Selectivity nomographs for classical filters     

Claude S. Lindquist  Celestino A. Corral 《Journal of The Franklin Institute》2002,339(1):61-76

Nomographs for determining the filter order of classical filters based on selectivity requirements are presented. The selectivities for a variety of standard classical filters are summarized in equation form and the general selectivity nomograph is constructed. The selectivity equations are then converted into nomograph form by applying the relationship between the transfer function and the response slope. Design examples are presented to demonstrate the usefulness of the selectivity nomographs. These nomographs can be used to gauge filter performance and combined with optimization techniques can yield superior classical filter designs.  相似文献   

Query processing in a retrospective document retrieval system that uses word fragments as language elements     

E.J. Schuegraf  H.S. Heaps 《Information processing & management》1976,12(4):283-292

The structure of a retrospective information retrieval system that uses equifrequent word or text fragments is described, and its advantages over word oriented systems are mentioned briefly. Word fragments are proposed as retrieval elements, and a discussion is given of the changes required in order to process a query. Some necessary modifications in the treatment of logical operators are described, and two conditions are postulated as necessary for the successful operation of the system. Aspects of query processing are illustrated by experimental results obtained from single and two-term queries applied to a portion of the MARC tapes.  相似文献   

The treatment of uncertainty in the sciences     

Dennis H. Rouvray B.Sc.  ARCS  Ph.D.  DIC 《Endeavour》1997,21(4):154-158

For some 300 years the modelling of uncertainty in the sciences has been totally dominated by probabilistic methods. Now, following major criticism of the theoretical foundations of probability theory, other approaches to dealing with uncertainty are being explored.  相似文献   

三元能量对人的心理健康作用的比较研究     

王极盛  赫尔实  刘玉珠 《人天科学研究》1996,(5)

为了探讨三元能量对人体作用的效应,采用症状自评量表(SCL-90),对运化三元能量水平不等的元极学学习者进行问卷调查,并作了统计学分析。结果表明,三元能量可从某些方面提高人体健康水平。  相似文献   

基于机器学习的Web链接的抽取   总被引：1，自引：0，他引：1  

朱红灿  邹凯 《情报理论与实践》2007,30(2):252-255

互联网网页是通过超链接连接起来的,为人们的日常生活和商务用途提供了非常丰富的信息资源。链接结构分析在万维网的很多研究领域发挥着越来越重要的作用。然而存在着许多与主题无关的链接,造成了主题漂移。本文分析了链接本身的特点,介绍了一种有监督机器学习方法自动地抽取网页中的相关链接。试验结果表明该算法具有实用的价值。  相似文献   

Abstractive headline generation using WIDL-expressions     

R. Soricut  D. Marcu 《Information processing & management》2007,43(6):1536

We present a new paradigm for the automatic creation of document headlines that is based on direct transformation of relevant textual information into well-formed textual output. Starting from an input document, we automatically create compact representations of weighted finite sets of strings, called WIDL-expressions, which encode the most important topics in the document. A generic natural language generation engine performs the headline generation task, driven by both statistical knowledge encapsulated in WIDL-expressions (representing topic biases induced by the input document) and statistical knowledge encapsulated in language models (representing biases induced by the target language). Our evaluation shows similar performance in quality with a state-of-the-art, extractive approach to headline generation, and significant improvements in quality over previously proposed solutions to abstractive headline generation.  相似文献   

Innovation and technical change: A case study of the U.K. tractor industry, 1957 1977     

M. Gibbons  R. Coombs  P. Saviotti  P.C. Stubbs 《Research Policy》1982,11(5):289-310

In previous work it was established that the U.K. tractor industry was characterised by a high degree of technical change and that this was brought about by a process of more or less continuous incremental innovation. What was lacking was an analysis of how much technical change had been introduced and an indication of the role played by technical change in determining the performance of the U.K. tractor industry internationally. This paper concludes that on the average technical change in the industry had increased by as much as 150 percent during the years 1959–1977, though there is some indication that the rate of change might now be slowing somewhat.In order to determine the relative importance of technical change a method was developed to operationalise the distinction between price and non-price competition as well as the idea of intrinsic (technical) and associative (non-technical) factors as constituents of the latter. Based on cross-sectional data for the year 1978, it has been possible to show that British manufacturers tend to produce moderately priced tractors of low to medium technical sophistication: that German manufacturers produced the most technically sophisticated tractors; that the Italian manufacturers are not generally more sophisticated, technically, than the British producers except with respect to their development of four-wheel drive; and that COMECON-based producers combine a very low price with some degree of technical sophistication. Finally, it has been possible to show that the tractors with the highest sales are among the less sophisticated in each of the power ranges investigated and that new entrants used technical sophistication as an element of their entry strategy. The answer to the question of what allows the market leader to be market leader required the development of measures for associative non-price factors, such as the availability of a dealer network brand loyalty, resale prices of tractor models, etc. By performing a regression analysis on these measures along with previously derived measures of quality-adjusted price and relative technical sophistication it has been possible to show that market leadership is achieved as a result of a balance of a number of factors, the most important of which are the size of the dealer network, warrants cost, advertising, technical sophistication and price.  相似文献   

On orthogonal polynomials     

E.I. Jury  S.M. Ahn 《Journal of The Franklin Institute》1975,300(3):169-173

A study is made of the orthogonal polynomials on certain curves in the complex plane. Necessary and sufficient conditions for a set of polynomials to be orthogonal on the curves are obtained in terms of symmetric matrices. The relations of the symmetric matrices to Toeplitz matrices and innerwise matrices are shown.  相似文献   

Techniques in partial differential equations: Clive R. Chester. 440 pages,diagrams, 6x9 in. New York,McGraw-Hill, 1971. Price $14.95 (approx. £5.65).     

William F. Ames 《Journal of The Franklin Institute》1973,296(2):155-157

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A sensitometric study of the reduction of developing-out papers     

Loyd A. Jones  C.E. Fawkes 《Journal of The Franklin Institute》1921,191(4):503-516

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