1,723,556 research outputs found
Haptic gas pedal feedback for active car-following support
No full textThe research presented in this dissertation focuses on supporting drivers in the longitudinal control of their vehicle during car-following. The goal of the research is the human-centred development of a haptic gas pedal interface that comfortably supports drivers in maintaining a safe separation with a leading vehicle during car-following. Two different approaches were found to be suitable for implementation as haptic information providers through the gas pedal. The first approach was to add a force to the gas pedal dynamics which would have to be related to the safe-field-of-travel ahead of the own vehicle and changes therein. The gas pedal dynamics, that is, the force/pedal-position relationship is not changed by this approach. The second approach was to change the stiffness of the gas pedal by adding a virtual stiffness to the inherent stiffness of the gas pedal. By doing so, the dynamics of the gas pedal are changed depending on the changes detected in the safe-field-of-travel. In both approaches, an electrical actuator provides the additional force or stiffness. The main hypothesis of this dissertation is the assumption that with the appropriate haptic feedback of longitudinal traffic information drivers will adopt a force-task in controlling the haptic gas pedal. Experimental verification leads to the conclusion that the stiffness feedback design with time-to-contact information scaled by time headway performs best in this respect.Aerospace Engineerin
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
Airborne Conflict Resolution in Three Dimensions
No full textThe advent of automation in the cockpit has greatly affected the nature of the tasks on the flight deck, as well as requirements on the flight crew. Although the introduction of automation in aircraft undeniably improved performance and safety, it also increased complexity in the cockpit. In addition to knowledge of basic flight information, pilots are nowadays also required to keep track of how their automated systems work. This requires a coordination of tasks between automation and human actors, and a transparency of automation that can currently not always be guaranteed. The focus of this thesis is on the concept of airborne separation, which is proposed as part of both European and American plans for the future air-traffic management system. Such a system of airborne separation implies either partial or full delegation of separation responsibility from the controller to the aircrew. This should reduce workload for the controller on the ground, and consequently increase airspace capacity, but will also lead to a profound change on the flight deck. These plans will, in order to be realized, have substantial consequences for the degree of automation, both on the ground and in the cockpit. In this thesis it is argued that capturing the inherent work domain information in a functional representation should be the basis for automating the task of airborne separation. To accomplish this, a constraint-based approach, inspired by Ecological Interface Design (EID), was employed, to provide the basis for a transparent interface to automation. This method aims to make the structure of the work domain salient, and in addition to providing a basis for automation design, should yield an interface that facilitates transparency of automation, and should support operators in constructing situation awareness. Results from experiments presented in this thesis show that, regardless of the limited level of training that the participants received, they are able to use the interface concepts to find efficient resolutions. Because these kinds of displays make several complex relationships directly perceivable, they relieve pilots from cognitive work. This transforms what would otherwise be a task that requires knowledge-based problem solving, into a simple task of perception and observation, where pilots can apply basic skills and predefined rules to safely and efficiently resolve a conflict. This allows pilots to perform well, even with a limited amount of training.Control and SimulationAerospace Engineerin
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
Objective Evaluation of Flight Simulator Motion Cueing Fidelity Through a Cybernetic Approach
No full textCompared to aircraft, flight simulators are severely limited in their motion envelopes. Presenting the true aircraft motion one-to-one on flight simulators is generally impossible and it is therefore common practice that these motion stimuli are only presented in reduced and attenuated form. Because of a limited understanding of human motion perception processes and how these affect the perceived realism of the multimodal stimuli pilots are subjected to during aircraft control (most notably, visual and physical motion stimuli), the definition of requirements for flight simulator motion cueing fidelity is a problem that researchers and legislators have struggled with for years. This thesis therefore describes and evaluates an objective method for the assessment of simulator cueing motion fidelity. The proposed method is centered around an analysis of the control dynamics adopted by pilots during manual control tasks, and how they use visual and motion stimuli in their selected control strategy, using multimodal pilot models. This approach thereby allows for the objective and quantitative evaluation of flight simulator motion fidelity, by explicitly considering how degraded motion cueing fidelity affects a simulator's ability to induce real-flight manual control behavior. This thesis describes a number of experiments in which pilot manual control behavior was measured using this approach in the Cessna Citation II laboratory aircraft and the SIMONA Research Simulator at Delft University of Technology. A comparison of the collected measurements clearly shows that variations in simulator motion cueing fidelity result in changes in pilot manual control behavior. With increased motion cueing fidelity, pilots are seen to rely significantly more on the presented motion stimuli, a control strategy that also typically results in increased manual control performance. Furthermore, these experiments also show that important behavioral parameters that characterize the weighing of visual and motion information by pilots also correspond best with those measured for in-flight pilot behavior when simulator motion cues are close to those of real flight.Control & SimulationAerospace Engineerin
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