Physical Sciences and Mathematics Commons^™

Final State Distributions For Electron Capture From Orientated Rydberg Atoms, Jee-Ching Wang, Ronald E. Olson

Chemical and Biochemical Engineering Faculty Research & Creative Works

Final state nim distributions are studied for electron capture from orientated circular Rydberg atoms. Strong orientation effects are found for all quantum numbers at collision speeds comparable to the electron orbital speed. Predominant population of large m states is observed when the plane of the circular orbit is nearly perpendicular to the incident direction of the projectile. The Ini distributions show structures due to quasi-Thomas scattering even at low relative collision velocities. © 1993 IOP Publishing Ltd.

A Simulated Annealing/Tabu Search Algorithm For The Vehicle Routing Problem, Jeffrey Dale White, Billy E. Gillett

Computer Science Technical Reports

The Vehicle Routing Problem is an NP-complete problem that has been studied extensively since it was introduced in 1958 by G. B. Dantzig and J. H. Ramser. This thesis creates three algorithms that endeavor to find an optimal solution for each problem tested. Two of the algorithms (Simulated Annealing and Tabu Search) have been used previously to solve this problem. These two solution methods are revisited to discover whether a new approach to creating routes will produce the best-known optimal values every time. New routes are created by forming route neighborhoods and then selecting cities from these neighborhoods for insertion. …

Process Driven Software Engineering Environments, John Hayes Lampkin, T. Lo, Daniel C. St. Clair

Computer Science Technical Reports

Software development organizations have begun using Software Engineering Environments (SEEs) with the goal of enhancing the productivity of software developers and improving the quality of software products. The encompassing nature of a SEE means that it is typically very tightly coupled with the way an organization does business. To be most effective, the components of a SEE must be well integrated and the SEE itself must be integrated with the organization.

The challenge of tool integration increases considerably when the components of the environment come from different vendors and support varying degrees of “openness”. The challenge of integration with the …

Subsumption In Modal Logic, Dirk Heydtmann, Ralph W. Wilkerson

Computer Science Technical Reports

Subsumption has long been known as a technique to detect redundant clauses in the search space of automated deduction systems for classical first order logic. In recent years several automated deduction methods for non-classical modal logics have been developed. This thesis explores, how subsumption can be made to work in the context of these modal logic deduction methods.

Many modern modal logic deduction methods follow an indirect approach. They translate the modal sentences into some other target language, and then determine whether there exists a proof in that language, rather than doing deduction in the modal language itself. Consequently, subsumption …

The Difficulty Of Approximating The Chromatic Number For Random Composite Graphs, Jeffrey Wayne Jenness, Billy E. Gillett

Computer Science Technical Reports

Combinatorial Optimization is an important class of techniques for solving Combinatorial Problems. Many practical problems are Combinatorial Problems, such as the Traveling Salesman Problem (TSP) and Composite Graph Coloring Problem (CGCP). Unfortunately, both of these problems are NP-complete and it is not known if efficient algorithms exist to solve these problems. Even approximation with guaranteed results can be just as difficult. Recently, many generalized search techniques have been developed to improve upon the solutions found by the heuristic algorithms.

This paper presents results for CGCP. In particular, exact and heuristic algorithms are presented and analyzed. This study is made, to …

A Syntax-Directed Editor For Borland’S Turbo Pascal, John Gatewood Ham, Thomas J. Sager

Computer Science Technical Reports

This study details the design and implementation of the LSD program, a syntax-directed editor for use in editing the source code for Borland’s Turbo Pascal. LSD is a dual-mode editor which allows both traditional text editing and also grammar-based editing. LSD promotes better programming for novice users by allowing the user to edit the program with a graphical representation of a parse tree. A list of syntactically correct choices is displayed at each point where a choice must be made in the structure of the program. Since only these choices are available, no syntax errors are possible. For more advanced …

Fault-Tolerant Ring Embeddings In Hypercubes -- A Reconfigurable Approach, Jun-Lin Liu, Bruce M. Mcmillin

Computer Science Technical Reports

We investigate the problem of designing reconfigurable embedding schemes for a fixed hypercube (without redundant processors and links). The fundamental idea for these schemes is to embed a basic network on the hypercube without fully utilizing the nodes on the hypercube. The remaining nodes can be used as spares to reconfigure the embeddings in case of faults. The result of this research shows that by carefully embedding the application graphs, the topological properties of the embedding can be preserved under fault conditions, and reconfiguration can be carried out efficiently.

In this dissertation, we choose the ring as the basic network …

Neutron-Diffraction And Mössbauer-Effect Studies Of Pr₂(Fe₁₋ₓmnₓ)₁₄B, Oran Allan Pringle, Jie Fu, Gary J. Long, William Joseph James, Decai Xie, William B. Yelon, Fernande Grandjean

Physics Faculty Research & Creative Works

A neutron-diffraction investigation of a series of Pr₂(Fe _1-xMn_x)₁₄B samples, with x values of 0.00, 0.11, 0.22, 0.30, and 0.35, reveals a preference for the manganese to occupy the 8j₂ transition-metal site,the transition-metal site with the largest Wigner-Seitz cell volume. Similar site occupancies have been reported previously for Er₂(Fe_1-xMn_x) ₁₄B and Y₂(Fe_1-xMn_x) ₁₄B. An analysis of the 295-K Mössbauer spectrum of Pr₂(Fe_0.89Mn_0.11)₁₄B indicates that the internal hyperfine fields on the …

High-Voltage Variable Resistor For Ion Energy Spectroscopy, Timothy James Gay, V. D. Irby, S. P. Yallaly

Physics Faculty Research & Creative Works

A high-voltage variable resistor was designed, built, and implemented to modify an ion-energy spectrometer for the study of ion-atom collisions in which the projectiles change charge. The resistor is remotely switchable from 0 to 2050 MΩ and has a voltage rating of 200 kV. The design criteria and the electrical and mechanical details of the apparatus are discussed. The design and construction of an ancillary device, comprising two precision resistive-divider voltmeters, are also discussed.

Ionic Charge Dependence Of The Zero Degree Binary Encounter Peak For Partially Stripped Heavy Ions, W. Wolff, H. E. Wolff, J. L. Shinpaugh, Jee-Ching Wang, Ronald E. Olson, D. Fainstein, S. Lencinas, U. Bechthold, R. Herrmann, H. Schmidt-Bocking

Chemical and Biochemical Engineering Faculty Research & Creative Works

We report on the measurements of double differential cross sections, at zero degree, for the production of secondary electrons from the collision of 0, 6 MeV amu^-1 Cu⁵⁺, I⁷⁺, Au¹¹⁺, U¹³⁺, Cu¹⁹⁺, t²³⁺ and Au²⁹⁺ projectiles with H₂ and He. The shapes and positions of the observed binary encounter electron peaks are compared with continuum distorted wave-eikonal initial state (CDW-EIS), impulse approximation and classical trajectory Monte Carlo calculations, as well as with predictions from an adiabatic resonant tunnelling model recently proposed by Fainstein and co-workers. The …

Asynchronous Parallel Schemes: A Survey, Eric Jui-Lin Lu, Michael Gene Hilgers, Bruce M. Mcmillin

Computer Science Technical Reports

It is well known that synchronization and communication delays are the major sources of performance degradation of synchronous parallel algorithms. It has been shown that asynchronous implementations have the potential to reduce the overhead to minimum. This paper surveys the existing asynchronous schemes and the sufficient conditions for the convergence of the surveyed schemes. Some comparisons among these schemes are also presented.

Large-Cell Renormalization-Group Approach To Long-Range Hopping On Energetically Disordered Lattices, B. D. Bookout, Paul Ernest Parris

Physics Faculty Research & Creative Works

We describe an approach for computing the conductivity associated with long-range hopping on energetically disordered lattices. Using a numerically exact supercell procedure we compute the distribution ρL(γ) of block conductances γL associated with conducting cubes of edge length L that are randomly chosen from the disordered system of interest. This distribution of block conductances is then used in a self-consistent numerical calculation to obtain the renormalized bulk conductivity. The approach displays a surprisingly fast approach to the infinite-system limit, allowing finite-size effects to be minimized. In this paper we use this approach to study transport in a series of binary …

An Integrated Surface And Borehole Seismic Case Study: Fort St. John Graben Area, Alberta, Canada, Ronald C. Hinds, Richard Kuzmiski, Neil Lennart Anderson, Barry R. Richards

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The deltaic sandstones of the basal Kiskatinaw Formation (Stoddard Group, upper Mississippian) were preferentially deposited within structural lows in a regime characterized by faulting and structural subsidence. In the Fort St. John Graben area, northwest Alberta, Canada, these sandstone facies can form reservoirs where they are laterally sealed against the flanks of upthrown fault blocks. Exploration for basal Kiskatinaw reservoirs generally entails the acquisition and interpretation of surface seismic data prior to drilling. These data are used to map the grabens in which these sandstones were deposited, and the horst blocks which act as lateral seals. Subsequent to drilling, vertical …

Simulation Of Bulk Silicon Crystals And Si(111) Surfaces With Application To A Study Of Fluorine Coverage Of The Surfaces, Chen K. Lutrus, T. Oshiro, Donald E. Hagen, Sung-Ho Suck Salk

Physics Faculty Research & Creative Works

Computational efficiency for the simulation of bulk crystals and surfaces is highly desirable. In an effort to study semiconductor crystals, we present a self-consistent treatment for the simulation of silicon crystals and surfaces based on the combination of a siligen model and a semiempirical Hamiltonian method. An artificial atom called siligen is introduced for the application of the semiempirical method to finite-size silicon clusters. The calculated average bond energies for the saturated silicon clusters are between 2.045 and 2.568 eV, compared to the measured value of 2.31 eV. A simulated bulk silicon surface using siligens is introduced in order to …

Neutron-Diffraction And Mössbauer Effect Study Of The Preferential Silicon Site Occupation And Magnetic Structure Of Nd₂Fe₁₄₋ₓsiₓb, Gaya Kanishka Marasinghe, Oran Allan Pringle, Gary J. Long, William Joseph James, Dianne J. Xiao, J. L. Li, William B. Yelon, Fernande Grandjean

Physics Faculty Research & Creative Works

A neutron-diffraction study of Nd₂Fe_14-xSi_xB has shown that silicon preferentially occupies the 4c site in the transition-metal sublattice in Nd₂Fe₁₄B. Silicon also exhibits a moderate preference for the 8j₁ site, is almost excluded from the 16k₂ site, and avoids the 16k₁, 8j₂, and 4e sites. The silicon site occupancy is correlated with a preference for a silicon atom to have rare-earth atoms in its coordination environment. The Mössbauer spectra of Nd₂Fe_14-xSi_xB have been fit with a model which …

An Integrated Surface Seismic/Seismic Profile Case Study: Simonette Area, Alberta, Ronald C. Hinds, Neil Lennart Anderson, Richard Kuzmiski

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

On the basis of conventional surface seismic data, the 13-15-63-25W5M exploratory well was drilled into a low-relief Leduc Formation reef (Devonian Wood-bend Group) in the Simonette area, west-central Alberta, Canada. The well was expected to intersect the crest of the reef and encounter about 50-60 m of pay; unfortunately it was drilled into a flank position and abandoned. The decision to abandon the well, as opposed to whipstocking in the direction of the reef crest, was made after the acquisition and interpretive processing of both near-and far-offset (252 and 524 m, respectively) vertical seismic profile (VSP) data, and after the …

Spatially Resolved Transitions To Autoionizing States, J. Greg Story, D. I. Duncan, Thomas F. Gallagher

Physics Faculty Research & Creative Works

We have observed transitions to autoionizing states in Mg using two short optical pulses. Mg atoms are initially prepared in a high lying Rydberg wave packet with the first ps laser. A second ps laser is then used to excite the inner electron, producing an autoionizing state. The dependence of the transition probability on the delay between the two lasers shows that when the second laser is tuned away from the ionic resonance, the inner electron can make a transition only when the Rydberg wave packet is near the core.

Using Temporal Subsumption For Developing Efficient Error-Detecting Distributed Algorithms, Martina Schollmeyer, Bruce M. Mcmillin

Computer Science Technical Reports

Distributed algorithms can use executable assertions derived from program verification to detect errors at run-time. However, a complete verification proof outline contains a large number of assertions, and embedding all of them into the program to be checked at run-time would make error-detection very inefficient.

The technique of temporal subsumption examines the dependencies between the individual assertions along program execution paths. In contrast to classical subsumption, where all logical expressions to be examined are true simultaneously, an assertion need only be true when the corresponding statement in the distributed program has been executed. Thus, temporal subsumption based on the set …

A Run-Time Decision Procedure For Responsive Computing Systems, Grace Tsai, Matt Insall, Bruce M. Mcmillin

Computer Science Technical Reports

A responsive computing system is a hybrid of real-time, distributed and fault-tolerant systems. In such a system, severe consequences will occur if the logical and physical specifications of the system are not met. In this paper, we present a logic, Interval Temporal Logic (ITL), to specify responsive systems and give decision procedures to verify properties of the system at run-time as follows. First, we collect, during execution, events occurring in the system to represent a distributed computation. Next, we specify properties of the system using ITL formulas. Finally, we apply the decision procedures to determine satisfaction of the formulas. Thus, …

Differential Cross Sections For Single And Double Ionization Of Helium By Protons And Antiprotons, L. Meng, Ronald E. Olson, R. Dömer, J. Ullrich, H. Schmidt-Bocking

Physics Faculty Research & Creative Works

Theoretical and experimental cross sections are presented for single and double ionization of He differential in the projectile scattering angle and the transverse energy of the outgoing recoil ion. A dynamical four-body classical trajectory Monte Carlo method that includes radial electron correlation is utilized to calculate total and differential cross sections for 300 and 500 keV protons and antiprotons in impact collisions with He. The azimuthal emission characteristics of electrons, recoil ion and projectile relative to each other are analyzed to provide detailed information on the dynamical differences between single and double ionization and between proton and antiproton impact. © …

Energy-Projected Effective-Medium Theory Of Long-Range Hopping On Energetically Disordered Lattices, Paul Ernest Parris, B. D. Bookout

Physics Faculty Research & Creative Works

We introduce energy-projected equations of motion to treat the diffusive transport of charge carriers that undergo long-range (i.e., greater than nearest-neighbor) hopping among the sites of an energetically disordered lattice. This approach leads naturally to an energy-projected effective-medium theory for treating such systems. Exact expressions for the diffusion constant associated with the energy-projected effective medium theory are obtained. Using the formalism in conjunction with what is normally a rather poor approximation, i.e., the virtual-crystal approximation, we are able to obtain the exact diffusion constant for the long-range symmetric-random-well problem. Effective-medium calculations and numerical simulations are presented for nearest-neighbor and long-range …

Separation And Characterization Of Components Of Catalytic Cracker Feed Using Centrifugal Partition Chromatography, Randy A. Menges, Daniel W. Armstrong, Larry A. Spino

Chemistry Faculty Research & Creative Works

Centrifugal partition chromatography (CPC) was used to fractionate a catalytic-cracking feedstock (i.e., catalytic cracker feed) into 16 separate fractions in the descending mode and 5 fractions in the inverse or ascending mode. Each fraction was analyzed by UV, fluorescence, and synchronous luminescence (SL) spectroscopy as well as by gas chromatography/mass spectrometry (GC/MS). It appeared that CPC can be used to fractionate larger samples of this type and with a greater degree of selectivity than previously reported preparative HPLC approaches. The SL spectra tended to be much more useful and information rich for these complex mixtures as compared to UV or …

Comparative Study Of Louville And Symplectic Integrators, Daniel I. Okunbor

Computer Science Technical Reports

In this paper, we construct an integrator that conserves volume in phase space. We compare the results obtained using this method and a symplectic integrator. The results of our experiments do not reveal any superiority of the symplectic over strictly volume-preserving integrators. We also investigate the effect of numerically conserving energy in a numerical process by rescaling velocities to keep energy constant at every step. Our results for Henon-Heiles problem show that keeping energy constant in this way destroys ergodicity and forces the solution onto a periodic orbit.

Quantal And Classical Correspondence Of Double Scattering, Jianyi Wang, Ronald E. Olson, Karoly Tokési

Physics Faculty Research & Creative Works

Electron emission from atom-atom collisions is analyzed within the framework, of both quantal and classical dynamics. We examine the effect of explicit electron-electron (e-e) interactions on the ejected electron spectra in hard collisions involving simultaneous excitation and ionization in the collision of two structured atoms. A double scattering sequence represented by a second order Bom approximation has been shown to give a dominant contribution over the single scattering to projectile ionization. A classical simulation confirms the double scattering process is analogous to the Thomas two-step capture mechanism. We find good agreement between quantal and classical calculations, showing the convergence of …

Constructing An Interval Temporal Logic For Real-Time Systems, Grace Tsai, Matt Insall, Bruce M. Mcmillin

Computer Science Technical Reports

A real-time system is one that involves control of one or more physical devices with essential timing requirements. Examples of these systems are command and control systems, process control systems, flight control systems, and the space shuttle avionics systems. The characteristics of these systems are that severe consequences will occur if the logical and physical timing specifications of the systems are not met.

Formal specification and verification are among the techniques to achieve reliable software for real-time systems, in which testing may be impossible or too dangerous to perform. This paper presents a modal logic, Interval Temporal , built upon …

Transition From Quantum To Quasi-Classical Behaviour Of The Binary Encounter Peak In Collisions Of 0.6 To 3.6 Mev Amu“¹ I23+ And Xe21+ With He And Ar, J. L. Shinpaughfg, W. Wolff, H. E. Wolff, U. Ramm, O. Jagutzki, H. Schmidt-Böcking, J. Wangt, Ronald E. Olson

Physics Faculty Research & Creative Works

Double differentia] cross sections are reported for the production of binary encounter electrons in collisions of 0.6 MeV amu^-1 I²³⁺ and 1.4, 2.4, and 3.6 MeV amu^-1 Xe²¹⁺ projectiles incident on He and Ar targets. Electron energy spectra were measured between 0: and 45: in the case of the two lower projectile energies, and between 17.5° and 60- for the two higher projectile energies. The data are compared with quantum mechanical impulse approximation and classical trajectory Monte Carlo calculations. While the quantum model calculation predicts a rapid disappearance of diffraction effects in the binary encounter peak …

An Overview Of Some Of The Large Scale Mechanisms Of Salt Dissolution In Western Canada, Neil Lennart Anderson, Ralph W. Knapp

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Well log and seismic data indicate that the bedded rock salts of the Devonian Prairie Formation were widely distributed and uniformly deposited in the Lloydminster area, Western Canada; however, as a result of extensive leaching, the distribution of these salts is not now what it once was. The Lloydminster area is now bisected by the north-south trending main dissolutional edge of the Prairie salt. Thick salt (up to 150 m) is preserved to the west of this edge; to the east the salt is mostly absent. The paper presents an overview of the envisioned principal mechanisms of salt dissolution. The …

Dependence Of Binary Encounter Electron Production On The Charge State Of The Recoil Ion, Jee-Ching Wang, Ronald E. Olson, H. Wolf, J. Shinpaugh, W. Wolff, H. Schmidt Böcking

Chemical and Biochemical Engineering Faculty Research & Creative Works

We study the dependence of the production of binary encounter electrons on the charge state of recoil ions for 2.4 MeV u^-l Xe²¹⁺ on He and Ar. Doubly differential cross sections of electron emission are calculated with the ncrMC method. We find that the contributions to the binary electron cross section from various recoil ion charge states reach a maximum near Ar⁵⁺ for the Ar target. In the case of the He target; double ionization dominates over single ionization for alt ejected electron energies above 100 eV. However, an unexpected local drop of double ionization in the …

Implicit Methods On Parallel Processors, Larry Reeves

Computer Science Technical Reports

Since most partial differential equations (PDEs) do not have exact solutions, they are usually solved by some type of numerical method. Since a numerical method is commonly built from finite difference approximations derived from Taylor series expansions, such a development is derived. Stability and convergence of these methods is defined and the rate of convergence is defined and shown for a few simple methods. Of particular importance is the difference between implicit and explicit methods. Finally, the current applications and adaptations of implicit methods on parallel processors are examined and their strengths and weaknesses discussed.

Formal Model And Specification Of Deadlock, Pei-Yu Li, Bruce M. Mcmillin

Computer Science Technical Reports

In this paper, we present a formal model of deadlock in a distributed system and develop the deadlock specification in terms of time-dependent predicates. Primitive activities of processes in the distributed system are specified by the predicates so that system behaviors can be described by logic operations. With the formal model, we have an insight into the definition of deadlock in local views. A rigorous proof to show the equivalence of local-time and global-time deadlock specifications is presented. The local-time deadlock specification, which defines the timing of dependence between deadlocked processes, will be useful in the correctness verification of distributed …