Digital Commons Network^™

Analyzing Network Topology For Ddos Mitigation Using The Abelian Sandpile Model, Bhavana Panchumarthi, Monroe Ame Stephenson

altREU Projects

A Distributed Denial of Service (DDoS) is a cyber attack, which is capable of triggering a cascading failure in the victim network. While DDoS attacks come in different forms, their general goal is to make a network's service unavailable to its users. A common, but risky, countermeasure is to blackhole or null route the source, or the attacked destination. When a server becomes a blackhole, or referred to as the sink in the paper, the data that is assigned to it "disappears" or gets deleted. Our research shows how mathematical modeling can propose an alternative blackholing strategy that could improve …

A New Look At The Quantum Liouville Theorem, P. T. Leung, G. I. Ni

Physics Faculty Publications and Presentations

We clarify certain confusions in the literature of the density operator in quantum mechanics, and demonstrate that the quantum Liouville theorem has the same form in both the Schrodinger and the Heisenberg pictures. Our starting point is to treat the density operator as an observable which has its specific time dependence in each of the two pictures. It is further shown that such a formulation will provide the exact correspondence between classical and quantum statistical mechanics with the Liouville theorem being interpreted as a conservation law, which is derivable from the equation of motion only in the quantum case.

Eagle Creek Post-Fire Monitoring For Water Temperature & Water Stage, Sylas Daughtrey

Environmental Science and Management Professional Master's Project Reports

When investigating forested watersheds devastated by wildfire, the wide range of disturbance can lead to altering hydrological effects through the loss in ground cover vegetation, canopy cover, while also disrupting soil characteristics. Within the Pacific Northwest, forested drainages affected by post-fire disturbance are further altered in areas that experience seasonal rainfall and snow melt events. When looking at the post-fire sloped areas of Eagle Creek and Tanner Creek within the Columbia Gorge of Oregon, the loss of ground cover and organic matter throughout these two watersheds pose a legitimate concern for erosion events as well as hydrological changes due to …

A Unified Spectrum Formulation For Ofdm, Fbmc, And F-Ofdm, Xianzhen Yang, Siyuan Yan, Xiao Li, Fu Li

Electrical and Computer Engineering Faculty Publications and Presentations

Although orthogonal frequency division multiplexing (OFDM) has been standardized for 5G, filter bank multi-carrier (FBMC) and filtered orthogonal frequency division multiplexing (F-OFDM) remain competitive as candidates for future generations of wireless technologies beyond 5G, due to their reduced spectrum leakage and thus enhanced spectrum efficiency. In this article, we developed a unified spectrum expression for OFDM, FBMC, and F-OFDM, which provides comparative insights into those techniques. A representative sideband quantification is included at the end of this article.

Connexin-46/50 In A Dynamic Lipid Environment Resolved By Cryoem At 1.9 Å, Jonathan A. Flores, Bassam G. Haddad, Kimberly A. Dolan, Janette Bernadette Myers, Craig C. Yoshioka, Jeremy Yoshioka, Daniel M. Zuckerman, Steve L. Reichow

Chemistry Faculty Publications and Presentations

Gap junctions establish direct pathways for cells to transfer metabolic and electrical messages. The local lipid environment is known to affect the structure, stability and intercellular channel activity of gap junctions; however, the molecular basis for these effects remains unknown. Here, we incorporate native connexin-46/50 (Cx46/50) intercellular channels into a dual lipid nanodisc system, mimicking a native cell-to-cell junction. Structural characterization by CryoEM reveals a lipid-induced stabilization to the channel, resulting in a 3D reconstruction at 1.9 Å resolution. Together with all-atom molecular dynamics simulations, it is shown that Cx46/50 in turn imparts long-range stabilization to the dynamic local lipid …

A Simple Predictive Model For Estimating Relative E-Cigarette Toxic Carbonyl Levels, Shawna Vreeke, Xijing Zhu, Robert Strongin

Chemistry Faculty Publications and Presentations

E-cigarette devices are wide ranging, leading to significant differences in levels of toxic carbonyls in their respective aerosols. Power can be a useful method in predicting relative toxin concentrations within the same device, but does not correlate well to inter-device levels. Herein, we have developed a simple mathematical model utilizing parameters of an e-cigarette’s coil and wick in order to predict relative levels of e-liquid solvent degradation. Model 1, which is coil length/(wick surface area*wraps), performed in the moderate-to-substantial range as a predictive tool (R² = 0.69). Twelve devices, spanning a range of coil and wick styles, were analyzed. …

The Scicommdiversity Travel Fellowship: The Challenge Of Creating A Sustainable Intervention, Alberto I. Roca, Cynthia-Lou Coleman, Tara S. Haelle, Danielle N. Lee

Communication Faculty Publications and Presentations

Diversifying a community requires outreach, recruitment, and retention which in this case targets the science communication (SciComm) workforce. Establishing a strategy to accomplish such diversification includes designing, launching, and sustaining the new intervention. Here we review the 6-years history of the DiverseScholar SciCommDiversity Travel Fellowship. This intervention was designed to build a community of minority science communicators that would interact with experienced professionals at the ScienceWriters conference. The travel fellowship reduces the financial burden of conference attendance while introducing the fellows to mentors who facilitate networking and knowledge-building during the event’s professional development opportunities. The first two years of the …

Lectures On Mathematical Computing With Python, Jay Gopalakrishnan

PDXOpen: Open Educational Resources

This open resource is a collection of class activities for use in undergraduate courses aimed at teaching mathematical computing, and computational thinking in general, using the python programming language. It was developed for a second-year course (MTH 271) revamped for a new undergraduate program in data science at Portland State University. The activities are designed to guide students' use of python modules effectively for scientific computation, data analysis, and visualization.

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Joint Lattice Of Reconstructability Analysis And Bayesian Network General Graphs, Marcus Harris, Martin Zwick

Complex Systems Faculty Publications and Presentations

This paper integrates the structures considered in Reconstructability Analysis (RA) and those considered in Bayesian Networks (BN) into a joint lattice of probabilistic graphical models. This integration and associated lattice visualizations are done in this paper for four variables, but the approach can easily be expanded to more variables. The work builds on the RA work of Klir (1985), Krippendorff (1986), and Zwick (2001), and the BN work of Pearl (1985, 1987, 1988, 2000), Verma (1990), Heckerman (1994), Chickering (1995), Andersson (1997), and others. The RA four variable lattice and the BN four variable lattice partially overlap: there are ten …

Reconstructability Analysis And Its Occam Implementation, Martin Zwick

Complex Systems Faculty Publications and Presentations

This talk will describe Reconstructability Analysis (RA), a probabilistic graphical modeling methodology deriving from the 1960s work of Ross Ashby and developed in the systems community in the 1980s and afterwards. RA, based on information theory and graph theory, resembles and partially overlaps Bayesian networks (BN) and log-linear techniques, but also has some unique capabilities. (A paper explaining the relationship between RA and BN will be given in this special session.) RA is designed for exploratory modeling although it can also be used for confirmatory hypothesis testing. In RA modeling, one either predicts some DV from a set of IVs …

Hypergraph Analysis Of Structure Models, Cliff A. Joslyn, Teresa D. Schmidt, Martin Zwick

Complex Systems Faculty Publications and Presentations

Theoretical discussion on the analysis of hypergraph networks; application of analysis methods to hypergraph networks derived by applying Reconstructability Analysis to health care data (the PhD dissertation work of Teresa Schmidt).

Variability In Historical Fire Patterns Of A Moist Mixed-Conifer Forest In The Northern Blue Mountains Of Oregon, Laura Marie Platt

Dissertations and Theses

High variability in historical fire patterns characteristic to mixed-severity fire regimes is expected to have contributed to a structurally heterogeneous landscape throughout much of the forested ecosystems of the western United States. After more than a hundred years of fire exclusion in the region, many forests have shifted to a more homogeneous structure, which raises concern regarding these forests' ability to sustain expected increases in fire activity with a warming climate. The shift is not uniform across the west, however, and differences in historical disturbance patterns and changes due to land management are not well characterized in forests across a …

Statistical Modeling Of Historical Daily Water Temperatures In The Lower Columbia River, Malia Hanae Scott

Dissertations and Theses

Water temperature affects numerous aspects of aquatic life, and its stability is critical to cold water fish such as salmonids. With rising anthropogenic influence in natural environments, the future existence of these organisms is becoming less certain. In this study, I examined the evolution of historical water temperatures in the lower Columbia River by creating a statistical model to estimate daily historical water temperatures between the 1850s and 2010s. Daily air temperature and river flow measurements were used as inputs to the model, which estimated daily water temperatures at Bonneville Dam. The model used time lags between air temperature and …

A Computer Science Academic Vocabulary List, David Roesler

Dissertations and Theses

This thesis documents the development of the Computer Science Academic Vocabulary List (CSAVL), a pedagogical tool intended for use by English-for-specific-purpose educators and material developers. A 3.5-million-word corpus of academic computer science textbooks and journal articles was developed in order to produce the CSAVL. This study draws on the improved methodologies used in the creation of recent lemma-based word lists such as the Academic Vocabulary List (AVL) and the Medical Academic Vocabulary List (MAVL), which take into account the discipline-specific meanings of academic vocabulary. The CSAVL provides specific information for each entry, including part of speech and CS-specific meanings in …

Guided Reinvention As A Context For Investigating Students' Thinking About Mathematical Language And For Supporting Students In Gaining Fluency, Kristen Vroom

Dissertations and Theses

Fluency with mathematical language is important for students' engagement in many disciplinary practices such as defining, conjecturing, and proving; yet, there is growing evidence that mathematical language is challenging for undergraduate students. This dissertation study draws on two design experiments with pairs of students who were supported to encode their mathematical meanings with more formal language. I aimed to investigate the teaching and learning of mathematical language, and particularly the language in statements with multiple quantifiers, by engaging students in this type of activity. In the first paper, I investigated the complex ways in which the students in my study …

Short- And Long-Term Impacts Of A Deliberative Pedagogy In Introductory Biology And Chemistry Courses, Liz Rain-Griffith

Dissertations and Theses

There have been multiple national calls for curricular reform in college-level science, technology, engineering, and mathematics (STEM), including a need to instill democratic skills in students. Democratic skill building can be embedded in STEM classrooms through intentional "deliberative pedagogies" which include skills in: communication, collaboration, and application. We developed and implemented a deliberative pedagogy, Deliberative Democracy (DD), across introductory majors and non-majors biology courses and a majors chemistry course. In two separate studies, I took a longitudinal, qualitative research approach to understand introductory biology and chemistry students' experiences and perceptions of DD. For the first study, I tracked a cohort …

Mechanics Of Canopy Turbulence, Hawwa Falih Kadum

Dissertations and Theses

Large canopies interact with the atmospheric boundary layer (ABL) and alter transport of matter, energy, and momentum in accordance to their morphology. Canopy structure influence on turbulent processes can be utilized to achieve favorable interactions. Wind farm and forest canopies spatial arrangement is investigated in this work. Momentum fluxes investigated in a horizontal axis wind turbine (HAWT) array showed the existence of gusts of wind transported both from ABL above the canopy and the unperturbed flow below the canopy through sweep and ejection events. A new wind farm arrangement in which clusters of vertical axis wind turbines (VAWT) are collocated …

Exploring The Factors Influencing Big Data Technology Acceptance, Mohammad Nayemur Rahman

Dissertations and Theses

The success of new technology depends on user acceptance. Therefore, discovering the antecedents of technology use is pivotal to overcoming the lack of user acceptance in the field of technology adoption. Factors of critical technological capability, in particular, are overlooked and largely neglected in the literature. Accordingly, the body of literature on the field of technology adoption is inconclusive as to which technological capability factors influence technology acceptance.

Big Data has received great attention in academic literature and industry papers. Most of the experiments and studies focused on publishing results of big data technologies development, machine learning algorithms, and data …

Understanding Institutional, Social, And Ecological Systems Influencing Climate Change Adaptation And Water Governance In Wine Regions: A Comparative Case Study Of Oregon's Willamette Valley, Usa And Tasmania, Australia, Erin Upton

Dissertations and Theses

My research examines how water management decisions create opportunities or barriers to climate change adaptation in wine regions. Water is a critical resource for economic and environmental sustainability in wine grape growing regions. Climate uncertainty presents considerable risk and vulnerability to freshwater resources in wine producing regions where needs for access to water will increase with more frequent climate extremes. Climate adaptation in the wine industry is a complex problem that requires multi-disciplinary approaches. This research aims to strengthen the interface between water governance and technological and viticulture adaptation approaches. Water resources are shared across regions by stakeholders with varied …

Testing The Correlation Of Trace Element Characteristics With The Petrology And Temperature Of Eruption Of Mid-Miocene Rhyolites In Eastern Oregon, Brianna Christine Young

Dissertations and Theses

The Lake Owyhee Volcanic Field (LOVF) in eastern Oregon experienced several major eruptive events during the mid-Miocene (16.8 to 15.5 Ma), resulting in the emplacement of 3,900 km³ of rhyolitic lava flows and ash-flow tuffs. Eighteen samples from eleven different silicic centers in the LOVF were selected for this study. While all samples of this study are classified as rhyolite, their compositions vary greatly in terms of trace and major elements. Using trace elements, these rhyolite samples are classified as "A-type", described as resulting from "hot and dry" magmas and associated with hot-spot activity, or as "I-type" or "calc-alkaline", …

Dynamic Effects Of Inertial Particles On The Wake Recovery Of A Model Wind Turbine, Sarah E. Smith

Dissertations and Theses

Impacting particles such as rain, dust, and other debris can have devastating structural effects on wind turbines, but little is known about the interaction of such debris within turbine wakes. This study aims to characterize behavior of inertial particles within the turbulent wake of a wind turbine and relative effects on wake recovery. Here a model wind turbine is subjected to varied two-phase inflow conditions, with wind as the carrier fluid (Re_λ = 49 - 88) and polydisperse water droplets (26 to 45µm in diameter) at varied concentrations (Φ_v=0.24 x 10^-5 - 1.3 …

The Rocky Ledge Fault, Shasta County, Ne California: Development And Morphology Of A Quaternary Oblique Normal Fault In Basalt, Gregory David Linscott Martin

Dissertations and Theses

Distinct morphology, variable vertical separation, and unique structural geometries are observed along the Rocky Ledge fault (RLF), an east-dipping, oblique normal fault in the tectonically complex Hat Creek Graben, Shasta County, NE California. Situated in the southern Cascade arc, the RLF is located at the boundary of the Klamath Mountains, Basin and Range, and Walker Lane Seismic Belt. The primary goal of this project is to better understand Quaternary deformation along the RLF. I developed detailed maps of geologic units and structures along the ~15 km length of the RLF. Map data informs assessment of fault geometry, scarp morphology, and …

Droplet Ejections During Wet Lab Operations Aboard Spacecraft, Caleb Cushman Turner

Dissertations and Theses

The breakup and rupture of liquid bridges, thin films, bubbles, droplets, rivulets, and jets can produce satellite droplets that are subsequently ejected into their surrounding environment. For example, when any solid object is withdrawn from a liquid bath, the formation of an ever-thinning columnar liquid bridge eventually ruptures along the axis of the bridge. When rupture occurs under typical pipetting conditions the dynamics governing the rupture almost always produce at a minimum a satellite droplet. When these droplets occur they are often too small and too fast to be observed by the human eye. In a terrestrial environment they are …

Host-Dependent Differences In Replication Strategy Of The Sulfolobus Spindle-Shaped Virus Strain Ssv9 (A.K.A., Ssvk1): Infection Profiles In Hosts Of The Family Sulfolobaceae, Ruben M. Ceballos, Coyne Gareth Drummond, Carson Len Stacy, Elizabeth Padillo-Crespo, Kenneth M. Stedman

Biology Faculty Publications and Presentations

The Sulfolobus Spindle-shaped Virus (SSV) system has become a model for studying thermophilic virus biology, including archaeal host-virus interactions and biogeography. Several factors make the SSV system amenable to studying archaeal genetic mechanisms (e.g., CRISPRs) as well as virus-host interactions in high temperature acidic environments. Previously, we reported that SSVs exhibited differential infectivity on allopatric vs. sympatric hosts. We also noticed a wide host range for virus strain SSV9 (a.k.a., SSVK1). For decades, SSVs have been described as “non-lytic” double-stranded DNA viruses that infect species of the genus Sulfolobus and release virions via budding rather than host lysis. In this …

Memristive Architectures And Algorithms For Approximate Graph-Based Inference, Mohammad M.A. Taha

Dissertations and Theses

The goal of this thesis is to design fast, low-power, robust graph-based inference systems. Our approach to this is by using (1) in-memory computing, (2) approximate computing principles, and (3) memristive devices.

This work is motivated by the fact that conventional von Neumann architectures are not efficient for inference applications, mainly due to the data transfer bottleneck. Adding cache memories and using GPUs is a remedy, however, does not eliminate this bottleneck. In-memory computing is an alternative approach that performs all computations inside the memory, thus eliminating the data transfer bottleneck.

The memristor, which is a passive two-terminal device, is …

Evaluating R&D Projects In Regulated Utilities: The Case Of Power Transmission Utilities, Edwin Garces

Dissertations and Theses

R&D project selection is essential for many organizations; however, it is a complex decision since it is affected by many factors. These factors vary among organizations because of their different objectives and conditions. There are limited budgets for the investments, and the current R&D project selection methods are focused on financial analysis or complex mathematical probabilistic calculations. Therefore, the main motivation of this research is to create a method to help improve the ex-ante selection of R&D projects in regulated organizations. More importantly, the case application is the electric transmission utilities sector, which plays one of the most critical roles …

Spatial Statistical Approaches To Water Quality Modelling, Janardan Mainali

Dissertations and Theses

This dissertation aims to advance the existing knowledge related to spatial modeling of water quality by exploring and introducing innovative approaches to different spatial conceptualizations for water quality modeling and incorporating upstream-downstream relations in geographically weighted regression. By carrying out a systematic literature review of four different classes of spatial models in Chapter One, this dissertation identifies the following major research gaps: lack of incorporation of multiscale processes, not enough emphasis on spatial weights matrices, and unavailability of upstream-downstream relationships in geographically weighted regressions. Chapters Two and Three were designed to address these gaps in the literature. In Chapter Two, …

The Optimization Of Machining Parameters For Milling Operations By Using The Nelder–Mead Simplex Method, Yubin Lee, Alin Resiga, Sung Yi, Chien Wern

Mechanical and Materials Engineering Faculty Publications and Presentations

The purpose of machining operations is to make specific shapes or surface characteristics for a product. Conditions for machining operations were traditionally selected based on geometry and surface finish requirements. However, nowadays, many researchers are optimizing machining parameters since high-quality products can be produced using more expensive and advanced machines and tools. There are a few methods to optimize the machining process, such as minimizing unit production time or cost or maximizing profit. This research focused on maximizing the profit of computer numerical control (CNC) milling operations by optimizing machining parameters. Cutting speeds and feed are considered as the main …

Teachers’ Perspectives On Year Two Implementation Of A Kindergarten Readiness Assessment, Rachel E. Schachter, Erin E. Flynn, Amy R. Napoli, Shayne B. Piasta

School of Social Work Faculty Publications and Presentations

In this study we examined teachers’ perspectives regarding the second year of implementing a Kindergarten Readiness Assessment (KRA). Using a mixed-methods approach, we focused on the administration process, the perceived benefits of the assessment, and how teachers used the assessment to inform instruction. We also investigated whether these differed by teacher and district characteristics and how KRA experiences were different in the second year of implementation. Research Findings: Teachers generally did not view the KRA as beneficial for instruction or for students, reporting administration difficulties, inadequate KRA content, and limited utility of KRA data for supporting instruction as ongoing …

Addressing Parameter Uncertainty In Sd Models With Fit-To-History And Monte-Carlo Sensitivity Methods, Wayne Wakeland, Jack Homer

Complex Systems Faculty Publications and Presentations

We present a practical guide, including a step-by-step flowchart, for establishing uncertainty intervals for key model outcomes in the face of uncertain parameters. The process starts with Powell optimization (e.g., using VensimTM) to find a set of uncertain parameters (the “optimum” parameter set or OPS) that minimize the model fitness error relative to available reference behavior data. The optimization process also helps in refinement of assumed parameter uncertainty ranges. Next, Markov Chain Monte Carlo (MCMC) or conventional Monte Carlo (MC) randomization is used to create a sample of parameter sets that fit the reference behavior data nearly as well as …