as admixtures, for the preparation of concrete. As the quality of RCA is determined by the history of its parent demolished …

Towards Load-Bearing Biomedical Titanium-Based Alloys: From Essential Requirements To Future Developments, Yu-Wei Cui, Liqiang Wang, Lai-Chang Zhang

Research outputs 2022 to 2026

The use of biomedical metallic materials in research and clinical applications has been an important focus and a significant area of interest, primarily owing to their role in enhancing human health and extending human lifespan. This article, particularly on titanium-based alloys, explores exceptional properties that can address bone health issues amid the growing challenges posed by an aging population. Although stainless steel, magnesium-based alloys, cobalt-based alloys, and other metallic materials are commonly employed in medical applications, limitations such as toxic elements, high elastic modulus, and rapid degradation rates limit their widespread biomedical applications. Therefore, titanium-based alloys have emerged as top-performing …

In-Situ Micro-Ct Analysis Of Deformation Behavior In Sandwich-Structured Meta-Stable Beta Ti−35nb Alloy, Yu Jing Lui, Zi Lin Zhang, Jin Cheng Wang, Xiang Wu, Xiao Chun Liu, Wei Ying Huang, Lai Chang Zhang

Research outputs 2022 to 2026

Beta Ti−35Nb sandwich-structured composites with various reinforcing layers were designed and produced using additive manufacturing (AM) to achieve a balance between light weight and high strength. The impact of reinforcing layers on the compressive deformation behavior of porous composites was investigated through micro- computed tomography (Micro-CT) and finite element method (FEM) analyses. The results indicate that the addition of reinforcement layers to sandwich structures can significantly enhance the compressive yield strength and energy absorption capacity of porous metal structures; Micro-CT in-situ observation shows that the strain of the porous structure without the reinforcing layer is concentrated in the middle region, …

Transient Heat Transfer To Rolling Or Sliding Drops On Inclined Heated Superhydrophobic Surfaces, Joseph Furner, Daniel Maynes, Brian D. Iverson, Julie Crockett

Faculty Publications

The thermal transport to drops that roll or slide down heated superhydrophobic surfaces is explored. High-speed infrared imaging is performed to provide time-resolved measurement of the heat transfer to the drop. Data are obtained for drops moving along smooth hydrophobic and structured superhydrophobic surfaces. Both post and rib style structures with surface solid fractions ranging from 0.06 to 1.0 are considered. The inclination angle of the surfaces was varied from 10 deg to 25 deg, and the drop volume was varied from 12 to 40 µL. The measurements reveal that the drop speed is a strong function of both the …

A Position Allocation Approach To The Battery Electric Bus Charging Problem, Alexander Brown

All Graduate Theses and Dissertations, Fall 2023 to Present

With an increasing adoption of Battery Electric Bus (BEB) fleets, developing a reliable charging schedule is vital to a successful migration from their fossil fuel counterparts. In this work, a BEB charging scheduling framework that considers fixed route schedules, multiple charger types, and battery dynamics is modeled as a Mixed Integer Linear Program (MILP). The MILP is modeled after the Berth Allocation Problem (BAP) in a modified form known as the Position Allocation Problem (PAP). The optimization coordinates BEB charging to ensure that each vehicle remains above a specified charge percentage. The model also minimizes the total number of chargers …