1,720,957 research outputs found
Enhanced Altitude Estimation for Unmanned Aerial Vehicles in a GNSS-denied Environment
No full textGNSS-denied environments represent challenging environments for autonomous drones. Ensuring an accurate altitude estimate plays a crucial role in guaranteeing mission efficiency in such scenarios. The literature on autonomous drone localization in GNSS-denied environments relies on visual inertial odometry-based algorithms. However, the reliability of this technology cannot be guaranteed in poor features environments (homogeneous floor, white walls) or in high and low brightness conditions. Even applications adopting loop closure algorithms in combination with visual inertial odometry localization suffer from considerable position estimation drift in challenging environments. This paper aims to propose a methodology to address the altitude estimation problem for drones operating in GNSS-denied environments by combining a V-SLAM algorithm with altitude measurements from a range finder. To account for ground inconsistencies due to varying terrain or obstacles, we have developed an Adaptive Kalman Filter. The Mahalanobis distance evaluation accomplishes the task of detecting these inconsistencies, enabling the filter to adapt and update states properly even in the presence of inconsistent range finder measurements. Experimental results demonstrate the effectiveness of the proposed solution in mitigating the drift accumulated by a purely V-SLAM algorithm
Enhancing Visual–Inertial Odometry Robustness and Accuracy in Challenging Environments
Full text linkVisual–Inertial Odometry (VIO) algorithms are widely adopted for autonomous drone navigation in GNSS-denied environments. However, conventional monocular and stereo VIO setups often lack robustness under challenging environmental conditions or during aggressive maneuvers, due to the sensitivity of visual information to lighting, texture, and motion blur. In this work, we enhance an existing open-source VIO algorithm to improve both the robustness and accuracy of the pose estimation. First, we integrate an IMU-based motion prediction module to improve feature tracking across frames, particularly during high-speed movements. Second, we extend the algorithm to support a multi-camera setup, which significantly improves tracking performance in low-texture environments. Finally, to reduce the computational complexity, we introduce an adaptive feature selection strategy that dynamically adjusts the detection thresholds according to the number of detected features. Experimental results validate the proposed approaches, demonstrating notable improvements in both accuracy and robustness across a range of challenging scenarios
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
Autonomous Drones in GNSS-Denied Environments: Results from the Leonardo Drone Contest
Full text linkThe Leonardo Drone Contest is an autonomous drone competition that aims at finding innovative solutions for drones operating in a Global Navigation Satellite System (GNSS) denied environment. At the end of a three years cycle of the competition, in this paper a review of the identified system and conclusions made by the DRAFT team from Politecnico di Torino is presented. The authors aim at introducing the final solutions to the challenge in terms of hardware components, algorithms and development process. The proposed approach has been widely tested and validated, and it ranked second in the competition. The well-consolidated procedure, resulting from many iterations in the development cycle, has contributed
to further improvements during the three-year challenge and can be helpful for anyone who desires to approach the problem of autonomous drones employed in smart cities contexts
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