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Portland State University

2011

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Full-Text Articles in Engineering

Using Practical Supergain For Passive Imaging With Noise, Martin Siderius Dec 2011

Using Practical Supergain For Passive Imaging With Noise, Martin Siderius

Electrical and Computer Engineering Faculty Publications and Presentations

Recent work has shown that endfire beamforming of ocean noise can be used to produce images of the seabed layering [Siderius et al., J. Acoust. Soc. Am. 120, 1315–1323 (2006)]. This initial noise imaging technique used conventional beamforming and was later extended to adaptive beamforming that is theoretically optimal. However, there can be problems with adaptive methods, which include extreme sensitivity to random errors, the required averaging time, and computational complexity. Here, the concept of supergain is used to show that delay and sum beamforming can produce nearly the same results as the optimal adaptive methods without the drawbacks.


Decomposition Of Reversible Logic Function Based On Cube-Reordering, Martin Lukac, Michitaka Kameyama, Marek Perkowski, Pawel Kerntopf Dec 2011

Decomposition Of Reversible Logic Function Based On Cube-Reordering, Martin Lukac, Michitaka Kameyama, Marek Perkowski, Pawel Kerntopf

Electrical and Computer Engineering Faculty Publications and Presentations

We present a novel approach to the synthesis of incompletely specified reversible logic functions. The method is based on cube grouping; the first step of the synthesis method analyzes the logic function and generates groupings of same cubes in such a manner that multiple sub-functions are realized by a single Toffoli gate. This process also reorders the function in such a manner that not only groups of similarly defined cubes are joined together but also don’t care cubes. The proposed method is verified on standard benchmarks for both reversible and irreversible logic functions. The obtained results show that for ...


Application Of Genetic Algorithm For Synthesis Of Large Reversible Circuits Using Covered Set Partitions, Maher Mofeid Hawash, Baker Abdalhaq, Amjad Hawash, Marek Perkowski Dec 2011

Application Of Genetic Algorithm For Synthesis Of Large Reversible Circuits Using Covered Set Partitions, Maher Mofeid Hawash, Baker Abdalhaq, Amjad Hawash, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

We present the results of application of Evolutionary Algorithms to the problem of synthesizing quantum circuits which belong to the class of reversible circuits, represented as an input/output mapping vectors. The paper specifically focuses on large quantum circuits where many valid solutions exist in an exponentially inflating search space. Valid solutions represent the set of all input vector permutations (arrangements) which satisfy the circuit specification. The search space for circuits with large number of variables grows exponentially making it impossible to discover the set of optimal solutions. The paper compares three methods for selecting valid solutions of input vector ...


Bottom Topography Mapping Via Nonlinear Data Assimilation, Edward D. Zaron, Marie-Aude Pradal, Patrick D. Miller, Alan F. Blumberg, Nickitas Georgas, Wei Li, Julia Muccino Cornuelle Dec 2011

Bottom Topography Mapping Via Nonlinear Data Assimilation, Edward D. Zaron, Marie-Aude Pradal, Patrick D. Miller, Alan F. Blumberg, Nickitas Georgas, Wei Li, Julia Muccino Cornuelle

Civil and Environmental Engineering Faculty Publications and Presentations

A variational data assimilation method is described for bottom topography mapping in rivers and estuaries using remotely sensed observations of water surface currents. The velocity field and bottom topography are related by the vertically integrated momentum and continuity equations, leading to a nonlinear inverse problem for bottom topography, which is solved using a Picard iteration strategy combined with a nonlinear line search. An illustration of the method is shown for Haverstraw Bay, in the Hudson River, where the known bottom topography is well reconstructed. Once the topography has been estimated, currents and water levels may be forecast. The method makes ...


Future Flooding Impacts On Transportation Infrastructure And Traffic Patterns Resulting From Climate Change, Heejun Chang, Martin Lafrenz, Il-Won Jung, Miguel A. Figliozzi, Rolando Melgoza, David Ruelas, Deena Platman, Cindy Pederson Nov 2011

Future Flooding Impacts On Transportation Infrastructure And Traffic Patterns Resulting From Climate Change, Heejun Chang, Martin Lafrenz, Il-Won Jung, Miguel A. Figliozzi, Rolando Melgoza, David Ruelas, Deena Platman, Cindy Pederson

Geography Faculty Publications and Presentations

This study investigated potential impacts of climate change on travel disruption resulting from road closures in two urban watersheds in the Portland metropolitan area. We used ensemble climate change scenarios, a hydrologic model, stream channel survey, a hydraulic model, and a travel forecast model to develop an integrated impact assessment method. High-resolution climate change scenarios are based on the combinations of two emission scenarios and eight general circulation models. The Precipitation-Runoff Modeling System was calibrated and validated for the period 1988-2006, and simulated for determining the probability of floods from 2020-2049. We surveyed stream cross sections at five road crossings ...


The Relationship Between Vmt And Economic Activity, B. Starr Mcmullen, Nathan Eckstein Nov 2011

The Relationship Between Vmt And Economic Activity, B. Starr Mcmullen, Nathan Eckstein

TREC Final Reports

Vehicle miles traveled (VMT) in the U.S. have exhibited an upward trend over time similar to that observed for gross domestic product (GDP) and personal income (PI). While conventional wisdom suggests that economic growth leads to more driving and thus higher VMT, it is theoretically possible that the causation could also be the other way around. If causation is from VMT to GDP, then legislation such as the Federal Surface Transportation Policy and Planning Act of 2009’s directive to annually reduce national per capita VMT could potentially have an adverse impact on overall economic activity.

This study uses ...


Refining Greenstep: Impacts Of Vehicle Technologies And Its/Operational Improvements On Travel Speed And Fuel Consumption Curves, Kelly Clifton, Alexander Y. Bigazzi Nov 2011

Refining Greenstep: Impacts Of Vehicle Technologies And Its/Operational Improvements On Travel Speed And Fuel Consumption Curves, Kelly Clifton, Alexander Y. Bigazzi

Civil and Environmental Engineering Faculty Publications and Presentations

This report describes analysis undertaken to establish a method for incorporating traffic operations and ITS strategies into the GreenSTEP model. We first discuss operations impacts on fuel economy and delay from the literature. Then, an investigation of delay adjustments in GreenSTEP shows that different methods of representing delay changes lead to similar (and small) impacts on fuel economy. From this result we establish average speed adjustment by congestion level as the preferred method for incorporating delay effects from operations improvements. An investigation of aggregate traffic operations impacts produces estimates of base speeds without operations improvements, maximum speeds with full operational ...


Large–Scale Laboratory Observations Of Wave Forces On A Highway Bridge Superstructure, Chris Bradner, Thomas Schumacher, Daniel Cox, Christopher Higgins Oct 2011

Large–Scale Laboratory Observations Of Wave Forces On A Highway Bridge Superstructure, Chris Bradner, Thomas Schumacher, Daniel Cox, Christopher Higgins

TREC Final Reports

A. Objectives The objectives of this study are to: (1) conduct the first, large-scale physical model study of wave loads on a highway bridge superstructure under realistic wave conditions and bridge geometries, and (2) evaluate the application of existing design formulas developed for deep water, wave-in-deck loading of offshore structures to shallow water, highway bridge geometries. This will aid in our understanding of the dynamic loads by hurricane waves on highway bridge superstructures and assess the accuracy of present methods for safer design of new bridges or retrofit of existing bridges. B. Scope In their 2006 report titled "Wave Forces ...


Bridge Damage Models For Seismic Risk Assessment Of Oregon Highway Network, Peter Dusicka, Jeffery Roberts Oct 2011

Bridge Damage Models For Seismic Risk Assessment Of Oregon Highway Network, Peter Dusicka, Jeffery Roberts

TREC Final Reports

The highway transportation network of the United States relies on the health and integrity of major infrastructure elements such as bridges. Frequently traveled parts of Oregon are within the seismically active Pacific Northwest and many of the bridges were designed and built to lateral demands that were assumed to be less than the current expectation, a deficiency caused by our growing awareness of seismic hazard and our enhanced understanding of the non-linear response of bridges. This vulnerability to damage from earthquakes can result in not only immediate damage, but also in potentially lingering economic impact caused by the disruption to ...


Maintaining Safe, Efficient And Sustainable Intermodal Transport Through The Port Of Portland, David A. Jay, Jiayi Pan Oct 2011

Maintaining Safe, Efficient And Sustainable Intermodal Transport Through The Port Of Portland, David A. Jay, Jiayi Pan

Civil and Environmental Engineering Faculty Publications and Presentations

About $15 billion of freight passes annually through the Lower Columbia River (LCR) navigation channel to reach Portland and Vancouver, where most of it connects with land transport. This commerce plays a vital role in sustaining the regional economy and connecting Oregon to the global economy. The timely connection of truck and rail transport with vessels is vital, especially for export traffic. This link is susceptible to disruption if water depths in the navigation channel are shallower than expected, leading to delays and/or draft limitations. Moreover, ship drafts have increased in recent decades, 25% of the vessels calling in ...


Non-Stationary Internal Tides Observed With Satellite Altimetry, Richard D. Ray, Edward D. Zaron Sep 2011

Non-Stationary Internal Tides Observed With Satellite Altimetry, Richard D. Ray, Edward D. Zaron

Civil and Environmental Engineering Faculty Publications and Presentations

Temporal variability of the internal tide is inferred from a 17-year combined record of Topex/Poseidon and Jason satellite altimeters. A global sampling of along-track sea-surface height wavenumber spectra finds that non-stationary variance is generally 25% or less of the average variance at wavenumbers characteristic of mode-1 tidal internal waves. With some exceptions the non-stationary variance does not exceed 0.25 cm2. The mode-2 signal, where detectable, contains a larger fraction of non-stationary variance, typically 50% or more. Temporal subsetting of the data reveals interannual variability barely significant compared with tidal estimation error from 3-year records. Comparison of summer vs ...


Thirdhand Tobacco Smoke: Emerging Evidence And Arguments For A Multidisciplinary Research Agenda, Georg E. Matt, Penelope J. Quintana, Hugo Destaillats, Lara A. Gundel, Mohamad Sleiman, Brett C. Singer, Peyton Jacob, Jonathan P. Winickoff, Prue Talbot, Suzaynn Schick, Yinsheng Wang, Bo Hang, Manuela Martins-Green, James F. Pankow, Melbourne F. Hovell, Neal L. Benowitz, Virender K. Rehan, Jonathan M. Samet Sep 2011

Thirdhand Tobacco Smoke: Emerging Evidence And Arguments For A Multidisciplinary Research Agenda, Georg E. Matt, Penelope J. Quintana, Hugo Destaillats, Lara A. Gundel, Mohamad Sleiman, Brett C. Singer, Peyton Jacob, Jonathan P. Winickoff, Prue Talbot, Suzaynn Schick, Yinsheng Wang, Bo Hang, Manuela Martins-Green, James F. Pankow, Melbourne F. Hovell, Neal L. Benowitz, Virender K. Rehan, Jonathan M. Samet

Civil and Environmental Engineering Faculty Publications and Presentations

There is broad consensus regarding the health impact of tobacco use and secondhand smoke exposure, yet considerable ambiguity exists about the nature and consequences of thirdhand smoke (THS). We introduce definitions of THS and THS exposure and review recent findings about constituents, indoor sorption-desorption dynamics, and transformations of THS; distribution and persistence of THS in residential settings; implications for pathways of exposure; potential clinical significance and health effects; and behavioral and policy issues that affect and are affected by THS. Physical and chemical transformations of tobacco smoke pollutants take place over time scales ranging from seconds to months and include ...


Determination Of The Electric Field Intensity And Space Charge Density Versus Height Prior To Triggered Lightning, Christopher J. Biagi, Martin A. Uman, Jay Gopalakrishnan, J. D. Hill, Vladimir A. Rakov, T. Ngin, Douglas M. Jordan Aug 2011

Determination Of The Electric Field Intensity And Space Charge Density Versus Height Prior To Triggered Lightning, Christopher J. Biagi, Martin A. Uman, Jay Gopalakrishnan, J. D. Hill, Vladimir A. Rakov, T. Ngin, Douglas M. Jordan

Mathematics and Statistics Faculty Publications and Presentations

We infer the vertical profiles of space charge density and electric field intensity above ground by comparing modeling and measurements of the ground-level electric field changes caused by elevating grounded lightning-triggering wires. The ground-level electric fields at distances of 60 m and 350 m were measured during six wire launches that resulted in triggered lightning. The wires were launched when ground-level electric fields ranged from 3.2 to 7.6 kV m−1 and the triggering heights ranged from 123 to 304 m. From wire launch time to lightning initiation time, the ground-level electric field reduction at 60 m ranged ...


Evaluation Of Safe Routes To School Programs: Qualitative And Quantitative Analysis Of Parental Decision-Making, Lynn Weigand, Noreen Mcdonald Aug 2011

Evaluation Of Safe Routes To School Programs: Qualitative And Quantitative Analysis Of Parental Decision-Making, Lynn Weigand, Noreen Mcdonald

TREC Final Reports

In the United States, walking to school declined from 42% of 5-18 year olds in 1969 to 16% in 20011. The US Department of Transportation has responded to this dramatic decrease by funding the Safe Routes to School program for $612 million in SAFETEA-LU. The program’s funding emphasize infrastructure improvements such as completing sidewalks and adding crosswalks by requiring between 70% and 90% of funding be allocated toward infrastructure. However, recent research shows that 2 of 3 children who currently are driven to school, but live close enough to walk, do so because it is more convenient for parents ...


Bring Your Own Water Treatment System: United States Patent, Evan A. Thomas, Maximilian Gold Aug 2011

Bring Your Own Water Treatment System: United States Patent, Evan A. Thomas, Maximilian Gold

Mechanical and Materials Engineering Faculty Publications and Presentations

A method and apparatus for filtering a fluid is presented. In one embodiment, the apparatus converts contaminated water into water having a lower turbidity and bacterial contamination level than the contaminated water. The apparatus includes a settling unit for at least partially settling a portion of the water; a filter unit having a filtration media; wherein the filtration media comprises sand, anthracite coal, burnt rice husks, diatomaceous earth, gravel, pumice gravel, or combinations thereof; a sanitation unit; wherein the sanitation unit is an ultraviolet disinfection unit; a backwash unit; wherein the settling unit is in fluid communications with the filter ...


Interview With Adam Boesel, Green Micro Gym, 2011 (Audio), Adam Boesel Jul 2011

Interview With Adam Boesel, Green Micro Gym, 2011 (Audio), Adam Boesel

All Sustainability History Project Oral Histories

Interview of Adam Boesel by Teresa Celestine at Green Micro Gym Portland, Oregon on July 29th, 2011.

The interview index is available for download.


Calibration Of Complex System Dynamics Models: A Practioner's Report, Rod Walker, Wayne W. Wakeland Jul 2011

Calibration Of Complex System Dynamics Models: A Practioner's Report, Rod Walker, Wayne W. Wakeland

Wayne W. Wakeland

This paper is not a typical academic paper that is solidly grounded in the literature. Instead, this paper reports practitioner’s experiences in rebuilding and calibrating a very large system dynamics model. A prior version of this model had been in use for over 10 years in an ongoing executive training simulation. That model had never worked correctly in several key areas, requiring the outputs to be manually adjusted by very experienced facilitators during the course of the simulation. The present project rebuilt the system dynamics model, redesigned the parts that weren’t working, and calibrated the resulting model to ...


A System Dynamics Model Of Pharmaceutical Opioids: Medical Use, Diversion, And Nonmedical Use, Teresa D. Schmidt, Wayne W. Wakeland, J. David Haddox Jul 2011

A System Dynamics Model Of Pharmaceutical Opioids: Medical Use, Diversion, And Nonmedical Use, Teresa D. Schmidt, Wayne W. Wakeland, J. David Haddox

Wayne W. Wakeland

Abstract: A dramatic rise in the nonmedical of pharmaceutical opioids has presented the United States with a substantial public health problem. Nonmedical use of prescription pain relievers has become increasingly prevalent in the US over the last two decades, and diversion of medicines obtained by prescription is assumed to be a major source of supply for nonmedical opioid use. Policymakers striving to protect population health by ameliorating the adverse outcomes of nonmedical use of opioid analgesics could benefit from a systems-level model which reflects the complexity of the system and incorporates the full range of available data. To address this ...


Striation-Based Beamforming For Estimating The Waveguide Invariant With Passive Sonar, Lisa M. Zurk, Daniel Rouseff Jul 2011

Striation-Based Beamforming For Estimating The Waveguide Invariant With Passive Sonar, Lisa M. Zurk, Daniel Rouseff

Electrical and Computer Engineering Faculty Publications and Presentations

The waveguide invariant summarizes the pattern of constructive and destructive interference between acoustic modes propagating in the ocean waveguide. For many sonar signal-processing schemes, it is essential to know the correct numerical value for the waveguide invariant. While conventional beamforming can estimate the ratio between the waveguide invariant and the range to the source, it cannot unambiguously separate the two terms. In the present work, striationbased beamforming is developed. It is shown that the striation-based beamformer can be used to produce an estimate for the waveguide invariant that is independent of the range. Simulation results are presented.


Social Innovation Concepts At Nasa: Integrating International Development Challenges And Hands-On Prototyping With Spacecraft Design Training, Leonard Yowell, Evan A. Thomas Jul 2011

Social Innovation Concepts At Nasa: Integrating International Development Challenges And Hands-On Prototyping With Spacecraft Design Training, Leonard Yowell, Evan A. Thomas

Mechanical and Materials Engineering Faculty Publications and Presentations

The NASA Johnson Space Center Social Innovation program has been designed to encourage innovation within the NASA community that benefits both NASA's core mission as well as human needs domestically and internationally. By encouraging internal and external collaboration and providing resources including the new Johnson Space Center "Sandbox" design shop, new innovations are anticipated. Technologies developed for the human exploration of space share similar requirements with appropriate technology for the developing world. The technology goals of keeping people alive in a difficult environment involve addressing requirements for low maintenance and robustness and often include using renewable energy sources. Technologies ...


A System Dynamics Model Of Pharmaceutical Opioids: Medical Use, Diversion, And Nonmedical Use, Teresa Schmidt, Wayne Wakeland, J. David Haddox Jul 2011

A System Dynamics Model Of Pharmaceutical Opioids: Medical Use, Diversion, And Nonmedical Use, Teresa Schmidt, Wayne Wakeland, J. David Haddox

Systems Science Faculty Publications and Presentations

A dramatic rise in the nonmedical of pharmaceutical opioids has presented the United States with a substantial public health problem. Nonmedical use of prescription pain relievers has become increasingly prevalent in the US over the last two decades, and diversion of medicines obtained by prescription is assumed to be a major source of supply for nonmedical opioid use. Policymakers striving to protect population health by ameliorating the adverse outcomes of nonmedical use of opioid analgesics could benefit from a systems-level model which reflects the complexity of the system and incorporates the full range of available data. To address this need ...


Calibration Of Complex System Dynamics Models: A Practioner's Report, Rod Walker, Wayne Wakeland Jul 2011

Calibration Of Complex System Dynamics Models: A Practioner's Report, Rod Walker, Wayne Wakeland

Systems Science Faculty Publications and Presentations

This paper is not a typical academic paper that is solidly grounded in the literature. Instead, this paper reports practitioner’s experiences in rebuilding and calibrating a very large system dynamics model. A prior version of this model had been in use for over 10 years in an ongoing executive training simulation. That model had never worked correctly in several key areas, requiring the outputs to be manually adjusted by very experienced facilitators during the course of the simulation. The present project rebuilt the system dynamics model, redesigned the parts that weren’t working, and calibrated the resulting model to ...


Sustainable Oxygen: A Low Power Approach For Providing Emergency Medical Oxygen For Spacecraft And Hospitals In Developing Countries, Anndee L. Huff, Evan Rhead, Zdenek Zumr, Evan A. Thomas Jul 2011

Sustainable Oxygen: A Low Power Approach For Providing Emergency Medical Oxygen For Spacecraft And Hospitals In Developing Countries, Anndee L. Huff, Evan Rhead, Zdenek Zumr, Evan A. Thomas

Mechanical and Materials Engineering Faculty Publications and Presentations

An oxygen concentrator targeting an 80% reduction in power demand over commercial systems is being developed using a pressure swing adsorption process. This system is targeted for a service interval five times longer than commercial systems, and is tolerant to high humidity environments- the leading cause of device failure in developing countries. This system could provide emergency medical oxygen in a spacecraft without increasing oxygen concentration in the vehicle. Flight surgeons seek this capability, but presently, there is no system that meets power, size, and delivery rate requirements. This type of system is also well suited for medical oxygen in ...


Evolving Machine Morality Strategies Through Multiagent Simulations, David Burke Jun 2011

Evolving Machine Morality Strategies Through Multiagent Simulations, David Burke

Systems Science Friday Noon Seminar Series

There is a general consensus among robotics researchers that the world of the future will be filled with autonomous and semi-autonomous machines. There is less of a consensus, though, on the best approach to instilling a sense of 'machine morality' in these systems so that they will be able to have effective interactions with humans in an increasingly complex world. In my talk, we take a brief look at some existing approaches to computational ethics, and then describe work we've undertaken creating multiagent simulations involving moral decision-making during strategic interactions. In these simulations, agents make choices about whether to ...


Resizable, Scalable, Concurrent Hash Tables, Josh Triplett, Paul E. Mckenney, Jonathan Walpole Jun 2011

Resizable, Scalable, Concurrent Hash Tables, Josh Triplett, Paul E. Mckenney, Jonathan Walpole

Computer Science Faculty Publications and Presentations

We present algorithms for shrinking and expanding a hash table while allowing concurrent, wait-free, linearly scalable lookups. These resize algorithms allow the hash table to maintain constant-time performance as the number of entries grows, and reclaim memory as the number of entries decreases, without delaying or disrupting readers.

We implemented our algorithms in the Linux kernel, to test their performance and scalability. Benchmarks show lookup scalability improved 125x over readerwriter locking, and 56% over the current state-of-the-art for Linux, with no performance degradation for lookups during a resize.

To achieve this performance, this hash table implementation uses a new concurrent ...


Resizable, Scalable, Concurrent Hash Tables Via Relativistic Programming, Josh Triplett, Paul E. Mckenney, Jonathan Walpole Jun 2011

Resizable, Scalable, Concurrent Hash Tables Via Relativistic Programming, Josh Triplett, Paul E. Mckenney, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Presentation focusing on software synchronization, thread locking, transactional memory, and relativistic programming. Hash table algorithms are presented with examples of relativistic list insertion and removal, and related data structures. Existing approaches are compared to new methodologies and future work with relativistic data structures.


Factors For Improved Fish Passage Waterway Construction, David N. Sillars, Hamid Moradkhani, Nicholas Tymvios, Trevor D. Smith Jun 2011

Factors For Improved Fish Passage Waterway Construction, David N. Sillars, Hamid Moradkhani, Nicholas Tymvios, Trevor D. Smith

TREC Final Reports

Streambeds are important fish passageways in Oregon; they provide for the necessary habitats and spawning cycles of a healthy fish population. Oregon state law requires that hydraulic structures located in water properly provide fish passage. Increasingly stringent state and federal regulations apply to these fish passageways, and designers must become more cognizant of conditions over a range of flows to accommodate fish movement and avoid expensive structural failure of these passageways. Fish passage structures are built when roads cross streambeds and may include culverts, or bridges. When these structures are built, the streambeds are re-created using a technique called “roughened ...


Redesign Of Freshman Electrical Engineering Courses For Improved Motivation And Early Introduction Of Design, Phillip Wong, Melinda Holtzman, Branimir Pejcinovic, Malgorzata Chrzanowska-Jeske Jun 2011

Redesign Of Freshman Electrical Engineering Courses For Improved Motivation And Early Introduction Of Design, Phillip Wong, Melinda Holtzman, Branimir Pejcinovic, Malgorzata Chrzanowska-Jeske

Electrical and Computer Engineering Faculty Publications and Presentations

The student experience during the freshman year has been recognized as one of the keys to not only attracting more students into engineering and improving retention, but also to forming some significant attributes of successful engineering graduates. Portland State University is an urban university, and its Electrical and Computer Engineering (ECE) department serves a relatively large and very diverse student population including a large fraction of transfer and part-time students. Traditionally, all engineering disciplines within our Maseeh College of Engineering and Computer Science had a similar freshman year curriculum. The common entry course – Engineering and Applied Science (EAS) 101 – served ...


Assessment Of Statewide Intersection Safety Performance, Christopher M. Monsere, Todd Johnson, Karen Dixon, Jianfei Zheng, Ida Schalkwyk Jun 2011

Assessment Of Statewide Intersection Safety Performance, Christopher M. Monsere, Todd Johnson, Karen Dixon, Jianfei Zheng, Ida Schalkwyk

TREC Final Reports

This report summarizes the results of an analysis of the safety performance of Oregon’s intersections. Following a pilot study, a database of 500 intersections randomly sampled from around the state of Oregon in both urban and rural environments was assembled. These intersections were categorized into eight types based on number of legs (3 and 4), land use (urban or rural) and traffic control (signalized or minor stop-control). These categories were chosen to align with the intersection types in AASHTO’s recently released Highway Safety Manual (HSM). Geometric and traffic control elements were supplemented by compiling crash data and volumes ...


Efficient Support Of Consistent Cyclic Search With Read-Copy-Update And Parallel Updates, Jonathan Walpole, Paul E. Mckenney May 2011

Efficient Support Of Consistent Cyclic Search With Read-Copy-Update And Parallel Updates, Jonathan Walpole, Paul E. Mckenney

Computer Science Faculty Publications and Presentations

A method, system and computer program product for supporting concurrent updates to a shared data element group while preserving group integrity on behalf of one or more readers that are concurrently referencing group data elements without using locks or atomic instructions. Two or more updaters may be invoked to generate new group data elements. Each new data element created by the same up dater is assigned a new generation number that is different than a global generation number associated with the data element group and which allows a reader of the data element group to determine whether the new data ...