A prototype computer software was created to predict airport hourly capacities and delays~ taxiway hourly capacity, gate group hourly capacity, overall airport hourly capacity, and annual service volumes. The possibility to replace the existing Federal Aviation Administration Advisory Circular 15015060-5 in the future was also explored. The development of the computer software, ICAD--Integrated Airport Capacity and Delay Model was based primarily upon HyperCard as well as other supporting statistical and drafting computer software such as CA Cricket Graph III, Minitab 7.0, MacPaint and MacDraw II 1.1. A friendly user interfaces and internal computations were the two main concerns for ICAD development. In a. typical application interface, runway use configuration is identified from various diagrams. Input parameter are inserted in the model and outputs are readily obtained in table and graphical form. ICAD scripts have been developed i~ HyperTalk, the language associated with HyperCard. Regression equations were used to convert graphs from the FAA AC 15015060-5 into equations in ICAD. This thesis presents descriptions and validations of the prototype model. Conclusions and recommendations are also included. / Master of Science

This study attempts to evaluate whether or not the theories of social change and conflict formulated in the United States and Western Europe can be applied to postcommunist societies. In particular, with Poland as a case study, the applicability of two theories has been examined. One is Ronald Inglehart's theory of a shift from materialist to postmaterialist values in postindustrial societies. The other one is Ralf Dahrendorf's theory of the modern social conflict and the emergence of the underclass in postindustrial societies. The operationalization of Inglehart's theory has been based on the support given to political parties in the Polish parliamentary elections on September 19, 1993. The findings suggest that there is a value cleavage in Polish society between older and younger age cohorts. The conditions of the socioeconomic environment prevailing during the maturation period of each age cohort appear to be a main factor causing the differences in value orientation. Since older age cohorts experienced World War II and the subsequent economic hardships they give priority to personal safety and economic security (materialist values). Younger age cohorts take their economic well-being for granted and are interested in problems like the condition of the natural environment or the sense of life (postmaterialist values). The operationalization of Dahrendorf's theory has been based on statistical data from Poland. The findings suggest that although it is too early to talk about the existence of the underclass in Poland there are social and economic processes which may cause its emergence. These processes include the political and economic diversification of the working class, increasing unemployment, and exclusion of the economically disadvantaged groups of Polish society from the democratic political process. / Master of Arts

Cranes are an indispensable aid to the construction industry, and much responsibility with regard to performance has been placed in the hands of the operator. The problem of controlling sway of the load due to crane motion, or wind effects must be solved dynamically by the operator to increase productivity and maintain safety. At the hands of inexperienced operators safety is sometimes sacrificed in order to expedite the required task. In an effort to minimize the loss of life and equipment, and to maximize productivity a system for actively damping the crane load has been developed. This paper discusses an active damping system using state feedback control for a crane load modeled as a two-dimensional pendulum. Mathematical analysis indicates that the control theory used to damp the sway in the pendulum may be extended linearly into three dimensions. Thus, two control algorithms, operating independently, can be used to damp sway in two horizontal dimensions. The designed system responds to sensed displacements of the load from equilibrium. It employs a control arm positioned a small distance below the boom tip that applies a force to the cable to damp the sway of the load. This system is intended to allow less experienced operators to work more efficiently and safely, decreasing training time and increasing overall productivity. / Master of Science

High-performance polymeric composites are currently being considered as state-of-the-art material systems for future supersonic aircraft and space structures. However, the long-term durability and environmental stability of these materials continue to be under question. Continued application of these composites in aerospace structures is contingent upon the long-term durability of these material systems. Polymeric materials have been known to undergo both physical as well as chemical aging. The aging time, temperature, and environment play a significant role in affecting the physical and chemical aging behavior in the polymers. Currently, there is a dearth of information on the combined effects of physical and chemical aging in polymer-based composites. This study describes the effect of sub-T_g environmental aging on the mechanical properties of two high-performance polymeric composite systems. The effect of chemical degradation on the durability of the material systems is discussed. Further, the effect of environmental stress cracking (ESC) behavior of high-performance composite materials in the presence of organic solvents is investigated and the implications of ESC on durability are studied. Also included in this thesis is a study of the physical aging characteristics of the composites, via measurement of the viscoelastic (creep) properties. Accelerated characterization techniques were employed to predict long-term physical aging behavior. Fiberite 954-2 (a thermoplastic toughened cyanate ester resin) and its graphite-reinforced composites, and Fiberite ITX (a semicrystalline thermoplastic resin) and its graphite fiber-reinforced composites (IM8/ITX) were used in the study. These material systems were under consideration for usage in high-speed civil transport (HSCT) aircraft. This aircraft is expected to have an operating temperature of around 150°C (based on a 2.4 Mach number), an operating pressure at service altitude of 2 psi (0.136 atm), and a flight life in the excess of 60,000 hours at the above-mentioned conditions. The aging of the specimens was carried out for periods of up to 9 months at temperatures between 140°C to 200°C in three different environments; an inert nitrogen environment, an environment with a reduced air pressure of 2 psi (0.136 atm), and ambient atmospheric air. The results from stress-strain, flexure, and micro-indentation tests indicated a substantial reduction in material properties with aging in the different environments. The bending strength, strain to failure, and hardness values of the two composite systems decreased by as much as 20-50%. Tensile modulus on the other hand showed an increase of 20% after 6 months of aging in air, indicating apparent embrittlement with aging. Chemical degradation/damage was also monitored by penetrant enhanced x- radiography, scanning electron microscopy (SEM), and scanning acoustic microscopy (SAM). The chemical aging/degradation was seen to be sensitive to the oxygen partial pressure in the aging environment. The greater the amount of oxygen in the aging environment, the more the loss in the material properties. The glass transition temperatures (T​​_g) of the two material systems were sensitive to both the aging environment and aging time. The T_g of both systems increased over long aging times as seen from dynamic mechanical analysis (DMA) measurements. However, increased oxygen concentrations appear to reduce the T_g. Changes in the T_g of both material systems were a complex behavior attributable to the varying oxygen concentrations in the aging environments, and the combined occurrence of physical aging, degradation, etc. in the materials. The chemical degradation in the composites appears to be via an oxidation mechanism and the micro-indentation results further indicate diffusion-controlled oxidation. Weight changes of samples (neat resin and composites) were also monitored over the entire period of the study and these showed a sensitivity to the oxygen concentration in the aging environment. The greater the oxygen in the environment, the greater the weight loss in the specimens, indicating an oxidation phenomenon. DMA and tensile creep were performed to study the interaction of creep and physical aging in these material systems. Long-term creep predictions of the composites were made using Time-Temperature Superposition (TTSP) and Effective Time Theory (ETT) techniques. The IM8/954-2 composites behaved in an anomalous fashion at times. This may be attributable to the blended nature of the 954-2 resin system, possible post-curing and phase separation of the resin, and thermal decomposition at elevated temperatures. The solvent testing of composites based on thermoplastic polymers revealed susceptibility to ESC. Bending strength losses up to 30% were seen from flexure tests on unidirectional composites. It was also seen that residual stresses in cross-ply laminates were sufficient to trigger ESC after exposure to common organic solvents for an hour. The damage/failure modes were captured by SEM micrographs. / Master of Science

This research develops a set of predictive measures enabling software testers and designers to identify and target potential problem areas for additional and/or enhanced testing. Predictions are available as early in the design process as requirements allocation and as late as code walk-throughs. These predictions are based on characteristics of the design artifacts prior to coding. Prediction equations are formed at established points in the software development process called milestones. Four areas of predictive measurement are examined at each design milestone for candidate predictive metrics. These areas are: internal complexity, information flow, defect categorization, and the change in design. Prediction equations are created from the set of candidate predictive metrics at each milestone. The most promising of the prediction equations are selected and evaluated. The single "best" prediction equation is selected at each design milestone. The resulting predictions are promising in terms of ranking areas of the software design by the number of predicted defects. Predictions of the actual number of defects are less accurate. / Master of Science

Drift was measured monthly at four sites on a southern Appalachian stream in order to examine spatial and temporal patterns along elevational and stream size gradients. Measurements consisted of four, one-hour samples corresponding to dawn, mid-day, dusk, and mid-night monthly for 14 months. On average, only 10% of the drifting insects were terrestrial, but terrestrial inputs became numerically important during summer and fall. There were no significant differences among sites in aquatic insect drift density, although taxa richness and total drift (#/sec) increased significantly downstream. None of the sites exhibited a consistent diel pattern. But, all of the lower three sites exhibited decreased drift density during the day. <i>Baetis</i>, the dominant aquatic taxon in the drift, exhibited a typical alterans patterns at UBC, LBC, and CC. Aquatic insect drift density was highest in summer when flows were lowest, while total drift (#/s) was highest in late spring and winter. FPOM and mean daily water temperature accounted for 64% of the variation in total aquatic insect drift density and 60% of <i>Baetis</i> drift density, suggesting both passive and active components in drift. Both variables were also highly correlated with drift density. Taxonomic composition of drift differed from that of the benthos, indicating drift was not simply random, but that taxa vary in the propensity to drift. Overall, this study found more evidence of temporal (diel and seasonal) drift patterns than spatial (along the gradient). / Master of Science

Cranes, which comprise a significant class of material handling equipment, are basically designed to lift and lower loads. In addition to dynamic loading, cranes are exposed to loads which may be environment specific. Many crane accidents are due to uncontrolled swaying of the payload resulting in collisions with construction workers or objects. At present, it is left to the operator to apply his/her skills in controlling this uncontrolled swaying. If the controlling is automated and computer controlled, the effect of human errors and limitations can be minimized. The control of this sway will thus greatly improve safety and significantly enhance productivity. The control strategy in the present thesis is based on applying appropriate, periodic balancing forces and moments to the crane cable to dampen the oscillation. The present thesis presents a discussion on the experimental methods attempted before the development of an automated control. / Master of Science

Assuming that its deformation is both static and homogeneous, a method was devised within the framework of finite strain theory to calculate the elastic constants of a crystal at zero pressure as well as functions of pressure. As this method can be used for a crystal of any symmetry with a variety of potentials, elastic constant calculations were completed for both quartz and cristobalite using the potentials derived by Lasaga and Gibbs (1987, 1988), Tsuneyuki et al. (1988), van Beest et al. (1990) and Boisen and Gibbs (1993). Among the four theoretical potentials derived from force fields calculated for molecule H₆Si₂Q₇, two potentials associated with the SiO bond stretching as well as the OSiO and the SiOSi bond angle bending terms yield reasonable agreements with the experimental data, supporting the assumption that the binding forces in crystals are similar to those in small molecules (Gibbs 1982). Using the semi-empirical potentials, including the SQLOO potential derived with the covalent model (Boisen and Gibbs 1993) and two derived with the ionic model (Tsuneyuki et al. 1988; van Beest et al. 1990), calculations of the elastic constants reproduce the experimental results for both quartz and cristobalite. The pressure derivatives of the elastic constants calculated with these potentials also agree with the experimental results measured for quartz at low pressures and yield pressure derivatives of the bulk modulus that are in close agreement with that observed for quartz. Using the SQLOO potential, although the results of the calculations do not agree with the experimental data as well as those calculated using the two ionic potentials, the agreement of the calculations made with the theoretical potentials was improved significantly. Finally, using the three semi-empirical potentials, the elastic constants were calculated as functions of pressure for quartz and cristobalite up to their transitional pressures. Calculated for both quartz and cristobalite, different behaviors of the elastic constants were found using different potentials. For cristobalite, the variations of its elastic constants and bulk modulus are better modeled by the SQLOO potential as its structural behaviors calculated with the SQLOO potential are consistent with the X-ray diffraction studies. / Master of Science

Controlled cross circulation was performed in six pairs of dogs to assess hemodynamic changes in the donor dog. Cardiopulmonary bypass was performed for 45 minutes, with an aortic cross clamp time of 3 5 minutes. Anesthesia was maintained in the donor dog with 1.8% end-tidal isoflurane. Parameters before and after controlled cross circulation were compared using a Wilcoxon Signed Rank Test. Donor left ventricular dP/dt max, pulmonary capillary wedge pressure, blood volume, systemic vascular resistance, heart rate, total protein, platelet count, and white blood cell count did not change significantly. Donor cardiac output, end diastolic volume, central venous pressure, stroke volume, mean arterial blood pressure, and packed cell volume all decreased significantly (p<O.05). Recipient blood volume and donor cardiac performance (LV dP/dt max/end diastolic volume) increased significantly (p<O.05). / Master of Science

This thesis examined the effects of luminance contrast, raster modulation, and ambient illumination on readability and image quality of text presented on a CRT display. Participants read a Tinker Speed of Reading text passage on the monitor and then responded when they found the out-of-context word in the passage. Correct responses and response times were recorded. Participants also rated the image quality of the monitor by selecting a number between one (worst imaginable) and nine (best imaginable). An ANOVA revealed that luminance contrast significantly affected errors. It is suggested that luminance contrasts of 7:1 be used to maintain low error rates. None of the independent variables affected the time required to read the Tinker passages. However, luminance contrast, raster modulation, and illumination significantly affected the subjective quality ratings. Participants rated the 3:1 luminance contrast, the 1.2 RAR, and the 1000 lux ambient illumination conditions as possessing the lowest image quality. From this research, it can be concluded that 7:1 is the preferred contrast ratio. This conclusion is based upon the findings that the 3:1 and 7:1 luminance contrast conditions produced the fewest errors and the 5:1 and 7:1 luminance contrast conditions produced the highest subjective image quality ratings. This recommendation holds over a RAR range of 0.8 to 1.2 and an ambient illumination range of 10 to 100 lux. High illumination levels would require special attention due to the low image quality ratings for the 7:1/1000 lux interaction. / Master of Science