The spherical helical antenna is investigated as a new variation of the conventional helical antenna. The spherical helix is a wire antenna in a helix shape that is wound over a spherical surface instead of the standard cylindrical one. Analysis of this structure requires numerical methods and experimental measurements because its complex geometry makes it very difficult to develop analytic expressions for its radiation characteristics. The wire antenna code ESP, based on the method of moments, is used to calculate both the gain and phase of the electric-field components, E(} and E¢J' in the far field for spherical helices having between 3 and 10 turns. Several of these antennas were also constructed and tested on the Virginia Tech antenna test range. The numerical analysis and experimental measurements were performed over a wide range of frequencies corresponding to spherical circumferences of between 0.7 and 2.8 wavelengths. A literature survey of the conventional helical antenna is presented so that comparisons can be made with the spherical helix. The numerical and experimental results of the spherical helical antenna indicate that its behavior is markedly different than the cylindrical helix. It is a broad beam elliptically polarized radiator, in general, and operates over a relatively wide bandwidth. Under certain conditions, it is circularly polarized over a major portion of the main beam for a narrow bandwidth, a result which has potential applications. The behavior of the spherical helical antenna is not significantly affected by the number of turns and is discussed in this work for a few representative cases. / Master of Science

A method of reencapsulating native and reduced-cholesterol butteroil within natural membrane material and proteins of milk such that milkfat globule size and function resembled native cream as closely as possible was developed and evaluated. By replacing the native butteroil with reduced-cholesterol butteroil, an approximate cholesterol reduction of 80% was possible. Milkfat globule membrane material and proteins associated with the lipid phase were evaluated indirectly by measuring light scattering and phosphodiesterase activity in centrifuged reformulated raw cream. Functional stability of cream was measured by evaluating emulsion stability. Optimum conditions for reformulation using ultrasound included ratios of 1:1:1 (butteroil:buttermilk/aqueous phase:skim milk), emulsification time of 2.0 minutes for a 15 ml sample, and emulsification temperature of 42°C. Optimized conditions were used in scale-up reformulation of 750 ml samples replacing ultrasound with homogenization. Treatments included both native butteroil and reduced-cholesterol reformulated creams and unwashed natural cream as the control. Reformulation conditions included phase ratios of 1:1:1 (butteroil:buttermilk/aqueous phase:skim milk), homogenization temperature of 42°C, two-stage homogenization pressures of 500 psig/2000 psig, and product passed through the homogenizer twice. Much more membrane material and proteins became reenveloped into the cream phase with the homogenization process than with ultrasound. Stability of raw homogenized creams over 4 days at 2°C was evaluated by light scattering, phosphodiesterase, and emulsion stability. Overall, there were significant differences among treatments for light scattering and phosphodiesterase assays but not for emulsion stability. Significant differences among days within treatments indicated that the raw creams did change significantly over the time of storage. No differences were found among replications within treatments. Churn time, as a measure of functional stability, was measured on the first day after reformulation. No differences among treatments were observed. Practical applications of this reenvelopment method may include the use of butteroil in a wider range of reformulated dairy products including fluid milk, ice creams, and cheese products. Development of any full-fat reduced-cholesterol product will require a reformulation step unless cholesterol is directly removed from the food. / Master of Science

The philosophy of Friedrich Nietzsche is thought-provoking and enigmatic. This work is an exploration of three of the bulwarks of Nietzsche's philosophy and an attempt to trace their political implications. Analyses of Nietzsche’s concepts of the will to power, eternal return, and the Übermensch are presented in an effort to build a coherent vision of Nietzsche’s work. The will to power has been interpreted in many ways, and in this text I make the case that it is a drive for self-cultivation and finding one’s own direction in life. Eternal return is presented as a mythic idea which Nietzsche thought would spur people to live each moment as if they wished it would recur eternally, rather than judging their actions by future promises or past glories. The Übermensch is the Nietzschean individual who believes in eternal return and engages in self-cultivation through the will to power. There are interesting political implications which follow from this philosophical framework, which I discuss in the final chapter. Based on the analysis of the three concepts mentioned above, I argue that Nietzsche thought societal problems were never cured or even lessened by politics or any political theory. / Master of Arts

Two stack loss efficiency measurement methods, the Total Combustible Carbon (TCC) and Combustibles Meter (CM) methods, have been modified for use on masonry heaters. The applicability of the two methods has been verified with 6 tests on two masonry heaters. Each test starts with a cold heater and requires five firings to achieve two different burn rates. The efficiencies calculated for each firing are weighted according to burn rate following EPA Method 28 for wood heaters. The TCC Method uses carbon balances to calculate the chemical energy loss and the dry stack gas mass for calculation of sensible energy loss. The sensible loss that occurs during the off-period, when combustion of wood has stopped, is measured directly by injecting carbon dioxide in the stack and using it as a tracer gas to measure stack flow rate. In both methods the latent energy loss is calculated from wood moisture content and hydrogen content. The CM Method measures losses more directly and is considered the reference method in this work. The chemical energy loss is measured using a flame combustibles meter. The stack flow rate, which is used for the calculation of sensible loss, is measured directly using carbon dioxide tracer gas during both the on and off periods of the appliance. The overall average efficiencies measured by the two methods, in 5 tests on two different appliances, differed by a maximum of 1.7 percentage points of the fuel energy input. On the average they differed by about 1 percentage point. The results of a one-dimensional finite-difference model of the heat exchanger of one of the tested masonry heaters is compared against thermocouple-measured temperatures. For the 3 tests performed the model predicts the measured temperatures to within 12% during the first half of a firing cycle when the burn rate is high, and to within 5% during the second half of the cycle when the burn rate is low. / Master of Science

Several tanks have failed due to intolerable differential settlements, causing major problems in most cases. The objective of this study is to optimize the bottom plate of the tank so that the differential settlements are reduced to a minimum. Circular plates on an elastic half-space are investigated and the improvements in differential settlements are reported. The plates are loaded by a uniform pressure, and the effects of edge loads, edge moments, and elastic restraints at the edge are considered. A plate with two annular segments having fixed radii is investigated for optimal thicknesses. The plate is also optimized by varying both the radii and the thicknesses. Another plate with three segments is studied, varying the radii and the thicknesses. In all these cases, the plates are examined for a wide range of relative stiffnesses. For a specific relative stiffness, a plate with ten segments of fixed radii is studied. Also, the contact stress distribution is investigated for the case of the three-segment plate. During the study, the results are compared to a uniform plate. As an outcome, the differential settlement is significantly improved compared to the widely used uniform plate. / Master of Science

This purpose of this study is to construct computer models that can simulate national and regional development thus provide policy makers with a tool for policy experiments. This paper describes two models developed using the system dynamics methodology. The Development Model of the Philippines (DHP) is a national model organized into seven sectors: (1) Industrial Sector, (2) Environmental Sector, (3) Infrastructure Sector, (4) Social Development, (5) Demographic Sector, (6) Agriculture Sector, and (7) Employment Sector. Six policy experiments were performed using DHP: (1) Government Support of Agriculture Policy, (2) Government Allocation to Social Services, (3) Industrial Development Policy, (4) Infrastructure,(5) Environmental Protection Policy, and (6) Zoning Policy. The second model described in this study, called BUKID (from the filipino word for 'countryside'), is a multisectoral regional development model embodying the dynamics of rural-urban dependency with emphasis on the impact of investment on rice and corn farmers. It is composed of the following sectors: ( 1 ) Agriculture, (2 ) Industrial, ( 3 ) Demographic, and (4) Transportation. Four policy strategies that may be evaluated using BUKID are described herein. These are: (1) Land Reform, (2) Feeder Road Construction, (3) Crop Production Policy, and (4) Promotion of Agro-based Industries. / Master of Science

This work discusses the design of, and initial experiments with, a MIMO plate control testbed. This structure will be used as a development and standard comparison site for AVC and ASAC and is an extension of previous SIMO control investigations which used accelerometers and shakers. This portion of the development process of the MIMO plate control testbed is concerned with actuator and sensor materials and architecture, modeling approaches and requirements, and initial control experiments. The piezoelectric sensors and actuators are arranged on the plate to control the first five vibration modes. The sensors measure plate positions using a high impedance signal conditioning amplifier. The sixteen-channel design implements a band-pass filter to eliminate low- and high-frequency noise. The power amplification scheme chosen for the actuators uses low-gain amplifiers (~2.5 V/V) in series with a transformer (24:1) to deliver high voltages (up to 150 V) to the actuators. Low-pass smoothing filters (200 Hz cutoff) were added on the control inputs to reduce the high frequency content of the zero-order-held digital control signal. Initial methods for system identification of piezostructures are presented. Parametric frequency response approaches (modal analysis) were used and the model achieved is compared with measured data and purely analytic models. The empirical model was used in initial SIMO control experiments to demonstrate the testbed closed-loop performance. A LQG controller was implemented and produced 6 dB of suppression for the second mode for a 110 Hz disturbance. / Master of Science

The chemistry of Reissert compounds has been utilized to synthesize an activated difluorotetraketone monomer, 1 A-bis { 1-[ 4-(p-fluorobenzoyl)isoquinoly ] carbonyl } benzene (18). Two synthetic routes were explored in an attempt to find an efficient means of preparation. These routes entail preparation via a dibenzylic bis(isoquinoline) and a diketone bis(isoquinoline) system. These compounds were converted to their corresponding Reissert compounds. Reaction of the anion of the dibenzylic Reissert compound with p-fluorobenzaldehyde, followed by oxidation of both benzylic sites has produced the novel difluorotetraketone monomer. In addition, rearrangement of the dike tone Reissert compound has produced the novel difluorotetraketone monomer. This monomer offers a route to a novel family of poly(heteroarylene ethers). / Master of Science

The design of advanced, state-of-the-art turbomachinery requires accurate analytical tools for predicting rotor response and evaluating stability. One of the required tools is a reliable analytical code for predicting the performance of fluid-film bearings. This work presents an initial evaluation of a test rig for verifying such codes. This presentation includes background information on the techniques and terminology of fluid-film bearing analysis and two basic approaches to experimental evaluation of fluid-film bearings. To establish one such code, NPADVT, as a useful tool for evaluating the performance of the test rig, comparisons between six published, experimental evaluations of fluid-film bearings for static characteristics and the corresponding NPADVT analysis are presented. With the code thus anchored, and its limits established, experimental data generated with the test rig are compared to appropriate analyses and the test rig shown to be essentially functional. Finally, experimental static results for a pocket bearing generated with the test rig are presented and compared with analysis. / Master of Science

TRIAL 1 A preliminary study was conducted to evaluate growth, survival and feed conversion of reciprocal cross hybrid striped bass (<i>Morone chrysops</i> female x <i>Morone saxatilis</i> male) cultured in pilot-scale recirculating aquaculture systems. Hybrid striped bass were stocked in nine 12,500 liter recirculating systems at a mean density of 149 fish/m³. Mean weight at stocking was 40.6 g. Overall survival averaged 72.5%. One system experienced 100% mortality due to the loss of the recirculating pump. Three systems experienced significant mortalities in the middle of the study due to unknown causes. Survival was high, averaging 93.5%, in the remaining systems. Mean daily growth rate of 1 g per day and mean feed conversion of 1.67 compared favorably with that reported in the literature for hybrid striped bass. Slow start-up of new biofilters led to a restricted feeding regime and limited growth. Mean fish weight at harvest averaged 262.1 g with total biomass in the tank averaging 452.57 kg. The recirculating system maintained water quality within ranges adequate for good growth, but the stocking density may have surpassed the systems maximum capacity. TRIAL 2 Results from Trial 1 indicated a need to reduce stocking densities. In Trial 2, three densities of reciprocal cross hybrid striped bass, high (144 fish/m³), medium (72 fish /m³) and low (36 fish/m³) were stocked in eight pilot-scale recirculating systems (12,500 L) and evaluated over 224 days. At stocking, mean weights averaged 34.9, 50.8, and 43.4 g for the high, medium and low treatments, respectively. Fish were hand fed a high protein (44%) floating pellet twice daily. Final weights averaged 412.2 g, 541.1 g, and 676.1 g in the high, medium and low density treatments, respectively. No difference in mean weights were detected between the high and medium densities, but those in the low density were significantly greater (p < 0.05) than the medium and high densities. Total biomass was significantly different (p < 0.05) between treatments at the end of the study and inversely related to mean weight gain, averaging 733.8 kg in the high, 483.3 kg in the medium, and 297.9 kg in the low density treatments. The water quality parameters measured were similar among treatments and adequate for good growth. Feed conversions averaged 1.43 and were not significantly different between treatments. Survival averaged greater than 95% in all treatments. The results of this study demonstrated that hybrid striped bass can grow from fingerling to market size in 224 days in recirculating systems at densities of 36 and 72 fish/m³. If environmental conditions are adequately maintained, it is anticipated that higher densities could reach market size in the same time period. Overall results indicate that hybrid striped bass have good potential for culture in recirculating aquaculture systems. / Master of Science