The potential harmful effects of agricultural chemicals on human health and the Chesapeake Bay have led to the need to identify economical practices that limit the chemicals impact on surface and ground water contamination. The agricultural practices of the Atlantic Coastal Plain in Virginia have resulted in many bottom land areas of forests and wetlands being left uncultivated, while the upland areas are being utilized for intensive agriculture that may act as a source of chemicals in the environment. The capacity of a riparian wetland to act as a buffer zone between an intensively managed agricultural field, located in Westmoreland Co., Virginia, and a riparian stream that borders the field was investigated in this study. The ground-water chemistry was evaluated using water samples from ground-water wells and the stream. Seventeen ground-water wells were installed and three surface-water sample locations were stablished. Samples were collected bi-weekly for an 18 month period. Samples were analyzed for nutrient and pesticide constituents. A tracer study was used, unsuccessfully, to determine flowrates at the study site. A ground-water model was used to estimate flowrates at the study site using measured site characteristics. Pesticides were not detected in samples. Results from this study revealed that the elevated levels of nitrate in ground-water, resulting from fertilizer application, were reduced by 48% by the riparian zone, from an average level of 9.0 mg/l in the agricultural field to an average level of 4.68 mg/l in the stream. Reductions of nitrate were as great as 57% between ground-water samples from the agricultural field and ground-water samples from the riparian wetlands. The reduction in nitrate concentration was less than has previously been reported by other investigators, primarily due to differences in site characteristics. This study demonstrates the role that buffer zones along streams may play in reducing the influence of agricultural fertilizers on surface waters and the need to manage riparian forests as a beneficial part of the agroecosystem. The data collected from this study will aid in the proper design and implementation of riparian forest corridors as decontamination zones. / Master of Science

This thesis was originated by the debate over the effect of urban growth boundary on the value of vacant land. The case of Virginia Beach was studied. In 1979 a green line policy was enacted in this city. This study was dedicated to assess the effect of this policy on the value of the vacant land. A hedonic price model was used to isolate the importance of various characteristics of land in price determination and a simulation equation model was performed to obtain the total change in land value after the green line policy was introduced. / Master of Science

An investigation was performed to determine the aerodynamic and acoustic performance of the bifurcated 2D supersonic inlet during takeoff and approach flight conditions, and to compare these results indirectly to those of the axisymmetric supersonic inlet. The comparison is not direct since the centerbody position of the bifurcated 2D inlet is set at takeoff and approach position, where as the axisymmetric inlet’s centerbody position is not. The axisymmetric inlet’s aeroacoustic performance data is to serve as a reference to evaluate the bifurcated 2D inlet’s aeroacoustic performance. The inlets used in this study are 1/14 scale models designed for high speed civil transport aircraft. To provide the typical noise signature of a high bypass turbofan engine, a 10.4 cm (4.1 in.) turbofan engine simulator was used in conjunction with the supersonic inlets. The experiment was tested under static conditions. Steady state measurements of the inlet’s flow field and far field acoustic measurements of the fan noise were made to evaluate the aerodynamic and acoustic performance of the inlets respectively. The results show at approach fan speed (60 PNC), the bifurcated 2D inlet reduced circumferential distortion at the fan entrance by a factor of 1.7 compared to the axisymmetric inlet tested with auxiliary inlet doors closed and 1.5 compared to the axisymmetric inlet tested with auxiliary inlet doors open. At takeoff fan speed (88 PNC), the bifurcated 2D inlet reduced circumferential distortion by a factor of 1.5 compared to the axisymmetric inlet tested with auxiliary inlet doors open. The overall inlet total pressure recovery for the bifurcated 2D inlet at approach fan speed (60 PNC) is 97.6% which is 3.2 % higher than the axisymmetric inlet (94.4 %) with auxiliary inlet doors closed and 1.5% higher than the axisymmetric inlet (96.1%) with auxiliary doors open. Acoustic measurements were taken in a far field sector, 0°-110° from the inlet’s centerline axis. At takeoff fan speed (88 PNC), the bifurcated 2D inlet reduces the blade passing tone by an average of 9.6 dB over the (0-1 10°) far field sector compared to the axisymmetric supersonic inlet with the auxiliary inlet doors open. At approach fan speed (60 PNC), the bifurcated 2D inlet reduced the blade passing tone by an average of 8.8 dB compared to the axisymmetric supersonic inlet with auxiliary inlet doors open. When the axisymmetric inlet was tested with it’s auxiliary inlet doors closed at approach fan speed (60 PNC), the ‘choking effect’ changed the radiation pattern of the axisymmetric inlet such that only the rear sector far field (60°-110°) of the bifurcated 2D inlet is quieter than the axisymmetric inlet. On average, there was no appreciable difference in the blade passing tone for either inlet over the 0°-110° far field sector at this fan speed. / Master of Science

A considerable body of knowledge has been accumulated regarding the effects of participation, but little research has dealt with the effects of participation in the development of a measurement system. This research tests the effect of participation on the development of a workshop evaluation process by identifying trust as a key variable and quantifying the effect of participation on trust. (In this research, a workshop evaluation process is considered to be a type or example of a measurement system.) The researcher believed to the extent participation in the development of a workshop evaluation process contributed to the amount of information a participant had regarding the system and to a feeling of commitment and control on the part of the participant, positive effects of participation would generalize to others areas and lead to an increase in trust. During the study, fourteen workshop leaders were divided into a control and treatment group. The treatment group participated in an one-hour session to develop the workshop evaluation form; the control group did not. All participants were surveyed on trust after the workshop evaluation form was used to evaluate each presentation. No significant differences in trust of the workshop evaluation process, other workshop leaders, or the people who managed the workshop evaluation process were found between the control and treatment group participants. The attenuation of the data was attributed to the small sample size, short length of participation, and questions regarding the validity of the trust instrument. / Master of Science

This research was concerned with the processing and properties of composites of high density polyethylene (HDPE) and thermotropic liquid crystalline polymers (TLCPs). Strands of HDPE reinforced with TLCPs were generated using a novel dual extruder mixing technique. It was shown that the strength and modulus of the strands improved with increased strand drawing. Post-processing of the blended strands was done by means of compression and injection molding. It was observed that when the fiber aspect ratio dropped, the composite mechanical properties decreased. When pregenerated fibrils were maintained during injection molding at temperatures above the matrix melting point, but below the TLCP melting point, microcomposites were obtained. Microcomposites generated at the lowest temperatures had higher tensile properties than found for in situ composites and similar to glass reinforced HDPE. At 170°C the pregenerated fibers were no longer deformed during injection molding and high aspect ratio fibrils were maintained. The fiber orientation and addition of a compatibilizer were also studied. This study shows it is possible to extrusion blend HDPE with TLCPs and by optimizing the post-processing conditions, to obtain microcomposites with better properties than in situ composites. / Master of Science

An analytical model has been developed to study the potential of active noise control techniques for reducing radiated tonal inlet noise from turbofan engines. The analytical model consists of multiple control sources placed in the periphery of the engine inlet duct which inject anti-noise into the duct to destructively interfere with the sound field generated by the fan. The development of the analytical expressions of the radiated sound fields due to both the fan disturbance and the control sources is based on duct modal expansion. Numerical analyses are presented for different system configurations of secondary control sources and error sensors. Two error sensing strategies are considered in this work. The first approach uses microphones placed in the acoustic far field. The second sensing technique consists of placing distributed error sensors in the engine inlet. Attenuation of the radiated sound field is accomplished using a multichannel feedforward control approach. Control signals are calculated to minimize the pressure disturbance at desired error sensor locations and are then used to determine the controlled radiated sound field. The performance of selected system configurations are discussed and the sensitivity to system parameter variation to the control of inlet noise is explored. Reductions in the radiated sound power level of 4 to nearly 28 dB is demonstrated. It is also demonstrated that for global attenuation of the far field pressure multiple axial arrays of control sources are required. The model can be used to evaluate performance envelopes for various system configurations including sensitivities to error sensor and control source locations, control channel configurations and the effects of mean flow within the inlet duct. The model can also be extended for use in design optimization. / Master of Science

The hydrogenation of unsaturated carbon-carbon bonds catalyzed by transition metal hydrido complexes has received considerable attention in the literature. Environmental interests have placed considerable emphasis on switching these processes into aqueous media. The dimeric complex [Ir(COD)Cl]₂ (COD = 1,5-cyclooctadiene) has been found to undergo bridge-splitting reactions with bidentate phosphine ligands to produce coordinatively unsaturated, 16 electron complexes of the form [Ir(COD)(P-P)]Cl (P-P = bidentate phosphine). Two bidentate ligands were examined: 1,2-bis(dimethylphosphino)ethane [DMPE] and 1,2-bis(diethylphosphino)ethane [DEPE]}. These compounds have been found to be both water soluble and reactive towards molecular hydrogen at room temperature, qualities that make them ideal for serving as catalysts for the aqueous hydrogenation of unsaturates. Water-soluble ligands were also allowed to react with [Ir(COD)Cl]₂. In these cases, the product was analogous to the [Ir(COD)(PMe₃)₃]Cl complex. Two water-soluble phosphines were examined: 1,3,5-triaza-7-phosphaadamantane [PTA] and tris(hydroxy-methyl)phosphine [THP]. When these complexes were hydrogenated in water, the PTA complex underwent an oxidative addition of molecular hydrogen with the loss of COD to form the facial isomer of Ir(H)₂(PTA)₃Cl. However, the THP made both meridional and facial isomers of Ir(H)₂(THP)₃Cl upon hydrogenation. The facial was determined to be the kinetically favored product while the meridional was the thermodynamically favored product. The complexes Ir(COD)(DMPE)Cl, Ir(COD)(DEPE)Cl, and Ir(H)₂(PTA)₃Cl were determined to be excellent aqueous hydrogenation catalysts. They catalyzed the reduction allyl alcohol to n-propanol under relative mild conditions. / Master of Science

Architecture is a discipline which requires the recognition of its cyclic pattern of learning where a young architect must have the competence and confidence to make. While he also must be prepared to look at the results critically and to start the cycle over at the beginning, with confidence and joy in the understanding of the process. This project is an attempt to take a section across one of these cycles in the life of an architect. The project explores a set of questions ranging from pure theory about meaning in architecture, to the understanding of site and place, to ideas about the possibility of the use of the tectonic as a critical language for architecture. / Master of Architecture

Demand for emergency food at food pantries nationwide has increased rapidly during the past 15 years. Food pantries have varied policies for distributing food to clients. Clients of a food pantry in Fairfax, Virginia, were surveyed to determine their satisfaction with the food they received and to help develop guidelines in order to improve future food deliveries. Thirty-six food deliveries were made during a 6-week study period. The population studied consisted of 79 children (under age 19) and 41 adults. Children were present in 89% of the households; of these, 77% were headed by single women and 6%, by single men. Eighty-eight percent were satisfied with the foods they received. Clients wished they had received more meat, fresh milk, cheese, eggs, and pasta. Powdered milk was the only food received that was reported as disliked by more than one family. When foods delivered were compared with foods used, clients used less powdered milk, dry beans, and peanut butter than they received, but more fresh milk, meat, cheese, eggs, and fresh vegetables and fruits than were delivered by the pantry driver. Recommended guidelines for types and amounts of foods were developed using basic nutrition principles, as described in the USDA food guide pyramid, modified to fit the types of foods that are available in food pantries and the preferences of those sampled. / Master of Science

The effects of faking on the predictive ability of the CPI and social desirability (SD) scale were assessed. Three hundred and twenty-two subjects were asked to respond to the CPI and the SD scale twice, once responding honestly, and once faking to create socially desirable self-images. Results indicate that subjects could successfully distort their responses on all scales. Depending on the scale characteristics, faking could both reduce as well as increase scale variability and reliability. People who are highly intelligent did not distort their responses any better than people of lower intelligence. Furthermore, response distortion was found to have negative effects on valid scales. It did not affect scales that had no predictive ability. However, for certain scales, faking could improve the likelihood of those scales to predict performance when the amount of faked responses in the sample was between 10% and 30%. Implications for organizations and for further research were also discussed. / Master of Science