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Teletraffic analysis and computer performance evaluation proceedings of the international seminar held at the Centre for Mathematics and Computer Science ( CWI ) June 2-6, 1986, Amsterdam, The Netherlands
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
The Cramér-Lundberg Model and its Variants:A Queueing Perspective
No full textThis book offers a comprehensive examination of the Cramér–Lundberg model, which is the most extensively researched model in ruin theory. It covers the fundamental dynamics of an insurance company's surplus level in great detail, presenting a thorough analysis of the ruin probability and related measures for both the standard model and its variants.Providing a systematic and self-contained approach to evaluate the crucial quantities found in the Cramér–Lundberg model, the book makes use of connections with related queueing models when appropriate, and its emphasis on clean transform-based techniques sets it apart from other works. In addition to consolidating a wealth of existing results, the book also derives several new outcomes using the same methodology.This material is complemented by a thoughtfully chosen collection of exercises. The book's primary target audience is master's and starting PhD students in applied mathematics, operations research, and actuarial science, although it also serves as a useful methodological resource for more advanced researchers. The material is self-contained, requiring only a basic grounding in probability theory and some knowledge of transform techniques
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Polling models : from theory to traffic intersections
Get PDFThe subject of the present monograph is the study of polling models, which are queueing models consisting of multiple queues, cyclically attended by one server. Polling models originated in the late 1950s, but did not receive much attention until the 1980s when an abundance of new applications arose in computer networks and in communication protocols. The name polling model originates from this application area, where central bank computers serve ("poll") their branch terminals in a cyclic fashion. Because of this renewed practical relevance, a huge literature on polling models has appeared throughout the years. The contribution of the present monograph is twofold. Firstly, it introduces polling models with features that are well-known in the context of single-queue systems, but have remained unexplored in polling systems. For example, we study polling models with customer priority levels, impatience and abandonments, and varying arrival rates. The second contribution is to provide a new approach to analyse vehicle actuated traffic intersections with exhaustive service, by applying and extending recent results in the polling literature. The thesis is divided into three parts. The first part, which starts after a general introduction and an extensive literature review, studies different types of customer behaviour in polling models. In particular, smart, stupid, and impatient customers are discussed. In the second part we study system behaviour in the sense that we introduce customer priority levels and discuss several service policies based on these priority levels. The third part focusses on traffic intersections and new approaches to apply results from the polling literature to this application area. We discuss the three parts in more detail below. As stated before, Part I introduces new types of customer behaviour in polling models. In Chapter 3 we study a polling model with arrival rates that depend on the server position. This extension destroys the convenient property that an arbitrary arriving customer sees the system in equilibrium, and a novel analysis technique is required to circumvent this complication. The model is practically relevant because it allows customers to choose which queue they want to join, knowing which queue is being served at their arrival epoch. Besides the practical relevance of the model, the analysis and the insights gained from it have great merit for future studies. This is illustrated by the model studied in Chapter 4, which is an extension of a vacation model with customer impatience, studied in existing literature. Using the analysis methodology of Chapter 3, we are able to obtain new results for the vacation model, and extend it to the context of polling models. In polling models, this is the first appearance of customer impatience, in queueing literature often referred to as reneging. Part II studies system behaviour through the introduction of customer priority levels. We study the impact of changing the order in which customers are served based on these priority levels. For example, we illustrate the effect of giving higher priority to customers with less service requirement. In Chapter 5 we study priorities in a standard polling system. Chapter 6 discusses the impact of using different service disciplines for customers with different priority levels, and shows how this can be used as a strategy to give even more advantages to customers with a higher priority level. The third part of the thesis is mainly dedicated to polling models for traffic intersections. Polling models have been applied to road traffic before, but only in the situation that one lane on a single road is blocked and traffic has to share the other lane. In Chapter 7 we develop a novel closed-form waiting time approximation for polling systems. The manner in which this approximation is created lends itself perfectly for adaption to the scenario where groups of multiple queues receive service simultaneously, as is the case in signalised traffic intersections. Chapter 8 presents this adaptation for traffic signals. Another aspect that is new in the analysis of delays at traffic intersections, is the analysis of conflicting traffic flows receiving a green light simultaneously. For this purpose, we use the approximation developed in Chapter 7 in combination with the results on polling models with priorities from Chapter 5
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