Optimization techniques are used to investigate changes in structural design which increase the energy absorbing capabilities of a marine vessel in a collision. The structural model of the vessel includes the stiffened shell, web frame supports, and rigid bulkheads. The failure criterion used is hull rupture, appropriate for tanker design. The collision scenario is a right angle strike by a rigid vertical bow midway between two rigid bulkheads. The stiffened shell is modelled as a series of longitudinal beams in plastic bending and plastic membrane tension. Optimization parameters included both the number and dimensions of the transverse web frames and longitudinal beams. The technique was applied to the redesign of a large oil tanker. Minimizing the weight with a constraint on the energy was superior to maximizing the energy with a weight constraint in both computation time and performance. Optimization increased the volume of the shell beams while decreasing their moment-of-inertia. In addition the volume and strength of the frame were decreased precipitating early development of membrane tension in the shell and spreading of damage throughout the compartment. An reduced the number of web frames from optimum design six to two and increased the energy absorbed before rupture by 130%. Lesser collisions energies were found for more conservative designs which included a set number of web frames and restrictions of other design parameters. The use of high strength steel was also investigated. / M.S.

The possibility that visual thresholds fluctuate in a circadian rhythmic (twenty-four hour) pattern was examined. Subjects were tested at 0400h, 1000h, 1600h and 2200h in a 30 minute dark adaptation procedure using a von Békésy tracking method. Two experiments were performed; the first tested cone functions with a red 1 degree monochromatic test stimulus located ten degrees nasally. There were no sex differences for the ten male and female subjects used in this study. However, there were time of day differences with higher thresholds at 1000h than at any other time. The second experiment examined both rod and cone thresholds with a heterochromatic test stimulus. Sex differences were found 'for the 10 male and 10 female subjects. The rods for males were found to exhibit significantly higher thresholds at 1000h than any other time. There were no significant differences for females. The null results for females may be due to an influence of the menstrual cycle on vision. The rod differences for males is thought to occur because of rod outer segment shedding which also has a circadian rhythm. A circadian rhythm questionnaire was administered to the subjects and it was found that morningness and vigorousness related to visual thresholds. / Master of Science

A higher-order shear deformation theory is used to analyze laminated anisotropic composite plates for deflections, stresses, natural frequencies, and buckling loads. The theory accounts for parabolic distribution of the transverse shear stresses, satisfies the stress-free boundary conditions on the top and bottom planes of the plate, and, as a result, no shear correction coefficients are required. Even though the displacements vary cubically through the thickness, the theory has the same number of dependent unknowns as that of the first-order shear deformation theory of Whitney and Pagano. Exact solutions for cross-ply and anti-symmetric angle-ply laminated plates with all edges simply-supported are presented. A finite element model is also developed to solve the partial differential equations of the theory. The finite element model is validated by comparing the finite element results with the exact solutions. When compared to the classical plate theory and the first-order shear deformation theory, the present theory, in general, predicts deflections, stresses, natural frequencies, and buckling loads closer to those predicted by the three dimensional elasticity theory. / Master of Science

The main purpose of this research is to determine if polymer films can prevent fretting between two metals, and if they can, what the protection mechanisms are. This research is a part of fretting corrosion studies currently funded by the Army Research Office. Four thermoplastic polymers were tested for their effectiveness. Two other independent variables were also tested: plate hardness and plate roughness. A ball-on-plate device was built to approximate point sliding at the fretting corrosion interface. The tribometer has two experimental positions that are electrically insulated from the rest of the apparatus so that an electrical circuit could be used to monitor metal-to-metal contact. All experiments were run with 52100 steel balls, 1040 steel plates, a normal load of 45 N (10 lbf), an amplitude of .33 mm (.013 in.) and a frequency of 20 Hz. PVC films were found to prevent fretting and metallic contact for 40 minutes. An electrochemical fretting corrosion mechanism has been suggested to explain this behavior. PTFE, LDPE, and PSF films could all produce fretting corrosion while preventing metal-to-metal contact for 40 minutes. Plate hardness and plate roughness had no statistical significance on the measured minimum fretting friction force. / M.S.

Basic components of nineteenth century American nationalism influenced the creation of a national library in the United States. Manifest destiny, mission, nativism, and cultural nationalism provided the impetus to build an institution that preserved, symbolized, and spread national thought and ideals. Five major congressional acts made the Library of Congress the national library. The expansion of the Library's rooms in the Capitol (1865), the transfer of the Smithsonian Institution library (1866), purchase of the Peter Force collection of Americana (1867), the copyright law of 1870, and approval of a new library building (1886), made the Library the center of literary deposit, and the cultural, intellectual representative of the United States. / Master of Arts

The effect of date and method of lifting on ethylene production by 1-0 loblolly pine (Pinus taeda L.) seedlings during cold storage, the dose-response relationship between ethylene and loblolly pine seedlings during cold storage, and the effect of water stress on ethylene and aminocyclopropane-1-carboxylic acid (ACC) production in two half-sib loblolly families were investigated. Seedlings stored in Kraft-Polvethvlene (K-P) bags showed a general trend of increasing ethylene concentrations from November through February, with an abrupt drop in March. Production rates may be related to the level of dormancy of the seedlings, with the peak in production corresponding to fulfillment of the chilling requirement. Ethylene concentrations within the K-P bags generally declined over the twelve weeks in cold storage. Roots produced significantly higher levels of ethylene while stored in the K-P bags; however, when incubated under light, the needles produced higher concentrations. Roots of machine-lifted seedlings produced significantly higher levels of ethylene than roots of hand-lifted seedlings. However, rates tended to moderate during storage and differences in production between HL and ML whole seedlings were not significant, which suggests that mechanical lifting is not a source of increased ethylene production. A dose-response study indicated that ethylene fumigation during cold storage tended to slightly enhance growth of outplanted seedlings. The effects of water stress on a Virginia Coastal Plain (CP) and an East Texas Drought Hardy (DH) loblolly family were also investigated. Ethylene production during severe stress (-2.8 MPa) appeared to be related to drought hardiness, with the CP seedlings producing much higher levels. Roots of both families produced greater levels of ethylene than the needles and may be due to an enhanced ability to convert 1-Aminocyclopropane-1-carboxylic acid (ACC) to ethylene. / Master of Science

Insignificant diurnal variations make the reliance on thermal inertia to ameliorate the thermal discomfort in the hot humid region impossible. Natural ventilation, therefore, is not only important, but the velocity of air that gets into the living area is crucial. Various ways of creating negative pressure (a process of increasing the interior air speed) are examined. The performance of roof types with different horizontal openings in enhancing interior air movement was investigated in an open throat wind tunnel. The results indicate a significant difference in the interior air velocity with roof type A opening type 1 (see fig. 27 and fig. 28). The thesis explores other ways of creating climate adapted architecture in providing acceptable comfort level in the hot humid climate. Warm humid climates are defined, and data for one example (Lagos, Nigeria) are analysed. Comfort zones are established relative to the region being investigated and the methods of limiting interior heat gain are described. The effects of orientation, cross ventilation and material choice are discussed. / Master of Architecture

This study investigated the impact of the ECIA Chapter 2 Block Grant program and the extent to which the legislative intent was realized in a sample of eight local education agencies (LEAs) in Virginia. Specifically, three research questions were investigated: Did the implementation of ECIA Chapter 2 affect formerly funded categorical programs in the LEAs?; Did the implementation of ECIA Chapter 2 result in the reduction of administrative costs and paperwork burden for the LEAs?; and, Did the implementation of ECIA Chapter 2 provide increased LEA responsibility for the design and implementation of local education programs? The study included data collection at eight Virginia LEAs, Amelia, Arlington, Charlottesville City, King George, Powhatan, Rappahannock, Richmond City and Suffolk City. Administrative, programmatic and fiscal effects associated with ECIA Chapter 2 implementation for the 1982-83 school year were examined with the aid of a semi-structured interview guide. Data were analyzed through the use of the constant comparative method developed by Glaser and Strauss. Data were analyzed across study sites and in case study format. Study findings indicated that the implementation of ECIA Chapter 2 had a detrimental effect on the local programs previously supported with federal categorical program funds. Seventy-six percent of the local programs in study sites were diminished in some way with the implementation of Chapter 2. New local programs supported with Chapter 2 funds in study sites differed from those supported with categorical funds in significant ways. Second, the study found that three study sites experienced reduced administrative costs and paperwork, one experienced no difference, and one-half of the study sites experienced increased administrative costs and paperwork under Chapter 2. Finally, across all study sites, it was found that the implementation of ECIA Chapter 2 did not result in an increase of LEA involvement in program planning and development activities. / Ed. D.

Biaxial stress fatigue data is carefully examined in order to determine how much foundation exists for a rational approach to classical stress-based fatigue limit analysis involving biaxial stress components. A review is given of the methods presently in vogue, and new methods are suggested for obtaining equivalent mean and equivalent alternating stresses. Some groundwork is laid for the consideration of stress gradient influence on fatigue behavior. There are also some observations concerning the Distortional Energy and Tresca criteria and how they are incorporated in fatigue design procedures. The work is restricted to cases in which the alternating principal stress axes have fixed orientation. / Ph. D.

Recently a variety of national reports have been completed which call for school reform. Additionally, there has been an abundance of research which attempts to identify the characteristics of effective schools. Throughout the literature on school reform and effectiveness, school climate is consistently identified as an important factor in effective schools. However, questions concerning how schools improve their climate and what the effects and obstacles of such efforts are remain unanswered. School climate improvement efforts tend to fall into two major categories which can be referred to as either formal systematic approaches or informal non-systematic approaches. Formal approaches exist where the developer of the approach states specific steps and procedures which are followed by a school to improve its climate. Informal approaches are also being used by schools where the principal and staff identify and implement various actions which are undertaken to improve the school's climate for learning. This study identified and described both a formal and an informal approach to school climate and determined the effects and obstacles encountered with each approach. Two secondary schools using each type of approach were studied and compared. The procedures and activities used by each of the four schools under study were described. The outcomes and obstacles encountered in each school's climate improvement process were identified. The findings of the study were that all four schools in the study had positive outcomes regardless of the approach used. Common obstacles occurred in all four schools. They included lack of staff time to address school concerns, some staff did not support the school's efforts and students and parents were slow to respond positively to the staff's efforts. / Doctor of Education