Physical Sciences and Mathematics Commons^™

A Mössbauer Effect Study Of Y₂Fe₁₄B And Its Aluminum Solid Solutions, Dwayne E. Tharp, Gary J. Long, Oran Allan Pringle, Gaya Kanishka Marasinghe, William Joseph James, Fernande Grandjean

Chemistry Faculty Research & Creative Works

The Mössbauer spectra of Y₂Fe₁₄B have been measured from 85 to 296 K. Analysis of the spectra indicates that the near-neighbor rare-earth atoms directly influence the orientation of the principal axis of the electric field gradient. The hyperfine parameters are very similar to those of Nd₂Fe₁₄B, but the internal fields are somewhat smaller at room temperature in the yttrium compound. The Mösssbauer spectra of Y₂(Fe_1-xAl_x) ₁₄B, where x equals 0.00, 0.02, 0.04, 0.06, and 0.08, have been measured at 85 K. The average internal hyperfine …

Resonant Transfer And Excitation In Li-Like F Colliding With H₂, Michael Schulz, Reinhold S. Schuch, Sheldon Datz, Edson L B Justiniano, Philip D. Miller, Harald Schone

Physics Faculty Research & Creative Works

We have measured coincidences between x rays and projectiles that have captured one electron in F⁶⁺ + H₂ collisions at projectile energies between 15 and 33 MeV. The cross sections for capture and simultaneous x-ray emission as a function of projectile energy show clear structures. Indications of an unexpectedly high population of high-n states predominantly formed by resonant transfer and excitation (RTE) were found. Above the Kln (n>1) RTE resonance energies another maximum was observed.

Excitation Of The Lowest Autoionizing Levels In Lithiumlike Ions By Electron Impact, Rajesh C. Srivastava, Don H. Madison

Physics Faculty Research & Creative Works

We present theoretical, differential, and total cross sections for electron impact excitation of the lowest autoionizing levels of various lithiumlike ions (viz., Be⁺, B²⁺, C³⁺, O⁵⁺, and Ne⁷⁺). For these ions, the autoionizing level of interest results from excitation of an inner-shell electron. A distorted-wave Born approximation (with exchange) is used for the calculation. The present results are compared with previous theoretical calculations and it is concluded that the Coulomb-Born approach is unreliable, particularly near threshold.

A Neutron Diffraction And Mössbauer Spectral Study Of The Structure And Magnetic Properties Of The Y₂Fe₁₄₋ₓsiₓb Solid Solutions, Gaya Kanishka Marasinghe, Oran Allan Pringle, Gary J. Long, William B. Yelon, Fernande Grandjean

Physics Faculty Research & Creative Works

A neutron diffraction and Mössbauer spectral study of Y₂Fe_14-xSi_xB shows that silicon preferentially occupies the 4c, and to a lesser extent, the 8j₁ sites in Y₂Fe_14-xSi_xB. The trend in the site occupancy is the same as in Nd₂Fe_14-xSi_xB. The Curie temperature of Y₂Fe_14-xSi_xB increases with increasing silicon content. Neutron diffraction data show that the increase in Curie temperature is accompanied by a contraction of the unit cell. Wigner-Seitz cell calculations, using the Y₂Fe …

Concerning Periodic Points In Mappings Of Continua, W. (William) T. (Thomas) Ingram

Mathematics and Statistics Faculty Research & Creative Works

In this paper we present some conditions which are sufficient for a mapping to have periodic points. © 1988 American Mathematical Society.

Temperature And Supersaturation Dependent Nucleation Rates Of Water By Molecular Cluster Model Calculations, Sung-Ho Suck Salk, Chen K. Lutrus, Donald E. Hagen

Physics Faculty Research & Creative Works

Using a microphysical approach to nucleation, we present an extensive study of water nucleation rates for wide ranges of both temperature and supersaturation ratio. Based on the fundamental molecular properties of clusters instead of bulk properties, the microphysical approach is demonstrated to predict good agreement with measured nucleation rates over this broad range of conditions. Predicted critical sizes for nucleation are found to be relatively small, and are in the molecular cluster size regime rather than in a size regime that should be characterized by bulk values. Estimated sticking coefficient values cover the range of ~0.9 to ~0.2 for the …

Enantiomeric Resolution And Chiral Recognition Of Racemic Nicotine And Nicotine Analogues By Β-Cyclodextrin Complexation: Structure-Enantiomeric Resolution Relationships In Host-Guest Interactions, Jeffrey I. Seeman, Henry V. Secor, Daniel W. Armstrong, Karen D. Timmons, Timothy J. Ward

Chemistry Faculty Research & Creative Works

High-performance liquid chromatography using β-cyclodextrin bonded phases was examined for the enantiomeric separation of racemic nicotine and 19 racemic nicotine analogues. Ten pairs of enantiomers were separated by this technique. This represents the first reported facile and direct separation of these racemates. Effects of pH, mobile phase composition, and structural features of the substrates (i.e., position and size of substituents, presence of pyrrolidine ring or hydrogen bonding functionalities, basicity) on the enantioselectivity are examined. Various structural aspects of the compounds were related to retention to the cyclodextrln-modlfied support and to the enantiomeric separations observed. Implications of this work to host-guest …

Kinetics And Mechanisms Of The Aminolysis Of N-Hydroxysuccinimide Esters In Aqueous Buffers, Gary W. Cline, Samir B. Hanna

Chemistry Faculty Research & Creative Works

Rate constants for the aminolysis of the N-hydroxysuccinimide (NHS) ester of ρ-methoxybenzoic acid, in aqueous buffer systems (20% dioxane), have been determined under pseudo-first-order conditions. For the amines studied (pK_a = 7.60-11.1), the data fit the rate expression k_obsd - K_OH-⨯ [OH-] = k₁[amine]_free. This rate equation is in contrast to the two-term rate equation (k_obsd = k₁[amine] + k₂[amine]²) obtained for this reaction in anhydrous dioxane (Cline, G. W.; Hanna, S. B. J. Am. Chem. Soc. 1987,109, 3087) and is suggestive of a disproportionate …

Use Of Secondary Equilibria For The Separation Of Small Solutes By Field-Flow Fractionation, Alain Berthod, Daniel W. Armstrong, J. Calvin Giddings, Marcus N. Myers

Chemistry Faculty Research & Creative Works

The dynamic range and selectivity of field-flow fractionation (FFF) can be Increased by using secondary chemical equilibria (SCE). SCE are established by adding a macromolecular additive or aggregate, which strongly Interacts with the field, to the carrier solution. In this study an oil-ln-water (O/W) microemulsion was used as the carrier solution in a sedimentation FFF apparatus. The microemulsion droplets (referred to as the "support") interact with the field and are retained relative to the bulk water. Small solutes that partition or bind to the microemulsion droplets are also retained relative to solutes that do not Interact with the support. In …

Computer Science—A Mathematical Science And Accreditation, Frank Garnett Walters

Mathematics and Statistics Faculty Research & Creative Works

No abstract provided.

Transport Properties Of Ground State Oxygen Atoms, Paul M. Holland, Louis Biolsi Jr.

Chemistry Faculty Research & Creative Works

The transport properties of dilute monatomic gases depend on the two body interactions between like atoms. When two ground state oxygen atoms interact, they can follow any of 18 potential energy curves corresponding to O₂, all of which contribute to the transport properties of the ground state atoms. Transport collision integrals have been calculated for those interactions with an attractive minimum in the potential by accurately representingab initio quantum mechanical potential energy curves with the Hulburt-Hirschfelder potential. Repulsive ab initio potential energy curves have been accurately represented either with the exponential repulsive potential or with an exponential …

Composite Graph Coloring Algorithms And Applications, Stephen Hong Seng Yek, Billy E. Gillett

Computer Science Technical Reports

A vertex-composite graph is a graph that can have unequal chromaticities on its vertices. Vertex-composite graph coloring or composite graph coloring involves coloring each vertex of a composite graph with consecutive colors according to the vertex's chromaticity with no two vertices adjacent to one another having the same color(s).

New heuristic algorithms including the use of the saturation degree method have been developed in this research. All eleven heuristic algorithms including Clementson and Elphick algorithms were then tested using random composite graphs with five different chromaticity distributions. The best algorithm which uses the least average colors from the experiment is …

Theoretical Study Of Structure And Reactions Of Metalated Oximes And Oxime Ethers, Rainer Glaser, Andrew J. Streitwieser

Chemistry Faculty Research & Creative Works

The potential energy surfaces of acetaldoxime carbanion and its ion pairs formed with lithium and sodium cations ions have been explored with ab initio methods to model and study the regiochemistry of metalated oxime ethers. Planar structures of the carbanions produced by deprotonating acetaldoxime are minima on the potential energy surface. The syn-isomer is 2.6 Kcal/mole more stable than the anti. This difference is not a manifestation of cyclic conjugation but more likely is a result of electrostatic effects. Two chiral and almost isoenergetic minima have been located for the ion pairs formed by either of the isomeric carbanions with …

Complete Sets Of Reductions Modulo A Class Of Equational Theories Which Generate Infinite Congruence Classes, Timothy B. Baird, Ralph W. Wilkerson

Computer Science Technical Reports

In this paper we present a generalization of the Knuth-Bendix procedure for generating a complete set of reductions modulo an equational theory. Previous such completion procedures have been restricted to equational theories which generate finite congruence classes. The distinguishing feature of this work is that we are able to generate complete sets of reductions for some equational theories which generate infinite congruence classes. In particular, we are able to handle the class of equational theories which contain the associative, commutative, and identity laws for one or more operators.

We first generalize the notion of rewriting modulo an equational theory to …

The Role Of Term Symmetry In E-Unification And E-Completion, Blayne E. Mayfield, Ralph W. Wilkerson

Computer Science Technical Reports

A major portion of the work and time involved in completing an incomplete set of reductions using an E-completion procedure such as the one described by Knuth and Bendix [070] or its extension to associative-commutative equational theories as described by Peterson and Stickel [PS81] is spent calculating critical pairs and subsequently testing them for coherence. A pruning technique which removes from consideration those critical pairs that represent redundant or superfluous information, either before, during, or after their calculation, can therefore make a marked difference in the run time and efficiency of an E-completion procedure to which it is applied.

The …

High-Pressure Neutron-Scattering Studies Of Graphite And Stage-Two Graphite-Sbcl₅, B. Alzyam, Clive H. Perry, C. Zahopoulos, Oran Allan Pringle, Robert M. Nicklow

Physics Faculty Research & Creative Works

The longitudinal-acoustic (LA) phonons propagating along the c axis in highly oriented pyrolytic graphite (HOPG) were investigated as a function of pressure up to 20 kbar using inelastic-neutron-scattering techniques. The phonon frequencies varied as (P,q)=A(P)sin[c(P)q/2], where A(P) and c(P) indicate the pressure dependences of the zone-center LO frequency of B_1g1 symmetry and of the c-axis lattice spacing, respectively. From the measurements, the mode Grüneisen parameter for the LA branch was estimated to be 1.5 x 10^-2 kbar^-1 (independent of q); the elastic constant C₃₃ for HOPG was found to be 3.40 x 10¹¹ dyn/cm …

Gelled Emulsions With A High Water Content, C. Solans, J. G. Dominguez, J. L. Parra, J. Heuser, Stig Friberg

Chemistry Faculty Research & Creative Works

The structure of a gel containing 99% water, 0.5% of a nonionic surfactant and 0.5% of a hydrocarbon was investigated by analysis of its equilibrium phases and their state of dispersion by liquid helium freeze fracture electron microscopy. The gel consisted of aqueous droplets of micron size separated by a thin membrane of a lamellar liquid crystal and a W/O microemulsion with droplets varying between 200 and 1000 Å in diameter. © 1988 Steinkopff.

Automated Circuit Diagnosis Using First Order Logic Tools, Barbara Smith, Ralph W. Wilkerson, Gerald E. Peterson, Mcdonnell Douglas

Computer Science Faculty Research & Creative Works

While Numerous Diagnostic Expert Systems Have Been Successfully Developed in Recent Years, They Are Almost Uniformly based on Heuristic Reasoning Techniques (I.e., Shallow Knowledge) in the Form of Rules. This Paper Reports on an Automated Circuit Diagnostic Tool based on Reiter's Theory of Diagnosis. in Particular, this is a Theory of Diagnosis based on Deep Knowledge (I.e., Knowledge based on Certain Design Information) and using First Order Logic as the Representation Language. the Inference Mechanism Which is Incorporated as Part of the Diagnostic Tool is a Refutation based Theorem Prover using Rewriting Systems for Boolean Algebra Developed by Hsiang. Consequently, …

Computer Control Of A Pbx Washout Plant, Scott Cameron Sharp, Chung You Ho

Computer Science Technical Reports

A fully automated, computer controlled plant has been designed specifically for safe removal of plastic bonded explosives (PBX) from obsolete military munitions. This PBX washout plant consists of a two stage delivery system and robotically operated high pressure waterjet lance. The assigned task was to develop control packages for each component.

The first stage of the delivery system is a battery operated overhead trolley. Its control package consist of a dedicated computer, DC motor and custom positioning subprograms. The dedicated computer communicates through an infrared link to the operator's computer. This link was developed due to requirements of a hazardous …

Micro Database Management System Language, Karen Yingling Tam, George Winston Zobrist

Computer Science Technical Reports

There are two approaches to solve computational problems in a microcomputer environment:

1. Non-database approach: uses a high level programming language with non-database files as input and/or output files.
2. Database approach: uses the programming language embedded in the micro Data Base Management System(DBMS), with the database defined by the integrated database definition language as input and/or output files.

Adopting the appropriate approach in any single application may save cost and time. This paper compares the two different approaches while solving the same Control Section (CSECT) Interaction Hierarchy problem and suggests which to use when.

Premartensitic Anelasticity In Indium-Thallium Alloys., Manfred Wuttig, C. Y. Lei, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

The linear and nonlinear low frequency internal friction of In-24 at. pct Tl displays a Curie-Weiss type behavior in the temperature range above the transformation temperature. The critical temperature equals the martensite start temperature. It is proposed that the origin of the observed internal friction is the diffusion-controlled interaction of substitutional atoms with the premartensitic strain modulation, tweed.

Some Issues Of Thermodynamic Consistency In Binary Nucleation Theory, Gerald Wilemski

Physics Faculty Research & Creative Works

The "generalized" Kelvin equations used to determine the critical nucleus composition in some binary nucleation theories are shown to be thermodynamically inconsistent. Also, the surface tension calculated by the method of Flageollet-Daniel, Gamier, and Mirabel [J. Chem. Phys. 78, 2600 (1983)] is shown to be thermodynamically consistent with respect to the dynamic surface tension, contrary to the recent assertion of Spiegel, Zahoransky, and Wittig.

Deduction Of A Functional Dependency From A Set Of Functional Dependencies, James M. Richardson, Daniel C. St. Clair

Computer Science Technical Reports

This paper describes an algorithm called the Deduction Tracing Algorithm (DTA) which utilizes basic properties of functional dependencies from database systems and a modification of a tree search algorithm from artificial intelligence. The algorithm takes a set of functional dependencies, F, along with a specific functional dependency L → R as input and produces a list of functional dependencies from F that can be used to deduce L → R. The resulting algorithm is easily automated to provide relational database users with a tool for organizing their queries.

Intensity Blending Of Computer Image Generation-Based Displays, Elizabeth Scheppler Reidelberger, Daniel C. St. Clair

Computer Science Technical Reports

State-of-the-art combat simulators require a 360 degree field of view, allowing the pilot and radar intercept officer to have the same visibility in the simulator that they would experience in the aircraft. The sky/earth display must be computer - generated and displayed with a minimum of two channels to provide the most realistic display possible. The two channels of display come together in the dome, forming an equator, that must be as indiscernible to the aircrew as possible. To accomplish this, an algorithm has been developed for controlling the video output which makes the two separate channel displays appear as …

Theoretical Considerations Concerning The Separation Of Enantiomeric Solutes By Liquid Chromatography, Richard E. Boehm, Daniel E. Martire, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

A statistical thermodynamic theory of chiral solute retention and separation using chiral stationary phase high-performance liquid chromatography (CSP-HPLC) is formulated and applied in the limit of infinite dilution of solute to models of chemically bonded CSPs consisting of either chiral tetrahedral moieties or chiral molecular cavities intended to simulate a cyclodextrin CSP. Explicit expressions are derived for the corresponding separation factors and the likelihood of enantiomeric separation is investigated as a function of the multitude of possible interactions and retention modes for the enantiomers and CSPs considered. The separation factor reduces to a simple Boltzmann factor whenever a dominant retention …

The Role Of Dephasing In Some Recent Theories Of Quantum Localization, Paul Ernest Parris, Philip W. Phillips

Physics Faculty Research & Creative Works

We consider the transport of electrons or excitons through a random environment in the presence of constant site off-diagonal dephasing processes. It is shown that dephasing of this form will always defeat Anderson localization at long times. Some recent theories of quantum localization which depend upon such dephasing processes are, therefore, seen to be inconsistent.

Recruiting More Computer Science Students - What To Do After The "Glamour" Has Gone Away?, William E. Mcbride, James Calhoun, James Richards, Harriet Taylor, Frank Garnett Walters

Mathematics and Statistics Faculty Research & Creative Works

The moderator will first focus on the question: "Are enrollments actually declining in computer science programs across this country?" He will report the results of his surveys which indicate there has been a definite downturn in enrollment over the past two years. The panelists will then discuss what is being done at their schools to recruit students and to meet this new challenge of declining enrollments.

Recruiting More Computer Science Students—What To Do After The “Glamour” Has Gone Away?, William E. Mcbride, James Calhoun, James L. Richards, Harriet G. Taylor, Frank Garnett Walters

Mathematics and Statistics Faculty Research & Creative Works

The moderator will first focus on the question: "Are enrollments actually declining in computer science programs across this country?" He will report the results of his surveys which indicate there has been a definite downturn in enrollment over the past two years. The panelists will then discuss what is being done at their schools to recruit students and to meet this new challenge of declining enrollments. © 1988, ACM. All rights reserved.

Effects Of Transport Coherence On The Mutual Annihilation Of Excitons, Demet Gulen, Vasudev M. Kenkre, Robert S. Knox, Paul Ernest Parris

Physics Faculty Research & Creative Works

We report results of a theoretical investigation into the mutual annihilation of tight-binding excitons. The results are in apparent contradiction with intuitive expectations and provide corrections to expressions given by one of the present authors (V.M.K.) in an earlier analysis. A part of that analysis was based on a mapping of the dynamics of two mobile, mutually annihilating excitons onto the dynamics of a single exciton migrating in the presence of a fixed trap. We find that while this equivalence is valid for incoherent, randomly walking particles in an ordered system, it does not hold for an arbitrary degree of …

Implementation Of Cross Intersection Between Triangular Surfaces, Chaman Sabharwal, Thomas G. Melson

Computer Science Faculty Research & Creative Works

No abstract provided.