Digital Commons Network^™

A Comparison Of Training Algorithms For Dhp Adaptive Critic Neuro-Control, George G. Lendaris, Thaddeus T. Shannon, Andres Rustan

Complex Systems Faculty Publications and Presentations

A variety of alternate training strategies for implementing the Dual Heuristic Programming (DHP) method of approximate dynamic programming in the neuro-control context are explored. The DHP method of controller training has been successfully demonstrated by a number of authors on a variety of control problems in recent years, but no unified view of the implementation details of the method has yet emerged. A number of options are here described for sequencing the training of the Controller and Critic networks in DHP implementations. Results are given about their relative efficiency and the quality of the resulting controllers for two benchmark control …

Work In Progress: Automating Proportion/Period Scheduling, David Steere, Jonathan Walpole, Calton Pu

Computer Science Faculty Publications and Presentations

The recent effort to define middleware capable of supporting real-time applications creates the opportunity to raise the level of abstraction presented to the programmer. We propose that proportion/period is a better abstraction for specifying resource needs and allocation than priorities. We are currently investigating techniques to address some issues that are restricting use of proportion/period scheduling to research real-time prototypes. In particular, we are investigating techniques to automate the task of selecting proportion and period, and that allow proportion/period to incorporate job importance under overload conditions.

Investigation Of Image Feature Extraction By A Genetic Algorithm, Steven P. Brumby, James P. Theiler, Simon J. Perkins, Neal R. Harvey, John J. Szymanski, Jeffrey J. Bloch, Melanie Mitchell

Computer Science Faculty Publications and Presentations

We describe the implementation and performance of a genetic algorithm which generates image feature extraction algorithms for remote sensing applications. We describe our basis set of primitive image operators and present our chromosomal representation of a complete algorithm. Our initial application has been geospatial feature extraction using publicly available multi-spectral aerial-photography data sets. We present the preliminary results of our analysis of the efficiency of the classic genetic operations of crossover and mutation for our application, and discuss our choice of evolutionary control parameters. We exhibit some of our evolved algorithms, and discuss possible avenues for future progress.

A New Numerical Model Of Coupled Inland Ice Sheet, Ice Stream, And Ice Shelf Flow And Its Application To The West Antarctic Ice Sheet, Christina L. Hulbe, D. R. Macayeal

Geology Faculty Publications and Presentations

We have developed a dynamic/thermodynamic finite element numerical model that couples inland ice sheet, ice stream, and ice shelf dynamics. This new model stands apart from other whole ice sheet models in its explicit treatment of ice stream flow. Additionally, the model accounts for both horizontal and vertical advection and diffusion of temperature in the flowing ice. In present day simulations of the West Antarctic Ice Sheet (WAIS), modeled ice velocity agrees well with observed ice flow. In particular, the model reproduces the pattern of speed variation across ice streams although the continuous downstream speed up of ice flow cannot …

Faculty Senate Monthly Packet October 1999, Portland State University Faculty Senate

Faculty Senate Monthly Packets

The October 1999 Monthly packet includes the October agenda and appendices and the Faculty Senate minutes and attachments from the meeting held June 1999.

Human History As A Natural Science. Review Of: Guns, Germs, And Steel: The Fates Of Human Societies By Jared Diamond, Robert Costanza

Institute for Sustainable Solutions Publications and Presentations

Book review of Guns, Germs, and Steel: The Fates of Human Societies. Jared Diamond. W. W. Norton, New York, 1997.

Feedback, Accountability, And The Standards-Based System, Dannelle D. Stevens

Education Faculty Publications and Presentations

The standards-based system provides feedback and accountability, and, more importantly, it challenges educators to re-examine basic assumptions about teaching, learning, and schooling. These assumptions are changing as a result of the standards-based system, and this has positively affected practices in the classroom.

Implementation And Performance Of Error Correction Codes For High-Speed Computer Networks, Jochen Spengler

Dissertations and Theses

During the transmission of data there is always a possibility that errors occur and some pieces are modified. If the receiver detects an error it either sends a request for retransmission or, like in networks using Ethernet, it does not send an acknowledgment for the erroneous frame. In this case the sender waits a certain time and retransmits the frame. With the development of faster computer networking hardware and the need for more real-time applications, these errors have become a major concern. Long retransmission latencies and the need for large memories for buffering drive the development of more reliable network …

An Informal Review Of The Crisis Of Global Capitalism: A Letter To George Soros, Martin Zwick

Complex Systems Faculty Publications and Presentations

The author presents a review and critique of George Soros' The Crisis in Global Capiltalism, published by Public Affairs press in 1998, and attempts to draw attention to systems-theoretic ideas that pertain to the arguments proposed by Soros.

Capillary Surfaces In An Exotic Container: Results From Space Experiments, Paul Concus, Robert Finn, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

Experimental results from the Interface Configuration Experiment (ICE) performed aboard the Space Shuttle and the Mir Space Station are reported. The experiment concerns fluid interfaces in certain ‘exotic’ containers in a low-gravity environment. These containers are rotationally symmetric and have the property that for given contact angle and liquid volume, a continuum of distinct rotationally symmetric equilibrium configurations can appear, all of which have the same mechanical energy. These symmetric equilibrium configurations are unstable, in that deformations that are not rotationally symmetric can be shown mathematically to yield configurations with lower energy. It is found experimentally, in confirmation of mathematical …

Anomalous Low-Temperature And High-Field Magnetoresistance In The Organic Superconductor Β″-(Bedt-Ttf)2sf5ch2cf2so3, F. Zuo, X. Su, P. Zhang, J. S. Brooks, J. Wosnitza, J. A. Schlueter, Jack M. Williams, P. G. Nixon, Rolf Walter Winter, Gary L. Gard

Chemistry Faculty Publications and Presentations

We report direct observations of anomalous magnetic-field and temperature dependences of the Shubnikov–de Haas oscillations in the organic superconductor β″-(BEDT-TTF)₂SF₅CH₂CF₂SO₃. Unlike other BEDT-TTF based organic superconductors, a nonmetallic temperature dependence of the background magnetoresistance is clearly observed. It is speculated that the nonmetallic behavior may arise from a partial nesting of the open orbits, similar to the field-induced density wave in the quasi-one-dimensional systems or a charge localization. The analysis of the magnetoresistance oscillations are found to deviate from the conventional Lifshitz-Kosevich description at high field and low temperatures. [S0163-1829(99)05433-8]

Addendum: "Bethe Stopping-Power Theory For Heavy-Target Atoms", P.T. Leung

Physics Faculty Publications and Presentations

Our previous result on the correction of the Bethe stopping power theory for heavy target elements is amended, with the application of a more consistent version of the semirelativistic Bethe sum rule worked out recently [Phys. Rev. A 57, 4994 (1998)]. This correction is found to be significant for high-Z target atoms and relatively high-energy incident particles.

Portland State Magazine, Portland State University. Office Of University Communications

Portland State Magazine

PSU’s alumni magazine, published 2-3 times a year. In this issue: The Willamette River can be made safe to drink, say researchers, but who wants to?; the technology for a super fast, home, Internet connection is brand new, in demand, and taught at Portland State; new help is finding the right word and the right career in writing; performing jazz drives this alumna to local night spots and to the recording studio; alumni and faculty support a program that links at-risk children with long-term mentors; and more.

Qos Scalability For Streamed Media Delivery, Charles Krasic, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Applications with real-rate progress requirements, such as mediastreaming systems, are difficult to deploy in shared heterogenous environments such as the Internet. On the Internet, mediastreaming systems must be capable of trading off resource requirements against the quality of the media streams they deliver, in order to match wide-ranging dynamic variations in bandwidth between servers and clients. Since quality requirements tend to be user- and task-specific, mechanisms for capturing quality of service requirements and mapping them to appropriate resource-level adaptation policies are required. In this paper, we describe a general approach for automatically mapping user-level quality of service specifications onto resource …

Fine-Grain Period Adaptation In Soft Real-Time Environments, David Steere, Joshua Gruenberg, Dylan Mcnamee, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Reservation-based scheduling delivers a proportion of the CPU to jobs over a period of time. In this paper we argue that automatically determining and assigning this period is both possible and useful in general purpose soft real-time environments such as personal computers and information appliances. The goal of period adaptation is to select the period over which a job is guaranteed to receive its portion of the CPU dynamically and automatically. The choice of period represents a trade-off between the amount of jitter observed by the job and the overall efficiency of the system. Secondary effects of period include quantization …

Modeling Macrophytes Of The Columbia Slough, Oregon, Chris Berger, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

The Columbia Slough is a tidally influenced freshwater system of wetlands, channels, and lakes located within the Portland, Oregon metropolitan area at the confluence of the Willamette and Columbia Rivers. It is a eutrophic water body susceptible to algae blooms and crashes and periods of high pH which violate water quality standards. High nutrient loads from groundwater principally controls algae productivity. Past structural changes to the Columbia Slough have included filling of wetlands and lakes and the construction of levees, dikes, culverts and irrigation channels. These changes have altered the natural flow dynamics creating an environment more conducive to eutrophication. …

Optical Properties Of Β″-(Et)2sf5ch2cf2so3: A Layered Molecular Superconductor With Large Discrete Counterions, J. Dong, J. L. Musfeldt, J. A. Schlueter, Jack M. Williams, P. G. Nixon, Rolf Walter Winter, Gary L. Gard

Chemistry Faculty Publications and Presentations

We report the polarized infrared and optical reflectance of β″-(ET)₂SF₅CH₂CF₂SO₃ as a function of temperature. This fully organic superconductor displays weakly metallic behavior over the entire temperature range of our investigation. The electronic properties present several unusual features including the lack of a conventional free carrier (Drude) response at low temperature, infrared localization phenomena, and an unexpected temperature dependence of the oscillator strength. Similar behavior is observed in other β and β″ superconductors above Tc, suggesting that this class of compounds is very close to a metal→insulator transition where electronic correlations are important and the Drude response carries very little …

Simple Model For Linear And Nonlinear Mixing At Unstable Fluid Interfaces In Spherical Geometry, John D. Ramshaw

Physics Faculty Publications and Presentations

A simple model was recently described for predicting linear and nonlinear mixing at an unstable planar fluid interface subjected to an arbitrary time-dependent variable acceleration history [J. D. Ramshaw, Phys. Rev. E 58, 5834 (1998)]. Here we present an analogous model for describing the mixing of two adjacent spherical fluid shells of different density resulting from an arbitrary time-dependent mean interface radius R(t). As in the planar case, the model is based on a heuristic expression for the kinetic energy of the system. This expression is based on that for the kinetic energy of a linearly perturbed interface, but with …

One Giant Leap. Review Of: Consilience: The Unity Of Knowledge By Edward O. Wilson, Robert Costanza

Institute for Sustainable Solutions Publications and Presentations

Book review of Consilience: The Unity of Knowledge. Edward O. Wilson. Knopf, New York, 1998.

Comment On "Relativistic Correction Of The Generalized Oscillator Strength Sum Rules", P.T. Leung, Scott M. Cohen

Physics Faculty Publications and Presentations

Romero and Aucar [Phys. Rev. A 57, 2212 (1998)] have found a vanishing result for the relativistic correction to the dipole sum rule ∆S1 for a one-electron system. They have given a result for the dipole sum rule ∆S2 as well. We argue that these results are both incorrect and show explicitly that their approach yields a nonvanishing result for ∆S1. The corrected result is in agreement with that which we have obtained in a recent paper, in which we present explicit expressions for ∆S1, ∆S2, and several other more general sum rules.

Faculty Senate Monthly Packet June 1999, Portland State University Faculty Senate

Faculty Senate Monthly Packets

The June 1999 Monthly packet includes the June agenda and appendices and the Faculty Senate minutes and attachments from the meeting held May 1999.

Near-Field Fluorescence Microscopy Based On Two-Photon Excitation With Metal Tips, Erik J. Sánchez, Lukas Novotny, X. Sunney Xie

Physics Faculty Publications and Presentations

We present a new scheme for near-field fluorescence imaging using a metal tip illuminated with femtosecond laser pulses of proper polarization. The strongly enhanced electric field at the metal tip (ap15 nm end diameter) results in a localized excitation source for molecular fluorescence. Excitation of the sample via two-photon absorption provides good image contrast due to the quadratic intensity dependence. The spatial resolution is shown to be better than that of the conventional aperture technique. We used the technique to image fragments of photosynthetic membranes, as well as j-aggregates with spatial resolutions on the order of 20 nm.

Faculty Senate Monthly Packet May 1999, Portland State University Faculty Senate

Faculty Senate Monthly Packets

The May 1999 Monthly packet includes the May agenda and appendices and the Faculty Senate minutes and attachments from the meeting held April 1999.

Measurement Of Free Radicals Oh And Ho₂ In Los Angeles Smog, Linda Acha George, Thomas M. Hard, Robert J. O'Brien

Environmental Science and Management Faculty Publications and Presentations

Atmospheric free radicals hydroxyl and hydroperoxyl (OH and HO₂, collectively HOᵪ ) are the catalysts that cause secondary or photochemical air pollution. Chemical mechanisms for oxidant and acid formation, on which expensive air pollution control strategies are based, must accurately predict these radical concentrations. We have used the fluorescence assay with gas expansion (FAGE) technique to carry out the first simultaneous, in situ measurements of these two radicals in highly polluted air during the Los Angeles Free Radical Experiment. A complete suite of ancillary measurements was also made, including speciated hydrocarbons, carbon monoxide, aldehydes, nitric oxide, nitrogen dioxide, and ozone …

Natural Emissions Of Chlorine-Containing Gases: Reactive Chlorine Emissions Inventory, M. A. K. Khalil, R. M. Moore, D. B. Harper, J. M. Lobert, D. J. Erickson, V. Koropalov, W. T. Sturges, W. C. Keene

Physics Faculty Publications and Presentations

Although there are many chlorine-containing trace gases in the atmosphere, only those with atmospheric lifetimes of 2 years or fewer appear to have significant natural sources. The most abundant of these gases are methyl chloride, chloroform, dichloromethane, perchloroethylene, and trichloroethylene. Methyl chloride represents about 540 parts per trillion by volume (pptv) Cl, while the others together amount to about 120 pptv Cl. For methyl chloride and chloroform, both oceanic and land-based natural emissions have been identified. For the other gases, there is evidence of oceanic emissions, but the roles of the soils and land are not known and have not …

Benefit Analysis Of Igbt Power Device Simulation Modeling, Michael P. Gallaher, Sheila A. Martin

Institute of Metropolitan Studies Publications

The National Institute of Standards and Technology’s Electronic and Electrical Engineering Laboratory (NIST/EEEL) program supports the development of mathematical models for several classes of semiconductor devices. This study presents the results from a microeconomic impact assessment of the development of mathematical models for the design of insulated-gate bipolar transistor (IGBT) semiconductor power devices. NIST/EEEL’s IGBT mathematical modeling program (referred to as the NIST IGBT modeling program) has led to significant economic benefits. These benefits include: improvements in R&D efficiency, decreases in transaction costs, decreases in production costs, and improvements in product quality.

NIST’s activities have affected software companies, IGBT device …

Faculty Senate Monthly Packet April 1999, Portland State University Faculty Senate

Faculty Senate Monthly Packets

The April 1999 Monthly packet includes the April agenda and appendices and the Faculty Senate minutes and attachments from the meeting held March 1999.

Acorn Foraging As A Means To Explore Human Energetics And Forge Connections To Local Forests, Jeffrey J. Gerwing, Pamela Lockwood, Christopher Uhl

Environmental Science and Management Faculty Publications and Presentations

Jeffrey Gerwing, Pamela Lockwood, and Christopher Uhl describe a rather unusual ecology laboratory/field exercise that utilizes abundant oak habitats of central Pennsylvania. For those readers not blessed with an abundant supply of oaks nearby, perhaps other species could be substituted. The exercise is unusual in two ways. It offers a new undergraduate ecology activity, and it offers opportunities for students to relate other disciplines to their science course.

In "the good old days" of higher education each discipline offered its menu of courses and expected students to make appropriate connections among the courses of their major, minor, and general education. …

Measurement Of The Cross-Sectional Area Of The Nasal Passages Of Nine Species Of Modern Odontoceti With Implications For Comparative Physiology And The Paleophysiology Of The Dinosauria, Eric Paul Katz

Dissertations and Theses

In search of evidence for or against the endothermic dinosaur hypothesis, a recent study by Ruben et al. (1996) revealed that endotherms tend to have larger nasal cross-sectional areas than ectotherms of the same mass. The reason offered for this observation was that larger nasal passages are needed to house the complex respiratory turbinates possessed by endotherms. Whales were excluded from the study on the grounds that they have no nasal turbinates. In the present study, the cross-sectional area of the nasal passages of nine species of Odontoceti were measured by the use of latex casts. The regression of log …

Globalization And The Sustainability Of Human Health: An Ecological Perspective, Robert Costanza, A. J. Mcmichael, Bert Bolin, Gretchen C. Daily, Carl Folke, Kerstin Lindahl-Kiessling, Elisabet Lindgren, Bo Niklasson

Institute for Sustainable Solutions Publications and Presentations

The last half-century has seen momentous and accelerating changes in humankind's economic activities, political relations, and social and demographic profile. A prominent feature of this change is the increasing scale of human impact on Earth's natural biophysical systems: the climate system, stratospheric ozone, biodiversity, terrestrial and marine food-producing ecosystems, and the great cycles of water, nitrogen, and sulfur (Meyer 1996, Vitousek et al. 1997). These systems sustain the conditions on which life depends, and their weakening may therefore have profound long-term implications for human population health (McMichael 1993, Last 1997).