1,720,956 research outputs found
Development of a decision support framework for systems architecting in aerospace applications
No full textThe exploration of the architectural solution space tends to be iterative, where multiple system architectures are explored over several cycles before a final solution is selected. However the time and cost required to conduct this activity can be significant in the presence of multiple system architectures. This thesis presents a decision support framework that assists the system architect in generating, analysing, and identifying optimal system architectures. The framework achieves this by using a formal modelling approach that represents the architectural decision-making process as a Constraint Optimisation Problem (COP), resulting in a graph representation of interconnected architectural decision variables. The graph-based approach provides computational tools that enables the system architect to automatically synthesise viable architectures based on the constraints defined, and calculate high-impact decision variables within the network. This capability is enabled by synthesising concepts from decision theory, multi-objective optimisation, and centrality measures from network analysis to provide a visual representation of high-impact decision variables. In applying this framework to the design of a low-cost Unmanned Aircraft System (UAS), we identify the choice of design alternatives relating to the implementation of the payload sensor system to have a high-impact on system properties and network connectivity. Suggesting that the exploration of the solution space should be focused towards payload implementation
Development of a decision support framework for systems architecting in aerospace applications
No full textThis paper describes the development of a new decision support framework that assists system designers in identifying optimal architectural concepts, and a more focused design exploration strategy with the aim of improving system utility, and reducing life-cycle cost(LCC). The framework developed has been applied to the design of a low-cost Unmanned Aerial Vehicle (UAV) for use in coastal monitoring and search and rescue operations. The case study was used to demonstrate the applicability of the framework in allowing system designers to generate and trade between different architectural concepts, and also numerically capture the rationale behind the decision-making process. This is achieved by using a formal modelling approach that defines the architectural decision-making process as a network, whereby the nodes of the network represent system functions and the connecting edges represent the physical/preferential constraints declared by the decision maker on the architectural solution space. In addition, the framework makes use of multi-objective optimization methodologies, in combination with centrality measures from graph theory and a modified version of the main effects analysis from the Design of Experiments (DoE) literature, to identify Pareto optimal solutions and a focused architectural exploration strategy with the aim of improving upon the solutions within the Pareto set
Better design decisions through operational modeling during the early design phases
No full textThis work presents an operational simulation based on a unique mission ontology that enables recreating any aviation scenario using a small set of parameters. The tool is designed to suit the early design phases where time pressures, uncertainties and knowledge gaps peak. It is embedded in a stack of software allowing early design phase optimization based on operational constraints. This stack was used to design and build several Unmanned Aerial Vehicles. Two case studies demonstrate how the tool can act as a decision support or optimization tool, leading to improved designs and better operations. It is found that early design decisions can be based on a more rigorous analysis and that it is possible to optimize both the design and the operational environment by employing an operational simulation
The challenges of using value-driven design for practical design of UAVs
No full textThe Decision Environment for Complex Designs (DECODE) project at the University of Southampton aims to provide a multidisciplinary environment to support and improve design decisions in order to maximize long term product value. This approach involves the analysis of the overall product life-cycle, from conceptual design to the end of its service life. This paper discusses the issues faced and the limitations of the DECODE framework in the design, search and optimisation of multiple UAV configurations. The fundamental issue lies in the calculation of value metric, which indicates the ‘goodness’ of the system. The value metric used is based on Net-Present-Value (NPV) where a monetary value is assigned to mission success. In the case of search and rescue operations it is the value of saving a human life. This paper also explores the possible solutions to increase the flexibility of the DECODE design tool. Central to the DECODE design process is the concept design tool which was developed from basic principles and augmented with empirical data coming from previous UAVs designs. This however, limits the assessment of various UAV configurations as the runtime for each configuration is significant which makes the evaluation of multiple UAV systems infeasible. A more rapid assessment methodology is proposed: this involves a Knowledge-based Framework (KBF) that allows the user to explore various UAV configurations and down select from them using requirements. This framework is based on an aircraft domain ontology and logic inference, which utilizes semantic-web-tools and an organized flow of information that ensures clarity in the decisions made
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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