Digital Commons Network^™

A Projector-Rank Partition Theorem For Exact Degrees Of Freedom In Experimental Design, K. G. Nagananda

Mathematics and Statistics Faculty Publications and Presentations

In many experimental designs—split-plots, blocked or nested layouts, fractional factorials, and studies with missing or unequal replication—standard ANOVA procedures no longer tell us exactly how many independent pieces of information each effect truly contributes. We provide a general degrees of freedom (df) partition theorem that resolves this ambiguity. For N observations, we show that the total information in the data (i.e., N −1 df) can be split exactly across experimental effects and randomization strata by projecting the data onto each stratum and counting the df each effect contributes there. This yields integer df—not approximations—for any mix of fixed and random …

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 …

Factors Influencing Enterprise Adoption Of Ai-Enabled Computers: An Expert Judgment Quantification Approach Across Multiple Sectors, Yu Shan Su, Tugrul Daim, Chia-Hao Hung, Leong Chan, Dana Bakry

Engineering and Technology Management Faculty Publications and Presentations

This study examines the key factors influencing the adoption of Artificial Intelligence Personal Computers (AIPCs) by enterprises, exploring both the benefits and challenges of their business applications. As enterprises increasingly require real-time computing, autonomous decision-making, and improved cybersecurity, AIPC—combining artificial intelligence and edge computing—has become a strategic technology for boosting competitiveness. Particularly in scenarios with less reliance on cloud services, businesses are more likely to adopt devices with local processing and standalone AI capabilities to meet the dual needs of operational efficiency and data privacy. Through an extensive review of the literature, this study identifies four main dimensions and sixteen …

Not Merely A Workaround: Theorizing Asynchronous Math Talks As A Robust Instructional Routine For Visible Thinking, Participation, And Engagement In Mathematics Teacher Education, Simon Byeonguk Han

Dissertations and Theses

The sudden global shift due to COVID-19 accelerated the need for a better understanding of mathematics learning and teaching in an asynchronous format. Also, despite the popular use of mathematics instructional routines in mathematics classrooms, the field of mathematics education research has very limited empirical studies on instructional routines. This dissertation addresses this by examining Asynchronous Math Talks (AMTs), a structured instructional routine adapted from Number Talks. The central goal of this research is to develop and theorize AMTs not merely as an online workaround, but as a robust instructional model that leverages the unique affordances of digital platforms to …

Factors Influencing Non-Perennial Stream Initiation In The Mt. Hood National Forest, Allison Bast

Dissertations and Theses

Historically, non-perennial headwater streams have been overlooked due to their small size and infrequent flow regimes, often leading to them not being recognized as legitimate streams, despite scientific evidence that has shown these streams significantly affect the quality of downstream waters. To combat this issue, environmental managers need to be able to accurately identify and delineate the origins of these streams; however, despite decades of research, an accurate, universal method for predicting how and where these streams commence has yet to be developed. Early studies conducted in steep, humid environments, identified a strong inverse linear relationship between the size of …

Epidemic Dynamics Under Pulse Population Exchange, Hannah Kravitz, Christina Durón, Moysey Brio

Mathematics and Statistics Faculty Publications and Presentations

Many epidemiological models assume either closed populations or continuous demographic turnover. We consider an intermediate setting in which exchange occurs through discrete pulses. In this paper, we introduce a population-conserving compartmental epidemiological model with pulse population exchange at a set of prescribed times. At each pulse, a fraction of the population in each compartment is replaced by a combination of susceptible and immunized individuals. In contrast to typical pulse birth or pulse vaccination models where only a single compartment undergoes a pulse population change, the pulses in this model have competing effects: removing infectious individuals reduces the force of infection, …

A Systematic Approach For Controlling Tem Sample Thicknesses, Monte Kozell

Physics Faculty Publications and Presentations

Historically, TEM prep has been an artisan craft without a systematic workflow that ensures quantified control over TEM sample thickness. Over- and under-thinning is a significant problem in the TEM prep process. A direct measurement process was demonstrated to control the final thickness of the TEM lamella. Final lamella thickness was controlled by directly measuring lamella thickness in real time using a 10–15 kV SEM while performing secondary electron imaging at the mill position, allowing for (human-mediated) closed-loop processing. We demonstrated the utility of this technique by systematically thinning five TEM samples to discretely target thicknesses ranging from 100 nm …

Multi-Solution Ternary Grover’S Algorithm For Logic-Based Quantum Machine Learning With Pseudo-Kronecker Reed–Muller Form Minimization, Sophia Lee, Ali Al-Bayaty, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

Optimization problems in machine-learning (ML) applications can be computationally challenging for classical methods, particularly when they involve large, unstructured search spaces. Quantum computing offers a promising approach to combinatorial optimization by utilizing quantum superposition and amplitude amplification. This paper presents a new methodology using logic-based quantum machine learning (QML) as a complete framework for employing a multi-solution ternary Grover’s algorithm to minimize incomplete binary functions represented by Pseudo-Kronecker Reed–Muller (PKRO) expansions, consistent with Occam’s razor principle. Unlike previous quantum approaches based on Kronecker Reed–Muller (KRO) or fixed-polarity Reed–Muller (FPRM) representations, our work introduces the first Grover-based optimization framework for PKRO …

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, …

Extending W-Event Differential Privacy To The Publish-Subscribe Framework, Jacob Jerome Olinger

Dissertations and Theses

Internet of Things (IoT) devices have become ubiquitous, permeating both enterprises and homes, and they increasingly rely on publish-subscribe (pub-sub) frameworks that give subscribers real-time, high-fidelity access to device data. For privacy and confidentiality, however, today's pub-sub systems largely stop at channel-level authentication, encryption, and access-control lists. These protect data in transit and restrict who may receive it, but place no quantitative limit on what a subscriber with legitimate access to messages can infer about its publishers.

We close this gap by extending w-event differential privacy to the pub-sub setting. We generalize it from count queries to any aggregate …

Inherited Local Shrinkage For Adaptive Functional Form Discovery, Jacob Colestin Schultz

Dissertations and Theses

Statistical models frequently employ nonlinear effects, interactions, and multiresolution basis expansions to represent complex relationships between predictors and responses. Determining the appropriate level of model complexity, however, remains a fundamental challenge. This dissertation introduces Inherited Local Shrinkage (ILS), a Bayesian global-local shrinkage framework for adaptive functional form discovery that enforces strong heredity among hierarchically related predictors.

ILS propagates shrinkage through directed acyclic graphs representing predictor inheritance, ensuring that increasingly complex terms are retained only when supported by simpler parent structure. The framework applies broadly to polynomial regression, interaction models, wavelets, splines, and other hierarchical basis expansions, while naturally extending to …

Representing Post-Fire Reality: An Empirically Informed Temperature Index Approach To Post-Fire Hydrologic Modeling In Oregon's Western Cascades, Logan Hastings

Dissertations and Theses

The invaluable water resources stored in snowpack face mounting threats from rising temperatures, drought, shifts in precipitation regimes, and increased fire frequency, which pose challenges to operational hydrologic modeling in Oregon's sensitive maritime snowpacks. The gridded temperature index (GTI) approach in operational models like the Hydrological Engineering Center's Hydrologic Modeling System (HEC-HMS) from the U.S. Army Corps of Engineers remains in common use for its minimal data requirements, but how GTI parameterizations should adapt to post-fire conditions is largely unknown.

This research assessed the impact of the 2020 Lionshead Fire on HEC-HMS performance in the North Santiam River basin across …

Evolution Of Global Sea‐Level Rise Projections And Their Uncertainty, Andra J. Garner, Amy Appollina, Jessica Slotter, Gregory G. Garner, Aimée B. A. Slangen, Robert E. Kopp, Benjamin P. Horton

School of Earth, Environment, and Society Faculty Publications and Presentations

For more than 40 years, scientists have projected future sea‐level change. Documenting how sea‐level projections have evolved is vital for tracking progress, uncertainties, and future research needs. Here, we update and analyze a database of global‐mean sea level (GMSL) projections dating from 1982 to 2025, identifying five key findings. First, GMSL projection generation has been concentrated in a small number of developed countries, with 95% of projections produced in the United States, United Kingdom, European Union, or Australia. Second, while GMSL projections for 2050 and 2100 have been published regularly since the early 1980s, only 30 of 103 studies have …

Oregon State Rank Assessment For Schweinitz's Cyperus (Cyperus Schweinitzii), Nora Dunkirk

Institute for Natural Resources Publications

Oregon state conservation status assessment for Schweinitz's cyperus (Cyperus schweinitzii) using NatureServe methodology, 2026.

Credence Goods In Markets With Collective Reputation: Nature Of Equilibria And The Value Of Certification, Erin Krupka, Thomas P. Lyon, Arnab Mitra

Economics Faculty Publications and Presentations

Fraud can cause markets for credence goods to collapse, but collective reputation has been suggested as a potential solution, especially when buyer valuations for quality are high. We develop a discrete model of a market for label credence goods and provide conditions for no-fraud equilibria based on collective reputation. We identify conditions under which all equilibria may be asymmetric or involve mixed strategies and hence sellers may face coordination problems. Our analysis suggests such coordination problems are the greatest when the size of the high-quality market is approximately half of the overall market (that incorporates both high- and low-quality goods), …

Statistical Model Of Subsurface Scattering Bias In Icesat‐2'S Atl06 Product, Thilini Bamunu Arachchige, Kelly E. Gleason, Jonathan C. Ryan, Markus Allgaier

Environmental Science and Management Faculty Publications and Presentations

ICESat‐2 uses visible laser pulses and photon‐counting detectors to range the Earth's surface, providing precision altimetry for measuring ice sheet elevation change. However, since water ice is transparent to visible light, the photon returns recorded by ICESat‐2's ATLAS instrument may originate from subsurface scattering inside the snow or glacier ice volume, making the surface appear lower than it is. Here, we develop a Monte Carlo Radiative Transfer model to characterize the potential bias caused by subsurface scattering in snow and ice. Our model allows us to study the subsurface scattering bias in relation to photon number, scattering coefficient, and slope …

Oregon State Rank Assessment For Koehler's Rockcress (Boechera Koehleri), Lindsey K. Wise, Gabriel Campbell

Institute for Natural Resources Publications

Oregon state conservation status assessment for Koehler's rockcress (Boechera koehleri) using NatureServe methodology, 2026.

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 …

Feedback Indices To Evaluate Llm Responses To Rebuttals For Multiple Choice Type Questions, Justin C. Dunlap, Anne-Simone Parent, Ralf Widenhorn

Physics Faculty Publications and Presentations

We present a set of indices designed to characterize Large Language Model (LLM) responses when challenged with rebuttals during a chat. Assessing how LLMs respond to user dissent is crucial for understanding their reliability and behavior patterns, yet the complexity of human-LLM interactions makes systematic evaluation challenging. Our approach employs a fictitious-response rebuttal method that quantifies LLM behavior when presented with multiple-choice questions followed by deliberate challenges to their fictitious previous response. The indices are specifically designed to detect and measure what could be characterized as sycophantic behavior (excessive agreement with user challenges) or stubborn responses (rigid adherence to the …

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 …

Oregon State Rank Assessment For Stemmed Polypore (Xeroceps Skamania), Nora Dunkirk

Institute for Natural Resources Publications

Oregon state conservation status assessment for Stemmed Polypore (Xeroceps skamania) using NatureServe methodology, 2026.

Surface Co-Crystallization With An Organic Single Crystal Enables Vapochromic And Luminescent Detection Of Phenols., Ivan Bondarenko, Kaleb Hood, Elani J. Cabrera-Vega, Aminata Dioume, Alaric Shaw, Josephine Bicknell, Simon J. Teat, Nicholas S. Settineri, Andrea M. Goforth, Stephanie S. Lee, Jun Jiao, Gonzalo Campillo-Alvarado

Chemistry Faculty Publications and Presentations

We present a novel approach for the vapochromic and luminescent detection of phenols through surface co-crystallization with single crystals of 9,10-bis(()-2-(pyridin-4-yl)vinyl)anthracene BP4VA. Upon exposure to 2,4,6-trifluorophenol (2,4,6-TFP), 3,4,5-trifluorophenol (3,4,5-TFP), and phenol (PhOH) vapor, BP4VA crystals exhibit significant changes in color and fluorescence intensity, offering a sensitive detection method. Detailed structural insights into intermolecular interactions are obtained from single-crystal and powder X-ray diffraction, as well as FT-IR and H NMR spectroscopies. Scanning electron microscopy and energy dispersive X-ray spectroscopy demonstrate the reversibility of these changes, with crystal morphology and surface composition nearly returning to near-pristine single crystals of BP4VA after annealing. …

Temperature And Hydrologic Context Influence Methane Variability In A Low-Salinity Marsh, Zoie Brauser

Dissertations and Theses

Coastal wetlands are biogeochemical hotspots that capture and transform carbon and nutrients. Wetland restoration is increasingly used as a climate mitigation strategy because of wetlands' capacity to sequester large amounts of carbon. However, low-salinity tidal marshes exhibit high variability in methane (CH₄) emissions, which could partially offset carbon sequestration under certain conditions. Understanding the drivers of CH₄ variability is crucial for restoration and conservation work. This project uses an observational research approach to assess the relationships between environmental factors and carbon dioxide (CO₂) and CH₄ soil gas fluxes in a restored low-salinity tidal marsh …

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 …

Set-Valued Conjugate Calculus And Duality In Optimization And Machine Learning Via Generalized Relative Interiors, Gary Lee Sandine

Dissertations and Theses

Convex analysis, optimization, and duality theory are broadly applicable to a multitude of real-world problems. Theoretical frameworks ensuring strong duality and optimality are fundamentally tied to convex separation under qualification conditions frequently involving topological or relative interiors. These can be empty in convex sets that appear naturally in infinite-dimensional models, yet guarantees of optimality and strong duality are often attainable. This dissertation presents frameworks for applying convex separation via generalized relative interiors to develop generalized calculus rules as well as conditions for strong duality and optimality for infinite-dimensional constrained convex optimization problems.

The first major contribution is the introduction of …

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 …

Experiences Of Psychological Recovery From Work In Second-Generation Asian Americans, Laura Yang

Dissertations and Theses

Individuals of Asian descent make up approximately 7.4% of the U.S. population. As one of the fastest-growing minority groups, their population is projected to reach nearly 15% by 2065, with 38% being foreign-born – surpassing all other racial minority groups. Despite their increasing presence in the U.S. workforce, research on Asian workers' nonwork experiences remains limited. One key unexplored area is how Asian workers engage in recovery after work, considering their unique cultural and racialized experiences. Drawing on literature examining psychological recovery from work, this qualitative study employed multiple methods of analysis, both listening guide method and thematic analysis, to …

Oregon State Rank Assessment For Deer-Cabbage (Nephrophyllidium Crista-Galli), Lindsey K. Wise

Institute for Natural Resources Publications

Oregon state conservation status assessment for Deer-cabbage (Nephrophyllidium crista-galli) using NatureServe methodology, 2026.

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 …

Moss Biomonitoring And Isotopic Signatures Reveal Aviation Fuel As Local Lead Source Near Oregon Airports, Oluwaseyi E. Aderinboye, Alyssa E. Shiel, Lauren Stalford, Christina J. Murphy, Dean B. Atkinson

Chemistry Faculty Publications and Presentations

Lead emissions from piston-engine aircraft using leaded aviation gasoline (avgas) remain a significant source of environmental contamination near regional airports, posing potential health risks to nearby communities. Passive biomonitoring using the epiphytic moss Orthotrichum lyellii was combined with lead isotope fingerprinting to quantify lead concentrations and distinguish between legacy leaded gasoline and current avgas emissions near Hillsboro and Troutdale airports in Oregon. Here we show that lead levels are elevated by up to 50 times the rural background near airports, with isotopic signatures confirming avgas as a dominant local source. These findings indicate that avgas use contributes substantially to environmental …