623 research outputs found

    Weak heaps and friends:recent developments

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    Retrieval and Annotation of Music Using Latent Semantic Models

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    PhDThis thesis investigates the use of latent semantic models for annotation and retrieval from collections of musical audio tracks. In particular latent semantic analysis (LSA) and aspect models (or probabilistic latent semantic analysis, pLSA) are used to index words in descriptions of music drawn from hundreds of thousands of social tags. A new discrete audio feature representation is introduced to encode musical characteristics of automatically-identified regions of interest within each track, using a vocabulary of audio muswords. Finally a joint aspect model is developed that can learn from both tagged and untagged tracks by indexing both conventional words and muswords. This model is used as the basis of a music search system that supports query by example and by keyword, and of a simple probabilistic machine annotation system. The models are evaluated by their performance in a variety of realistic retrieval and annotation tasks, motivated by applications including playlist generation, internet radio streaming, music recommendation and catalogue searchEngineering and Physical Sciences Research Counci

    Safety Aware Vehicle Routing Algorithm, A Weighted Sum Approach

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    Driving is an essential part of work life for many people. Although driving can be enjoyable and pleasant, it can also be stressful and dangerous. Many people around the world are killed or seriously injured while driving. According to the World Health Organization (WHO), about 1.25 million people die each year as a result of road traffic crashes. Road traffic injuries are also the leading cause of death among young people. To prevent traffic injuries, governments must address road safety issues, an endeavor that requires involvement from multiple sectors (transport, police, health, education). Effective intervention should include designing safer infrastructure and incorporating road safety features into land-use and transport planning. The aim of this research is to design an algorithm to help drivers find the safest path between two locations. Such an algorithm can be used to find the safest path for a school bus travelling between bus stops, a heavy truck carrying inflammable materials, poison gas, or explosive cargo, or any driver who wants to avoid roads with higher numbers of accidents. In these applications, a path is safe if the danger factor on either side of the path is no more than a given upper bound. Since travel time is another important consideration for all drivers, the suggested algorithm utilizes traffic data to consider travel time when searching for the safest route. The key achievements of the work presented in this thesis are summarized as follows. Defining the Safest and Quickest Path Problem (SQPP), in which the goal is to find a short and low-risk path between two locations in a road network at a given point of time. Current methods for representing road networks, travel times and safety level were investigated. Two approaches to defining road safety level were identified, and some methods in each approach were presented. An intensive review of traffic routing algorithms was conducted to identify the most well-known algorithms. An empirical study was also conducted to evaluate the performance of some routing algorithms, using metrics such as scalability and computation time. This research approaches the SQPP problem as a bi-objective Shortest Path Problem (SPP), for which the proposed Safety Aware Algorithm (SAA) aims to output one quickest and safest route. The experiments using this algorithm demonstrate its efficacy and practical applicability

    Satellite based synthetic aperture radar and optical spatial-temporal information as aid for operational and environmental mine monitoring

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    A sustainable society is a society that satisfies its resource requirements without endangering the sustainability of these resources. The mineral endowment on the African continent is estimated to be the first or second largest of world reserves. Therefore, it is recognised that the African continent still heavily depends on mineral exports as a key contributor to the gross domestic product (GDP) of various countries. These mining activities, however, do introduce primary and secondary environmental degradation factors. They attract communities to these mining areas, light and heavy industrial establishments occur, giving rise to artisanal activities. This study focussed on satellite RS products as an aid to a mine’s operations and the monitoring of its environment. Effective operational mine management and control ensures a more sustainable and profitable lifecycle for mines. Satellite based RS holds the potential to observe the mine and its surrounding areas at high temporal intervals, different spectral wavelengths and spatial resolutions. The combination of SAR and optical information creates a spatial platform to observe and measure the mine’s operations and the behaviour of specific land cover and land use classes over time and contributes to a better understanding of the mining activities and their influence on the environment within a specific geographical area. This study will introduce an integrated methodology to collect, process and analyse spatial information over a specific targeted mine. This methodology utilises a medium resolution land cover base map, derived from Landsat 8, to understand the predominant land cover types of the surrounding area. Using very high resolution mono- and stereoscopic satellite imagery provides a finer scale analysis and identifies changes in features at a smaller scale. Combining these technologies with the synthetic aperture radar (SAR) applications for precise measurement of surface subsidence or upliftment becomes a spatial toolbox for mine management. This study examines a combination of satellite remote sensing products guided by a systematic workflow methodology to integrate spatial results as an aid for mining operations and environmental monitoring. Some of the results that can be highlighted is the successful land cover classification using the Landsat 8 satellite. The land cover that dominated the Kolomela mine area was the “SHRUBLAND/GRASS” class with a 94% coverage and “MINE” class of 2.6%. Sishen mine had a similar dominated land cover characteristic with a “SHRUBLAND/GRASS” class of 90% and “MINE” class of 4.8%. The Pléiades time-series classification analysis was done using three scenes each acquired at a different time interval. The Sishen and Kolomela mine showed especially changes from the bare soil class to the asphalt or mine class. The Pléiades stereoscopic analysis provided volumetric change detection over small, medium, large and recessed areas. Both the Sishen and Kolomela mines demonstrated height profile changes in each selected category. The last category of results focused on the SAR technology to measure within millimetre accuracy the subsidence and upliftment behaviour of surface areas over time. The Royal Bafokeng Platinum tailings pond area was measured using 74 TerraSAR-X scenes. The tailings wall area was confirmed as stable with natural subsidence that occurred in its surrounding area due to seasonal changes of the soil during rainy and dry periods. The Chuquicamata mine as a large open pit copper mine area was analysed using 52 TerraSAR-X scenes. The analysis demonstrated significant vertical surface movement over some of the dumping sites. It is the wish of the researcher that this dissertation and future research scholars will continue to contribute in this scientific field. These contributions can only assist the mining sector to continuously improve its mining operations as well as its monitoring of the primary as well as the secondary environmental impacts to ensure improved sustainability for the next generation.Environmental SciencesM. Sc. (Environmental Science

    Algorithms for Triangles, Cones & Peaks

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    Three different geometric objects are at the center of this dissertation: triangles, cones and peaks. In computational geometry, triangles are the most basic shape for planar subdivisions. Particularly, Delaunay triangulations are a widely used for manifold applications in engineering, geographic information systems, telecommunication networks, etc. We present two novel parallel algorithms to construct the Delaunay triangulation of a given point set. Yao graphs are geometric spanners that connect each point of a given set to its nearest neighbor in each of kk cones drawn around it. They are used to aid the construction of Euclidean minimum spanning trees or in wireless networks for topology control and routing. We present the first implementation of an optimal O(nlogn)\mathcal{O}(n \log n)-time sweepline algorithm to construct Yao graphs. One metric to quantify the importance of a mountain peak is its isolation. Isolation measures the distance between a peak and the closest point of higher elevation. Computing this metric from high-resolution digital elevation models (DEMs) requires efficient algorithms. We present a novel sweep-plane algorithm that can calculate the isolation of all peaks on Earth in mere minutes

    Forgotten as data – remembered through information. Social memory institutions in the digital age: the case of the Europeana Initiative

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    The study of social memory has emerged as a rich field of research closely linked to cultural artefacts, communication media and institutions as carriers of a past that transcends the horizon of the individual’s lifetime. Within this domain of research, the dissertation focuses on memory institutions (libraries, archives, museums) and the shifts they are undergoing as the outcome of digitization and the diffusion of online media. Very little is currently known about the impact that digitality and computation may have on social memory institutions, specifically, and social memory, more generally – an area of study that would benefit from but, so far, has been mostly overlooked by information systems research. The dissertation finds its point of departure in the conceptualization of information as an event that occurs through the interaction between an observer and the observed – an event that cannot be stored as information but merely as data. In this context, memory is conceived as an operation that filters, thus forgets, the singular details of an information event by making it comparable to other events according to abstract classification criteria. Against this backdrop, memory institutions are institutions of forgetting as they select, order and preserve a canon of cultural heritage artefacts. Supported by evidence from a case study on the Europeana initiative (a digitization project of European libraries, archives and museums), the dissertation reveals a fundamental shift in the field of memory institutions. The case study demonstrates the disintegration of 1) the cultural heritage artefact, 2) its standard modes of description and 3) the catalogue as such into a steadily accruing assemblage of data and metadata. Dismembered into bits and bytes, cultural heritage needs to be re-membered through the emulation of recognizable cultural heritage artefacts and momentary renditions of order. In other words, memory institutions forget as binary-based data and remember through computational information

    Tsunami Hazard in Eastern Indonesia: Source Identification and Reconstruction for Historical Case Studies

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    The archipelagic country of Indonesia is vulnerable to tsunami hazard due to its tectonic setting. An updated tsunami catalogue numbers at least 133 tsunamis documented from 1608 to 2018. Approximately 80% of tsunamis in Indonesia were generated by earthquakes. Eastern Indonesia experienced almost double the number of tsunamis than western of Indonesia, as separated by the Wallace Line. It is almost certain that the Sunda subduction zone and Krakatau (including Anak Krakatau) generated all tsunamis in the western part of Indonesia. However, it is more difficult to determine the primary source of tsunamis in the eastern region. Observations of these tsunamis are documented in several tsunami catalogues. Most of the events begin with a description of ground motion felt by local people at various locations, which as then followed by a tsunami. For several major events, there was detailed information on the physical tsunami behaviour observed at several places. For events in eastern Indonesia, there is no detailed information on the primary source of the ground motion and the tsunami. The aims of this study are 1) to develop techniques to optimise information from sparse and incomplete historical accounts using three case studies from eastern Indonesia: a) the Ambon Island 1674, b) the Banda Sea 1852, and c) the Flores Island 1992 tsunamis, and 2) to identify and reconstruct the primary source of the ground motion and tsunami for each event. The Ambon Island 1674 earthquake and tsunami has the oldest detailed historical account in Indonesia. It was also the largest tsunami run-up height ever documented in Indonesia, reaching about 100 m only on the northern shore of Ambon, whereas minor tsunamis were observed at other locations. The accounts gave detailed information on the earthquake intensities and tsunami observations from Ambon and its surrounding islands. Through a process of eliminating the well-known faults around the island and tsunami modelling, the most credible source to explain the tsunami observation was determined to be a landslide from the northern shore of Ambon. The earthquake source is still unclear. However, the ground motions were caused by a local and shallow depth earthquake. This study found that the Banda Sea 1852 earthquake and tsunami was the first event known in which a major tsunami was generated by a very low-angle normal fault, in this case known as the Banda Detachment. This conclusion is reached by combining a tsunami inverse travel time simulation, an earthquake intensity inversion, and tsunami modelling. An earthquake from the Banda Detachment can generate high intensity ground motion on the Banda Islands that gradually decreases towards Ternate in the north. Moreover, a landslide triggered by the Banda Detachment explains why people at Banda Neira and Ambon observed a tsunami that arrived with a positive phase polarity, unlike previous studies hypothesizing a source on the Tanimbar Trough. The source of the Flores Island 1992 earthquake and tsunami is constrained using a finite-fault source inversion technique. In this study, multiple data types are utilised together to provide an alternative solution to the rupture area, which has never been done in previous studies of this event. Through this technique and careful analysis of the fault plane model, the strike of the earthquake is confirmed to be 70deg. This fault geometry raises new questions about segmentation on the Flores back-arc thrust. Lastly, this study recommends a major modification for tsunami and earthquake hazard in eastern Indonesia. Firstly, all of events studied potentially involved landslides, so that landslides have to be considered in any tsunami hazard assessment. Secondly, the Banda Detachment is a major tsunami and earthquake source in the Banda Sea region. Lastly, the Flores back-arc thrust is a segmented zone. These factors will dramatically change the potential seismic and tsunami hazard distribution in this region

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    Challenges in Cybersecurity and Privacy - the European Research Landscape

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    Cybersecurity and Privacy issues are becoming an important barrier for a trusted and dependable global digital society development. Cyber-criminals are continuously shifting their cyber-attacks specially against cyber-physical systems and IoT, since they present additional vulnerabilities due to their constrained capabilities, their unattended nature and the usage of potential untrustworthiness components. Likewise, identity-theft, fraud, personal data leakages, and other related cyber-crimes are continuously evolving, causing important damages and privacy problems for European citizens in both virtual and physical scenarios. In this context, new holistic approaches, methodologies, techniques and tools are needed to cope with those issues, and mitigate cyberattacks, by employing novel cyber-situational awareness frameworks, risk analysis and modeling, threat intelligent systems, cyber-threat information sharing methods, advanced big-data analysis techniques as well as exploiting the benefits from latest technologies such as SDN/NFV and Cloud systems. In addition, novel privacy-preserving techniques, and crypto-privacy mechanisms, identity and eID management systems, trust services, and recommendations are needed to protect citizens’ privacy while keeping usability levels. The European Commission is addressing the challenge through different means, including the Horizon 2020 Research and Innovation program, thereby financing innovative projects that can cope with the increasing cyberthreat landscape. This book introduces several cybersecurity and privacy research challenges and how they are being addressed in the scope of 15 European research projects. Each chapter is dedicated to a different funded European Research project, which aims to cope with digital security and privacy aspects, risks, threats and cybersecurity issues from a different perspective. Each chapter includes the project’s overviews and objectives, the particular challenges they are covering, research achievements on security and privacy, as well as the techniques, outcomes, and evaluations accomplished in the scope of the EU project. The book is the result of a collaborative effort among relative ongoing European Research projects in the field of privacy and security as well as related cybersecurity fields, and it is intended to explain how these projects meet the main cybersecurity and privacy challenges faced in Europe. Namely, the EU projects analyzed in the book are: ANASTACIA, SAINT, YAKSHA, FORTIKA, CYBECO, SISSDEN, CIPSEC, CS-AWARE. RED-Alert, Truessec.eu. ARIES, LIGHTest, CREDENTIAL, FutureTrust, LEPS. Challenges in Cybersecurity and Privacy - the European Research Landscape is ideal for personnel in computer/communication industries as well as academic staff and master/research students in computer science and communications networks interested in learning about cyber-security and privacy aspects
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