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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Identification of Fundamental Driving Scenarios Using Unsupervised Machine Learning / Identifiering av grundläggande körscenarier med icke-guidad maskininlärning

Anantha Padmanaban, Deepika January 2020 (has links)
A challenge to release autonomous vehicles to public roads is safety verification of the developed features. Safety test driving of vehicles is not practically feasible as the acceptance criterion is driving at least 2.1 billion kilometers [1]. An alternative to this distance-based testing is the scenario-based approach, where the intelligent vehicles are exposed to known scenarios. Identification of such scenarios from the driving data is crucial for this validation. The aim of this thesis is to investigate the possibility of unsupervised identification of driving scenarios from the driving data. The task is performed in two major parts. The first is the segmentation of the time series driving data by detecting changepoints, followed by the clustering of the previously obtained segments. Time-series segmentation is approached using a Deep Learning method, while the second task is performed using time series clustering. The work also includes a visual approach for validating the time-series segmentation, followed by a quantitative measure of the performance. The approach is also qualitatively compared against a Bayesian Nonparametric approach to identify the usefulness of the proposed method. Based on the analysis of results, there is a discussion about the usefulness and drawbacks of the method, followed by the scope for future research. / En utmaning att släppa autonoma fordon på allmänna vägar är säkerhetsverifiering av de utvecklade funktionerna. Säkerhetstestning av fordon är inte praktiskt genomförbart eftersom acceptanskriteriet kör minst 2,1 miljarder kilometer [1]. Ett alternativ till denna distansbaserade testning är det scenaribaserade tillväga-gångssättet, där intelligenta fordon utsätts för kända scenarier. Identifiering av sådana scenarier från kördata är avgörande för denna validering. Syftet med denna avhandling är att undersöka möjligheten till oövervakad identifiering av körscenarier från kördata. Uppgiften utförs i två huvuddelar. Den första är segmenteringen av tidsseriedrivdata genom att detektera ändringspunkter, följt av klustring av de tidigare erhållna segmenten. Tidsseriesegmentering närmar sig med en Deep Learningmetod, medan den andra uppgiften utförs med hjälp av tidsseriekluster. Arbetet innehåller också ett visuellt tillvägagångssätt för att validera tidsserierna, följt av ett kvantitativt mått på prestanda. Tillvägagångssättet jämförs också med en Bayesian icke-parametrisk metod för att identifiera användbarheten av den föreslagna metoden. Baserat på analysen av resultaten diskuteras metodens användbarhet och nackdelar, följt av möjligheten för framtida forskning.
112

Autonomous Landing of a UAV ona Moving UGV Platform using Cooperative MPC

Garegnani, Luca January 2021 (has links)
Cooperative control of autonomous multi-agent systems is a research areawhich is getting significant attention in recent years. Multi-agent systemsallow for a broad spectrum of applications and cooperation can increasetheir flexibility, efficiency and robustness to changes in external constraintsand disturbances. Focusing on autonomous vehicles, examples of possibleapplications of cooperative multi-agent systems include search and rescuemissions, autonomous delivery and performing of emergency landings.The purpose of the thesis is to develop and implement a cooperativerendezvous algorithm based on model predictive control and apply it to theproblem of autonomous landing in an indoor setting. The agents involved in themaneuver are a quadcopter and a ground carrier. The two agents cooperativelynegotiate on the optimal location for the touchdown taking also into accountrelevant spatial constraints and, if necessary, update that location, also referredto as rendezvous point, in real-time throughout the maneuver.The algorithm is first tested and validated in a simulated environment andfinally on the physical system during real-time operations.Additional scenarios are tested in the simulated environment in order tofurther inspect the potential capabilities of the developed algorithm. Thoseadditional simulations analyse how the algorithm behaves when a constantlateral wind influences the quadcopter; when the controllers operate at areduced frequency; and when the quadcopter is affected by an external Gaussiandisturbance.The developed algorithm proved to be suitable for the purpose, allowingthe agents to perform the desired maneuver in a relatively short time and witha high degree of precision. / Kooperativ reglering av autonoma fleragentsystem är ett forskningsområdesom har fått stor uppmärksamhet de senaste åren. Fleragentsystem möjliggörett brett spektrum av applikationer samtidigt som kooperation kan öka derasflexibilitet, effektivitet och robusthet mot förändringar i yttre begränsningar ochstörningar. Med fokus på autonoma fordon, exempel på möjliga tillämpningarav kooperativa fleragentsystem inkluderar sök- och räddningsuppdrag, autonomleverans och utförande av nödlandningar.Syftet med rapporten är att utveckla och implementera en kooperativrendezvous -algoritm baserad på modellprediktiv reglerteknik samt att tillämpaden för att utföra en inomhus autonom landning. I vår uppställning beståragenterna i manövern av en quadcopter och en markbärare. De två agenternaförhandlar samarbetsvilligt om den optimala platsen för landning samtidigtsom de beaktar relevanta rumsliga begränsningar och uppdaterar vid behovden platsen i realtid under hela manövern.Algoritmen testas och valideras först i en simulerad miljö och slutligen pådet fysiska systemet under en realtidsmiljö.Ytterligare scenarier testas i den simulerade miljön för att bortre inspekterapotentialen hos den utvecklade algoritmen. Dessa extra simuleringar illustrerarhur algoritmen beter sig när en konstant sidovind påverkar quadcoptern; närstyrenheterna arbetar med reducerad frekvens; och när quadcoptern påverkasav en yttre Gaussisk störning.Den utvecklade algoritmen visade sig vara lämplig för ändamålet, vilketgjorde att agenterna kunde utföra önskad manöver på relativt kort tid och medhög precision.
113

Frihetens rike : Wikipedianer om sin praktik, sitt produktionssätt och kapitalismen

Lund, Arwid January 2015 (has links)
This study is about voluntary productive activities in digital networks and on digital platforms that often are described as pleasur­able. The aim of the study is to relate the peer producers’ perceptions of their activities on a micro level in terms of play, game, work and labour, to their views on Wikipedia’s relation to capitalism on a macro level, to compare the identified ideological formations on both levels and how they relate to each other, and finally compare the identi­fied ideological formations with contemporary Marxist theory on cognitive capitalism. The intention is to perform a critical evaluation of the economic role of peer production in society.Qualitative and semi-structured interviews with eight Wikipedians active within the Swedish language version of Wikipedia con­stitute the empirical base of the study together with one public lecture by a Wikipedian on the encyclopaedia and a selection of pages in the encyclopaedia that are text analysed. The transcribed interviews have been analysed using a version of ideological analysis as it has been developed by the Gothenburg School. The views on the peer producing activities on the micro level has been analysed in a dialecti­cal way but is also grounded in a specific field model.Six ideological formations are identified in the empirical material. On the micro level: the peripheral, bottom-up- and top-down-formation, on the macro level: the Californian alikeness ideology, communism of capital and capitalism of communism. Communism of capital has two sides to it: one stresses the synergies and the other the conflicts between the two phenomena. The formations on the macro level conform broadly to contemporary Marxist theory, but there are important differ­ences as well. The study results in a hypothesis that the critical side of communism of capital and the peripheral and bottom-up-formation could help to further a more sustainable capitalism of communism, and counteract a deeper integra­tion of the top-down-formation with Californian alikeness ideology. The latter is the main risk of capitalist co-optation of the peer produc­tion that is underway as the manifestly dominant formations on the macro level are Californian alikeness ideology and communism of capital. / <p>©<strong> </strong>2015 Arwid Lund, used under a Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 license: http://creativecommons.org/licenses/by-nc-nd/3.0/</p><p></p>
114

Ausgewählte Konzepte des selbstbestimmten Lernens.

Günther, Susann 12 December 2013 (has links) (PDF)
Die Idee der Selbstbestimmung ist ein Konzept, welchem im historischen sowie aktuellen pädagogischen Diskurs eine hohe Bedeutung zugemessen wird. Ausgehend von der Epoche der Aufklärung wird der Mensch als vernunftbegabtes Wesen mit der Fähigkeit zum selbstbestimmten Handeln verstanden. Gleichzeitig hat sich, mit Beginn der Pädagogik als Wissenschaft, aus dem theoretisch und praktisch scheinbar nicht zu lösenden, Widerspruch zwischen subjektiver Autonomie und intentionaler Heteronomie ein Problem aufgetan, dessen Lösungsversuche den erziehungswissenschaftlichen Diskurs bis heute prägen. Wird dem Kind die Fähigkeit und das Recht auf selbstbestimmtes Handeln ausdrücklich anerkannt, ist jede pädagogische Intervention als fremdbestimmt abzulehnen. Dies würde im schlimmsten Fall bedeuten, dass die Erziehung sich selbst abschafft. Wenn man Autonomie allerdings als Kompetenz versteht, die am Ziel eines Entwicklungsprozesses steht, stellt sich die Frage ob ein Mensch ohne Erziehung überhaupt in diesen Zustand gelangen kann. Vor dem Hintergrund des Selbstbestimmungsdiskurses, des pädagogischen Paradox, der Bindungstheorie und lernpsychologischer Ansätze, wird in der Arbeit der Frage nachgegangen, ob und inwiefern Schüler, denen aktuell keine oder nur wenige Teilkompetenzen für selbstbestimmtes Lernen zugeschrieben werden, selbstbestimmt lernen können.
115

Catalytic Tubular Micro-Jet Engines

Solovev, Alexander Alexandrovich 26 June 2012 (has links)
This dissertation offers demonstrations of autonomous catalytic microtubes (microjet engines) with tunable diameters ranging from micro- to nanoscale and lengths from 50 μm to 1 mm. These results open the door to effective microengines and represent the entry in the Guinness Book of World Records for “the smallest man-made jet engine.” Several attractive methodologies of machine-based functions at the micro- and nanoscale are shown. For instance, catalytic Ti/Cr/Pt microjets, which are integrated on a planar substrate, can operate as “on chip” chemical micropumps by decomposition of hydrogen peroxide fuel into oxygen bubbles and water. When released from a substrate, microjets self-propel autonomously in solution. The incorporation of ferromagnetic layer (Fe) into the rolled-up geometry enables their remote control using external magnetic field. Such microjets were used to load, transport, deliver and assemble multiple cargo particles, including biological cells in bulk solutions and microfluidic channels. Furthermore, it is demonstrated that for microjets that are fixed to or self-propelled above a platinum patterned surface, the microengine power/speed can be controlled using a white lightsource. A change in intensity of the white light leads to a controllable switching “off” and “on” of the microengine power on demand. Light degrades a local concentration of the hydrogen peroxide fuel and surface tension and subsequently suppresses the generation of oxygen microbubbles. In the next step, the diameter of the microjets was rigorously reduced to 250 nm by using hybrid heteroepitaxial/catalytic InGaAs/GaAs/Cr/Pt nanotubes. Due to asymmetry of the rolled-up layers, these nanojets move in corkscrew-like motions and act as “self-propelled nanotools,” which were used in the next step to transport yeast cells and drill into fixed cancer Hela cells. Although it is well-known that hydrogen peroxide cannot be used to sustain viable cellular function, it is however conceivable that alternative fuels, such as glucose, might enable operation of such nanotools under biologically compatible conditions. As a first step to achieve this goal, demonstrations were made using metal-enzyme biocatalytic Ti/Au/SAM/Catalase microengines. Synthetic components with competing interactions are well-suited to study the emergence of their collective behavior, such as swarms of large numbers of individuals. Microengines’ self-organization in bistable swarms is shown at the air-liquid interface of the mixture of propylene carbonate and hydrogen peroxide. Microengines act as “water striders.” Buoyed by oxygen bubbles, they self-propel via the microbubble recoiling mechanism and, depending on the bubbles’ sizes, self-organize into swarms due to the meniscus climbing effect. These reversible swarms depend on the microengine power, which competes against attracting surface tension force. The demonstrated microjet engines show great promise for emerging applications, including biomedical, on-chip, environmental, and robotic micromachines. Furthermore, a key method discovered, entitled “rolled-up nanotechnology on polymers,” allowed for the fabrication of highly parallel arrays of microtubes with multiple functionalities and aimed for different purposes.
116

Exploring the Training Data for Online Learning of Autonomous Driving in a Simulated Environment

Kindstedt, Mathias January 2020 (has links)
The field of autonomous driving is as active as it has ever been, but the reality where an autonomous vehicle can drive on all roads is currently decades away. Instead, using an on-the-fly learning method, such as qHebb learning, a system can,after some demonstration, learn the appearance of any road and take over the steering wheel. By training in a simulator, the amount and variation of training can increase substantially, however, an on-rails auto-pilot does not sufficiently populate the learning space of such a model. This study aims to explore concepts that can increase the variance in the training data whilst the vehicle trains online. Three computationally light concepts are proposed that each manages to result in a model that can navigate through a simple environment, thus performing better than a model trained solely on the auto-pilot. The most noteworthy approach uses multiple thresholds to detect when the vehicle deviates too much and replicates the action of a human correcting its trajectory. After training on less than 300 frames, a vehicle successfully completed the full test environment using this method. / Autonom körning är ett aktivt område inom både industrin och forskarvärlden, men ännu är en verklighet där förarlösa fordon kan ta sig fram oavsett väg, decennier bort. Istället kan man genom att använda en adaptiv inlärningsmodell som qHebb learning uppnå ett system som kan ta sig fram självmant på alla vägar, efter en initial inlärningsperiod. Genom att använda en simulator skulle möjligheten att träna en sådan modell öka avsevärt, likaså variationen av vägtyper och det omgivande landskapet. Dock klarar inte en enformig autopilot att fylla modellens lärningsrymd. Detta arbete stävar efter att utforska koncept som kan öka variationen på träningsdatan, medan fordonet kör. Tre prestandalätta metoder presenteras som alla överträffar autopiloten och resulterar i en modell som lärt sig att följa en väg längs kurvor och raksträckor. Det främsta konceptet använder sig av två tröskelvärden för att korrigera fordonets styrning då den avviker för mycket från den korrekta rutten. Efter träning på färre än 300 bilder lyckas denna metod slutföra alla testsegment utan kollision.
117

Ausgewählte Konzepte des selbstbestimmten Lernens.: Schlussfolgerungen für den Förderschwerpunkt Lernen.

Günther, Susann 25 June 2013 (has links)
Die Idee der Selbstbestimmung ist ein Konzept, welchem im historischen sowie aktuellen pädagogischen Diskurs eine hohe Bedeutung zugemessen wird. Ausgehend von der Epoche der Aufklärung wird der Mensch als vernunftbegabtes Wesen mit der Fähigkeit zum selbstbestimmten Handeln verstanden. Gleichzeitig hat sich, mit Beginn der Pädagogik als Wissenschaft, aus dem theoretisch und praktisch scheinbar nicht zu lösenden, Widerspruch zwischen subjektiver Autonomie und intentionaler Heteronomie ein Problem aufgetan, dessen Lösungsversuche den erziehungswissenschaftlichen Diskurs bis heute prägen. Wird dem Kind die Fähigkeit und das Recht auf selbstbestimmtes Handeln ausdrücklich anerkannt, ist jede pädagogische Intervention als fremdbestimmt abzulehnen. Dies würde im schlimmsten Fall bedeuten, dass die Erziehung sich selbst abschafft. Wenn man Autonomie allerdings als Kompetenz versteht, die am Ziel eines Entwicklungsprozesses steht, stellt sich die Frage ob ein Mensch ohne Erziehung überhaupt in diesen Zustand gelangen kann. Vor dem Hintergrund des Selbstbestimmungsdiskurses, des pädagogischen Paradox, der Bindungstheorie und lernpsychologischer Ansätze, wird in der Arbeit der Frage nachgegangen, ob und inwiefern Schüler, denen aktuell keine oder nur wenige Teilkompetenzen für selbstbestimmtes Lernen zugeschrieben werden, selbstbestimmt lernen können.:1 Einleitung I Der Selbstbestimmungsgedanke 2 Etymologische Einordnung 3 Autonomie aus philosophischer Sicht 3.1 Autonomie als Selbstgesetzgebung in der Moralethik Kants 3.2 Autonomie als moralisches Ziel 3.3 Das Recht auf selbstbestimmtes Handeln 4 Die Pädagogik der Selbstbestimmung im Diskurs 4.1 Das pädagogische Paradox 4.2 Von Selbstbestimmung als Erziehungsziel zur Selbstbestimmung als Erziehungsnotwendigkeit 4.2.1 Das klassisch kantische Modell der Erziehung 4.2.2 Der Umbruch 4.2.3 Das Kind als Akteur seiner eigenen Entwicklung 4.3 Schlussfolgerungen und Kritik an einem perfektiblen Menschenbild 5 Selbstbestimmung vs. Angewiesensein? 5.1 Die Bindungstheorie 5.2 Die Komplementarität von Autonomie und Angewiesensein 5.3 Bindung und kognitive Entwicklung II Selbstbestimmtes Lernen 6 Begriffsklärung 6.1 Selbstbestimmtes Lernen 6.2 Selbstgesteuertes Lernen 7 Voraussetzungen selbstbestimmten Lernens aus lernpsychologischer Sicht 7.1 Selbstgesteuertes Lernen bei Neber 7.2 Selbstbestimmungstheorie der Motivation von Deci & Ryan 7.3 Boekaerts‘ drei Schichten der Selbstregulation 7.4 Das INVO-Modell von Hasselhorn & Gold 7.4.1 Kognitive Voraussetzungen 7.4.2 Motivational-volitionale Voraussetzungen 8 Zusammenführung 9 Grenzen des Kognitivismus‘ III Selbstbestimmung und Förderschwerpunkt Lernen 10 Voraussetzungen selbstbestimmten Lernens im Kontext von Beeinträchtigungen im Lernen 11 Andere Sichtweisen auf das Phänomen Lernbeeinträchtigung 12 Fazit: Inklusion IV Ableitende Kerngedanken zum selbstbestimmten Lernen 13 Selbstbestimmung als Kompetenz 14 Rahmenbedingungen selbstbestimmten Lernens 14.1 Unterricht 14.2 Lernumwelt 14.3 Lehrerverhalten 15 Schlussbetrachtung Literaturverzeichnis Darstellungsverzeichnis
118

Deep Reinforcement Learning for Autonomous Highway Driving Scenario

Pradhan, Neil January 2021 (has links)
We present an autonomous driving agent on a simulated highway driving scenario with vehicles such as cars and trucks moving with stochastically variable velocity profiles. The focus of the simulated environment is to test tactical decision making in highway driving scenarios. When an agent (vehicle) maintains an optimal range of velocity it is beneficial both in terms of energy efficiency and greener environment. In order to maintain an optimal range of velocity, in this thesis work I proposed two novel reward structures: (a) gaussian reward structure and (b) exponential rise and fall reward structure. I trained respectively two deep reinforcement learning agents to study their differences and evaluate their performance based on a set of parameters that are most relevant in highway driving scenarios. The algorithm implemented in this thesis work is double-dueling deep-Q-network with prioritized experience replay buffer. Experiments were performed by adding noise to the inputs, simulating Partially Observable Markov Decision Process in order to obtain reliability comparison between different reward structures. Velocity occupancy grid was found to be better than binary occupancy grid as input for the algorithm. Furthermore, methodology for generating fuel efficient policies has been discussed and demonstrated with an example. / Vi presenterar ett autonomt körföretag på ett simulerat motorvägsscenario med fordon som bilar och lastbilar som rör sig med stokastiskt variabla hastighetsprofiler. Fokus för den simulerade miljön är att testa taktiskt beslutsfattande i motorvägsscenarier. När en agent (fordon) upprätthåller ett optimalt hastighetsområde är det fördelaktigt både när det gäller energieffektivitet och grönare miljö. För att upprätthålla ett optimalt hastighetsområde föreslog jag i detta avhandlingsarbete två nya belöningsstrukturer: (a) gaussisk belöningsstruktur och (b) exponentiell uppgång och nedgång belöningsstruktur. Jag utbildade respektive två djupförstärkande inlärningsagenter för att studera deras skillnader och utvärdera deras prestanda baserat på en uppsättning parametrar som är mest relevanta i motorvägsscenarier. Algoritmen som implementeras i detta avhandlingsarbete är dubbel-duell djupt Q- nätverk med prioriterad återuppspelningsbuffert. Experiment utfördes genom att lägga till brus i ingångarna, simulera delvis observerbar Markov-beslutsprocess för att erhålla tillförlitlighetsjämförelse mellan olika belöningsstrukturer. Hastighetsbeläggningsgaller visade sig vara bättre än binärt beläggningsgaller som inmatning för algoritmen. Dessutom har metodik för att generera bränsleeffektiv politik diskuterats och demonstrerats med ett exempel.
119

Modelling closed-loop receptive fields: On the formation and utility of receptive fields in closed-loop behavioural systems / Entwicklung rezeptiver Felder in autonom handelnden, rückgekoppelten Systemen

Kulvicius, Tomas 20 April 2010 (has links)
No description available.
120

Frihetens rike : Wikipedianer om sin praktik, sitt produktionssätt och kapitalismen

Lund, Arwid January 2015 (has links)
This study is about voluntary productive activities in digital networks and on digital platforms that often are described as pleasur­able. The aim of the study is to relate the peer producers’ perceptions of their activities on a micro level in terms of play, game, work and labour, to their views on Wikipedia’s relation to capitalism on a macro level, to compare the identified ideological formations on both levels and how they relate to each other, and finally compare the identi­fied ideological formations with contemporary Marxist theory on cognitive capitalism. The intention is to perform a critical evaluation of the economic role of peer production in society.Qualitative and semi-structured interviews with eight Wikipedians active within the Swedish language version of Wikipedia con­stitute the empirical base of the study together with one public lecture by a Wikipedian on the encyclopaedia and a selection of pages in the encyclopaedia that are text analysed. The transcribed interviews have been analysed using a version of ideological analysis as it has been developed by the Gothenburg School. The views on the peer producing activities on the micro level has been analysed in a dialecti­cal way but is also grounded in a specific field model.Six ideological formations are identified in the empirical material. On the micro level: the peripheral, bottom-up- and top-down-formation, on the macro level: the Californian alikeness ideology, communism of capital and capitalism of communism. Communism of capital has two sides to it: one stresses the synergies and the other the conflicts between the two phenomena. The formations on the macro level conform broadly to contemporary Marxist theory, but there are important differ­ences as well. The study results in a hypothesis that the critical side of communism of capital and the peripheral and bottom-up-formation could help to further a more sustainable capitalism of communism, and counteract a deeper integra­tion of the top-down-formation with Californian alikeness ideology. The latter is the main risk of capitalist co-optation of the peer produc­tion that is underway as the manifestly dominant formations on the macro level are Californian alikeness ideology and communism of capital. / <p>©<strong> </strong>2015 Arwid Lund, used under a Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 license: http://creativecommons.org/licenses/by-nc-nd/3.0/</p><p></p>

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