Digital Commons Network^™

Wind Tunnel Research, Dynamics, And Scaling For Wind Energy, Majid Bastankhah, Raul Bayoan Cal, Nicholas Hamilton

Mechanical and Materials Engineering Faculty Publications and Presentations

The interaction of wind turbines with turbulent atmospheric boundary layer (ABL) flows represents a complex multi-scale problem that spans several orders of magnitudes of spatial and temporal scales. These scales range from the interactions of large wind farms with the ABL (on the order of tens of kilometers) to the small length scale of the wind turbine blade boundary layer (order of a millimeter). Detailed studies of multi-scale wind energy aerodynamics are timely and vital to maximize the efficiency of current and future wind energy projects, be they onshore, bottom-fixed offshore, or floating offshore. Among different research modalities, wind tunnel …

Applying Biomimetic Passive Dynamics To A Quadruped Robot Leg, Emma Krnacik

Dissertations and Theses

The study of synthetic nervous systems is an emerging field within biomimetic robotics as an alternative to more classic control techniques. As the modeling of these nervous systems becomes more accurate, it is important to note that the nervous system and physical system co-evolved and continue to operate in an interdependent fashion. Many legged robots, including the existing quadruped in the AARL, have leg systems that may have similar geometrical properties to that of a mammal, but have significantly different dynamic properties. This paper presents a method for designing a limb so that the passive dynamics more accurately represent that …

Wind Plant Controls, Nicholas Hamilton, Dennice Gayme, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

The development of operational strategies for wind farms as an integrated plant system to achieve a variety of goals from elevating power production to reducing maintenance needs has generated a great deal of interest in recent years. Achieving these operational goals requires an estimate of the energy available and the wind conditions affecting each turbine. The importance of the aerodynamic interaction of wind turbines with the dynamic atmospheric resource means that wakes (the momentum deficit due to power extraction) and their interactions through the farm have the largest influence on the available energy. Predicting the influence of wakes and their …

Splitting Gaussian Densities To Minimize Variance Along A Direction Of Nonlinearity, Amit Kumar

Dissertations and Theses

Nonlinear functions of random vectors are frequently used in signal processing, and especially in state space tracking algorithms. Many of these algorithms require a way of estimating the probability density of the state vector at the output of the nonlinear function. Algorithms derived from Kalman Filter, such as Extended Kalman Filter and Unscented Kalman Filter, are popular choices for this, but they only estimate mean and covariance which may be insufficient to describe the non-Gaussian densities. On the other hand, Monte Carlo methods such as particle filters can be more capable but require much more computation. Gaussian mixture filters aim …

Domain Knowledge As Motion-Aware Inductive Bias For Deep Video Synthesis: Two Case Studies, Long Mai

Dissertations and Theses

Deep neural networks have been part of many breakthroughs in computer graphics and vision research. In the context of visual content synthesis, deep learning models have achieved impressive performance in the image domain. However, adapting the successes of image synthesis models to the video domain has been difficult, arguably due to the lack of sufficiently strong inductive biases that encourage the models to capture the temporal-dynamic nature of video data. Inductive bias refers to the prior knowledge incorporated into the learning models to explicitly drive the learning process toward the solutions that capture meaningful structures from data, which is critical …

Remote Sensing Evidence For Significant Variations In The Global Gross Domestic Product During The Covid-19 Epidemic, Bin Guo, Wencai Zhang, Lin Pei, Xiaowei Zhu, Pingping Luo, Weili Duan

Mechanical and Materials Engineering Faculty Publications and Presentations

Coronavirus disease 2019 (COVID-19) has been spreading rapidly and is still threatening human health currently. A series of measures for restraining epidemic spreading has been adopted throughout the world, which seriously impacted the gross domestic product (GDP) globally. However, details of the changes in the GDP and its spatial heterogeneity characteristics on a fine scale worldwide during the pandemic are still uncertain. We designed a novel scheme to simulate a 0.1° × 0.1° resolution grid global GDP map during the COVID-19 pandemic. Simulated nighttime-light remotely sensed data (SNTL) was forecasted via a GM(1, 1) model under the assumption that there …

Collective Proving Activity In A Synchronous Online Environment, Tenchita Alzaga Elizondo

Dissertations and Theses

Given the well documented fact students often struggle with proof and proof-related activity for various reasons, more educators have shifted to incorporating pedagogies involving collaborative learning given their benefits to student learning. However, there is still surprisingly little research focused on the nature of students' collaborative proving activity. Moreover, the recent COVID-19 pandemic, and subsequent shift to remote learning, forced educators and students to adapt and learn how to work within a new learning environment. In this dissertation project, I investigate how students engage in collaborative proving activity in a synchronous online introduction to proofs course. In the first paper, …

Securing Humane Values At Yale, Bennett B. Gilbert

University Studies Faculty Publications and Presentations

For four days in the first week of November, the Yale administration closed the Schwarzman Center and the Good Life Center in the Schwarzman Center to celebrate Stephen Schwarzman and his donation to renovate the building he wanted named after himself. The Commons at the Schwarzman Center used to be called University Commons, a name that indicated its place at the center of Yale life as common ground. As he did in giving money for the renovation of the New York Public Library, when he insisted that his name be carved on its stone entrance beneath the names of the …

Faculty Senate Monthly Packet November 2022, Portland State University Faculty Senate

Faculty Senate Monthly Packets

The November 7, 2022 Monthly packet includes the November agenda and appendices and the Faculty Senate minutes and attachments from the meeting held October 3, 2022.

Quantum Key-Length Extension, Joseph Jaeger, Fang Song, Stefano Tessaro

Computer Science Faculty Publications and Presentations

Should quantum computers become available, they will reduce the effective key length of basic secret-key primitives, such as blockciphers. To address this we will either need to use blockciphers with inherently longer keys or develop key-length extension techniques to amplify the security of a blockcipher to use longer keys.

We consider the latter approach and revisit the FX and double encryption constructions. Classically, FX was proven to be a secure key-length extension technique, while double encryption fails to be more secure than single encryption due to a meet-in-the-middle attack. In this work we provide positive results, with concrete and tight …

System-Level Risk Management Of Transportation Structures And Networks, David Y. Yang

PSU Transportation Seminars

Conventional risk assessment approaches in infrastructure management do not fully capture the system-level impact of structural failure or service disruption. As a result, the priorities of preservation projects may be misidentified, leading to suboptimal maintenance schedules and waste of resources. In this presentation, we will first illustrate why conventional risk assessment is not suitable for transportation structures and networks due to interdependency between assets, and then demonstrate how system-level preservation policies can be devised using novel algorithms adapted from the field of deep reinforcement learning. Results from a series of case studies showcase that the system-level risk management is essential …

Arts Course-Taking And Math Achievement In Us High Schools With Daniel Mackin Freeman, Daniel Mackin Freeman

PDXPLORES Podcast

In this episode of PDXPLORES, Daniel Mackin Freeman, a Ph. D. candidate in the sociology department at Portland State University, discusses the results of a study that asked if fine arts coursework is positively correlated to mathematics achievement in high schools at low, middle, and high socio-economic levels. Freeman and PSU sociology professor, Dara Shifrer recently publish the results of their study, "Arts for Whose Sake? Arts Course-taking and Math Achievement in US High Schools," online in Sociological Perspectives.

Click on the "Download" button to access the audio transcript.

Pile-Supported Wharves Subjected To Inertial Loads And Lateral Ground Deformations. Ii: Guidelines For Equivalent Static Analysis, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Scott Schlechter, Nason Mccullough

Civil and Environmental Engineering Faculty Publications and Presentations

An equivalent static analysis (ESA) procedure is proposed for the design of pile-supported wharves subjected to combined inertial and kinematic loads during earthquakes. The accuracy of the ESA procedure was evaluated against measurements from five large-scale centrifuge tests. The wharf structures in these tests were subjected to a suite of recorded ground motions and the associated superstructure inertia, as well as earthquake-induced slope deformations of varying magnitudes. It is shown that large bending moments at depths greater than 10 pile diameters were primarily induced by kinematic demands and can be estimated by applying soil displacements only (i.e., 100% kinematic). In …

Pile-Supported Wharves Subjected To Inertial Loads And Lateral Ground Deformations. I: Experimental Results From Centrifuge Tests, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Scott Schlechter, Nason Mccullough

Civil and Environmental Engineering Faculty Publications and Presentations

Five dynamic, large-scale centrifuge tests on pile-supported wharves were used to investigate the time- and depth-dependent nature of kinematic and inertial demands on the deep foundations during earthquake loading. The wharf structures in the physical experiments were subjected to a suite of recorded ground motions and imposed superstructure inertial demands on the piles. Partial to full liquefaction in loose sand resulted in slope deformations of varying magnitudes that imposed kinematic demands on the piles. It was found that the wharf inertia and soil displacements were always in phase during the critical cycle when bending moments were at their maximum values. …

Selected Topics Of The Past Thirty Years In Ocean Acoustics, Michael D. Collins, Altan Turgut, Michael J. Buckingham, Peter Gerstoft, Martin Siderius

Electrical and Computer Engineering Faculty Publications and Presentations

This paper reviews some of the highlights of selected topics in ocean acoustics during the thirty years that have passed since the founding of the Journal of Theoretical and Computational Acoustics. Advances in computational methods and computers helped to make computational ocean acoustics a vibrant area of research during that period. The parabolic equation method provides an unrivaled combination of accuracy and efficiency for propagation problems in which the bathymetry, sound speed, and other environmental parameters vary in the horizontal directions. The extension of this approach to cases involving layers that support shear waves has been an active area …

Real-Time Joint Ocean Acoustics And Circulation Modeling In The 2021 New England Shelf Break Acoustics Experiment (L), Brendan J. Decourcy, Ying-Tsong Lin, Weifeng Gordon Zhang, Emma Reeves Ozanich, Natalie Kukshtel, Martin Siderius, Glen Gawarkiewicz, Jacob Forsyth

Electrical and Computer Engineering Faculty Publications and Presentations

During the spring of 2021, a coordinated multi-vessel effort was organized to study physical oceanography, marine geology and biology, and acoustics on the northeast United States continental shelf, as part of the New England Shelf Break Acoustics (NESBA) experiment. One scientific goal was to establish a real-time numerical model aboard the research vessel with high spatial and temporal resolution to predict the oceanography and sound propagation within the NESBA study area. The real-time forecast model performance and challenges are reported in this letter without adjustment or re-simulation after the cruise. Future research directions for post-experiment studies are also suggested.

Cyclic Porewater Pressure Generation In Intact Silty Soils, Arash Khosravifar, Stephen Dickenson, Diane Moug

Civil and Environmental Engineering Faculty Publications and Presentations

The results of cyclic strain-controlled, constant volume direct simple shear (CDSS) tests and field shaking tests have been evaluated for intact, natural, low-plastic silts from six different fine-grained soils with 54%–100% fines content, 47%–83% silt content, and plasticity indices (PI) ranging from nonplastic to 16. These tests constitute a subset of a larger archive of CDSS tests performed on silt deposits from the Pacific Northwest, British Columbia, and Alaska collected and analyzed by the co-authors. The cyclic data are presented in this paper for two objectives: (a) to characterize cyclically-induced excess pore pressure generation in intermediate soils with various soil …

"It Made Me Feel Like Things Are Starting To Change In Society:" A Qualitative Study To Foster Positive Patient Experiences During Phone-Based Social Needs Interventions, Anna Steeves-Reece, Christina Nicolaidis, Dawn M. Richardson, Melissa Frangie, Katherin Gomez-Arboleda, Chrystal Barnes, Minnie Kang, Bruce Goldberg, Stephan Lindner, Melinda M. Davis

School of Social Work Faculty Publications and Presentations

Many healthcare organizations are screening patients for health-related social needs (HRSN) to improve healthcare quality and outcomes. Due to both the COVID-19 pandemic and limited time during clinical visits, much of this screening is now happening by phone. To promote healing and avoid harm, it is vital to understand patient experiences and recommendations regarding these activities. We conducted a pragmatic qualitative study with patients who had participated in a HRSN intervention. We applied maximum variation sampling, completed recruitment and interviews by phone, and carried out an inductive reflexive thematic analysis. From August to November 2021 we interviewed 34 patients, developed …

A Multi-Modal Volumetric Microscope With Automated Sample Handling For Surveying Microbial Life In Liquid Samples, Nathan Oborny, Eugene Serabyn, J. Kent Wallace, Kurt Liewer, Manuel Bedrossian, Stephanie Rider, Chris Lindensmith, Jay Nadeau, Multiple Additional Authors

Physics Faculty Publications and Presentations

In the study of microbial life, microscopy plays a unique role due to its ability to detect ordered structure, motility, and fluorescence signals. As such it has also recently gained attention in the context of searching for extant life on distant Solar System bodies bearing liquid water. In this paper we introduce a multimodal volumetric microscopy system for potential future spaceflight missions that combines digital holographic microscopy (DHM) and volume fluorescence imager (VFI), which are volumetric imaging methods that provide highresolution, high-throughput examination of liquid samples. DHM provides information on the absorption, morphology, and motility of imaged objects without requiring …

Freight Moves The Oregon Economy, Becky Knudson

PSU Transportation Seminars

This presentation provides a broad overview of work conducted by the Oregon Department of Transportation in the field of freight analysis supporting long range planning. The information shared will touch upon the data and tools used to conduct analysis, describe the importance of economic context, and share examples from a range of different analyses. Content will be geared toward building understanding of how analysis is used to guide data-driven decision making in the public transportation sector. The presentation will highlight the importance of testing potential public policy to avoid unintended consequences, evaluate tradeoffs across different policy objectives, and test policy …

River Discharge Mediates Extent Of Phytoplankton And Harmful Algal Bloom Habitat In The Columbia River Estuary (Usa) During North Pacific Marine Heat Waves, Taylor N. Dodrill, Yangdong Pan, Tawnya D. Peterson

Environmental Science and Management Faculty Publications and Presentations

Marine heat waves (MHWs) have been associated with extensive harmful algal blooms (HABs) in the northeast Pacifc Ocean, but the degree to which these large-scale oceanographic events are mirrored in nearshore environments has not been well established. We compared phytoplankton assemblages in the Lower Columbia River Estuary (LCRE) during two Pacifc MHWs that took place in 2015 and 2019, with observations from 2017, a year with no MHW. These data were paired with environmental data from the summers of 2015–2019 to characterize differences in estuarine conditions during MHWs that promote phytoplankton assemblage transitions and identify HAB-conducive conditions. Bloom densities of …

Visualization Of Cathode Spot Control Using Laser Irradiation And Oxide Addition In Wire Arc Additive Manufacturing Of Titanium Alloys, Tae Hyun Lee, Cheolhee Kim, Je Hoon Oh, Dong Hyuck Kam

Mechanical and Materials Engineering Faculty Publications and Presentations

Arc instability is one of the most critical problems in gas-metal-arc (GMA) based wire arc additive manufacturing of titanium (Ti) alloys. It can result in a poor bead surface, surface oxidation, and spattering. In particular, the relocation of the cathode spot area is the main cause of big spatters because of the high thermal energy of the molten droplet at the molten pool surface. In this study, two cathode spot control techniques were applied using auxiliary laser heating and prelaid oxides, and the behaviors of the cathode spots and arc were visualized using high-speed photography. When the laser beam was …

Webinar: Community Transportation Academies: Rethinking Effective Community Engagement Around Transportation Decision-Making, Nathan Mcneil, Keith Bartholomew, Andrea Olson, Laura Hanson, Thuy Tu

TREC Webinar Series

This webinar will introduce you to the concept of the Community Transportation Academy (CTA), a model which has been operating in Portland for over 30 years in the form of the Portland Traffic and Transportation (PTT) class. Now catching on in other cities, the project team recently implemented the Wasatch Transportation Academy (WTA) in Salt Lake City. The presenters also include key stakeholders (and guest lecturers) in the WTA, and the PTT instructor. The presentation will include discussions about why CTAs can be good for both community members and transportation agencies/practitioners, and how you can bring a CTA to your …

Bringing Complete Streets To Reality In State Transportation Projects, Celeste Gilman

PSU Transportation Seminars

In order to improve the safety, mobility, and accessibility of state highways, the Washington State legislature directed Washington State Department of Transportation (WSDOT) to incorporate the principles of complete streets in state transportation projects and to plan, design, and construct facilities that provide street access with all users in mind, including pedestrians, bicyclists, and public transportation users. This new requirement was passed as part of the Move Ahead Washington package in the 2022 legislative session and is effective for state transportation projects starting design on or after July 1, 2022 with a project cost of $500,000 or more. This provides …

Factors Influencing Terrestriality In Primates Of The Americas And Madagascar, Timothy M. Eppley, Selwyn Hoeks, Colin A. Chapman, Joerg U. Ganzhorn, Katie Hall, Megan A. Owen, Dara B. Adams, Néstor Allgas, Multiple Additional Authors

Anthropology Faculty Publications and Presentations

Among mammals, the order Primates is exceptional in having a high taxonomic richness in which the taxa are arboreal, semiterrestrial, or terrestrial. Although habitual terrestriality is pervasive among the apes and African and Asian monkeys (catarrhines), it is largely absent among monkeys of the Americas (platyrrhines), as well as galagos, lemurs, and lorises (strepsirrhines), which are mostly arboreal. Numerous ecological drivers and species-specific factors are suggested to set the conditions for an evolutionary shift from arboreality to terrestriality, and current environmental conditions may provide analogous scenarios to those transitional periods. Therefore, we investigated predominantly arboreal, diurnal primate genera from the …

Faculty Senate Monthly Packet October 2022, Portland State University Faculty Senate

Faculty Senate Monthly Packets

The October 2022 Monthly packet includes the October agenda and appendices and the Faculty Senate minutes and attachments from the meeting held June 6, 2022.

Special Issue Introduction: Writing Infrastructure, Sarah Read, Jordan Frith

English Faculty Publications and Presentations

This article is the introduction to the second of two Communication and Design Quarterly special issues focused on conceptualizations of infrastructure. While there are more continuities than differences between the themes and methodologies of articles in the first and second issues, this second issue leans towards articles that have taken up infrastructure as it pertains to writing and rhetoric. This introduction frames the value of infrastructure as a metaphor for making visible how writing and rhetoric structure and enact much of our world, especially for writing pedagogy. In addition, this article concludes by introducing the six contributions in this issue.

Quantum Algorithm For Variant Maximum Satisfiability, Abdirahman Alasow, Peter Jin, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

In this paper, we proposed a novel quantum algorithm for the maximum satisfiability problem. Satisfiability (SAT) is to find the set of assignment values of input variables for the given Boolean function that evaluates this function as TRUE or prove that such satisfying values do not exist. For a POS SAT problem, we proposed a novel quantum algorithm for the maximum satisfiability (MAX-SAT), which returns the maximum number of OR terms that are satisfied for the SAT-unsatisfiable function, providing us with information on how far the given Boolean function is from the SAT satisfaction. We used Grover’s algorithm with a …

Multi-Tasking Memcapacitive Networks, Dat Tran, Christof Teuscher

Electrical and Computer Engineering Faculty Publications and Presentations

Recent studies have shown that networks of memcapacitive devices provide an ideal computing platform of low power consumption for reservoir computing systems. Random, crossbar, or small-world power-law (SWPL) structures are common topologies for reservoir substrates to compute single tasks. However, neurological studies have shown that the interconnections of cortical brain regions associated with different functions form a rich-club structure. This structure allows human brains to perform multiple activities simultaneously. So far, memcapacitive reservoirs can perform only single tasks. Here, we propose, for the first time, cluster networks functioning as memcapacitive reservoirs to perform multiple tasks simultaneously. Our results illustrate that …

Cascadia Subduction Zone Earthquake Vertical Ground Acceleration Investigation And Potential Impact On Bridges In The Pacific Northwest, Rachel Caroline Bassil

Civil and Environmental Engineering Master's Project Reports

The effects of vertical ground accelerations during subduction zone earthquakes currently are not sufficiently understood. There are numerous case studies and evidence that effects of vertical ground accelerations can significantly impact the performance of bridges during a seismic event, but most previous research has been focused on shallow crustal earthquakes. Current bridge design codes provide little guidance for accounting for vertical ground accelerations in seismic design, in part because additional information is needed about the characteristics of vertical ground motions during Cascadia Subduction Zone (CSZ) earthquakes in the Pacific Northwest.

For this study, recorded seismic data from recent subduction zone …