1,720,958 research outputs found
Procedures and technologies for 3D reconstruction with divers of underwater archaeological sites and marine protected areas
No full textUnderwater monitoring and exploration actions are fundamental to preserve natural habitats and submerged cultural heritage, but researchers have to face high costs related to technology and staff to carry out researches in this troublesome environment. As a partial solution to these problems, Citizen Science has been incrementally employed by the scientific community but, to effectively make the most of it, it is mandatory to design two components: a generic-scenario procedure that describes the steps to perform before, during and after the survey and tailored technologies to acquire, gather, process and visualize the environmental data. In this work, a procedure tested in different underwater missions, that is the enhancement of a precedent one, and technologies that, arranged in a pipeline, carry out all the process from data acquisition to output visualization are presented. The procedure and technology were tested in tailored tests aimed to guarantee the validity of the technologies
DocuScooter: A novel robotics platform for marine citizen science
No full textConservation and monitoring of marine systems and large-scale underwater data acquisition are too demanding for single researchers. The exploitation of citizen science and the development of new technology can significantly facilitate these actions. In this work a novel system that allows scuba divers to collect data during their leisure activity is presented. It consists of a modular robotics system connected with a variable number of heterogeneous payloads, directly manageable through a tablet, to equip an underwater scooter. After the mission, the user can upload the data on an appropriate web server and launch a 3D reconstruction process, providing ad-hoc outputs for different applications. Copyright © 2017 by the International Society of Offshore and Polar Engineers (ISOPE)
Underwater position estimation for an underwater vehicle using unscented Kalman filter
No full textMarine researchers need consistent historical and georeferenced data from the marine environment in order to constantly monitor the biological condition of the habitat or to document delicate archeological sites. To overcome the difficulties related to the acquisition of high quantity of worthy data and to the accurate estimation of the position, the development of easy to-use IT tools could certainly help. This article aims to present a tool that can equip different type of underwater vehicles capable of estimating its position during his surveys using its on-board sensors and with the aid of an external buoy. The estimation algorithm is based on the UKF technique and some preliminary simulation results of its performances are presented
Design and Validation of a Breathing Detection System for Scuba Divers
No full textDrowning is the major cause of death in self-contained underwater breathing apparatus (SCUBA) diving. This study proposes an embedded system with a live and light-weight algorithm which detects the breathing of divers through the analysis of the intermediate pressure (IP) signal of the SCUBA regulator. A system composed mainly of two pressure sensors and a low-power microcontroller was designed and programmed to record the pressure sensors signals and provide alarms in absence of breathing. An algorithm was developed to analyze the signals and identify inhalation events of the diver. A waterproof case was built to accommodate the system and was tested up to a depth of 25 m in a pressure chamber. To validate the system in the real environment, a series of dives with two different types of workload requiring different ranges of breathing frequencies were planned. Eight professional SCUBA divers volunteered to dive with the system to collect their IP data in order to participate to validation trials. The subjects underwent two dives, each of 52 min on average and a maximum depth of 7 m. The algorithm was optimized for the collected dataset and proved a sensitivity of inhalation detection of 97.5% and a total number of 275 false positives (FP) over a total recording time of 13.9 h. The detection algorithm presents a maximum delay of 5.2 s and requires only 800 bytes of random-access memory (RAM). The results were compared against the analysis of video records of the dives by two blinded observers and proved a sensitivity of 97.6% on the data set. The design includes a buzzer to provide audible alarms to accompanying dive buddies which will be triggered in case of degraded health conditions such as near drowning (absence of breathing), hyperventilation (breathing frequency too high) and skip-breathing (breathing frequency too low) measured by the improper breathing frequency. The system also measures the IP at rest before the dive and indicates with flashing light-emitting diodes and audible alarm the regulator malfunctions due to high or low IP that may cause fatal accidents during the dive by preventing natural breathing. It is also planned to relay the alarm signal to underwater and surface rescue authorities by means of acoustic communication
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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