1,720,970 research outputs found
SRI@work: Efficient and Effective Routing Strategies in a PDMS
No full textIn recent years, information sharing has gained much benefit by the large diffusion of distributed computing, namely through P2P systems and, in line with the Semantic Web vision, through Peer Data Management Systems (PDMSs). In a PDMS scenario one of the most difficult challenges is query routing, i.e. the capability of selecting small subsets of semantically relevant peers to forward a query to. In this paper, we put the Semantic Routing Index (SRI) distributed mechanism we proposed in [6] at work. In particular, we present general SRI-based query execution models, designed around different performance priorities and minimizing the information spanning over the network. Starting from these models, we devise several SRI-enabled routing policies, characterized by different effectiveness and efficiency targets, and we deeply test them in ad-hoc PDMS simulation environments
Semantic Query Routing Experiences in a PDMS
No full textQuerying a PDMS means either flooding the network with messages to all peers or taking advantage of a routing mechanism to reformulate a query only on the best peers selected according to some given criteria. As reformulations may lead to semantic approximations, we deem that such approximations can be exploited for locating the semantically best directions to forward a query to. In this paper, we present our experiences in devising and testing a mechanism for effective query routing in a PDMS. In particular, we describe a distributed index mechanism where each peer is provided with a Semantic Routing Index (SRI) for routing queries effectively. We illustrate SRIs’ structure, their use and the framework we devised for their incremental update, then we provide an extensive evaluation of their effectiveness through a set of query routing experiments on a variety of scenarios. This work is partially supported by the PRIN WISDOM and FIRB NeP4B national projects
Data-Sharing P2P Networks with Semantic Approximation Capabilities
No full textThe synergy between Peer-to-Peer systems and Semantic Web technologies has paved the way for large-scale sharing of semantically rich data, usually represented through schemas like, for instance, RDF or ontologies.Because of the lack of common understanding of the vocabulary used by peers, the resulting heterogeneity of data representations opens new challenges as to the efficient and effective retrieval of relevant information.In this paper, as opposed to viewing semantic misalignment as a limit for interoperability, we leverage on the presence of semantic approximations between the peers' schemas as a means for giving effective hints along two directions: 1) for query routing purposes, to identify the peers which best satisfy the user's requests, and 2) for making users aware of the relevance of the returned answers through a ranking mechanism which promotes the most semantically related results
Semantic Routing for Effective Search in Heterogeneous and Distributed Digital Libraries
No full textNext generation Digital Libraries (DLs) will offer an entire ensemble of systems and services designed to help users to easily find and access the information they are looking for. However, much work is still required in order to achieve this vision. In this paper, we concentrate our attention on devising techniques allowing an effective routing of queries, which we think can be of the utmost importance in providing effective and efficient querying in heterogeneous and distributed DLs, identifying the best ways to navigate the available nodes and, thus, the documents (or their parts) which are most suitable to best answer the user needs. We describe a routing mechanism, which we call routing by mapping, in which the query is sent to the DL peers whose subnetworks best approximate the concepts required. To this end a distributed index mechanism is adopted, which we call Semantic Routing Index (SRI). We also present some exploratory experiments showing the effectiveness of the proposed approach
SUNRISE: Exploring PDMS Networks with Semantic Routing Indexes
No full textWe demonstrate SUNRISE 1, a complete infrastructure supporting the construction of a PDMS semantic layer and providing a series of techniques that can be used for an effective and efficient exploration of a semantic network, for instance in a query answering setting
Toward a Flexible Data Management Middleware for Wireless Sensor Networks
No full textIn this paper we present the research activity we are carrying out in the "Mobile Semantic Self-Organizing Wireless Sensor Networks" Project at the Department of Information Engineering of the University of Modena and Reggio Emilia. In this context, the main aim of our research is to study solutions for the flexible querying of distributed data collected by heterogeneous devices providing measurement readings. To this end, we propose a middleware for wireless sensor networks which is able to autonomously configure the communication and the operations required to each device in order to reduce energy and temporal costs
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
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