1,720,971 research outputs found
Glacier Monitoring with Dual-Receiver Radar Architecture: Preliminary Experimental Results
No full textGlaciers are nowadays becoming a more and more important topic to investigate, due to their close relationship with the climate change and impact on people living in mountainous areas. For this reason, the researches on new, faster, non-destructive and valuable techniques to monitor such natural bodies became necessary. In this framework, an already-existed radar dual-receiver architecture, used in recent years for snowpack monitoring, has been tailored to be used for the first time for glacier monitoring. After some improvements of the system, the radar architecture was tested in the Italian Alps, more precisely at the Cherillon glacier (Valle d'Aosta). The preliminary results show a good agreement with the traces collected by a Ground Penetrating Radar (GPR) in 2019 for what concerns glacier depth, when a speed for the wave in the ice is assumed. However, the dual-receiver architecture demonstrated that it was capable of estimating independently not only the glacier depth, but also the wave speed, opening in addition the analysis to further possibilities
A Novel PIFA Antennas Design With Capacitive Load for Glacier Monitoring Applications
No full textIn glaciology, Ground Penetrating Radar (GPR) are frequently used to characterize electrical and physical properties of glaciers and snow coverages. An application is the estimation of the snow water equivalent of glaciers, coming from the knowledge of internal features of the glacier itself, such as its depth and density. For glacier monitoring, the usual frequencies space from few MHz to hundreds of MHz. Depending on the compromise between the penetration depth and the spatial resolution, the working frequency was determined. In this work, we designed, developed and measured a 300 MHz antenna used for this purpose. The shape and size were modeled in order to be used in portable systems; therefore, it was important to have light and small radiators. For this reason, we implement a novel planar inverted-F antenna (PIFA) design with capacitive load, reaching small dimensions compared to the wavelength
Mixed Analytical-Numerical Modeling of Radar Backscattering for Seasonal Snowpacks
No full textThe intensity of the backscattered signal collected by active radars over wet, seasonal snowpacks depends on numerous variables related to the snowpack, which are often difficult to determine accurately. In recent years, thanks to the increased availability of spaceborne synthetic aperture radars (SARs), a temporal relationship between wet-snow metamorphism and microwave backscattering has been demonstrated. However, a precise quantitative description of this phenomenon has yet to be fully determined. In this article, we propose a new mixed analytical-numerical model to describe the effect of the physical parameters related to the wet snowpack metamorphism on the intensity of the backscattering at L, C, and X bands, with a focus on high alpine snowpacks. Particular attention was paid to integrate the effects of the snow superficial roughness and the snow scattering. The model is first applied to several simulated snowpacks and then validated against a real multitemporal SAR signature acquired by Sentinel-1 over the snow station of Malga Fadner (South Tyrol, Italy) and of Torgnon (Aosta Valley, Italy). The comparison between the model outcomes and the satellite data were in good agreement, leading to the possibility of using such method for operational identification of the run-off phase from remote locations
Seasonal Snow Melting Process Investigation in Polar Environment Using a Dual-Receiver Radar Architecture
No full textDielectric Characterization of Snow at 24 GHZ: Insights from a Low-Cost Radar in Sodankyla, Finland
No full textMonitoring the internal structure of the snowpack is imperative for managing snow-related hazards like avalanches and snowmelt floods. The surge in availability of cost-effective, low-power, and low-profile 24 GHz frequency-modulated continuous-wave (FMCW) radars, originally designed for the automotive sector, has opened new possibilities. This paper illustrates the application of a compact and economical FMCW radar to enhance snowpack studies by swiftly providing the dielectric properties of snow and potentially assessing density and liquid water content (LWC). The radar functions as a snowpit instrument, creating expedited snow profiles of dielectric properties, aiming to overcome the drawbacks of slower, operator-dependent traditional density cutters. Initial results showcase the real part of the relative dielectric permittivity in actual snow conditions. Results are compared with manual measurements directly taken in the snowpit and with the bulk measurements taken with a well-established multi-band radar
Monitoring Wet Snow with a Dual-Receiver Radar Architecture: Preliminary Experimental Results
No full textIn the latest years the role of the cryosphere in our daily life has been of growing interest. The climate change rules the process of melting and the snow has become a crucial water storage to be monitored. In particular, the monitoring of slightly or moderately wet snow is nowadays a significant challenge under different perspectives. In this paper, preliminary results from an experimental test carried out during spring 2022 using a portable microwave radar are shown, highlighting the capability of that instrument to monitor wet snowpacks. Here, a comparison between radar and manual data is reported. Even if more analysis has to be carried out in the future, the preliminary results show a general agreement
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
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