Engineering Commons^™

Lrq-Solver: A Transformer-Based Neural Operator For Fast And Accurate Solving Of Large-Scale 3d Pdes, Peijian Zeng, Guan Wang, Haohao Gu, Xiaoguang Hu, Tiezhu Gao, Zhuowei Wang, Aimin Yang, Xiaoyu Song

Electrical and Computer Engineering Faculty Publications and Presentations

Solving large-scale PDEs on complex three-dimensional geometries remains a central challenge in scientific and engineering computing, often due to expensive pre-processing stages and high computational overhead. We present Low-Rank Query-based PDE Solver (LRQ-Solver), a physics-integrated deep learning framework for efficient CAE simulations of complex three-dimensional geometries in CAD-driven design analysis. Built upon the Parameter-Conditioned Lagrangian Modeling (PCLM) that embeds physical consistency into the learning process and the Low-Rank Query Attention (LR-QA) module that reduces attention complexity from O(N2) to O(NC2+C3) via covariance decomposition, LRQ-Solver supports multi-configuration analysis within iterative design workflows. On two benchmark datasets, it achieves a 28.6% error …

Degree Assortativity And Estimation Of Degree Distribution In A Contact Network Of People Who Inject Drugs, Peter Geissert

Dissertations and Theses

This dissertation analyzes data from a respondent driven sampling (RDS) study of people who inject drugs in Portland, OR.  The objective was to assess assumptions for the use of weighted estimators to estimate a population physical contact (syringe sharing) network degree distribution.

Visualization of degree distribution for social and physical networks, Kolmogorov-Smirnov tests of difference, and kernel tests of equivalence were used for comparison of distributions. Spearman's rho and GAM non-parametric regression models were used to test for association and assess non-monotonic relationship. The validity of Markov chain assumptions for RDS was assessed using a transition matrix, Markov chain graphs, …

Spatial Reconstructability Analysis: Information-Theoretic Modeling Of Categorical Raster Data, David Percy

Dissertations and Theses

This research focuses on the application of Reconstructability Analysis (RA), an information-theoretic machine learning (ML) methodology, to categorical spatial data in Geographic Information Systems (GIS). RA was developed in the systems community with applications including classification, prediction, pattern recognition, and decision analysis. RA is implemented in OCCAM (Organizational Complexity Computation and Modeling), a software suite developed at Portland State University that analyzes discrete data in tabular form, with observations in rows and variables in columns. While RA has been successfully applied to a variety of domains, no systematic application to georeferenced raster data arranged in regular grids has been previously …

Developing Field And Spaceflight Microscopy, Nikki Johnston

Dissertations and Theses

Designing for spaceflight favors the reduction of unnecessary features and cost-cutting, whether thisbe computation, hardware, or procedure. Resources are spent toward fortification and mission success over convenience. Such design goals paired with the relatively smaller budgets of academia lead us to do as much as we can in-house and use open-source as much as we can without compromising mission success. We also believe that thoroughly testing technology in extreme environments on earth is necessary for the success of a flight instrument. We focus on microscopy for life detection. I have spent my time here learning methods of hand-building microscopes to …

Advancing The Oresat Adcs: Design & Implementation Of An Open-Source Reaction Wheel System, Chris Kane-Pardy

Dissertations and Theses

Reaction wheels provide the primary means of precision attitude control for many CubeSat attitude determination and control systems by exchanging angular momentum with the spacecraft body. As the Portland State Aerospace Society's OreSat spacecraft transitioned from a 2U to a 3U configuration, the increased spacecraft inertia reduced the attitude control authority available from the legacy reaction wheel system. This thesis addresses that challenge through the redesign of the reaction wheel system and the development of a deterministic embedded controller and experimental framework for evaluating brushless motor commutation strategies under identical operating conditions.

The redesigned system combines an analytically sized flywheel, …

Intrinsic Memory In Digital Snns: Enhancing Performance On The Cart-Pole Task With Fractional-Order Dynamics, Niklas Karl Anderson

Dissertations and Theses

Researchers working with Spiking Neural Networks (SNNs) are faced with the challenge of identifying useful biologically plausible features for inclusion in neuron models. Prior research indicates that dynamics of fractional-order calculus, which impart a form of intrinsic memory, are a key feature of biological neurons. In this work, we present the development and usage of neural networks with intrinsic memory in application to the cart-pole task, a common benchmark for neural network performance. We found that usage of fractional-order neurons may allow for up to a 37.5% reduction in neural network size as compared to networks using a standard Leaky …

The Influence Of Urban Form On The Distribution Of Air Pollutants, Takin Khosrownia

Dissertations and Theses

Urban form exerts strong control on how pollution from outside a city is transported through the urban canopy and experienced at street level. This study uses the prognostic microclimate model ENVI-met to simulate an active pollutant released from an upwind rural highway and advected through an urban region represented by ten Local Climate Zone (LCZ) types. The cases share identical inflow and are isothermal, dry, and non-vegetated, so that differences among them are attributable to building morphology alone. PM2.5 is the primary exposure diagnostic. Its transport and ejection are characterized through plan-view contours, vertical plume sections, and spatially averaged streamwise …

Functionality Risk Assessment And Risk-Based Management For Critical Infrastructure Systems, Anteneh Zewdu Deriba

Dissertations and Theses

Critical infrastructure systems such as transportation networks serve as the lifelines of modern society, supporting economic activity and ensuring access to critical services. Their disruption under extreme events can produce consequences extending far beyond physical damage to individual assets. In transportation networks for instance, failures of critical assets such as bridges and tunnels can reduce accessibility of communities, limit freight capabilities for commerce, and increase travel distance and travel time of road users. These consequences associated with the system functionality loss are tied not only to the physical vulnerability and failure of individual assets, but also to the system configuration …

Measurement Of Pollution Emissions From Natural Gas Stoves: Preparation For An Induction Cooktop Intervention Study, Jessica Zanella Lorensi

Dissertations and Theses

Humans spend ∼90% of their time enclosed in buildings. Indoors environments can be a source of pollutant which can affect health and productivity. Appliances that combust fossil fuels indoors, like stoves, are a critical source of a range of pollutants, like carbon monoxide (CO) and nitrogen dioxide (NO₂). In the US, the usual cooking fuel is natural gas (NG), presented in more than 30% of households in the country. Some studies in the literature linked cooking pollutants, including those specific to gas combustion, to various health conditions, including heart and respiratory diseases. Nitrogen dioxide, for example, can be …

Storm Surge And Tides In Convergent Estuaries: The Case Of Extratropical Storm Merbok In Alaska, Steven Dykstra, Stefan Talke, David A. Jay, Matthew Lobo, Silvia Innocenti, Pascal Matte

Civil and Environmental Engineering Faculty Publications and Presentations

Coastal floods are composed of multiple drivers that interact with coastline geometries and are difficult to differentiate. To investigate the effects of basin shapes on storm surge and tides, we study the landfall of ex-Typhoon Merbok in the east Bering Sea, Alaska. Water levels at 34 stations are detided with a new tide wavelet tool, CWT_Multi (Lobo et al., 2024), and the spatial and temporal shifts in tides and surge are interpreted via long-wave theory. Results show nonstationary semiannual trends in tidal constituents due to ice effects and large interannual variability in mean-sea level (20-40 cm). After removing non-stationary tidal …

What Drives Blockchain Technology Adoption? A Meta-Analysis Across Tam, Tpb, And Utaut Frameworks, Amir Rahmani, Roohollah Ahmadi, Tugrul Unsal Daim, Mehdi Zamani, Dilek Ozdemir

Engineering and Technology Management Faculty Publications and Presentations

Research on blockchain adoption has expanded rapidly, with most studies conceptualizing adoption as behavioural intention. Technology adoption models, such as the Technology Acceptance Model (TAM), the Theory of Planned Behavior (TPB), and the Unified Theory of Acceptance and Use of Technology (UTAUT), are commonly applied to explore blockchain technology adoption (BTA). However, empirical results from the 12 hypotheses associated with these models remain fragmented and, at times, inconsistent, with limited comprehensive quantitative integration. To address this gap, the present study performs a meta-analysis to evaluate the degree and direction of these hypotheses systematically. In accordance with PRISMA guidelines, 149 quantitative …

Spatial Structure And Energy Content Of Wakes Behind Single And Arrayed Undulated Cylinders, Taiga Naomi Drucker-Boisvert, OndˇRej FerˇCák, Jérémie Auzoux, Sarah E. Smith, Zein Sadek, Rowan Moore, Christain T. Murphy, Trevor Dunt, Jennifer A. Franck, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Biologically inspired undulated cylinder geometries significantly influence wake structure and vortex-induced vibrations in turbulent flows, yet the underlying mechanisms are not fully understood. It is further unknown how these influences extend to multi-cylinder arrays, where interacting wakes accumulate and mix. This study examines the wake characteristics of an undulated cylinder and a smooth elliptic cylinder in single- and multi-cylinder array configurations, using particle image velocimetry and proper orthogonal decomposition (POD). Relative to the smooth elliptic cylinder, the undulated geometry induces pronounced spanwise-axial variability, characterized by enhanced near-wake mean momentum and weak far-wake signatures, consistent with reduced turbulent kinetic energy. While …

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 …

Theoretical Model To Predict The Flexural Response Of Concrete Beams Pre-Tensioned With Cfrp Rods Considering Cfrp Slippage Effects, Yasir Saeed, Karrar Al-Lami, Franz Rad

Civil and Environmental Engineering Faculty Publications and Presentations

The overwhelming costs of maintenance for reinforced concrete structures due to steel corrosion have motivated researchers to look for alternatives. One of the promising alternatives is Fiber Reinforced Polymer (FRP). Among FRP materials, Carbon FRP (CFRP) is the most attractive material for prestressed concrete members due to its high tensile strength and modulus of elasticity. Previous studies investigated the use of CFRP in prestressed concrete through experimental tests and theoretical analysis. However, there is a significant need for more experimental data to develop an accurate model that can accurately predict the behavior of CFRP prestressed concrete beams. In the current …

Understanding Structural Risk: Seismic Demand For Low-Fill Slender Fuel Tanks, David Yang, Sam Anderson

Civil and Environmental Engineering Faculty Publications and Presentations

Older fuel storage tanks, such as those in Oregon's CEI Hub, present significant seismic vulnerabilities, prompting proposals to limit storage capacity as a transitional risk mitigation measure before more permanent retrofitting actions. However, a critical knowledge gap exists regarding the applicability of standard analysis methods, like API 650, to low-fill conditions. This study utilizes the Veletsos-Yang iterative fluid-tank interaction procedure to evaluate the seismic demand of low-fill slender tanks. The analysis reveals that low-fill slender tanks exhibit slightly longer impulsive periods compared to fully-filled tanks with identical fill-height to radius ratios. Furthermore, the fixed roof mass of a low-fill tank …

Seasonal Changes In Sediment Sound Speed Profiles, Charles W. Holland, Chad Smith, Tim Sonnemann

Electrical and Computer Engineering Faculty Publications and Presentations

Marine sediment sound speed profiles in the upper ten meters are generally assumed to be constant with time. Models predict that substantive changes occur because of thermal conduction from seasonally varying bottom water temperature. However, definitive measurements have been lacking. In this work, sediment sound speed profiles obtained during different seasons show significant differences in the upper 9 m of mud at the New England Patch. Gradients in late March 2017 are 6.0 s−1 and in early October 2025, 2.6 s−1. This change is shown to have a significant impact on acoustic propagation.

Fuel Tank Seismic Stability Program-Informed Displacement Maps Of Portland's Critical Energy Infrastructure Hub, Ana Tijerina Esquino

Dissertations and Theses

Oregon's Critical Energy Infrastructure (CEI) Hub in northwest Portland contains a large portion of the state's liquid fuel storage and distribution capacity and is located in an area susceptible to liquefaction and earthquake-induced permanent ground deformation during a Cascadia Subduction Zone earthquake. Initial Seismic Vulnerability Assessments submitted under Oregon's Fuel Tank Seismic Stability program provide valuable facility-specific information, but the assessments vary in subsurface characterization, treatment of fine-grained soils, ground motion selection, and deformation estimation methods. This variability complicates interpretation of regional seismic risk and motivates a consistent corridor-scale analysis.

This thesis develops CPT-informed displacement estimates for representative cross sections …

Project Prioritization For Near-Optimal Functionality Risk Reduction In Bridge Networks, David Y. Yang, Anteneh Deriba

Civil and Environmental Engineering Faculty Publications and Presentations

Bridge retrofit prioritization is commonly guided by structural vulnerability, traffic conditions, or indirect consequences following a single bridge failure. However, these metrics often fail to identify retrofit projects that maximally reduce system-level functionality risk, because they do not account for the consequences of joint failures among multiple bridges. This presentation develops a mathematically rigorous, gradient-based approach to bridge retrofit prioritization for achieving a near-optimal reduction in functionality risk. This risk is formulated as the expected increase in total travel time given probabilistic bridge survival or failure under external stressors such as earthquakes. By reinterpreting risk as the evidence term in …

Interpretable Deep Reinforcement Learning For Element-Level Bridge Life-Cycle Optimization, David Y. Yang, Seyyed Amirhossein Moayyedi

Civil and Environmental Engineering Faculty Publications and Presentations

The new Specifications for the National Bridge Inventory (SNBI), in effect from 2022, emphasize the use of element-level condition states (CS) for risk-based bridge management. Instead of a general component rating, element-level condition data use an array of relative CS quantities (i.e., CS proportions) to represent the condition of a bridge. Although this greatly increases the granularity of bridge condition data, it introduces challenges to set up optimal life-cycle policies due to the expanded state space from one single categorical integer to four-dimensional probability arrays. This study proposes a new interpretable reinforcement learning (RL) approach to seek optimal life-cycle policies …

Tidal River Flood Risk Highest During Intermediate Rather Than Peak River Discharge, Leicheng Guo, Adam T. Devlin, Ton Hoitink, Ian Townend, David A. Jay, Zheng Bing Wang, Chunyan Zhu, Hamed R. Moftakhari, Qing He, Fan Xu, Multiple Additional Authors

Civil and Environmental Engineering Faculty Publications and Presentations

Tidal rivers are defined as the tide‐influenced, salinity‐free inland reaches of estuaries. Understanding the occurrence of peak water levels (PWLs) is critical for flood risk management, yet the timing and magnitude of PWLs in tidal rivers have been little studied. We address this gap by investigating PWLs during two catastrophic floods (1954 and 2020) in the tidal Yangtze River, which reveals that PWLs are higher during perigean spring tides under intermediate discharges following peak flow. Three factors modulate the PWLs in tidal rivers: river‐enhanced tidal damping, flow‐elevation hysteresis that raises the falling flow limb of the hydrograph, and low‐frequency subharmonics. …

Investigation Of The Lower Block Rows In The King’S Chamber Of The Great Pyramid Using Ultrasonic Testing With Shear Wave Arrays, Benedikt Maier, Amr G. Hamza, Alejandro Ramirez-Pinero, Khaled Taie, Thomas Schumacher, Olga Popovych, Mohamed Elkarmoty, Mehdi Tayoubi, Hany Helal, Christian U. Grosse

Civil and Environmental Engineering Faculty Publications and Presentations

This study investigates the internal geometry of the granite block rows in the King’s Chamber (KC) of the Great Pyramid of Giza using Non-destructive testing (NDT) with ultrasonic testing (UST) using shear wave echo arrays. As part of the ScanPyramids (SP) project measurement campaigns in 2022, the lower two block rows of all four walls were examined using ultrasonic shear-wave echo arrays (PD8000, Screening Eagle Technologies). The measurement strategy initially included rapid overview acquisitions using an 8-channel UST device to identify potential areas of interest. High-resolution, detailed measurements were then performed at these locations, particularly along the north wall (NW) …

Improved Method Of Evaluating Gas-Phase Air Cleaners Considering Adsorption And Desorption Mechanisms To And From Internal Test Chamber Surfaces, Casey Douglas Coffland

Dissertations and Theses

Portable air cleaners are playing an increasingly important role in managing indoor air quality in response to pressing issues like wildfire smoke events. Smoke is a complex mixture of gases and particulate matter; while established test methods exist for particulate matter, the dynamic behavior of gaseous pollutants is not well accounted for in current test methods. This is because prevailing air cleaner testing methods typically treat background losses as irreversible, whereas gases can engage in partitioning to and from test chamber surfaces. Ignoring these sorption interactions causes inaccurate estimation of an air cleaner's impact.

A new approach has been developed …

Jalzap: An Agile Hybrid For Ai-Accelerated Software Development, Pouya Nouri

University Honors Theses

The rapid adoption of generative AI tools allows software teams to quickly code applications, but it comes at a cost: high scope volatility, technical debt, and unrealistic expectations, which break traditional Agile frameworks. This thesis introduces JALZAP, a lightweight, hybrid Agile framework designed to serve small, high-agility teams facing compressed timelines and unpredictable schedules. This framework was evaluated over 16 weeks through a Portland State University Capstone project working for a pre-seed startup sponsor, where a six-person team built Flowmind: an AI-powered iOS task management app meant to serve users with neurodevelopmental disorders like ADD/ADHD. JALZAP implements structural boundaries, including …

Adaptive Design Strategies For A Dual-Shaft Pvc Shredder, Gavin Balderas

University Honors Theses

This capstone project involved the design and development of a mid-size plastic shredder, created to process strong, ductile PVC sheets up to ½" thick. This application falls between the capabilities of consumer grade plastic shredders and heavy-duty industrial machines. Over 400 million tons of plastic produced annually and less than 10% of it is recycled; there is an ever-growing need for plastic recycling accessibility and infrastructure. This project aimed to create a compact dual-shaft shredder that can shred thick PVC sheets while being powered by a 120V outlet. Research into blade geometry and orientations aided an iterative design process driven …

Universal Communications Module: Converting Ieee2030.5 Xml Files To Ansi/Cta-2045, Wyatt Bilodeaux

University Honors Theses

The goal of this thesis is to discuss the method and organization of the Universal Communication module capstone project. This project was part of the Portland State University Electrical engineering degree program. While this thesis is part of the University honors curriculum. This thesis goes into detail about team structure and how a 9 person engineering capstone project was managed and organized. It looks at how we broke down the project into sections to be able to properly distribute our resources. This was one of the earliest and most important challenges that this capstone team had to tackle. This was …

Rapid-Prototyping Nanofabrication: Lcd-Based Projection Lithography And Physical Vapor Deposition, Sabeel Saleem Mohammmed

University Honors Theses

The semiconductor industry's continued growth, driven in large part by demand for artificial intelligence hardware, has highlighted the need for greater workforce development in regions adjacent to major fabrication centers like Oregon's Silicon Forest. This capstone project lays the groundwork for a small scale and student led semiconductor fabrication lab at Portland State University by demonstrating two of the core steps in chip manufacturing: photolithography and thin film deposition. Rather than relying on conventional fixed reticles, this work explores a unique, low cost approach to patterning that uses an ultraviolet-compatible liquid crystal display (LCD) as a programmable reticle, allowing arbitrary …

Methylglyoxal And Glyoxal In High-Puff Disposable Electronic Cigarette Liquids: Unexpected Accumulation And Enhanced Cytotoxicity, Esther E. Omaiye, Wentai Luo, Kevin J. Mcwhirter, Man Wong, Prue Talbot

Civil and Environmental Engineering Faculty Publications and Presentations

Despite concerns regarding the potential health risks associated with EC use, their design, puff count, and e-liquid formulations have continued to evolve. Aldehydes are a key class of thermal degradation byproducts generated during the vaporization of EC fluids. This study tested the hypothesis that aldehyde concentrations would be elevated in used ECs with high puff numbers. Devices from multiple brands were analyzed to assess the impact of extended use on aldehyde formation. E-fluids were extracted from field-collected and user-donated devices and analyzed using gas chromatography/mass spectrometry to quantify 178 flavor chemicals, two synthetic coolants, nicotine, solvents, and aldehydes (methylglyoxal (MGO), …

Adopting Critical Power Grid Infrastructure Technologies: An Organizational Cybersecurity Assessment Against Ransomware, Fayez Alsoubaie

Dissertations and Theses

For many years, researchers and practitioners have studied emerging technologies in field of energy production and distribution. Power grid systems carry major weights in the energy branch of the economy. Researchers and scientists have been interested in finding ways to connect the power grid gap and improve protection for its technologies.

The research supports organizational adoption and prioritization of critical cybersecurity technologies for ransomware protection in power grid infrastructure. As utilities increasingly integrate digital technologies, they become more vulnerable to sophisticated cyberattacks that can disrupt services and put public safety at risk. The main focus of the study is to …

Foundations' Deep, Emily Williams, Morgan Williams

University Honors Theses

Most historic buildings do not survive as they were built, yet preservation frameworks still tend to evaluate them as if they did.

Foundations' Deep begins with a structure located in Helena, Montana 59602, a building that sits uneasily within the categories it has been asked to meet. Built in the early twentieth century, it has persisted through alteration, abandonment, and use. What remains is not a stable artifact but a record of accumulated decisions, some careful and many indifferent, now embedded in the fabric of the building itself.

The thesis grows from this condition and from the limits of the …

An Exploratory Latent Segmentation Approach To Account For Temporally Shifting Parameters In Driver Injury-Severity Models, Tanmoy Bhowmik, Shahrior Pervaz, Fred Mannering, Naveen Eluru

Civil and Environmental Engineering Faculty Publications and Presentations

Temporally shifting parameters in crash severity modeling is a well-documented phenomenon, with growing evidence suggesting that the influence of explanatory variables changes over time due to shifts in driver behavior, vehicle technology, and roadway conditions. Many studies have examined this issue by comparing the temporal stability of adjacent-year data using a variety of modeling frameworks that have often assumed a homogenous effect of explanatory variables across the entire crash population. The current research effort departs from past work in two ways. First, it compares data separated by multiple years (instead of comparing adjacent years), and second, it tests the homogeneous …