1,721,081 research outputs found
Improving Log-Based Field Failure Data Analysis of Multi-Node Computing Systems
No full textLog-based Field Failure Data Analysis (FFDA) is a widely-adopted methodology to assess dependability properties of an operational system. A key step in FFDA is filtering out entries that are not useful and redundant error entries from the log. The latter is challenging: a fault, once triggered, can generate multiple errors that propagate within the system. Grouping the error entries related to the same fault manifestation is crucial to obtain realistic measurements. This paper deals with the issues of the tuple heuristic, used to group the error entries in the log, in multi-node computing systems. We demonstrate that the tuple heuristic can group entries incorrectly; thus, an improved heuristic that adopts statistical indicators is proposed. We assess the impact of inaccurate grouping on dependability measurements by comparing the results obtained with both the heuristics. The analysis encompasses the log of the Mercury cluster at the National Center for Supercomputing Applications
Identifying Compromised Users in Shared Computing Infrastructures: A Data-Driven Bayesian Network Approach
No full textThe growing demand for processing and storage capabilities has led to the deployment of high-performance computing infrastructures. Users log into the computing infrastructure remotely, by providing their credentials (e.g., username and password), through the public network and using well-established authentication protocols, e.g., SSH. However, user credentials can be stolen and an attacker (using a stolen credential) can masquerade as the legitimate user and penetrate the system as an insider. This paper deals with security incidents initiated by using stolen credentials and occurred during the last three years at the National Center for Supercomputing Applications (NCSA) at the University of Illinois. We analyze the key characteristics of the security data produced by the monitoring tools during the incidents and use a Bayesian network approach to correlate (i) data provided by different security tools (e.g., IDS and Net Flows) and (ii) information related to the users' profiles to identify compromised users, i.e., the users whose credentials have been stolen. The technique is validated with the real incident data. The experimental results demonstrate that the proposed approach is effective in detecting compromised users, while allows eliminating around 80% of false positives (i.e., not compromised user being declared compromised)
Validation and evaluation of a software solution for fault tolerant distributed synchronization
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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
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
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