1,721,021 research outputs found
KALMAN FILTER APPROACH TO SOLUTION OF RATIONAL-EXPECTATIONS MODELS
No full textThe solution of forward looking dynamical models for economical systems consists in finding a suitable expression of the forcing term describing the agents expectations on the future behaviour of the involved economical variables. In this paper, such a control function is estimated by a Kalman filtering technique which allows us to exploit just the current informations. The solution obtained is shown to be an asymptotically stationary process with finite steady-state covariance
Methodological Aspects of Ring Network Design
No full textWe analyse ring network design problems, with the aim of satisfying at a minimum cost a given demand matrix. The network model considers link capacities ranging over a discrete set of values, and both fixed and linear costs, which pose severe limitations to the possibility of finding global optimum solutions. An approximated version of the problem — which neglects the discrete nature of link capacities — is here formulated as a multicommodity flow problem with linear cost function and fixed costs on a hypergraph. Such a problem is NP-hard. A greedy algorithm, which extends the one proposed by Minoux, is devised. A more general solution approach is also developed, which consists of a decomposition of the general problem into two major steps. Aim of the first is to design a partial network which satisfies a given percentage of the overall demand. This task is formulated as a pure combinatorial problem, in terms of 0–1 linear programming. The second step consists of finding a completion of the partial network, and can be formulated as a classical multicommodity graph-flow problem with fixed costs. Prior to both approaches, effective cluster analysis techniques are suggested for reducing the input size, according to demand, and/or to geographical, logical, and economic criteria
Evaluation of new Internet techniques and technologies
No full textThe current Internet boom is an important event in the world of telecommunications, and promises to be a key enabler for the spread of applications based on the use of services provided by computer networks. The new commercial possibilities and the shrinking costs of the corporate networks based on the Internet paradigm - the intranets - are driving a convergence of interests at the international level in this sector. Nevertheless, today's Internet, with its protocols and equipment, is not yet able to meet all of the performance and functional requirements for actual commercial use. The scientific community and industry are now investigating new technological and technical proposals which will lead to a new generation of network elements and systems-related solutions capable of providing enhanced performance and expanding the range of available services. The paper begins with an analysis of the major proposals for innovative network elements, presenting the salient features of each. The second part of the paper concentrates on an evaluation of multicasting and caching, two of the most significant techniques adopted on the network to improve performance on the World Wide Web
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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