79 research outputs found

    PSA based multi objective evolutionary algorithms

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    It has generally been acknowledged that both proximity to the Pareto front and a certain diversity along the front, should be targeted when using evolutionary multiobjective optimization. Recently, a new partitioning mechanism, the Part and Select Algorithm (PSA), has been introduced. It was shown that this partitioning allows for the selection of a well-diversified set out of an arbitrary given set, while maintaining low computational cost. When embedded into an evolutionary search (NSGA-II), the PSA has significantly enhanced the exploitation of diversity. In this paper, the ability of the PSA to enhance evolutionary multiobjective algorithms (EMOAs) is further investigated. Two research directions are explored here. The first one deals with the integration of the PSA within an EMOA with a novel strategy. Contrary to most EMOAs, that give a higher priority to proximity over diversity, this new strategy promotes the balance between the two. The suggested algorithm allows some dominated solutions to survive, if they contribute to diversity. It is shown that such an approach substantially reduces the risk of the algorithm to fail in finding the Pareto front. The second research direction explores the use of the PSA as an archiving selection mechanism, to improve the averaged Hausdorff distance obtained by existing EMOAs. It is shown that the integration of the PSA into NSGA-II-I and Δ p -EMOA as an archiving mechanism leads to algorithms that are superior to base EMOAS on problems with disconnected Pareto fronts. © 2014 Springer International Publishing Switzerland

    Fourth NASA Workshop on Computational Control of Flexible Aerospace Systems, part 1

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    The proceedings of the workshop are presented. Some areas of discussion are as follows: modeling, systems identification, and control of flexible aircraft, spacecraft, and robotic systems

    Mobile Robots

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    The objective of this book is to cover advances of mobile robotics and related technologies applied for multi robot systems' design and development. Design of control system is a complex issue, requiring the application of information technologies to link the robots into a single network. Human robot interface becomes a demanding task, especially when we try to use sophisticated methods for brain signal processing. Generated electrophysiological signals can be used to command different devices, such as cars, wheelchair or even video games. A number of developments in navigation and path planning, including parallel programming, can be observed. Cooperative path planning, formation control of multi robotic agents, communication and distance measurement between agents are shown. Training of the mobile robot operators is very difficult task also because of several factors related to different task execution. The presented improvement is related to environment model generation based on autonomous mobile robot observations

    Innovation, Research and Development and Capital Evaluation

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    The role of innovation is becoming increasingly crucial in modern societies. In particular, investments in Research and Development represent an important tool for promoting innovation and for enhancing the capital invested in the market. By now, innovation is linked with different concepts, from entrepreneurship to sustainability, from economics to management. The analysis of the innovation process involves different skills to overcome the high degree of competitiveness and allow higher levels of profits. In the text, the interactions among innovation, entrepreneurship, and ecosystems are investigated. It is an attempt to prepare the theoretical bases to face in an appropriate way the transformations of modern economic and organizational systems and to suggest adequate support policies

    The application of systematic conservation planning in the succulent Karoo biome of South Africa

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    Systematic conservation planning is about making spatially explicit decisions regarding the use of land, based on the observed or expected biodiversity present at a site and the potential for that same site to support alternative /and-uses that are not compatible with the persistence of biodiversity. This thesis examines three questions relating to the application of systematic conservation planning: Which biodiversity surrogates should be used in Namaqualand to do systematic conservation plans? How should targets be set for these surrogates? How can this information be integrated and used within a systematic conservation planning framework? Comparing how well different biodiversity surrogates achieved a set of targets illustrated that continuous biodiversity data (i.e. vegetation types and land-classes) perform better as surrogates than point-based species distribution data. Quarter degree square-based species distribution data cannot be used for on-the-ground conservation planning. It was demonstrated that it is possible to set biologically meaningful conservation targets to represent biodiversity pattern in land classes by applying the Species Area Relationship and using plot-based survey data. The method developed here has the potential to revolutionise conservation planning as it provides for the first time a defensible means for setting representation targets for land classes that are grounded on ecological theory and that use real data. The thesis also explores the potential for metapopulation and fragmentation studies to provide useful insights into developing targets for ecological processes by relating the amount of remaining habitat to key thresholds in probability of population persistence. Two examples, at different spatial scales (1:10 000 and 1:100 000), are used to illustrate how different biodiversity information can be integrated and used within a systematic conservation planning framework. At the finer scale biodiversity and land-use data are 3 used to set priorities for the development of a statutory reserve in the Knersvlakte region of the Succulent Karoo using cadastres as planning units. At the larger scale the data are used in the same region to design a biosphere reserve that promotes the persistence of ecological processes in the landscape using gridded planning units. Both studies use the C-Plan software to assist in the planning and design process. A lesson from both these studies is that there needs to be a paradigm shift in conservation from an on/off reserve mindset to a more integrative whole landscape mindset

    Space station systems: A bibliography with indexes (supplement 2)

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    This bibliography lists 904 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1, 1985 and December 31, 1985. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems. The coverage includes documents that define major systems and subsystems, servicing and support requirements, procedures and operations, and missions for the current and future space station
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