Predation is a frequently studied subject, but estimating crushing predation in mollusk communities is challenging. Shells record successful attacks, but it is not always possible to identify attacks on an individual basis. Repair scar frequency is a common proxy for crushing mortality, but shell repair does not directly measure mortality, so results are ambiguous. Borrowing a technique from Vermeij (1982), crushing mortality frequencies were estimated in a recent shell assemblage. Because crushing damage can be confused with taphonomy, a taphonomic baseline was established: the cause of death of drilled shells is known, so additional damage is postmortem. The frequencies of several damage types were tallied for drilled shells to estimate a taphonomic baseline for the assemblage. The same frequencies were calculated for undrilled shells (cause of death unknown). In many cases, undrilled shells had significantly higher frequencies than drilled shells. The differences in damage frequencies likely are caused by crushing predation.

The study of coning in oil production is important because of huge water production associated with oil production around the world each year. Estimation of critical coning rate has been the subject of numerous studies and a number of correlations have been reported. This study presents a review of the current available methods for estimating critical coning rate for both vertical and horizontal wells. The various methods and correlations are compared and the assumptions on which they are based evaluated. Following comparison made between the correlations, the most reliable theories are identified for both vertical and horizontal wells separately. Among the correlations for vertical wells, this study recommends two implicit methods presented by Wheatley and Azar Nejad et al. They determined the oil potential distribution influenced by water cone with a remarkable accuracy. For horizontal wells, two methods, Joshi???s equation and Rechem et al formula, are considered to be the most reliable. Joshi???s equation provides lower estimates than Chaperon???s correlation in which the water cone effect on oil potential was neglected. The Recham et al formula also gives a similar result. On the whole, the Rechem et al method is preferred.

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Drilling is one of the most commonly used material removal processes for producing holes in the manufacturing industry. Despite the long history of design and developments of hole making tools, the modern twist drill, which undertakes most of the hole making tasks, is largely based on Morse’s geometrical design patented in 1863. however, considerable improvements in the technological performance of drilling operations as assessed by the forces, power, drill-life and hole quality have been achieved through the use of stronger and more wear resistant tool materials, better selection of the salient drill point features and improvements in drill manufacturing methods involving increased automation and geometrical control of drill variability. A variety of drill point modifications and designs have also been proposed and made commercially available although the modern conventional general purpose twist drill design still remains the standard product of drill manufacturers commonly available in stock. The improvement of the technological performance of twist drills has traditionally been the domain of the drill manufacturers who provide technical information and advice often in the form of machining feed and speed recommendations for use in practice. Such machining recommendations or data may also be found in special handbooks which sometimes include drilling performance data such as thrust, torque and power requirements or the expected drill-life in the form of tables, monographs or empirical equations which include the obvious process variables such as the feed and speed. (For complete introduction open document)

Thesis (Ph.D.)--University of Tulsa, 1995. / Bibliography: leaves 77-81.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains viii, 44 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 40-43).