1,720,965 research outputs found
Safety Risk Assessment in Aircraft Fuel Planning and Management
No full textIn this report we demonstrate the outcomes of the research performed in the Air Transport Safety Institute of the Royal Netherlands Aerospace Centre (NLR). This research project constitutes the MSc Thesis of the writer, towards the graduation of the MSc Aerospace Engineering at Delft University of Technology (Air Transport & Operations). The subject of this project lies in the area of aviation safety and quantitative risk assessment. In specific, the study deals with the safety issue of fuel planning and fuel management in airlines’ operations (Commercial Air Transport). As the air traffic growths rapidly, it is a challenge to keep the current safety levels and further improve them, achieving the EU’s vision safety target, which is less than one accident per ten million flights by 2050. Amongst the various accidents and incidents categories, this project researches the accidents and incidents related to fuel. In specific, we investigate two fuel-related events; the probability that a flight lands with less than the minimum regulated fuel amount (called FRF - Final Reserve Fuel) and the probability of fuel exhaustion. So as to analyse and assess the safety risks, we followed the steps of the TOPAZ methodology. Based on previous research on the subject, an extensive hazards list was created, as well as an agent-based risk model was developed and implemented as a Stochastic Dynamically Coloured Petri Nets (SDCPN) model. The risk model was algorithmically implemented in JAVA programming language, in the direction of conducting Monte Carlo simulations. The first event's (FRF) probabilities were estimated through regular (straightforward) Monte Carlo simulation, whilst for the second (fuel exhaustion) regular Monte Carlo proved to be insufficient. Indeed, fuel exhaustion is a rare event and, consequently, an acceleration method was needed to be implemented. The acceleration method chosen is the Interacting Particle System (IPS). Finally, through the simulations, we estimate the probabilities of these rare events for several operational scenarios. The fuel-related risks were assessed for their acceptability, eventually proving that for all scenarios the risks are either tolerable or acceptable, while also the most prominent safety bottlenecks are identified and analysed.Aerospace Engineerin
Agent-based modelling and simulation for quantification of resilience in air transport: The effects of a sudden and unexpected bad weather disturbance on conventional approach operations
No full textSocio-technical systems consist of deeply interconnected and interdependent social entities and technical systems that collaborate to achieve a global goal. The individual characteristics and behaviours of each involved actor and their interactions define the resulting overall emergent system behaviour. Due to increased complexities in socio-technical systems traditional safety risk assessment strategies are found to become less suitable to predict, to reveal and to understand emergent system behaviour. In recent years there has therefore been a shift in the way how safety in complex socio-technical systems is perceived. The relatively new safety management paradigm called resilience engineering focusses on the ability of socio-technical systems to cope with varying conditions by applying everyday performance. Recent studies related to resilience engineering insist on the need for more structured modelling approaches for analysis and quantification of resilience in socio-technical systems. This study contributes to this need by presenting a quantitative agent-based modelling and simulation approach. The suitability of such approach for more profound analysis and quantification of resilience in socio-technical systems has been studied in the context of conventional approach operations during a sudden and unexpected bad weather disturbance. The formal agent-based model that has been developed for this resilience study especially emphasized the role of executive controllers in achieving and maintaining resilience. The adaptive strategies that are considered for this purpose are multiple vectoring strategies, the initiation of holding operations and go-arounds. The resilient capacities of conventional approach operations have been quantified using the emergent outcomes of these adaptive strategies. Considering the obtained simulation results and gained insight there can be concluded that quantitative agent-based modelling and simulation is a suitable, structured and powerful approach for more profound analysis and quantification of resilience in socio-technical systems.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
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
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