The barrel life of a solid armature rail gun is a critical issue. Arcing along the barrel pathway at the interfaces between the armature and the rails produces severe damage. The ability to protect the rails and yet provide sufficient electrical contact to sustain arc-free high-current flow is desirable. This thesis investigates the use of liquid metal as an interface material between the sliding electrical contact surfaces of the armature and the barrel rails. Experiments were conducted with the Naval Postgraduate Schoolαs 4-inch Rail Gun and liquid metal interface coatings were applied to the armatures. Results indicated that the liquid interface protects the rails and projectile surfaces for static electrical contact. Apparatus has been design to investigate sliding electrical contact between armature and rails in a controlled manner. New rails with a novel Adamy-Maier grooved rail design were fabricated to facilitate coating rails. Various groove patterns have been designed to control the current flow through the rails and across the interface surfaces, while maintaining lateral stability and interface integrity. These experiments are still in progress at the time of this writing. / US Navy (USN) author

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 49-50).

Thesis (M.S. in Applied Physics) Naval Postgraduate School, December2001. / Thesis Advisor(s): Maier, II, William B. "December 2001." Includes bibliographical references (p. 25-29). Also available online.

Thesis (M. Soc. Sc.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 57-61).

Thesis (M.Soc.Sc.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 57-61) Also available in print.

Very few studies have explored the relationship between the availability of certain types of firearms and gun density on both gun aggravated assaults and gun homicides. Nonetheless, research by Koper (2001) discovered that the availability of more lethal types of firearms, not gun density, was directly related to an increase in gun homicide rates for Dallas. However, this study did not take into account certain social and economic variables that may strengthen or weaken the determined relationship. The current study uses data previously analyzed by Koper (2001) and includes social and economic variables that have been linked to lethal violence while using gun aggravated assaults and gun homicides as the dependent variables. The results will help ascertain to what extent the impact of firearm availability on gun crimes is contingent on contextual factors.

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Gun-drilling is one of the highly efficient tools for deep-hole making. The drilled hole possesses good size, positioning, roughness, roundness, and straightness. When the deep-hole is drilled, it is easy to cause wear at the tool-chip and tool-work interfaces at the serious condition so that the gun-drill is subjected to larger feed force. If the feed force exceeds the critical load, then the cutting edge of the gun-drill is broken. However, nowadays the device to measure the feed force in the gun-drill press is not available. This study develops a gun-drill press which possesses two new functions as follow: (1) to measure and to record the feed force during the drilling process;¡]2¡^to return the gun-drill when the feed force exceeds a set value. These two functions can be used to detect the serious breakage of the gun-drill. According to the practice drilling test, the performance of this press can be obtained. Results show that the feed force can be measured using different feed speeds. The gun-drill can stop and return to its origin position when the feed force exceeds the set value. Hence, the performance test of this new machine meets the above-mentioned functions. Using this press, the relationship between the feed force and the wear of cutting edge is investigated at the same feed speed. Results show that wear occurs on the cutting edge of the gun-drill, and the wear area increases with increasing drilling time so that the feed force is also increased. The wear grows from the outer side of the cutting edge to the inner side.