239,786 research outputs found

    Adaptive Learning Terrain Estimation for Unmanned Aerial Vehicle Applications

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    For the past decade, terrain mapping research has focused on ground robots using occupancy grids and tree-like data structures, like Octomap and Quadtrees. Since flight vehicles have different constraints, ground-based terrain mapping research may not be directly applicable to the aerospace industry. To address this issue, Adaptive Learning Terrain Estimation algorithms have been developed with an aim towards aerospace applications. This thesis develops and tests Adaptive Learning Terrain Estimation algorithms using a custom test benchmark on representative aerospace cases: autonomous UAV landing and UAV flight through 3D urban environments. The fundamental objective of this thesis is to investigate the use of Adaptive Learning Terrain Estimation algorithms for aerospace applications and compare their performance to commonly used mapping techniques such as Quadtree and Octomap. To test the algorithms, point clouds were collected and registered in simulation and real environments. Then, the Adaptive Learning, Quadtree, and Octomap algorithms were applied to the data sets, both in real-time and offline. Finally, metrics of map size, accuracy, and running time were developed and implemented to quantify and compare the performance of the algorithms. The results show that Quadtree yields the computationally lightest maps, but it is not suitable for real-time implementation due to its lack of recursiveness. Adaptive Learning maps are computationally efficient due to the use of multiresolution grids. Octomap yields the most detailed maps, but it produces a high computational load. The results of the research show that Adaptive Learning algorithms have significant potential for real-time implementation in aerospace applications. Their low memory load and variable-sized grids make them viable candidates for future research and development

    Social-ecological innovation : adaptive responses to urban environmental conditions

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    Novel approaches to natural resource management, particularly those which promote stakeholder participation, have been put forward as fundamental ingredients for establishing resilient, polycentric forms of environmental governance. This is nowhere more pertinent than in the case of the complex adaptive systems associated with urban areas. Decentralisation of urban green space management has been posited as an element thereof which, according to resilience thinking, should contribute to the adaptive capacity of cities and the ecosystem services upon which they rely. Implicit in this move towards increased adaptive capacity is the ability to manage through innovation. Although the importance of innovation towards system adaptability has been acknowledged, little work has thus far been carried out which demonstrates that innovative use of urban green space represents a form of adaptive response to environmental conditions. The current paper reports on research which maps examples of organised social-ecological innovation (OSEI) in an urban study area and evaluates them as adaptive responses to local environmental conditions which may contribute to system resilience. The results present OSEI as a coherent body of responses to local social and environmental deprivation, exhibiting diversity and adaptability according to individual contexts. The study therefore provides evidence for the importance of local stakeholder-led innovation as in the building of adaptive capacity in urban social-ecological systems

    Generative Design in Minecraft (GDMC), Settlement Generation Competition

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    This paper introduces the settlement generation competition for Minecraft, the first part of the Generative Design in Minecraft challenge. The settlement generation competition is about creating Artificial Intelligence (AI) agents that can produce functional, aesthetically appealing and believable settlements adapted to a given Minecraft map - ideally at a level that can compete with human created designs. The aim of the competition is to advance procedural content generation for games, especially in overcoming the challenges of adaptive and holistic PCG. The paper introduces the technical details of the challenge, but mostly focuses on what challenges this competition provides and why they are scientifically relevant.Comment: 10 pages, 5 figures, Part of the Foundations of Digital Games 2018 proceedings, as part of the workshop on Procedural Content Generatio

    A spatially explicit and quantitative vulnerability assessment of ecosystem service change in Europe

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    Environmental change alters ecosystem functioning and may put the provision of services to human at risk. This paper presents a spatially explicit and quantitative assessment of the corresponding vulnerability for Europe, using a new framework designed to answer multidisciplinary policy relevant questions about the vulnerability of the human-environment system to global change. Scenarios were constructed for a range of possible changes in socio-economic trends, land uses and climate. These scenarios were used as inputs in a range of ecosystem models in order to assess the response of ecosystem function as well as the changes in the services they provide. The framework was used to relate the impacts of changing ecosystem service provision for four sectors in relation to each other, and to combine them with a simple, but generic index for societal adaptive capacity. By allowing analysis of different sectors, regions and development pathways, the vulnerability assessment provides a basis for discussion between stakeholders and policymakers about sustainable management of Europe¿s natural resource

    Continuous use of authoring for adaptive educational hypermedia : a long-term case study

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    Adaptive educational hypermedia allows lessons to be personalized according to the needs of the learner. However, to achieve this, content must be split into stand-alone fragments that can be processed by a course personalization engine. Authoring content for this process is still a difficult activity, and it is essential for the popularization of adaptive educational hypermedia that authoring is simplified, so that the various stakeholders in the educational process, students, teachers, administrators, etc. can easily work with such systems. Thus, real-world testing with these stakeholders is essential. In this paper we describe recent extensions and improvements we have implemented in the My Online Teacher MOT3.0 adaptation authoring tool set, based on an initial set of short-term evaluations, and then focus on describing a long-term usage and assessment of the system

    Towards High Performance Video Object Detection

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    There has been significant progresses for image object detection in recent years. Nevertheless, video object detection has received little attention, although it is more challenging and more important in practical scenarios. Built upon the recent works, this work proposes a unified approach based on the principle of multi-frame end-to-end learning of features and cross-frame motion. Our approach extends prior works with three new techniques and steadily pushes forward the performance envelope (speed-accuracy tradeoff), towards high performance video object detection

    The Next Generation Virgo Cluster Survey. VIII. The Spatial Distribution of Globular Clusters in the Virgo Cluster

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    We report on a large-scale study of the distribution of globular clusters (GCs) throughout the Virgo cluster, based on photometry from the Next Generation Virgo Cluster Survey, a large imaging survey covering Virgo's primary subclusters to their virial radii. Using the g', (g'-i') color-magnitude diagram of unresolved and marginally-resolved sources, we constructed 2-D maps of the GC distribution. We present the clearest evidence to date showing the difference in concentration between red and blue GCs over the extent of the cluster, where the red (metal-rich) GCs are largely located around the massive early-type galaxies, whilst the blue (metal-poor) GCs have a more extended spatial distribution, with significant populations present beyond 83' (215 kpc) along the major axes of M49 and M87. The GC distribution around M87 and M49 shows remarkable agreement with the shape, ellipticity and boxiness of the diffuse light surrounding both galaxies. We find evidence for spatial enhancements of GCs surrounding M87 that may be indicative of recent interactions or an ongoing merger history. We compare the GC map to the locations of Virgo galaxies and the intracluster X-ray gas, and find good agreement between these baryonic structures. The Virgo cluster contains a total population of 67300±\pm14400 GCs, of which 35% are located in M87 and M49 alone. We compute a cluster-wide specific frequency S_N,CL=2.8±0.72.8\pm0.7, including Virgo's diffuse light. The GC-to-baryonic mass fraction is e_b=5.7±1.1×10−45.7\pm1.1\times10^{-4} and the GC-to-total cluster mass formation efficiency is e_t=2.9±0.5×10−52.9\pm0.5\times10^{-5}, values slightly lower than, but consistent with, those derived for individual galactic halos. Our results show that the production of the complex structures in the unrelaxed Virgo cluster core (including the diffuse intracluster light) is an ongoing process.(abridged)Comment: 23 pages, 17 figures. Accepted for publication in the Astrophysical Journal. Figure 1 has reduced resolution. Revised version with updated references, corrected typos -- no changes to result
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