1,721,029 research outputs found
Optimal band ratio analysis of worldview-3 imagery for bathymetry of shallow rivers (case study: Sarca river, Italy)
Full text linkThe Optimal Band Ratio Analysis (OBRA) could be considered as an efficient technique for bathymetry from optical imagery due to its robustness on substrate variability. This point receives more attention for very shallow rivers where different substrate types can contribute remarkably into total at-sensor radiance. The OBRA examines the total possible pairs of spectral bands in order to identify the optimal two-band ratio that its log transformation yields a strong linear relation with field measured water depths. This paper aims at investigating the effectiveness of additional spectral bands of newly launched WorldView-3 (WV-3) imagery in the visible and NIR spectrum through OBRA for retrieving water depths in shallow rivers. In this regard, the OBRA is performed on a WV-3 image as well as a GeoEye image of a small Alpine river in Italy. In-situ depths are gathered in two river reaches using a precise GPS device. In each testing scenario, 50% of the field data is used for calibration of the model and the remained as independent check points for accuracy assessment. In general, the effect of changes in water depth is highly pronounced in longer wavelengths (i.e. NIR) due to high and rapid absorption of light in this spectrum as long as it is not saturated. As the studied river is shallow, NIR portion of the spectrum has not been reduced so much not to reach the riverbed; making use of the observed radiance over this spectral range as denominator has shown a strong correlation through OBRA. More specifically, tightly focused channels of rededge, NIR-1 and NIR-2 provide a wealth of choices for OBRA rather than a single NIR band of conventional 4-band images (e.g. GeoEye). This advantage of WV-3 images is outstanding as well for choosing the optimal numerator of the ratio model. Coastal-blue and yellow bands of WV-3 are identified as proper numerators while only green band of the GeoEye image contributed to a reliable correlation of image derived values and field measured depths. According to the results, the additional and narrow spectral bands of WV-3 image lead to an average determination coefficient of 67% in two river segments, which is 10% higher than that of obtained from the 4-band GeoEye image. In addition, RMSEs of depth estimations are calculated as 4 cm and 6 cm respectively for WV-3 and GeoEye images, considering the optimal band ratio
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
Agronomic Comparisons of Heirloom and Modern Processing Tomato Genotypes Cultivated in Organic and Conventional Farming Systems
No full textThe yield and fruit quality of processing tomatoes (Solanum lycopersicum L.) have increased markedly over the past decades. The aim of this work was to assess the effects of the organic (OFS) and conventional farming systems (CFS) on the main agronomic parameters involved in processing tomato yield components and fruit quality traits of heirloom and modern genotypes. Marketable yield increased from heirloom to modern genotypes, both in OFS and in CFS, showing a difference of ≈20 t per hectare in favor of CFS. Total fruit yield (TY) was not improved from heirloom to modern assessed genotypes, and a difference of ≈35 t per hectare was observed in favor of CFS. In both farming systems, the highest marketable yield of modern genotypes was due to a higher number of fruits per plant, harvest index, nitrogen agronomic efficiency (NAE), and fruit water productivity. Moreover, the main growth parameters involved in the yield differences between OFS and CFS were the number of leaves per plant, the average fruit weight, the normalized difference vegetation index (NDVI), and NAE. It is noteworthy that fruit quality improvement in terms of color and brix per hectare was paralleled by a decrease of tomato pH in both farming systems. According to our results, we conclude that to reduce the current yield gap between OFS and CFS, agronomic and breeding efforts should be undertaken to increase leaf area index, fruit number per plant, and NAE for better genotype adaptation to organic farming systems
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
Il riflesso della cultura mediterranea nel mondo paremiologico italiano e spagnolo
No full textIn questo lavoro ci prefissiamo l’obiettivo di svelare alcuni aspetti della cultura mediterranea attraverso un approccio fraseologico e paremiologico, e riflettere su questi aspetti “segreti” di un mondo che ci è consueto per tanti altri motivi
A Web Processing Service for GNSS realistic planning
No full textThe spread presence of GNSS Permanent Station Networks makes satellite surveys simpler, quicker and cheaper, and the achievement of high precisions easier. However, the result of a GNSS campaign benefits from an accurate planning, especially in presence of natural or artificial obstructions that make satellite observations difficult. Most of the GNSS office suites provide planning tools to analyse the satellite's visibility; visibility plots, sky plots and DOP charts are commonly built from the GNSS almanac. They usually allow planning on single points, taking into account the obstructions due to terrain morphology or buildings by hand-drawing polar diagrams after a visit of each location to be surveyed. This task can be made fully automatic by using a digital surface model to build the obstruction plot and the almanac to evaluate satellites' positions, hence their visibility, in a GIS. The procedure may be applied to whole areas to find the best time for the survey campaign.
Taking a step further, this approach has been made available as a service by creating a Web Processing Service, which allows also non GIS specialists to access this tool through a simple webgis interface.
The user can select the satellites constellation, GPS and/or GLONASS, the cut-off elevation angle, the day, hour and temporal window of the survey. The service returns raster maps describing the minimum number of visible satellites and the PDOP index in every pixel. Moreover, the service implements some features of the UNAVCO TEQC software, which can help to choose the location of new permanent stations.
The implementation follows the OGC specifications and relies fully on FOSS software, combining different systems to provide the user web interface, the data storage and the processing engine.
The service features, the underlying technology and some examples will be presented in this paper
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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