作者：
GULLIFORd, AHistorian
photographer and doctoral student in the American Culture Ph.D. Program Bowling Green State University. He is the author of America's Country Schools (Washington D.C.: The Preservation Press 1984). His articles and photographs have appeared in The Christian Science Monitor The Chicago Tribune Historic Preservation History News and American Heritage.
A ship design methodology is presented for developing hull forms that attain improved performance in both seakeeping and resistance. Contrary to traditional practice, the methodology starts with developing a seakeepin...
A ship design methodology is presented for developing hull forms that attain improved performance in both seakeeping and resistance. 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.
A turning point occurred in naval engineering in 1972 when the U.S. N avy chose to use marine gas turbines for the propulsion of its new SPRUANCE and PERRY Class ships. This paper reviews the more than twenty years of...
A turning point occurred in naval engineering in 1972 when the U.S. N avy chose to use marine gas turbines for the propulsion of its new SPRUANCE and PERRY Class ships. This paper reviews the more than twenty years of experience with turbine technology and its design integration into combat ships needed to make that decision. It is concluded that the availability of a good second generation aircraft derivative engine with proven reliability and a strong commercial base, i.e., the LM-2500, was as important to the decision as was the predicted improved ship effectiveness and cost benefits. This paper discusses improvements that can be made to the twin engine, single gear, single propeller shaft system. Focusing only on this mechanical transmission concept, it addresses the impact of possible improvements to the engine, gear, and shafting. In particular, the paper discusses current LM-2500 related R&d efforts to: (a) obtain improved part-power fuel rates, (b) integrate with a reversing reduction gear, and (c) add on a waste heat recovery steam cycle. Looking ahead to the year 2000, this paper suggests that a successor to the ubiquitous LM-2500 will appear in the 15 MW power range to provide the next step in the evolution of the twin engine package. This new naval engine will most likely be based on an aircraft core that exists at present, such that it will have demonstrated its reliability and commercial potential through many hours of testing prior to its mid-1990 marine conversion. This new engine is expected to offer improved air flow, an excellent fuel rate (approaching a flat 0.30 LB/HP-HR), and effective maintenance monitoring, all at some expense in size, weight, and cost. The year 2000 engine will burn a liquid hydrocarbon fuel similar to JP-5 because of its aircraft origins. Combined with advances in gear and shafting technology, the full twin engine propulsion system of the year 2000 should be markedly lighter, smaller, and more efficient than today's units.
A field study was initiated to learn about the effects of various telephone transmission and switching conditions on the algorithms currently used in the Bell Laboratories, Linear Predictive Coding (LPC)-based, isolat...
A field study was initiated to learn about the effects of various telephone transmission and switching conditions on the algorithms currently used in the Bell Laboratories, Linear Predictive Coding (LPC)-based, isolated word recognizer. digit recordings were obtained from customers over a variety of transmission facilities. during a 23-day recording period a total of 11,035 isolateddigits were recorded. For each recording, statistics were recorded about the line condition, the background environment, and the customer's ability to speak his/her telephone number as a sequence of isolateddigits. Also recorded was information about the ability of the automatic word end-point detector to find each spoken digit and to accurately determine the correct endpoints. The results of several recognition tests are presented—one using a previously defined set of laboratory-createddigit reference templates, and several others using new sets of reference templates from a subset of the recordeddigits. The performance of the recognizer is poor (average digit accuracy of 77.4 percent) using the laboratory template set, but improves substantially (average digit accuracy of 93.1 percent) for a template set created from the field recordings. The reasons for this improvement in digit recognition accuracy are presented, along with their implications to future work in isolated word recognition.
In this paper, we introduce two new kinds of biased search trees: biased, a, b trees and pseudo-weight-balanced trees. A biased search tree is a data structure for storing a sorted set in which the access time for an ...
In this paper, we introduce two new kinds of biased search trees: biased, a, b trees and pseudo-weight-balanced trees. A biased search tree is a data structure for storing a sorted set in which the access time for an item depends on its estimated access frequency in such a way that the average access time is small. Bent, Sleator, and Tarjan were the first to describe classes of biased search trees that are easy to update; such trees have applications not only in efficient table storage but also in various network optimization algorithms. Our biased a, b trees generalize the biased 2, b trees of Bent, Sleator, and Tarjan. They provide a biased generalization of B -trees and are suitable for use in paged external memory, whereas previous kinds of biased trees are suitable for internal memory. Our pseudo-weight-balanced trees are a biased version of weight-balanced trees much simpler than Bent's version. Weight balance is the natural kind of balance to use in designing biased trees; pseudo-weight-balanced trees are especially easy to implement and analyze.
作者：
BAYER, RRonaldBayer
Ph.D. is associate for policy studies at The Hastings Center. This article is based on work of The Hastings Center's Occupational Health Research Group which is supported by grants from the Field Foundation the March of Dimes Birth Defects Foundation the Ethics and Values in Science and Technology Program of the National Science Foundation and the National Endowment for the Humanities.
作者：
GOOdMAN, MJGOOdMAN, LEMadeleineJ. Goodman
Ph.D.is Director Women's Studies Program and associate professor General Science and Women's Studies University of Hawaii. She is also principal data analyst of the Hawaii Breast Cancer Detection Project. LennE. Goodman
D. Phil.is professor of philosophy University of Hawaii. His most recent book isMonotheism: A Philosophic Inquiry into the Foundations of Natural Theology and Ethics.
Exact isomorphisms with formal systems which employ the standard linguistic notations are established for Spencer-Brown's primary algebra and F. J. Varela's calculus for self-reference. The primary algebra is ...
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作者：
CALANTONE, RCOOPER, RGAssociate Dean
Director of Research and Ph.D. Program and Associate Professor of Marketing and Management Science Robert G. Cooper is Associate Dean
Director of the MBA Program and Associate Professor of Marketing both in the Faculty of Management McGill University.
New product development and launch is a critical but high risk corporate endeavor. This article examines almost 200 industrial new product introductions in order to identify the ingredients of new product success. A c...
New product development and launch is a critical but high risk corporate endeavor. This article examines almost 200 industrial new product introductions in order to identify the ingredients of new product success. A categorization scheme, involving scenarios of new products, is developed from the data, and proves useful in assessing the merits anddangers of various types of new product projects.
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