1,720,958 research outputs found
Session mobility in the mockets communication middleware
No full textTaking advantage of the benefits of modern networking, a growing number of users are exhibiting mobile behavior. As they roam between different network localities, they access the Internet and the Web exploiting both wired and wireless communications and using several heterogeneous devices. Mobile users want to access their subscribed services anywhere, anytime, and want to preserve their currently opened service sessions as they roam between different network localities or switch between different devices. Mobile userspsila requirements call for novel middlewares to provide support for mobility on top of the traditional Internet infrastructure. In this context, we have developed Mockets, a communication middleware specifically designed to address the challenges of wireless networks and mobile computing. In particular, Mockets supports session mobility in terms of seamless handover for preservation of end-to-end connectivity in spite of node mobility, automatic detection and exploitation of best available connectivity, and migration of service session endpoints from one node to another
Seamless network migration using the Mockets communications middleware
No full textDue to the underlying dynamic nature of wireless and ad-hoc communication environments, applications in tactical networks have to cope with network disconnections and communication channel degradations. Support for network migration, i.e., the ability of a node to seamlessly change its network attachment point without disrupting service sessions, is therefore essential to provide seamless connectivity to warfighters and unmanned autonomous systems. This much needed utility calls for novel middleware to provide mobility functions on top of the traditional communication infrastructure. The goal of this paper is to present the network migration support in Mockets, a communication middleware specifically designed to address the needs of tactical environments by providing handover capabilities transparently and seamlessly to applications. Mockets automatically takes advantage of the best available network, leveraging on predefined, as well as user-provided, policies to perform migration decisions according to the current network status. The performance tests we conducted demonstrate the effectiveness of our implementation and show that Mockets-based network migrations cause an average measured downtime of 17 milliseconds. From a user's perspective, this short interval makes service appear uninterrupted
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
Communications Middleware for Tactical Environments: Observations, Experiences, and Lessons Learned
No full textTactical networking environments present significant challenges that must be overcome in order to effectively support net-centric warfare. The wireless and ad hoc nature of these networks implies unreliable connectivity, limited bandwidth, and variable latency. Past and current research has focused on physical and data link layers, routing protocols, transport protocols, and cross-layer aspects. However, significant work is needed at the upper layers to better support application requirements. In our experience, achieving effective communications in tactical environments requires taking into account application requirements and communication patterns, designing a rich interface between the application and communication layers, and realizing a communications middleware specifically adapted to tactical networks. In this article, we report on our observations from several tactical networking experiments and demonstrations and the lessons learned from deployment of the Mockets middleware to support tactical communications. We hope these experiences are useful to others designing and implementing applications and systems for tactical environments
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
Multiple-UAV coordination and communications in tactical edge networks
No full textUnmanned aerial vehicles are becoming prevalent in tactical networks as they are proving to be an extremely flexible platform for a variety of applications. Increasingly, UAVs need to cooperate with each other in order to perform complex tasks such as target monitoring and prosecution, information gathering and processing, and delivery between disconnected portions of the network. However, UAV cooperation in tactical scenarios represents a major challenge from both the coordination and communication perspectives. In fact, cooperating UAVs must achieve a high degree of coordination in order to accomplish complex tasks in a dynamic and uncertain environment. In turn, as UAVs interact with other entities, the effective coordination of multiple-UAV operations requires specific support in terms of efficient communication protocols and mechanisms exploiting UAVs as mobile assets that facilitate and hasten critical information flows. This article presents a series of considerations and lessons learned that we have collected in our experience with multiple- UAV coordination and communications in tactical edge networks, and discusses some of the main components of a middleware we specifically designed to support multiple-UAV operations
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