Engineering Commons^™

Generation And Implementation Of Mixed Radiation From Laser Interactions On A Liquid Target, Benjamin M. Knight

Theses and Dissertations

The simultaneous generation of different forms of radiation from the same source is highly desirable but technically challenging. We present the generation of D-D fusion neutrons and >MeV-energy x-rays from extreme intensity (∼ 10¹⁹ W/cm² ), high repetition-rate (1 kHz) laser pulses on a thin liquid target. Total neutron fluxes of ∼ 105 neutrons/s and x-ray exposure rates up to ∼ 200 R/hr at 74 cm are measured. Evidence of D-D fusion is verified with a measurement suite including three independent neutron detection systems: an EJ-309 organic scintillator, a ³He proportional counter, and a set of 36 …

Investigating The Neurovascular Correlates Of Cognitive Function In Individuals With Spinal Cord Injury Using Functional Near-Infrared Spectroscopy, Donna Yali Chen

Dissertations

Individuals with spinal cord injury (SCI) have a 13 times greater risk of cognitive impairment than able-bodied individuals and commonly report symptoms of depression and anxiety. The reports of cognitive impairment in individuals with SCI are independent of concomitant brain injury. Although the direct cause of cognitive impairment in individuals with SCI is unknown, key contributors may include comorbid depression, chronic pain, anxiety, fatigue, brain injury, or cardiovascular dysfunction. Previous studies have focused on SCI at the level of the spinal cord but have under-investigated the supraspinal levels. Due to the lack of neuroimaging studies on SCI rehabilitation, it is …

A Micromagnetic Study Of Skyrmions In Thin-Film Multilayered Ferromagnetic Materials, Nicholas J. Dubicki

Dissertations

Magnetic skyrmions are topologically protected, localized, nanoscale spin textures in non-centrosymmetric thin ferromagnetic materials and heterostructures. At present they are of great interest to physicists for potential applications in information technology due to their particle-like properties and stability. In a system of multiple thin ferromagnetic layers, the stray field interaction was typically treated with various simplifications and approximations. It is shown that extensive analysis of the micromagnetic equations leads to an exact representation of the stray field interaction energy in the form of layer interaction kernels, a so-called 'finite thickness' representation. This formulation reveals the competition between perpendicular magnetic anisotropy …

Federated Learning Systems For Mobile Sensing Data, Xiaopeng Jiang

Dissertations

Federated Learning (FL) has emerged as a new distributed Deep Learning (DL) paradigm that enables privacy-aware training and inference on mobile devices with help from the cloud. This dissertation presents a comprehensive exploration of FL with mobile sensing data, covering systems, applications, and optimizations.

First, a mobile-cloud FL system, FLSys, is designed to balance model performance with resource consumption, tolerate communication failures, and achieve scalability. In FLSys, different DL models with different FL aggregation methods can be trained and accessed concurrently by different apps. In addition, FLSys provides advanced privacy-preserving mechanisms and a common API for third-party app developers to …

Data Driven Decision Making For Sustainable Planning And Operations Of Large Scale Networks, Bahareh Kargar

Dissertations

This dissertation explores data-driven decision-making networks, focusing on sustainable planning and operations for large-scale systems such as healthcare supply chains and power systems. One significant application in healthcare is the optimization of vaccine supply chains. An agent-based simulation-optimization modeling framework is developed to enhance the efficiency and sustainability of vaccine distribution. First, an agent-based epidemiological model of COVID-19 is extended to capture disease transmission dynamics and forecast the number of susceptible individuals and infections. Then, a sustainable vaccine supply chain considering the impacts of greenhouse gases is developed and integrated with the simulation model to minimize total costs and environmental …

Electrified Membrane For Water Treatment And Resource Recovery: Advancing Multiscale Strategies In Gas-Involving Reactions, Jianan Gao

Dissertations

Multifunctional, modular, and scalable water treatment technologies that operate without chemical additives are crucial for addressing global water pollution challenges. While traditional membrane-based separation processes are crucial for ensuring clean water supplies, they primarily focus on pollutant removal rather than on the upcycling of pollutants into valuable resources. Electrified membrane filtration presents a robust alternative, utilizing minimal or no chemical additives and harnessing electrical power to directly reduce contaminants or produce reactive oxidants or reductants on-site.

This dissertation is dedicated to the development of innovative electrochemically reactive membranes designed to address three major challenges: (1) the engineering of electrocatalysts with …

Microwave Catalysis-Enabled Membrane Processes For Microbial Inactivation, Fangzhou Liu

Dissertations

The COVID-19 pandemic has highlighted the urgent need for advanced technologies to combat virus transmission. Traditional membrane filtration technologies primarily serve as physical barriers, capturing pollutants but failing to inactivate microbial agents such as bacteria and viruses. These membranes typically target larger particles but are ineffective against sub-micrometer viral particles. Thus, there's a critical demand for membrane filtration processes that combine robust filtration with antifouling and reaction -enabled functions for efficient pathogen disinfection. This research explores a novel microwave-assisted membrane filtration process incorporating catalytic reactions to enhance microbial disinfection and prevent membrane fouling, offering a groundbreaking solution to global challenges …

Estimation Of Spo2 Levels And Heart Rate From Ppg Signals In The Presence Of Motion Artifacts, Chizhong Wang

Dissertations

In the rapidly advancing world of health technology, wearable devices are at the forefront, fundamentally changing how individuals monitor their health. The key to this transformation is photoplethysmography (PPG), a non-invasive optical method that measures blood flow variations through the skin by detecting changes in light absorption with each heartbeat. This capability makes PPG essential for monitoring vital signs such as heart rate and blood oxygen saturation(SpO₂). Furthermore, the utility of PPG signals has been extended beyond traditional health metrics to include human activity classification, offering a holistic perspective on an individual's physical health and activity levels, in …

Order-Picking Strategies And Efficiency Models For The Fulfillment Of Multi-Line E-Commerce Grocery Orders, Zijia Wang

Dissertations

The fulfillment process for Buy Online Pickup from Store grocery orders (BOPS-Grocery) is particularly challenging, given the large item count per order and the low-profit margins. This research investigates the BOPS-Grocery model and pursues the following objectives: (i) Defining and specifying the BOPS-Grocery fulfillment process. Differentiating the process from classical warehouse order picking., identifying performance objectives, and characterizing design options and facility layout. (ii) Modelling and developing order picking algorithms specific to the straight aisle section. Formulated as an order hatching problem with picker movement minimization. No order splitting, and (iii) modeling and developing order picking algorithms specific to the …

Collision Dynamics Of Compound Droplets In Microchannels: A Combined Numerical And Data-Driven Study, S M Abdullah Al Mamun

Dissertations

Understanding and predicting the hydrodynamic interactions of micron-scale droplets is crucial in a wide range of industrial and real-life applications, including microfluidics, pharmaceutics, drug delivery, food science, and enhanced oil recovery. These multi-phase and multi-scale phenomena are further complicated by the presence of core droplets of an immiscible fluid within shell droplets, known as compound droplets. The collisions and interactions of droplets in emulsions are influenced by various physical and geometric parameters, leading to distinct rheological and dynamic responses. This research employs numerical methods for a systematic parametric study of both simple and compound droplet pair collisions under confined shear …

Investigations On Structure-Related Properties Of Organic Inorganic Hybrid Materials For Multifunction, Anu Ranjani E Ms

Theses and Dissertations

Two-dimensional (2D) hybrid halide perovskites have become a versatile material in diverse applications like optoelectronics, lighting and display, magnetism, etc. These materials are often termed as layered hybrid halide perovskites (LHHPs) due to their unique structure with alternate organic and inorganic layers. The presence of insulating organic layers separates the inorganic perovskite slabs, creating a quantum-confined architectural configuration. This unique configuration endows these materials with a spectrum of distinctive functionalities, encompassing photovoltaics, lighting and displays, second harmonic generation, optical limiting, ferroelectricity, and ferromagnetism. The exceptional attribute is that a single LHHP can respond autonomously to external stimuli, such as changes …

Enhancing Security And Privacy For Smarter Environment Through A Robust Cyber-Physical System Framework, Ramya S

Theses and Dissertations

As digital computing paradigm and practices have emerged in disciplines, devices with processors and sensors were rudimentary, performing independent tasks with limited power. The first computer processors were slow, bulky and consuming high energy, as sensors in thermometers and pressure gauges provide original, independent measurements without effective communication, 1999. It often required powerful, energy-efficient processors and advanced sensors to enable seamless communication and sophisticated data processing.

These devices, since smart home systems to industrial automation tools, which continuously collect, analyse and share data via the internet, facilitating if real-time management, predictive maintenance, and improved seamless experience are used, transforming everyday …

Deep Learning Technique For The Classification Of Stress Among The Students Using Physiological Biomarkers With A Hybrid Feature Approach, Rajendran Vg

Theses and Dissertations

Adolescence is a crucial part in life, and the presence of stress, anxiety, depression, and health issues during this stage is a great concern. This research aims to analyze and predict the cognitive stress in students during the examination period using EEG biomarkers. In this study, raw EEG data is acquired under two different experimental conditions, before and after examination, from 14 subjects with an eight-channel Enobio device. After preprocessing of the EEG signal, the brain rhythms such as theta, alpha, and beta sub-band energies and EEG band ratios such as neural activity, heart rate, arousal index, vigilance index and …

Ai In Healthcare: Early Diagnosis Of Skin Cancer Using Medical Image Processing And Deep Neural Networks, Nirmala V

Theses and Dissertations

Several cancer types are commonly prevalent, and skin cancer is one among them, becoming even more widespread worldwide in the last few decades. To diagnose skin cancer at an early stage and obtain appropriate therapy to treat it, there is a demand to know more about the disease’s characteristics or severity. Skin cancer is caused mainly by various reasons, including damage of the sun or tanning beds by ultraviolet light exposure.

Failing to treat skin cancer might substantially impair an individual’s quality of life as the victim. They likely to experience physical issues linked with the deformities caused by psychological …

Effect Of Gas Tungsten Arc Welding Process Variants On The Microstructure And Properties Of Az31b Magnesium Alloy And 304hcu Austenitic Stainless Steel Welds, Srinivasan S

Theses and Dissertations

The automotive and aero sectors seek materials with high specific strength & specific stiffness for enhanced efficiency / emission control. Mg alloys, known for their low density, are used in the as-cast, and wrought forms, depending on the service requirements, and are predominantly used for non-loaded structural parts in varied engineering applications. Welding Mg alloys is of great interest to industry, not only for the fabrication of components but for the repair welding of casting as well. There has been considerable research in the fusion & solid-state welding of Mg alloys. Gas tungsten arc welding (GTAW) has often been preferred …

Investigation On Production, Kinetic Modelling, Downstream Processing, And Characterization Of Microbial Dextran Using Sucrose-Rich Alternate Feedstocks, Sameeha Syed Ar

Theses and Dissertations

Microbial exopolysaccharides (EPS) synthesized by microorganisms have a wide range of applications from thickener agents in the field of food to formulations in the field of pharmaceuticals. Owing to their rheological, structural, and physicochemical characteristics in addition to its biodegradability, low antigenicity, antioxidant activities, etc., several EPS have gained research focus in recent years. Dextran is one such example of EPS, which is synthesized by lactic acid bacteria (LAB). However, its production is limited to utilization of sucrose medium with a yield of 0.3-0.4 g dextran/ g sucrose. Hence, this thesis work focuses on dextran production using sucrose-rich alternate feedstocks …

Experimental Investigation And Evaluation Of Mechanical Properties And Microstructural Characterization On Chromium Molybdenum Steel Processed Through Laser Based Welding, Rakesh S

Theses and Dissertations

Creep Strength Enhanced Ferritic (CSEF) martensitic modified 9Cr-1Mo (P91) steel is extensively employed in fast breeder nuclear reactors and thermal power plants owing to its superior resistance to thermal fatigue and oxidation corrosion compared with other low-alloy steels. Despite its excellent high-temperature performance, the weldability of this steel remains a critical concern.

Conventional arc welding processes generate excessive heat input and complex thermal cycles, resulting in heterogeneous microstructures, retention of δ-ferrite, and subsequent degradation in service life. In contrast, high energy density beam welding techniques such as laser and electron beam welding offer precise thermal control and minimal heat-affected zones …

Remote Sensing Assessment Of Ionospheric Total Electron Content Over Thanjavur Gps Station Geomagnetic 2.91 N 152.22 E, Veera Kumar Maheswaran

Theses and Dissertations

A Global Positioning System (GPS) station for ionosphere studies was established during December 2019 in Thanjavur (Geographic 10.72◦ E, 79.01◦ N, Geomagnetic 2.91◦ N, 152.22◦ E). The study involved analysing Total Electron Content (TEC) data and correcting biases to estimate Slant Total Electron Content (STEC). STEC was then converted to Vertical Total Electron Content (VTEC), useful for space weather, navigation, surveying, and environmental monitoring.

During the course of our study, this Thanjavur station witnessed a Annular Solar eclipse of Dec-26, 2019. The Solar eclipses can impact ionospheric conditions, causing VTEC depletion. This study shows how the near-earth environment changes during …

Sustainable Valorization Of Woody And Herbaceous Biomass For Energy And Environmental Applications, Subramaniyasharma S

Theses and Dissertations

Pyrolysis is a thermochemical conversion method to produce gas and liquid fuels from lignocellulosic biomass. This process involves the thermal decomposition of organic compounds without oxygen. The vapors formed are rapidly condensed to yield a liquid product called bio-oil and a solid product called biochar.

In the present study, Sesame indicum (SI) (herbaceous agro residue) and Prosopis julifora (PJ) (woody biomass weed) were chosen as feedstocks for the pyrolysis process and the respective solid and liquid products were collected and characterized. The proportion of biomass pyrolysis products is significantly influenced by biomass composition and process conditions such as temperature, heating …

Motion Based Analysis Of Ultrasound Imaging For The Study Of Musculoskeletal Tissue Bio Mechanics, Ananth Hari R

Theses and Dissertations

Ultrasound image analysis plays an important role in diagnosing musculoskeletal injuries and monitoring rehabilitation exercises. The first and foremost step in this analysis involves segmentation of region of interest from the ultrasound images. The segmentation of the musculoskeletal tissues from the ultrasound images is challenging due to the inherent drawback present in ultrasound like : (1) Poor image quality due to image corruption by speckle noise, shadows, and attenuation. (2) Dis-continuous boundaries due to orientation dependence during the acquisition of image. (3) Low contrast between nearby anatomical structures. Hence in order to overcome these drawbacks, there is a need for …

Development Of Electrochemical Sensors For The Detection Of Pesticide Residues In Water, Indhu S

Theses and Dissertations

Intentional and unintentional events of pesticide poisoning and their accidental exposure have significantly raised the concerns of global organizations to classify these chemical compounds based on their toxicity, to assign permissible limits, and to appoint task force for periodic monitoring of their presence in water bodies.

In this context, researchers are continually seeking potential alternatives to develop water quality sensors with higher selectivity to obtain the desired performance during real-time assessment. Electrochemical sensors involving interface materials of distinguishing capacity at elevated matrix complexity are desirable. However, there remains a challenge in designing suitable techniques, methodologies, and appropriate validations to support …

Improving Fatigue Characteristics Of Cold Formed Low Carbon Steel, Venkatesan D

Theses and Dissertations

EN353 is a low carbon alloy steel, predominantly used in the manufacturing of heavy-duty gears, shafts, and pinions, especially crown wheel and pinions. It is usually carburized, hardened, and tempered to produce a hard, wear-resistant case. Heat- treated EN353 steel exhibits enhancement in ductility, toughness, strength, and hardness as the internal stresses get relieved in the material. Spheroidizing of medium and high carbon steel is a method of prolonged heating at a temperature below the eutectoid temperature, where pearlite, the lowest energy arrangement of steel, gets converted to ferrite and cementite.

The graphite content of steel assumes a spheroidal shape, …

Identification Of Delamination Defect In Fibre Reinforced Polymer Composite Tapered Plate Based On Vibration Measurement, Venkatesan M

Theses and Dissertations

Fibre-reinforced polymer (FRP) composite plates have been widely used in various engineering applications due to their high strength-to-weight ratio, corrosion resistance, and durability. Despite their many benefits, Delamination is a separation of the layers in composite material and can occur due to various factors such as impact, fatigue, and manufacturing defects. Identifying delamination in composite structures is crucial for ensuring safety and reliability. In this study, model-dependent vibration methods, which are an effective non-destructive technique, were utilised for delamination identification. The primary objective is to investigate the dynamic behaviour of delaminated thickness-tapered plates and develop a reliable methodology for delamination …

Abnormal Event Detection Using Hypergraph Based Multiple Objects Tracking Techniques In Surveillance Videos, Palanivel S

Theses and Dissertations

Abnormal event detection aims to identify the events that deviate from expected normal patterns. This work primarily focuses on detection of rare events in public places. The existing research challenges in a video-based surveillance systems for the vehicle have been analysed and presence of abnormal objects in traffic-oriented videos have been detected. A novel approach for event summarization and rare event detection has been proposed in this work. The key ingredient in this work is the incorporation of Hypergraph (HG) matching.

Despite the reasonable amount of success achieved by a large number of researchers over the globe, distinguishing important videos …

Investigation On Strength Durability And Crack Healing Efficiency Of Natural Fiber Reinforced Bacterial Concrete Under Various Exposures, Rajesh A

Theses and Dissertations

Concrete is the most broadly utilized construction material due to its availability and cost. It is more susceptible to cracks, allowing chemical substances and water to enter and deteriorate the materials over time, as well as affecting the durability properties of structures. In recent years, the use of bacteria and natural fibers in concrete has not only reduced cracks but also enhanced its strength and durability.

Microbial-induced carbonate precipitation (MICP) is highly acceptable in concrete to improve rheological and crack repair properties. In the current research isolated five bacteria from various locations and subjected to basic tests such as urease …

An Adaptive Hybrid Deep Learning Architecture For Providing Guaranteed Qos In 5g Cellular Networks, Rajilal Mv Ms

Theses and Dissertations

Wireless network systems must have effective resource allocation, particularly in the context of 5G networks when flexibility is needed to meet a range of network requirements. Resource allocation is essential in cellular network contexts to guarantee equitable access to customers, partners, and cellular service users. Since resource distribution determines network performance, it offers significant advantages when executed well. One of the biggest issues with 5G technology is resource allocation, particularly when it comes to the Quality of Service (QoS) for various applications. Resources in wireless networks include items like channels, power, and spectrum; these must all be apportioned according to …

Analysis Of Isotopic Effects On Hydrogen Oxidation, Jacob Carter Wilde

Theses and Dissertations

Tritium generation presents a significant hazard during operation of nuclear reactors and necessitates safety precautions in the case of a combustion incident. Accurate kinetic models should inform these safety precautions, however, reliable tritium data do not exist to generate such models. This work focuses on laminar flame speed, which is an important component of kinetic models. Current estimates based on established kinetic theories and experimental measurements of the other isotopes of hydrogen predict tritium to have a flame speed approximately 70% that of standard protium over a broad range of stoichiometries at one atmosphere in air. These estimates are based …

Machine Learning Framework For Predicting Reliability Of Solder Joints, Robert Lee Jones

Dissertations and Theses

This paper presents the techniques and framework to produce an explainable machine learning model for predicting the reliability of solder joints exposed to thermal cycle testing. While machine learning techniques have become prevalent for many engineering and data analysis tasks, the complexity of the model occludes valuable information which can be used to refine the data, tune model parameters, and aid in scientific discovery. By exposing the relationships within the model, users can have greater confidence in the use and employment of it. The purpose of this study is to show how useful relationships can be obtained from a traditional …

A Novel Perfused Contusion Spinal Cord Injury Model To Assess Rapid Mechanical Properties Changes After Blood Spinal Cord Barrier Breakdown, Laura De Marchi

Theses and Dissertations

Blood-spinal cord barrier (BSCB) disruption exacerbates the tissue damage caused by spinal cord injury (SCI), but the mechanisms and dynamics of how the barrier breakdown affects the mechanical properties of the tissue remain unclear. The perfused bovine ex vivo indentation injury model described here represents a new platform to investigate the short-term effects of altered blood flow and vascular permeability following traumatic spinal cord injury. Our results indicate that injured cords exhibit changes to bulk perfusion, as evidenced by laser speckle contrast imaging, in addition to decreased barrier function shortly after injury. Indentation tests that simultaneously simulate a crush injury …

Phosphorene As A Chemical Nanosensor For Volatile Organic Compound Vapours - A Dft Outlook, Saravanan S

Theses and Dissertations

Based on the density functional theory framework, the structural stability of phosphorene allotropes and its various nanostructures are ensured. The various allotropes of phosphorene and its nanostructures such as nanosheets, nanoribbon and nanotubes are used as adsorbing materials for various volatile organic compounds (VOCs) such as alcohols, chloroform, amines and aldehydes. The results of adsorption energy are used to confirm physisorption or chemisorption of VOCs on phosphorene. In addition, the charge transfer outcome suggests whether phosphorene is acting as acceptor or donor of electrons upon interaction of target VOCs.

The electronic attributes such as band structure, projected density of states …