检索结果-内蒙古大学图书馆

PERTURBATIVE SOLUTIONS OF QUANTUM MECHANICAL PROBLEMS BY SYMBOLIC COMPUTATION: A REVIEW

International Journal of Modern Physics C 1990年第1期1卷 53-76页

作者： T. C. SCOTT R. A. MOORE G. J. FEE M. B. MONAGAN G. LABAHN K. O. GEDDES Guelph-Waterloo Program for Graduate Work in Physics Waterloo Campus Canada Department of Computer Science University of Waterloo Waterloo Ontario N2L-3G1 Canada

It is shown that Symbolic Computation provides excellent tools for solving quantum mechanical problems by perturbation theory. The method presented herein solves for both the eigenfunctions and eigenenergies as power series in the order parameter where each coefficient of the perturbation series is obtained in closed form. The algorithms are expressed in the Maple symbolic computation system but can be implemented on other systems. This approach avoids the use of an infinite basis set and some of the complications of degenerate perturbation theory. It is general and can, in principle, be applied to many separable systems.

关键词： Symbolic computation Maple Quantum mechanics Perturbation theory

来源：评论

学校读者我要写书评

暂无评论

Real-time robot motion planning using rasterizing computer graphics hardware 90

Real-time robot motion planning using rasterizing computer g...

引用

Proceedings of the 17th annual conference on computer graphics and interactive techniques

作者： Jed Lengyel Mark Reichert Bruce R. Donald Donald P. Greenberg Graduate Student Program of Computer Graphics Cornell University Ithaca N.Y. Assistant Professor and Director Computer Science Robotics Laboratory Department of Computer Science 4130 Upson HalI Cornell University Ithaca N.Y. Director Program of Computer Graphics Jacob Gould Shurman Professor of Computer Graphics Cornell University Ithaca N.Y.

ISBN: (纸本)9780897913447

We present a real-time robot motion planner that is fast and complete to a resolution. The technique is guaranteed to find a path if one exists at the resolution, and all paths returned are safe. The planner can handle any polyhedral geometry of robot and obstacles, including disjoint and highly concave unions of *** planner uses standard graphics hardware to rasterize configuration space obstacles into a series of bitmap slices, and then uses dynamic programming to create a navigation function (a discrete vector-valued function) and to calculate paths in this rasterized space. The motion paths which the planner produces are minimal with respect to an L1 (Manhattan) distance metric that includes rotation as well as *** examples are shown illustrating the competence of the planner at generating planar rotational and translational plans for complex two and three dimensional robots. Dynamic motion sequences, including complicated and non-obvious backtracking solutions, can be executed in real time.

关键词：

来源：评论

学校读者我要写书评

暂无评论

ON EVALUATING BOOLEAN FUNCTIONS WITH UNRELIABLE TESTS

引用

International Journal of Foundations of computer science 1990年第1期1卷 1-10页

作者： CLAIRE KENYON ANDREW C. YAO DIMACS Center Rutgers University Piscataway NJ 08855 USA Ecole Normale Supérieure 45 rue d’Ulm 75230 Paris Cedex 05 France Research supported by the graduate exchange program between Ecole Normale Supérieure and Princeton University. Computer Science Dept Princeton University Princeton NJ 08544 USA Research supported in part by NSF under grants DCR83–08109 and CCR-8813283.

We consider the problem of evaluating a boolean function P(x 1 ,…,x n ), by asking queries of the form “x i =?”, and receiving answers which may not always be truthful. Assuming that the total number of lies does not exceed E, we present an algorithm with cost O(n+s P E+t P E), where s P is the maximal size of a minterm of P(x) and t P ‘is the maximal size of a maxterm. We also prove that if P is monotone, then any algorithm for evaluating P must ask Ω(s P E+t P E) queries for some input.

关键词： algorithms boolean functions error correction lower bounds unreliable tests

来源：评论

学校读者我要写书评

暂无评论

Note on development of modularity in simple cortical models 89

Note on development of modularity in simple cortical models

引用

Proceedings of the 2nd International Conference on Neural Information Processing Systems

作者： Alex Chernjavsky John Moody Molecular and Cellular Physiology Beckman Center Stanford University Stanford CA and Neuroscience Graduate Program Section of Molecular Neurobiology Howard Hughes Medical Institute Yale University Yale Computer Science New Haven CT

The existence of modularity in the organization of nervous systems (e.g. cortical columns and olfactory glomeruli) is well known. We show that localized activity patterns in a layer of cells, collective excitations, can induce the formation of modular structures in the anatomical connections via a Hebbian learning mechanism. The networks are spatially homogeneous before learning, but the spontaneous emergence of localized collective excitations and subsequently modularity in the connection patterns breaks translational symmetry. This spontaneous symmetry breaking phenomenon is similar to those which drive pattern formation in reaction-diffusion systems. We have identified requirements on the patterns of lateral connections and on the gains of internal units which are essential for the development of modularity. These essential requirements will most likely remain operative when more complicated (and biologically realistic) models are considered.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Is American Energy Politics Ideological?

引用

The Energy Journal 1989年第1期10卷 55 - 76页

作者： Eric M. Uslaner * Department of Government and Politics University of Maryland College Park. Support from the General Research Board of the Graduate School University of Maryland College Park the College of Behavioral and Social Sciences University of Maryland College Park the Computer Science Center of the University of Maryland College Park and the Everett McKinley Dirksen Congressional Leadership Research Center is greatly appreciated as are the comments of John E. Chubb M. Margaret Conway Pietro Nivola Karol Sollan Charles Stewart III Peter Van Doren and the editor and anonymous reviews of this journal. I also appreciate the research assistance of Rodger Payne. Kevin Ogrady provided assistance on the unfolding program while Mike Wagner was (as always) more than invaluable. I am particularly indebted to the representatives of energy interest groups who kindly gave of their time for my interviewing. This paper draws from and expands upon Uslaner (1989 ch. 5).

When we think of energy issues, we generally conjure up ideas of conflicts between producers and consumers. These translate into visions of grand ideological conflicts between the left and the right. Wildavsky and Tennenbaum (1981) speak of battles between "preservationists" and "industrialists." Kalt (1981) argues that "[tihe domestic energy 'crisis' is, far more than anything else, a quarrel over income distribution." Ideological straight fights are marked by a single dimension of conflict. In particular, ideological politics, as opposed to religious or ethnic cleavages, suggests a battle between left and right--or, producers and consumers in the case of energy battles. When there are only two contestants, one is sure to win if the group decision is made by majority rule. Even in the United States Congress, where complex rules often frustrate coherent policy formation, strongly-held positions can prevail over obstructionists if they are determined enough. Yet, during the 1970s many attempts to form a "national energy policy" failed. In the 1980s Congress again stumbled in making natural gas policy as it defeated both decontrol and recontrol proposals.

关键词：

来源：评论

学校读者我要写书评

暂无评论

BOTTOM BOUNCE ARRAY SONAR SUBMARINE (BBASS)

引用

NAVAL ENGINEERS JOURNAL 1989年第5期101卷 59-72页

作者： JACKSON, HA NEEDHAM, WD SIGMAN, DE USN (RET.) Capt. Harry A. Jackson USN (Ret.) is a graduate of the University of Michigan in naval architecture and marine engineering and completed the General Electric Company's 3-year advanced engineering course in nuclear engineering. He has been an independent consulting engineer and participated in projects involving deep submergence waste disposal water purification and submarine design both commercial and government. Cdr. William D. Needham USN is currently assigned as the repair officer of USS Hunley (AS-31) in Norfolk Virginia. He received a regular commission through NROTC at Duke University where he graduated magna cum laude in mechanical engineering. Selected for the Nuclear Power Program he served as a division officer on the USS Grayling (SSN-646) as the production training assistant at the MARE Prototype Reactor in New York and as blue crew engineer of the USS Nathan Hale (SSBN-623) where he completed the requirements to be designated qualified for command of submarines. Following line transfer to the EDO community in 1981 he completed a tour as nuclear repair officer (Code 310) at Norfolk Naval Shipyard and earned master of science in materials science and ocean engineer's degrees at MIT. His awards include the Meritorius Service Medal Navy Commendation Medal Navy Achievement Medal Spear Foundation Award and the Vice Admiral C.R. Bryan Award. Cdr. Needham also holds a master of arts degree in business management from Central Michigan University. Capt. Jackson was technical director of Scorpion Search Phase II. The on-site investigation included descending over 12 000 feet to the bottom of the ocean. He was also supervisor of one of the Navy's largest peacetime shipbuilding and repair programs. His responsibilities included supervision of design production and contract administration. Capt. Jackson was third from the top in managaement of a major shipyard and responsible for design material procurement work order and financial control of two major surface ship prototypes as well a

Anticipated technological advances in the quieting of potential adversary submarines mandate the use of increasingly effective detection systems for U.S. ASW forces. Based on the assumptions that sonar will continue to be the primary means of detection and that the effectiveness of each individual sonar element will not change markedly, one must increase the projected area of the sonar array to improve its capability. The primary SSN mission of anti-submarine warfare will hence require increasing the hull area devoted to the primary sonar detection system. A revolutionary hull form is proposed that maximizes the area available for this purpose. The advantages and disadvantages of this hull form are discussed and feasibility study level design parameters and arrangements presented.

关键词： Submarines

来源：评论

学校读者我要写书评

暂无评论

Rural‐Urban Differences in Access to Iowa Child Health Services

引用

The Journal of Rural Health 1988年第2期4卷 59-72页

作者： Levey, Linda M. Curry, James P. Levey, Samuel JAMES P. CURRY Ph.D. is Assistant Research Scientist in the Center for Health Services Research at The University of Iowa. He received his Ph.D. in Sociology from The University of Iowa. His recent publications include studies of organizational behavior in health care settings and the utilization of health ServiceS. SAMUEL LEVEY Ph.D. is Gerhard Hartman Professor and Head of the Graduate Program in Hospital and Health Administration and the Center for Health Services Research at The University of Iowa. Dr. b e y holds a doctorate in hospital and health administraton from The University of Iowa and a Master of Science from the Harvard School of Public Health. He has published extensively in the health administration literature including several textbooks and is currently the Editor of Hospital and Health saoices Administmtion.

Indicators of access, utilization, and quality of available child health services as well as health status were obtained through a telephone survey of Iowa households with children under age six. These indicators were compared for rural‐urban subsamples within an AFDC sample drawn from Iowa Department of Human Service files (N=637), and within poverty (N=129) and nonpoverty groups (N=631) drawn from the population of all households in the state with children under age six. About 55 percent of all households studied were rural. Rural households were generally larger than urban households, more likely to be intact maritally, white, and earning a living from farming. The findings support the hypothesis that place of residence has an impact on access, utilization, and quality of child health services over and above family income, although not always to the disadvantage of rural children. Typical problems for rural children, irrespective of income, were access to pediatric care, greater travel time to providers, and discontinuity of well care and sick care. Rural children in all income groups had lower seat belt use than urban children;they were also less likely to have well visits and their providers showed less attentiveness to behavioral and developmental issues at these visits. Rural residency exacerbated problems in access to care for low income children, who were less likely to be eligible for AFDC/ Medicaid than their urban counterparts. Medicaid coverage, however, did not eliminate rural‐urban differences in receiving desired medical care. Copyright © 1988, Wiley Blackwell. All rights reserved

关键词：

来源：评论

学校读者我要写书评

暂无评论

NAVAL SHIP DESIGN - EVOLUTION OR REVOLUTION

引用

NAVAL ENGINEERS JOURNAL 1988年第3期100卷 40-52页

作者： TIBBITTS, BF KEANE, RG RIGGINS, RJ Captain Barry Tibbitts USN: was graduated from the U.S. Naval Academy in 1956 and subsequently served as a gunnery division officer in an attack aircraft carrier and as gunnery officer operations officer and chief engineer in two diesel submarines. He attended MIT from 1962–1965 earning a master of science in mechanical engineering and a naval engineers degree. Early assignments as an engineering duty officer included SRF Yokosuka CINCPACFLT staff and SupShip Pascagoula. From 1976 to 1987 he served in a variety of senior ship design assignments: CVV ship design manager director NAVSEC Hull and Ship Design Divisions director NavSea Ship Design Management and Integration Office commander David Taylor Naval Ship R&D Center and director NavSea Ship Design Group. Recently retired but recalled to active duty he is the professor of naval construction and engineering at MIT. He has received seven personal decorations including two Legion of Merit awards. Robert G. Keane Jr.:is currently the deputy director of the NavSea Ship Design Group. He has been employed by NavSea and its predecessor organizations for over twenty years. He is a graduate of The Johns Hopkins University from which he received his B.E.S. degree in mechanical engineering in 1962. He received his M.E. degree in mechanical engineering in 1967 from Stevens Institute of Technology and in 1970 his M.S.E. degree in naval architecture and marine engineering from the University of Michigan. Mr. Keane held increasingly responsible design positions involving ship arrangements hull equipment hull form and hydrodynamic performance before being selected in 1981 for the Senior Executive Service to be director of the Naval Architecture Subgroup. Following an assignment at the David Taylor Research Center as assistant for transition of ship engineering technology he served as director of the Ship Survivability Subgroup until assuming his current position in 1985. He is an active member of ASNE SNAME and ASE. Robert Riggins:received a B.S. in mechanical

Some fairly radical changes to the naval ship design process occurred during the 1970s. The decade of the 80s has also witnessed a steady stream of changes. One of the most significant was the establishment of the Ship Characteristics Improvement Board (SCIB) in the Office of the Chief of Naval Operations (OpNav), and the resulting influence on the dialog between the military requirements decision makers and the Navy's ship designers. Other changes have occurred for which the impacts are less clear. These include establishment of the chief engineer of the Navy (ChEng) position, creation of the Space and Naval Warfare Systems Command (SpaWar) and OpNav's “Revolution at Sea” initiative. This paper will describe and discuss these and other changes, and comment on the resultant impact. The authors will attempt to present a global view of the total pattern of changes and try to discern if we are on a path of revolution, or merely normal evolution.

关键词： NAVAL VESSELS

来源：评论

学校读者我要写书评

暂无评论

A CONNECTED WORD RECOGNITION METHOD UTILIZING DTW AND A COARTICULATION MODEL

A CONNECTED WORD RECOGNITION METHOD UTILIZING DTW AND A COAR...

引用

1987 European Conference on Speech Technology, ECST 1987

作者： Itahashi, Shuichi Hisamatsu, Yutaka Master's Program in Science and Technology Graduate School Univ. of Tsukuba Japan Institute of Information Sciences and Electronics University of Tsukuba Japan

Coarticulation is one of the major factors that make speech recognition difficult. In conventional connected word recognition methods, a template for a connected word sequence is made by simply concatenating the templates of a single word. Therefore, some misrecognitions occur on account of this disregard for coarticulation. This study examines the influence of coarticulation in concatenating templates. The boundaries between words are smoothed so as to incorporate the influence of the tail of the preceding word on the head of the following word. The results of recognition experiments of 35 tokens of 4-digit-sequences show a recognition rate improvement of 5%, giving an 98% correct recognition rate. © European Conference on Speech Technology, ECST 1987. All rights reserved.

关键词： Speech recognition

来源：评论

学校读者我要写书评

暂无评论

Heuristic assignments of redundant software versions and processors in fault-tolerant computer systems for maximum reliability

引用

Probability in the Engineering and Informational sciences 1987年第4期1卷 457-479页

作者： Kar Leow, Soo Mcallister, David F. Graduate Program in Operations Research North Carolina State University RaleighNC27695 United States Department of Computer Science North Carolina State University RaleighNC27695 United States

We address the problem of assigning multiple copies of n independently developed versions of a program to a set of m(m > n) possibly heterogeneous processors to maximize system reliability. This problem is viewed as a partition and assignment problem. We first partition the set of processors into n clusters or subgroups. A program version is then assigned to be executed on all the processors in the cluster. This means that each processor in the cluster will execute a copy of the assigned version. The cluster's unreliability is the probability of failure of all its processors. Component i of this system is composed of the copies of version i and the assigned cluster of processors. Copyright © Cambridge University Press 1987.

关键词： Combinatorial optimization

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：