16 research outputs found

    Lane and Road Marking Detection with a High Resolution Automotive Radar for Automated Driving

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    Die Automobilindustrie erlebt gerade einen beispiellosen Wandel, und die Fahrerassistenz und das automatisierte Fahren spielen dabei eine entscheidende Rolle. Automatisiertes Fahren System umfasst haupts\"achlich drei Schritte: Wahrnehmung und Modellierung der Umgebung, Fahrtrichtungsplanung, und Fahrzeugsteuerung. Mit einer guten Wahrnehmung und Modellierung der Umgebung kann ein Fahrzeug Funktionen wie intelligenter Tempomat, Notbremsassistent, Spurwechselassistent, usw. erfolgreich durchf\"uhren. F\"ur Fahrfunktionen, die die Fahrpuren erkennen m\"ussen, werden gegenw\"artig ausnahmslos Kamerasensoren eingesetzt. Bei wechselnden Lichtverh\"altnissen, unzureichender Beleuchtung oder bei Sichtbehinderungen z.B. durch Nebel k\"onnen Videokameras aber empfindlich gest\"ort werden. Um diese Nachteile auszugleichen, wird in dieser Doktorarbeit eine \glqq Radar\textendash taugliche\grqq{} Fahrbahnmakierungerkennung entwickelt, mit der das Fahrzeug die Fahrspuren bei allen Lichtverh\"altnissen erkennen kann. Dazu k\"onnen bereits im Fahrzeug verbaute Radare eingesetzt werden. Die heutigen Fahrbahnmarkierungen k\"onnen mit Kamerasensoren sehr gut erfasst werden. Wegen unzureichender R\"uckstreueigenschaften der existierenden Fahrbahnmarkierungen f\"ur Radarwellen werden diese vom Radar nicht erkannt. Um dies zu bewerkstelligen, werden in dieser Arbeit die R\"uckstreueigenschaften von verschiedenen Reflektortypen, sowohl durch Simulationen als auch mit praktischen Messungen, untersucht und ein Reflektortyp vorgeschlagen, der zur Verarbeitung in heutige Fahrbahnmakierungen oder sogar f\"ur direkten Verbau in der Fahrbahn geeignet ist. Ein weiterer Schwerpunkt dieser Doktorarbeit ist der Einsatz von K\"unstliche Intelligenz (KI), um die Fahrspuren auch mit Radar zu detektieren und zu klassifizieren. Die aufgenommenen Radardaten werden mittels semantischer Segmentierung analysiert und Fahrspurverl\"aufe sowie Freifl\"achenerkennung detektiert. Gleichzeitig wird das Potential von KI\textendash tauglichen Umgebungverstehen mit bildgebenden Radardaten aufgezeigt

    The determination of subtle deformation signals using a permanent CGPS network in the Aegean

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    Geophysical motions can occur over a broad temporal spectrum, from high frequency seismic movements to very long period tectonic deformation. The Aegean region is tectonically one of the most active areas on Earth. There have, over the past 15 years, been a range of campaign style GPS studies which have looked to increase our knowledge of the area and better define the geodynamic processes involved. In 2002 the Center for the Observation and Modelling of Earthquakes and Tectonics (COMET) established a network of continuously operating GPS receivers (CGPS) throughout the region in order to add to the knowledge gained from previous studies. This thesis focuses on which tectonic motions can be observed using the COMET continuous GPS network. Approaches for the precise analytical estimation of subtle tectonic motion are presented. Daily coordinate estimates of COMET sites and a number of ITRF (International Terrestrial Reference Frame) sites around Europe were calculated using a precise point positioning strategy and ambiguity resolution using NASA’s GIPSY – OASIS II processing software and IGS (International GPS Service) precise products. Time series produced showed post fit standard deviations of 2-3 mm in the horizontal and 6-8 mm in the vertical. Significant annual periodic variation is observed in the time series. The coordinate time series studies were further refined using a selection of filters. Firstly, gross and sigma filters were applied to remove outliers, the data then had a range of regional filters applied looking to best define and remove the common mode error in the area. These filters produced mixed results with time series improvement occurring on a site by site basis. In some cases noise was reduced by a factor of 2 whilst in other cases there was little or no improvement. This combined with a lack of knowledge of the individual site movements led to the use of a filtered baseline method, whereby common mode error was removed purely on a site by site basis. This method revealed expansion across the Hellenic arc of the order of a few millimetres per year and sub millimetre north-south compaction behind the arc. It also revealed first evidence of transient motion at a number of sites parallel to the Hellenic arc. The transient signals occurred every 12 months ±1.5 and lasting for 40 – 100 days. These signals were not so much a reversal of tectonic motion akin to the silent earthquakes observed in Cascadia, Japan and Mexico, instead they appeared more as a pause in the otherwise consistent movement of the Aegean microplate overriding the subducting African lithosphere. In addition to the observed tectonic signals, the effects and implications of the two post processing strategies are analysed and discussed. Higher temporal frequency positioning is carried out on seismic events (Mw 6.7 earthquake Kithera, Mw 8.1 and Mw 6.7 earthquakes, Macquarie island) using instantaneous positioning followed by “sidereal filtering” whereby integer-cycle phase ambiguities are resolved using only single epochs of dual frequency phase and pseudorange data. These positions are then siderealy stacked to reduce the effects of geometry related error. The technique reduces geometry related noise by a factor ≈2 using epoch by epoch 30 second data. The feasibility of the technique for observing pre, co and post seismic signals is demonstrated. A visualisation tool was developed to allow the simultaneous observation of the tectonic motion of a CGPS network data over any spatial and temporal regimes

    Quantitative Techniques in Participatory Forest Management

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    Forest management has evolved from a mercantilist view to a multi-functional one that integrates economic, social, and ecological aspects. However, the issue of sustainability is not yet resolved. Quantitative Techniques in Participatory Forest Management brings together global research in three areas of application: inventory of the forest variables that determine the main environmental indices, description and design of new environmental indices, and the application of sustainability indices for regional implementations. All these quantitative techniques create the basis for the development of scientific methodologies of participatory sustainable forest management

    Quantitative Techniques in Participatory Forest Management

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    Forest management has evolved from a mercantilist view to a multi-functional one that integrates economic, social, and ecological aspects. However, the issue of sustainability is not yet resolved. Quantitative Techniques in Participatory Forest Management brings together global research in three areas of application: inventory of the forest variables that determine the main environmental indices, description and design of new environmental indices, and the application of sustainability indices for regional implementations. All these quantitative techniques create the basis for the development of scientific methodologies of participatory sustainable forest management

    Aeolian dune development and evolution on a macro-tidal coast with a complex wind regime, Lincolnshire coast, UK

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    Coastal foredunes are natural aeolian bedforms located landward of the backshore and which interact continuously with the beach. Traditionally, coastal dunes have been associated with onshore winds, however they can be found under more complex wind regimes where offshore winds are common such as the UK East coast, Northern Ireland and New Zealand. This research investigates the ways in which foredune-beach interactions occur under a complex wind regime at a range of overlapping temporal and spatial scales and is innovative in that it explicitly links small-scale processes and morphodynamic behaviour to large scale and long-term dynamics. The study area is the north Lincolnshire coast, East England. Detailed observations of airflow at three locations under varying wind regimes revealed considerable spatial variations in wind velocity and direction, however it was possible to determine a general model of how foredune topography deflected and modified airflow and the resultant geomorphological implications (i.e. erosion and deposition). During direct offshore and onshore winds, airflow remained attached and undeflected; and distinct zones of flow deceleration and acceleration could be identified. During oblique winds airflow was deflected to become more parallel to the dune crest. The field sites used are characterized by a seasonal erosion/accretion cycle and a series of increasingly complex models was developed and tested to determine whether it was possible to predict sand volume changes in the foredune-beach system based on a limited number of variables. The model predictions were tested against detailed digital terrain models at a seasonal timescale. The model prediction that best matched the observed (surveyed) sand volume changes included wind speed, direction, grain size, fetch effect controlled by beach inundation and angle of wind approach was accurate to within ±10% for 18 out of 48 tests at the seasonal scale and 6 out of 12 tests over periods of >5 years. A key variable influencing foredune-beach sand volume is the magnitude and frequency of storm surge events and this was not factored in to the model, but may explain the model-observation mismatch over the medium-term on two occasions. Over the past 120 years historical maps and aerial photographs indicate long-term foredune accretion of approximately 2 m year-1 at the three study sites (1891-2010). At this timescale, rates of coastal foredune accretion reflect the low occurrence of severe storm surges and suggest rapid post-storm recovery. The morphological response of the foredune-beach morphology is considered to be a combination of controlling and forcing factors. Process-responses within the system, associated with nearshore interactions and sediment transfer from the littoral drift, are compiled into a multi-scale morphodynamic model. Important to match appropriate dataset to scale of research question or management plan being explored. In the case of management, long-term records of past activity are necessary to predict the future but also to understand natural responses of system to short-term impact such as storm surge

    Aerial Vehicles

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    This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space

    Simulating academic entrepreneurship and inter-organisational collaboration in university ecosystems, a hybrid system dynamics agent-based simulation

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    Universities are increasingly expected to actively contribute to socio-economic development. Academic entrepreneurship and the evolution of the entrepreneurial university within ecosystems have received increasing attention from both policymakers and academic communities over the last decades. However, most studies on universities' external engagement have focused on individual activities and single universities, hereby neglecting the feedback effects between different activities and how universities are linked through an overlap of their ecosystems. The result is an incomplete understanding of how universities interact with their ecosystem and the resulting inter- and intra-organisational dynamics. This research addresses this issue by developing a hybrid system dynamics agent-based model, which captures feedback structure and the internal decision-making of universities and companies. Both the conceptual and simulation model are based on a triangulation of the literature, interviews with representatives of Scottish universities, and secondary data for Scottish universities and UK businesses. This research makes several theoretical, methodological, and empirical contributions. From a theoretical perspective, it contributes in two distinct ways to the field of entrepreneurship by defining university ecosystems in new way that provides a basis for future research and developing a multi-modal simulation model that can be applied in tested in different contexts. The methodological contributions to the field of modelling and simulation in management science include a modelling process for hybrid simulations, new practices for modelling the size of agent populations through different designs of stocks and flows in the system dynamics module in hybrid simulations, and complex events for recognising emergent behaviour. Lastly, this research makes two empirical contributions to the field of entrepreneurship. This research shines a light on the dynamics of academic entrepreneurship and how universities can partially overcome a low research prestige to increase academic entrepreneurship. Implications for policy and practice are outlined and opportunities for future research conclude this thesis.Universities are increasingly expected to actively contribute to socio-economic development. Academic entrepreneurship and the evolution of the entrepreneurial university within ecosystems have received increasing attention from both policymakers and academic communities over the last decades. However, most studies on universities' external engagement have focused on individual activities and single universities, hereby neglecting the feedback effects between different activities and how universities are linked through an overlap of their ecosystems. The result is an incomplete understanding of how universities interact with their ecosystem and the resulting inter- and intra-organisational dynamics. This research addresses this issue by developing a hybrid system dynamics agent-based model, which captures feedback structure and the internal decision-making of universities and companies. Both the conceptual and simulation model are based on a triangulation of the literature, interviews with representatives of Scottish universities, and secondary data for Scottish universities and UK businesses. This research makes several theoretical, methodological, and empirical contributions. From a theoretical perspective, it contributes in two distinct ways to the field of entrepreneurship by defining university ecosystems in new way that provides a basis for future research and developing a multi-modal simulation model that can be applied in tested in different contexts. The methodological contributions to the field of modelling and simulation in management science include a modelling process for hybrid simulations, new practices for modelling the size of agent populations through different designs of stocks and flows in the system dynamics module in hybrid simulations, and complex events for recognising emergent behaviour. Lastly, this research makes two empirical contributions to the field of entrepreneurship. This research shines a light on the dynamics of academic entrepreneurship and how universities can partially overcome a low research prestige to increase academic entrepreneurship. Implications for policy and practice are outlined and opportunities for future research conclude this thesis
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