Digital Commons Network^™

A New Proposed Coding Method For Steganography Purpose, Suhad Kadhem

Engineering and Technology Journal

Transferring data in a safe way is one of the things that have been of interest since ancient times. Data hiding or steganography is a method used to protect the data during its transmission. Coding is a method to represent the data in another shape, so a high level of security is achieved by using coding and hiding data together. The proposed method is a hybrid between coding and hiding, but this paper focuses on proposed a data coding part only, such that the cover text (that used for information hiding) will be used to extract private information between the …

The Effect Of The Number Of Key-Frames On The Facial Emotion Recognition Accuracy, Suhaila N. Mohammed, Alia K. Abdul Hassan

Engineering and Technology Journal

Key-frame selection plays an important role in facial expression recognition systems. It helps in selecting the most representative frames that capture the different poses of the face. The effect of the number of selected keyframes has been studied in this paper to find its impact on the final accuracy of the emotion recognition system. Dynamic and static information is employed to select the most effective key-frames of the facial video with a short response time. Firstly, the absolute difference between the successive frames is used to reduce the number of frames and select the candidate ones which then contribute to …

Speaker Recognition Systems In The Last Decade – A Survey, Ahmed M. Ahmed, Aliaa K. Hassan

Engineering and Technology Journal

Speaker Recognition Defined by the process of recognizing a person by his\her voice through specific features that extract from his\her voice signal. An Automatic Speaker recognition (ASP) is a biometric authentication system. In the last decade, many advances in the speaker recognition field have been attained, along with many techniques in feature extraction and modeling phases. In this paper, we present an overview of the most recent works in ASP technology. The study makes an effort to discuss several modeling ASP techniques like Gaussian Mixture Model GMM, Vector Quantization (VQ), and Clustering Algorithms. Also, several feature extraction techniques like Linear …

A Proposed Speaker Recognition Method Based On Long-Term Voice Features And Fuzzy Logic, Iman H. Hadi, Alia K. Abdul-Hassan

Engineering and Technology Journal

Speaker recognition depends on specific predefined steps. The most important steps are feature extraction and features matching. In addition, the category of the speaker voice features has an impact on the recognition process. The proposed speaker recognition makes use of biometric (voice) attributes to recognize the identity of the speaker. The long-term features were used such that maximum frequency, pitch and zero crossing rate (ZCR). In features matching step, the fuzzy inner product was used between feature vectors to compute the matching value between a claimed speaker voice utterance and test voice utterances. The experiments implemented using (ELSDSR) data set. …

Improving The Fpga Radio Design Cycle: Implementing Dvb-S2 Modulation Using Verilator And Gnu Radio, Seth Pellegrino

Dissertations and Theses

In embedded digital radio systems, a central challenge is meeting the real-time throughput required to process the samples--especially for space-bound ultra-wideband SDRs which must handle more than 100 Gbps entirely onboard. An FPGA's programmable logic offers sufficient potential, but realizing a particular radio flow is a project usually fraught with defects and long turnaround times. We simulated Verilog modules in a custom harness that adapted a Verilated model to GNU Radio, which allowed for breaking down a complicated radio flow (here, DVB-S2 modulation) into a series of well-bounded problems each with clear criteria for success. The framework, built on open …

Impact Of Gas Interactions With Nano Porous Geological Material In The Presence Of Water Vapor, Matthew D. Powell

Chemical and Biological Engineering ETDs

Predicting gas transport in nanoporous geological material requires understanding competitive adsorption and transport under humid conditions. However, most adsorption studies rely on single-component equilibrium measurements that do not capture these effects. This dissertation develops an experimental methodology to directly quantify multicomponent gas adsorption and breakthrough behavior under controlled relative humidity. The method was first applied to the Kr/Xe–N2–H2O system, where it resolved competitive adsorption behavior in humid porous media and produced a bivariate model relating noble gas adsorption to noble gas partial pressure and water saturation. The methodology was then extended to the CO2–N2 H2O system. Results showed that water …

Multiscale Network Modeling Of Native And Modified Photosynthetic Light-Harvesting Complexes, Zane E. Armijo

Chemical and Biological Engineering ETDs

Photosynthetic light-harvesting complexes harvest solar energy and direct electronic excitations toward reaction centers with exceptional efficiency. This dissertation models the Fenna--Matthews--Olson complex of green sulfur bacteria, coupled to the PscA1 reaction center, as a chromophoric network. Forster resonance energy transfer theory, validated against numerically exact hierarchical equations of motion, was implemented in kinetic Monte Carlo simulations to resolve fine-grained excitation-transport pathways. The predicted charge-transfer efficiency of 77\% agrees with experiment, with the FMO2 monomer and its gateway pigment governing interfacial transfer. Systematic single, multi, and symmetry-preserving site removals, interpreted through Mobius inversion, identify critical pigments and show that cooperative effects …

Developing Simulation To Improve G3p3 Efficiencies, Andrew Gaudette

Mechanical Engineering ETDs

Concentrated solar power (CSP) systems offer a promising method of renewable energy generation by using heliostats to focus sunlight onto a falling particle receiver. At the National Solar Thermal Testing Facility (NSTTF), particles absorb and store solar energy for later power generation. A major source of efficiency loss is wind-driven particle escape through the receiver aperture. This thesis develops computational fluid dynamics (CFD) simulations to characterize wind flow around the G3P3 falling particle receiver and support future wind mitigation strategies. Numerical studies were conducted to establish an appropriate simulation methodology. Iteration studies showed that 2,000 iterations were sufficient for convergence, …

Control Of Reshock In A Shock Tube, Alexander Sweis

Mechanical Engineering ETDs

Reshocks can pose a threat to the structural integrity of structures and buildings. While incident shock waves pose larger threats, the study of reshocks and reshock attenuation is important to consider. This thesis investigates methods for controlling and attenuating reshock strength within a shock tube through material-based damping and modifications to baffle box geometric configurations. Experiments are performed using a custom-built shock tube in the University of New Mexico fluid mechanics laboratory. Four baffle box configurations are examined: a foam-lined configuration, a foam-lined configuration with ”egg crate-like” textured foam, an empty (no foam) configuration, and a configuration which incorporates a …

Design And Feasibility Study Of An Air-Cooled Reactor Cavity Cooling System For Fluoride-Salt-Cooled High-Temperature Reactors, Alexandra D. Martinez

Nuclear Engineering ETDs

Licensing efforts for Fluoride-Salt-Cooled High-Temperature Reactors (FHRs) are dependent on passive safety systems designed for decay heat removal, yet no prior study has evaluated an air-based Reactor Cavity Cooling System (RCCS) for this role. This thesis addresses that gap by determining whether an air-cooled RCCS can be designed to passively remove post-shutdown decay heat from the Mk 1 FHR. An RCCS configuration was developed and sized using a one-dimensional lumped-parameter design methodology, then evaluated through system-level thermal-hydraulic modeling in RELAP5-3D under a conservative, lower-bound post-shutdown transient. The analysis characterizes the radial heat-transfer pathways from the FHR core to the RCCS …

Development Of Dynamic Proof-Mass Configurations For Broadband Piezoelectric Energy Harvesting, Nico E. Galarza

Electrical and Computer Engineering ETDs

The purpose of this thesis is to investigate and develop dynamic proof-mass configurations for broadband piezoelectric energy harvesting. Conventional piezoelectric energy harvesters are typically limited by narrow operating bandwidths, restricting their performance under variable-frequency excitation. This research presents the design, fabrication, and experimental evaluation of multiple proof-mass concepts intended to increase the usable frequency range of cantilever-based piezoelectric energy harvesters. Several dynamic mass configurations were developed using additive manufacturing techniques and integrated with commercially available piezoelectric cantilevers. Experimental testing was conducted under controlled vibration conditions to characterize voltage response, resonant behavior, and bandwidth performance. The results demonstrate that dynamic proof-masses …

Synergizing Crowd Collaboration: Enhancing Crowdsourcing Matching Via Integration Of Matching Theory And Coalition Games, Rowan Aengus Kinney

Electrical and Computer Engineering ETDs

This paper tackles the challenges inherent in crowdsourcing dynamics by introducing the CROWDMATCH mechanism. Aimed at enabling crowdworkers to strategically select suitable crowdsourcers while contributing information to crowdsourcing tasks, CROWDMATCH considers incentives, information availability and cost, and the decisions of fellow crowdworkers to model the utility functions for both the crowdworkers and the crowdsourcers. Specifically, the paper presents an initial Approximate CROWDMATCH mechanism grounded in matching theory principles, eliminating externalities from crowdworkers’ decisions and enabling each entity to maximize its utility. Subsequently, the Accurate CROWDMATCH mechanism is introduced, being initiated by the outcome of the Approximate CROWDMATCH mechanism, and employing …

Investigating Light-Matter Interactions In Low-Dimensional Silicon Carbide, Nishan Shrestha

Mechanical Engineering ETDs

Recent advances in materials science have transformed the study and application of low-dimensional materials, with two-dimensional (2D) systems and nanoscale structures exhibiting properties beyond their bulk counterparts. Despite significant progress in materials such as graphene and silicon, the nanoscale exploration of silicon carbide (SiC) remains relatively underdeveloped, despite its critical importance in photonics and electronics and high temperature applications. Motivated by the transformative potential of nanoscale material design and the technological importance of SiC, this dissertation investigates structure and properties of low-dimensional silicon carbide structures. It explores the synthesis and optical properties of SiC nanosheets and nanowires using a variety …

Simulations Of Atmospheric Pressure Streamer Discharges: Mechanisms Of Streamer Propagation And Related Physics, Dejan Nikic

Electrical and Computer Engineering ETDs

Gas discharge simulations are performed with particular focus on photoionization process in a positive streamer discharge. The effects of this process are investigated by isolating the change in photoionization mean free path (MFP) and keeping the additional processes constant. Furthermore, comparison are made between various effects of simulation parameters, such as initial conditions, geometry extent, simula- tion particle count etc. All of these simulations are performed using a modern Direct Simulation Monte Carlo Particle-in-Cell (DSMC-PIC) code developed by Sandia Na- tional Laboratories. Large scale simulations including 1 cm and 5 cm electrode gaps are performed under standard atmospheric condition air. …

Computationally Tractable Methods For Constrained Optimal Control And Reachability Analysis Of Nonlinear Stochastic Dynamical Systems, Karthik Sivaramakrishnan

Electrical and Computer Engineering ETDs

Autonomous systems operating in uncertain environments require methods that can rigorously quantify safety, predict future behavior, and compute optimal decisions tractably. The unifying challenge is reasoning about uncertainty propagation in constrained dynamical systems. Motivated by autonomous spacecraft inspection, this dissertation develops model-based and data-driven methods for stochastic optimal control and stochastic reachability. First, it studies optimal on-orbit inspection of an uncertain tumbling spacecraft in both single-agent and multi-agent settings, and derives computationally efficient reformulations for exploring trade-offs among sensing, trajectory deviation, and fuel use. Second, it develops a probabilistically safe penalty-based reinforcement learning method that preserves gradient information during training …

Wildfire Impacts On Fluvial Hydrology From Watershed To National Scales, Paige G. Tunby

Civil Engineering ETDs

Wildfires alter the water quantity and quality in downstream river networks. Fires promote biodiversity, maintain habitat, and provide many ecosystem services in a fire-adapted landscape. However, changes in the natural fire regimes can alter ecosystem function and threaten the water security of impacted downstream communities. The magnitude, timing, and persistence of these impacts are difficult to predict due to the lack of high-resolution datasets with adequate coverage to evaluate spatiotemporal trends after a fire. This dissertation moves us beyond the status quo to evaluate post-fire fluvial responses across scales, from the event-scale impacts after the Hermit’s Peak-Calf Canyon wildfire in …

Effect Of Geothermal Conditions On Silica Flour Modified Wellbore Cement, Travis Benjamin Broadhurst

Civil Engineering ETDs

Considerable work has been conducted on modified wellbore cements, but a knowledge gap exists in the effects of downhole conditions on cement, especially tensile strength. In this study, a pressure vessel simulates representative downhole conditions (200⁰C, 1.5 MPa) with a reference solution for geothermal brine and naturally occurring geothermal gases. Samples are removed after 28-days for unconfined compressive strength testing, Brazilian tensile strength testing, elastic moduli measurement, and chemical analyses by X-ray diffraction and electron microprobe. Aqueous chemical analysis suggests multiple active reactions between the geothermal fluid and cement that are exacerbated by higher temperatures, but do not …

Mechanisms Of Advanced And Energy Efficient Wastewater Treatment Technologies, Derek Belka

Civil Engineering ETDs

This dissertation combines meta-omics, microbial ecology, and hydrodynamic analysis to explore mechanisms of enhanced biological phosphorus removal (EBPR) and aerobic granular sludge (AGS) in municipal wastewater treatment. Metagenomic and functional gene profiling of a laboratory sequencing batch reactor fed with amino acids and proteins, and with a low abundance of known polyphosphate-accumulating organisms (PAOs), revealed abundant Herpetosiphonaceae and Dermatophilaceae families possessed key PAO metabolic traits, including phosphate scavenging, anaerobic carbon pathways, and ppk2 gene variants aligned with established PAOs. These findings suggest amino acid-driven EBPR can occur via previously unrecognized taxa, challenging current engineering assumptions and highlighting the need for …

Investigating The Corrosion Behavior Of Stainless Steel 316 In Static Lead Lithium Eutectic Under Applied Stressed Conditions, Daniel E. Levario

Nuclear Engineering ETDs

As fusion power moves closer to feasibility, identifying structural materials compatible with breeding blanket environments remains a critical challenge. Lead-lithium eutectic (LLE) is a leading candidate breeder and coolant material due to its low melting point and combined tritium breeding and neutron multiplication capability. However, the corrosive nature of LLE toward structural steels at elevated temperatures must be characterized before these systems can be reliably deployed. This study investigates the corrosion behavior of Type 316 stainless steel in static LLE under applied stress conditions at 550°C using C-ring stress corrosion specimens. Post exposure analysis via optical microscopy, SEM, EDS, and …

Mapping And Modeling Threat-Evoked Brain States After Early Life Adversity, Taylor W. Uselman

Biomedical Sciences ETDs

Early life adversity (ELA) increases lifelong neuropsychiatric vulnerability. Yet how ELA reorganizes brain-wide activity and circuit coordination across later experience remains unclear. This dissertation tests the hypothesis that ELA alters adult brain-wide activity and responses to threat through disrupted coordination among neural systems that regulate emotional experience, including prefrontal-limbic and monoaminergic systems. Longitudinal manganese-enhanced MRI of adult mice exposed to standard or fragmented early care, combined with computational processing and statistical modeling, quantified brain states before, during, and long after innate predator threat. These studies established that acute threat evokes large-scale, distributed brain activity that evolves over time. ELA potentiates …

Algorithmic Sculpting Of Complex Fused Silica Surfaces For Nondestructive, Mode-Matched Cavity Quantum Electrodynamics: Adaptive Co2 Milling And Simulation-Guided Ultrafast Inscription, From Fiber Fabry-Perot Cavities To Monolithic Architectures, Meagan E. Parker

Optical Science and Engineering ETDs

Quantum sensors achieve exceptional measurement sensitivity through coherent, well-isolated quantum systems, but practical deployment is hindered by destructive readouts that require repeated state preparation and create long system dead times. Optical cavities enable continuous, nondestructive measurements with minimal back-action, yet integrating high-finesse cavities into scalable quantum devices remains limited by existing fabrication methods. To overcome these constraints, an adaptive CO₂ laser-milling platform was developed. Guided by glass thermodynamics and melt dynamics, this closed-loop system uses in-situ phase-shifting interferometry to sculpt complex fused-silica surfaces with sub-nanometer root-mean-square roughness. The platform was validated by fabricating extended-length fiber Fabry–Pérot cavities and monolithic micro-cavity …

Non-Traditional Rare-Earth-Doped Oxide Glass As A Gain Medium, Jared S. Tolliver

Optical Science and Engineering ETDs

There is a need for mid-infrared(MIR) lasers in defense, medical, and environmental monitoring. A large part of this technological development is the study of gain media. One class of materials of special interest is glasses with a low maximum phonon energy. These have the fiberization and broad spectral features of glass, whereas glasses with high maximum phonon energy exhibit higher rates of multi-phonon relaxation and can be opaque in the MIR, both of which are detrimental to laser operation. Recent advances in container-less processing have allowed for the study of new glasses that aren’t possible with conventional fabrication techniques. One …

Real-Time Waveform Synthesis For Rfsoc-Based Quantum Control Systems, Tiamike I. Dudley

Electrical and Computer Engineering ETDs

RFSoCs are gaining adoption in many labs for quantum control systems thanks to their compactness and affordability. Making full use of the many components on an RFSoC evaluation board is a challenging engineering problem that must be solved to realize scalable control systems. In this dissertation, I evaluate the performance of various RFSoC components in the context of quantum information science. I present two custom FPGA engines that accelerate and parallelize arbitrary waveform generation. The first engine can be instantiated many times to power low-speed DACs for ion-shuttling trap electrodes. The second engine synthesizes CPMG-XY8n dynamical decoupling pulse sequences on …

Modeling For You: A Personalized Approach To Residential Energy Simulation And Distributional Reinforcement Learning, Nestor Gabriel Pereira

Electrical and Computer Engineering ETDs

The growing complexity and uncertainty of residential energy use, driven by electric

vehicles and renewable technologies, demand more intelligent and robust

management systems. Traditional methods often fail when faced with unpredictable

electricity prices and user behavior. This dissertation addresses this gap by presenting

a novel personalized framework combining detailed household energy modeling with

a risk-aware reinforcement learning agent for appliance scheduling.

The first contribution is a probabilistic, bottom-up simulation model that captures

the interdependent behaviors of occupants, appliances, and electric vehicles to

generate realistic, high-fidelity load profiles. The second contribution is a lightweight,

tabular Distributional Q-Learning (D-QL) algorithm that schedules …

Multi-Robot Cooperative System For Complex Aerospace Manipulation Tasks: Theory And Application, Longsen Gao

Electrical and Computer Engineering ETDs

Multi-robot systems can extend manipulation capabilities beyond the limits of a single robot, particularly for tasks involving large, flexible, delicate, or free-floating payloads. Reliable cooperative manipulation, however, remains difficult when payload dynamics, contact geometry, compliance properties, deformation-induced forces, and external disturbances are only partially known, and when safety constraints must be enforced during physical interaction. This dissertation develops a two-layer control framework for resilient multi-robot manipulation under uncertainty, with emphasis on space servicing, satellite stabilization, aerial transportation, and cooperative manipulation of free-floating structures.

Enhanced Computational Modeling Of Photoionization And Streamer Formation, Anahita Alibalazadeh

Electrical and Computer Engineering ETDs

Photoionization is a key mechanism governing the formation and propagation of streamer discharges in air by generating electron-ion pairs ahead of the streamer front. Accurate and computationally efficient modeling of this non-local process is essential for reliable plasma simulations. However, the widely used Zheleznyak photoionization model relies on empirical assumptions and requires computationally expensive domain-wide integration.

This dissertation advances photoionization modeling in three ways. First, the classical integral model is enhanced by incorporating experimentally measured vacuum ultraviolet (VUV) emission spectra together with photoabsorption and photoionization cross-section data, enabling direct calculation of the photoionization source term as a function of pressure …

Developing A Dispersion Interferometer For Characterizing Power Flow Plasma Formation And Transport Studies, Nathan R. Hines

Electrical and Computer Engineering ETDs

Sandia's refurbished $Z$-pinch machine experiences persistent current loss in its post-hole convolute and inner magnetically insulated transmission line regions, widely attributed to low-density electrode plasmas whose formation and transport remain poorly constrained by existing diagnostics. This dissertation develops and validates a fiber-coupled, continuous-wave, second-harmonic orthogonally polarized dispersion interferometer for time-resolved measurements of electron areal density in millimeter-scale gaps. The diagnostic employs single-laser second-harmonic generation, non-steering differential phase control, and polarization-based phase retrieval to achieve sub-$10^{15}$~cm$^{-2}$ sensitivity, multi-hundred-megahertz bandwidth, and sub-$200$~$\mu$m effective cross-gap spatial resolution. Performance is benchmarked against a $94$~GHz interferometer on the UNM Helicon-Cathode plasma device and then fielded …

A Multidimensional Conceptual Framework For Supportive Outdoor Environments In Healthcare Settings, Mona Ali, Dalia A. Beheiry, Rowaida Kamel, Hammam Serageldin

HBRC Journal

The integration of supportive outdoor environments (SOEs) in healthcare settings has gained increasing attention for their potential to enhance patient recovery, support staff well-being, and contribute to holistic therapeutic outcomes. This scoping review examines design recommendations for inclusive outdoor environments in healthcare settings that impact user health and experience. Guided by the Joanna Briggs Institute (JBI) framework for scoping reviews, a comprehensive search was conducted across five databases (Google Scholar, PubMed, ScienceDirect, JSTOR, Sage), yielding 697 records. Following screening and applying the inclusion and exclusion criteria, 18 articles were selected for analysis. This scoping review identified consistent evidence linking outdoor …

Artificial Intelligence-Driven Framework For Enhancing Risk Management In The Architectural Design Process In Egypt, Ayman Ahmed Ezzat Othman, Nadia Mohamed Algheetany, Fatma Othman Alamoudy

Mansoura Engineering Journal

The construction industry is crucial for achieving the United Nations Sustainable Development Goals (SDGs). However, it faces significant risks during the Architectural Design Process (ADP) that affect project quality, cost, schedule, and sustainability. Due to its limitations, traditional risk management (RM) is often inadequate for addressing these challenges. This study aims to develop a novel Artificial Intelligence (AI) driven framework to enhance RM practices in Egyptian Architectural Design Firms (ADFs) through proactive RM and improved data-driven decision making. A mixed methods research approach was adopted to achieve the research objectives. A comprehensive literature review examined RM, ADP, and AI applications …

System Design And Validation Of Radio Astronomy Phased Arrays, Rebecca Shiu Haymore

Theses and Dissertations

Modern radio astronomy instruments require a wide field of view and high sensitivity. To this effect, BYU and Cornell University have developed the Advanced L-band Phased Array Camera for Astronomy (ALPACA), a fully cryogenic 69 dual-pol dipole array that produces 80 beams on the sky with 305 MHz instantaneous bandwidth centered on 1500 MHz. Integration testing has demonstrated proper beamforming and calibration, and ALPACA has been commissioned as an all-sky monitor to search for bright transients. Commissioning testing for ALPACA measured an element system noise temperature of 24 K and a beamformed system noise temperature of 17 K, making ALPACA …