The digitalizedradiographical system provides a set of radiographic projections from predetermined angles of view. From these finite set of digitizedradiographs, the internal structure of the body at any arbitary sa...
详细信息
The digitalizedradiographical system provides a set of radiographic projections from predetermined angles of view. From these finite set of digitizedradiographs, the internal structure of the body at any arbitary sagital slice can be reproduced using Tomosynthetic technique. However, the resulting image quality is degraded by superimpositions of the structures outside of a focused slice. This paper proposes a new reconstruction method fordigital tomo-synthesis to reduce the undesired superimposition. It utilizes a 3-dimensional convolution process with the inverse filter function, which is computed according to the point spread function determined by the projection geometry. By the computer simulation, the advantages of the algorithm have been examined.
Air cushion vehicles (ACVs) have operated successfully on commercial routes for about twenty years. The routes are normally quite short; the craft are equipped with radar andradio navigation aids and maintain continu...
详细信息
Air cushion vehicles (ACVs) have operated successfully on commercial routes for about twenty years. The routes are normally quite short; the craft are equipped with radar andradio navigation aids and maintain continuous contact with their terminals. Navigation of these craft, therefore, does not present any unusual difficulty. The introduction of air cushion vehicles into military service, however, can present a very different picture, especially when external navigation aids are not available and the craft must navigate by deadreckoning. This paper considers the problems involved when navigating a high-speed air cushion vehicle by deadreckoning in conditions of poor visibility. A method is presented to assess the ACV's navigational capability under these circumstances. A figure of merit is used to determine the sensitivity of factors which affect navigation such as the range of visibility, point-to-point distance, speed, turning radius and accuracy of onboard equipment. The method provides simplistic but adequate answers and can be used effectively to compare the-capability and cost of alternative navigation concepts.
A ship design methodology is presented fordeveloping hull forms that attain improved performance in both seakeeping andresistance. Contrary to traditional practice, the methodology starts with developing a seakeepin...
A ship design methodology is presented fordeveloping hull forms that attain improved performance in both seakeeping andresistance. Contrary to traditional practice, the methodology starts with developing a seakeeping-optimized hull form without making concessions to other performance considerations, such as resistance. The seakeeping-optimized hull is then modified to improve other performance characteristics without degrading the seakeeping. Presented is a point-design example produced by this methodology. Merits of the methodology and the point design are assessed on the basis of theoretical calculations and model experiments. This methodology is an integral part of the Hull Form design System (HFdS) being developed for computer-supported naval ship design. The modularized character of HFdS and its application to hull form development are discussed.
After contrasting the r&d climate of air and sea vehicles to provide the background, several specific inhibitors to innovation in naval ships are made evident through an analysis of some of the history of roll sta...
After contrasting the r&d climate of air and sea vehicles to provide the background, several specific inhibitors to innovation in naval ships are made evident through an analysis of some of the history of roll stabilization. These and other inhibitors recur many times elsewhere, and suggestions are made as to how the underlying cause of these inhibitors might be alleviated by giving attention to various aspects of the r&d environment for innovation in naval ships.
This book systematically clarifies the casing deformation prevention and control technologies based on the integration of research area of both geology andengineering. These technologies incorporate reservoir geomech...
详细信息
ISBN:
(数字)9789819666843
ISBN:
(纸本)9789819666836;9789819666867
This book systematically clarifies the casing deformation prevention and control technologies based on the integration of research area of both geology andengineering. These technologies incorporate reservoir geomechanics, casing deformation mechanics and hydraulic fracturing mechanics. It covers fluid channel-fault activation model and casing deformation mechanisms, types and formation conditions of fluid channels, casing deformation risk prediction technology, casing deformation early warning technology based on microseismic and fracturing treatment curves, casing deformation control technology based on hydraulic fracturing simulation and casing deformation prevention strategy. This book is a valuable reference for both technical personnel and graduate students working in petroleum engineering, rock mechanics andreservoir geomechanics.
暂无评论