1,720,965 research outputs found
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
Dynamic Positioning for ROV Operating in Fish Farms
No full textThe usages of Remotely Operated Unmanned Underwater Vehicles (ROVs') for inspection of marine structures is today an essential part of the offshore industry. However, in the case of inspection of fish farms, the ROV has to spend continuous time relatively close to the water surface, in exposed seas, while navigating irregular flexible fish nets. The ability for an ROV to effectively navigate within the fish farm cage and guarantee a complete inspection requires new tools, and dynamic positioning (DP) improvements. This thesis will use the simulation tool FHSim to investigate two aspects regarding these issues. First, it will examine, by simulations, the performance of different variations of a nonlinear observer and an extended kalman filter (EKF) with or without a cascaded current observer, in the ROV's operating conditions. Secondly a visualization tool is integrated with the ROV DP system that allows it to traverse the fish net autonomously while also visualizing its position in the cage. The visualization module also identifies net areas that have been inspected by the ROV. All the modified DP modules are assessed in several simulation cases designed to mimic ROV inspection behaviour. It was found that in particular, the nonlinear observer performed better in estimation and wave filtering abilities, while the EKF was superior in dead reckoning. These differences were attributed to the different nature of the two observers, their programmed integration method, and possibly insufficient tuning of the EKF. The autonomous net traversal algorithm was successfully able to make the ROV traverse the cage, however, some trajectory faults were identified. Improvements to overcome these faults were suggested
Feasibility Study on Active Wave Compensation of ROV - Modelling, Analysis and Simulation
No full textThe aquaculture industry is using remotely operated vehicles (ROVs) for maintenance tasks on fish farms. These tasks include, among others, washing of the netpen and visual inspections. These are tedious tasks, and it would be an advantage if the ROVs were controlled automatically instead of manually. Such systems exist in the industry today, but the systems are often designed to operate in deep water. In this thesis the focus lies with Salmon fish farms. These farms are today located at exposed areas to improve the growth environment for Salmon. Exposed locations require more robust maintenance systems as the locations itself are more prone to bad weather and large wave and current loads. When working in the wave zone, the large and highly varying first order wave loads are dominant. To be able to withstand these loads three small sized ROVs will be proposed and investigated. The ROVs are 600 kg, 200 kg and 50 kg.
The ROVs are analysed in Wadam to determine the kinetic properties of the designs. Dynamic positioning systems for the ROVs are suggested and time domain simulations are perfomed in SIMO. Weather data from Rataran fish farm is used to set up the simulation cases. Some alterations was necessary to use the results from Wadam in SIMO, as Wadam assumes surface vessels.
The results illustrate that an operational window for the three ROVs is set by a limiting significant wave height of 2.0 m and a peak period no less than 5 s should be operated in. However, and must be evaluated simultaneously. As some of the simulated cases illustrate, small significant wave heights or larger peak periods can also cause wave loads that are impossible to operate in
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
Dynamic Positioning for ROV Operating in Fish Farms
Full text linkThe usages of Remotely Operated Unmanned Underwater Vehicles (ROVs') for inspection of marine structures is today an essential part of the offshore industry. However, in the case of inspection of fish farms, the ROV has to spend continuous time relatively close to the water surface, in exposed seas, while navigating irregular flexible fish nets. The ability for an ROV to effectively navigate within the fish farm cage and guarantee a complete inspection requires new tools, and dynamic positioning (DP) improvements. This thesis will use the simulation tool FHSim to investigate two aspects regarding these issues. First, it will examine, by simulations, the performance of different variations of a nonlinear observer and an extended kalman filter (EKF) with or without a cascaded current observer, in the ROV's operating conditions. Secondly a visualization tool is integrated with the ROV DP system that allows it to traverse the fish net autonomously while also visualizing its position in the cage. The visualization module also identifies net areas that have been inspected by the ROV. All the modified DP modules are assessed in several simulation cases designed to mimic ROV inspection behaviour. It was found that in particular, the nonlinear observer performed better in estimation and wave filtering abilities, while the EKF was superior in dead reckoning. These differences were attributed to the different nature of the two observers, their programmed integration method, and possibly insufficient tuning of the EKF. The autonomous net traversal algorithm was successfully able to make the ROV traverse the cage, however, some trajectory faults were identified. Improvements to overcome these faults were suggested
Feasibility Study on Active Wave Compensation of ROV - Modelling, Analysis and Simulation
Full text linkThe aquaculture industry is using remotely operated vehicles (ROVs) for maintenance tasks on fish farms. These tasks include, among others, washing of the netpen and visual inspections. These are tedious tasks, and it would be an advantage if the ROVs were controlled automatically instead of manually. Such systems exist in the industry today, but the systems are often designed to operate in deep water. In this thesis the focus lies with Salmon fish farms. These farms are today located at exposed areas to improve the growth environment for Salmon. Exposed locations require more robust maintenance systems as the locations itself are more prone to bad weather and large wave and current loads. When working in the wave zone, the large and highly varying first order wave loads are dominant. To be able to withstand these loads three small sized ROVs will be proposed and investigated. The ROVs are 600 kg, 200 kg and 50 kg.
The ROVs are analysed in Wadam to determine the kinetic properties of the designs. Dynamic positioning systems for the ROVs are suggested and time domain simulations are perfomed in SIMO. Weather data from Rataran fish farm is used to set up the simulation cases. Some alterations was necessary to use the results from Wadam in SIMO, as Wadam assumes surface vessels.
The results illustrate that an operational window for the three ROVs is set by a limiting significant wave height of 2.0 m and a peak period no less than 5 s should be operated in. However, and must be evaluated simultaneously. As some of the simulated cases illustrate, small significant wave heights or larger peak periods can also cause wave loads that are impossible to operate in
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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