Physical Sciences and Mathematics Commons^™

The Role Of Small-Impact-Parameter Electron-Loss Processes On Ion Temperatures Measured By Active-Beam Plasma Diagnostics, A. J.H. Donné, F. J. De Heer, Ronald E. Olson

Physics Faculty Research & Creative Works

The shape of the energy distribution of scattered particles in an active beam scattering experiment can be influenced considerably by the presence of highly charged impurity ions in the plasma. In this work it is shown theoretically that multiply charged impurities have only a small effect on the scattering distribution at low energies (/amu) and at high energies (>75 keV/amu). The effect of the impurities is the most pronounced for energies close to 50 keV/amu. The results of the calculations are in good agreement with experimental results at various energies. Extrapolation to higher beam energies leads to the conclusion …

Development Of An Expert System To Convert Knowledge-Based Geological Engineering Systems Into Fortran, Jill J. Cress, Ralph W. Wilkerson

Computer Science Technical Reports

A knowledge-based geographic information system (KBGIS) for geological engineering map (GEM) production was developed in GoldWorks, an expert system development shell. GoldWorks allows the geological engineer to develop a rule base for a GEM application. Implementation of the resultant rule base produced a valid GEM, but took too much time. This proved that knowledge-based GEM production was possible but in GoldWorks implementation failed as a practical production system. To solve this problem, a Conversion Expert System was developed which accepted, as input, a KBGIS and produced, as output, the equivalent Fortran code. This allowed the engineer to utilize GoldWorks for …

The Directed Steiner Problem On Graphs: A Simulated Annealing Approach, Lawrence Joseph Osborne, Billy E. Gillett

Computer Science Technical Reports

The well-known Steiner Problem on Graphs is an NP-complete problem for which there are many heuristic and exact algorithms that are deterministic. In this dissertation a new approach to the directed version of this problem is made by applying the ideas of statistical mechanics through the use of the method of simulated annealing. A version of annealing is developed for the Directed Steiner Problem and compared with one of the best general annealing schemes. Then a comparison is made between simulated annealing and the traditional branch and bound technique. The dual ascent algorithm of Richard T. Wong is used to …

Study Of The Dependence Of The Electron Emission Spectra On The Projectile Charge In H⁺, He2++He Collisions, C. O. Reinhold, Ronald E. Olson

Physics Faculty Research & Creative Works

The classical trajectory Monte Carlo method (CTMC) has been used to calculate doubly differential ionized-electron cross sections for the impact of He2+ and H+ on He at collision energies of 50 and 100 keV amu-1. The results exhibit the capture to the continuum peak and agree in both shape and magnitude with experimental data. The dependence of the cross sections on the projectile charge ZP is analyzed and it is found to be very asymmetric with regard to the capture to the continuum peak. This behavior is in agreement with very recent experimental data. Large deviations from the Z2P scaling …

Low- And High-Relief Leduc Formation Reefs: A Seismic Analysis, Neil Lennart Anderson, Robert James Sidford Brown, Ronald C. Hinds

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Leduc reefs have grown to widely varying heights and aereal extents along the Rimbey-Meadowbrook trend of central Alberta, resulting in significantly different seismic signatures. Three examples considered in this paper include two high-relief or full reefs from the Leduc-Woodbend field, an atoll and a pinnacle, each around 200 m in height but differing greatly in areal extent, about 100 km² for the atoll and 1 km² for the pinnacle. The third example, a low-relief or basalt reef from the Morinville field, is about 100 m high and 1 km² in areal extent.

The Leduc-Woodbend and Morinville reefs …

Analysis Of Experimental Nucleation Data For Silver And Sio Using Scaled Nucleation Theory, Barbara N. Hale, Paul R. Kemper, Joseph A. Nuth

Physics Faculty Research & Creative Works

The experimental vapor phase nucleation data of Nuth et al., for silver [J. A. Nuth, K. A. Donnelly, B. Donn, and L. U. Lilleleht, J. Chem. Phys. 77, 2639 (1982)] and SiO [J. A. Nuth and B. Donn, J. Chem. Phys. 85, 1116 (1986)] are reanalyzed using a scaled model for homogeneous nucleation [B. N. Hale, Phys. Rev. A 33, 4156 (1986)]. The approximation is made that the vapor pressure at the nucleation site is not diminished significantly from that at the source (crucible). It is found that the data for ln S have a temperature dependence consistent with the …

Quantum Transport In The Presence Of Random Traps, John Wm Edwards, Paul Ernest Parris

Physics Faculty Research & Creative Works

We calculate the asymptotic decay of a quantum particle moving in a d-dimensional medium doped with randomly placed trapping impurities, focusing on contributions from slowly decaying long-wavelength modes centered in large compact regions devoid of traps. By averaging the decay over the statistical distribution associated with these regions we find that the survival probability, P(t) ~exp(-At^d/(d+3)), decays more slowly in any dimension than for diffusive transport.

One-Dimensional Quantum Transport In The Presence Of Traps, Paul Ernest Parris

Physics Faculty Research & Creative Works

A study is made of the survival probability P(t) for a quantum particle moving coherently on an ordered one-dimensional chain containing randomly placed irreversible traps in concentration q. We consider two separate models of the trapping process, focusing on the long-time limit of each. In the first model, intended to describe substitutional traps, the trapping impurities act as disruptive absorbing barriers which prevent further motion along the chain. For this model it is shown that -ln[P(t)]1/4t^1/4. The second model is intended to describe interstitial trapping impurities which do not disrupt the transport. It is argued for this case …

Full Optical Potential For The Electron-Hydrogen Entrance Channel, Igor Bray, Don H. Madison, Ian E. Mccarthy

Physics Faculty Research & Creative Works

Differential and total elastic and total reaction cross sections are calculated for electron-hydrogen scattering at 30, 100, and 400 eV using an ab initio optical potential that treats bound and continuum nonelastic channels in the distorted-wave Born approximation. Multichannel and partial wave expansions are carried out to numerical convergence. Convergence criteria and quadratures for the continuum-energy integration are chosen for 1% overall accuracy. Results are compared with experiment and less detailed calculations.

Resonant Dielectronic And Direct Excitation In Crystal Channels, Sheldon Datz, Charles Randy Vane, Peter F. Dittner, J. P. Giese, J. C. Gomez Del Campo, N. L. Jones, Herbert F. Krause, Philip D. Miller, Michael Schulz, Harald Schone, Thomas M. Rosseel

Physics Faculty Research & Creative Works

We have observed dielectronic and direct excitation of H-like S¹⁵⁺ and Ca¹⁹⁺ and He-like Ti²⁰⁺ ions in silicon channels caused by collision with weakly bound target electrons which behave as a free-electron gas. As in vacuo, relaxation of the doubly excited states can occur radiatively leading to ions of decreased charge, but in a crystal channel collisional effects can cause double ionization. The effects are seen in both the x-ray yields and charge-state fractions, and, in the case of Ti²⁰⁺, in charge-state x-ray coincidences.

Single And Double-Electron Removal From H− In Energetic Collisions With Multiply-Charged Argon Ions, F. Melchert, W. Debus, M. Liehr, Ronald E. Olson, E. Salzborn

Physics Faculty Research & Creative Works

Absolute cross-sections have been measured and compared to CTMC-calculations for single and double-electron removal from H− in collisions with Ar^q+ ions (q ≤ 8) at E_c.m. = 50 keV. The single-electron removal cross-sections are found to scale with q^1.3, and for the H⁻ + Ar⁴⁺ system, this cross-section is found to have a weak energy dependence from 3 keV to 100 keV. A major implication of our measurements is that plasma neutralizers based on multiply charged ions for high-efficiency conversion of intense H⁻ beams into H⁰ gain little in expected reduced …

Long-Range Hopping In Substitutionally Disordered Solids, Paul Ernest Parris

Physics Faculty Research & Creative Works

A theoretical approach for studying charge-carrier and energy diffusion due to long-range hopping in substitutionally disordered solids is presented. Unlike some earlier theories, which invoke a pair approximation to treat back-transfer processes, the current theory makes use of the exact solution to an appropriate single-defect problemone in which long-range jumps into, out of, and between both the defect site and all other active sites in the lattice are explicitly included. From this exact solution a new long-range effective-medium theory is constructed to describe the configurationally averaged transport properties of the disordered system.

Automated Translation Of Digital Logic Equations Into Optimized Vhdl Code, John Evan Stark, George Winston Zobrist

Computer Science Technical Reports

It was desired to develop an algorithm for the automated translation of finite slate machines from state table form to optimized VHDL form. To do this, algorithms arc needed for reducing the state machine to simplest form, making state assignments, producing minimal logic equations to represent the state machine, and producing VHDL code which describes the intended circuit. Various such algorithms were examined and a prototype program written to perform this translation.

Spectroscopy Of The 6p3/2Np States Of Barium, J. Greg Story, E. G. Yap, William E. Cooke

Physics Faculty Research & Creative Works

The 6p_3/2np states of barium have been observed for n values between 14 and 21. The energies, linewidths, and transition strengths have been measured and characterized in terms of one- and two-electron interactions, using a single-configuration approximation.

Shake-Off Measurements Of Electron-Ion-Scattering Phase Shifts, J. Greg Story, William E. Cooke

Physics Faculty Research & Creative Works

Continuum electrons are produced in a specific l state with high-energy resolution using shake-off photoionization. This process is well characterized, so that the photoionization signal is an accurate measurement of the difference between the continuum electrons wave-function phase and that produced by a hydrogenic interaction. Measurements are reported showing the phase of a Ba⁺+e^- in a d wave, in cases where it is well behaved, and in cases where doubly excited resonances produce rapid phase variations.

Electron-Electron Interactions In Transfer And Excitation In F⁸⁺ →₂ Collisions, Michael Schulz, J. P. Giese, J. K. Swenson, Sheldon Datz, Peter F. Dittner, Herbert F. Krause, Harald Schone, Charles Randy Vane, Malika Benhenni, Stephen M. Shafroth

Physics Faculty Research & Creative Works

We have measured projectile Auger electrons emitted after collisions of H-like F with H₂. The cross sections for emission of KLL, KLM, KLN, and KLO Auger electrons show maxima as a function of the projectile energy. One maximum in the KLL emission cross section is due to resonant transfer and excitation. A second maximum in the cross section for KLL emission as well as the maxima in the emission cross section for the higher-n Auger electrons are attributed to a new transfer and excitation process. This involves excitation of a projectile electron by one target electron accompanied by …

On The Kelvin Electrostatic Generator, S. Desmet, F. Orban, Fernande Grandjean

Chemistry Faculty Research & Creative Works

The Kelvin generator is an amazing electrostatic device which poses many questions. The authors report the results of their investigations of this device under various controlled conditions with both nonpolar and polar liquids and a sodium chloride aqueous solution. They have found that the generator works well even if the two liquid streams originate from different electrically insulated reservoirs. In addition they propose a model in which the electric charge results from the separation of the hydrogen and hydroxyl ions as the water droplets form.

Condensation Coefficient Measurement For Water In The Umr Cloud Simulation Chamber, Donald E. Hagen, John L. Schmitt, Max B. Trueblood, John C. Carstens, Daniel R. White, Darryl J. Alofs

Physics Faculty Research & Creative Works

A systematic series of condensation coefficient measurements of water have been made using the University of Missouri-Rolla cooled-wall expansion chamber which simulates the thermodynamics of cloud. This coefficient is seen to decrease from a value near unity, at the outset of simulation, to a value in the neighborhood of 0.01 toward the end of a simulation. Final values of this coefficient are sufficiently low as to contribute significantly to the broadening of the drop-size distribution in cloud.

One-Dimensional Trapping Kinetics At Zero Temperature, Paul Ernest Parris

Physics Faculty Research & Creative Works

The asymptotic decay of the survival probability is calculated for a quantum particle moving at zero temperature on a one-dimensional tight-binding chain possessing randomly placed irreversible traps of strength γ. The survival probability exhibits a decay, P(t) ~ exp(-At^1/4), which is slower than that associated with a diffusing particle.

Seismic Signature Of A Swan Hills (Frasnian) Reef Reservoir, Snipe Lake, Alberta, Neil Lennart Anderson, Robert James Sidford Brown, Ronald C. Hinds, L. V. Hills

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Swan Hills formation (Frasnian stage) carbonate buildups of the Beaverhill Lake group are generally of low relief and considerable areal extent and are overlain by and encased within the relatively high-velocity shale of the Waterways formation, which thins but does not drape across the reefs. Consistent with this picture, prereef seismic events are not significantly pulled up beneath the reefs nor are postreef events draped across them. Indeed, the seismic images of these reefs are effectively masked by the high-amplitude reflections from the overlying top of the Beaverhill Lake group and underlying Gilwood member and cannot be distinguished from those …

Measured Spectra Of The Hygroscopic Fraction Of Atmospheric Aerosol Particles, Darryl J. Alofs, Donald E. Hagen, Max B. Trueblood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The relation between dry diameter (X₀) and critical supersaturation (S_c) for atmospheric submicron aerosol particles is investigated using a long term air sampling program at Rolla, Missouri. The particles are passed through an electrostatic aerosol size classifier, and then through an isothermal haze chamber. Results are reported in terms of an apparent volume fraction of soluble material, ε_v defined such that for particles composed only of ammonium sulfate and water insoluble compounds, ε_v is the actual volume fraction of soluble material. The probability distribution of ε_v is found to be approximately Gaussian in …

Elastic Angular Differential Cross Sections For Quasi-One-Electron Collision Systems At Intermediate Energies: (Na⁺, Li⁺)+H And (Mg⁺, Be⁺)+He, Jerry Peacher, E. Redd, Denver G. Seely, Timothy Gay, D. M. Blankenship, John T. Park

Physics Faculty Research & Creative Works

Measurements of elastic angular differential cross sections have been carried out for four quasi-one-electron collision systems at intermediate energies. Data are presented for Na⁺+H collisions at laboratory energies of 35.94, 51.75, 63.89, and 143.75 keV, for Li⁺+H collisions at energies of 19.44 and 43.75 keV, for Mg⁺+He collisions at energies of 30, 66.7, and 150 keV, and for Be⁺+He collisions at an energy of 56.25 keV. The highest energy in each case corresponds to a projectile velocity of (1/2 a.u. Born and Eikonal calculations, in which we model the projectile ion as …

An Improved Exact Graph Coloring Algorithm, Thomas J. Sager, Shi-Jen Lin

Computer Science Technical Reports

We present two algorithms for exact graph coloring of the vertex sequential with dynamic reordering of vertices variety. The first, W-DEG, is a straight-forward improvement on Korman’s original algorithm. The second, SWAP2, is a not so straight forward improvement on Korman’s algorithm and appears to offer the best performance of known exact graph coloring algorithms.

A Color-Exchange Algorithm For Exact Graph Coloring, Thomas J. Sager, Shi-Jen Lin

Computer Science Technical Reports

DEXCH, a color-exchange exact graph coloring algorithm is presented. On many classes of graphs, DEXCH can, in the mean, find the chromatic number of a graph considerably faster than the DSATUR algorithm. The improvement over DSATUR stems from the ability to reorganize the subset of colored vertices and to detect in certain instances the existence of a complete subgraph of cardinality equal to the number of colors used in the best coloring found so far. The mean improvement over DSATUR is greatest on high edge-density graphs attaining the value of 42% on random graphs of edge-density 0.7 on 64 vertices.

A Pruning Procedure For Exact Graph Coloring, Thomas J. Sager, Shi-Jen Lin

Computer Science Technical Reports

The graph coloring problem can be stated: “Given an undirected graph, using a minimal number of colors, assign each vertex a color so that if two vertices are connected by an edge then they are not assigned the same color.” Graph coloring can be used to solve scheduling problems with constraints of the form: events e and e' can not be scheduled together. Graph coloring is an NP-Complete problem. Generally large problems are solved heuristically, although some of the better heuristic algorithms use an exact graph coloring algorithm to finish coloring a graph after first reducing it heuristically …

Robustness & Precision Of Parametric & Distribution-Free Tolerance Limits For Two Lifetime Distributions, Wei Kei Shiue, Lee J. Bain

Mathematics and Statistics Faculty Research & Creative Works

Exact parametric tolerance limits or confidence limits on reliability are not available for the gamma distribution, and it is, difficult to determine approximate methods which are accurate for all parameter values. The precision lost by using the distribution-free tolerance-limit method based on the first order statistic, compared to using an approximate gamma tolerance limit method is studied. The robustness of the approximate gamma tolerance limit when the true model is Weibull and the robustness of a Weibull tolerance limit when the true model is gamma are also studied. The efficiency of the distribution-free method ranges from about 0.60 to 0.90 …

Sharp Lower Bounds For A Generalized Jensen Inequality, A. K. Rigler, S. Y. Trimble, R. S. Varga

Mathematics and Statistics Faculty Research & Creative Works

No abstract provided.

Periodic Points For Homeomorphisms Of Hereditarily Decomposable Chainable Continua, W. T. Ingram

Mathematics and Statistics Faculty Research & Creative Works

In this paper it is shown that homeomorphisms of hereditarily decomposable chainable continua cannot have periodic points whose periods are not powers of two. Examples show that for each power of two there is a hereditarily decomposable chainable continuum and a homeomorphism of it which has a periodic point of period that power of two. © 1989 American Mathematical Society.

Classical Two-Center Effects In Ejected-Electron Spectra From P+, P-, And He2++He Collisions At Intermediate Energies, C. O. Reinhold, Ronald E. Olson

Physics Faculty Research & Creative Works

Doubly and singly differential cross sections for electron emission have been calculated by means of the classical trajectory Monte Carlo method for the p⁺, p-, and He²⁺+He systems at impact energies of 50 and 100 keV/amu. The calculations for the p⁺ and He²⁺+He systems exhibit the capture to the continuum peak and agree in both shape and magnitude with experimental data. Analysis of the classical trajectories has helped to understand the dynamical formation of this peak. The dependence of the cross sections on the projectile charge (-1, +1, and +2) is analyzed and …

Exciton Diffusion At Finite Frequency: Luminescence Observables For Anisotropic Percolating Solids, Paul Ernest Parris

Physics Faculty Research & Creative Works

A study is made of the luminescence intensities associated with exciton diffusion and trapping on a three-dimensional anisotropic percolating lattice. The calculation is based upon a relationship that exists between the frequency dependent diffusion tensor at frequencies comparable to the inverse excitation lifetime, and luminescence observables such as the host and trap luminescence intensities for conditions of constant illumination. The present approach allows the study of crossover behavior in percolative systems that are of intermediate transport dimensionality 2 < d_t < 3. Our results suggest that curvature seen in luminescence observables near the transition need not always be a direct reflection of the critical indices associated with classical isotropic percolation. We have identified three possible sources of deviation from the classical behavior: (1) the radiative time scale of the luminescence measurements, (2) the functional dependence of the luminescence yields on the diffusion tensor, and (3) the demands of dimensional crossover in the critical region arising from the anisotropy of the medium.