Fiber optic sensors offer many advantages over conventional sensors, including; small size, low weight, high strength and durability. Standard silica optical fibers are limited by the material properties of silica. Temperatures above 700°C and other harsh environments are incompatible with standard optical fiber sensors. Sapphire fiber sensors offer another option for fiber optic sensing. Sapphire fibers are limited by the material properties of sapphire, which include high melting point, extreme hardness and imperviousness to chemical reactions and radiation. These properties coupled with the advantages of conventional fiber optic sensing make sapphire optical fiber sensors a good candidate for sensing requirements in harsh environments. We investigate the potential for the use of sapphire fibers as sensors. Two sensors are developed based on widely different techniques. Results from preliminary tests of each are given. / Master of Science

Two experiments were designed to study efficacy and uptake and translocation of an ester formulation of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) in four solvents, aromatic solvent, aliphatic solvent, vegetable oil, and kerosene following stem applications to red maple (Acer rubrum), white oak (Quercus alba), and Virginia pine (Pinus virginiana). Another objective was to explore correlations between efficacy and uptake and translocation. Additional objectives included examining the influence of concentration, dose, and stem diameter on efficacy and the influence of bark thickness and season of treatment on uptake and translocation. Concentration ranged from 0.25 to 1 lb a.e./gallon in the efficacy study and was 1 lb a.e./gallon in the uptake study. Dose ranged from 0.4 to 2 ml/cm of stem diameter in the efficacy study and was 0.15 ml/cm of stem diameter in the uptake study. Efficacy evaluations were made 14 months following treatment in June. C¹⁴- triclopyr was used to determine uptake and translocation. Saplings in the uptake study were harvested three weeks following treatments in February, May, and July. Aliphatic solvent, vegetable oil, and kerosene treatments resulted in excellent crown volume control, largely independent of concentration, dose, and stem diameter. Aromatic solvent gave poorer results, dependent on concentration, dose, and stem diameter, except among the maples. Herbicide uptake with the vegetable oil treatment was greatest. The other solvents provided similar levels of uptake. Uptake was greatest among the maples, the thinnest-barked species, and about equal in the oaks and pines. Discrepancies between solvent differences in the efficacy and the uptake studies may have been, in part, a consequence of smaller doses used in the uptake study along with conditions which likely promoted greater solvent evaporation than those under which the efficacy study was performed. Faster evaporation of the kerosene and aliphatic solvents may have reduced their penetration of the outer bark while slower evaporation of aromatic solvent and vegetable oil likely had less influence on their penetration. Stem diameter correlated negatively with crown volume control, despite basing dose on stem diameter, suggesting that the square of diameter, or stem volume, may be a more appropriate basis for determining doses. Uptake correlated negatively with bark thickness. Uptake did not vary significantly among seasons but translocation did. Movement to the leaves occurred following the May and July treatment but virtually none to leaves or buds following the February treatment. The high degree of sprouting which occurred among saplings in the May treatment compared with none among saplings in the July treatment would suggest that downward translocation of herbicide was greater in July. / Master of Science

Control strategies for the German cockroach, Blattella germanica (L.), are usually based on the application of liquid insecticides in or near infested harborages. Cockroach mortality occurs when they are exposed to insecticide residue by walking on insecticide-treated surfaces. Cockroach walking depends on the three pairs of legs. Only tarsal pads and arolium on each leg are involved in traveling and picking up insecticide residue. The total contact area at each step was 0.1879 mm² and 0.1771 mm² for laboratory susceptible (VPI) and field-collected (RHA) cockroach strains, respectively. There were no significant differences (P > 0.05) in the walking distance in two steps among three legs, or between the two strains. However, the walking movement rate greatly influences the amount of insecticide accumulated on tarsal pads in a distinct time period. RHA-strain cockroach walked a significantly (P < 0.05) greater distance than VPI-strain on untreated and 10 ug/cm² of cypermethrin treated glass plates. RHA-strain cockroaches picked up significantly (P < 0.05) more cypermethrin than VPI-strain in 5 min, but there was no difference when exposed for 30 movement units. Knockdown time was significantly correlated (P < 0.05) to estimated dose transfer in 0.025 μg/cm² and 0.049 μg/cm² treatments for the VPI-strain, and in 0.245 μg/cm² and 0.392 μg/cm² for the RHA strain. Cockroach knockdown time and mortality were determined by cockroaches walking on different numbers of cypermethrin droplets on treated glass plates. Insecticide dose could be reduced from 10 μg/cm² to 0.025 μg/cm², but resulted in increasing the KT₅₀ from 5.4 min to 15.9 min in VPI-strain cockroaches. To achieve 50% cockroach knockdown, a VPI-strain cockroach must walk on at least 33 droplets (130 μm in diameter) of 0.1% cypermethrin; an RHA-strain cockroach must walk on at least 3174 droplets. High insecticide dosage increased the amount of antennal grooming in VPI-strain cockroaches and stimulated leg grooming in RHA-strain. Walking movement activities decreased in response to increased antennal and leg grooming. / Master of Science

The synthesis of poly (butyl vinyl ether) and poly (butyl vinyl ether 2-chloroethyl vinyl ether) random copolymers was accomplished through the use of the aluminum hydrogen sulfate catalyst (AHS). In this system, AHS acts as a heterogeneous catalyst in the cationic polymerization of vinyl alkyl ethers. Highly isotactic polymers (greater than 70%) have been prepared and characterized by IH and 13C NMR. DSC characterization of poly(butyl vinyl ether) also reveals that these polymers are semicrystalline. Gel permeation chromatography characterization and intrinsic viscosity data of poly(butyl vinyl ether), and poly{butyl vinyl ether-2-chloroethyl vinyl ether) homopolymers and copolymers indicate fairly narrow polydispersities, and very high molecular weights. A study of this copolymerization by lH NMR revealed that the 2-chloroethyl ether monomer was being incorporated along the chain with the greater percentage of the 2-chloroethyl vinyl ether monomer near the chain ends. Reactions on the pendent chlorine group are currently under investigation in our laboratories. It is anticipated that a range of pendent functional groups can be obtained. / Master of Science

The purpose of this thesis is to develop a formal methodology for determining the loads occurring in the members of an adaptive truss due to both gravity and acceleration. This force analysis can be used as the basis for a design code which will provide truss member dimensions and actuator characteristics. Three different truss structures are considered. The first is a planar, triangular truss consisting of one actuated member and two fixed length members. The second structure is a spatial, double-octahedral truss with three active members and eighteen fixed length members. The third structure is a truss consisting of several double-octahedral bays connected together as a chain. For each structure, the active link motion is first simulated and the position, velocity, and acceleration history of each of the member connecting points is calculated. The dynamic equations of motion for each member are developed and combined to form a system of equations describing the motion of the entire truss. These equations are then solved to find the forces occurring at each node. Once the forces are determined, the internal forces in each member can be found, and the resulting stresses are calculated. The members are also checked for buckling using Euler buckling theory. The stress calculations are checked against experimental values and show good agreement for both static only and static and dynamic loading. / Master of Science

A thin-film gage was designed, constructed, and tested for the measurement of skin friction in steady and non-steady flows. This direct-force-reading gage is designed to have a high frequency response (> 1 kHz), high temperature capability (800 K), and full directional sensitivity in both subsonic and supersonic flows. The thin-film gage consists of a floating element attached to the wall surface by four tabs. The floating element consists of a thin metal film mounted flush to the wall surface. Shear forces acting on the thin-film surface cause strain concentrations to develop in the attachment tabs where strain sensors are located. The shear forces are related to the differential output of the strain sensors located on each of the orthogonal axes of the thin-film gage. A large-scale (10X) prototype was constructed and statically calibrated for actual shear stress measurements. Subsonic, steady flow tests demonstrated the directional sensitivity capability and gave reasonable shear measurements compared to Preston tube results. Subsonic, non-steady flow tests demonstrated the high frequency response of the thin-film gage. Supersonic flow testing was performed which identified design flaws in the original design which were corrected in the development of an actual-size (1X) prototype. Survival of the thin-film gage in a supersonic environment was demonstrated with the 1X prototype. Finally, the 1X prototype was statically calibrated for measurements of shear stress in a supersonic environment. / Master of Science

Log phase cells of Listeria monocytogenes Scott A were heat shocked in Trypticase Soy + 0.6% Yeast Extract broth at 40, 44, and 45°C for 3, 10 and 20 min at each temperature, followed by heating at 55â C for 50 minutes in order to determine an optimum heat shock response. Most heat shock temperatures significantly increased thermal resistance (p < 0.05). Increasing heat shock temperature and time allowed the organism to survive much longer at 50 to 65°C than nonheat shocked cells. The optimal heat shock condition was 45°C for 20 min where D-values at 55°C increased 2.3 fold in non-selective agar and 1.6 fold in selective agar in comparison to non-heat shocked cells. However, cells heat shocked at 48°C for 10 min gave more consistent results; these cells were heated at 50, 55, 60, and 65°C to determine a z-value. Although D-values notably increased due to heat shocking, z-values remained constant regardless of the plating medium. When aerobically heat shocked cells (45°C for 10 min) were plated on a non-selective or a selective medium, a 1.4x increase in D-value was observed when enumerated under strictly anaerobic conditions. Aerobically heat shocked cells (48°C for 10 min) added to shrimp samples retained the increased heat resistance at 55°C when enumerated on a nonselective medium compared to the non-heat shocked cells. Heat shocking conditions may be created in pasteurization or minimal thermal processing of foods allowing increased heat resistance of pathogenic and spoilage microorganisms. / Master of Science

Three methods of indicating active (linked) words in hypertext documents were investigated. The Methods consisted of font-manipulation techniques (such as shadowed and outlined text), word-enclosure techniques (variations of a box and pseudo-brackets around the word), and "punctuation-like" icons (located directly above the first letter of an active word). Two Cues were nested within each Method, yielding a total of six Cues. Twenty-four subjects (12 males and 12 females) performed reading tasks and visual search tasks to evaluate each of the three Methods and six Cues. A hierarchical, within-subjects experimental design was used, employing a completely counterbalanced order of treatments. The study consisted of two experiments. For Experiment 1 (reading tasks), participants read Tinker (1955) passages and identified an inappropriate word in each passage. Passages contained either one of the six Cues or no Cues (control condition). The times taken to read each passage and locate the target word, as well as the number of errors made, were recorded. For Experiment 2 (visual search tasks), participants scanned text fields and located and counted the number of active words contained within each text field; again, the times taken to locate all active words and the number of errors made were recorded. For both experiments, participants rated Cueing Methods along various dimensions and selected a preferred Cue and Method for the tasks performed in each of the two experiments. For reading tasks, no single Cueing Method yielded significantly shorter reading times than any other Method. Similarly, no particular Method was preferred by significantly more participants than any other Method. However, user ratings were more favorable for Icons than for Enclosures or Character Styles. In addition, Character Styles were consistently rated as being highly distracting for reading tasks. For visual search tasks, Character Styles yielded shorter search times (<i>p</i> < 0.05) as well as significantly more favorable salience ratings. Participants also preferred the Character Styles significantly more often than either Enclosures or Icons for locating linked words. The number of errors produced for both experiments was very low (less than 2%) and there were no significant differences in errors across Methods or Cues. This finding is not unexpected considering the low level of difficulty for the reading and search tasks. Based on the results of both experiments, Icons are the recommended Method for indicating linked words in hypertext documents. Icons provide moderate perceived readability (reflected in subjective ratings, though not in reading times or preferences), whereas Enclosures were not sufficiently salient and Character Styles were perceived to have degraded text readability. A discussion of a wide variety of techniques which either are currently used in existing hypertext systems or could potentially be used is included in the Literature Review section. The issue of trade-offs between Cue salience and obtrusiveness is addressed in the Discussion. / Master of Science

This thesis describes the wildlife resources of Senegal and a systems approach to how those resources can be managed. Based upon my 20 years experience in the Forest Service and the National Park Service, I made investigations through the literature, courses, seminars, conferences and interview in the United States and Senegal. The aim of the investigations was to gather wildlife resource-based data from Senegal, Africa, the United States, and other countries. This thesis is an effort to synthesize what is known about the forests and wildlife of Senegal and to describe a wildlife resource management system. The system is hypothesized to be a basis for organization, operations, and planning for the long-range management of the wildlife resources in the forests and shrublands of Senegal. The project described the country area. It described 4 key subsystems of the greater system to show what resources exist, and what is a system, and how a single pattern of analysis and design can result in efficiencies and increase productivity. The key subsystems are: (1) an Elephant Subsystem, (2) the National Park Subsystem, (3) a Hunting Areas Subsystem, (4) a Nature-Based Tourist Subsystem. The emphasis in each is on wildlife resources management. It is believed that most ideas developed in this study could be applied in the 8 Sahelian nations of West Africa and other African countries. / Master of Science

The objectives of this research are to take advance steps to assess the potential impacts of sea level rise on our nation's estuarine environments and water resources management. Specific engineering solutions to control salinity intrusion are studied. Structure measures such as construction of tidal barriers, tidal locks, and through long term stream flow augmentation are investigated for their suitability. Quantification of the extent of the impacts is accomplished by means of computer model simulations. A laterally integrated two-dimensional. time dependent. finite difference numerical model is used to study time-varying tidal height. current and salinity. Through a selected estuary. parametric studies on scenarios of projected sea level rise, stream flow, channel roughness, change in cross-section profile, etc. are performed in order to have an in-depth understanding of estuarine processes for cases such as present condition versus future sea level rise, with or without control measures. The results of the parametric studies are summarized and engineering applications of individual control methods are discussed. / Master of Science