1,720,963 research outputs found
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
Grid-search applications for trajectory design in presence of flyby
No full textNella fase di progettazione di una missione di esplorazione dello spazio profondo, si possono distinguere due fasi: un trasferimento interplanetario e un fase finale nel sistema di lune orbitanti il pianeta considerato. In entrambi i casi, la fionda gravitazionale incide positivamente sul costo complessivo e sulla ricerca scientifica condotta della missione.Questa tesi di dottorato si concentra su metodi, tecniche e strumenti per modellare la traiettoria in presenza di flyby. A seconda del modello gravitazionale utilizzato e dello scenario di missione previsto, è possibile analizzare varie parti del search-space e ricavare diverse intuizioni sulla natura dell’interazione col terzo corpo. La capacità di un metodo di rivelare intuizioni sulla dinamica dipende dalla scelta dei parametri di performance e delle variabili di controllo utilizzate per studiare l’evoluzione della traiettoria sotto l’effetto della dinamica. L’ottimizzazione è un passo necessario per confermare/confutare un disegno preliminare dell’orbita, ricavato in una dinamica approssimata, valutando la sua bontà in uno ad alta fedeltà. Mentre, in generale, il processo di inferenza è deduttivo e si sposta dal modello ai dati, in condizioni specifiche, il flusso induttivo può essere seguito. La migliorata comprensione della dinamica può influenzare positivamente il processo di disegno dell’orbita. Le petal rotations sono un esempio lampante di modello derivato in una dinamica approssimata (patched conics), confermato poi dall’ottimizzazione e solo successivamente identificato come orbita periodica. La sequenza Crank-Over-Top, al contrario, è l’esempio di un modello non adatto. Questo lavoro si occupa di metodi di ricerca a griglia per l’identificazione di flyby attuabili. Il filo conduttore della dissertazione riguarda la riduzione dello sforzo di calcolo associato alla scansione del search-space. Presentiamo una soluzione a tre fasi: la ricombinazione dei search-spaces associati alle traiettorie di precedenti e successive al passaggio ravvicinato, il passaggio da una parametrizzazione temporale del search-space ad una formulazione in elementi orbitali e l’implementazione di tecniche di pruning, basate su regioni di delimitazione definite dal delta-v e dalla variazione di elementi orbitali derivata per caso limite del flyby. Seguendo questa logica, la 3D Flyby map è stata sviluppata per studiare il flyby nella dinamica dei tre corpi, per confrontare le differenze rispetto alla modellazione patched conics dell’effetto del flyby e per progettare sequenze di flyby risonanti per il tour Europa Clipper. Il diverso effetto di flybys diretti e retrogradi sulla traiettoria successiva al passaggio ravvicinato e la maggiore efficienza dei primi rispetto ai secondi rappresentano le riflessioni più significative.In the design process of a deep-space exploration mission, two phases can be distinguished: an interplanetary cruise and a final phase in planetary moon-system. In both cases the flyby manoeuvres have a positive impact on the overall mission cost and the scientific return.
This doctoral dissertation focuses on methods, techniques, and tools for modeling the trajectory in presence of flybys. Depending on the gravitational model used and the mission scenario foreseen, various part of the search space can be analysed and different insights derived about the nature of the third-body interaction. The ability of one method to reveal insights on the dynamics depends on the choice of the performance parameters and control variables used to study the trajectory evolution under the effect of the dynamics. Optimisation is a necessary step to confirm/disprove the solution proposed in the preliminary design, derived in simpler dynamics, by evaluating its applicability in the full-body one. While, generally, the inference process is deductive and moves from the model to the data, under specific conditions, the inductive stream can be followed. The improved understanding of the dynamics might positively affect the design process. Petal rotations are a clear example of a technique derived in patched conics, confirmed by the optimisation and later identified into periodic orbits. Crank-Over-Top sequence the one of a not proper modelling.
This work deals with grid-search approaches for the identification of feasible flyby. The main theme encompassing the dissertation regards the reduction of the computational effort associated to the scanning of the search space. We present a three-steps solution: recombining the search spaces associated to the pre- and post-encounter trajectories, switching from an epoch-based parametrisation of the search space to an orbital elements formulation and implementing pruning techniques, based on bounding regions defined by delta-v levels and orbital elements variations derived for limiting cases of the flyby. Following this logic, the 3D Flyby map is developed to study flyby in the three-body dynamics, to compare difference in the patched conics modelling of the flyby effect, and to design the sequence of resonant flybys for Europa Clipper tour. The different effect of direct and retrograde flybys on the post-encounter trajectory and the higher efficiency of the former represent the most significant observations.DIPARTIMENTO DI SCIENZE E TECNOLOGIE AEROSPAZIALI32BIGGS, JAMES DOUGLASMASARATI, PIERANGEL
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