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Full-Text Articles in Physical Sciences and Mathematics

Evaluation Of Daily Precipitation From The Era5 Global Reanalysis Against Ghcn Observations In The Northeastern United States, Caitlin C. Crossett, Alan K. Betts, Lesley Ann L. Dupigny-Giroux, Arne Bomblies Dec 2020

Evaluation Of Daily Precipitation From The Era5 Global Reanalysis Against Ghcn Observations In The Northeastern United States, Caitlin C. Crossett, Alan K. Betts, Lesley Ann L. Dupigny-Giroux, Arne Bomblies

College of Engineering and Mathematical Sciences Faculty Publications

Licensee MDPI, Basel, Switzerland. Precipitation is a primary input for hydrologic, agricultural, and engineering models, so making accurate estimates of it across the landscape is critically important. While the distribution of in-situ measurements of precipitation can lead to challenges in spatial interpolation, gridded precipitation information is designed to produce a full coverage product. In this study, we compare daily precipitation accumulations from the ERA5 Global Reanalysis (hereafter ERA5) and the US Global Historical Climate Network (hereafter GHCN) across the northeastern United States. We find that both the distance from the Atlantic Coast and elevation difference between ERA5 estimates and GHCN …


Modeling The Influence Of Public Risk Perceptions On The Adoption Of Green Stormwater Infrastructure: An Application Of Bayesian Belief Networks Versus Logistic Regressions On A Statewide Survey Of Households In Vermont, Qing Ren, Asim Zia, Donna M. Rizzo, Nancy Mathews Oct 2020

Modeling The Influence Of Public Risk Perceptions On The Adoption Of Green Stormwater Infrastructure: An Application Of Bayesian Belief Networks Versus Logistic Regressions On A Statewide Survey Of Households In Vermont, Qing Ren, Asim Zia, Donna M. Rizzo, Nancy Mathews

College of Engineering and Mathematical Sciences Faculty Publications

There is growing environmental psychology and behavior literature with mixed empirical evidence about the influence of public risk perceptions on the adoption of environmentally friendly “green behaviors”. Adoption of stormwater green infrastructure on residential properties, while costlier in the short term compared to conventional greywater infrastructure, plays an important role in the reduction of nutrient loading from non-point sources into freshwater rivers and lakes. In this study, we use Bayesian Belief Networks (BBNs) to analyze a 2015 survey dataset (sample size = 472 respondents) about the adoption of green infrastructure (GSI) in Vermont’s residential areas, most of which are located …


Temperature Controls Production But Hydrology Regulates Export Of Dissolved Organic Carbon At The Catchment Scale, Hang Wen, Julia Perdrial, Benjamin W. Abbott, Susana Bernal, Remi Dupas, Sarah E. Godsey, Adrian Harpold, Donna Rizzo, Kristen Underwood, Thomas Adler, Gary Sterle, Li Li Feb 2020

Temperature Controls Production But Hydrology Regulates Export Of Dissolved Organic Carbon At The Catchment Scale, Hang Wen, Julia Perdrial, Benjamin W. Abbott, Susana Bernal, Remi Dupas, Sarah E. Godsey, Adrian Harpold, Donna Rizzo, Kristen Underwood, Thomas Adler, Gary Sterle, Li Li

College of Engineering and Mathematical Sciences Faculty Publications

Lateral carbon flux through river networks is an important and poorly understood component of the global carbon budget. This work investigates how temperature and hydrology control the production and export of dissolved organic carbon (DOC) in the Susquehanna Shale Hills Critical Zone Observatory in Pennsylvania, USA. Using field measurements of daily stream discharge, evapotranspiration, and stream DOC concentration, we calibrated the catchment-scale biogeochemical reactive transport model BioRT-Flux-PIHM (Biogeochemical Reactive Transport-Flux-Penn State Integrated Hydrologic Model, BFP), which met the satisfactory standard of a Nash-Sutcliffe efficiency (NSE) value greater than 0.5. We used the calibrated model to estimate and compare the daily …


Noncooperative Dynamics In Election Interference, David Rushing Dewhurst, Christopher M. Danforth, Peter Sheridan Dodds Feb 2020

Noncooperative Dynamics In Election Interference, David Rushing Dewhurst, Christopher M. Danforth, Peter Sheridan Dodds

College of Engineering and Mathematical Sciences Faculty Publications

Foreign power interference in domestic elections is an existential threat to societies. Manifested through myriad methods from war to words, such interference is a timely example of strategic interaction between economic and political agents. We model this interaction between rational game players as a continuous-time differential game, constructing an analytical model of this competition with a variety of payoff structures. All-or-nothing attitudes by only one player regarding the outcome of the game lead to an arms race in which both countries spend increasing amounts on interference and counterinterference operations. We then confront our model with data pertaining to the Russian …


Upcycling Phosphorus Recovered From Anaerobically Digested Dairy Manure To Support Production Of Vegetables And Flowers, Katherine K. Porterfield, Robert Joblin, Deborah A. Neher, Michael Curtis, Steve Dvorak, Donna M. Rizzo, Joshua W. Faulkner, Eric D. Roy Feb 2020

Upcycling Phosphorus Recovered From Anaerobically Digested Dairy Manure To Support Production Of Vegetables And Flowers, Katherine K. Porterfield, Robert Joblin, Deborah A. Neher, Michael Curtis, Steve Dvorak, Donna M. Rizzo, Joshua W. Faulkner, Eric D. Roy

College of Engineering and Mathematical Sciences Faculty Publications

Dissolved air flotation (DAF) separates phosphorus (P)-rich fine solids from anaerobically digested dairy manure, creating opportunities to export surplus P to the marketplace as a bagged plant food product. Seedlings of tomato and marigold were amended at various volume per volume (v/v) ratios with plant foods consisting of fine solids upcycled (i.e., transformed into a higher quality product) by drying and blending with other organic residuals. A plate competition assay was conducted to assess the fine solids' potential to suppress the plant pathogen Rhizoctonia solani. Plant foods were comprised of 2.0-2.1% N, 0.8-0.9% P and 0.6-0.8% K. Extractions indicated that …


Fragmentation And Inefficiencies In Us Equity Markets: Evidence From The Dow 30, Brian F. Tivnan, David Rushing Dewhurst, Colin M. Van Oort, John H. Ring, Tyler J. Gray, Brendan F. Tivnan, Matthew T.K. Koehler, Matthew T. Mcmahon, David M. Slater, Jason G. Veneman, Christopher M. Danforth Jan 2020

Fragmentation And Inefficiencies In Us Equity Markets: Evidence From The Dow 30, Brian F. Tivnan, David Rushing Dewhurst, Colin M. Van Oort, John H. Ring, Tyler J. Gray, Brendan F. Tivnan, Matthew T.K. Koehler, Matthew T. Mcmahon, David M. Slater, Jason G. Veneman, Christopher M. Danforth

College of Engineering and Mathematical Sciences Faculty Publications

Using the most comprehensive source of commercially available data on the US National Market System, we analyze all quotes and trades associated with Dow 30 stocks in calendar year 2016 from the vantage point of a single and fixed frame of reference. We find that inefficiencies created in part by the fragmentation of the equity marketplace are relatively common and persist for longer than what physical constraints may suggest. Information feeds reported different prices for the same equity more than 120 million times, with almost 64 million dislocation segments featuring meaningfully longer duration and higher magnitude. During this period, roughly …


Electricity Rates For The Zero Marginal Cost Grid, Helen Lo, Seth Blumsack, Paul Hines, Sean Meyn Apr 2019

Electricity Rates For The Zero Marginal Cost Grid, Helen Lo, Seth Blumsack, Paul Hines, Sean Meyn

College of Engineering and Mathematical Sciences Faculty Publications

The electricity industry is rapidly changing: costs are increasingly dominated by capital and technology is turning loads into resources. This is similar to the early days of the Internet. Building on rate-structures used in the communications industry, utilities of the future should offer customers a portfolio of service contract options that provide a signal to the utility regarding the type and amount of infrastructure that should be deployed.


Social Media Usage Patterns During Natural Hazards, Meredith T. Niles, Benjamin F. Emery, Andrew J. Reagan, Peter Sheridan Dodds, Christopher M. Danforth Feb 2019

Social Media Usage Patterns During Natural Hazards, Meredith T. Niles, Benjamin F. Emery, Andrew J. Reagan, Peter Sheridan Dodds, Christopher M. Danforth

College of Engineering and Mathematical Sciences Faculty Publications

Natural hazards are becoming increasingly expensive as climate change and development are exposing communities to greater risks. Preparation and recovery are critical for climate change resilience, and social media are being used more and more to communicate before, during, and after disasters. While there is a growing body of research aimed at understanding how people use social media surrounding disaster events, most existing work has focused on a single disaster case study. In the present study, we analyze five of the costliest disasters in the last decade in the United States (Hurricanes Irene and Sandy, two sets of tornado outbreaks, …


Application Of Unmanned Aircraft System (Uas) For Monitoring Bank Erosion Along River Corridors, Scott D. Hamshaw, Tayler Engel, Donna M. Rizzo, Jarlath O’Neil-Dunne, Mandar M. Dewoolkar Jan 2019

Application Of Unmanned Aircraft System (Uas) For Monitoring Bank Erosion Along River Corridors, Scott D. Hamshaw, Tayler Engel, Donna M. Rizzo, Jarlath O’Neil-Dunne, Mandar M. Dewoolkar

College of Engineering and Mathematical Sciences Faculty Publications

Excessive streambank erosion is a significant source of fine sediments and associated nutrients in many river systems as well as poses risk to infrastructure. Geomorphic change detection using high-resolution topographic data is a useful method for monitoring the extent of bank erosion along river corridors. Recent advances in an unmanned aircraft system (UAS) and structure from motion (SfM) photogrammetry techniques allow acquisition of high-resolution topographic data, which are the methods used in this study. To evaluate the effectiveness of UAS-based photogrammetry for monitoring bank erosion, a fixed-wing UAS was deployed to survey 20 km of river corridors in central Vermont, …


Computational Fluid Dynamics-Based Modeling Of Liquefied Soils, S. Banerjee, J. Chen, D. L. Hitt, M. M. Dewoolkar, S. M. Olson Jan 2019

Computational Fluid Dynamics-Based Modeling Of Liquefied Soils, S. Banerjee, J. Chen, D. L. Hitt, M. M. Dewoolkar, S. M. Olson

College of Engineering and Mathematical Sciences Faculty Publications

The residual shear strength of liquefied soil is a key parameter in evaluating liquefaction flow failures. Results from a series of dynamic centrifuge experiments where the shear strength of liquefied soil was inferred by measuring the force required to pull a thin metal plate (coupon) horizontally through the liquefied soil are assessed here using a computational fluid dynamics (CFD) based model. Viscosity is a key parameter for the Newtonian fluid constitutive model used in the simulations, and apparent viscosities of liquefied soil in the range of about 5,800 – 13,300 Pa·s were obtained when the CFD model was calibrated against …


From The Household To Watershed: A Cross-Scale Analysis Of Residential Intention To Adopt Green Stormwater Infrastructure, Sarah Coleman, Stephanie Hurley, Donna Rizzo, Christopher Koliba, Asim Zia Dec 2018

From The Household To Watershed: A Cross-Scale Analysis Of Residential Intention To Adopt Green Stormwater Infrastructure, Sarah Coleman, Stephanie Hurley, Donna Rizzo, Christopher Koliba, Asim Zia

College of Engineering and Mathematical Sciences Faculty Publications

Improved stormwater management for the protection of water resources requires bottom-up stewardship from landowners, including adoption of Green Stormwater Infrastructure (GSI). We use a statewide survey of Vermont paired with a cross-scale and spatial analysis to evaluate the influence of interacting spatial, social, and physical factors on residential intention to adopt GSI across a complex social-ecological landscape. Specifically, we focus on how three GSI practices, (“rain garden (bio retention),” “infiltration trenches,” and “actively divert roof runoff to a rain barrel/lawn/garden instead of the street/sewer”) vary with barriers to adoption, and household attributes across stormwater contexts from the household to watershed …


Erratum: Reducing Cascading Failure Risk By Increasing Infrastructure Network Interdependence, Mert Korkali, Jason G. Veneman, Brian F. Tivnan, James P. Bagrow, Paul D.H. Hines Mar 2018

Erratum: Reducing Cascading Failure Risk By Increasing Infrastructure Network Interdependence, Mert Korkali, Jason G. Veneman, Brian F. Tivnan, James P. Bagrow, Paul D.H. Hines

College of Engineering and Mathematical Sciences Faculty Publications

This corrects the article DOI: 10.1038/srep44499.


Nets: Extremely Fast Outlier Detection From A Data Stream Via Set-Based Processing, Susik Yoon, Jae Gil Lee, Byung Suk Lee Jan 2018

Nets: Extremely Fast Outlier Detection From A Data Stream Via Set-Based Processing, Susik Yoon, Jae Gil Lee, Byung Suk Lee

College of Engineering and Mathematical Sciences Faculty Publications

This paper addresses the problem of efficiently detecting outliers from a data stream as old data points expire from and new data points enter the window incrementally. The proposed method is based on a newly discovered characteristic of a data stream that the change in the locations of data points in the data space is typically very insignificant. This observation has led to the finding that the existing distance-based outlier detection algorithms perform excessive unnecessary computations that are repetitive and/or canceling out the effects. Thus, in this paper, we propose a novel set-based approach to detecting outliers, whereby data points …


Energy And Complexity, Zofia Lukszo, Ettore Bompard, Paul Hines, Liz Varga Jan 2018

Energy And Complexity, Zofia Lukszo, Ettore Bompard, Paul Hines, Liz Varga

College of Engineering and Mathematical Sciences Faculty Publications

No abstract provided.


Evaluating Spatial Variability In Sediment And Phosphorus Concentration-Discharge Relationships Using Bayesian Inference And Self-Organizing Maps, Kristen L. Underwood, Donna M. Rizzo, Andrew W. Schroth, Mandar M. Dewoolkar Dec 2017

Evaluating Spatial Variability In Sediment And Phosphorus Concentration-Discharge Relationships Using Bayesian Inference And Self-Organizing Maps, Kristen L. Underwood, Donna M. Rizzo, Andrew W. Schroth, Mandar M. Dewoolkar

College of Engineering and Mathematical Sciences Faculty Publications

Given the variable biogeochemical, physical, and hydrological processes driving fluvial sediment and nutrient export, the water science and management communities need data-driven methods to identify regions prone to production and transport under variable hydrometeorological conditions. We use Bayesian analysis to segment concentration-discharge linear regression models for total suspended solids (TSS) and particulate and dissolved phosphorus (PP, DP) using 22 years of monitoring data from 18 Lake Champlain watersheds. Bayesian inference was leveraged to estimate segmented regression model parameters and identify threshold position. The identified threshold positions demonstrated a considerable range below and above the median discharge—which has been used previously …


Catastrophic Failure Of Nacre Under Pure Shear Stresses Of Torsion, Saleh Alghamdi, Ting Tan, Christopher Hale-Sills, Floyd Vilmont, Tian Xia, Jie Yang, Dryver Huston, Mandar Dewoolkar Dec 2017

Catastrophic Failure Of Nacre Under Pure Shear Stresses Of Torsion, Saleh Alghamdi, Ting Tan, Christopher Hale-Sills, Floyd Vilmont, Tian Xia, Jie Yang, Dryver Huston, Mandar Dewoolkar

College of Engineering and Mathematical Sciences Faculty Publications

Nacre, a composite made from biogenic aragonite and proteins, exhibits excellent strength and toughness. Here, we show that nacreous sections can exhibit complete brittle fracture along the tablet interfaces at the proportional limit under pure shear stresses of torsion. We quantitatively separate the initial tablet sliding primarily resisted by nanoscale aragonite pillars from the following sliding resisted by various microscale toughening mechanisms. We postulate that the ductility of nacre can be limited by eliminating tablet interactions during crack propagations. Our findings should help pursuing further insights of layered materials by using torsion.


Evaluation Of A Proposal For Reliable Low-Cost Grid Power With 100% Wind, Water, And Solar, Christopher T.M. Clack, Staffan A. Qvist, Jay Apt, Morgan Bazilian, Adam R. Brandt, Ken Caldeira, Steven J. Davis, Victor Diakov, Mark A. Handschy, Paul D.H. Hines, Paulina Jaramillo, Daniel M. Kammen, Jane C.S. Long, M. Granger Morgan, Adam Reed, Varun Sivaram, James Sweeney, George R. Tynan, David G. Victor, John P. Weyant, Jay F. Whitacre Jun 2017

Evaluation Of A Proposal For Reliable Low-Cost Grid Power With 100% Wind, Water, And Solar, Christopher T.M. Clack, Staffan A. Qvist, Jay Apt, Morgan Bazilian, Adam R. Brandt, Ken Caldeira, Steven J. Davis, Victor Diakov, Mark A. Handschy, Paul D.H. Hines, Paulina Jaramillo, Daniel M. Kammen, Jane C.S. Long, M. Granger Morgan, Adam Reed, Varun Sivaram, James Sweeney, George R. Tynan, David G. Victor, John P. Weyant, Jay F. Whitacre

College of Engineering and Mathematical Sciences Faculty Publications

A number of analyses, meta-Analyses, and assessments, including those performed by the Intergovernmental Panel on Climate Change, the National Oceanic and Atmospheric Administration, the National Renewable Energy Laboratory, and the International Energy Agency, have concluded that deployment of a diverse portfolio of clean energy technologies makes a transition to a low-carbon-emission energy system both more feasible and less costly than other pathways. In contrast, Jacobson et al. [Jacobson MZ, Delucchi MA, Cameron MA, Frew BA (2015) Proc Natl Acad Sci USA 112(49):15060-15065] argue that it is feasible to provide "low-cost solutions to the grid reliability problem with 100% penetration of …


Characterizing Landscape-Scale Erosion Using 10be In Detrital Fluvial Sediment: Slope-Based Sampling Strategy Detects The Effect Of Widespread Dams, Lucas J. Reusser, Paul R. Bierman, Donna M. Rizzo, Eric W. Portenga, Dylan H. Rood May 2017

Characterizing Landscape-Scale Erosion Using 10be In Detrital Fluvial Sediment: Slope-Based Sampling Strategy Detects The Effect Of Widespread Dams, Lucas J. Reusser, Paul R. Bierman, Donna M. Rizzo, Eric W. Portenga, Dylan H. Rood

College of Engineering and Mathematical Sciences Faculty Publications

Concentrations of in situ 10Be measured in detrital fluvial sediment are frequently used to estimate long-term erosion rates of drainage basins. In many regions, basin-averaged erosion rates are positively correlated with basin average slope. The slope dependence of erosion allows model-based erosion rate estimation for unsampled basins and basins where human disturbance may have biased cosmogenic nuclide concentrations in sediment. Using samples collected from southeastern North America, we demonstrate an approach that explicitly considers the relationship between average basin slope and erosion rate. Because dams and reservoirs are ubiquitous on larger channels in the field area, we selected 36 undammed …


Reducing Cascading Failure Risk By Increasing Infrastructure Network Interdependence, Mert Korkali, Jason G. Veneman, Brian F. Tivnan, James P. Bagrow, Paul D.H. Hines Mar 2017

Reducing Cascading Failure Risk By Increasing Infrastructure Network Interdependence, Mert Korkali, Jason G. Veneman, Brian F. Tivnan, James P. Bagrow, Paul D.H. Hines

College of Engineering and Mathematical Sciences Faculty Publications

Increased interconnection between critical infrastructure networks, such as electric power and communications systems, has important implications for infrastructure reliability and security. Others have shown that increased coupling between networks that are vulnerable to internetwork cascading failures can increase vulnerability. However, the mechanisms of cascading in these models differ from those in real systems and such models disregard new functions enabled by coupling, such as intelligent control during a cascade. This paper compares the robustness of simple topological network models to models that more accurately reflect the dynamics of cascading in a particular case of coupled infrastructures. First, we compare a …


Transitions In Climate And Energy Discourse Between Hurricanes Katrina And Sandy, Emily M. Cody, Jennie C. Stephens, James P. Bagrow, Peter Sheridan Dodds, Christopher M. Danforth Mar 2017

Transitions In Climate And Energy Discourse Between Hurricanes Katrina And Sandy, Emily M. Cody, Jennie C. Stephens, James P. Bagrow, Peter Sheridan Dodds, Christopher M. Danforth

College of Engineering and Mathematical Sciences Faculty Publications

Although climate change and energy are intricately linked, their explicit connection is not always prominent in public discourse and the media. Disruptive extreme weather events, including hurricanes, focus public attention in new and different ways offering a unique window of opportunity to analyze how a focusing event influences public discourse. Media coverage of extreme weather events simultaneously shapes and reflects public discourse on climate issues. Here, we analyze climate and energy newspaper coverage of Hurricanes Katrina (2005) and Sandy (2012) using topic models, mathematical techniques used to discover abstract topics within a set of documents. Our results demonstrate that post-Katrina …


Coupled Impacts Of Climate And Land Use Change Across A River-Lake Continuum: Insights From An Integrated Assessment Model Of Lake Champlain's Missisquoi Basin, 2000-2040, Asim Zia, Arne Bomblies, Andrew W. Schroth, Christopher Koliba, Peter D.F. Isles, Yushiou Tsai, Ibrahim N. Mohammed, Gabriela Bucini, Patrick J. Clemins, Scott Turnbull, Morgan Rodgers, Ahmed Hamed, Brian Beckage, Jonathan Winter Nov 2016

Coupled Impacts Of Climate And Land Use Change Across A River-Lake Continuum: Insights From An Integrated Assessment Model Of Lake Champlain's Missisquoi Basin, 2000-2040, Asim Zia, Arne Bomblies, Andrew W. Schroth, Christopher Koliba, Peter D.F. Isles, Yushiou Tsai, Ibrahim N. Mohammed, Gabriela Bucini, Patrick J. Clemins, Scott Turnbull, Morgan Rodgers, Ahmed Hamed, Brian Beckage, Jonathan Winter

College of Engineering and Mathematical Sciences Faculty Publications

Global climate change (GCC) is projected to bring higher-intensity precipitation and higher-variability temperature regimes to the Northeastern United States. The interactive effects of GCC with anthropogenic land use and land cover changes (LULCCs) are unknown for watershed level hydrological dynamics and nutrient fluxes to freshwater lakes. Increased nutrient fluxes can promote harmful algal blooms, also exacerbated by warmer water temperatures due to GCC. To address the complex interactions of climate, land and humans, we developed a cascading integrated assessment model to test the impacts of GCC and LULCC on the hydrological regime, water temperature, water quality, bloom duration and severity …


Surface Permeability Of Natural And Engineered Porous Building Materials, David Grover, Cabot R. Savidge, Laura Townsend, Odanis Rosario, Liang Bo Hu, Donna M. Rizzo, Mandar M. Dewoolkar Jun 2016

Surface Permeability Of Natural And Engineered Porous Building Materials, David Grover, Cabot R. Savidge, Laura Townsend, Odanis Rosario, Liang Bo Hu, Donna M. Rizzo, Mandar M. Dewoolkar

College of Engineering and Mathematical Sciences Faculty Publications

Characterization of surface gas permeability measurements on a variety of natural and engineered building materials using two relatively new, non-destructive surface permeameters is presented. Surface gas permeability measurements were consistent for both laboratory and field applications and correlated well with bulk gas permeability measurements. This research indicates that surface permeability measurements could provide reliable estimates of bulk gas permeability; and due to the non-destructive nature and relative sampling ease of both surface gas permeability tools, it is possible to quantify the range of the spatial autocorrelation, heterogeneity, and anisotropy in porous building materials and their degree of degradation from weathering.


Tracking Climate Change Through The Spatiotemporal Dynamics Of The Teletherms, The Statistically Hottest And Coldest Days Of The Year, Peter Sheridan Dodds, Lewis Mitchell, Andrew J. Reagan, Christopher M. Danforth May 2016

Tracking Climate Change Through The Spatiotemporal Dynamics Of The Teletherms, The Statistically Hottest And Coldest Days Of The Year, Peter Sheridan Dodds, Lewis Mitchell, Andrew J. Reagan, Christopher M. Danforth

College of Engineering and Mathematical Sciences Faculty Publications

Instabilities and long term shifts in seasons, whether induced by natural drivers or human activities, pose great disruptive threats to ecological, agricultural, and social systems. Here, we propose, measure, and explore two fundamental markers of location-sensitive seasonal variations: the Summer and Winter Teletherms - the on-average annual dates of the hottest and coldest days of the year. We analyse daily temperature extremes recorded at 1218 stations across the contiguous United States from 1853-2012, and observe large regional variation with the Summer Teletherm falling up to 90 days after the Summer Solstice, and 50 days for the Winter Teletherm after the …


Predicting Flow Reversals In A Computational Fluid Dynamics Simulated Thermosyphon Using Data Assimilation, Andrew J. Reagan, Yves Dubief, Peter Sheridan Dodds, Christopher M. Danforth Feb 2016

Predicting Flow Reversals In A Computational Fluid Dynamics Simulated Thermosyphon Using Data Assimilation, Andrew J. Reagan, Yves Dubief, Peter Sheridan Dodds, Christopher M. Danforth

College of Engineering and Mathematical Sciences Faculty Publications

A thermal convection loop is a annular chamber filled with water, heated on the bottom half and cooled on the top half. With sufficiently large forcing of heat, the direction of fluid flow in the loop oscillates chaotically, dynamics analogous to the Earth's weather. As is the case for state-of-the-art weather models, we only observe the statistics over a small region of state space, making prediction difficult. To overcome this challenge, data assimilation (DA) methods, and specifically ensemble methods, use the computational model itself to estimate the uncertainty of the model to optimally combine these observations into an initial condition …


If You've Seen One Worm, Have You Seen Them All? Spatial, Community, And Genetic Variability Of Tubificid Communities In Montana, Nilanjan Lodh, Donna M. Rizzo, Billie L. Kerans, Stephanie Mcginnis, Nikolaos Fytilis, Lori Stevens Sep 2015

If You've Seen One Worm, Have You Seen Them All? Spatial, Community, And Genetic Variability Of Tubificid Communities In Montana, Nilanjan Lodh, Donna M. Rizzo, Billie L. Kerans, Stephanie Mcginnis, Nikolaos Fytilis, Lori Stevens

College of Engineering and Mathematical Sciences Faculty Publications

Genetic studies are recognized increasingly as important for understanding naturally occurring disease dynamics and are used to predict host genetic diversity and coevolutionary processes and to identify species composition in ecological communities. Tubifex tubifex, the definitive host of the whirling disease parasite Myxobolus cerebralis, comprises 6 known lineages that vary widely in parasite susceptibility. We used 16S ribosomal DNA (16S rDNA) to identify relationships among genetic variability of 3 oligochaete genera (T. tubifex, Rhyacodrilus spp., and Ilyodrilus spp.; Oligochaeta:Tubificidae), oligochaete assemblage composition, and the presence of whirling disease in 9 locations across 4 watersheds in Montana, USA. We assessed genetic …


Climate Change Sentiment On Twitter: An Unsolicited Public Opinion Poll, Emily M. Cody, Andrew J. Reagan, Lewis Mitchell, Peter Sheridan Dodds, Christopher M. Danforth Aug 2015

Climate Change Sentiment On Twitter: An Unsolicited Public Opinion Poll, Emily M. Cody, Andrew J. Reagan, Lewis Mitchell, Peter Sheridan Dodds, Christopher M. Danforth

College of Engineering and Mathematical Sciences Faculty Publications

The consequences of anthropogenic climate change are extensively debated through scientific papers, newspaper articles, and blogs. Newspaper articles may lack accuracy, while the severity of findings in scientific papers may be too opaque for the public to understand. Social media, however, is a forum where individuals of diverse backgrounds can share their thoughts and opinions. As consumption shifts from old media to new, Twitter has become a valuable resource for analyzing current events and headline news. In this research, we analyze tweets containing the word "climate" collected between September 2008 and July 2014. Through use of a previously developed sentiment …


Robustness Of Spatial Micronetworks, Thomas C. Mcandrew, Christopher M. Danforth, James P. Bagrow Apr 2015

Robustness Of Spatial Micronetworks, Thomas C. Mcandrew, Christopher M. Danforth, James P. Bagrow

College of Engineering and Mathematical Sciences Faculty Publications

Power lines, roadways, pipelines, and other physical infrastructure are critical to modern society. These structures may be viewed as spatial networks where geographic distances play a role in the functionality and construction cost of links. Traditionally, studies of network robustness have primarily considered the connectedness of large, random networks. Yet for spatial infrastructure, physical distances must also play a role in network robustness. Understanding the robustness of small spatial networks is particularly important with the increasing interest in microgrids, i.e., small-area distributed power grids that are well suited to using renewable energy resources. We study the random failures of links …


Characterization Of Increased Persistence And Intensity Of Precipitation In The Northeastern United States, Justin Guilbert, Alan K. Betts, Donna M. Rizzo, Brian Beckage, Arne Bomblies Jan 2015

Characterization Of Increased Persistence And Intensity Of Precipitation In The Northeastern United States, Justin Guilbert, Alan K. Betts, Donna M. Rizzo, Brian Beckage, Arne Bomblies

College of Engineering and Mathematical Sciences Faculty Publications

We present evidence of increasing persistence in daily precipitation in the northeastern United States that suggests that global circulation changes are affecting regional precipitation patterns. Meteorological data from 222 stations in 10 northeastern states are analyzed using Markov chain parameter estimates to demonstrate that a significant mode of precipitation variability is the persistence of precipitation events. We find that the largest region‐wide trend in wet persistence (i.e., the probability of precipitation in 1 day and given precipitation in the preceding day) occurs in June (+0.9% probability per decade over all stations). We also find that the study region is experiencing …


Acoustic Streaming, Fluid Mixing, And Particle Transport By A Gaussian Ultrasound Beam In A Cylindrical Container, Jeffrey S. Marshall, Junru Wu Jan 2015

Acoustic Streaming, Fluid Mixing, And Particle Transport By A Gaussian Ultrasound Beam In A Cylindrical Container, Jeffrey S. Marshall, Junru Wu

College of Engineering and Mathematical Sciences Faculty Publications

A computational study is reported of the acoustic streaming flow field generated by a Gaussian ultrasound beam propagating normally toward the end wall of a cylindrical container. Particular focus is given to examining the effectiveness of the acoustic streaming flow for fluid mixing within the container, for deposition of particles in suspension onto the bottom surface, and for particle suspension from the bottom surface back into the flow field. The flow field is assumed to be axisymmetric with the ultrasound transducer oriented parallel to the cylinder axis and normal to the bottom surface of the container, which we refer to …


Analysis Of A Consumer Survey On Plug-In Hybrid Electric Vehicles, Joseph S. Krupa, Donna M. Rizzo, Margaret J. Eppstein, D. Brad Lanute, Diann E. Gaalema, Kiran Lakkaraju, Christina E. Warrender Jan 2014

Analysis Of A Consumer Survey On Plug-In Hybrid Electric Vehicles, Joseph S. Krupa, Donna M. Rizzo, Margaret J. Eppstein, D. Brad Lanute, Diann E. Gaalema, Kiran Lakkaraju, Christina E. Warrender

College of Engineering and Mathematical Sciences Faculty Publications

Plug-in Hybrid Electric Vehicles (PHEVs) show potential to reduce greenhouse gas (GHG) emissions, increase fuel efficiency, and offer driving ranges that are not limited by battery capacity. However, these benefits will not be realized if consumers do not adopt this new technology. Several agent-based models have been developed to model potential market penetration of PHEVs, but gaps in the available data limit the usefulness of these models. To address this, we administered a survey to 1000 stated US residents, using Amazon Mechanical Turk, to better understand factors influencing the potential for PHEV market penetration. Our analysis of the survey results …