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Autonomous Spacecraft Mission Planning And Execution In A Petri Net FrameworkIndra, A 07 1900 (has links) (PDF)
Presently, most spacecraft are controlled from ground involving activities such as up-linking the schedule of daily operations and monitoring health parameters. These activities lead to a cognitive overload on human operators. Imaging/science opportunities are lost, if any discrepancies occur during the execution of pre-planned sequences. Consequently, advanced space exploration systems for future needs demand on-board intelligence and autonomy. This thesis attempts to solve the problem of providing an adequate degree of autonomy in future generation of spacecraft. The autonomous spacecraft accept high-level goals from users and make decisions on-board to generate detailed command schedules satisfying stringent constraints posed by the harsh environment of the space, visibility criteria and scarce on-board resources. They reconfigure themselves in case of any failure and re-plan when needed.
Autonomy concepts are derived in the context of complex systems by drawing analogy to living organisms and social organisations. A general autonomy framework may be defined with a six level structure comprising of the following capabilities -reflexes, awareness, self-regulation, self-healing, self-adaptation and self-evolution. A generic and reusable software architecture is proposed using hybrid multi-agent systems, which are arranged in a hierarchical manner using two types of decomposition viz. stratum and layer. The software architecture of the autonomous spacecraft is modeled as a stratified agent with a deliberative stratum, which achieves adaptive behaviour and a reactive stratum, which achieves reactive behaviour. Each individual agent has a generic structure comprising of perception, action, communication and knowledge components. It achieves the specialist capability through model-based reasoning. The knowledge models encompass: Planning knowledge describing higher-level goals, task structure and method of achieving the goals, Control knowledge encompassing the static and dynamic models of the spacecraft and Diagnostic knowledge incorporating the cause-effect relationships. The deliberative stratum is capable of planning in different time horizons and is, in turn, organised into a hierarchical agent system with three layers corresponding to different time horizons. It is composed of a long-term, medium-term and short-term planning agents, focusing on strategic issues, spacecraft level resources and specific spacecraft states respectively.
The power of Petri nets is exploited for knowledge modeling as well as for plan representation. The ability of Petri nets to represent causality, concurrency and conflict relations explicitly makes it an excellent tool for representing the planning problem. Hierarchical Timed Petri Net is chosen for our modeling, since it captures the temporal requirements of the real-time spacecraft operations as well as facilitates the modeling of the system with multiple levels of abstraction. The necessary primitives for the plan representation are defined. In hierarchical modeling using Petri nets, refinement is done by a compound (high-level) transition. A compound transition models either a complex activity, which corresponds to high-level operation on spacecraft or a method, which corresponds to the agent capability. At the lowest layer, a transition in the plan represents a primitive command to the spacecraft, such as ‘switch on camera’. The Petri net unfolding technique, which is a partial order approach, is applied to derive the plans from the dynamic knowledge models. This tackles the problem of combinatorial explosion. A hierarchical planning approach is followed, in which the abstract plan is recursively decomposed using the unfolding technique and refined by way of exercising the appropriate decisions in each layer. The reactive stratum is configured with three peer level agents. The control agent executes the command schedule and has the capability for reflex action. Structural properties of Petri nets are exploited by the execution-monitoring agent and the diagnostic agent for system level diagnosis. Fault tree method is applied for fine granularity diagnosis. The resultant architecture is a cost-effective solution, since it permits reusability of knowledge models across similar missions.
The knowledge models are formally verified for ensuring the absence of deadlocks, buffer overflows, recoverability and detection of unreachable modules using Petri net properties such as reachability, liveness, boundedness, safeness, reversibility and home state. The high-risk components are subjected to safety property verification, which makes the system rugged. The hierarchical composition of Petri net models (which are independently verified), preserves liveness and boundedness characteristics and thus ensuring the reliability of the integrated models. This, in turn, ensures that reliable plans are generated on-board using these good quality models. The models of the system components viz. partial order plan, conditional plan, dynamic world model, reflex model, resource model and the hierarchical models are developed and demonstrated using HPSIM and Moses Tool Suite, using examples from spacecraft domain. The long-term planning agent, with hierarchical world models, for handling high-level goals is developed and simulated using Moses Tool Suite. The plan generation using unfolding approach is demonstrated using VIPTool, which has the partial order analysis capability.
In summary, the main contributions include (a) Definition of a general framework for spacecraft autonomy; (b) design of a generic and reusable architecture for autonomous spacecraft using hybrid multi-agent concepts; (c) unified knowledge representation and reasoning using Petri nets across various strata/layers; (d) application of Petri net unfolding technique in a hierarchical manner for plan generation; (e) use of structural properties of Petri nets for fault identification and location; (f) verification and validation of Petri net models using Petri net properties and (g) simulation and demonstration of the system components viz. partial order plan, conditional plan, dynamic world model, reflex model, resource model and hierarchical models, by developing examples from spacecraft domain, using HPSIM and Moses Tool Suite and demonstration of plan generation using unfolding technique using VIPTool.
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Die kooperative Promotion im Doktorandennetzwerk DOK.NETClaus, Thorsten 10 October 2014 (has links)
No description available.
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Nástroj pro usnadnění testování GUI webových aplikací / Productivity Tool for Web Application TestingKalous, Filip January 2019 (has links)
The goal of this thesis is to create a tool for testing graphical user interface of web applications. The tool will focus on web applications implemented by open-source framework DotVVM. The main purpose of the tool is to automatically generate program description of a user interface which will then be used as a helper class to implement UI tests and for static type check of those tests at compile-time. The thesis is defining requirements for such a tool and describing its design with implementation in C# language. The created solution provides to its users a tool which will ease their work with tests creation. Also, it will bring detection of failing tests of the user interface at compile-time which will speed up testing and development.
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Aplikace nových komunikačních technologií do firemní počítačové sítě / Aplication of New Communication Technologies into Company´s Computer NetworkŠafránek, Filip January 2009 (has links)
The target of master's thesis is implementation solution of communication VoIP technologies and connection recording system and CRM system in order to saving costs for company INTERNET TRADING s.r.o..
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Náhrada parovodu horkovodem v systému centrálního zásobování teplem teplárny Martinská teplárenská, a.s / Substitution of steam by hot water in heat distribution netMužila, Martin January 2014 (has links)
The work is focused on area of exchanging steam distribution net for hot water one, in central distribution net of Martin’s heating plant. The main subject, which talks about pros and cons in this exchange process, is determination of heat losses which are created on heat distribution net during different operating status. These heat losses are calculated and on their basis some conclusions are concluded. Moreover, new heat exchanger is designed for certain conditions and also mathematical model of distribution net is created, which is suitable for checking different operating status. As a result of the work is technic’s and economic’s analysis of this project.
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Distribuovaný informační systém malé firmy / Distributed Information System for a Small FirmPajgrt, Ondřej January 2010 (has links)
This thesis deals with implementation of distributed information systém for a small construction engineering firm all the way from design to deployment. We will be introduced to distributed applications problems and technologies involved either throught direct relevance or as a support tool for the implementation of the project. In addition, this work will guide us throught complete design and implementation of a final product.
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Silná kryptografie na čipových kartách / Strong Cryptography on Smart CardsKonečný, Jakub January 2017 (has links)
The diploma thesis is focused on cryptography with smart cards. It describes smart cards from hardware and software side. The thesis compares well known operating systems used on smart cards. Specified operating systems are widely analyzed. There is introduction to password authenticated key establishment protocols. PACE protocol is described in details together with implementation proposal. The implementation on the Basic card platform follows. In the end there is the time analysis of the implementation and further improvements are suggested.
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Virtual Collaborative Learning: Auf der Suche nach den Digital NativesSchoop, Eric, Lieske, Claudia, Bukvova, Helena 20 January 2010 (has links)
Dieser Beitrag untersucht die These über die Existenz von Digital Natives. Die Vertreter dieser These postulieren, dass Studenten und Schüler durch den frühen Kontakt mit Informations- und Kommunikationstechnologien hinsichtlich ihres Lern-, Arbeits- und Kommunikationsverhaltens wesentlich verändert wurden. Um diese Aussage zu bewerten, werden Erfahrungen mit Virtual Collaborative Learning Veranstaltungen herangezogen. Die aktuellste durchgeführte Veranstaltung wird als Fallstudie vorgestellt und analysiert.
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Utilisation de l’habitat par le chevreuil (Capreolus capreolus) dans des environnements variables et contrastés / Roe deer (Capreolus capreolus) habitat use in various different environmental conditionsGaudry, William 18 December 2015 (has links)
Au sein de son aire de répartition, le chevreuil (Capreolus capreolus) rencontre des conditions environnementales variables et contrastées qui engendrent une grande variété de patrons d'utilisation de l'espace. Jusqu'à présent, aucune étude n'a clairement établi un lien entre les différents patrons d'utilisation de l'espace et les conditions environnementales dans lesquelles le chevreuil évolue, ce qui limite notre compréhension des mécanismes impliqués dans le processus de sélection d'habitat. Grâce aux suivis télémétriques de nombreux chevreuils dans 4 sites avec des conditions environnementales fortement variables et contrastées nous avons cherché à établir un lien entre les variations des conditions environnementales et les variations des patrons d'utilisation de l'espace. Ainsi, nous avons démontré qu'en milieu alpin, les chevreuils adaptent l'amplitude de leurs déplacements en fonction des variations spatiales et temporelles de la disponibilité des ressources ainsi qu'en fonction des conditions d'enneigement. Contrairement aux précédentes études sur l'utilisation de l'espace par le chevreuil en milieu de montagne, nous avons montré que les mouvements des chevreuils au sein de notre aire d'étude correspondaient à un processus de sélection d'habitat de troisième ordre (48 cas; 89%) plutôt qu'à de la migration partielle, puisque très peu d'individus (6 cas; 11%) avaient stabilisé leurs déplacements au sein de domaines vitaux distincts au cours des saisons. Par ailleurs, nous avons démontré que le comportement de sélection d'habitat des chevreuils à l'échelle du domaine vital était très variable entre les populations mais également au sein de chaque population. Ainsi dans les forêts les plus pauvres où les ressources sont spatialement séparées au sein de différents habitats, nous avons démontré que les chevreuils étaient contraints de réaliser des compromis, générant des réponses fonctionnelles en sélection d'habitat. Au contraire, dans les habitats les plus riches où les ressources sont disponibles dans toutes les catégories d'habitat, nous n'avons pas observé de réponse fonctionnelle puisque les chevreuils n'étaient pas contraints et donc ne réalisaient pas de compromis. De plus, nous avons démontré que les chevreuils avec une même composition de domaine vital dans différents sites, utilisaient les ressources différemment. Ces résultats démontrent que la façon dont une ressource est utilisée ne dépend pas seulement de son niveau de disponibilité au sein du domaine vital mais varie également en fonction des conditions environnementales. De ce fait, il est impératif de tenir compte des conditions environnementales au sein d'un site pour mieux comprendre les mécanismes impliqués dans l'émergence des différents patrons d'utilisation de l'espace observés chez les ongulés. Enfin, nous avons tenté d'établir un lien entre les variations observées dans les patrons de sélection d'habitat à différentes échelles et la valeur sélective des chevreuils dans les populations de Chizé et de Trois-Fontaines pour lesquelles les données requises étaient disponibles, mais nous n'avons pu mettre en évidence aucun effet du comportement de sélection d'habitat sur la valeur sélective individuelle des femelles / Across its distributional range, the European roe deer (Capreolus capreolus) encounters a wide range of environmental conditions that generate marked differences of space use patterns. However, linking variation in space use by animals in different populations facing contrasted environmental conditions to site-specific conditions has not yet been investigated, which currently limits our understanding of the mechanisms involved in habitat selection. Using data collected on roe deer equiped with VHF and GPS collars in four different sites with contrasted environmental conditions, we aimed to fill this knowledge gap by relating variations in space use by animals in variable environmental conditions. We found that roe deer in Alpine environment adapt the magnitude of their movements to the spatial and temporal variation in resource availability, but also to the amount of snow cover. Contrary to previous studies on roe deer performed in mountain ranges, we showed that roe deer movements in the northern French Alps corresponds to the usage of various habitat components within the home range (third order habitat selection process; 48 cases; 89%) rather than as partial migration because very few (6 cases; 11%) roe deer stabilized their activity in distinct home ranges across seasons. Moreover, we found that roe deer markedly differed in habitat selection within their home range, both within and among populations. Roe deer facing poor environmental conditions with spatially segregated resources should trade one resource for another one, which generates a functional response in habitat selection. At the opposite, roe deer benefiting from rich environmental conditions in their home range do not have to trade one resource for another one and therefore did not display any functional response. In addition, our results suggest that a same habitat composition can lead to widely different space use patterns. These findings demonstrate that the way a given habitat type is used in relation to its availability strongly varies in response to environmental conditions, so that accounting for variation in environmental conditions is required to provide a reliable assessment of the mechanisms involved to shape the diversity of space use patterns we currently observed in ungulates. Finally, we looked for linking observed variation in space use patterns to indivudual fitness of female roe deer in the populations of Chizé and Trois-Fontaines for which the required data were available. However, we did not find any evidence of a positive effect of the intensity of habitat selection on individual female fitness
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SharePoint apps / SharePoint AppsHaddad, Elias, Abdelke, Dany January 2013 (has links)
Microsoft SharePoint 2013 är en plattform som är väldigt populär för utveckling av intranät. Möjligheterna för kommunikation inom en organisation bidrar till större och bättre informationsflöde inom organisationen samt leder till effektivare arbete inom organisationen. Microsoft Sharepoint 2013 är alltså ett intranät som blir ett centrum att vistas på samt där man träffar sina kollegor för att dela information och mycket mer. Detta examensarbete utgår från Microsofts välkända intranät Sharepoint 2013. Målet med examensarbetet har varit att skapa ett ärendehanteringssystem utifrån företaget Precio Systemutveckling AB:s beställning samt kravspecifikation . Utvecklingen har baserats på ”The great new app model” som under början på detta år (2013) introducerades utav Microsoft i den senaste versionen av Sharepoint: Sharepoint 2013. Det finns flera olika utvecklingsmetoder för att utveckla i appmodellen. Efter en utförd förstudie valdes ”Provider hosted app”, vilket innebär att ärendehanteringssystemet skall utvecklas samt köras på en server som företaget ansvarar över. Då appmodellen är relativt ny så har det under projektets gång uppstått utmaningar som varit riktigt kluriga att lösa på grund av att man inte lyckats finna relevanta källor med förklaring på de olika problem som uppstod. Utmaningarna har ändå lösts med hjälp av den information som idag finns samt med stöd ifrån seniora Sharepoint utvecklare. Resultatet av detta projekt blev ett ärendehanteringssystem som levererats till företaget samt som eventuellt kommer att börja användas inom kort. Förstudien kring appmodellen har även lett till ökade kunskaper kring hur appar i Sharepoint fungerar samt dess styrkor och svagheter. / This project is about apps in Microsoft Sharepoint 2013. We are two students that will during this thesis create a task management system for the company Precio Systemutveckling AB. We will use the great new app model that is a way to develop Sharepoint apps. The result of this project is a task management system that the company can use to keep track of their tasks.
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