1,720,965 research outputs found
"Distributed Cognitive Sensor Network Approach for Surveillance Applications"
No full textThe application of intelligent systems composed by smart cameras is continuously spreading in a wide range of applications, playing a key role in public, military and commercial scenarios. As well, in the last years, the capability of wireless sensor networks to collect information from the environment in a distributed manner has been successfully applied in both civilian and military applications. In this paper, basing on recent studies on autonomous cognitive systems, we explore the concepts for designing interactive, adaptable and intelligent multi-sensor surveillance systems able to react to situations in a preventive way by using actuators placed in the monitored environment. To this end, taking inspiration from ambient intelligence (AmI) and cognitive radio (CR) paradigms, fusion of information provided by heterogeneous sensors is used to improve awareness regarding surrounding environment
A comparison between stand-alone and distributed architectures for spectrum hole detection
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Signal Classification based on Spectral Redundancy and Neural Network Ensembles
No full textIn the last couple of decades, the introduction of new wireless applications and services, which have to coexist with already deployed ones, is creating problems in the allocation of the unlicensed spectrum. In order to overcome such a problem, by exploiting efficiently the spectral resources, dynamic spectrum access has been proposed. In this context, cognitive radio represents one of the most promising technologies which allows an efficient use of the radio resource by collecting, processing and exploiting information regarding the spectrum utilization in a monitored area. To this end, in this paper the problem of classifying similar signals characterized by different spectral redundancies is addressed by using a neural network ensemble. A set of simulations have been carried out to prove the effectiveness of the considered algorithms and numerical results are reported
A Comparison among Cooperative Spectrum Sensing Approaches for Cognitive Radios
No full textIn this paper, a comparison among different cooperative spectrum sensing approaches is provided. It is assumed that the secondary terminals autonomously perform local spectrum sensing and forward their decision to a fusion center. It combines the received data to obtain the global decision, i.e. the presence or the absence of the primary user in the monitored environment. In particular, three fusion rules, i.e. OR, AND and optimal, are compared in terms of required processing capabilities at the fusion center and at the secondary terminals, and required control channel capacity. Numerical simulations in a practical heavy multipath environment are provided to compared the performances of the considered approaches
Performance evaluation of a multiple antenna system for spectrum sensing
No full textIn this work, a comparison between the performance of a single antenna and a multiple antenna system which have to identify two similar OFDM signals, is provided. Numerical simulations have shown that multiple antenna systems allow to obtain better performance with respect to single antenna systems with a significant reduction of the observation time, also in multipath environment
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
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