1,721,101 research outputs found
Pilot Model Development and Human Manual Control Considerations for Helicopter Hover Displays
Full text linkHead-down hover displays and instrument panels theoretically provide all necessary 2ight data information to control low-speed helicopter manoeuvring. However, past experiments have shown that head-down displays can incur high workload, control instability, and even loss of control when used as the sole 2ight data source. This paper investigates the reasons for this instability incurred by replacing good outside visuals with a head-down hover display and an instrument panel. A pilot model based on crossover theory is developed for a linear six-degree-of-freedom Bo. helicopter model. Utilising a target trajectory based on-theory and assuming perfect information availability, the developed model can perform the required manoeuvring task with a control time-delay stability margin of . s (with SAS) or . s (without SAS). Then, the actual information availability based on human perception methods and limitations is discussed. A pilot-in-the-loop experiment in the SIMONA Research Simulator qualitatively validates the developed pilot model for good outside visuals. However, the pilot model does not capture the added diZculties of having to utilise the hover display and instrument panel instead of good outside visuals; during the experiment, the task was impossible to complete with only these displays. This is likely caused by an increase in control time-delay, which in turn is caused by the loss of peripheral and flow 1eld information, a more abstract information representation compared to good outside visuals, and the fact that the pilot now needs to scan multiple displays to acquire all necessary 2ight state information. Improving head-down hover display symbology and scaling factors might rectify some, but probably not all of these effects.Control & Simulatio
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
Development of Vessel Connectors for Coronary Bypass Surgery
No full textMechanical Maritime and Materials Engineerin
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
Aviate, Navigate: Functional Visualizations of Asymmetric Flight Envelope Limits
No full textCurrent aircraft flight deck interfaces do not provide information on how a performance-altering failure constrains the aircraft's flight envelope. As a result, it is difficult for flight crews to plan an emergency landing trajectory. This study presents the results of the conceptual development of novel constraint-based interface symbology that aims to solve this issue. As no fully functional on-line flight envelope prediction system implementations currently exist, a simplified dynamical model with an asymmetric flight envelope was developed to overcome this limitation. The proposed interface symbology integrates with the existing primary flight display and navigation display. A human-in-the-loop experiment was conducted to validate the effectiveness of the used symbology. The results lend credibility to the belief that presenting flight envelope constraints in terms of reachable navigation states may improve short-term tactical planning and reduce the pilot's mental workload during emergency situations.Aerospace EngineeringControl & Operation
Increasing Acceptance of Tactile Feedback in UAV Teleoperations by Visualizing Force Fields
No full textDue to the increasing complexity of controlling Unmanned Aerial Vehicles (UAVs), researchers have been trying to let automation take part of the UAV control in order to eliminate human error and reduce the workload of the operator. Such a system has been developed for UAV teleoperators which incorporates haptic feedback on the control stick based on a Collision Avoidance System (CAS). When nearing obstacles, the operator gets redirected by the haptic feedback and so avoiding a possible collision. However from previous and similar studies it was stated that haptic interfaces have a low user acceptance due to the limited knowledge and insight of the pilots on the automation. To improve the acceptance of the haptic feedback system this research adds additional visualizations to an existing interface. In order to evaluate these newly designed visuals, a human-in-the-loop experiment was performed. Results show that there were no significant differences between the different configurations, however, acceptance questionnaires filled in by the participants revealed that they preferred operating an UAV with additional visualizations. This means that raising the acceptance of the haptic interface was accomplished without deterioration of the operators safety, performance and workload.Aerospace EngineeringControl & OperationsATM, Airports and Safet
Effect of Automation Transparency on Acceptance of Resolution Advisories in Air Traffic Control
No full textAs air traffic controller workload is a bottleneck on air traffic growth, automation solutions have been proposed. This study investigates the effect of transparency on the acceptance of resolution advisories generated by an adaptive automation tool and the frustration experienced by controllers when using this tool. Two different kinds of transparency were looked at. The first shows the variables the automation uses directly, while the second shows them only indirectly. Both incorporated a preview functionality, which allowed for comparison of the resolution advisory and the controller solution when the automation activated. A human in the loop experiment featuring these different kinds of transparency was performed. The results show that there is no significant difference in acceptance of advisories, workload or frustration ratings obtained from the NASA-TLX between the different levels of transparency. However, the group using the direct form of transparency received more short-term collision alerts and the time that the automation was active was higher than for the group using the indirect transparency. No significant difference in controller trust in the automation was found. In conclusion, there does not appear to be an influence of transparency on controller acceptance of resolution advisories, controller workload, controller frustration or controller trust in the automation. However, the experimenter noticed that most participants in the experiment did not use the information from the preview functionality to compare their solution to the resolution advisory. As they did not use the automation transparency to its full potential, further research on automation transparency is recommended in order to either confirm or dismiss the findings of this study.Aerospace EngineeringControl & Operation
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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