This paper presents the results of testing to determine the appropriateness of the seismic load duration factor and to investigate the possible effect of previous load history from cyclic loading on connection reserve capacity and ductility. The single shear nail and bolt connection types tested represent common connection geometries used in wood construction in the United States. The results of two methods of fully reversing cyclic loading of connections are presented. The first method was a load-controlled test with the applied cyclic loads acting at specified percentages above current nominal design values. The sets of specimens were then ramped to failure and the results were compared to a monotonic control set of specimens to determine if any reduction in connection capacity or ductility had occurred as a result of the cyclic loading. From the load-controlled cyclic testing, it was found that previous cyclic loading at load levels as high as twice current nominal design loads did not adversely affect connection capacity. The second cyclic loading method was a displacement-controlled test that involved successive phases at increasing displacement levels. Each phase consisted of a peak displacement, followed by a series of three decay cycles, then by a series of three cycles at the original peak displacement, the third of which is used to determine the stabilized system. The process is repeated at increasing incremental levels of displacement. The phased displacement stabilized load-displacement curve was fit to an equivalent energy elastic-plastic system for determination of connection parameters. Results from the two cyclic test methods, and from monotonic testing, indicate that the current load duration factor for wind and seismic loading is justified. / Master of Science / incomplete_metadata

The objective of this study was to evaluate various multi-stage circuit arrangements that may be used to improve the column flotation of micronized coal. Laboratory flotation tests were performed with two different samples of Pittsburgh No. 8 seam coal. The first coal, Coal A, was ground to two different particle sizes and subjected to both column and conventional flotation. These tests were performed to obtain an initial understanding of the operational behavior of the column process and to compare the results with those of conventional flotation. The second coal, Coal B, was used in the actual testing of three different column circuit arrangements. The experimental test results were compared to simulated results obtained using a rate-based flotation model constructed in the present work. Several hypothetical flotation circuits were also examined using the simulation model and experimental flotation rate data. The circuit test results showed that each of the different circuit configurations possessed specific advantages in terms of throughput capacity, combustible recovery, ash rejection and sulfur rejection. However, the overall performance curves for each circuit were all found to fall on or just below the maximum separation curve predicted using the release analysis technique. Also, the simulated results in almost all cases predicted better results than what was actually obtained. This discrepancy was attributed to the inability of the rate-based model to adequately describe restrictions associated with the carrying capacity of the column froth. / Master of Science

Not available until OCRd / Master of Science

The purpose of this study was to discriminate between adolescent contraceptive users and nonusers on the basis of five variables; sexual self-concept, family life education, father communication, mother communication, and years of fathers' education. Included in the sample were 116 college freshmen men and women. The results revealed four out of the five variables were able to predict group membership. Adolescent contraceptive users had scores indicating higher sexual self-concepts and more open communication with their fathers, while noncontraceptive users had more months of family life education and had more open communication with their mothers. / Master of Science

This thesis explores the possibility of using mechanical control in the design of a complex end effector. A design methodology is developed and demonstrated. The main goal of this methodology is to maximize reversible steps to direct the design. By attempting to obtain as much mechanical control as possible, several mechanisms are developed which could be used in applications where control of multiple operations by one motor is desired. Along with the demonstration of the design methodology with an end effector design, the application of this methodology to cigarette packaging machines is discussed. / Master of Science

This thesis describes the implementation of a system that can generate two types of image pyramids: the Gaussian pyramid and the Laplacian pyramid. These have been developed using the SPLASH II attached processor, which is a reconfigurable platform based on Field Programmable Gate Arrays (FPGA). The design was first modeled in VHDL, and was then simulated and synthesized to a gate list using a SPLASH II simulator and the Synopsys synthesis tool. The gate list was then mapped onto Xilinx XC4010 FPGA architectures. Three complete designs have been developed to generate pyramids on SPLASH II: two for generating the Gaussian pyramid, and one for generating the Laplacian pyramid. One of the designs produces a complete image pyramid within one image frame time of 33 ms. The other two designs produce complete pyramids within two frame times. All three designs can be used as pipeline stages within a larger image processing system. / Master of Science

Single-mode optical fiber has been widely used not only in long-haul, high speed digital communication systems but also in sensing applications because of its inherent immunity to electromagnetic interference, low transmission loss, wide bandwidth, small size, and light weight. Birefringence is an important parameter of the optical fiber, determining bandwidth in fiber optic telecommunications, and resolution in fiber optic sensors. This thesis describes and demonstrates permanent photo-induced rotation of the principal axes of birefringence in Ge-doped circular-core low-birefringence single-mode optical fiber. Light from a linearly polarized Ar⁺ laser at a wavelength of 488 nm was launched into the fiber along one of the principal axes of the initial birefringence in the fiber. Rotation of the principal axes was observed after several hours of exposure. This observation helps one to understand the mechanism of the photo-induced effects in Ge-doped optical fiber, and to discover possible ways to control the birefringence in the fiber by means of photo exposure. / Master of Science

The urban-rural fringe in the United States is constantly shifting outward from the center of the metropolis, and urban landuses are displacing agriculture. Geographer John Fraser Hart developed the Perimetropolitan Bow Wave model to examine the movement of agriculture in a fifty mile radius of New York City. He concluded that agricultural activities differ in their rates of movement through four identified zones around the urban center. This thesis presents case studies of the movement of agricultural activities around two cities of different size--Washington, D.C. and Richmond, Virginia--to examine the validity of the bow wave phenomenon. The findings of this research are that Hart's model is useful only partially when examining other cities and that individual size and characteristics of the urban area must also be considered when analyzing agricultural change. / Master of Science

A damage identification method incorporating the use of inductive learning is presented. Inductive learning is the process of learning from examples. The method utilizes as much dynamic-response data as is available, ordering this information to find the best data with which to discriminate among a set of damage states available for dynamic testing. This method takes into account the inherent variabilities in the damage identification problem. These inherent variabilities include but are not restricted to sensor noise, changes in environmental conditions, slight changes in boundary conditions, and manufacturing differences. The method statistically isolates changes in the dynamic-response characteristics due to damage from these inherent variances. This method is model-independent and can be used to accommodate any sensors, actuators, and data type. In order to demonstrate the method, an experiment was performed on a 12” x 12” x ⅛” aluminum plate hung horizontally from the corners to simulate free-free boundary conditions. The plate was sensed and actuated by two piezoelectric patches mounted diagonally symmetric from one another. A small test mass (2% of the mass of the plate) was placed at four discrete locations, changing the physical properties of the structure. The structural impedance-responses were measured for all of the damage cases for both sensors. This information was processed by the damage identification algorithm to generate rules to which a small amount of data, extracted from a single set of structural impedance-response information, can be applied. The method was able to successfully discriminate all of the damage states from one another as well as to detect the existence of a change in physical properties due to a damaged state of which there was no prior knowledge. / Master of Science

Mosquito pathogenic strains of Bacillus sphaericus are indistinguishable from nonpathogenic strains based on simple phenotypic tests. DNA-DNA hybridizations performed in 1980 placed the 7 pathogens included in that study in a distinct homology group separate from 5 groups of nonpathogens. The overall homology of the pathogenic strains to the species type strain was only 19% indicating that these pathogens should be a separate species. Since the DNA homology study was published in 1980, many more pathogenic strains have been isolated worldwide. Pathogenic strains have been differentiated from other strains of B. sphaericus by rRNA sequencing, fatty acid analysis, and isozyme analysis. The pathogens have been further classified by type of toxin produced, serotyping, and phage typing. I have used random amplified polymorphic DNA (RAPD) fingerprinting to determine the phenetic relationships among 31 pathogenic and 14 nonpathogenic strains of B. sphaericus. DNA Bands in agarose gel migrating the same distance were verified as being homologous using PCR-generated probes made from the RAPD bands. Band patterns resulting from 8 10-mer primers were examined by three coefficients, Jaccard, Dice, and simple matching. Each coefficient was able to distinguish DNA homology groups, although the relative similarity values differed. In agreement with DNA homology studies, pathogenic strains showed less than 10% similarity to nonpathogens using Jaccard and Dice coefficients. This value was 68% based on the simple matching coefficient. Individual serotypes were clearly indicated among the pathogenic strains by each coefficient. This suggests an overall genetic homogeneity among strains within serotypes. It also parallels the uniform toxicity pattern found within each serotype (unlike the toxin diversity found within B. thuringiensis serotypes). These results together with DNA homology data support the establishment of a new species for the pathogenic strains. / Master of Science