共查询到20条相似文献，搜索用时 437 毫秒
1.
Pranas Zunde 《Information processing & management》1981,17(6):341-347
The empirical import of Shannon's Information Theory and its impact on information science are discussed. It is argued that extension of the scope of Information Theory as well as development of new theories of information science presupposes better understanding of relevant empirical regularities and laws. Possibilities of broadening the empirical foundation of Information Theory by introduction of appropriate least effort criteria are discussed. 相似文献
2.
The law is a near perfect application area for knowledge representation. Legal knowledge representation is needed in conceptual legal information retrieval systems and in legal reasoning systems. We review the knowledge representation aspects of four such systems: Waterman and Peterson's Legal Decisionmaking System, Hafner's Legal Information Retrieval System, McCarty's TAXMAN, and the deBessonet representation of the Louisiana Civil Code (CCLIPS). 相似文献
3.
Miranda Lee Pao 《Information processing & management》1985,21(4):305-320
Instead of the commonly accepted inverse square law, Lotka's original formulation was based on a more general inverse power law: xn·y = c. The exponent and the constant must be estimated from the given set of author productivity data. A step-by-step outline is presented for testing the applicability of Lotka's law. Steps include the computation of the values of the exponent and the constant based on Lotka's method, and the test for significance of the observed frequency distribution against the estimated theoretical distribution derived from Lotka's formula. 相似文献
4.
Ovad Mansur 《Information processing & management》1980,16(3):129-137
This paper extends Goffman's Indirect Method of Information Retrieval by suggesting a more flexible search strategy. The suggested strategy in its simplified version is more effective than the Boolean strategy used in existing information retrieval systems and can be implemented at comparable costs. Some of its features might further increase the effectiveness of information retrieval systems. 相似文献
5.
This paper deals with the computation of the values of two functionals which are defined over the sample paths of a randomly rotating rigid body. It is assumed that the body is subjected to two different kinds of perturbation. The first kind of perturbation is represented by the standard Wiener process and the second kind by a homogeneous process with independent increments, finite second-order moments, mean zero and no continuous sample functions. In order to measure quantitatively the stochastic stability of the body's motion, two functionals are defined over its sample paths. It is shown that each of these functionals is a solution to a corresponding partial integro-differential equation. A numerical procedure for the solution of these equations is suggested, and its efficiency and applicability are demonstrated with examples. 相似文献
6.
A set of the block pulse functions is applied to solve the Fredholm's and the Volterra's integral equations of the second kind. An algebraic equation in matrix form which is equivalent to the solution of the integral equation is developed. The approximate results are easily obtained by a few computations. An accurate solution canbe evaluated in a digital computer by solving the algebraic equation. Two examples are given. 相似文献
7.
Dale B. Cherchas 《Journal of The Franklin Institute》1981,312(1):31-40
The probability of wheel climb commencing is calculated using Nadal's formula as a basis. In particular, the functional form of Nadal's formula is maintained with normal probability density functions used to describe the two arguments in Nadal's formula, namely contact plane angle and coefficient of friction at the contact point. The theoretical value of the probability of wheel climb commencing for a given lateral/vertical force ratio value at the wheel flange–railhead interface is then compared with experimental results for positive angles of attack. Theoretical results for negative angles of attack are generated for several cases. 相似文献
8.
The analysis of the asynchronous behavior of the hysteresis machine is undertaken based on a model describing its cylindrical structure. Assuming that the hysteresis shell of the rotor is manufactured out of materials with finite conductivities, the influence of the induced eddy- currents on the machine performance is pointed out via Maxwell's equations and Poynting's theorem. The characteristics of the machine are computed as functions of slip and three interesting limiting cases are revealed. 相似文献
9.
An analysis of the asynchronous behavior of the hysteresis machine is undertaken based on a “rectified” model of its structure. The hysteresis shell and the yoke of the rotor are assumed as being manufactured out of materials with finite conductivities. The field analysis undertaken via Maxwell's equations and Poynting's theorem shows the influence of the induced eddy currents on the machine performance at nonvanishing slips. The characteristics of the machine are computed as functions of slip, revealing three particularly interesting cases. 相似文献
10.
Dean Karnopp 《Journal of The Franklin Institute》1982,314(5):265-270
Holonomic systems can be represented by a bond graph in which inertial variables are related to generalized variables using a multiport displacement-modulated transformer structure. It is shown that the part of the generalized forces due to inertial elements can be found either by direct calculation or by the operations of Lagrange's equations. Although no gyrators are needed for the representation, gyrational coupling may exist. Alternative representations may involve gyrators explicitly and it is possible to construct kinetic co-energy functions for these gyrators for use in Lagrange's equations. 相似文献
11.
12.
F.M. Reza 《Journal of The Franklin Institute》1984,317(2):57-71
The scalar versions of Schwarz's Lemma have been extensively employed in the classical development of the synthesis of lumped RLC driving-point impedance function. A vector space generalization of Schwarz's Lemma, particularly suitable for application to linear passive n-port impedance functions, is derived in this paper. The concept of power dominant networks is introduced and a number of power inequalities derived. 相似文献
13.
Ovad Mansur 《Information processing & management》1980,16(3):139-153
Identifying and representing the content of a document was, and still is, one of the main concerns of information retrieval systems. Representation of content is not dependent of the search strategy and other elements of information retrieval systems (IRS) but rather has some relationship with them.In the conventional IRS, each document in the file is characterized by one or more index terms which supposedly describe its content. Those terms are assigned from the natural language or from a pre-prepared list (Thesaurus). Over the years, other means of representing content were suggested. Also, attempts were made to combine several of them assuming independence.This paper discusses the attributes of the items in the data-base and their qualities. It seems that there is no single one which has all the desired qualities.If the attributes are not totally independent neither highly correlated then combining them in a certain way may increase effectiveness. The justification for this comes from the users' information seeking behavior—users are using index terms, author's names, citations, and other attributes in their searches.A model to accomodate the above hypothesis is formulated and the small experiment performed indicates that the hypothesis may be true, and this way of combining might improve effectiveness. 相似文献
14.
S.E. Robertson 《Information processing & management》1977,13(4):247-251
Gebhardt's[1] probabilistic model of relevance is examined and found not to represent adequately some characteristics of the relevance judgement process. An alternative model is proposed, which identifies two different types of “error” or probabilistic variation between relevance judgements. The two types arise from, first, the definition of the boundaries of the relevance classes, and secondly the actual assessment of an individual document on the underlying scale (which is assumed to be a continuum). The problems of quantifying the model, and of assessing its implications for retrieval testing, are discussed. 相似文献
15.
The implementation of relevance feedback explored here demonstrates the feasibility of query reformulation for boolean retrievals. Improvements to a term prevalence formula used in earlier research are presented along with experimental results that confirm the crucial role of term weights in relevance feedback. In particular, the weighting formula presented here differs significantly from those used by researchers in associative retrieval environments by giving equal weight to a patron's judgements of nonrelevance. The use of negative feedback—by NOTing terms in the negative prevalence range—failed to improve precision, a result that is also considered significant. 相似文献
16.
A binary approach to data storage and retrieval is introduced. It views the data base as a two-dimensional matrix that relates entities to all possible values the attributes of these entities may take. As such, it provides a unified solution to the two conflicting types of data base transactions—operational and managerial. An analytical investigation of the feasibility of binary storage and a compression method for reducing meaningless areas of the matrix are presented. Storage efficiencies of binary and conventional inverted file methods are compared and evaluated. An analysis of retrieval considerations associated with the binary matrix is given, particularly the issue of going from high to low orders of compression. Results of these analyses indicate that the binary data base's efficiency increases with increases in query complexity. Future research directions are sited and discussed. 相似文献
17.
N.G. Zamani 《Journal of The Franklin Institute》1981,311(5):311-321
In this paper we construct a collection of vector functions which are later used as a basis in finding a least squares finite element approximation to Navier's equation. Through ideas from potential theory, pointwise convergence is demonstrated. 相似文献
18.
Tadao Murata 《Journal of The Franklin Institute》1980,310(1):41-50
This paper is concerned with the applicability of network theory to those aspects of distributed/parallel processing that can be modeled by marked graphs. First, several examples are given to illustrate that a wide variety of computation schemes can be modeled by marked graphs. Subsequently, the following topics are discussed: application of KVL to fault detection and isolation, KCL and Tellegen's Theorem applied to marked graphs, and the relationship between the maximum (minimum) storage requirement and the minimum (maximum) power. 相似文献
19.
We present Biased LexRank, a method for semi-supervised passage retrieval in the context of question answering. We represent a text as a graph of passages linked based on their pairwise lexical similarity. We use traditional passage retrieval techniques to identify passages that are likely to be relevant to a user’s natural language question. We then perform a random walk on the lexical similarity graph in order to recursively retrieve additional passages that are similar to other relevant passages. We present results on several benchmarks that show the applicability of our work to question answering and topic-focused text summarization. 相似文献
20.
James L. Dolby 《Information processing & management》1977,13(1):69-77
One of the fundamental problems in information science is to distinguish various objects (such as books or journal articles) on the basis of associated values (such as authors and titles). Where the values fail to distinguish two distinct objects we say that the objects are ambigious under the given value assignment. To obtain a measure of ambiguity, it is only necessary to count the number of ways that the objects can be arranged for each set of ambiguous objects, multiply these counts and take logarithms. It is shown that such an approach leads to a measure in the formal sense and that the measure depends only on the definition of equality of values so that it can be simply extended to sets of values and ordered sets of values. It is also shown that it is possible to construct a function of ambiguity that one can call “information” and that the information loss that occurs when distinct values are grouped into equivalence classes (as in the use of search and sort keys) is also a measure. Finally, it is shown that ambiguity and information as here defined are directly related to Shannon's definition of “information” thus tieing this approach to that portion of information theory associated with the derivation of optimal distributions frequently used in information science models. 相似文献