Digital Commons Network^™

Area, Perimeter, Height, And Width Of Rectangle Visibility Graphs, John Caughman, Charles L. Dunn, Joshua Laison, Nancy Ann Neudauer, Colin L. Starr

Mathematics and Statistics Faculty Publications and Presentations

A rectangle visibility graph (RVG) is represented by assigning to each vertex a rectangle in the plane with horizontal and vertical sides in such a way that edges in the graph correspond to unobstructed horizontal and vertical lines of sight between their corresponding rectangles. To discretize, we consider only rectangles whose corners have integer coordinates. For any given RVG, we seek a representation with smallest bounding box as measured by its area, perimeter, height, or width (height is assumed not to exceed width).

Analysis Of Curvature Approximations Via Covariant Curl And Incompatibility For Regge Metrics, Jay Gopalakrishnan, Michael Neunteufel, Joachim Schöberl, Max Wardetzky

Mathematics and Statistics Faculty Publications and Presentations

The metric tensor of a Riemannian manifold can be approximated using Regge finite elements and such approximations can be used to compute approximations to the Gauss curvature and the Levi-Civita connection of the manifold. It is shown that certain Regge approximations yield curvature and connection approximations that converge at a higher rate than previously known. The analysis is based on covariant (distributional) curl and incompatibility operators which can be applied to piecewise smooth matrix fields whose tangential-tangential component is continuous across element interfaces. Using the properties of the canonical interpolant of the Regge space, we obtain superconvergence of approximations of …

Asymmetric Secondary Flows Above Geometrically Symmetric Surface Roughness, Wen Zhang, Xiang Yang, Xiaowei Zhu, Minping Wan, Shiyi Chen

Mechanical and Materials Engineering Faculty Publications and Presentations

The mean flow behaviour of a turbulent boundary layer over rough walls is expected to exhibit symmetries that govern the flow dynamics. In particular, when roughness elements are arranged in a spanwise symmetric manner, the mean flow above them should also exhibit spanwise symmetry. This symmetrical consideration has garnered substantial empirical support. We conduct direct numerical simulations (DNS) of flow over aligned cube arrays to test such symmetry considerations further. We vary the surface coverage density from 0.25 % to 6.25 %, and employ an averaging time of about 100 large-eddy turnover times, which is longer than the typical averaging …

Multi-Agent Deep Reinforcement Learning For Radiation Localization, Benjamin Scott Totten

Dissertations and Theses

For the safety of both equipment and human life, it is important to identify the location of orphaned radioactive material as quickly and accurately as possible. There are many factors that make radiation localization a challenging task, such as low gamma radiation signal strength and the need to search in unknown environments without prior information. The inverse-square relationship between the intensity of radiation and the source location, the probabilistic nature of nuclear decay and gamma ray detection, and the pervasive presence of naturally occurring environmental radiation complicates localization tasks. The presence of obstructions in complex environments can further attenuate the …

Ronald E. Mcnair Scholars Program Profiles And Abstracts 2023, Motutama Sipelii

McNair Symposium

This is the complete event program and provides presentation abstracts and biographies of McNair scholars and their mentors.

Drivers And Dynamics Of Phytoplankton Communities And Harmful Algal Blooms In Mountain Lakes, Lara Stephanie Jansen

Dissertations and Theses

Harmful cyanobacterial blooms (cyanoHABs) are a complex and widespread disturbance in freshwater water bodies, impacting water quality for wildlife and human populations. While cyanobacteria often bloom in warm lakes impacted by human development like agriculture, blooms are increasingly reported in cooler waters with limited development in the surrounding watershed. As much of cyanoHAB research has focused on lakes in highly developed watersheds, the understanding of factors leading to cyanobacteria dominance and blooms in the absence of major development remains limited. Mountain lakes can serve as ideal systems to study bloom-forming cyanobacteria in watersheds with minimal development. In addition, mountain lakes …

Modeling Of Signals And Spectra: 5g And Beyond, Xianzhen Yang

Dissertations and Theses

The collection of papers addresses various aspects of spectra and signals in RF wireless systems for 5G and beyond. The first paper focuses on the nonlinear effects of amplified dual-band OFDM signals, providing a spectrum model for intermodulation and cross-modulation. The second paper extends this analysis beyond bandwidth restrictions, enabling accurate prediction of amplified dual-band spectrum. The third paper emphasizes the significance of out-of-band intermodulation products and derives an analytical expression using third-order intercept points. The fourth paper presents a unified spectrum expression for OFDM, FBMC, and F-OFDM, facilitating comparative insights into these signals. The fifth paper explores second-order intermodulation …

Formalizing Stack Safety As A Security Property, Sean Noble Anderson, Roberto Blanco, Leonidas Lampropoulos, Benjamin C. Pierce, Andrew Tolmach

Computer Science Faculty Publications and Presentations

The term stack safety is used to describe a variety of compiler, runtime, and hardware mechanisms for protecting stack memory. Unlike “the heap,” the ISA-level stack does not correspond to a single high-level language concept: different compilers use it in different ways to support procedural and functional abstraction mechanisms from a wide range of languages. This protean nature makes it difficult to nail down what it means to correctly enforce stack safety.

Water Quality Land Cover Change And Water Quality In Wetlands At The City Of Gresham, Or, Evelyn Barajas, Michael Gonzalez

altREU Projects

The City of Gresham, Oregon has implemented constructed wetlands around the area as an attempt to collect, filter, and purify water from different sources such as rain, agricultural waste, and domestic waste. We focused our research on three different facilities: Columbia Slough Water Quality Facility (CSWQF), Fairview Creek Water Quality Facility, and Brookside Water Quality Facility. For each of these, we conducted tests and looked at the concentration levels for nitrogen and phosphorus nutrients such as NH3-N (ammonium), NO3-N (nitrate), TKN (total Kjeldahl nitrogen), O-PO4 (phosphate), and Total P (total phosphorus), as well as heavy metals like Total Cu (total …

Heat Mapping Crime: A Data-Driven Approach To Policing In New York, Beruktawit Gebreamlak, Daniel Ochoa

altREU Projects

In the aftermath of the COVID-19 pandemic, New York City has seen a surge in criminal activities. In 2023, major crime continues to be higher compared to pre-pandemic levels. Although progress is being made to reduce the number of murders and robberies, law enforcement is continuing to struggle with increases in felony assaults and car thefts. Our project serves to benefit members of the community and law enforcement alike. We created a heat map, which is a visual representation of data that uses colors to represent different values. In the context of crime mapping, our heat map is used to …

A Nested Semiparametric Method For Case-Control Study With Missingness, Ge Zhao, Yanyuan Ma, Jill Schnall Hasler, Scott Damrauer, Michael Levin, Jinbo Chen

Mathematics and Statistics Faculty Publications and Presentations

We propose a nested semiparametric model to analyze a case-control study where genuine case status is missing for some individuals. The concept of a noncase is introduced to allow for the imputation of the missing genuine cases. The odds ratio parameter of the genuine cases compared to controls is of interest. The imputation procedure predicts the probability of being a genuine case compared to a noncase semiparametrically in a dimension reduction fashion. This procedure is flexible, and vastly generalizes the existing methods. We establish the root-n asymptotic normality of the odds ratio parameter estimator. Our method yields stable odds ratio …

A Graph Theory Approach For Public Transit Connectivity In New York City, Francisco Rodriguez, Jhosseline Zhunio

altREU Projects

Transit deserts are defined as not having access to rapid transit, such as train or bus services, within one mile of one’s residence. In New York City, boroughs outside the city’s center struggle with this the most, especially when limited bus services are only offered. Transit deserts bring the most impact for low-income and people of color (POC) communities, limiting their access to essentials such as job opportunities, healthcare, and food supplies. The Metropolitan Transportation Authority (MTA) has tried addressing this issue with experts in arcGIS, a Geographical Information System (GIS) software, resulting in the cutting down of essential bus …

Assessment Of Pathogens In Flood Waters In Coastal Rural Regions: Case Study After Hurricane Michael And Florence, Moiz Usmani, Sital Uprety, Nathan Bonham, Yusuf Jamal, Yuqing Mao, Daisuke Sano, Joanna Shisler, Avinash Unnikrishnan, Thanh H. Nguyen, Antarpreet Jutla

Civil and Environmental Engineering Faculty Publications and Presentations

The severity of hurricanes, and thus the associated impacts, is changing over time. One of the understudied threats from damage caused by hurricanes is the potential for cross-contamination of water bodies with pathogens in coastal agricultural regions. Using microbiological data collected after hurricanes Florence and Michael, this study shows a dichotomy in the presence of pathogens in coastal North Carolina and Florida. Salmonella typhimurium was abundant in water samples collected in the regions dominated by swine farms. A drastic decrease in Enterococcus spp. in Carolinas is indicative of pathogen removal with flooding waters. Except for the abundance presence of Salmonella …

Exploring And Testing Wildfire Risk Decision-Making In The Face Of Deep Uncertainty, Bart R. Johnson, Alan A. Ager, Cody Evers, David Hulse, Max Nielsen-Pincus, John P. Bolte

Environmental Science and Management Faculty Publications and Presentations

We integrated a mechanistic wildfire simulation system with an agent-based landscape change model to investigate the feedbacks among climate change, population growth, development, landowner decision-making, vegetative succession, and wildfire. Our goal was to develop an adaptable simulation platform for anticipating risk-mitigation tradeoffs in a fire-prone wildland– urban interface (WUI) facing conditions outside the bounds of experience. We describe how five social and ecological system (SES) submodels interact over time and space to generate highly variable alternative futures even within the same scenario as stochastic elements in simulated wildfire, succession, and landowner decisions create large sets of unique, path-dependent futures for …

Raps Sheet, Summer 2023, Retirement Association Of Portland State

RAPS Sheet: Monthly Newsletter

No abstract provided.

Modeling And Validating Temporal Rules With Semantic Petri Net For Digital Twins, Han Liu, Xiaoyu Song, Ge Gao, Hehua Zhang, Yu-Shen Liu, Ming Gu

Electrical and Computer Engineering Faculty Publications and Presentations

Semantic rule checking on RDFS/OWL data has been widely used in the construction industry. At present, semantic rule checking is mainly performed on static models. There are still challenges in integrating temporal models and semantic models for combined rule checking. In this paper, Semantic Petri-Net (SPN) is proposed as a novel temporal modeling and validating method, which implements the states and transitions of the Colored Petri-Net directly based on RDFS and SPARQL, and realizes two-way sharing of knowledge between domain semantic webs and temporal models in the runtime. Several cases are provided to demonstrate the possible applications in digital twins …

Evaluating How Well Active Fault Mapping Predicts Earthquake Surface-Rupture Locations, Chelsea Scott, Ramon Arrowsmith, Rachel Adam, Christopher Madugo, Joseph Powell, John Ford, Brian Gray, Ashley Streig, Multiple Additional Authors

Geology Faculty Publications and Presentations

Earthquake surface-fault rupture location uncertainty is a key factor in fault displacement hazard analysis and informs hazard and risk mitigation strategies. Geologists often predict future rupture locations from fault mapping based on the geomorphology interpreted from remote-sensing data sets. However, surface processes can obscure fault location, fault traces may be mapped in error, and a future rupture may not break every fault trace. We assessed how well geomorphology-based fault mapping predicted surface ruptures for seven earthquakes: 1983 M 6.9 Borah Peak, 2004 M 6.0 Parkfield, 2010 M 7.2 El Mayor–Cucapah, 2011 M 6.7 Fukushima-Hamadori, 2014 M 6.0 South Napa, 2016 …

Electrochemical Hydrogen Gas Production And Carbon Dioxide Sequestration Via In Situ Formation Of Nickel (Ii) Tris-(Pyridinethiolate) Derivatives, Dayalis Sv. Brown

Dissertations and Theses

In the research presented, we use electrochemical techniques, such as cyclic voltammetry and controlled potential electrolysis, to study in situ formation of hydrogen evolution catalysts which also reduce carbon dioxide. Using pyridinethiol-based ligands and a nickel (II) precursor, both homo- and heteroleptic complexes were investigated as catalysts to produce alternative fuels while mitigating greenhouse gas emissions. Existing synthetic procedures to obtain these Ni(II) catalysts lead to low yields of the complexes and difficulties in crystallizing samples for further analysis, limiting sample size and restricting the number of studies. While current research is heavily focused on photochemically-driven experiments, given that solar …

Rift-Induced Disruption Of Cratonic Keels Drives Kimberlite Volcanism, Thomas M. Gernon, Stephen M. Jones, Sascha Brune, Thea K. Hincks, Martin Palmer, John C. Schumacher, Rebecca M. Primiceri, Matthew Field, William L. Griffin, Suzanne Y. O'Reilly, Derek Keir, Christopher J. Spencer, Andrew S. Merdith, Anne Glerum

Geology Faculty Publications and Presentations

Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth’s surface in the geologic past^1,2,3. These enigmatic magmas, originating from depths exceeding 150 km in Earth’s mantle¹, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity⁴. Whether their mobilization is driven by mantle plumes⁵ or by mechanical weakening of cratonic lithosphere^4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical …

The Impact Of Climate Change On Selected Pnw Watersheds Through The Lens Of Western Red Cedar Habitat, Jordan T. Hamann

Dissertations and Theses

Climate change is a real phenomenon that is exacerbating existing natural processes and developing into a new normal for the planet. This change may be devastating for Pacific Northwest populations of Western Red Cedar (WRC) west of the Cascade Mountain range in the states of Oregon and Washington. WRC is a valuable tree species for reasons both economic and cultural. Dieback among WRC is following an accelerating trend. Since dieback is usually followed by tree mortality, understanding its causes and distribution is beneficial to the overall success of the species going into the future.

Through the use of ESRI's ArcGIS …

Confronting Web3 Technology: Opportunities, Challenges And Community Formation, Christopher-John Rogers

Dissertations and Theses

The emergence of blockchain technology created an entire industry of innovative new digital assets--or tokens--and diverse new fields of expertise founded on ideological aspirations of a new World Wide Web that reimagines digital value transfer through decentralization and disintermediation. Experimentation in the so-called "Web3" industry produces rich new fields of ethnographic study revealing the experiences of diverse individuals navigating novel technological capabilities which give way to new avenues of identity formation, community building, and ecosystem creation. These exciting new endeavors come with difficult challenges threatening the realization of ambitious visions for digital futures. Ethnographic research conducted through discourse analysis, participant …

Collaborative Action In Informal Social Networks Of Wildfire Managers In Northwestern Wyoming, Hannah Lynn Spencer

Dissertations and Theses

Wildfire is a cross-boundary, collective action issue. Previous research has demonstrated the importance of collaborative relationships in wildfire for purposes such as increasing capacity, trading information, and facilitating landscape-scale mitigation projects. However, a stakeholder's location in social networks, as well as personal factors, may impact their collaboration. Furthermore, stakeholders must prioritize their own organizational goals and responsibilities, which may differ from those of their collaborators. I used interview and survey methods to investigate these questions in the context of wildfire management professionals in northwestern Wyoming. For the interviews, I selected 12 individuals with high betweenness centrality who were involved in …

Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen

Dissertations and Theses

Volcanic glass has been used extensively as a paleoclimate proxy. Deuterium (²H) concentrations in glass have been found to be stable over geologic timescales, making δD a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in ash. Here, I analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ashflow tuff, and create an isoscape to assess variations in δD across Oregon during that time. Additionally, I examine compositional data from glass shards to explore the relationship between δD and shard composition. The RST exhibits …

Disentangling Groundwater Dynamics At Oregon's Mckenzie River Headwaters, Taylor Nicole Salazar

Dissertations and Theses

Widespread mountain snowpack declines have been occurring across the western United States over the last century, and are increasing in duration and severity, with several record-breaking low-snowpack years in the last decade. In the Pacific Northwest, summer streamflow is largely a result of melting snow and groundwater discharge, as summers are typically dry and warm in this Mediterranean bioclimate, thus making spring-fed rivers critical for regional water resources. However, current trends and predictions in hydroclimate modeling indicate spring-fed rivers will experience reduced summer discharge driven by the increasingly larger impact of anthropogenic climate change (warming) on (decreased) mountain snowpack. A …

Systematic Characterization Of Power Side Channel Attacks For Residual And Added Vulnerabilities, Aurelien Tchoupou Mozipo

Dissertations and Theses

Power Side Channel Attacks have continued to be a major threat to cryptographic devices. Hence, it will be useful for designers of cryptographic systems to systematically identify which type of power Side Channel Attacks their designs remain vulnerable to after implementation. It’s also useful to determine which additional vulnerabilities they have exposed their devices to, after the implementation of a countermeasure or a feature. The goal of this research is to develop a characterization of power side channel attacks on different encryption algorithms' implementations to create metrics and methods to evaluate their residual vulnerabilities and added vulnerabilities. This research studies …

In Their Words: Prospective Teachers' Experiences As A Context For Investigating Their Views Of Authority In A Mathematics Classroom, Brenda Lynn Rosencrans

Dissertations and Theses

Mathematics teacher educators enact inquiry-based preparatory courses with the underlying expectation that their students (prospective teachers) will take ownership (authority) of their mathematical learning through sharing their ideas and collaboratively discussing the reasonableness of their shared ideas. Yet, prospective teachers' expectations are often not yet in alignment with those of mathematics teacher educators, instead they enter these courses expecting their instructors to provide clear examples and directions for how to solve mathematics problems. This project investigates this dynamic through an authority lens, seeking to understand and characterize different views of authority prospective teachers hold and the impact these views have …

Quantifying Uncertainties In Direct-Numerical-Simulation Statistics Due To Wall-Normal Numerics And Grids, Peng E. S. Chen, Xiaowei Zhu, Yipeng Shi, Xiang I. A. Yang

Mechanical and Materials Engineering Faculty Publications and Presentations

This paper takes the perspective of a user of direct-numerical-simulation (DNS) data and quantifies the uncertainties in DNS statistics for plane channel flows. We focus on high-order statistics, such as skewness, kurtosis, and viscous dissipation, and quantify the uncertainties due to wall-normal numerics and grids while minimizing the sampling error and the discretization error in the wall-parallel directions. Two grid distributions and four discretization methods are considered, which are representative of the existing DNSs. Our results show that the available DNS data contain at least a 7% uncertainty in the computed mean viscous dissipation in the buffer layer. Moreover, since …

Distributed Deep Learning Optimization Of Heat Equation Inverse Problem Solvers, Zhuowei Wang, Le Yang, Haoran Lin, Genping Zhao, Zixuan Liu, Xiaoyu Song

Electrical and Computer Engineering Faculty Publications and Presentations

The inversion problem of partial differential equation plays a crucial role in cyber-physical systems applications. This paper presents a novel deep learning optimization approach to constructing a solver of heat equation inversion. To improve the computational efficiency in large-scale industrial applications, data and model parallelisms are incorporated on a platform of multiple GPUs. The advanced Ring-AllReduce architecture is harnessed to achieve an acceleration ratio of 3.46. Then a new multi-GPUs distributed optimization method GradReduce is proposed based on Ring-AllReduce architecture. This method optimizes the original data communication mechanism based on mechanical time and frequency by introducing the gradient transmission scheme …

Modeling Cyanotoxin Production, Fate, And Transport In Surface Water Bodies Using Ce-Qual-W2, Bernadel Rose Hintz Garstecki, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

Cyanobacteria are frequently associated with forming toxic blooms. The toxins produced by cyanobacteria, cyanotoxins, are harmful to both humans and animals. Rising temperatures due to global climate change are expected to increase the occurrence of cyanobacteria, and it is vital that we protect our drinking water supplies and natural water resources. Modeling the production, fate, and transport of these toxins is an important step in limiting exposure to them and evaluating management strategies to mitigate their impact. The research provided here offers an overview of some of the main cyanotoxins of concern and presents preliminary models for the transport and …

Current Vehicle Fleet Inventory And Future Implementation Of A Centralized Electric Fleet At Portland State University, Dane Kovaleski

Environmental Science and Management Professional Master's Project Reports

As the effects of climate change continue to impact the world, many institutions have developed climate action goals to reduce their effects on the environment. Portland State University (PSU) has committed to an 80% reduction of greenhouse gas emissions by 2030 and carbon neutrality by 2040. A part of this commitment must include looking at the contributions of transportation on campus to reduce carbon emissions. According to a greenhouse gas emissions report done by the Campus Planning and Sustainability Office in 2016, transportation contributed to 12% of total greenhouse gas emissions on campus.

This project aims to evaluate the management …