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Articles 61 - 90 of 371
Full-Text Articles in Engineering
Performance Of Us Concrete Highway Bridge Decks Characterized By Random Parameters Binary Logistic Regression, Omar Ghonima, Jason C. Anderson, Thomas Schumacher, Avinash Unnikrishnan
Performance Of Us Concrete Highway Bridge Decks Characterized By Random Parameters Binary Logistic Regression, Omar Ghonima, Jason C. Anderson, Thomas Schumacher, Avinash Unnikrishnan
Civil and Environmental Engineering Faculty Publications and Presentations
This study employs a random parameters binary logistic regression (LR) to characterize the impact of environmental and structural parameters on concrete highway bridge deck deterioration nationwide. Two specific gaps in the literature are addressed: (1) the use of a nationwide dataset for analysis, and (2) the implementation of a methodology to account for unobserved heterogeneity. A total of 3,262 bridge deck deterioration observations derived from the authors’ nationwide concrete highway bridge deck performance inventory (NCBDPI) database were used in this study. The deterioration rate (DR) was computed as the decrease in the concrete bridge deck condition rating ( …
Improved Denoising Of Structural Vibration Data Employing Bilateral Filtering, Ning Liu, Thomas Schumacher
Improved Denoising Of Structural Vibration Data Employing Bilateral Filtering, Ning Liu, Thomas Schumacher
Civil and Environmental Engineering Faculty Publications and Presentations
With the continuous advancement of data acquisition and signal processing, sensors, and wireless communication, copious research work has been done using vibration response signals for structural damage detection. However, in actual projects, vibration signals are often subject to noise interference during acquisition and transmission, thereby reducing the accuracy of damage identification. In order to effectively remove the noise interference, bilateral filtering, a filtering method commonly used in the field of image processing for improving data signal-to-noise ratio was introduced. Based on the Gaussian filter, the method constructs a bilateral filtering kernel function by multiplying the spatial proximity Gaussian kernel function …
Sea Level, Tidal, And River Flow Trends In The Lower Columbia River Estuary, 1853-Present, Stefan Talke, Andrew Mahedy, David A. Jay, Patrick Lau, Conrad Hilley, Amanda Hudson
Sea Level, Tidal, And River Flow Trends In The Lower Columbia River Estuary, 1853-Present, Stefan Talke, Andrew Mahedy, David A. Jay, Patrick Lau, Conrad Hilley, Amanda Hudson
Civil and Environmental Engineering Faculty Publications and Presentations
Few tidal records are available pre-1900 for the Pacific Ocean. We improve data coverage by recovering historical tabulations and digitizing analog tide rolls from Astoria, Oregon for 1853-1876. Nearly 13,500 overlapping images of tides from 1855-1870 were digitized at a 6 minute resolution using a line-finding algorithm. Available hourly and high/low tabulations were also digitized, as were nearby hourly records from 1933-1943. Uncertainty was assessed by evaluating manual staff measurements, historical documents, and leveling surveys. Results suggest that uncertainty in mean sea level varies from ± 0.07m (early 1850s) to ± 0.03m (1867-1876) and is driven primarily by datum and …
Analytical And Field Verification Of A 3d Hydrodynamic And Water Quality Numerical Scheme Based On The 2d Formulation In Ce-Qual-W2, Hussein Ali Mahdi Al-Zubaidi, Scott A. Wells
Analytical And Field Verification Of A 3d Hydrodynamic And Water Quality Numerical Scheme Based On The 2d Formulation In Ce-Qual-W2, Hussein Ali Mahdi Al-Zubaidi, Scott A. Wells
Civil and Environmental Engineering Faculty Publications and Presentations
A new 3D hydrodynamic model was developed to simulate water quality transport in surface waterbodies. The governing equations are the continuity equation, free surface equation, momentum equation and transport equation. The 2D numerical scheme of CE-QUAL-W2 was expanded in three dimensions and modified to solve for the free surface elevation. A time splitting technique was employed to solve the momentum and transport equation. The numerical formulation of the 3D scheme used a novel solution, which resulted in a tri-diagonal matrix form for solving the free surface equation rather than a more computationally intensive penta-diagonal matrix solution. In addition, the hydrodynamic …
Right-Hook Crash Scenario: Effects Of Environmental Factors On Driver's Visual Attention And Crash Risk, Mafruhatul Jannat, Hagai Tapiro, Christopher Monsere, David Hurwitz
Right-Hook Crash Scenario: Effects Of Environmental Factors On Driver's Visual Attention And Crash Risk, Mafruhatul Jannat, Hagai Tapiro, Christopher Monsere, David Hurwitz
Civil and Environmental Engineering Faculty Publications and Presentations
A right-hook (RH) crash is a common type of bicycle–motor vehicle crash that occurs between a right-turning vehicle and through-moving bicycle at an intersection in right-hand driving countries. Despite the frequency and severity of this crash type, no significant driver-performance based evidence of the causes of RH crashes at signalized intersections was found in the literature. This study examined the driver’s visual attention in a right-turning scenario at signalized intersections with bicycle lanes but no exclusive right-turning lanes while interacting with a bicyclist to develop an understanding of RH crash causality. Fifty-one participants in 21 simulated road scenarios performed a …
A Study Of The Competitiveness Of Autonomous Delivery Vehicles In Urban Areas, Miguel A. Figliozzi, Dylan Jennings
A Study Of The Competitiveness Of Autonomous Delivery Vehicles In Urban Areas, Miguel A. Figliozzi, Dylan Jennings
Civil and Environmental Engineering Faculty Publications and Presentations
The rapid growth of e-commerce and package deliveries across the globe is demanding new solutions to meet customers’ desire for more and faster deliveries. This research focuses on the cost competitiveness of autonomous air and ground delivery vehicles. Three types of autonomous vehicle are analyzed: drones, sidewalk autonomous delivery robots (SADRs), and road autonomous delivery robots (RADRs). Autonomous vehicles are compared against a typical delivery van. The impact of capacity, range and time constraints are analyzed. Results show that each type of autonomous delivery vehicle is suitable in different scenarios and can therefore complement each other to reduce costs or …
Understanding Roundabout Safety Through The Application Of Advanced Econometric Techniques, Hamsa Abbas Zubaidi, Jason C. Anderson, Salvador Hernandez
Understanding Roundabout Safety Through The Application Of Advanced Econometric Techniques, Hamsa Abbas Zubaidi, Jason C. Anderson, Salvador Hernandez
Civil and Environmental Engineering Faculty Publications and Presentations
Intersections present a significant safety concern, as such in an effort to reduce the more serious injuries occurring at or near intersections, many jurisdictions have turned to implementing roundabouts. Despite the advantages that roundabouts provide, crashes still occur, and less severe crashes are on the rise. The study presented in this paper investigates a crash-based analysis to better understand the factors that may influence less severe crashes to those of more severe crashes given various roundabout configurations and crash types. Using Oregon’s crash database from 2011 to 2015 a series of log likelihood ratio tests were conducted to validate that …
Carbon Emissions Reductions In Last Mile And Grocery Deliveries Utilizing Autonomous Vehicles, Miguel A. Figliozzi
Carbon Emissions Reductions In Last Mile And Grocery Deliveries Utilizing Autonomous Vehicles, Miguel A. Figliozzi
Civil and Environmental Engineering Faculty Publications and Presentations
New driverless air and ground vehicles are being launched and tested to deliver products or services in the areas of retail, groceries, and healthcare. This research focuses on the efficiency of autonomous (driverless) delivery vehicles in terms of vehicle-miles, energy consumption, and carbon emissions. Drones or UAVs, sidewalk autonomous delivery robots (SADRs), and road autonomous delivery robots (RADRs) vehicles carbon emissions are compared against emissions from an electric van (e-van), a conventional internal combustion engine van, and driving to a store utilizing electric and conventional vehicles. The impacts of vehicle capacity, range, and time constraints are analyzed as well as …
Accessibility And Equity Analysis Of Common Carrier Parcel Lockers At Transit Facilities In Portland, Oregon, Katherine Keeling, Jaclyn S. Schaefer, Miguel Figliozzi
Accessibility And Equity Analysis Of Common Carrier Parcel Lockers At Transit Facilities In Portland, Oregon, Katherine Keeling, Jaclyn S. Schaefer, Miguel Figliozzi
Civil and Environmental Engineering Faculty Publications and Presentations
Transit goals have typically focused on commuter trips but facilitating urban last-mile freight logistics is a potential strategy to increase transit ridership and mitigate the demands of parcel distribution on the transportation network. Presently, most parcel lockers operate out of private businesses, but consumer surveys have found that transit users may be interested in locker facilities at transit connections. The implementation of an unmanned, secure, common carrier parcel locker system could have benefits for non-transit users as well. Consolidation of deliveries is expected to benefit courier companies by allowing operations at increasingly competitive rates, and retailers and consumers benefit from …
Tide-Storm Surge Interactions In Highly Altered Estuaries: How Channel Deepening Increases Surge Vulnerability, Ramin Familkhalili, Stefan A. Talke, David A. Jay
Tide-Storm Surge Interactions In Highly Altered Estuaries: How Channel Deepening Increases Surge Vulnerability, Ramin Familkhalili, Stefan A. Talke, David A. Jay
Civil and Environmental Engineering Faculty Publications and Presentations
We develop idealized analytical and numerical models to study how storm surge amplitudes vary within frictional, weakly convergent, nonreflective estuaries. Friction is treated using Chebyshev polynomials. Storm surge is represented as the sum of two sinusoidal components, and a third constituent represents the semidiurnal tide (D2). An empirical fit of storm surge shows that two sinusoidal components adequately represent storm surge above a baseline value (R2 = 0.97). We find that the spatial transformation of surge amplitudes depends on the depth of the estuary, and characteristics of the surge wave including time scale, amplitude, asymmetry, and surge‐tide relative phase. Analytical …
A Study Of Road Autonomous Delivery Robots And Their Potential Impacts On Freight Efficiency And Travel, Dylan Jennings, Miguel A. Figliozzi
A Study Of Road Autonomous Delivery Robots And Their Potential Impacts On Freight Efficiency And Travel, Dylan Jennings, Miguel A. Figliozzi
Civil and Environmental Engineering Faculty Publications and Presentations
Road autonomous mobile robots have attracted the attention of delivery companies and policy makers for their potential to reduce costs and increase urban freight efficiency. Established delivery companies and new startups are investing in technologies that reduce delivery times and/or increase delivery drivers’ productivity. In this context, the adoption of Road Automatic (or Autonomous) Delivery Robots (RADRs) has a growing appeal. Several RADRs are currently being tested in the United States. The key novel contributions of this research are: (a) an analysis of the characteristics and regulation of RADRs in the US and (b) a study of the relative travel, …
Factors Affecting Injury Severity In Vehicle-Pedestrian Crashes: A Day-Of-Week Analysis Using Random Parameter Ordered Response Models And Artificial Neural Networks, Seyedmirsajad Mokhtarimousavi, Jason C. Anderson, Atorod Azizinamini, Mohammed Hadi
Factors Affecting Injury Severity In Vehicle-Pedestrian Crashes: A Day-Of-Week Analysis Using Random Parameter Ordered Response Models And Artificial Neural Networks, Seyedmirsajad Mokhtarimousavi, Jason C. Anderson, Atorod Azizinamini, Mohammed Hadi
Civil and Environmental Engineering Faculty Publications and Presentations
The high number of vehicle–pedestrian crashes in the United State has gained increased attention among transportation safety analysts in recent years. Being directly exposed to the collision force makes pedestrians more prone to becoming severely injured when in crash than other road users. Considering the fact that pedestrian-involved crashes is a serious public health problem, the current study’s aim is to investigate the contributing factors associated with injury severity of pedestrian crashes by time-of-week. Separate injury severity models for weekday and weekend crashes were developed, and the overall stability of the model estimates was examined through likelihood ratio tests. For …
Performance Evaluation Of A Carbon Nanotube Sensor For Fatigue Crack Monitoring Of Metal Structures, Shafique Ahmed, Thomas Schumacher, Erik T. Thostenson, Jennifer Mcconnell
Performance Evaluation Of A Carbon Nanotube Sensor For Fatigue Crack Monitoring Of Metal Structures, Shafique Ahmed, Thomas Schumacher, Erik T. Thostenson, Jennifer Mcconnell
Civil and Environmental Engineering Faculty Publications and Presentations
This article describes research that investigated the ability of a carbon nanotube (CNT) sensor to detect and monitor fatigue crack initiation and propagation in metal structures. The sensor consists of a nonwoven carrier fabric with a thin film of CNT that is bonded to the surface of a structure using an epoxy adhesive. The carrier fabric enables the sensor to be easily applied over large areas with complex geometries. Furthermore, the distributed nature of the sensor improves the probability of detecting crack initiation and enables monitoring of crack propagation over time. Piezoresistivity of the sensor enables strains to be monitored …
Storm Tide Amplification And Habitat Changes Due To Urbanization Of A Lagoonal Estuary, Philip Orton, Eric W. Sanderson, Stefan Talke, Mario Giampieri, Kytt Macmanus
Storm Tide Amplification And Habitat Changes Due To Urbanization Of A Lagoonal Estuary, Philip Orton, Eric W. Sanderson, Stefan Talke, Mario Giampieri, Kytt Macmanus
Civil and Environmental Engineering Faculty Publications and Presentations
In recent centuries, human activities have greatly modified the geomorphology of coastal regions. However, studies of historical and possible future changes in coastal flood extremes typically ignore the influence of geomorphic change. Here, we quantify the influence of 20th-century man-made changes to Jamaica Bay, New York City, on present-day storm tides. We develop and validate a hydrodynamic model for the 1870s based on detailed maps of bathymetry, seabed characteristics, topography, and tide observations for use alongside a present-day model. Predominantly through dredging, landfill, and inlet stabilization, the average water depth of the bay increased from 1.7 to 4.5 m, tidal …
A Case Study Of Drone Delivery Reliability For Time-Sensitive Medical Supplies With Stochastic Demand And Meteorological Conditions, Travis B. Glick, Miguel Figliozzi, Avinash Unnikrishnan
A Case Study Of Drone Delivery Reliability For Time-Sensitive Medical Supplies With Stochastic Demand And Meteorological Conditions, Travis B. Glick, Miguel Figliozzi, Avinash Unnikrishnan
Civil and Environmental Engineering Faculty Publications and Presentations
Drones are increasingly being utilized to deliver medical supplies, and the COVID-19 pandemic has accelerated this trend. Drones arrive quickly by taking more direct paths and avoiding ground-based obstructions. However, drones are not completely reliable and may also experience failures and delays. For consumer products, delivery delays are an inconvenience, but for some medical supplies, delays may be fatal. This research focuses on the drone reliability of one particular type of supply and event: automatic defibrillators for out-of-hospital cardiac arrests (OHCA). A modeling framework is developed to analyze drone delivery reliability with stochastic demands and meteorological conditions. Using probability distributions …
An Empirical Study Of The Impacts Of Bicycles On Passenger Car Speeds On Urban Roads Without Bicycle Lanes, Jaclyn S. Schaefer, Miguel Figliozzi, Avinash Unnikrishnan
An Empirical Study Of The Impacts Of Bicycles On Passenger Car Speeds On Urban Roads Without Bicycle Lanes, Jaclyn S. Schaefer, Miguel Figliozzi, Avinash Unnikrishnan
Civil and Environmental Engineering Faculty Publications and Presentations
Higher bicycle mode share has been suggested as part of a solution to reduce the burden of congestion in urban areas. As strategies to promote bicycling are implemented, concerns have been raised by some road users and stakeholders citing simulation based traffic studies that indicate that an increase in the bicycle mode share generates major travel time delays via reduced vehicle speeds unless bicycle lanes are provided. The current research investigates the effects bicycles may have on motorized vehicle speeds on a variety of lower speed and volume urban roads without bicycle lanes. A detailed comparative analysis of passenger car …
Nineteenth-Century Tides In The Gulf Of Maine And Implications For Secular Trends, Richard D. Ray, Stefan A. Talke
Nineteenth-Century Tides In The Gulf Of Maine And Implications For Secular Trends, Richard D. Ray, Stefan A. Talke
Civil and Environmental Engineering Faculty Publications and Presentations
Since the early twentieth century, the amplitudes of tidal constituents in the Gulf of Maine and Bay of Fundy display clear secular trends that are among the largest anywhere observed for a regional body of water. The M2 amplitude at Eastport, Maine, increased at a rate of 14.1 ± 1.2 cm per century until it temporarily dropped during 1980–1990, apparently in response to changes in the wider North Atlantic. Annual tidal analyses indicate M2 reached an all‐time high amplitude last year (2018). Here we report new estimates of tides derived from nineteenth century water‐level measurements found in the U.S. National …
E-Grocery Home Delivery Impacts On Food Distribution, Access And Equity: A Portland Case Study, Miguel Figliozzi, Katherine Keeling
E-Grocery Home Delivery Impacts On Food Distribution, Access And Equity: A Portland Case Study, Miguel Figliozzi, Katherine Keeling
Civil and Environmental Engineering Faculty Publications and Presentations
The adoption of e-grocery home delivery (HD) has the potential to change social norms of acquiring household foods and sundries. This case study of Portland, OR reviews the new elements of distribution, inclusion, exclusion, and value created by the service of four major e-grocery businesses: Shipt, Instacart, Amazon Prime Now, and Walmart. These e-grocers are reviewed in terms of service areas, pricing, and inventory choice, as these are key factors on consumer experience. New distribution services are not confided or distributed around traditional industrial or wholesale land use areas. Coverage is extensive, in the Portland metropolitan statistical area, 94% of …
Hydrodynamic And Total Dissolved Solids Model Of The Tigris River Using Ce-Qual-W2, Muhanned D. Al-Murib, Scott Wells
Hydrodynamic And Total Dissolved Solids Model Of The Tigris River Using Ce-Qual-W2, Muhanned D. Al-Murib, Scott Wells
Civil and Environmental Engineering Faculty Publications and Presentations
The headwaters of the Tigris River basin in Iraq is controlled by Turkey due to a series of dams constructed over the last few decades. Since Total Dissolved Solids (TDS) in the Tigris River within Baghdad and downstream cities can reach 1000 mg/L exceeding both drinking water and irrigation guidelines, a hydrodynamic and water quality model, CE-QUAL-W2, of the river was developed to understand how changes in flow affect TDS downstream. A model of 880 km of the Tigris River from Mosul Dam to Kut Barrage including Tharthar Lake was constructed for 2009. Model development was challenging due to a …
Historical Changes In Lower Columbia River And Estuary Floods: A Numerical Study, Lumas Helaire, Stefan Talke, David A. Jay, Andrew Mahedy
Historical Changes In Lower Columbia River And Estuary Floods: A Numerical Study, Lumas Helaire, Stefan Talke, David A. Jay, Andrew Mahedy
Civil and Environmental Engineering Faculty Publications and Presentations
Over the past 150 years, the Lower Columbia River Estuary controlling depth has approximately doubled, the majority of historical wetlands and floodplain have been reclaimed, numerous infrastructure projects have altered and confined flow pathways, and significant natural and anthropogenic changes to the discharge hydrograph have occurred. To investigate the effect of these changes on tides, river slope, and flood water levels, we construct and validate numerical models that simulate flow over late nineteenth‐century and present‐day bathymetry. The models are validated using archival (1853–1877) and modern tide measurements throughout the Lower Columbia River Estuary and river stage measurements from the tidal …
Toward Realistic Nonstationarity Of Semidiurnal Baroclinic Tides In A Hydrodynamicmodel, Arin D. Nelson, Brian K. Arbic, Edward Zaron, Anna Savage, James G. Richman, Maarten C. Buijsman, Jay F. Shriver
Toward Realistic Nonstationarity Of Semidiurnal Baroclinic Tides In A Hydrodynamicmodel, Arin D. Nelson, Brian K. Arbic, Edward Zaron, Anna Savage, James G. Richman, Maarten C. Buijsman, Jay F. Shriver
Civil and Environmental Engineering Faculty Publications and Presentations
Semidiurnal baroclinic tide sea surface height (SSH) variance and semidiurnal nonstationary variance fraction (SNVF) are compared between a hydrodynamic model and altimetry for the low- to middle-latitude global ocean. Tidal frequencies are aliased by ∼10-day altimeter sampling, which makes it impossible to unambiguously identify nonstationary tidal signals from the observations. In order to better understand altimeter sampling artifacts, the model was analyzed using its native hourly outputs and by subsampling it in the same manner as altimeters. Different estimates of the semidiurnal nonstationary and total SSH variance are obtained with the model depending on whether they are identified in the …
Surface Kinetic Energy Distributions In The Global Oceans From A High-Resolution Numerical Model And Surface Drifter Observations, Xiaolong Yu, Aurelien Ponte, Shane Elipot, Dimitris Menemenlis, Edward Zaron, Ryan Abernathey
Surface Kinetic Energy Distributions In The Global Oceans From A High-Resolution Numerical Model And Surface Drifter Observations, Xiaolong Yu, Aurelien Ponte, Shane Elipot, Dimitris Menemenlis, Edward Zaron, Ryan Abernathey
Civil and Environmental Engineering Faculty Publications and Presentations
The surface kinetic energy of a 1/48◦ global ocean simulation and its distribution as a function of frequency and location are compared with the one estimated from 15,329 globally distributed surface drifter observations at hourly resolution. These distributions follow similar patterns with a dominant low-frequency component and well-defined tidal and near-inertial peaks globally. Quantitative differences are identified with deficits of low-frequency energy near the equator (factor 2) and at near-inertial frequencies (factor 3) and an excess of energy at semidiurnal frequencies (factor 4) for the model. Owing to its hourly resolution and its near-global spatial coverage, the array of surface …
Global Observations Of Fine-Scale Ocean Surface Topography With The Surface Water And Ocean Topography (Swot) Mission, Rosemary Morrow, Lee-Lueng Fu, Fabrice Ardhuin, Mounir Benkiran, Bertrand Chapron, Emmanuel Cosme, Francesco D’Ovidio, J. Thomas Farrar, Sarah T. Gille, Guillaume Lapeyre, Pierre-Yves Le Traon, Ananda Pascual, Aurélien Ponte, Bo Qiu, Nicolas Rascle, Clement Ubelmann, Jinbo Wang, Edward Zaron
Global Observations Of Fine-Scale Ocean Surface Topography With The Surface Water And Ocean Topography (Swot) Mission, Rosemary Morrow, Lee-Lueng Fu, Fabrice Ardhuin, Mounir Benkiran, Bertrand Chapron, Emmanuel Cosme, Francesco D’Ovidio, J. Thomas Farrar, Sarah T. Gille, Guillaume Lapeyre, Pierre-Yves Le Traon, Ananda Pascual, Aurélien Ponte, Bo Qiu, Nicolas Rascle, Clement Ubelmann, Jinbo Wang, Edward Zaron
Civil and Environmental Engineering Faculty Publications and Presentations
The future international Surface Water and Ocean Topography (SWOT) Mission, planned for launch in 2021, will make high-resolution 2D observations of sea-surface height using SAR radar interferometric techniques. SWOT will map the global and coastal oceans up to 77.6 latitude every 21 days over a swath of 120 km (20 km nadir gap). Today’s 2D mapped altimeter data can resolve ocean scales of 150 km wavelength whereas the SWOT measurement will extend our 2D observations down to 15–30 km, depending on sea state. SWOT will offer new opportunities to observe the oceanic dynamic processes at scales that are important in …
Simultaneous Estimation Of Ocean Tides And Underwater Topography In The Weddell Sea, Edward D. Zaron
Simultaneous Estimation Of Ocean Tides And Underwater Topography In The Weddell Sea, Edward D. Zaron
Civil and Environmental Engineering Faculty Publications and Presentations
A new model for theM2, S2, K1, and O1 tides in the Weddell Sea is developed by assimilating CryoSat-2 data into a barotropic tide model. A variational approach is used, which explicitly allows for errors in the water depth, that is, the bottom topography in open water and the water column thickness under floating ice shelves, so that an optimized estimate of the topography is obtained together with the tidal fields. In preparation for assimilation, the sensitivity of the tidal elevation to the interfacial drag at the sea floor and the ice-water interface (under the floating ice shelves) is investigated; …
Integrating Landsat Tm/Etm+ And Numerical Modeling To Estimatewater Temperature In The Tigris River Under Future Climate And Management Scenarios, Muhanned Al-Murib, Scott Wells, Stefan Talke
Integrating Landsat Tm/Etm+ And Numerical Modeling To Estimatewater Temperature In The Tigris River Under Future Climate And Management Scenarios, Muhanned Al-Murib, Scott Wells, Stefan Talke
Civil and Environmental Engineering Faculty Publications and Presentations
Modeling the water quality of rivers and assessing the effects of changing conditions is often hindered by a lack of in situ measurements for calibration. Here, we use a combination of satellite measurements, statistical models, and numerical modeling with CE-QUAL-W2 to overcome in situ data limitations and evaluate the effect of changing hydrologic and climate conditions on water temperature (Tw) in the Tigris River, one of the largest rivers in the Middle East. Because few in situ estimates of Tw were available, remotely-sensed estimates of Tw were obtained from Landsat satellite images at roughly 2 week intervals for …
Analysis And Application Of Log-Linear And Quantile Regression Models To Predict Bus Dwell Times, Travis B. Glick, Miguel Figliozzi
Analysis And Application Of Log-Linear And Quantile Regression Models To Predict Bus Dwell Times, Travis B. Glick, Miguel Figliozzi
Civil and Environmental Engineering Faculty Publications and Presentations
Understanding the key factors that contribute to transit travel times and travel time variability is an essential part of transit planning and research. Delay that occurs when buses service bus stops, dwell time, is one of the main sources of travel time variability and has therefore been the subject of ongoing research to identify and quantify its determinants. Previous research has focused on testing new variables using linear regressions that may be added to models to improve predictions. An important assumption of linear regression models used in past research efforts is homoscedasticity or the equal distribution of the residuals across …
Production Of Secondary Organic Aerosol During Aging Of Biomass Burning Smoke From Fresh Fuels And Its Relationship To Voc Precursors, A. T. Ahern, E. S. Robinson, D. S. Tkacik, L. E. Hatch, Kelley Barsanti, C. E. Stockwell, Robert J. Yokelson, Multiple Additional Authors
Production Of Secondary Organic Aerosol During Aging Of Biomass Burning Smoke From Fresh Fuels And Its Relationship To Voc Precursors, A. T. Ahern, E. S. Robinson, D. S. Tkacik, L. E. Hatch, Kelley Barsanti, C. E. Stockwell, Robert J. Yokelson, Multiple Additional Authors
Civil and Environmental Engineering Faculty Publications and Presentations
After smoke from burning biomass is emitted into the atmosphere, chemical and physical processes change the composition and amount of organic aerosol present in the aged, diluted plume. During the fourth Fire Lab at Missoula Experiment, we performed smog‐chamber experiments to investigate formation of secondary organic aerosol (SOA) and multiphase oxidation of primary organic aerosol (POA). We simulated atmospheric aging of diluted smoke from a variety of biomass fuels while measuring particle composition using high‐resolution aerosol mass spectrometry. We quantified SOA formation using a tracer ion for low‐volatility POA as a reference standard (akin to a naturally occurring internal standard). …
The Quest For Model Uncertainty Quantification: A Hybrid Ensemble And Variational Data Assimilation Framework, Peyman Abbaszadeh, Hamid Moradkhani, Dacian Daescu
The Quest For Model Uncertainty Quantification: A Hybrid Ensemble And Variational Data Assimilation Framework, Peyman Abbaszadeh, Hamid Moradkhani, Dacian Daescu
Civil and Environmental Engineering Faculty Publications and Presentations
This article presents a novel approach to couple a deterministic four‐dimensional variational (4DVAR) assimilation method with the particle filter (PF) ensemble data assimilation system, to produce a robust approach for dual‐state‐parameter estimation. In our proposed method, the Hybrid Ensemble and Variational Data Assimilation framework for Environmental systems (HEAVEN), we characterize the model structural uncertainty in addition to model parameter and input uncertainties. The sequential PF is formulated within the 4DVAR system to design a computationally efficient feedback mechanism throughout the assimilation period. In this framework, the 4DVAR optimization produces the maximum a posteriori estimate of state variables at the beginning …
Remote Sensing Of Water Use Efficiency And Terrestrial Drought Recovery Across The Contiguous United States, Behzad Ahmadi, Ali Ahmadalipour, Glenn Tootle
Remote Sensing Of Water Use Efficiency And Terrestrial Drought Recovery Across The Contiguous United States, Behzad Ahmadi, Ali Ahmadalipour, Glenn Tootle
Civil and Environmental Engineering Faculty Publications and Presentations
Ecosystem water-use efficiency (WUE) is defined as the ratio of carbon gain (i.e., gross primary productivity; GPP) to water consumption (i.e., evapotranspiration; ET). WUE is markedly influential on carbon and water cycles, both of which are fundamental for ecosystem state, climate and the environment. Drought can affect WUE, subsequently disturbing the composition and functionality of terrestrial ecosystems. In this study, the impacts of drought on WUE and its components (i.e., GPP and ET) are assessed across the Contiguous US (CONUS) at fine spatial and temporal resolutions. Soil moisture simulations from land surface modeling are utilized to detect and characterize agricultural …
Hydrological Drought Persistence And Recovery Over The Conus: A Multi-Stage Framework Considering Water Quantity And Quality, Behzad Ahmadi, Ali Ahmadalipour, Hamid Moradkhani
Hydrological Drought Persistence And Recovery Over The Conus: A Multi-Stage Framework Considering Water Quantity And Quality, Behzad Ahmadi, Ali Ahmadalipour, Hamid Moradkhani
Civil and Environmental Engineering Faculty Publications and Presentations
Hydrological droughts have considerable negative impacts on water quantity and quality, and understanding their regional characteristics is of crucial importance. This study presents a multi-stage framework to detect and characterize hydrological droughts considering both streamflow and water quality changes. Hydrological droughts are categorized into three stages of growth, persistence, retreat, and water quality variables (i.e., water temperature, dissolved oxygen concentration, and turbidity) are utilized to further investigate drought recovery. The framework is applied to 400 streamflow gauges across the Contiguous United States (CONUS) over the study period of 1950–2016. The method is illustrated for the 2012 US drought, which affected …