1,720,979 research outputs found
Off-Road Path and Obstacle Detection Using Decision Networks and Stereo Vision
No full textAutonomous driving in off-road environments requires
an exceptionally capable sensor system, particularly given
that the unstructured environment does not provide many of the
cues available in on-road environments. This paper presents a
complex vision system, which is able to provide the two basic
sensorial capabilities needed by autonomous vehicle navigation in
extreme environments: obstacle detection and path detection. A
variable-width-baseline (up to 1.5 m) single-frame stereo system
is used for pitch estimation and obstacle detection, whereas a
decision-network approach is used to detect the drivable path by a
monocular vision system. The system has been field tested on the
TerraMax vehicle, which is one of the only five vehicles to complete the 2005 Defense Advanced Research Projects Agency (DARPA) Grand Challenge course
An agent based evolutionary approach to path detection for off-road vehicle guidance
No full textThis paper describes an ant colony optimization approach adopted to decide on road-borders to automatically guide a vehicle developed for the DARPA Grand Challenge 2004. Due to the complexity of off-road trails and different natural bound-aries of the trails, lane markers detection schemes cannot work. Hence border detec-tion is based on Ant Colony Optimization technique. Two borders at two sides of the road (as seen by a camera fixed on the vehicle) are tracked by two agent colonies: agents ’ moves are inspired by the behaviors of biological ants when trying to find the shortest path from nest to food. Reinforcement learning is done by pheromone updating based on some heuristic function and by changing the heuristic balancing parameters with the experience over the last tracked results. Shadow removal has also been introduced to increase robustness. Results on different off-road environments, as provided in the DARPA Grand Challenge 2004, have been shown in the form of correct detections, false positives and false negatives and their dependence on number of ant-agents and balancing edge exploitation and pheromone-exploitation. Key words: Ant Colony Optimization, automatic off-road vehicle guidance, evolutionary algorithms, intelligent vehicles.
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
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