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Articles 1 - 30 of 31
Full-Text Articles in Engineering
How Can We Best Manage Freeway Congestion?, Robert Bertini, Christopher Monsere
How Can We Best Manage Freeway Congestion?, Robert Bertini, Christopher Monsere
TREC Project Briefs
Researchers from Portland State University evaluate Oregon’s Implementation of System-Wide Adaptive Ramp Metering (SWARM).
Using Archived Its Data To Measure The Operational Benefits Of A System-Wide Adaptive Ramp Metering System, Robert L. Bertini, Christopher Monsere, Oren Eshel, Soyoung Ahn
Using Archived Its Data To Measure The Operational Benefits Of A System-Wide Adaptive Ramp Metering System, Robert L. Bertini, Christopher Monsere, Oren Eshel, Soyoung Ahn
Civil and Environmental Engineering Faculty Publications and Presentations
A System-Wide Adaptive Ramp Metering (SWARM) system has been implemented in the Portland, Oregon metropolitan area, replacing the previous pre-timed ramp-metering system that had been in operation since 1981. SWARM has been deployed on six major corridors and operates during the morning and afternoon peak hours. This report presents results of a "before" and "after" evaluation of the performance of two freeway corridors as part of ongoing efforts to measure the benefits of the new SWARM system, as compared to the pre-timed system. The study benefited from using the existing regional data, surveillance and communications infrastructure in addition to a …
Progress Toward Meeting The Challenges Of Our Coastal Urban Future, Juile Pullen, Jason Ching, David J. Sailor, William Thompson, Bob Bornstein, Darko Koracin
Progress Toward Meeting The Challenges Of Our Coastal Urban Future, Juile Pullen, Jason Ching, David J. Sailor, William Thompson, Bob Bornstein, Darko Koracin
Mechanical and Materials Engineering Faculty Publications and Presentations
The article provides information on the Seventh Conference on Coastal Atmospheric and Oceanic Prediction and Processes, and the Seventh Symposium on the Urban Environment in San Diego, California on September 9-13, 2008. Topics include the heterogeneity of urban areas, coastal vulnerabilities, urban planning, and emergency response modeling. The conference featured several speakers including Walter Dabberdt and James Voogt.
Technology Forecasting For Wireless Communication, Timothy R. Anderson, Tugrul Unsal Daim, Jisun Kim
Technology Forecasting For Wireless Communication, Timothy R. Anderson, Tugrul Unsal Daim, Jisun Kim
Engineering and Technology Management Faculty Publications and Presentations
Wireless communications technologies have undergone rapid changes over the last 30 years from analog approaches to digital-based systems. These technologies have improved on many fronts including bandwidth, range, and power requirements. Development of new telecommunications technologies is critical. It requires many years of efforts. In order to be competitive, it is critical to establish a roadmap of future technologies. This paper presents a framework to characterize, assess and forecast the wireless communication technologies. A DEA-based methodology was used for predicting the state-of-the-art in future wireless communications technologies.
A Method For Processing Acoustic Doppler Current Profiler Velocity Data From Towed, Undulating Vehicles, David A. Jay, Jiayi Pan
A Method For Processing Acoustic Doppler Current Profiler Velocity Data From Towed, Undulating Vehicles, David A. Jay, Jiayi Pan
Civil and Environmental Engineering Faculty Publications and Presentations
The utility of the acoustic Doppler current profiler (ADCP) for sampling small time and space scales of coastal environments can be enhanced by mounting a high-frequency (1200 kHz) ADCP on an oscillating towed body. This approach requires both an external reference to convert the measured shears to velocities in the earth coordinates and a method to determine the towed body velocities. During the River Influence on the Shelf Ecosystems (RISE) project cruise, a high-frequency (1200 kHz) and narrowbeam ADCP with mode 12 sampling was mounted on a TRIAXUS oscillating towfish, which steers a 3D path behind the ship. This deployment …
The Inverse Ocean Modeling System. Part Ii: Applications, J. C. Muccino, H. G. Arango, Andrew F. Bennett, B. S. Chua, Julia Muccino Cornuelle, E. Di Lorenzo, Gary D. Egbert, D. Haidvogel, J. C. Levin, H. Luo, A. J. Miller, A. M. Moore, Edward D. Zaron
The Inverse Ocean Modeling System. Part Ii: Applications, J. C. Muccino, H. G. Arango, Andrew F. Bennett, B. S. Chua, Julia Muccino Cornuelle, E. Di Lorenzo, Gary D. Egbert, D. Haidvogel, J. C. Levin, H. Luo, A. J. Miller, A. M. Moore, Edward D. Zaron
Civil and Environmental Engineering Faculty Publications and Presentations
The Inverse Ocean Modeling (IOM) System is a modular system for constructing and running weak-constraint four-dimensional variational data assimilation (W4DVAR) for any linear or nonlinear functionally smooth dynamical model and observing array. The IOM has been applied to four ocean models with widely varying characteristics. The Primitive Equations Z-coordinate-Harmonic Analysis of Tides (PEZ-HAT) and the Regional Ocean Modeling System (ROMS) are three-dimensional, primitive equations models while the Advanced Circulation model in 2D (ADCIRC-2D) and Spectral Element Ocean Model in 2D (SEOM-2D) are shallow-water models belonging to the general finite-element family. These models, in conjunction with the IOM, have been used …
A Better Nondimensionalization Scheme For Slender Laminar Flows: The Laplacian Operator Scaling Method, Mark M. Weislogel, Yongkang Chen, D. Bolleddula
A Better Nondimensionalization Scheme For Slender Laminar Flows: The Laplacian Operator Scaling Method, Mark M. Weislogel, Yongkang Chen, D. Bolleddula
Mechanical and Materials Engineering Faculty Publications and Presentations
A scaling of the two-dimensional Laplacian operator is demonstrated for certain solutions (at least) to Poisson’s equation. It succeeds by treating the operator as a single geometric scale entity. The belated and rather subtle method provides an efficient assessment of the geometrical dependence of the problem and is preferred when practicable to the hydraulic diameter or term-by-term scaling for slender fully developed laminar flows. The improved accuracy further reduces the reliance of problems on widely varying numerical data or cumbersome theoretical forms and improves the prospects of exact or approximate theoretical analysis. Simple example problems are briefly described that demonstrate …
Lidar System Model For Use With Path Obscurants And Experimental Validation, J. W. Giles, I. N. Bankman, R. M. Sova, T. R. Morgan, Donald D. Duncan, J. A. Millard, W. J. Green, F. J. Marcotte
Lidar System Model For Use With Path Obscurants And Experimental Validation, J. W. Giles, I. N. Bankman, R. M. Sova, T. R. Morgan, Donald D. Duncan, J. A. Millard, W. J. Green, F. J. Marcotte
Electrical and Computer Engineering Faculty Publications and Presentations
When lidar pulses travel through a short path that includes a relatively high concentration of aerosols, scattering phenomena can alter the power and temporal properties of the pulses significantly, causing undesirable effects in the received pulse. In many applications the design of the lidar transmitter and receiver must consider adverse environmental aerosol conditions to ensure the desired performance. We present an analytical model of lidar system operation when the optical path includes aerosols for use in support of instrument design, simulations, and system evaluation. The model considers an optical path terminated with a solid object, although it can also be …
Modeling Broadband Ocean Acoustic Transmissions With Time-Varying Sea Surfaces, Martin Siderius, Michael B. Porter
Modeling Broadband Ocean Acoustic Transmissions With Time-Varying Sea Surfaces, Martin Siderius, Michael B. Porter
Electrical and Computer Engineering Faculty Publications and Presentations
Solutions to ocean acoustic scattering problems are often formulated in the frequency domain, which implies that the surface is "frozen" in time. This may be reasonable for short duration signals but breaks down if the surface changes appreciably over the transmission time. Frequency domain solutions are also impractical for source-receiver ranges and frequency bands typical for applications such as acoustic communications (e.g. hundreds to thousands of meters, 1-50 kHz band). In addition, a driving factor in the performance of certain acoustic systems is the Doppler spread, which is often introduced from sea-surface movement. The time-varying nature of the sea surface …
Effects Of Ambient Velocity Shear On Nonlinear Internal Wave Associated Mixing At The Columbia River Plume Front, Jiayi Pan, David A. Jay
Effects Of Ambient Velocity Shear On Nonlinear Internal Wave Associated Mixing At The Columbia River Plume Front, Jiayi Pan, David A. Jay
Civil and Environmental Engineering Faculty Publications and Presentations
Large-amplitude nonlinear internal waves (NLIWs) are frequently observed propagating away from Columbia River tidal plume fronts. They are generated because of the deceleration of the frontal bulge. During the River Influences on Shelf Ecosystems project cruises, the velocity, density structure and acoustic backscatter of the plume fronts and frontal NLIWs were observed using a towed vehicle, vessel-mounted instrumentation, and a vessel X band radar. These observations indicate that in the presence of strong ambient velocity shear, the NLIWs with maximum amplitudes occur well below the density interface and at a depth deeper than in the absence of shear. This deepening …
2007 Portland Metropolitan Region Transportation System Performance Report, Robert Bertini
2007 Portland Metropolitan Region Transportation System Performance Report, Robert Bertini
Civil and Environmental Engineering Faculty Publications and Presentations
Our transportation system is a key ingredient in the economy, quality of life and urban fabric of the Portland metropolitan area. It has been stated in the past that it is not possible to manage our transportation system tomorrow unless we understand how it is performing today. In this spirit, the Portland State University Center for Transportation Studies has been working with regional and statewide partners to develop new capabilities to measure, monitor and track the performance of the transportation system in real time and using archived data sources. We believe that it is possible to leverage these disparate data …
An Iterative Route Construction And Improvement Algorithm For The Vehicle Routing Problem With Soft And Hard Time Windows, Miguel A. Figliozzi
An Iterative Route Construction And Improvement Algorithm For The Vehicle Routing Problem With Soft And Hard Time Windows, Miguel A. Figliozzi
Civil and Environmental Engineering Faculty Publications and Presentations
The joint solution of routing problems with soft and hard time windows has valuable practical applications. Simultaneous solution approaches to both types of problems are needed when: (a) the number of routes needed for hard time windows exceeds the number of available vehicles, (b) a study of cost-service tradeoffs is required or the dispatcher has qualitative information regarding the relative importance of hard time window constraints across customers. A new Iterative Route Construction and Improvement (IRCI) algorithm of average run time performance O(n2 ) is proposed to sequentially solve Vehicle Routing Problems with Soft Time Windows (VRPSTW) and Hard Time …
Hydrologic Remote Sensing And Land Surface Data Assimilation, Hamid Moradkhani
Hydrologic Remote Sensing And Land Surface Data Assimilation, Hamid Moradkhani
Civil and Environmental Engineering Faculty Publications and Presentations
Accurate, reliable and skillful forecasting of key environmental variables such as soil moisture and snow are of paramount importance due to their strong influence on many water resources applications including flood control, agricultural production and effective water resources management which collectively control the behavior of the climate system. Soil moisture is a key state variable in land surface?atmosphere interactions affecting surface energy fluxes, runoff and the radiation balance. Snow processes also have a large influence on land-atmosphere energy exchanges due to snow high albedo, low thermal conductivity and considerable spatial and temporal variability resulting in the dramatic change on surface …
Measurement Of Oxygen Saturation In The Retina With A Spectroscopic Sensitive Multi Aperture Camera, Jessica C. Ramella-Roman, Scott A. Mathews, Haripriya Kandimalla, Afshin Nabili, Donald D. Duncan, Salvatore A. D'Anna, Syed M. Shah, Quan D. Nguyen
Measurement Of Oxygen Saturation In The Retina With A Spectroscopic Sensitive Multi Aperture Camera, Jessica C. Ramella-Roman, Scott A. Mathews, Haripriya Kandimalla, Afshin Nabili, Donald D. Duncan, Salvatore A. D'Anna, Syed M. Shah, Quan D. Nguyen
Electrical and Computer Engineering Faculty Publications and Presentations
We introduce a new multi aperture system capable of capturing six identical images of the human fundus at six different spectral bands. The system is based on a lenslet array architecture and is well suited for spectroscopy application. The multi-aperture system was interfaced with a fundus camera to acquire spectroscopic sensitive images of the retina vessel and ultimately to calculate oxygen saturation in the retina in vivo. In vitro testing showed that the system is able to accurately reconstruct curves of partially oxygenated hemoglobin. In vivo testing on healthy volunteers was conducted and yielded results of oxygen saturation similar to …
Bottom Profiling By Correlating Beam-Steered Noise Sequences, Chris H. Harrison, Martin Siderius
Bottom Profiling By Correlating Beam-Steered Noise Sequences, Chris H. Harrison, Martin Siderius
Electrical and Computer Engineering Faculty Publications and Presentations
It has already been established that by cross-correlating ambient noisetime series received on the upward and downward steered beams of a drifting vertical array one can obtain a subbottom layer profile. Strictly, the time differential of the cross correlation is the impulse response of the seabed. Here it is shown theoretically and by simulation that completely uncorrelated surfacenoise results in a layer profile with predictable amplitudes proportional to those of an equivalent echo sounder at the same depth as the array. The phenomenon is simulated by representing the sound sources as multiple random time sequences emitted from random locations in …
Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck
Physics Faculty Publications and Presentations
Two novel (and proprietary) strategies for the structural identification of a nanocrystal from either a single high-resolution (HR) transmission electron microscopy (TEM) image or a single precession electron diffraction pattern are proposed and their advantages discussed in comparison to structural fingerprinting from powder X-ray diffraction patterns. Simulations for cubic magnetite and maghemite nanocrystals are used as examples.
A Strategy For Reducing The Impact Of Driving Under Influence Of Intoxicants In Portland, Oregon, Christopher Monsere, Delia Chi
A Strategy For Reducing The Impact Of Driving Under Influence Of Intoxicants In Portland, Oregon, Christopher Monsere, Delia Chi
Civil and Environmental Engineering Faculty Publications and Presentations
Driving under the influence of intoxicants (DUII) applies to operating a vehicle under the influence of any substance that can impair driving performance. Nationally and locally there is a strong desire to reduce the societal impacts of this significant social problem. The trend in U.S. alcohol-related motor vehicle crashes was generally decreasing in the mid to late 1980’s but has remained fairly flat since the early 1990s. In 1982, approximately 60% of all US traffic fatalities were alcohol-related. By 1994, this had decreased to 43% but in the decade that followed it has changed little. In 2005, nearly 39% of …
Nano Quasicrystal Formation And Local Atomic Structure In Zr––Pd And Zr––Pt Binary Metallic Glasses, Junji Saida, Takashi Sanada, Shigeo Sato, Muneyuki Imafuku, Chunfei Li, Akihisa Inoue
Nano Quasicrystal Formation And Local Atomic Structure In Zr––Pd And Zr––Pt Binary Metallic Glasses, Junji Saida, Takashi Sanada, Shigeo Sato, Muneyuki Imafuku, Chunfei Li, Akihisa Inoue
Center for Electron Microscopy and Nanofabrication Publications and Presentations
Formation of the nanoscale icosahedral quasicrystalline phase (I-phase) in the melt-spun Zr70Pd30 and Zr80Pt20 binary metallic glasses were reported. Local atomic structure in the glassy and quasicrystal (QC)-formed states were also analyzed by XRD and EXAFS measurements in order to investigate the formation mechanism of QC phase. The distorted icosahedral-like local structure can be identified around Zr atom in the Zr70Pd30 metallic glass. In the QC formation process, a change of local environment around Zr is detected, in which the approximately one Zr atom substitutes for one Pd atom. In contrast, …
Monte Carlo Modeling Of Spatial Coherence: Free-Space Diffraction, Donald D. Duncan, David G. Fischer, Scott A. Prahl
Monte Carlo Modeling Of Spatial Coherence: Free-Space Diffraction, Donald D. Duncan, David G. Fischer, Scott A. Prahl
Electrical and Computer Engineering Faculty Publications and Presentations
We present a Monte Carlo method for propagating partially coherent fields through complex deterministic optical systems. A Gaussian copula is used to synthesize a random source with an arbitrary spatial coherence function. Physical optics and Monte Carlo predictions of the first- and second-order statistics of the field are shown for coherent and partially coherent sources for free-space propagation, imaging using a binary Fresnel zone plate, and propagation through a limiting aperture. Excellent agreement between the physical optics and Monte Carlo predictions is demonstrated in all cases. Convergence criteria are presented for judging the quality of the Monte Carlo predictions.
The Copula: A Tool For Simulating Speckle Dynamics, Donald D. Duncan, Sean J. Kirkpatrick
The Copula: A Tool For Simulating Speckle Dynamics, Donald D. Duncan, Sean J. Kirkpatrick
Electrical and Computer Engineering Faculty Publications and Presentations
Use of a copula for generating a sequence of correlated speckle patterns is introduced. The chief characteristic of this algorithm is that it generates a continuous speckle sequence with a specified evolution of the correlation and does so with just two arrays of random numbers. Thus, physically realistic temporally varying speckle patterns with proper first- and second-order statistics are easily realized. We illustrate use of the algorithm for generating sequences with prescribed Gaussian, exponential, and equal-interval correlations and demonstrate how correlation times can be specified independently. This approach to generating sequences of random realizations with prescribed correlations should prove useful …
New Particle Formation In The Front Range Of The Colorado Rocky Mountains, Micahel Boy, Thomas Karl, Andrew Turnipseed, Roy Lee Mauldin, Edward Kosciuch, James Greenberg, Jeff Rathbone, James Smith, Andreas Held, Kelley Barsanti, Alex Guenther
New Particle Formation In The Front Range Of The Colorado Rocky Mountains, Micahel Boy, Thomas Karl, Andrew Turnipseed, Roy Lee Mauldin, Edward Kosciuch, James Greenberg, Jeff Rathbone, James Smith, Andreas Held, Kelley Barsanti, Alex Guenther
Civil and Environmental Engineering Faculty Publications and Presentations
New particle formation is of interest because of its influence on the properties of aerosol population, and due to the possible contribution of newly formed particles to cloud condensation nuclei. Currently no conclusive evidence exists as to the mechanism or mechanisms of nucleation and subsequent particle growth. However, nucleation rates exhibit a clear dependence on ambient sulphuric acid concentrations and particle growth is often attributed to the condensation of organic vapours. A detailed study of new particle formation in the Front Range of the Colorado Rocky Mountains is presented here. Gas and particle measurement data for 32 days was analyzed …
Seasonal Variability And Estuary-Shelf Interactions In Circulation Dynamics Of A River-Dominated Estuary, Arun Chawla, David A. Jay, Antonio M. Baptista, Michael Wilkin, Charles Seaton
Seasonal Variability And Estuary-Shelf Interactions In Circulation Dynamics Of A River-Dominated Estuary, Arun Chawla, David A. Jay, Antonio M. Baptista, Michael Wilkin, Charles Seaton
Civil and Environmental Engineering Faculty Publications and Presentations
The long-term response of circulation processes to external forcing has been quantified for the Columbia River estuary using in situ data from an existing coastal observatory. Circulation patterns were determined from four Acoustic Doppler Profilers (ADP) and several conductivity-temperature sensors placed in the two main channels. Because of the very strong river discharge, baroclinic processes play a crucial role in the circulation dynamics, and the interaction of the tidal and subtidal baroclinic pressure gradients plays a major role in structuring the velocity field. The input of river flow and the resulting low-frequency flow dynamics in the two channels are quite …
Using Agent Based Simulation And Game Theory Analysis To Study Information Sharing In Organizations – The Infoscape, Richard Donald Jolly, Wayne W. Wakeland
Using Agent Based Simulation And Game Theory Analysis To Study Information Sharing In Organizations – The Infoscape, Richard Donald Jolly, Wayne W. Wakeland
Systems Science Faculty Publications and Presentations
Information sharing in organizations, especially the impact of sharing freely versus not sharing, was studied using game theory and agent based simulation. A game theoretic analysis was performed, and Netlogo simulations were carried out wherein some agents hoarded information while others shared information. As expected, sharing was found to greatly increase the overall amount of information within the organization. Unexpectedly, agents who share acquire more information than hoarders. This is due to the synergy that develops between groups of agents who are sharing with each other. The density of the agents is important-as the density increases, the probability increases that …
Emergence Of Networks In Distance-Constrained Trade, Kumar Venkat, Wayne W. Wakeland
Emergence Of Networks In Distance-Constrained Trade, Kumar Venkat, Wayne W. Wakeland
Systems Science Faculty Publications and Presentations
Long-distance trade has been rapidly increasing in recent years. As traders from around the world exchange goods, they form networks with traders as nodes and transactions as links. We use an agent-based model of a simple artificial economy to examine the emergence of trade networks when the distance between traders matters. Distance can become an issue if fuel for transportation becomes expensive or if greenhouse gas emissions from transportation become a major concern. We model the distance constraint as a transaction cost proportional to the amount of goods traded and the distance that those goods must be transported. We find …
Optimal Bus Stop Spacing For Minimizing Transit Operation Cost, Huan Li, Robert L. Bertini
Optimal Bus Stop Spacing For Minimizing Transit Operation Cost, Huan Li, Robert L. Bertini
Civil and Environmental Engineering Faculty Publications and Presentations
With the increasing attention to finance issues relative to transit operation, a bus stop spacing model is generated with the aim at minimizing the operation cost without impact on transit accessibility. Two cost functions are considered in the model including passenger access cost and in-vehicle passenger stopping cost aiming at minimizing total cost. A bus route in Portland, Oregon, USA is examined as an example using Archived Bus Dispatch System (BDS) data provided by TriMet, the regional transit provider for the Portland, Oregon metropolitan area. Based on the optimization model, the theoretical optimized bus stop spacing is 930 feet comparing …
Statistics Of Local Speckle Contrast, Donald D. Duncan, Sean J. Kirkpatrick, Ruikang K. Wang
Statistics Of Local Speckle Contrast, Donald D. Duncan, Sean J. Kirkpatrick, Ruikang K. Wang
Electrical and Computer Engineering Faculty Publications and Presentations
In describing the first-order properties of laser speckle under polarized illumination conditions, it is almost an article of faith that the contrast is unity. In many processing schemes, however, the contrast defined as the quotient of the standard deviation and the mean is calculated over a localized spatial region. In such cases, this local contrast displays a distribution of values that can depart substantially from unity. Properties of this distribution depend on details of the data acquisition and on the size of the local neighborhood over which the contrast is calculated. We demonstrate that this local contrast can be characterized …
Can Laser Speckle Flowmetry Be Made A Quantitative Tool?, Donald D. Duncan, Sean J. Kirkpatrick
Can Laser Speckle Flowmetry Be Made A Quantitative Tool?, Donald D. Duncan, Sean J. Kirkpatrick
Electrical and Computer Engineering Faculty Publications and Presentations
The ultimate objective of laser speckle flowmetry (and a host of specific implementations such as laser speckle contrast analysis, LASCA or LSCA; laser speckle spatial contrast analysis, LSSCA; laser speckle temporal contrast analysis, LSTCA; etc.) is to infer flow velocity from the observed speckle contrast. Despite numerous demonstrations over the past 25 years of such a qualitative relationship, no convincing quantitative relationship has been proven. One reason is a persistent mathematical error that has been propagated by a host of workers; another is a misconception about the proper autocorrelation function for ordered flow. Still another hindrance has been uncertainty in …
Combining Climate, Crash, And Highway Data For Improved Ranking Of Speed And Winter-Weather Related Crash Locations In Oregon, Christopher M. Monsere, Peter G. Bosa, Robert L. Bertini
Combining Climate, Crash, And Highway Data For Improved Ranking Of Speed And Winter-Weather Related Crash Locations In Oregon, Christopher M. Monsere, Peter G. Bosa, Robert L. Bertini
Civil and Environmental Engineering Faculty Publications and Presentations
In recent years, the techniques for screening transportation networks to identify high crash locations have become more sophisticated. Many transportation agencies, however, lack sufficient data, either in timeliness, completeness, or accuracy to implement many of the recent advances. This paper presents the results of an empirical analysis of screening and ranking for specific crash type (speed and ice related crashes) on rural 1.6 km (1 mi) highway sections of Oregon highways. The analysis includes data generated with the extensive use of spatial techniques and incorporates climate data to enhance environmental considerations. The paper compares the results of five ranking methods—critical …
Suspended Sediment Fluxes At An Intertidal Flat: The Shifting Influence Of Wave, Wind, Tidal, And Freshwater Forcing, Stefan A. Talke, Mark T. Stacey
Suspended Sediment Fluxes At An Intertidal Flat: The Shifting Influence Of Wave, Wind, Tidal, And Freshwater Forcing, Stefan A. Talke, Mark T. Stacey
Civil and Environmental Engineering Faculty Publications and Presentations
Using in situ, continuous, high frequency (8–16 Hz) measurements of velocity, suspended sediment concentration (SSC), and salinity, we investigate the factors affecting near-bed sediment flux during and after a meteorological event (cold front) on an intertidal flat in central San Francisco Bay. Hydrodynamic forcing occurs over many frequency bands including wind wave, ocean swell, seiching (500–1000 s), tidal, and infra-tidal frequencies, and varies greatly over the time scale of hours and days. Sediment fluxes occur primarily due to variations in flow and SSC at three different scales: residual (tidally averaged), tidal, and seiching. During the meteorological event, sediment fluxes are …
Daily Forecasts Of Columbia River Plume Circulation: A Tale Of Spring/Summer Cruises, Yinglong J. Zhang, Antonio M. Baptista, Barbara M. Hickey, Byron C. Crump, David A. Jay, Michael Wilkin, Charles Seaton
Daily Forecasts Of Columbia River Plume Circulation: A Tale Of Spring/Summer Cruises, Yinglong J. Zhang, Antonio M. Baptista, Barbara M. Hickey, Byron C. Crump, David A. Jay, Michael Wilkin, Charles Seaton
Civil and Environmental Engineering Faculty Publications and Presentations
Semi-operational daily forecasts of circulation from an observatory for the Columbia River estuary-plume-shelf system routinely support oceanographic cruises, by providing 24h-ahead estimates of plume location and structure for planning purposes and for near real-time interpretation of observations. This paper analyzes forecast skill during spring/summer cruises in 2004-2007. Assessment addresses both qualitative descriptions of major plume trends and features and quantitative representation of data from (primarily) vessel-based flow-through, cast and towed systems. Forecasts emerge as robust predictors of plume location and variability, with skill that has grown over time, at least in part due to improvements in model algorithms. When the …