Physical Sciences and Mathematics Commons^™

The Relationship Between Precipitation And Temperature Over The Contiguous United States, Weining Zhao, M. A. K. Khalil

Physics Faculty Publications and Presentations

The correlation between monthly total precipitation and monthly mean temperature over the 80-year period from 1905 to 1984 at nearly 1000 stations in the contiguous United States was calculated and analyzed. Both local and field significances were tested by using statistical methods. Areas of both negative and positive precipitation-temperature correlations were found. Over most of the United States, summer precipitation and temperature were negatively correlated, which indicates that warm summers tended to be dryer. This is particularly true in the central and southern Great Plains. The area south of the Great Lakes covering the eastern portion of the Corn Belt …

Existence Of High-Order Superlattices In Orientationally Ordered C_{60}, J. E. Fischer, D. E. Luzzi, K. Kniaź, A. R. Mcghie, D. A. Ricketts-Foot, W. R. Romanow, Gavin B. M. Vaughan, Dayin Li, Allan L. Smith, Robert M. Strongin, M. A. Cichy, Laurent Bard, Amos B. Smith Iii

Chemistry Faculty Publications and Presentations

We correlate the presence or absence of high-order modulated structures in solid C₆₀ with the differential scanning calorimetry signature of the orientational ordering transition and other diagnostic data. We have searched for, but not observed, the 2a face-centered cubic structure recently observed in low-temperature electron and single-crystal x-ray diffraction. We conclude that the intrinsic ground state is the previously reported simple cubic structure [space groupPa3¯, a(14 K)=14.06 Å], and that other structures may be stabilized by defects or impurities.

Coherence Peak And Superconducting Energy Gap In Rb_{3}C_{60} Observed By Muon Spin Relaxation, R. F. Kiefl, W. A. Macfarlane, K. H. Chow, S. Dunsiger, T. L. Duty, T. M. S. Johnston, J. W. Schneider, J. Sonier, Laurent Brard, Robert M. Strongin, J. E. Fischer, Amos B. Smith Iii

Chemistry Faculty Publications and Presentations

Muon spin relaxation resulting from spin exchange scattering of endohedral muonium (μ+e-) with thermal electronic excitations has been observed in the fullerene superconductor Rb₃C₆₀. The temperature dependence of T₁^-1 shows a coherence peak just below T_c and can be fit to the conventional Hebel-Slichter theory for spin relaxation in a superconductor with a broadened BCS density of states. The average energy gap for electronic excitations, Δ/k_B=53(4) K or 2Δ/ k_BT_c=3.6(3), is consistent with the BCS weak coupling limit.

Unusual Thermal Stability Of A Site-Ordered Mc60 Rocksalt Structure (M=K, Rb, Or Cs), Q. Zhu, O. Zhou, J. E. Fischer, Andrew R. Mcghie, W. R. Romanow, Robert M. Strongin, M. A. Cichy, Amos B. Smith Iii

Chemistry Faculty Publications and Presentations

X-ray diffraction and differential scanning calorimetry of M_xC₆₀, with x∼1 and M=K, Rb, or Cs, reveal an unusual T-dependent phase sequence. A low-symmetry ground state is found, while the high-T limit is an ordered rocksalt structure in which only the octahedral sites are occupied. The unusual high-T stability of this ordered phase is attributed to the entropy of molecular orientational disorder and/or thermal disorder of the alkali-metal ions within the octahedral sites. Unique to K_xC₆₀ with x≥1.4, we find at intermediate temperatures an fcc site-disordered lattice gas …

Geochemistry, Alluvial Facies Distribution, Hydrogeology, And Groundwater Quality Of The Dallas-Monmouth Area, Oregon, Rodney R. Caldwell

Dissertations and Theses

The Dallas-Monmouth area, located in the west-central Willamette Valley, Oregon, consists of Tertiary marine and volcanic bedrock units which are locally overlain by alluvium. The occurrence of groundwater with high salinities has forced many rural residents to use public water supplies. Lithologic descriptions from driller's logs, geochemical (INAA), and x-ray diffraction analyses were used to determine alluvial facies distribution, geochemical and clay mineral distinctions among the units, and possible sediment sources. Driller's log, chemical and isotopic analysis, and specific conductance information from wells and springs were used to study the hydrogeologic characteristics of the aquifers and determine the distribution, characteristics, …

Temperature Dependence Of Optical Properties For Amorphous Silicon At Wavelengths Of 632.8 And 752 Nm, P.T. Leung, Nhan Do, Oguz Yavas, Andrew C. Tam, Wing P. Leung, Hee K. Park, Costas P. Grigoropoulos, Johannes Boneberg, Paul Leiderer

Physics Faculty Publications and Presentations

The temperature dependence of the optical properties for amorphous silicon is studied at wavelengths of 632.8 and 752 nm. Both the refractive index and extinction coefficient increase linearly with temperature for 752 nm, while the refractive index decreases and the extinction coefficient increases for 632.8 nm. The rate of increase of the extinction coefficient at 632.8 nm is twice as much as that for 752 nm.

Photodeflection Probing Of The Explosion Of A Liquid Film In Contact With A Solid Heated By Pulsed Excimer Laser Irradiation, P.T. Leung, Nhan Do, Leander Klees, Andrew C. Tam, Wing P. Leung

Physics Faculty Publications and Presentations

The explosion or rapid vaporization of a liquid film on an opaque surface by a pulsed laser is studied experimentally. Using a probe-beam deflection sensing (PDS) scheme, together with a previously developed transmission monitor, the distortion of the PDS signal due to the generation of shock waves by the exploding liquid is investigated. Various liquids, including alcohols and pure water in contact with substrates such as polyimide, amorphous carbon, and silicon, are studied for a wide range of excimer laser fluences. It is concluded that the present PDS technique is highly sensitive to the explosion threshold.

Difficulties Experienced Procedural Programmers Encounter When Transferring To An Object-Oriented Programming Paradigm, Scott Andrew Machaffie

Dissertations and Theses

Experienced procedural programmers seem to have difficulty when transferring from a procedural language to an object-oriented language. The problem is how to assist the experienced procedural programmers to make this shift. The long term goal of this research is to identify areas where programmers have problems and to develop an automated system to help them overcome these difficulties.

This study examines the class designs produced by procedural programmers and the effect of specifications and domain knowledge on class designs. Two types of specifications were used: those written from a procedural point of view which emphasized the functions and those written …

Comprehension Of Literate Programs By Novice And Intermediate Programmers, Christopher Forrest Bertholf

Dissertations and Theses

The studies reported herein compare comprehension of Lit style literate programs to that of traditional modular programs documented by embedded comments. Novice and intermediate programmers participated in three experiments designed to determine the comprehensibility of literate programs written using a language-independent system for abstraction-oriented literate programming compared with programs written using traditional modular programming techniques (traditional modular programs). Programs were written in either the C or FORTRAN programming language. Half of the subjects in each group received a literate program, while the other half received a traditional modular program with embedded documentation. Subjects received a problem specification, input and output …

Shapes Of Venusian "Pancake" Domes Imply Episodic Emplacement And Silicic Composition, Jonathan H. Fink, Nathan T. Bridges, Robert E. Grimm

Geology Faculty Publications and Presentations

The main evidence available for constraining the composition of the large circular "pancake" domes on Venus is their gross morphology. Laboratory simulations using polyethylene glycol show that the height to diameter (aspect) ratios of domes given total volume depend critically on whether their extrusion was continuous or episodic, with more episodes leading to greater cooling and taller domes. Thus without observations of their emplacement, the compositions of venusian domes cannot be uniquely constrained by their morphology. However, by considering a population of 51 venusian domes to sent a sampling of many stages during the growth of domes with comparable histories, …

Hydrodynamic Theory Of Multicomponent Diffusion And Thermal Diffusion In Multitemperature Gas Mixtures, John D. Ramshaw

Physics Faculty Publications and Presentations

A phenomenological theory is developed for multicomponent diffusion, including thermal diffusion, in gas mixtures in which the components may have different temperatures. The theory is based on the hydrodynamic approach of Maxwell and Stefan, as extended and elaborated by Furry [1] and Williams [2]. The present development further extends these earlier treatments to multiple temperatures and multicomponent thermal diffusion. The resulting diffusion fluxes obey generalized Stefan-Maxwell relations which include the effects of ordinary, forced, pressure, and thermal diffusion. When thermal diffusion is neglected, these relations have the same form as the usual single-temperature ones, except that mole fractions are replaced …

A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The Synthesis kernel [21,22,23,27,28] showed that dynamic code generation, software feedback, and fine-grain modular kernel organization are useful implementation techniques for improving the performance of operating system kernels. In addition, and perhaps more importantly, we discovered that there are strong interactions between the techniques. Hence, a careful and systematic combination of the techniques can be very powerful even though each one by itself may have serious limitations. By identifying these interactions we illustrate the problems of applying each technique in isolation to existing kernels. We also highlight the important common under-pinnings of the Synthesis experience and present our ideas on …

On Matching Ann Structure To Problem Domain Structure, George G. Lendaris, Martin Zwick, Karl Mathia

Systems Science Faculty Publications and Presentations

To achieve reduced training time and improved generalization with artificial neural networks (ANN, or NN), it is important to use a reduced complexity NN structure. A "problem" is defined by constraints among the variables describing it. If knowledge about these constraints could be obtained a priori, this could be used to reduce the complexity of the ANN before training it. Systems theory literature contains methods for determining and representing structural aspects of constrained data (these methods are herein called GSM, general systems method). The suggestion here is to use the GSM model of the given data as a pattern for …

Revisiting The Edge Of Chaos: Evolving Cellular Automata To Perform Computations, Melanie Mitchell, Peter T. Hraber, James P. Crutchfield

Computer Science Faculty Publications and Presentations

No abstract provided.

When Will A Genetic Algorithm Outperform Hill-Climbing?, Melanie Mitchell, John H. Holland

Computer Science Faculty Publications and Presentations

In this paper we review some previously published experimental results in which a simple hillclimbing algorithm-Random Mutation Hill-Climbing (RMHC)-significantly outperforms a genetic algorithm on a simple "Royal Road" function. vVe present an analysis of RMHC followed by an analysis of an "idealized" genetic algorithm (IGA) that is in turn significantly faster than RMHC. We isolate the features of the IGA that allow for this speedup, and discuss how these features can be incorporated into a real GA and a fitness landscape, making the GA better approximate the IGA. We use these features to design a modified version of the previously …

Nuclear Magnetic Resonance Study Of Antigen-Antibody Complexes, Including Sequence Specific Assignments And Structural Analysis Of Neurophysin As An Antigen Model, Elisar Jamil Barbar

Dissertations and Theses

The interaction between molecules is essential in a wide range of biological processes. A detailed knowledge of these interactions is necessary for understanding these processes. Among the systems that involve important interactions is the immune system. NMR spectroscopy has a large number of spectral parameters that were used in this work to study antibody-antigen interactions. These same parameters were also used to begin a structural analysis of a medium-sized protein, neurophysin, that has important interactions with neurohormones, and served here as a model antigen. A set of ligands differing in size and charge was designed and used to probe the …

The Morphology Of Lava Flows In Planetary Environments: Predictions From Analog Experiments, Ross W. Griffiths, Jonathan H. Fink

Geology Faculty Publications and Presentations

The rates of surface cooling and lateral spreading are evaluated for lava flows on the surface of Earth, Venus, Mars, the Moon, and 10. Differences between the flow morphologies expected in these environments are then predicted under the assumption that the results of recent laboratory simulations oflavas using wax extruded beneath cold water (Fink and Griffiths, 1990) can be carried over. These experiments involved the spreading of viscous liquid under gravity in the presence of a solidifying surface crust and revealed a set of four distinct surface morphologies. Transitions from one morphology to the next occurred in a well-defined sequence …

Solidification And Morphology Of Submarine Lavas: A Dependence On Extrusion Rate, Ross W. Griffiths, Jonathan H. Fink

Geology Faculty Publications and Presentations

The results of recent laboratory experiments with wax extruded beneath relatively cold water may be extrapolated to predict the surface morphology of submarine lavas as a function of the extrusion rate and melt vIscosity. The experiments with solidifying wax indicated that the surface morphology was controlled by a single parameter, the ratio of the time taken for the surface to solidify, and a time scale for lateral flow. For submarine basalts a solution of the cooling problem (which is dominated by conduction in the lava but convective heat transfer in the water) and estimates of lava viscosities place this parameter …

The Effects Of Rapid Heating And Cooling On The Composition, Structure, And Superconducting Properties Of Bi-Sr-Ca-Cu-O Compounds, Qing Duan

Dissertations and Theses

Bulk and thin film samples of Bi₂₋[subscript x]Pb[subscript x]Sr₂Ca₂Cu₃O[subscript y] compounds were prepared by suitable methods. The thin film and bulk samples were exposed to argon gas at temperatures of about 2000 °C and pressures of about 300 atm. in a ballistic compressor (BC) and then cooled at a rate of about 10⁵ °C/sec. The samples before and after this treatment were examined and compared using a transmission electron microscope (TEM), a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS) , and an x-ray diffractometer (XRD). Resistance and magnetic susceptibility measurements were made to determine changes in superconducting temperature …

Explosion Of A Liquid Film In Contact With A Pulse-Heated Solid Surface Detected By The Probe-Beam Deflection Method, P.T. Leung, Andrew C. Tam, Nhan Do, Leander Klees, Wing P. Leung

Physics Faculty Publications and Presentations

The threshold for explosive vaporization of a liquid layer on an opaque solid surface heated by an ultraviolet excimer pulsed laser is studied by a photoacoustic probe-beam deflection method. The probe beam traverses the liquid in the vicinity of the laser-heated liquid-solid interface. Below the explosion threshold, photoacoustic generation in the solid occurs only through a thermoelastic mechanism, which results mainly in shear waves that do not couple well into the liquid. Above the explosion threshold, photoacoustic pulses in the solid are also produced by explosive recoil, hence producing longitudinal pulses in the solid that couple well into the liquid …

Correction Of Chromatic Aberration With An Electron Mirror, Michael Stewart Mauck

Dissertations and Theses

The theoretical basis for using electron mirrors as correctors of chromatic aberration is presented and an experimental verification of correction of chromatic aberration is demonstrated. A hyperbolic electrostatic electron mirror operating in its converging range and at unity magnification was used as a corrector. A novel separating system with deflections taking place at image planes was developed to implement the mirror without impairing the resolution. Correction was demonstrated in an electron optical probe system. The chromatic aberration was measured by means of the shadows cast by a fine mesh placed near the final image. The experimental method and equipment are …

Dynamic Nmr Study Of Bond Rotational Activation Parameters In Micelles, Dietmar A. Leitner

Dissertations and Theses

The behavior of surfactants in solution has been and still is of scientific, technological, and industrial interest. The micelle forming compounds sodium N-( octyloxycarbonyl)sarcosinate (NaOcSarc), and sodium N-(decyloxycarbonyl)sarcosinate (NaDecSarc) show in aqueous solution two ¹H NMR N-methyl peaks arising from a possible cis- or trans-conformation. The relative population of the N-methyl peaks depends mostly on the concentration of surfactant indicating micelle formation. Upon heating the two peaks start to coalesce and finally appear as one single peak. The temperature range in which this phenomenon occurs is from 25°C to 65°C. The primary interest of this study was to determine …

Compiling Ace For Distributed-Memory Machines, Jun Song

Dissertations and Theses

Distributed-memory machines offer a very high level of performance, flexibility and scalability. But the memory organization of this kind of machine determines that processes on different processors must communicate explicitly by sending and receiving messages. As a result, the programmer faces the enormously difficult task of detailed planning of algorithm-irrelevant, low-level communication issues. This level of programming resembles writing assembly programs for a sequential machine.

ACE is a message-passing language with abstract communication statements. It was defined by Dr. Jingke Li at Portland State University. The communication in ACE is still explicit, but it is abstracted to a higher level. …

A Technique For The Evaluation Of Double Excitation Of Atoms By Fast Protons And Antiprotons, Jack C. Straton, James H. Mcguire, Zheng Chen

Physics Faculty Publications and Presentations

A technique for evaluating cross sections for two-electron excitation in collisions of atoms with fast particles of charge ZP is presented. The atomic wave function is approximated by a sum of pair products of one-electron wave functions, with the coefficients chosen by diagonalizing the fully correlated twoelectron Hamiltonian. Thus spatial correlation is included in both the asymptotic and scattering regions by using these configuration-interaction (Cl) wave functions for initial, intermediate, and final states. Use of CI wave function also allows the first-order contributions to be expressed in closed, analytical form. Both the energy-conserving and energy-nonconserving parts of the second-order amplitude …

Binary Mixtures Near Surfaces, Patrick Dunn

Dissertations and Theses

This paper presents an approach to modeling a binary mixture near a surf ace. The approach used is based on statistical mechanics. The Cluster Variation (CV) method is used to solve an Ising-like model with a cluster size of two (neighboring lattice points). The free energy of the system is expressed in terms of the probabilities of occurrences of particular clusters. The CV method is first developed for a homogeneous system which leads to a set of three non-linear partial differential equations. The surface boundary is then introduced and the CV method is developed for this system which leads to …

Flux Trapping In Superconducting Pellets, Andreas Straub

Dissertations and Theses

This research concerns the effects on samples of nominal composition Bi_1.8Pb_0.2Sr₂Ca₂Cu₃O_y which were exposed to hot, dense argon in a ballistic compressor.

The investigations were concentrated on two specimens which were exposed to hot, dense argon at about 1800 K (peak pressure 330 atm) and 1500 K (peak pressure 230 atm), respectively. Sample Bi #1 showed a completely melted surface structure after triple exposure in the ballistic compressor at 1800 K while the surface of sample Bi #7 was just partly melted after double exposure at 1500 K.

Changes …

Textural Constraints On Effusive Silicic Volcanism: Beyond The Permeable Foam Model, Jonathan H. Fink, Steven W. Anderson, Curtis R. Manley

Geology Faculty Publications and Presentations

Transitions between explosive and effusive phases of silicic volcanic eruptions have been related either to stratification of volatiles in the source magma body or to the loss of volatiles through the permeable host rock of the conduit. One way to distinguish between these two models is to map and analyze the vesicular and glassy textures found in silicic lava flows. In this paper we present textural observations and isotopic evidence from active and Recent silicic lava flows which show thaI at least some vesiculation occurs during surface advance of extrusions, after magma has reached the earth's surface. This view is …

Fage Measurements Of Tropospheric Ho With Measurements And Model Of Interferences, Thomas M. Hard, A. A. Mehrabzadeh, C. Y. Chan, Robert J. O'Brien

Environmental Science and Management Faculty Publications and Presentations

Ambient HO measurements by low-pressure laser-excited fluorescence with chemical modulation, and supporting ozone and water-vapor data, are presented for periods in May and August 1987. The observed peak daytime ambient HO concentrations in Oregon are in the range (2.5 to 8) times106 molecules cm⁻³ and show small negative offsets due to photochemical interference. Direct measurements of the interference at fixed [O₃] give the dependence on ambient [H₂O] and on the modulating reagent [isobutane]. At ambient [O₃]=30 p.p.b. and 10 torr H₂O, with excitation and detection at a total pressure of 4 torr, the net interference is equal to [HO]=-1.3times10⁶ molecule …

Diurnal Ho₂ Cycles At Clean Air And Urban Sites In The Troposphere, Thomas M. Hard, C. Y. Chan, A. A. Mehrabzadeh, Robert J. O'Brien

Environmental Science and Management Faculty Publications and Presentations

HO₂ concentrations have been determined at two Oregon sites for continuous periods of 36 to 48 hours, using fluorescence assay with gas expansion. At the sea level coastal site (45degN 124degW), NNW winds prevailed during daytime, and a point measurement of very low total nonmethane hydrocarbon concentration indicated the presence of remote tropospheric air of oceanic origin. At the urban site, HO₂ was determined during moderately low ozone pollution levels. At both sites, maximum daily [HO₂] was in the range of 1-2times10⁸ cm⁻³ under clear-sky conditions, with an estimated overall uncertainty of 40%.

Transmission Studies Of Explosive Vaporization Of A Transparent Liquid Film On An Opaque Solid Surface Induced By Excimer-Laser-Pulsed Irradiation, P.T. Leung, Nhan Do, Leander Klees, Wing P. Leung, Frank Tong

Physics Faculty Publications and Presentations

Examines the dynamics of the explosion of a liquid film by an ultraviolet excimer pulsed laser studied experimentally on top of an amorphous silicon film deposited on fused quartz. Background on thermal physics of superheated pure or mixed liquids; Techniques for surface temperature measurement; Experimental of probe laser and pulsed excimer laser.