Weftless Bead design has long been in existence and still used in many passenger car, bus, truck and agriculture tractors. The ideal bead design is a high strength flexible cable with minimal cross section and covered by rubberized nylon, rayon or steel wire side wall. The basic tire bead designs are weftless bead with rubberized ribbon of parallel wires of multiple wound layers and a continuous wire wound in sufficient number of loops to give the required strength. Weftless bead failures generally occur within about 5cm from the end of the overlapping parallel wire ribbon. The cause for this failure is generally attributed to the mounting process in which the diameter of the tire bead is changed during the mounting process in the well of the rim. A finite element model of the tire bead was developed and under the known stresses of the mounting and final use conditions. The Weftless bead generally consists of five steel wires in parallel in a continuous rubber tape or ribbons, which loosely secures the wires in a soft insulating rubber. The ribbon is wound into a hoop with four courses resulting in a grommet composed of a stack of wires. This ribbon with ten cut ends forming a splice, with five at the inner cut edge and five at the outer cut edge. A continuous bead formed from a single wire does not have this failure prone splice region. Field data and the finite element calculations show the failure point of the weftless bead is almost always at the under lap or at the starting point of the weftless bead. Continuous wire bead have significant advantages in safety over the Weftless bead still used in tires.

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Polymer bead foams are manufactured through a sintering process using foamed polymer beads. It is worth emphasis that the bead foam technology is the only process that can produce 3-dimensionally shaped foam products with ultra-low densities. This unique feature of bead foam process has been attracting enormous attentions from various foam industries. However the conventional bead foam processes still have some limitations associated with manufacturing productivity and safety during the treatment. This thesis deals with novel approaches to innovative and cost-effective manufacturing processes for polystyrene (PS) and polypropylene (PP) bead foam materials, based on thorough understanding of the scientific issues in bead foam technologies. This study also demonstrates the feasibility of new processes by conducting a series of foaming experiments such as batch foaming and continuous extrusion foaming as well as steam chest molding which is a critical common process for all bead foam products. In addition, this study aimed at developing new bead foam processes based on the relationship between the cellular structure and processing/material parameters. When it comes to expandable PS (EPS) bead process, research efforts have been made to eliminate n-pentane which has some disadvantages related to its flammability and low boiling temperature. In addition, the bi-celullar PS foams that feature the superior thermal-insulation property was manufactured through continuous extrusion foaming process. With regard to expanded PP (EPP) bead process, research efforts were focused on the development of cost-effective continuous foaming process in order to resolve the high cost issue of conventional EPP beads. These research strategies were designed on the basis of the comprehension of thermoplastic foaming, steam chest molding process and gas dissolution/diffusion phenomena. The results in the thesis provided considerable introductory and advanced knowledge about the bead foam technologies so that further promising researches can be performed to invent entirely new bead foam materials such as ultrahigh–temperature-durable bead foam products, biodegradable bead foams, other highly functional bead foam products aside from EPS and EPP bead foams.

Polymer bead foams are manufactured through a sintering process using foamed polymer beads. It is worth emphasis that the bead foam technology is the only process that can produce 3-dimensionally shaped foam products with ultra-low densities. This unique feature of bead foam process has been attracting enormous attentions from various foam industries. However the conventional bead foam processes still have some limitations associated with manufacturing productivity and safety during the treatment. This thesis deals with novel approaches to innovative and cost-effective manufacturing processes for polystyrene (PS) and polypropylene (PP) bead foam materials, based on thorough understanding of the scientific issues in bead foam technologies. This study also demonstrates the feasibility of new processes by conducting a series of foaming experiments such as batch foaming and continuous extrusion foaming as well as steam chest molding which is a critical common process for all bead foam products. In addition, this study aimed at developing new bead foam processes based on the relationship between the cellular structure and processing/material parameters. When it comes to expandable PS (EPS) bead process, research efforts have been made to eliminate n-pentane which has some disadvantages related to its flammability and low boiling temperature. In addition, the bi-celullar PS foams that feature the superior thermal-insulation property was manufactured through continuous extrusion foaming process. With regard to expanded PP (EPP) bead process, research efforts were focused on the development of cost-effective continuous foaming process in order to resolve the high cost issue of conventional EPP beads. These research strategies were designed on the basis of the comprehension of thermoplastic foaming, steam chest molding process and gas dissolution/diffusion phenomena. The results in the thesis provided considerable introductory and advanced knowledge about the bead foam technologies so that further promising researches can be performed to invent entirely new bead foam materials such as ultrahigh–temperature-durable bead foam products, biodegradable bead foams, other highly functional bead foam products aside from EPS and EPP bead foams.

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Master of Science / Department of Diagnostic Medicine/Pathobiology / Melinda J. Wilkerson / Tick-borne bacteria, Ehrlichia canis, Anaplasma platys, and Ehrlichia chaffeensis are significant zoonotic pathogens of dogs and humans worldwide. In tropical regions such as Grenada, West Indies, dogs represent a major reservoir for E. canis and A. platys, and they are often co-infected. The purpose of this study was to develop a serologic, multiplex bead-based assay to detect species-specific exposures to E. canis, A. platys, and E. chaffeensis in dogs for purposes of surveillance and public health. Peptides from specific outer membrane proteins of P30 for E. canis, OMP1X of A. platys, and P28-19/P28-14 of E. chaffeensis were coupled to magnetic beads and assays were optimized using the multiplex Luminex xMAP® platform. In experimentally infected dogs, the multiplex assay successfully detected antibodies for E. canis and E. chaffeensis, but not A. platys. In the Grenadian population (n=104), the multiplex assay and the in-house ELISA, the SNAP® 4Dx®, detected A. platys antibodies as well as Ehrlichia spp.. Multiplex assay results were found to have “good” and “very good” agreement with the ELISA and IFA for E. canis antibody-positive dogs (K value of 0.73 and 0.84 respectively), while ELISA and IFA had “very good” agreement with each other (K value of 0.85). A. platys multiplex results had only “poor” agreement with ELISA and IFA (K value of -0.02 and 0.01, respectively), while the ELISA and IFA tests had “moderate” agreement with each other (K value of 0.5). These tests showed the prevalence of exposure to E. canis to be comparable with previous studies (38% in 2014), but a doubling of exposure to A. platys determined by IFA and 4Dx® from 9% in 2006, to 20% in 2014. Bayesian modeling (performed on E. canis data only) suggested conditional independence between the IFA, 4Dx®, and MAG tests using consensus priors calculated from literature, and that the bead-assay had comparable sensitivity and specificity to the IFA and ELISA tests. In conclusion, the multiplex peptide assay performed well in detecting the seropositive status of dogs to E. canis and had good agreement with commercial assays; however, more work needs to be done to assess performance in populations of dogs with exposures to multiple species of Ehrlichia. Further, the reasons for low seroreactivity to A. platys need to be further investigated.

This study was undertaken with the objective of determining the effect of gap distance on the weld bead geometry and the mechanical properties of the weldments. Low-alloyed and low carbon steel plates were welded under different conditions where each weldment had different gap distance and weld bead grooves. The influences of welding parameters namely, welding speed, current and voltage on the weld bead were examined in terms of weld bead penetration and heat affected zone and weld metal zone hardness variations.

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