1,720,961 research outputs found
Study and implementation of simplistic spoofing countermeasures for smartphones and unmanned aerial vehicles
Get PDFL'abstract è presente nell'allegato / the abstract is in the attachmen
Improving GNSS Spoofing Awareness in Smartphones via Statistical Processing of Raw Measurements
Get PDFDue to the low received power of Global Navigation Satellite Signals (GNSS), the performance of GNSS receivers can be disrupted by anthropogenic radio frequency interferences, with intentional jamming and spoofing activities being among the most critical threats. It is reported in the literature that modern, GNSS-equipped Android smartphones are generally resistant to simplistic spoofing, and many recent contributions support such a biased belief. In this paper, we present the results of a test campaign designed to further stress the resilience of such devices to simplistic spoofing attacks and highlight their actual vulnerability. We then propose an effective spoofing detection technique, that exploits the spatial and temporal correlation of the counterfeit signals by leveraging the statistical analysis of raw GNSS measurements. By not requiring access to the low signal processing level of the GNSS receiver, the proposed solution applies to any device embedding a GNSS receiver that provides raw GNSS measurements, such as current Android smartphones. Vulnerability analysis and validation of the proposed technique were conducted in a controlled environment by transmitting realistic, counterfeit Global Positioning System L1/CA navigation signals to a variety of Android smartphones embedding also different GNSS chipsets. We show that, under proper conditions, the devices were vulnerable to the attacks and that the effects were visible through their raw measurements, i.e., Carrier-to-noise ratio , pseudo-range measurements, and position estimates. In particular, the study demonstrates that cross-correlation between the time series provided by each device for different GNSS satellites increases under spoofing conditions, thus constituting an effective metric to detect the attack within a few seconds
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
Detecting Single-antenna Spoofing Attacks by Correlation in Time Series of Raw Measurements
Get PDFGlobal Navigation Satellite System (GNSS) receivers are vulnerable to intentional radio frequency interferences, posing significant risks to their performance and reliability. Among these threats, it has been widely argued that modern GNSS-equipped AndroidTM smartphones are resilient to non-coherent spoofing attacks. This study challenges such a perception by highlighting the vulnerability of GNSS-equipped AndroidTM smartphones to single-antenna, non-coherent spoofing attacks and proposing a novel, application-level detection technique solely based on raw GNSS observables, i.e., carrier-to-noise-density time series. The analysis demonstrated the capability of successfully detecting such attacks by observing the cross-correlation among Global Navigation Satellite System (GNSS) measurements time series. Cross-correlation quantified by Pearson’s correlation coefficients shows a relevant increment during harmful spoofing attacks. Under these conditions, the proposed methodology allows to rise a spoofing alarm in about 5 seconds with a false alarm probability of 1.5%. Furthermore, the proposed technique does not require low-level signal access, making it suitable for implementation at the application layer in a large number of smart devices with limited knowledge of their low-level system architecture. A validation campaign has been performed by testing 18 different AndroidTM devices and chipsets, thus demonstrating the applicability of the proposed method independently from the device under test
Determination of Correlations of Control Punching Area of Ecall / Era-Glonass Automated Emergency Response Systems
Get PDFFor selection and design of the precise parameters of shear cutting area of ERA GLONASS system, it is crucial to know the values of acceptable force, energy and speed. Accurate values of shearing force and energy can only be obtained from the actual force-penetration characteristics for specific applications. Actual force-penetration characteristics for all varieties of metal having different compositions and in use at various temperatures are not always available. The paper describes control system (closed loop) for shear cutting are of ERA GLONASS system and their correlations. The objective is this processes are impart a desired curvature to a workpiece at each point along the length of the part. Since the final part shape is determined by the shape to which workpiece is loaded and the amount of elastic spring back and since the latter is a strong function of the material properties of the workpiece, a truly closed loop controller must be accounted for these properties to insure consistent process performance
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
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