1,721,004 research outputs found
Visual Servoing on Image Maps
No full textIn this paper we consider the problem of servoing wheeled vehicles in an indoor, initially unknown environment. The proposed approach relies on a hybrid (metric and topological) map built on visual cues. Navigation is planned using topological information to trace a path through viapoints that can be robustly performed by visual servoing control to accurately reach the goal positions. A map of an unknown environment is built as acollection of images taken by an exploratory robot. Images represent nodes in a navigation graph, in which edges represent feasible paths that the robot can execute by visual servoing. Metric and topological information are stored in a hybrid map, which can be shared and cooperatively updated in real time by groups of robots. The merit of the proposed approach is to combine the accuracy of visual servoing methods with a reliable representation of an unknown environment. As a result, the method provides purely visual-based solutions to two of the most relevant problems involved respectively in the field of localization, that is the kidnapped robot problem, and in the field of mapping, that is the closed path detection problem. Experimental results on a laboratory setup are reported, showing the practicality of the proposed 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
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
Determinants of schedule-based transit performances in the city of Bologna
No full textIn this paper, the results of a research regarding the transit network of the city of Bologna are presented in order to highlight those factors affecting the reliability of a transit service at high frequency.
In literature, several authors relate bus service reliability to the variability of travel time performance (Polus, 1978; Sterman and Schofer, 1976); others with the adherence to schedules (Bates et al., 2001), others to the maintenance of the designed service frequency (Janos and Furth, 2002), others with the waiting time at the bus stops (Bowman and Turnquist, 1981), and others to the impossibility of getting on the bus because of capacity issues (Chapman, 1976).
Anyway, the reliability of a transit service is a key element both for users - real and potential ones - and providers. Low service reliability implies the reduction of the service quality perceived by users causing an increase of the amount of time passengers must wait at a bus stop as well as the comfort reduction due to vehicles’ overcrowding (Bates et al., 2001; Rietvield et al., 2001; TCRP, 1999; Prioni and Hensher, 2000; Welding, 1957; Turnquist, 1978). From providers perspective, low service reliability means a reduction of the veh-km delivered and an inefficient utilization of the fleet: some buses travels full of passengers whereas others are empty. This implies the need of additional vehicles to be provided, thus increasing the operating costs. Moreover, as reliability decrease, public transport demand will decrease too thus engendering a lower income for the service provider.
The reliability is strictly related to the bunching phenomenon. Bus bunching refers to a group of two or more transit vehicles scheduled to be evenly spaced along the same route, which run in the same location at the same time. This occurs when at least one of the vehicles is unable to keep its schedule because of the interaction with other vehicles of the traffic steam, presence of signalized intersections along the route, demand increase, etc., which implies a bus to be early/late with respect to the planned schedule.
Theoretically, the driver should try to adjust the bus speed in relation to the gap with the preceding bus; although it represents one of the most important hypothesis of bunching simulation models, this procedure, which requires driver knows the position of the preceding vehicles, is not usually adopted (Nagatani, 2001).
This research provides a general analysis based on reliability, identifying and discussing its determinants. The relative importance of each determinant is analyzed through a survey conducted along two of the main bus routes of the Bologna transit network. This analysis could allow providers identifying appropriate strategies, preventive or corrective ones, in order to improve the service reliability
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