In this thesis, a system for studying human/computer interfaces is introduced. The human/computer interface provides several features, the most noteable of which is TOKEN COMPLETION. These features permit the user to define and/or redefine command tokens, define and/or delete synonym and noiseword tokens, and to establish a terminal environment. The terminal environment includes the ability to specify automatic comment blocking, token look-ahead, and to control the source of data input (keyboard, VMS file, or I/O buffer). The ability to token complete is based on a forest of generalized trees used to implement dynamic deterministic finite state automata (DDFA). These trees are built during IPL and loaded with command, synonym, and noiseword tokens, all of which are stored in separate VMS files. Synonym and noiseword translation is carried out in the lexical analysis process, thereby negating any need to specify these functions in the grammar of the language. Insertion and deletion into the forest may be executed at any time, permitting the dynamic definition and deletion of synonyms and noisewords. During synonym and/or noiseword definition, lexical analysis switches to a deterministic finite state automata (DFA) mode of operation. Upon completion, lexical analysis reverts to DDFA mode. A sample grammar is provided in the APPENDICES. The lexical analysis process is not tied into this grammar but rather is very general and will process any tokens stored in the command, synonym, and noiseword files. The sample grammar is LALR(1). / Master of Science

Two distinct forms of Red Crossbill (Loxia curvirostra) bred sympatrically in the southern Appalachians in 1983. The forms differed significantly in vocalizations and bill and body size, and the members of each of 20 male-female pairs were of the same size class. One of the forms from Virginia has been tape recorded in western North America in 1983 and in previous years, showing that vocal classes are not local dialects. Evidence presented here suggests that forms of Red Crossbill are not subspecies as is currently recognized, and that they behave as biological sibling species. / Master of Science

Field collections of grasshoppers (Orthoptera: Acrididae, Tetrigidae, and Tettigoniidae) from twenty hayfield and pasture sites in twelve counties in Virginia were made in 1979 and 1980. Fifteen Acrididae, two Tetrigidae, and six Tettigoniidae species were found among the 20,793 grasshoppers collected. Melanoplus femurrubrum femurrubrum (DeGeer) dominated the acridid fauna in both years, comprising 76.0 and 86.97 in 1979 and 1980, respectively. Two collection methods, sweepnetting and drop trapping, were used. It was assumed that the drop trap gave an absolute estimate of population densities and that discrepancies between the two collections were due to failure of sweepnetting to reliably sample the complex. Sweepnetting was found to bias against Acrididae in favor of the tettigoniidae in the complex studied. With species grouped by feeding preferences (quilds), sweepnetting sampled head (inflorescence) feeders above mixed-forb feeders, and mixed-forb feeders above grass feeders. Compared with other Acrididae, M.f. femurrubrum was over-represented in sweepnet samples above the composite of the other acridids. Within its quild its representation did not differ from the drop trap samples. Differences in the composition of the species complex from site to site were examined according to quilds based on diet, and were correlated with measurable properties or the vegetation. The proportion of head feeders was positively correlated with the plant height. Mixed-forb feeders were negatively correlated. Other vegetation properties (grass/forb ratio and percent of ground cover) were themselves highly correlated with plant height, and yielded no patterns that were as strong as those with plant height. / Master of Science

The relationships between ferric iron content and the P-T-fH₂ conditions of formation were examined for two biotite compositions: annite (K₂Fe₅Al₄Si₅O₂₀(OH)₄) and siderophyllite (K₂Fe₆Al₂Si₆O₂₀(OH)₄). The synthesized phases were annealed at fixed hydrogen fugacities using both the solid oxygen buffering technique of Eugster (1957) and the H₂ buffering technique of Shaw (1967). Resulting hydrogen fugacities ranged from 0.004 bars (at T = 400°C, P_T = 2 kb) to 51 bars (at T = 750°C, P_T = 1 kb). Ferrous iron contents of the annealed biotites were determined by wet chemical analyses. Total iron was determined by microprobe analyses to be equal to the stoichiometric values. The data confirm the predictions of Hazen and Wones (1972, 1978) that: 1) There is a structural limit imposed upon the Fe³⁺ content of annite due to the misfit between the octahedral and tetrahedral layers. This misfit requires a minimum of 11% Fe³⁺ in annite. 2) The steric misfit in annite can be corrected by a substitution of Al^vi + Al^iv for Fe^vi + Si^iv, so that there is no Fe³⁺ in siderophyllite at high hydrogen fugacities. A model relating Fe³⁺/Fe²⁺ ratios, fH₂, and T is proposed. The model accounts for the amount of Fe³⁺ needed to correct the steric misfit in annite and allows for variation in Fe, Al, and Mg contents among biotites. A simple oxidation-reduction reaction is used to relate changes in the non-steric ferric iron to hydrogen fugacity and temperatures for the Fe-Mg-Al biotites. The equilibrium constant for the reaction can be expressed as: (1) log K= 3607.2/T - 4.47 where, depending on composition, K is expressed as follows and R is a constant proportional to the U structurally required iron. (2) Al^vi/0.3 + Mg/0.72 ≥ 1, K = Fe³⁺/Fe²⁺ fH₂^1/2 (Al^vi + Mg ≥ 1) (3) Al^vi/0.3 + Mg/0.72 > 1, K = Fe³)/Fe²⁺ - (1-Al^vi-MG) fH₂^1/2 (Al^vi + Mg < 1) (4) Al^vi/0.3 + Mg/0.72 < 1, K = [Fe³⁺/(Fe²⁺ - (1-Al^vi-MG)) -0.185] fH₂^1/2 (Al^vi + Mg < 1) / Master of Science

Surface and bulk properties have been studied in terms of composition and morphology of siloxane containing block copolymers and their blends with homopolymers. X-ray Photoelectron Spectroscopy (XPS) has been used to obtain the compositional information from the top 60 angstroms or so at the surface. Transmission Electron Microscopy (TEM) was utilized to probe the bulk morphology. An attempt is made to compare the bulk and the surface and find possible mechanisms governing them. It is found that solvent-cast neat block copolymers have a uniform layer at the surface that is rich in siloxane whereas their bulk has a microphase-separated domain structure. In case of blends, siloxane enrichment is quite pronounced even at bulk concentrations as low as 0.05% w/w siloxane. Amount of surface siloxane as a function of bulk content is studied with the help of XPS. At the same time, the bulk morphology of these blends is studied by TEM. The changes occurring in the surface and the bulk are found to have similar patterns. It is shown that the observed surface behavior may be related to the bulk morphology. Molecular weight of the blocks in the copolymers is found to be a very important parameter governing both the surface and the bulk properties in the neat copolymers as well as their blends. / Master of Science

In this study, an instrument (Hutchins Behavior Inventory or HBl) was designed to measure components of the TFA System. The HBI was given to 328 college psychology students to measure reliability. Internal reliability scores for thinking, feeling and acting ranged from .780 to .980; test-retest reliability scores ranged from .710 to .930. / Master of Arts

The ability to generate a crossflow vortex pattern on a swept flat plate, that is typical of swept-wing flows, is presented. A swept flat plate with an elliptic leading edge is mounted vertically in the VPI&SU Stability Wind Tunnel opposite to a swept wall-bump; along with floor and ceiling fairings that duplicate the inviscid streamlines. The resulting pressure gradient over the plate produces a crossflow vortex structure. Detailed three-dimensional measurements, made within the boundary layer using hot-wire anemometry, are supplemented with different flow-visualization techniques. Freestream measurements are carried out to find the variation of the velocity vector along the model and comparisons are made with the theory showing good agreement. Spanwise measurements are conducted within the boundary layer and show a steady vortex structure. Boundary-layer profiles are taken using both a straight-wire and slant-wire probe in order to obtain the variation of the velocity vector in the region. The components parallel and perpendicular to the freestream velocity vector are extracted, and the perpendicular component is called the crossflow profile. These profiles are compared to the theory. Shape factors and crossflow Reynolds numbers are obtained and analysed. Two types of flow-visualization techniques are used in the tests. One is the "smoke-wire" technique, where streaklines inside the boundary layer are visualized. This method is not successful in visualizing any vortex structure in the boundary layer. Therefore, the second method was employed: a sublimation technique using trichlorethane and naphthalene is used to visualize the variation of the surface shear stress. A uniform pattern of streaks aligned approximately in the potential flow direction is observed. This pattern has a wavelength on the order of one centimeter which agrees quite well with the theoretical model. / Master of Science

In this thesis we present new results for the makespan and the flowtime in a flow shop without intermediate storage between machines. We consider m machines and n jobs with random processing times. Since there is no intermediate storage between machines, a job which has finished processing at one machine may have to stay at that machine until the next machine is free. This phenomenon is known as blocking. Our goal is to select the optimal schedule; in our case, the schedule which in some sense minimizes the makespan or the flowtime. Makespan is the total time required to process a set of jobs and flowtime is sum of all the times at which jobs are completed. Our results require various stochastic orderings on the processing time distributions. Some of these orderings minimize the expected flowtime or expected makespan, and some stochastically minimize the makespan. The stochastic minimization results are much stronger. The optimum sequence in these cases not only minimize the expected makespan, but also maximize the probability of completing a set of jobs by time t for any t. Our last result resolves the conjecture of Pinedo (1982a) that in a stochastic flow shop with m machines, n-2 deterministic jobs with unit processing time, and two stochastic jobs each with mean one, the sequence which minimizes the expected makespan has one of the stochastic jobs first and the other last. We prove that Pinedo's conjecture is almost true. We prove that either the sequence suggested by Pinedo or a sequence in which the stochastic jobs are adjacent at one end of the sequence minimizes the expected makespan. Our result does not require the stochastic jobs to have an expected value of one. Furthermore, we show that our result cannot be improved in the sense that in some cases one sequence is strictly optimal and in other cases the other is strictly optimal. / Master of Science

The present study attempted to validate modified versions of laboratory measures of behavioral impairment from alcohol for use in the field. A total of 195 students at various BAC levels, participated during two outdoor university-sponsored events. In addition to taking nonbehavioral measures of impairment, each subject was asked to perform and evaluate a reaction time task, balance test, and give a verbal index of impairment. The actual BAC of each subject was determined using a breath-alcohol testing machine. The results indicated that self-reported measures of impairment were the best predictors of BAC. Of the behavioral measures, reaction time and body balance performance accounted for the highest portion of the variance in predicting BAC. Subjects reported that actual BAC feedback would most likely result in behavior change, followed by performance on the progressive body balance and reaction time tasks. It was noted, however, that as BAC increased, poor test performance was less likely to result in behavior change. The need for continued research into behavioral measures of alcohol impairment are discussed as a means of promoting third-party intervention and"socially responsible drinking". / Master of Science

A method was investigated to synthesize diamonds at atmospheric pressure without the use of diamond seed crystals. The method was first proposed by Burton in 1905 and appears to have been lost in the literature. The procedure is based on Ostwald's principle of the formation of metastable, intermediate crystals en route to a more-stable final product. Carbon was dissolved in a lead-calcium alloy and was later precipitated out of the melt by the removal of calcium with steam. The calcium was used to increase the solubility of carbon in lead. Reaction temperatures between 775 K and 1025 K were used. The resulting precipitate, analyzed by both chemical and physical means, was found to be well-crystallized graphite. No diamond formation was found to occur. / Master of Science