1,721,009 research outputs found
Applying Data Mining Techniques to Intrusion Detection in Wireless Sensor Networks
No full textWireless Sensor Networks (WSNs) have become a hot research topic in recent years. They have many potential applications for both civil and military tasks. However, the unattended nature of WSNs and the limited computational and energy resources of their nodes make them susceptible to many types of attacks. Intrusion detection is one of the major and efficient defence methods against attacks in a network infrastructure. Intrusion Detection Systems can be seen as the second line of defence and they complement the security primitives that are adopted in order to prevent attacks against the computer network being protected. The peculiar features of a wireless sensor network pose stringent requirements to the design of intrusion detection systems. In this paper, we propose a hybrid, lightweight, distributed Intrusion Detection System (IDS) for wireless sensor networks. This IDS uses both misuse-based and anomaly-based detection techniques. It is composed of a Central Agent, which performs highly accurate intrusion detection by using data mining techniques, and a number of Local Agents running lighter anomaly-based detection techniques on the motes. Decision trees have been adopted as classification algorithm in the detection process of the Central Agent and their behaviour has been analysed in selected attacks scenarios. The accuracy of the proposed IDS has been measured and validated through an extensive experimental campaign. This paper presents the results of these experimental tests
A novel security information and event management system for enhancing cyber security in a hydroelectric dam
No full textSecurity information and event management (SIEM) systems are increasingly used to cope with the security challenges involved in critical infrastructure protection. However, these systems have several limitations. This paper describes an enhanced security information and event management system that (i) resolves conflicts between security policies; (ii) discovers unauthorized network data paths and appropriately reconfigures network devices; and (iii) provides an intrusion- and fault-tolerant storage system that ensures the integrity and non-forgeability of stored events. The performance of the enhanced system is demonstrated using a case study involving a hydroelectric dam. The case study considers an attack model that affects portions of the information technology infrastructure of the hydroelectric dam and demonstrates that the security information and event management system is successfully able to detect and respond to attack
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
An LBT view of the Andromeda's satellite galaxies
Full text linkResults are presented on deep (V â1⁄4 26.5 mag) time series observations of four dwarf spheroidal galaxies (dSphs) in the Andromeda (M31) complex, namely, And XIX, And XXI, And XXV and And XXVII, that we have observed with the Large Binocular Telescope (LBT). We discovered in these galaxies a total of over 200 RR Lyrae stars and 19 Anomalous Cepheids. We also characterised the stellar populations and the spatial distributions of these dSphs
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
RR Lyrae stars as standard candles in the Gaia Data Release 2 Era
Full text linkWe present results from the analysis of 401 RR Lyrae stars (RRLs) belonging to the field of the Milky Way (MW). For a fraction of them multiband (V, Ks, W1) photometry, metal abundances, extinction values, and pulsation periods are available in the literature and accurate trigonometric parallaxes measured by the Gaia mission alongside Gaia G-band time-series photometry have become available with the Gaia Data Release 2 (DR2) on 2018 April 25. Using a Bayesian fitting approach, we derive new near-, mid-infrared period-absolute magnitude-metallicity (PMZ) relations and new absolute magnitude-metallicity relations in the visual (MV-[Fe/H]) and G bands (MG-[Fe/H]), based on the Gaia DR2 parallaxes. We find the dependence of luminosity on metallicity to be higher than usually found in the literature, irrespective of the passband considered. Running the adopted Bayesian model on a simulated data set we show that the high-metallicity dependence is not caused by the method, but likely arises from the actual distribution of the data and the presence of a zero-point offset in the Gaia parallaxes. We infer a zero-point offset of -0.057 mas, with the Gaia DR2 parallaxes being systematically smaller. We find the RR Lyrae absolute magnitude in the V, G, Ks, and W1 bands at metallicity of [Fe/H] = -1.5 dex and period of P = 0.5238 d, based on Gaia DR2 parallaxes to be MV = 0.66 ± 0.06 mag, MG = 0.63 ± 0.08 mag, M_{K_s}=-0.37± 0.11 mag, and MW1 = -0.41 ± 0.11 mag, respectively
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