Master of Science, The Ohio State University, 2020, Welding Engineering

Aluminum gas metal arc welding (GMAW) uses inert shielding gas to minimize weld pool oxidation and reduce susceptibility to porosity and lack of fusion defects. For aluminum shipbuilding, Naval requirements highly recommend the use of helium – argon mixtures or 100% (pure) helium shielding gas to provide a broader heat field and ensure proper weld fusion, particularly at the weld toes. Pure argon shielding gas can be used but it has proven to be susceptible to lack of fusion and porosity defects, particularly in thick sections that pose a large heat sink where argon's lower thermal conductivity promotes a narrower arc heat field and poorer weld penetration. The continued use of helium is a concern because it's a finite resource that costs approximately 5 times argon. In this study, the rotating electrode pulsed gas metal arc welding (REP-GMAW) process was investigated as a way to solve the argon shielding fusion problem, mitigate helium consumption, and provide shipbuilding cost savings. The target application was horizontal and vertical erection butt joints made from 5083 aluminum plate. An advanced REP-GMAW torch was used that permitted the evaluation of a range of electrode spin diameters and frequencies. Compared to torch weaving at a couple hertz, the arc heat field and bead shape can be more effectively changed since the rotation speeds can be up to 5,000 rotations per minute (~83 hertz). A series of bead on plate tests were used to evaluate the relationship between ER5183 electrode rotation parameters and arc power on constant deposit area bead shape. These tests were compared to stringer beads (no oscillation) that were made with argon, helium, and helium-argon shielding gases. Preferred rotating electrode parameter relationships were developed with pure argon for producing weld beads that had underbead fusion profiles that were equivalent to helium-based weld deposits. For preferred deposit sizes for groove welding, preferred bead shape welds were (open full item for complete abstract)

Committee: Dennis Harwig Dr. (Advisor); Boyd Panton Dr. (Committee Member) Subjects: Engineering

MS, University of Cincinnati, 2002, Medicine : Environmental Health Sciences

Purpose. The purpose of this research was to determine the practicality of using airborne lead measurements obtained with field portable x-ray fluorescence (XRF) technology to manage worker protection programs. The NITON® XL-700 Series XRF was used to measure airborne lead samples from the U.S. Coast Guard Barque EAGLE while undergoing repairs at the Coast Guard Shipyard. Lead-based paint was used extensively during construction of EAGLE, which was completed in 1936 in Hamburg, Germany. Methods: 47 airborne lead samples were collected in 37 mm cassettes on mixed cellulose ester filters over two weeks. Twenty (20) personal and twenty-seven (27) area samples were obtained. Samples collected during week one were analyzed by XRF the following Sunday, when no work was scheduled on EAGLE. Samples obtained during week two were analyzed daily with field portable XRF. The samples were analyzed using NIOSH Method 7702, Lead by Field Portable XRF to determine lead mass. Using known air volume and lead mass, airborne lead concentration was calculated. To verify instrument performance, the samples were later analyzed by NIOSH Method 7082, Lead by Flame AAS. Results: The range of airborne lead concentrations was 8 to 939 μg/m 3 . With daily monitoring by field portable XRF, airborne lead concentration was reduced 77 percent from week one to week two. The average concentration was 176.9 μg/m 3 during the first week, while the average was 41.3 μg/m 3 during the second. With the exposure data gathered in near real-time, workers reduced concentration by implementing controls including vacuum equipped tools and improved ventilation. On twelve (12) occasions during week one, workers engaged in jobs that produced airborne lead concentrations that exceeded the action level. During week two, when daily monitoring by field portable XRF was instituted, workers exceeded the action level six (6) times. Conclusions: Provided that a sheltered workspace with minimal distractions is available to (open full item for complete abstract)

Committee: Dr. C. Scott Clark (Advisor) Subjects:

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2013, History

The San Francisco Bay Area played a critical role in supporting military activities throughout the twentieth century. Due to its location, the Bay Area served as one of the key military staging grounds for the Pacific campaign of WWII, the Korean War, and the Vietnam War. The region benefited from war-related industry, housing the largest shipyard west of the Mississippi and supporting the burgeoning postwar military industrial complex. Its demographics diversified dramatically as soldiers, Vietnam War refugees, and war workers migrated to the region. As part of the Sunbelt, the Bay Area benefited economically from generous military procurement spending. However, over the course of the 1980s, 1990s, and the 2000s, the Bay Area shifted away from having a significant military presence to having practically none. Compared to the approximately thirty military facilities operating in 1980, today all but a handful are either closed or slated for closure. Residents, experts, and scholars wondered how could a single region in the Sun Belt, which benefited from significant federal defense investment, lose so much, so quickly? Many locals blamed the region's "liberal" people and politicians for inciting the military's wrath. Hence, a popular social narrative evolved. Many contended that the navy and Department of Defense deliberately targeted bases in the Bay Area for closure as a way of punishing the Bay Area for its anti-war intransigence. This dissertation challenges the narrative that the Bay Area was punished. It examines the causal factors that led to the elimination of the region's bases. Through three case studies covering base closures in three Bay Area cities, Alameda (Alameda Naval Air Station), Vallejo (Mare Island Naval Shipyard), and Oakland (Oakland Army Base and Fleet and Industrial Supply Center Oakland), a different explanation for the closures emerges. This project demonstrates that the passage of federal policies and legislation, urban encroachme (open full item for complete abstract)

Committee: Stephen Ortiz Ph.D. (Advisor); Douglas Forsyth Ph.D. (Committee Member); Gary Hess Ph.D. (Committee Member); Amy Robinson Ph.D. (Committee Member) Subjects: History