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Optimisation of inversion methods for near-surface current measurements in regions with strong horizontal shear
Full text linkHavprosessene som finner sted i sjiktet nær overflaten er en av nøkkelfaktorene i klimasystemet, og egnede metoder for å måle strømninger i den øvre delen av vannsøylen er nødvendig for å forstå mønstrer og drivkrefter. Bruk av inversjonsmetoder for å måle strømningshastighet gjør det mulig å bruke fjernmåling, og har potensial til å kartlegge strømninger over flere km^2. Inversjonsmetoder kan enten kan måle overflatehastighet eller en dybdeavhengig strømningsprofil. Hastigheter blir avledet ved å analysere bølgespredningen innenfor definerte romlige vinduer. Størrelsen og plasseringen av disse vinduene bestemmer den horisontale og vertikale oppløsningen til strømningsprofilene. Formålet med denne oppgaven er å undersøke om det finnes en optimal vindusstørrelse for å fange opp horisontalt skjær og vertikal skjær, og om det finnes en vindusstørrelse som lykkes i å fange opp begge deler. Målinger av bølgeoverflaten ble utført med Free Surface-Synthetic Schlieren og strømningshastigheten ble beregnet med tre inversjonsmetoder. Effective Depth Method gir en lineær, dybeavhengig strømningsprofil, Polynomial Effective Depth Method gir en polynomisk dybdeavhengig strømningsprofil og den siste metoden måler strømningshastigheten nær overflaten. Tre alternativer for vindusplassering ble undersøkt, og de beregnede strømningshastighetene ble evaluert opp mot hastighetsmålinger utført med Particle Image Velocimetry. Studien viser at høy horisontal oppløsning oppnås for små, tett plasserte vinduer, mens høy vertikal oppløsning og stort rekkevidde på dybden oppnås ved å analysere bølgedispersjonen i store vinduer. Det ble identifisert et lite utvalg av vindusstørrelser som ga et godt kompromiss mellom behovene til horisontal og vertikal oppløsning. For disse vindusstørrelsene kan både overflate- og dybdeoppløsningen utledes med relativt lave kvadratisk gjennomsnitts-feil. Resultatene viser hvordan vindusstørrelse og vindusavstand kan justeres i områder med sterkt horisontalt skjær for å optimalisere den horisontale og vertikale nøyaktigheten.Upper-ocean processes are one of the key factors in the climate system, and suitable methods for measuring currents in the upper part of the water column is needed to understand the patterns and driving forces. Current measurements using inversion methods enables the use of remote sensing and has the potential to map currents over multiple km^2. Inversion methods can measure either the surface current or a depth-dependent current profile. Velocities are derived by analysing the wave dispersion within defined spatial windows. The size and placement of these windows determine the horizontal and vertical resolution of the current profiles. The purpose of this thesis is to explore whether there is an optimal window size for capturing horizontal shear and vertical shear, and whether there is a window size that successfully captures both. Measurements of the wave surface were performed with Free Surface-Synthetic Schlieren and the current velocity calculated with three inversion methods. The Effective Depth Method derives a linear, depth-dependent velocity, the Polynomial Effective Depth Method derives a polynomial current profile and the last method derives the near-surface current velocity. Three options for window placement were explored and the calculated currents were evaluated with Particle Image Velocimetry used as truth measurement. The study shows that high horizontal resolution is achieved for small and closely spaced windows, whereas high vertical resolution and large depth-range is achieved by analysing the wave dispersion in large windows. A small range of window sizes that provided a good compromise between the needs of horizontal and vertical resolution was identified. For these window sizes both the surface and depth resolution could be derived with relatively low Root-Mean-Square errors. The results demonstrate how the window size and window spacing can be adjusted in regions of strong horizontal shear in order to optimise the horizontal and vertical accuracy
Optimisation of inversion methods for near-surface current measurements in regions with strong horizontal shear
No full textHavprosessene som finner sted i sjiktet nær overflaten er en av nøkkelfaktorene i klimasystemet, og egnede metoder for å måle strømninger i den øvre delen av vannsøylen er nødvendig for å forstå mønstrer og drivkrefter. Bruk av inversjonsmetoder for å måle strømningshastighet gjør det mulig å bruke fjernmåling, og har potensial til å kartlegge strømninger over flere km^2. Inversjonsmetoder kan enten kan måle overflatehastighet eller en dybdeavhengig strømningsprofil. Hastigheter blir avledet ved å analysere bølgespredningen innenfor definerte romlige vinduer. Størrelsen og plasseringen av disse vinduene bestemmer den horisontale og vertikale oppløsningen til strømningsprofilene. Formålet med denne oppgaven er å undersøke om det finnes en optimal vindusstørrelse for å fange opp horisontalt skjær og vertikal skjær, og om det finnes en vindusstørrelse som lykkes i å fange opp begge deler. Målinger av bølgeoverflaten ble utført med Free Surface-Synthetic Schlieren og strømningshastigheten ble beregnet med tre inversjonsmetoder. Effective Depth Method gir en lineær, dybeavhengig strømningsprofil, Polynomial Effective Depth Method gir en polynomisk dybdeavhengig strømningsprofil og den siste metoden måler strømningshastigheten nær overflaten. Tre alternativer for vindusplassering ble undersøkt, og de beregnede strømningshastighetene ble evaluert opp mot hastighetsmålinger utført med Particle Image Velocimetry. Studien viser at høy horisontal oppløsning oppnås for små, tett plasserte vinduer, mens høy vertikal oppløsning og stort rekkevidde på dybden oppnås ved å analysere bølgedispersjonen i store vinduer. Det ble identifisert et lite utvalg av vindusstørrelser som ga et godt kompromiss mellom behovene til horisontal og vertikal oppløsning. For disse vindusstørrelsene kan både overflate- og dybdeoppløsningen utledes med relativt lave kvadratisk gjennomsnitts-feil. Resultatene viser hvordan vindusstørrelse og vindusavstand kan justeres i områder med sterkt horisontalt skjær for å optimalisere den horisontale og vertikale nøyaktigheten
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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