Digital Commons Network^™

Spectral Discretization Errors In Filtered Subspace Iteration, Jay Gopalakrishnan, Luka Grubišić, Jeffrey S. Ovall

Mathematics and Statistics Faculty Publications and Presentations

We consider filtered subspace iteration for approximating a cluster of eigenvalues (and its associated eigenspace) of a (possibly unbounded) selfadjoint operator in a Hilbert space. The algorithm is motivated by a quadrature approximation of an operator-valued contour integral of the resolvent. Resolvents on infinite dimensional spaces are discretized in computable finite-dimensional spaces before the algorithm is applied. This study focuses on how such discretizations result in errors in the eigenspace approximations computed by the algorithm. The computed eigenspace is then used to obtain approximations of the eigenvalue cluster. Bounds for the Hausdorff distance between the computed and exact eigenvalue clusters …

What If Our Beliefs About A System Are Not Wholly Accurate? What If?, Gary Langford

Systems Science Friday Noon Seminar Series

For most people, a system is a construct with vexing complexities, many many parts, and perhaps wrapped with a goal or intention. Add to that simple construct a set of terminologies that are commonly applied when speaking of “systems” and we just might have veered away from discoveries of imminent importance. Ask yourself, “You said it was a system, but how did that statement help you solve your problem? How far off would we have to be in our perception of systemsness for us to make mistakes of consequence? One Hundred Billion are lost annually in software projects that failed …

Analysis Of Feast Spectral Approximations Using The Dpg Discretization, Jay Gopalakrishnan, Luka Grubišić, Jeffrey S. Ovall, Benjamin Quanah Parker

Mathematics and Statistics Faculty Publications and Presentations

A filtered subspace iteration for computing a cluster of eigenvalues and its accompanying eigenspace, known as “FEAST”, has gained considerable attention in recent years. This work studies issues that arise when FEAST is applied to compute part of the spectrum of an unbounded partial differential operator. Specifically, when the resolvent of the partial differential operator is approximated by the discontinuous Petrov Galerkin (DPG) method, it is shown that there is no spectral pollution. The theory also provides bounds on the discretization errors in the spectral approximations. Numerical experiments for simple operators illustrate the theory and also indicate the value of …

Equalization Of Four Cardiovascular Risk Algorithms After Systematic Recalibration: Individual-Participant Meta-Analysis Of 86 Prospective Studies, Lisa Pennells, Stephen Kaptoge, Angela Wood, Mike Sweeting, Xinghui Zhao, Carlos J. Crespo, Multiple Additional Authors

OHSU-PSU School of Public Health Faculty Publications and Presentations

Aims: There is debate about the optimum algorithm for cardiovascular disease (CVD) risk estimation. We conducted head-to-head comparisons of four algorithms recommended by primary prevention guidelines, before and after ‘recalibration’, a method that adapts risk algorithms to take account of differences in the risk characteristics of the populations being studied.

Methods and results: Using individual-participant data on 360 737 participants without CVD at baseline in 86 prospective studies from 22 countries, we compared the Framingham risk score (FRS), Systematic COronary Risk Evaluation (SCORE), pooled cohort equations (PCE), and Reynolds risk score (RRS). We calculated measures of risk discrimination …

4-D Computational Modeling Of Cardiac Outflow Tract Hemodynamics Over Looping Developmental Stages In Chicken Embryos, Katherine Courchaine, Mackenzie J. Gray, Kaitlin Beel, Kent L. Thornburg, Sandra Rugonyi

OHSU-PSU School of Public Health Faculty Publications and Presentations

Cardiogenesis is interdependent with blood flow within the embryonic system. Recently, a number of studies have begun to elucidate the effects of hemodynamic forces acting upon and within cells as the cardiovascular system begins to develop. Changes in flow are picked up by mechanosensors in endocardial cells exposed to wall shear stress (the tangential force exerted by blood flow) and by myocardial and mesenchymal cells exposed to cyclic strain (deformation). Mechanosensors stimulate a variety of mechanotransduction pathways which elicit functional cellular responses in order to coordinate the structural development of the heart and cardiovascular system. The looping stages of heart …

Raps Sheet, February 2019, Retirement Association Of Portland State

RAPS Sheet: Monthly Newsletter

No abstract provided.

Viscosities, Diffusion Coefficients, And Mixing Times Of Intrinsic Fluorescent Organic Molecules In Brown Limonene Secondary Organic Aerosol And Tests Of The Stokes–Einstein Equation, Dagny A. Ullmann, Mallory L. Hinks, Adrian M. Maclean, Christopher Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Sergey A. Nizkorodov, Saeid Kamal, Allan K. Bertram

Physics Faculty Publications and Presentations

Viscosities and diffusion rates of organics within secondary organic aerosol (SOA) remain uncertain. Using the bead-mobility technique, we measured viscosities as a function of water activity (a_w) of SOA generated by the ozonolysis of limonene followed by browning by exposure to NH₃ (referred to as brown limonene SOA or brown LSOA). These measurements together with viscosity measurements reported in the literature show that the viscosity of brown LSOA increases by 3–5 orders of magnitude as the aw decreases from 0.9 to approximately 0.05. In addition, we measured diffusion coefficients of intrinsic fluorescent organic molecules within brown …

Parallelized Particle Swarm Optimization To Estimate The Heat Transfer Coefficients Of Palm Oil, Canola Oil, Conventional, And Accelerated Petroleum Oil Quenchants, Zoltán Fried, Imre Felde, Rosa L. Simencio Otero, Jônatas M. Viscaino, George E. Totten, Lauralice Canale

Mechanical and Materials Engineering Faculty Publications and Presentations

An inverse solver for the estimation of the temporal-spatial heat transfer coefficients (HTC), without using prior information of the thermal boundary conditions, was used for immersion quenching into palm oil, canola oil, and two commercial petroleum oil quenchants. The particle swarm optimization (PSO) method was used on near-surface temperature-time cooling curve data obtained with the so-called Tensi multithermocouple, and a 12.5 by 45 mm Inconel 600 probe. The fitness function to be minimized by a PSO approach is defined by the deviation of the measured and calculated cooling curves. The PSO algorithm was parallelized and implemented on a graphics accelerator …

Artificial Intelligence Hits The Barrier Of Meaning, Melanie Mitchell

Computer Science Faculty Publications and Presentations

Today’s AI systems sorely lack the essence of human intelligence: Understanding the situations we experience, being able to grasp their meaning. The lack of humanlike understanding in machines is underscored by recent studies demonstrating lack of robustness of state-of-the-art deep-learning systems. Deeper networks and larger datasets alone are not likely to unlock AI’s “barrier of meaning”; instead the field will need to embrace its original roots as an interdisciplinary science of intelligence.

Inferring And Explaining, Jeffery L. Johnson

PDXOpen: Open Educational Resources

Inferring and Explaining is a book in practical epistemology. It examines the notion of evidence and assumes that good evidence is the essence of rational thinking. Evidence is the cornerstone of the natural, social, and behavioral sciences. But it is equally central to almost all academic pursuits and, perhaps most importantly, to the basic need to live an intelligent and reflective life.

The book further assumes that a particular model of evidence— Inference to the Best Explanation—not only captures the essence of (good) evidence but suggests a very practical, and pedagogically useful, procedure for evidence evaluation. The book is intended …

Spectral Clustering For Electrical Phase Identification Using Advanced Metering Infrastructure Voltage Time Series, Logan Blakely

Dissertations and Theses

The increasing demand for and prevalence of distributed energy resources (DER) such as solar power, electric vehicles, and energy storage, present a unique set of challenges for integration into a legacy power grid, and accurate models of the low-voltage distribution systems are critical for accurate simulations of DER. Accurate labeling of the phase connections for each customer in a utility model is one area of grid topology that is known to have errors and has implications for the safety, efficiency, and hosting capacity of a distribution system. This research presents a methodology for the phase identification of customers solely using …

The Complexities Of Open Data, Hector Dominguez

Systems Science Friday Noon Seminar Series

Hector Dominguez is the current Open Data Coordinator at the City of Portland, and there are several lessons learned and strategies developed in the several months of work in this position. Hector will share some challenges on creating trusted and reliable data and information services, as well as the opportunities to work with Urban Data to resolve city challenges and to support achieving the City's goals in the coming years.

In this talk, Hector will share how modeling and defining the right metrics are not the only factors to implementing a citywide program, but rather, how ethics, communications and strategy …

Knowing Without Knowing: Real-Time Usage Identification Of Computer Systems, Leila Mohammed Hawana

Dissertations and Theses

Contemporary computers attempt to understand a user's actions and preferences in order to make decisions that better serve the user. In pursuit of this goal, computers can make observations that range from simple pattern recognition to listening in on conversations without the device being intentionally active. While these developments are incredibly useful for customization, the inherent security risks involving personal data are not always worth it. This thesis attempts to tackle one issue in this domain, computer usage identification, and presents a solution that identifies high-level usage of a system at any given moment without looking into any personal data. …

From Drought To Food-Energy-Water-Security Nexus: An Assessment Of Food Insecurity In The Middle East, Maysoun Ayad Hameed

Dissertations and Theses

Drought is an extreme climate phenomenon that happens slowly and periodically threatens the environmental and socio-economic sectors. Developing countries have experienced crucial conditions in meeting the needs for food, energy, and water security. Natural disasters contribute as risky sources of food insecurity and vulnerability in the Middle East. This dissertation presents a country-level review and quantitative assessment of the current issues associated with the Food-Energy-Water-Security (FEWS) Nexus in the Middle East. In this study, sixteen countries in the Middle East are chosen, namely, Arabian Peninsula, Iran, Syria, Lebanon, Israel, Palestine, Egypt, and Turkey. The most recent datasets are used to …

Dc-Rts Noise: Observation And Analysis, Benjamin William Hendrickson

Dissertations and Theses

Dark current random telegraph signal (DC-RTS) is a physical phenomenon that effects the performance of solid state image sensors. Identified by meta-stable stochastic switching between two or more dark current levels, DC-RTS is an emerging concern for device scientists and manufacturers as a limiting noise source. Observed and studied in both charge coupled devices (CCDs) and complementary metal-oxide-semiconductor (CMOS) image sensors, the metastable defects inside the device structure that give rise to this switching phenomenon are known to be derived from radiation damage. An examination of the relationship between high energy photon damage and these RTS defects is presented and …

Latent Space Models For Temporal Networks, Jasper Alt

Systems Science Friday Noon Seminar Series

In many contexts we may expect the structure of networks to be derived from some kind of abstract distance between actors. We refer to this phenomenon as homophily: like nodes connect to like. For example, people with similar beliefs may be more likely to form social relations.

We formalize this notion by positioning the nodes in a latent space representing the possible values of the homophilous attributes. Realistically, we should expect latent attributes like beliefs to change over time in some nontrivial way, and the structures of temporal networks to evolve accordingly. We introduce a model of latent space dynamics …

Faculty Senate Monthly Packet January 2019, Portland State University Faculty Senate

Faculty Senate Monthly Packets

The January 2019 Monthly packet includes the January agenda and appendices and the Faculty Senate minutes and attachments from the meeting held December 3, 2018.

Rapid Serial Visual Presentation Interacts With Ambiguity During Sentence Comprehension, Sarah Key-Delyria, Todd Bodner, Lori J. P. Altmann

Psychology Faculty Publications and Presentations

Conventional opinion about using Rapid Serial Visual Presentation (RSVP) for examining sentence comprehension maintains that RSVP taxes working memory (WM), which probably affects sentence processing. However, most RSVP studies only infer the involvement of WM. Other cognitive resources, such as cognitive control or vocabulary may also impact sentence comprehension and interact with RSVP. Further, sentence ambiguity is predicted to interact with RSVP and cognitive resources to impact sentence comprehension. To test these relationships, participants read ambiguous and unambiguous sentences using RSVP and Whole-Sentence presentation, followed by comprehension questions that were targeted to the ambiguous region of the sentences. Presentation type …

Evaluating The Impact And Distribution Of Stormwater Green Infrastructure On Watershed Outflow, Benjamin Fahy

Dissertations and Theses

Green Stormwater Infrastructure (GSI) has become a popular method for flood mitigation as it can prevent runoff from entering streams during heavy precipitation. In this study, a recently developed neighborhood in Gresham, Oregon hosts a comparison of various GSI projects on runoff dynamics. The study site includes dispersed GSI (rain gardens, retention chambers, green streets) and centralized GSI (bioswales, detention ponds, detention pipes). For the 2017-2018 water year, hourly rainfall and observed discharge data is used to calibrate the EPA's Stormwater Management Model to simulate rainfall-runoff dynamics, achieving a Nash-Sutcliffe efficiency of 0.75 and Probability Bias statistic of 3.3%. A …

Psu Green Building Internship Final Presentation, 2019: Kmc Post-Occupancy Study, Junyoung Lee, Everett Stilley

Campus Sustainability Office Publications, Reports and Presentations

Survey students taking classes in Pavilion classrooms during summer 2019 term. Analyze data to update classroom scheduling recommendations.

Fine-Scale Assessment Of Cross-Boundary Wildfire Events In The Western United States, Palaiologos Palaiologou, Alan A. Ager, Cody Evers, Max Nielsen-Pincus, Michelle A. Day, Haiganoush K. Preisler

Environmental Science and Management Faculty Publications and Presentations

We report a fine-scale assessment of cross-boundary wildfire events for the western US. We used simulation modeling to quantify the extent of fire exchange among major federal, state, and private land tenures and mapped locations where fire ignitions can potentially affect populated places. We examined how parcel size affects wildfire transmission and partitioned the relative amounts of transmitted fire between human and natural ignitions. We estimated that 85 % of the total predicted wildfire activity, as measured by area burned, originates from four land tenures (Forest Service, Bureau of Land Management, private, and state lands) and 63 % of the …

Curriculum Change 2019-2020, Portland State University

Bulletin & Curriculum Change Documents

No abstract provided.

Exploring And Expanding The One-Pixel Attack, Umairullah Khan, Walt Woods

Maseeh Summer Undergraduate Research Experience

In machine learning research, adversarial examples are normal inputs to a classifier that have been specifically perturbed to cause the model to misclassify the input. These perturbations rarely affect the human readability of an input, even though the model’s output is drastically different. Recent work has demonstrated that image-classifying deep neural networks (DNNs) can be reliably fooled with the modification of a single pixel in the input image, without knowledge of a DNN’s internal parameters. This “one-pixel attack” utilizes an iterative evolutionary optimizer known as differential evolution (DE) to find the most effective pixel to perturb, via the evaluation of …

Volcanic Glass As A Proxy For Cenozoic Elevation And Climate In The Cascade Mountains, Oregon, Usa, John Bershaw, Elizabeth J. Cassell, Tessa Boe Carlson, Ashley R. Streig, Martin J. Streck

Geology Faculty Publications and Presentations

After deposition, volcanic glass hydrates with ambient water, recording the average hydrogen isotope ratio (δD or δ2H) of local meteoric water during the hydration period. Previous researchers have used ancient glass δD values to reconstruct paleotopography and paleoclimate, while others have questioned the long-term reliability of the proxy as a recorder of ancient meteoric water. In this study, we sampled volcanic glasses ranging in age ~33 Ma to(east) side of the Oregon Cascade Mountains. Our results strongly suggest that volcanic glass acquires and preserves δD values that are proportional to the stable isotopic composition of environmental water at the time …

Globally Detected Volcanic Lightning And Umbrella Dynamics During The 2014 Eruption Of Kelud, Indonesia, Kirstin A. Hargie, Alexa R. Van Eaton, L. G. Mastin, Robert H. Holzworth, John W. Ewert, Michael Pavolonis

Geology Faculty Publications and Presentations

Volcanic lightning shows considerable promise as a monitoring and research tool to characterize explosive eruptions. Its key strengths are rapid and remote detection, because the radio signals produced by lightning can propagate thousands of km at the speed of light. Despite these tantalizing properties, the scientific work on volcanic lightning has only recently started gaining momentum. Much more is needed to understand what lightning reveals about the evolution of an eruption in near-real time. Here we examine the timing and energy release of lightning generated by the eruption of Kelud volcano in Indonesia on 13 February 2014, as detected by …

A Bayesian Nonparametric Multiple Testing Procedure For Comparing Several Treatments Against A Control, Luis Gutiérrez, Andrés Barrientos, Jorge González, Daniel Taylor-Rodríguez

Mathematics and Statistics Faculty Publications and Presentations

We propose a Bayesian nonparametric strategy to test for differences between a control group and several treatment regimes. Most of the existing tests for this type of comparison are based on the differences between location parameters. In contrast, our approach identifies differences across the entire distribution, avoids strong modeling assumptions over the distributions for each treatment, and accounts for multiple testing through the prior distribution on the space of hypotheses. The proposal is compared to other commonly used hypothesis testing procedures under simulated scenarios. Two real applications are also analyzed with the proposed methodology.

Stability Conditions For Coupled Oscillators In Linear Arrays, Pablo Enrique Baldivieso Blanco, J.J.P. Veerman

Mathematics and Statistics Faculty Publications and Presentations

In this paper, we give necessary conditions for stability of flocks in R. We focus on linear arrays with decentralized agents, where each agent interacts with only a few its neighbors. We obtain explicit expressions for necessary conditions for asymptotic stability in the case that the systems consists of a periodic arrangement of two or three different types of agents, i.e. configurations as follows: ...2-1-2-1 or ...3-2-1-3-2-1. Previous literature indicated that the (necessary) condition for stability in the case of a single agent (...1-1-1) held that the first moment of certain coefficients governing the interactions between agents has to be …

Effects Of Water Level Fluctuation On Thermal Stratification In A Typical Tributary Bay Of Three Gorges Reservoir, China, Juxiang Jin, Scott Wells, Defu Liu, Guolu Yang, Senlin Zhu, Jun Ma, Zhengjian Yang

Civil and Environmental Engineering Faculty Publications and Presentations

Xiangxi River is a typical tributary of Three Gorges Reservoir (TGR) in China. Based on field observations in 2010, thermal stratification was significant in most months of the year. Through field data analysis and numerical simulations, the seasonal and spatial variation of thermal stratification as related to the impact of the operation of TGR were investigated. Thermal stratification was most pronounced from April to September in the Xiangxi River tributary. Air temperature (AT) and water level (WL) were the two dominant variables impacting thermal stratification. AT affected the surface water temperature promoting the formation of thermal stratification, and high WLs …

Developing A Framework To Assess Renewable Energy Options For Higher Education Institutions: Values-Based Recommendations For Portland State University, Emily Quinton

Environmental Science and Management Professional Master's Project Reports

Taking voluntary action to increase renewable use is necessary for higher education institutions to meet carbon reduction goals. Options for increasing renewable energy are largely defined by state-level utility regulation as well as local and institutional electricity providers. This project contained three major stages: 1) determine renewable energy procurement and development options available to Portland State; 2) evaluate these options using a values-based assessment; and 3) develop recommendations and next steps for University stakeholders. Final recommendations include pursuing the Portland General Electric green tariff, directly sourcing renewable energy through PSU's direct access contract, and more.

Utility Summary Fiscal Year 2019, Campus Sustainability Office

Campus Sustainability Office Publications, Reports and Presentations

Summary of energy usage listed by building.