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Articles 60241 - 60270 of 294411

Full-Text Articles in Physical Sciences and Mathematics

Social Capital And Cross-Boundary Collaboration In Wyoming Wildfire Management Networks, Hannah L. Spencer, Christian Heisler May 2022

Social Capital And Cross-Boundary Collaboration In Wyoming Wildfire Management Networks, Hannah L. Spencer, Christian Heisler

Student Research Symposium

Wildfire hotspots often intersect jurisdictional boundaries, so protecting human communities and restoring healthy fire regimes will require collaborative, cross-boundary action from fire managers. However, collaboration between fire management groups can have varied outcomes depending on the actors involved, all with different missions, financial obligations, and cultures. One way to conceptualize the interactions between actors is with the idea of social capital. We will investigate the following research question: how does social capital impact cross-boundary collaboration in wildfire management networks? We will survey wildfire managers in northwestern Wyoming about their collaborative actions using a snowball sampling method. Using Social Network Analysis …

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Comparison Of Heavy Metals In Spinach Grown On The Roof Ground Location At Portland State University, Tyler A. Robin May 2022

Comparison Of Heavy Metals In Spinach Grown On The Roof Ground Location At Portland State University, Tyler A. Robin

Student Research Symposium

As a result of urbanization, fresh, healthy food can be expensive and easily contaminated but space for local farming is limited. Roofs can be underutilized in densely populated cities and can offer a space for local fresh farming. The purpose of this study is to continue a previous study done in 2021, to find if growing leafy vegetables on the roof can limit heavy metal exposure from air pollutants. This study compares spinach grown on the roof in 2021, 2019 and spinach bought from stores around the Portland State University campus and the heavy metals found in these greens. The …

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Surface Plasmon Characterization In Ag Nanotriangles For Evaluation Of Fano Resonance Conditions, Nabila Islam May 2022

Surface Plasmon Characterization In Ag Nanotriangles For Evaluation Of Fano Resonance Conditions, Nabila Islam

Student Research Symposium

Surface plasmon polariton (SPP) is a collective oscillation of electrons and light at the metal -dielectric interface excited by the incident radiation on metal surface through the momentum matching conditions. The properties of SPPs and the resonance conditions are highly dependent on the confining materials and geometry of the confining nanostructure. The sensitivity of the surface plasmon resonance to the property of the confining materials made Surface plasmon resonance (SPR) sensors a central tool for biosensing. However, the frequency resolution of SPR sensors is typically limited by the broad resonance of the SPR mode. The resolution can be enhanced through …

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Growing Reservoir Networks Using The Genetic Algorithm Deep Hyperneat, Nancy L. Mackenzie May 2022

Growing Reservoir Networks Using The Genetic Algorithm Deep Hyperneat, Nancy L. Mackenzie

Student Research Symposium

Typical Artificial Neural Networks (ANNs) have static architectures. The number of nodes and their organization must be chosen and tuned for each task. Choosing these values, or hyperparameters, is a bit of a guessing game, and optimizing must be repeated for each task. If the model is larger than necessary, this leads to more training time and computational cost. The goal of this project is to evolve networks that grow according to the task at hand. By gradually increasing the size and complexity of the network to the extent that the task requires, we will build networks that are more …

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Mapping Ecosystem Service Flows Of Estuary Restoration Projects On The Oregon Coast To Identify Impacted Stakeholders, Shersten Finley May 2022

Mapping Ecosystem Service Flows Of Estuary Restoration Projects On The Oregon Coast To Identify Impacted Stakeholders, Shersten Finley

Student Research Symposium

Restoration of largely depleted estuarine systems is increasingly recognized as key to solving a variety of problems coastal communities face currently. Many of these issues will become more acute with climate change and sea level rise. Historic losses of estuary area, and recognition of the ecosystem services provided by functioning estuary ecosystems have resulted in current impetus to pursue estuary restoration. By mapping the flows of ecosystem services using three ecosystem service ‘scorecard’ categories pertaining to coastal resource management: recreation, aesthetics, and cultural/historical/spiritual, we gain a better understanding of the populations impacted by the changes in flows of ecosystem service …

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Simple Arenes As Aryne Synthetic Equivalents Via Sulfonium Salt Intermediates, Riley A. Roberts May 2022

Simple Arenes As Aryne Synthetic Equivalents Via Sulfonium Salt Intermediates, Riley A. Roberts

Student Research Symposium

Arynes are ephemeral molecules that are yet to be fully exploited in synthetic strategy because they are often challenging to access. These reactive intermediates participate in a myriad of reactions that conventional chemistry is incapable of, making them extremely useful for the synthesis of important molecules like pharmaceuticals and agrochemicals. While classical approaches for synthesizing arynes employ cheap starting material, extremely harsh reagents are necessary to generate the aryne. In contrast, methods that do not require harsh reaction conditions do require starting material that is exceedingly difficult to synthesize. To access arynes quickly and efficiently, the work described herein aims …

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Using Digital Holographic Microscopy To Characterize Vibrio's Chemotaxis, Jacqueline Acres, Eric Valentino May 2022

Using Digital Holographic Microscopy To Characterize Vibrio's Chemotaxis, Jacqueline Acres, Eric Valentino

Student Research Symposium

Vibrio alginolyticus is a marine bacterium that displays distinctive chemotactic behavior. Chemotaxis is the ability to move in response to a concentration gradient, either in the direction of nutrients or away from repellants. Vibrio's single, polar flagellum allows it to form a tight cloud in the presence of a chemoattractant. In this work, we experimentally characterize cloud sizes after both normal culture conditions and simulated microgravity using digital holographic microscopy or DHM. DHM allows visualization of volumetric samples by recording x,y,z and t information in holograms. Plane-by-plane reconstruction retrieves the z-plane information which can then by stitched together into hyperstacks …

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The Power Of The Collective: A Multi Agent-Based Modeling Approach To Nuclear Radiation Localization, Benjamin Totten, Christof Teuscher May 2022

The Power Of The Collective: A Multi Agent-Based Modeling Approach To Nuclear Radiation Localization, Benjamin Totten, Christof Teuscher

Student Research Symposium

Gamma radiation is a very high frequency, very dangerous electromagnetic wave that has a chance of being emitted after radioactive decay. Radiation source localization, or locating the previously unknown source of nuclear radiation, in a rapid and efficient manner is critically important, but challenging. We aim to create an architecture for multiple, fully independent agents that cooperate to localize sources faster than existing single-agent architectures, without compromising accuracy. Using Agent-Based Modeling and Deep Reinforcement Learning, agents are enabled to make decisions based on other agents' behaviors while maintaining programmatic autonomy. We hypothesize that radiation sources can be localized faster using …

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Research Proposal For An Assessment Of The Potential For The Arbuscular Fungi “Rhizophagus Irregularis” To Aid In Corn Uptake And Availability Of Iron, Caitlin Costello May 2022

Research Proposal For An Assessment Of The Potential For The Arbuscular Fungi “Rhizophagus Irregularis” To Aid In Corn Uptake And Availability Of Iron, Caitlin Costello

Student Research Symposium

Global iron deficiency is one factor contributing to malnutrition and varied health conditions. This deficiency accounts for 841,000 deaths and approximately 35,057,000 “disability-adjusted life years lost” (Stoltzfus, R. J. 2003). One way to combat this is to maintain or increase the iron uptake of the globe’s major crops. Research has shown that certain types of mycorrhizal fungi can increase the nutrient uptake of plants. To further this research, we will look at the arbuscular fungi Rhizophagus irregularis and its potential relationship with a short harvest corn variety. This type of mycorrhizal fungi improves plant nutrition including the plant’s ability to …

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Houseless Water Insecurity During Covid-19 Pandemic, Alicia N. Gamble May 2022

Houseless Water Insecurity During Covid-19 Pandemic, Alicia N. Gamble

Student Research Symposium

Water security is of the utmost importance for the houseless population. However, little is known about how the houseless population has been resilient to water barriers related to the COVID-19 pandemic. The purpose of this study is to understand houseless individuals' perceptions of public versus grassroots water sources, and the barriers and impacts of these sources. In order to understand these perceptions, individuals experiencing houselessness (e.g. living in tents, vehicles, emergency shelters, couch-surfing, or no roof) that utilize water sources in Portland, Oregon will be interviewed while walking in public areas to gain rich qualitative data, along with GPS data …

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Computational Investigation Of The Mechanism Of An Octahedral Ni(Ii) Proton Reduction Catalyst And Importance Of Intramolecular Hydrogen Bonding, Avik Bhattacharjee, Dayalis S.V. Brown, Carolyn N. Virca, Trent E. Ethridge, Oreana Mendez Galue, Uyen T. Pham, Theresa M. Mccormick May 2022

Computational Investigation Of The Mechanism Of An Octahedral Ni(Ii) Proton Reduction Catalyst And Importance Of Intramolecular Hydrogen Bonding, Avik Bhattacharjee, Dayalis S.V. Brown, Carolyn N. Virca, Trent E. Ethridge, Oreana Mendez Galue, Uyen T. Pham, Theresa M. Mccormick

Student Research Symposium

Water-splitting to make hydrogen gas is of extreme importance in the field of alternative energy research. Transition-metal complexes are capable of catalyzing the conversion of water to hydrogen at higher pH, with low overpotential. Our research focuses on the importance of intramolecular hydrogen bonding (H-bonding) on the pKa and thermodynamic stability of the catalytic intermediates of a well-known proton-reduction catalyst, nickel (II) tris-pyridinethiolate. Density Functional Theory (DFT) calculations on the parent catalyst and eleven derivatives demonstrate geometric isomer formation after the protonation step of catalysis. These isomers differ in the relative thermodynamic stabilities and pKa values, which can be attributed …

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Stakeholder Perceptions Of Microplastics Management In Oregon, Maya A. Hurst-Mayr May 2022

Stakeholder Perceptions Of Microplastics Management In Oregon, Maya A. Hurst-Mayr

Student Research Symposium

There is currently no federal policy in the United States that specifically addresses microplastics (MPs) pollution. However, states are beginning to act on this issue; California’s SB 1422 initiates measurement of MPs in drinking water resources and Senate Bill 1263 requires the state to adopt a strategy to reduce the ecological impact of MPs in marine ecosystems. Other West Coast states like Oregon and Washington are expected to follow California’s example. It is important to know what the actors who are a part of shaping MPs policy in Oregon would see as barriers and opportunities to doing so. We conducted …

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Analysis Of Aftershock Parameters For The Alaskan Subduction Zone Tectonic Region, Gabrielle M. Paris (They/Them), Richard C. Hugo, Andrew J. Michael May 2022

Analysis Of Aftershock Parameters For The Alaskan Subduction Zone Tectonic Region, Gabrielle M. Paris (They/Them), Richard C. Hugo, Andrew J. Michael

Student Research Symposium

On 29 July 2021, a magnitude 8.2 earthquake was felt by over 200 people near Perryville, Alaska. The early aftershock forecasts issued by the USGS use default parameters based on expected productivity within a given tectonic region. These forecasts predicted a slower decrease in aftershock activity than what was observed. Even after the USGS adjusted the aftershock forecast parameters, the forecasts did not improve in the long term. Accurate aftershock predictions are important for maintaining public confidence in disaster alert systems. The question I want to explore is: are the generic parameters used in aftershock forecasting accurately describing the observed …

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The Open-Ocean Gulf Of Mexico After Deepwater Horizon: Synthesis Of A Decade Of Research, Tracey Sutton, Rosanna J. Milligan, Kendra Daly, Kevin M. Boswell, April B. Cook, Maëlle Cornic, Tamara Frank, Kaitlin Frasier, Daniel Hahn, Frank Hernandez, John Hildebrand, Chuanmin Hu, Matthew Johnston, Samantha B. Joye, Heather Judkins, Jon A. Moore, Steven A. Murawski, Nina Pruzinsky, John A. Quinlan, Andrew Remsen, Kelly L. Robinson, Isabel C. Romero, Jay R. Rooker, Michael Vecchione, R. J. David Wells May 2022

The Open-Ocean Gulf Of Mexico After Deepwater Horizon: Synthesis Of A Decade Of Research, Tracey Sutton, Rosanna J. Milligan, Kendra Daly, Kevin M. Boswell, April B. Cook, Maëlle Cornic, Tamara Frank, Kaitlin Frasier, Daniel Hahn, Frank Hernandez, John Hildebrand, Chuanmin Hu, Matthew Johnston, Samantha B. Joye, Heather Judkins, Jon A. Moore, Steven A. Murawski, Nina Pruzinsky, John A. Quinlan, Andrew Remsen, Kelly L. Robinson, Isabel C. Romero, Jay R. Rooker, Michael Vecchione, R. J. David Wells

Marine & Environmental Sciences Faculty Articles

The scale of the Deepwater Horizon disaster was and is unprecedented: geographic extent, pollutant amount, countermeasure scope, and of most relevance to this Research Topic issue, range of ecotypes affected. These ecotypes include coastal/nearshore, continental shelf, deep benthic, and open-ocean domains, the last of which is the subject of this synthesis. The open-ocean ecotype comprises ~90% of the volume of the Gulf of Mexico. The exact percentage of this ecotype contaminated with toxins is unknown due to its three-dimensional nature and dynamics, but estimates suggest that the footprint encompassed most of its eastern half. Further, interactions between the water column …

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The Use Of Time-Lapse And Still Photographs To Document The Effects Of Seasonality On Dune Morphodynamic Evolution In Corolla, Nc., Briar Ownby-Connolly May 2022

The Use Of Time-Lapse And Still Photographs To Document The Effects Of Seasonality On Dune Morphodynamic Evolution In Corolla, Nc., Briar Ownby-Connolly

Honors Theses

With climate change altering established seasonal and weather phenomena, understanding the physical behavior of barrier islands and the processes driving such physical changes, specifically within their dune zones, is crucial in promoting their resiliency. With ecosystem services provided by dunes to coastal economies and wildlife habitat, promoting dune conservation serves to advance the benefits of these systems, within a changing climate. Current findings by the Army Corps of Engineers Field Research Facility in Duck, NC, suggest the significance of local aeolian sediment transport in interplay with storm intensity in effecting dune stability, and that anthropogenic impacts, like the installment of …

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Into The Depths: Climate Change Part 4, Felicia Bedford May 2022

Into The Depths: Climate Change Part 4, Felicia Bedford

D.U.Quark

No abstract provided.

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Network Specialization: A Topological Mechanism For The Emergence Of Cluster Synchronization, Ethan Walker May 2022

Network Specialization: A Topological Mechanism For The Emergence Of Cluster Synchronization, Ethan Walker

Theses and Dissertations

Real-world networks are dynamic in that both the state of the network components and the structure of the network (topology) change over time. Most studies regarding network evolution consider either one or the other of these types of network processes. Here we consider the interplay of the two, specifically, we consider how changes in network structure effect the dynamics of the network components. To model the growth of a network we use the specialization model known to produce many of the well-known features observed in real-world networks. We show that specialization results in a nontrivial equitable partition of the network …

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Unusual High-Frequency Mechanical Properties Of Polymer-Grafted Nanoparticle Melts, Mayank Jhalaria, Yu Chang, Yucheng Huang, Brian C. Benicewicz, Sanat K. Kumar, George Fytas May 2022

Unusual High-Frequency Mechanical Properties Of Polymer-Grafted Nanoparticle Melts, Mayank Jhalaria, Yu Chang, Yucheng Huang, Brian C. Benicewicz, Sanat K. Kumar, George Fytas

Faculty Publications

Brillouin light spectroscopy is used to measure the elastic moduli of spherical polymer-grafted nanoparticle (GNP) melts as a function of chain length at fixed grafting density (0.47  chains/nm2) and nanoparticle radius (8 nm). While the moduli follow a rule of mixtures (Wood’s law) for long chains, they display enhanced elasticity and anomalous dissipation for graft chains <1⁢0⁢0  kDa. GNP melts with long polymers at high 𝜎 have a dry zone near the GNP core, surrounded by a region where the grafts can interpenetrate with chain fragments from adjacent GNPs. We propose that the departures from Wood’s law for short chains are due to the effectively larger silica volume fraction in the region where sound propagates—this is caused by the short, interpenetrated chain fragments being pushed out of the way. We thus conclude that transport mechanisms (of gas, ions, sound, thermal phonons) in GNP melts are radically different if interpenetrated chain segments can be “pushed out of the way” or not. This provides a facile new means for manipulating the properties of these materials.

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Silver Bow Creek/Butte Area Npl Site Butte Priority Soils Operable Unit, Pioneer Technical Services, Inc. May 2022

Silver Bow Creek/Butte Area Npl Site Butte Priority Soils Operable Unit, Pioneer Technical Services, Inc.

Silver Bow Creek/Butte Area Superfund Site

No abstract provided.

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Silver Bow Creek/Butte Area Npl Site Butte Priority Soils Operable Unit, Pioneer Technical Services, Inc. May 2022

Silver Bow Creek/Butte Area Npl Site Butte Priority Soils Operable Unit, Pioneer Technical Services, Inc.

Silver Bow Creek/Butte Area Superfund Site

No abstract provided.

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2022 Residential Metals Abatement Program (Rmap) Field Sampling Plan (Fsp) – Indoor Dust – Group 3 - Butte High School/Annex, Elsie King, Christopher Berg, Thomas J. Beckman May 2022

2022 Residential Metals Abatement Program (Rmap) Field Sampling Plan (Fsp) – Indoor Dust – Group 3 - Butte High School/Annex, Elsie King, Christopher Berg, Thomas J. Beckman

Silver Bow Creek/Butte Area Superfund Site

No abstract provided.

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2022 Residential Metals Abatement Program (Rmap) Field Sampling Plan (Fsp) – Indoor Dust – Group 7 East Middle School, Elsie King, Christopher Berg, Thomas J. Beckman May 2022

2022 Residential Metals Abatement Program (Rmap) Field Sampling Plan (Fsp) – Indoor Dust – Group 7 East Middle School, Elsie King, Christopher Berg, Thomas J. Beckman

Silver Bow Creek/Butte Area Superfund Site

No abstract provided.

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Public Health Impacts Of The Clothing Industry, Schafer Flowerday May 2022

Public Health Impacts Of The Clothing Industry, Schafer Flowerday

Department of Environmental Studies: Undergraduate Student Theses

The clothing industry is worth $1.5 trillion dollars and rapidly expanding (Statista, 2021). The industry is dominated by fast fashion, which accounts for clothing that is quickly and cheaply produced, based on ever-changing trends. 90% of textiles produced are made in low-income countries, predominantly in South Asia (Seigel, 2011). This systematic literature review looks into the impact this industry has on these vulnerable populations which are working and living in areas where clothing is produced. Environmental and Occupational health hazards and impacts were researched. Environmental impacts occur at each step of the process. Polyester is the most common textile, and …

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Generating A Dataset For Comparing Linear Vs. Non-Linear Prediction Methods In Education Research, Jack Mauro, Elena Martinez, Anna Bargagliotti May 2022

Generating A Dataset For Comparing Linear Vs. Non-Linear Prediction Methods In Education Research, Jack Mauro, Elena Martinez, Anna Bargagliotti

Honors Thesis

Machine learning is often used to build predictive models by extracting patterns from large data sets. Such techniques are increasingly being utilized to predict outcomes in the social sciences. One such application is predicting student success. Machine learning can be applied to predicting student acceptance and success in academia. Using these tools for education-related data analysis, may enable the evaluation of programs, resources and curriculum. Currently, research is needed to examine application, admissions, and retention data in order to address equity in college computer science programs. However, most student-level data sets contain sensitive data that cannot be made public. To …

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Computational And Spectroscopic Studies Of New Sulfur-Containing Dipole-Bound Anions, Nicholas Allen Kruse May 2022

Computational And Spectroscopic Studies Of New Sulfur-Containing Dipole-Bound Anions, Nicholas Allen Kruse

Honors Theses

Sulfur and Nitrogen are essential ingredients in both life-supporting and light-harvesting molecules. Their presence also usually leads to the delocalization of electrons and large dipole and quadrupole moments. Such molecules are sometimes able to form negative ions through the electrostatic binding of an excess electron. These so-called multipole-bound (dipole-bound, quadrupole-bound, etc.) anions have been shown to be important in radiation damage in biology and electron transport processes. Here, we present our recent computational and experimental results studying the creation of new multipole-bound anions.

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Stabilization Of Phenanthrene Anions In Helium Nanodroplets, Siegfried Kollotzek, Farhad Izadi, Miriam Meyer, Stefan Bergmeister, Fabio Zappa, Stephan Denifl, Olof E. Echt, Paul Scheier, Elisabeth Gruber May 2022

Stabilization Of Phenanthrene Anions In Helium Nanodroplets, Siegfried Kollotzek, Farhad Izadi, Miriam Meyer, Stefan Bergmeister, Fabio Zappa, Stephan Denifl, Olof E. Echt, Paul Scheier, Elisabeth Gruber

Faculty Publications

It has been debated for years if the polycyclic aromatic hydrocarbon phenanthrene exists in its anionic form, or, in other words, if its electron affinity (EA) is positive or negative. In this contribution we confirm that the bare phenanthrene anion Ph- created in a binary collision with an electron at room temperature has a lifetime shorter than microseconds. However, the embedding of neutral phenanthrene molecules in negatively charged helium nanodroplets enables the formation of phenanthrene anions by charge transfer processes and the stabilization of the latter in the ultracold environment. Gentle shrinking of the helium matrix of phenanthrene-doped HNDs …

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2022 Residential Metals Abatement Program (Rmap) Field Sampling Plan (Fsp) – Indoor Dust – Group 2 West Elementary, Elsie King, Christopher Berg, Thomas J. Beckman May 2022

2022 Residential Metals Abatement Program (Rmap) Field Sampling Plan (Fsp) – Indoor Dust – Group 2 West Elementary, Elsie King, Christopher Berg, Thomas J. Beckman

Silver Bow Creek/Butte Area Superfund Site

No abstract provided.

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A Few-Shot Learning Model Based On A Triplet Network For The Prediction Of Energy Coincident Peak Days, Jinxiang Liu, Laura Brown May 2022

A Few-Shot Learning Model Based On A Triplet Network For The Prediction Of Energy Coincident Peak Days, Jinxiang Liu, Laura Brown

Michigan Tech Publications, Part 1

In an electricity system, a coincident peak (CP) is defined as the highest daily power demand in a year, which plays an important role in keeping the balance between power supply and its demand. Advanced information about the time of coincident peaks would be helpful for both utility companies and their customers. This work addresses the prediction of the five coincident peak days (5CP) in a year. We present a few-shot learning model to classify a day as a 5CP day or a non-5CP day 24-hours ahead. A triplet network is implemented for the 2-way-5-shot classifications on six different historical …

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Discussion Of “Guiding Principles For Hydrologists Conducting Interdisciplinary Research And Fieldwork With Participants”, Melissa Haeffner May 2022

Discussion Of “Guiding Principles For Hydrologists Conducting Interdisciplinary Research And Fieldwork With Participants”, Melissa Haeffner

Environmental Science and Management Faculty Publications and Presentations

Rangecroft et al. (2021) offer a set of principles for conducting interdisciplinary research and fieldwork with participants from a hydrologist perspective. In this invited paper, I present some thoughts from a social scientist’s perspective, not to disagree with their points but to add to them. Specifically, I use my sociology background and interdisciplinary experiences to reflect on qualitative evaluative criteria, power dynamics in the scientific community, barriers to interdisciplinary research, and approaches to overcome obstacles. Individual researchers can educate themselves about other disciplines, and there are also opportunities for institutional change on the part of universities, funders, and …

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Evolution Of Combined Arms Tactics In Heterogeneous Multi-Agent Teams, Robert J. Wilson, David W. King, Gilbert L. Peterson May 2022

Evolution Of Combined Arms Tactics In Heterogeneous Multi-Agent Teams, Robert J. Wilson, David W. King, Gilbert L. Peterson

Faculty Publications

Multi-agent systems research is concerned with the emergence of system-level behaviors from relatively simple agent interactions. Multi-agent systems research to date is primarily concerned with systems of homogeneous agents, with member agents both physically and behaviorally identical. Systems of heterogeneous agents with differing physical or behavioral characteristics may be able to accomplish tasks more efficiently than homogeneous teams, via cooperation between mutually complementary agent types. In this article, we compare the performance of homogeneous and heterogeneous teams in combined arms situations. Combined arms theory proposes that the application of heterogeneous forces, en masse, can generate effects far greater than outcomes …

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