1,720,974 research outputs found
Solving ambiguities in MDS relative localization
No full textMonitoring teams of mobile nodes is becoming crucial in a growing number of activities. Where it is not possible to use fixed references or external measurements, one of the possible solutions involves deriving relative positions from local communication. Well-known techniques such as trilateration and multilateration exist to locate a single node although such methods are not designed to locate entire teams. The technique of Multidimensional Scaling (MDS), however, allow us to find the relative coordinates of entire teams starting from the knowledge of the inter-node distances. However, like every relative-localization technique, it suffers from geometrical ambiguities including rotation, translation, and flip. In this work, we address such ambiguities by exploiting the node velocities to correlate the relative maps at two consecutive instants. In particular, we introduce a new version of MDS, called enhanced Multidimensional Scaling (eMDS), which is able to handle these types of ambiguities. The effectiveness of our localization technique is then validated by a set of simulation experiments and our results are compared against existing approaches
Hard Constant Bandwidth Server: Comprehensive formulation and critical scenarios
No full textThe Constant Bandwidth Server (CBS) is one of the most used algorithms for implementing resource reservation upon deadline-based schedulers. Although many CBS variants are available in the literature, no proper formalization has been proposed for the CBS in the context of hard reservations, where it is essential to guarantee a bounded-delay service across applications. Existing formulations are affected by a problem that can expose the system to dangerous deadline misses in the presence of blocking. This paper analyzes such a problem and presents a comprehensive and consistent formulation of the CBS for hard reservation scenarios. An overview of the contexts in which a hard CBS can be applied is also provided, focusing on the impact that previous formulations can have on schedulability, when used in conjunction with specific resource sharing protocols or other scheduling mechanisms that may cause a server to block
Probabilistic Deadline Miss Analysis of Real-Time Systems Using Regenerative Transient Analysis
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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
Optimal Design for Reservation Servers under Shared Resources
No full textModularity and hierarchical-based design are crucial features that need to be supported in complex embedded systems characterized by multiple applications with timing requirements.Resource reservation is a powerful scheduling mechanism for achieving such goals and providing temporal isolation among different real-time applications. When different applications share mutually exclusive resources, a precise feasibility analysis can still be performed in isolation, using specific resource access protocols, taking into account only the application features and the reservation parameters. This paper presents a methodology for selecting the parameters of each reservation in order to guarantee the feasibility of the served applications and minimize the required bandwidth
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