1,721,126 research outputs found
International cloud infrastructure for space weather data management: The DemoGRAPE challenge
No full textData management for E-science applications need to adopt new platforms/services aiming at improving the interactions between users and data, through sharing, flexibility and resources availability. In the space weather domain, the DemoGRAPE project, under the GRAPE initiative (www.grape.scar.org), focuses on merging E-science and ICT to push forward international collaborations on Irregular Ionosphere investigation with GNSS signals in Polar Regions. DemoGRAPE aims at being a pilot project to improve resources and data management in different geographic sites. DemoGRAPE challenges the standard approach on data sharing and their centralized archiving. In fact, the innovative ICT architecture, based on an Open Source Cloud technology, will pursue a new way for managing data and resources: a smart choice is to move your applications and not your data. The proposed Cloud model follows the objective of the Standing Committee on Antarctic Data Management, with a specific attention on the resources configuration and deployment automation. DemoGRAPE intends to give new ideas for e-infrastructures, models and scenarios on Data Management strategy in the GNSS domain. The initiative aims at creating an innovative technological tool addressed to the radio sciences community, with the deployment of an international collaborative IT infrastructure
Travelling ionospheric disturbances detection: A statistical study of detrending techniques, induced period error and near real-time observables
Full text linkDue to advances in remote sensing of the Earth’s Ionosphere through Total Electron Content (TEC) estimates by Global Navigation Satellite System (GNSS) receivers, it is possible to detect and characterize Travelling Ionospheric Disturbances (TIDs) in both post-processing and, to some extent, in near real-time (NRT). A reliable and precise TEC filtering technique must be adopted to characterize waves accurately. Specifically, TEC detrending is widely adopted to extract the amplitude and period of the detected ionospheric waves from the background ionospheric conditions. Therefore, this study aims to understand and compare how different TEC detrending techniques and their settings impact the ability to extract such parameters. We highlight that the novel Fast Iterative Filtering (FIF) and the Savitzky-Golay filter (SGOLAY) techniques are the most reliable overall compared with moving average (MA), multi-order numerical difference (DD), polynomial detrending (POLY) and Finite Impulse response (FIR) band-pass filter (BUTF). Moreover, the impact of general algorithm settings on the exracted TID period is investigated, such as the Ionospheric Piercing Point (IPP) height and elevation cut-off angle, showing that such parameters drastically impact the retrieved period, especially for slower TIDs. Finally, due to the growing interest in real-time (RT) detection and classification of TIDs, the study proposes techniques for accurately estimating the TID amplitude in an NRT scenario. Such NRT techniques are then compared with the widely used post-processing products, such as the calibrated vertical TEC (vTEC), showing a difference that is mostly lower than the typical noise level of GNSS receivers (0.05 TECu)
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
Monitoring the Effects of the October 10-11 Solar Storm at Mid-Latitudes Using a GNSS SDR Receiver
Full text linkThe October 10–11, 2024, geomagnetic storm, one of the most intense of solar cycle 25, significantly impacted ionospheric conditions at mid-latitudes. In this study, we analyze the effects of this storm on Global Navigation Satellite System (GNSS) signals using a Software-Defined Radio (SDR)-based receiver at a location in North Italy. The storm, triggered by multiple solar flares and Earth-directed coronal mass ejections (CMEs), induced strong ionospheric disturbances, affecting GNSS signal propagation beyond equatorial and high-latitude regions. To investigate these effects, we recorded GNSS signals on L1 and L2 bands throughout the storm period, along with GNSS observation data from a nearby geodetic station. Our
analysis focuses on ionospheric irregularities using the Rate of TEC Index (ROTI) and scintillation indices. ROTI values revealed a significant increase in ionospheric turbulence during the storm’s main phase, coinciding with a Kp index of 9 and a Dst minimum of -335 nT. The recorded IQ samples were processed by using a software receiver, showing moderate amplitude scintillation on multiple GNSS satellites.
Furthermore, we show the effectiveness of the Software Defined Radio approach, to capture capture and reconstruct ionospheric disturbances with high fidelity for advanced post-processing of the events. The approach is validated by re-playing the recorded GNSS signals and processing the reproduced scenario by means of a commercial GNSS receiver and successfully reproducing scintillation indices
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
Effects of phase scintillation on the GNSS positioning error during the September 2017 storm at Svalbard
Full text linkIn early September 2017, several space weather events triggered disturbed conditions of the near‐Earth space. The combination of two coronal mass ejection arrivals, associated with an X‐class flare, caused a strong geomagnetic storm on 7 and 8 September, thus inducing diffuse ionospheric phase scintillations on Global Navigation Satellite System (GNSS) signals. This work analyzes the effects and the actual impact of such phase scintillations on transionospheric Global Positioning System (GPS) signals and on related positioning accuracy. The research focuses in particular on high‐latitude GPS L1 data, recorded during a test campaign in Svalbard, Norway. The joint effect of satellites at low elevation and the exposure of ionosphere to the geospace forcing make navigation a critical task for such a challenging environment. Data analysis shows that the performance of carrier smoothing algorithms was affected by the presence of moderate and strong phase scintillation. It is shown in this study that positioning errors double when GPS signals affected by scintillation are used. This work shows that scintillations induce a considerable clustering effect on the smoothed positioning solutions; therefore, a methodology to automatically and autonomously detect the boundaries of the scintillation event is suggested according to such an high‐level effect. The use of software‐defined radio receivers for automatically capturing and processing GNSS data affected by scintillation is an added value to the analysis, as it offers the possibility to implement advanced signal processing techniques and a deeper observation of the impact of scintillations on the signals
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