1,720,960 research outputs found
An Entropy-Like Approach to Vision-Aided Inertial Navigation
No full textThe paper presents a loosely coupled approach for the improvement of the state estimation in autonomous inertial navigation tasks, augmented via image-based relative motion estimation. The proposed approach uses a novel Pose Estimation technique based on the minimization of a Entropy-Like cost function which is robust by nature to the presence of noise and outliers in the visual features. A Indirect Kalman Navigation Filter is used, in the framework of stochastic cloning. The robust relative pose estimation given by our novel technique is used to feed a relative position fix to the navigation filter. Simulations results are presented and compared with the results obtained via the classical Iterative Closest Point approach
Computerized casts for Orthodontic purpose using powder-free intraoral scanners: accuracy, execution time and patient feedback.
Full text linkIntroduction. Intraoral scanners allow direct images of oral situation, with fewer steps than conventional impressions.The purpose
of this study was to compare the accuracy of digital impressions, traditional impressions, and digitalization of full-arch gypsum
models, to evaluate timing of differentmethods and finally to study perception of patients about conventional and digital impression
techniques. Methods. Dental arches of fourteen patients were evaluated by alginate impression, titanium dioxide powder-free
intraoral scanning (Trios, 3Shape), and digitalization obtained from gypsum models using the same scanner. Conventional and
digital techniqueswere evaluated throughmeasurements (lower and upper arch anteroposterior length, lower and upper intercanine
distance, and lower and upper intermolar distance) with a caliber for analogic models and using a computer software for digital
models (Ortho Analyzer, Great Lakes Orthodontics). In addition, chairside and processing times were recorded. Finally, each
patient completed a VAS questionnaire to evaluate comfort. Statistical analyses were performed with ANOVA and Tukey tests
for accuracy measurements and paired -test for times and VAS scores. Significance was predetermined at < 0.05. Results. The
measurements obtained with intraoral scanning, gypsum models after conventional impression, and digitalized gypsum models
were not significantly different. Both chairside and processing times of digital scanning were shorter than the traditional method.
VAS reporting patients comfort were significantly higher when evaluating digital impression. Conclusions. Intraoral scanners used
for orthodontic applications provide useful data in clinical practice, comparable to conventional impression. This technology is
more time efficient than traditional impression and comfortable for patients. Further evolution with more accurate and faster
scanners could in future replace traditional impression methods
An Entropy-Like Approach to Vision based Autonomous Navigation
No full textThis article proposes a novel solution to the Pose Estimation problem for Ego–Motion from stereo camera images. The approach uses a nonlinear function, derived from the concept of Gibbs’ Entropy, which is robust by nature to the presence of noise and outliers in the visual features. The SIFT algorithm is used to collect and match the features from stereo images. The 3–vectors quaternion parameterization is used to parameterize the rotation matrix, in order to avoid the unit norm constraint in the minimization computation. Simulations and experimental results are presented and compared with the results obtained via the classical Iterative Closest Point approach
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
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