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Broadband internet access for trains with quality of service by interworking of heterogeneous wireless networks
No full textHet spoorvervoer biedt nu al een betere oplossing inzake milieuvriendelijkheid en veiligheid dan andere transportmiddelen en kan in de toekomst wellicht een nog belangrijkere rol spelen.
Het aanbieden van internettoegang aan passagiers en het mogelijk maken van nieuwe of verbeterde operationele diensten, bijvoorbeeld een live videobeeld van de volgende spoorwegovergang aan de machinist tonen, kan een trein rit nog comfortabeler en veiliger maken.
Om deze dataconnectiviteit aan boord van de trein mogelijk te maken, beschouwen we het gebruik van een centraal systeem, een ‘train-to-wayside communication system’ (TWCS). We concentreren ons op een geoptimaliseerd ontwerp om vlot van de ene naar de andere netwerkoperator te kunnen overschakelen en om rekening te houden met de eigenschappen van de datastromen.
Aangezien de draadloze WiMAX technologie vaak gebruikt wordt voor een draadloos netwerk langs het spoor, modelleren we daarnaast ook de eigenlijke datasnelheid waaraan men gegevens kan verzenden in dit netwerk.
Door te focussen op het gemengd gebruik van meerdere heterogene draadloze links, het maken van een kwalitatief onderscheid tussen verschillende datastromen en het beschouwen van de eigenlijke datasnelheid waaraan men gegevens kan verzenden, behandelt dit proefschrift enkele van de grote uitdagingen voor het aanbieden van een dataverbinding tussen de trein en het vasteland.Rail transportation is already a more environmental-friendly and safer choice than most other transportation modes. Therefore, one expects that the railway industry will be even more important in the future.
Offering Internet services to passengers and enabling new or improved operational services, e.g. offering a live camera view of the next level crossing to the train driver, results in an even more comfortable and safe journey.
In order to provide this data connectivity on board trains, we consider the use of a central system, a train-to-wayside communication system (TWCS). We focus on designing an optimized TWCS to easily switch from one network operator to another and to reckon with the different data flow characteristics.
As WiMAX technology is sometimes used as a dedicated wireless trackside network, we also model the maximum achievable throughput over this wireless network.
Focusing on the interworking of multiple heterogeneous wireless links, enabling Quality of Service and considering the actual achievable throughput, the work presented in this dissertation covers some of the major challenges that are faced by Train-to-Wayside Communication Systems today
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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