1,720,960 research outputs found
Validation of near infrared satellite based algorithms to retrieve atmospheric water vapour content over land
No full textThis paper presents the validation results of ENVISAT MERIS and TERRA MODIS retrieval algorithms for atmospheric Water Vapour Content (WVC) estimation in clear sky condition on land. The MERIS algorithm exploits the radiance ratio of the absorbing channel at 900 nm with the almost absorption-free reference at 890 nm, while the MODIS one is based on the ratio of measurements centred at near 0.905, 0.936, and 0.94 mu m with atmospheric window reflectance at 0.865 and 1.24 mu m. The first test was performed in the Mediterranean area using WVC provided from both ECMWF and AERON-ET. As a second step, the performances of the algorithms were tested exploiting WVC computed from radiosoundings (RAOBs) in the North East Australia. The different comparisons with respect to reference WVC values showed an overestimation of WVC by MODIS (root mean square error percentage greater than 20%) and an acceptable performance of MERIS algorithms (root mean square error percentage around 10%)
Telerilevamento da satellite di eventi precipitativi: analisi sul bacino del Trasimeno
No full textPrevedere e monitorare la distribuzione spaziale e temporale della pioggia è uno dei principali obiettivi della meteorologia e della diagnostica ambientale e il telerilevamento con sensori posti su satellite è sicuramente in grado di fornire un aiuto fondamentale. Il modo classico per ricavare la precipitazione da misure satellitari è basato su osservazioni da sensori a microonde, ma ultimamente si stanno utilizzando anche dati nell’infrarosso termico per stimare gli eventi precipitativi, dati in grado di fornire una migliore risoluzione spaziale e temporale. Sfruttando la disponibilità di un ampio data set di misure satellitari, sono state prodotte delle mappe di pioggia sul bacino del Trasimeno che sono state validate con dati di pioggia registrati da stazioni a terra.
I dati da satellite, ossia le temperature di brillanza a microonde fornite dal sensore AMSU e AMSR/E su satellite AQUA e le radianze nell’infrarosso termico fornite dal sensore MODIS sempre su satellite AQUA, sono stati elaborati con algoritmi di tipo statistico, noti in letteratura. Nel caso delle misure a microonde vengono fornite direttamente stime di intensità di precipitazione, mentre nel caso delle misure ad infrarosso viene analizzata la soglia che permette di rintracciare un evento precipitativo.
Gli algoritmi sono stati implementati in ambiente Matlab, realizzando una procedura automatica che permette di mappare i parametri geofisici ottenuti nella zona geografica di interesse.
I risultati relativi alla individuazione dell’evento piovoso e alla stima della intensità di precipitazione da misure da satellite sono stati prima ottenuti su tutta l’area del Mediterraneo, per effettuare confronti incrociati tra i vari sensori satellitari e i vari algoritmi noti in letteratura, per poterne valutare le prestazioni. Poi tali risultati sono stati confrontati con i contemporanei dati di pioggia forniti dai pluviometri del bacino del Trasimeno ottenendo risultati assai promettenti
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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