004 Datenverarbeitung; Informatik
Refine
Has Fulltext
- yes (80)
Is part of the Bibliography
- yes (80)
Year of publication
Document Type
- Doctoral Thesis (80) (remove)
Keywords
- Leistungsbewertung (13)
- Robotik (8)
- Mobiler Roboter (7)
- Autonomer Roboter (6)
- Komplexitätstheorie (5)
- Netzwerk (5)
- Optimierung (5)
- Simulation (5)
- Theoretische Informatik (5)
- Modellierung (4)
- Optimization (4)
- Overlay-Netz (4)
- Routing (4)
- Verteiltes System (4)
- Algorithmus (3)
- Approximationsalgorithmus (3)
- Computer Vision (3)
- Computersimulation (3)
- Dienstgüte (3)
- Drahtloses Sensorsystem (3)
- Graph (3)
- Graphenzeichnen (3)
- Komplexität (3)
- Lokalisation (3)
- Machine Learning (3)
- Maschinelles Lernen (3)
- Mensch-Maschine-Schnittstelle (3)
- Netzwerkmanagement (3)
- Peer-to-Peer-Netz (3)
- Performance Evaluation (3)
- graph drawing (3)
- Algorithmische Geometrie (2)
- Ausfallsicheres System (2)
- Ausfallsicherheit (2)
- Benutzerschnittstelle (2)
- Data Mining (2)
- Dot-Depth Problem (2)
- Drahtloses lokales Netz (2)
- Effizienter Algorithmus (2)
- Entscheidbarkeit (2)
- Fernwartung (2)
- Future Internet (2)
- Human-Robot-Interaction (2)
- IEEE 802.11 (2)
- Kleinsatellit (2)
- Kreuzung (2)
- Localization (2)
- Maschinelles Sehen (2)
- Mehragentensystem (2)
- Mensch-Maschine-System (2)
- Mensch-Roboter-Interaktion (2)
- Mixed Reality (2)
- PROLOG <Programmiersprache> (2)
- Punktwolke (2)
- QoE (2)
- Quality of Experience (2)
- Rechnernetz (2)
- Resilience (2)
- Resource Management (2)
- Ressourcenmanagement (2)
- Robotics (2)
- Satellit (2)
- Situation Awareness (2)
- Software Defined Networking (2)
- Teleoperation (2)
- Theoretical Computer Science (2)
- User Interface (2)
- Verbotsmuster (2)
- approximation algorithm (2)
- decidability (2)
- dot-depth problem (2)
- endliche Automaten (2)
- finite automata (2)
- forbidden patterns (2)
- knowledge representation (2)
- mobile robots (2)
- regular languages (2)
- reguläre Sprachen (2)
- simulation (2)
- 3D Pointcloud (1)
- 3D Punktwolke (1)
- 3D Reconstruction (1)
- 3D Sensor (1)
- 3D Vision (1)
- 3D point cloud (1)
- 3D thermal mapping (1)
- 3D-Rekonstruktion (1)
- 4G Networks (1)
- 6DOF Pose Estimation (1)
- Abhängigskeitsgraph (1)
- Ablaufplanung (1)
- Admission Control (1)
- Agent <Informatik> (1)
- Agent <Künstliche Intelligenz> (1)
- Agent-based Simulation (1)
- Agentbased System (1)
- Agenten-basierte Simulation (1)
- Angewandte Informatik (1)
- Anwendung (1)
- Approximation (1)
- Arctic (1)
- Arterie (1)
- Artery (1)
- Automat <Automatentheorie> (1)
- Automata Theory (1)
- Automatentheorie (1)
- Autonomer Agent (1)
- Autonomie (1)
- Autonomous Robot (1)
- Autonomous multi-vehicle systems (1)
- Backbone-Netz (1)
- Background Knowledge (1)
- Banks Islands (1)
- Benutzererlebnis (1)
- Benutzerforschung (1)
- Benutzerinteraktion (1)
- Berechenbarkeit (1)
- Berechnungskomplexität (1)
- Bernoulli stochastics (1)
- Bernoulli-Raum (1)
- Bernoullische Stochastik (1)
- Bernoullispace (1)
- Betriebssystem (1)
- Bewegungsablauf (1)
- Bewegungskompensation (1)
- Bewegungskoordination (1)
- Bewegungsplanung (1)
- Bildverarbeitung (1)
- Biological Networks (1)
- Bit Parallelität (1)
- BitTorrent (1)
- Bodenstation (1)
- Boolean Grammar (1)
- Boolean equivalence (1)
- Boolean functions (1)
- Boolean hierarchy (1)
- Boolean isomorphism (1)
- Boolesche Funktionen (1)
- Boolesche Grammatik (1)
- Boolesche Hierarchie (1)
- CASE (1)
- Calibration (1)
- Call Graph (1)
- Chord (1)
- Clones (1)
- Cloud Gaming (1)
- Communication Networks (1)
- Complex Systems (1)
- Complexity Theory (1)
- Compression (1)
- Computational Geometry (1)
- Computational complexity (1)
- Computerunterstütztes Lernen (1)
- Content Distribution (1)
- DHT (1)
- Databases (1)
- Datenbanken (1)
- Datenbasis (1)
- Deep Georeferencing (1)
- Deep Learning (1)
- Deep learning (1)
- Dependency Graph (1)
- Design (1)
- Dezentrale Regelung (1)
- Diagnosesystem (1)
- Dichotomy (1)
- Digital Elevation Model (1)
- Diskrete Simulation (1)
- Distributed Space Systems (1)
- Domänenspezifische Sprache (1)
- Dot-Depth-Hierarchie (1)
- Drahtloses vermaschtes Netz (1)
- Dreidimensionale Rekonstruktion (1)
- Dreieck (1)
- Dynamic Environments (1)
- Dynamic Memory Management (1)
- Dynamische Speicherverwaltung (1)
- Echtzeitsystem (1)
- Echzeit (1)
- Edge-based Intelligence (1)
- Eingebettetes System (1)
- Elasticity tensor (1)
- Elastizitätstensor (1)
- Embedded Systems (1)
- Emotion inference (1)
- Emotionserkennung (1)
- Emotionsinterpretation (1)
- Endpoint Mobility (1)
- Energieeffizienz (1)
- Energy efficiency (1)
- Entscheidungsfindung (1)
- Erfüllbarkeitsproblem (1)
- Erweiterte Realität (1)
- Euclidean plane (1)
- Euklidische Ebene (1)
- Expert System (1)
- Expertensystem (1)
- Fahrsimulation (1)
- Fahrsimulator (1)
- Fairness (1)
- Feature Based Registration (1)
- Feature-Matching (1)
- Fehlertoleranz (1)
- Feldprogrammierbare Architekturen (1)
- Fernsteuerung (1)
- Field programmable gate array (1)
- Field-programmable Gate Arrays (1)
- Formale Sprache (1)
- Formation (1)
- Formationsbewegung (1)
- Formmessung (1)
- Forschung (1)
- Funkressourcenverwaltung (1)
- Gastroenterologische Endoskopie (1)
- Gay-Array-Bauelement (1)
- Gefühl (1)
- Generalisierung <Kartografie> (1)
- Generation Problem (1)
- Generierungsproblem (1)
- Genetic Optimization (1)
- Genetische Optimierung (1)
- Georeferenzierung (1)
- Gllobal self-localisation (1)
- Globale Selbstlokalisation (1)
- Graphentheorie (1)
- Ground Station Networks (1)
- H.264 SVC (1)
- H.264/SVC (1)
- HSPA (1)
- Halbordnungen (1)
- Hardware (1)
- Herzkatheter (1)
- Herzkathetereingriff (1)
- Hierarchische Simulation (1)
- Hintergrundwissen (1)
- Historical Maps (1)
- Historische Karte (1)
- Historische Landkarten (1)
- Hospital (1)
- IEEE 802.11e (1)
- IEEE 802.15.4 (1)
- IP (1)
- Image Registration (1)
- Implementierung <Informatik> (1)
- Industrial internet (1)
- Industrie 4.0 (1)
- Inferenz <Künstliche Intelligenz> (1)
- Information Extraction (1)
- Information Retrieval (1)
- Information-Retrieval-System (1)
- Interaktion (1)
- Internet Protokoll (1)
- Invertierte Liste (1)
- Isomorphie (1)
- Itinerare (1)
- Itineraries (1)
- Java <Programmiersprache> (1)
- Java Message Service (1)
- Kademlia (1)
- Kanalzugriff (1)
- Karte (1)
- Kartierung (1)
- Klassendiagramm (1)
- Klassifikation (1)
- Knowledge Discovery (1)
- Knowledge-based Systems Engineering (1)
- Kombinatorik (1)
- Kommunikation (1)
- Kommunikationsnetze (1)
- Komplexes System (1)
- Komplexitätsklasse (1)
- Komplexitätsklasse NP (1)
- Konvexe Zeichnungen (1)
- Konzeptsuche (1)
- Kooperierende mobile Roboter (1)
- Krankenhaus (1)
- Kreuzungsminimierung (1)
- Kryoelektronenmikroskopie (1)
- Kurve (1)
- Künstliche Intelligenz (1)
- Land Cover Classification (1)
- Landkartenbeschriftung (1)
- Landnutzungskartierung (1)
- Laser scanning (1)
- Learning (1)
- Lehre (1)
- Lernen (1)
- Lidar (1)
- Link rate adaptation (1)
- Linkratenanpassung (1)
- Logic Programming (1)
- Logische Programmierung (1)
- MAC (1)
- Mackenzie-River-Delta (1)
- Mathematische Modellierung (1)
- Mathematisches Modell (1)
- Medical Image Analysis (1)
- Medium <Physik> (1)
- Medizin (1)
- Mehrebenensimulation (1)
- Mehrfahrzeugsysteme (1)
- Mehrkriterielle Optimierung (1)
- Mehrpfadübertragung (1)
- Mehrschichtnetze (1)
- Mehrschichtsystem (1)
- Mesh Networks (1)
- Mesh Netze (1)
- Methode (1)
- Middleware (1)
- Miniaturisierung (1)
- Minimally invasive vascular intervention (1)
- Missionsbetrieb (1)
- Mobile Roboter (1)
- Mobiles Internet (1)
- Mobilfunk (1)
- Modellbasierte Diagnose (1)
- Modellierungstechniken (1)
- Modelling (1)
- Modularität (1)
- Motion Planning (1)
- Multi-Agent-Simulation (1)
- Multi-Layer (1)
- Multi-Network Service (1)
- Multi-Netzwerk Dienste (1)
- Multi-Paradigm Programming (1)
- Multi-Paradigm Programming Framework (1)
- Multi-agent system (1)
- Multiagentensimulation (1)
- Multiagentensystem (1)
- Multimedia (1)
- Multipath Transmission (1)
- Mustererkennung (1)
- Mycoplasma pneumoniae (1)
- NP (1)
- NP-Vollständigkeit (1)
- NP-complete sets (1)
- NP-hardness (1)
- NP-hartes Problem (1)
- NP-schweres Problem (1)
- Network Management (1)
- Network Virtualization (1)
- Networks (1)
- Netzplantechnik (1)
- Netzplanung (1)
- Netzwerkplanung (1)
- Netzwerkvirtualisierung (1)
- Newton Methods (1)
- Newton-Verfahren (1)
- Next Generation Networks (1)
- Nichtholonome Fahrzeuge (1)
- Nichtlineare Regelung (1)
- Object Detection (1)
- Object-Oriented Programming (1)
- Objektorientierte Programmierung (1)
- Operator (1)
- Optimale Kontrolle (1)
- Optimierungsproblem (1)
- Optimization on Lie Groups (1)
- Overlay (1)
- Overlay Netzwerke (1)
- Overlay networks (1)
- Overlays (1)
- Panorama Images (1)
- Parameterkalibrierung (1)
- Partition <Mengenlehre> (1)
- Partitionen (1)
- Path Computation Element (1)
- Pattern Recognition (1)
- Peer-to-Peer (1)
- Performance Analysis (1)
- Performance Modeling (1)
- Pfadberechnungselement (1)
- Picosatellite (1)
- Planare Graphen (1)
- Planausführung (1)
- Planung (1)
- Planungssystem (1)
- PolSAR (1)
- Polyeder (1)
- Polypektomie (1)
- Post's Classes (1)
- Postsche Klassen (1)
- Prediction (1)
- Process Optimization (1)
- Programmierbare logische Anordnung (1)
- Prozessoptimierung (1)
- Publish-Subscribe-System (1)
- QoS (1)
- Quality of Experience QoE (1)
- Quality of Service (1)
- Quality-of-Experience (1)
- Quality-of-Service (QoS) (1)
- Quantor (1)
- Radarfernerkundung (1)
- Raumdaten (1)
- Real-Time Operating Systems (1)
- Real-time (1)
- Refactoring (1)
- Regelbasiertes System (1)
- Regelung (1)
- Registration (1)
- Registrierung (1)
- Registrierung <Bildverarbeitung> (1)
- Reguläre Sprache (1)
- Relief <Geografie> (1)
- Rendezvous (1)
- Ressourcen Management (1)
- Ressourcenallokation (1)
- Rettungsroboter (1)
- Robot (1)
- Roboter (1)
- Rule-based Systems (1)
- Scheduling (1)
- Search-and-Rescue (1)
- Selbstkalibrierung (1)
- Self-calibration (1)
- Semantic Web (1)
- Semantics (1)
- Semantik (1)
- Sensor (1)
- Service Mobility (1)
- Sichtbarkeit (1)
- Similarity Measure (1)
- Simulator (1)
- Situationsbewusstsein (1)
- Skype (1)
- Small Satellites (1)
- Smart User Interaction (1)
- Social Web (1)
- Software (1)
- Software Engineering (1)
- Source Code Visualization (1)
- Soziale Software (1)
- Standortproblem (1)
- Statistics (1)
- Statistische Mechanik (1)
- Statistische Physik (1)
- Sternfreie Sprache (1)
- Steuerung (1)
- Stiffness (1)
- Stochastic Algorithms (1)
- Stochastik (1)
- Stochastikon (1)
- Stochastische Optimierung (1)
- Strahlentherapie (1)
- Straubing-Th´erien-Hierarchie (1)
- Straßennetzwerk (1)
- Straßenverkehr (1)
- Strukturelle Komplexität (1)
- Subgroup Mining (1)
- Subgruppenentdeckung (1)
- Substruktur (1)
- Suchverfahren (1)
- Synthetic Aperture Radar (1)
- System (1)
- Szenariogenerierung (1)
- Teaching (1)
- Telematik (1)
- Theoretical computer science (1)
- Thermografie (1)
- Tomografie (1)
- Topografie (1)
- Trainingssystem (1)
- Travelling-salesman-Problem (1)
- Tumor motion (1)
- Tumorbewegung (1)
- U-Bahnlinienplan (1)
- UI and Interaction Design (1)
- UML Klassendiagramm (1)
- UML class diagram (1)
- UMTS (1)
- URL (1)
- Underwater Mapping (1)
- Underwater Scanning (1)
- Unstetige Regelung (1)
- Usability (1)
- User Behavior (1)
- User Participation (1)
- Verbotenes Muster (1)
- Verbände (1)
- Verkehrslenkung (1)
- Verteilung von Inhalten (1)
- Video Quality Monitoring (1)
- Video Streaming (1)
- Videoübertragung (1)
- Virtuelles Netzwerk (1)
- Visibility (1)
- Visual Tracking (1)
- Visualisierung (1)
- Visualization (1)
- Voice-over-IP (VoIP) (1)
- Volltextsuche (1)
- Vorhersage (1)
- WLAN (1)
- Warteschlangentheorie (1)
- Werkstattdiagnose (1)
- Winkel (1)
- Wire relaxation (1)
- Wireless LAN (1)
- Wireless Sensor/Actuator Systems (1)
- Wissensbasiertes System (1)
- Wissenschaftliche Beobachtung (1)
- Wissensendeckung (1)
- Wissensrepräsentation (1)
- Worterweiterungen (1)
- Zeichnen von Graphen (1)
- Zeitdiskretes System (1)
- Zugangskontrolle (1)
- Zählprobleme (1)
- abgeschlossene Klassen (1)
- administrative boundary (1)
- admission control (1)
- aftermarket diagnostic (1)
- agile Prozesse (1)
- agile processes (1)
- angular schematization (1)
- approximation algorithms (1)
- automatic Layout (1)
- automatisches Layout (1)
- bit-parallel (1)
- boundary labeling (1)
- building (1)
- car-like robots (1)
- competitive location (1)
- complexity (1)
- computational complexity (1)
- computergestützte Softwaretechnik (1)
- concept search (1)
- constrained forest (1)
- contact representation (1)
- counting problems (1)
- crossing minimization (1)
- cryo-EM (1)
- cryo-ET (1)
- curves (1)
- d3web.Train (1)
- data structure (1)
- database (1)
- decission finding (1)
- deep learning (1)
- definite clause grammars (1)
- dial a ride (1)
- discrete-time analysis (1)
- driving simulation (1)
- dynamische Umgebungen (1)
- edge labeled graphs (1)
- educational tool (1)
- efficient algorithm (1)
- fast reroute (1)
- feature-matching (1)
- field-programmable architectures (1)
- field-programmable gate arrays (1)
- formation driving (1)
- full-text search (1)
- graph (1)
- graph decomposition (1)
- graphs (1)
- hardness (1)
- hybrid Diagnostic (1)
- hybride Diagnose (1)
- independent crossing (1)
- intelligente Applikationen (1)
- internet protocol (1)
- labeling (1)
- land-cover area (1)
- lattices (1)
- load balancing (1)
- logic programming (1)
- membrane protein (1)
- metro map (1)
- mission operation (1)
- mobile networks (1)
- model predictive control (1)
- model-base diagnosis (1)
- modeling techniques (1)
- monotone drawing (1)
- morphing (1)
- multi-vehicle formations (1)
- multi-vehicle rendezvous (1)
- mycoplasma (1)
- n-Gramm (1)
- n-gram (1)
- network (1)
- network design (1)
- network planning (1)
- network softwarization (1)
- network upgrade (1)
- networked robotics (1)
- networks (1)
- nonholonomic vehicles (1)
- optimization (1)
- overprovisioning (1)
- particle picking (1)
- partitions (1)
- performance evaluation (1)
- plan execution (1)
- pneumoniae (1)
- posets (1)
- q-Gramm (1)
- q-gram (1)
- radio resource management (1)
- receding horizon control (1)
- reload cost (1)
- remote control (1)
- resilience (1)
- right angle crossing (1)
- road network (1)
- robotics (1)
- routing (1)
- scenario creation (1)
- scheduling (1)
- semantic web (1)
- semantical aesthetic (1)
- semantische Ästhetik (1)
- sensor (1)
- simultaneous embedding (1)
- skalierbare Diagnose (1)
- slam (1)
- smooth orthogonal drawing (1)
- snow shoveling (1)
- spanning tree (1)
- stochastic thinking (1)
- stochastisches Denken (1)
- structural complexity (1)
- system (1)
- telematics (1)
- tomography (1)
- training systems (1)
- trajectory planning (1)
- tree (1)
- v (1)
- vernetzte Roboter (1)
- visual proteomics (1)
- vom Nutzer erfahrene Dienstgüte QoE (1)
- voting location (1)
- word clouds (1)
- word extensions (1)
- zooming (1)
- zukünftige Kommunikationsnetze (1)
- zukünftiges Internet (1)
- Ähnlichkeitsmaß (1)
Institute
Schriftenreihe
Sonstige beteiligte Institutionen
Historical maps are fascinating documents and a valuable source of information for scientists of various disciplines. Many of these maps are available as scanned bitmap images, but in order to make them searchable in useful ways, a structured representation of the contained information is desirable.
This book deals with the extraction of spatial information from historical maps. This cannot be expected to be solved fully automatically (since it involves difficult semantics), but is also too tedious to be done manually at scale.
The methodology used in this book combines the strengths of both computers and humans: it describes efficient algorithms to largely automate information extraction tasks and pairs these algorithms with smart user interactions to handle what is not understood by the algorithm. The effectiveness of this approach is shown for various kinds of spatial documents from the 16th to the early 20th century.
Small satellites contribute significantly in the rapidly evolving innovation in space engineering, in particular in distributed space systems for global Earth observation and communication services. Significant mass reduction by miniaturization, increased utilization of commercial high-tech components, and in particular standardization are the key drivers for modern miniature space technology.
This thesis addresses key fields in research and development on miniature satellite technology regarding efficiency, flexibility, and robustness. Here, these challenges are addressed by the University of Wuerzburg’s advanced pico-satellite bus, realizing a generic modular satellite architecture and standardized interfaces for all subsystems. The modular platform ensures reusability, scalability, and increased testability due to its flexible subsystem interface which allows efficient and compact integration of the entire satellite in a plug-and-play manner.
Beside systematic design for testability, a high degree of operational robustness is achieved by the consequent implementation of redundancy of crucial subsystems. This is combined with efficient fault detection, isolation and recovery mechanisms. Thus, the UWE-3 platform, and in particular the on-board data handling system and the electrical power system, offers one of the most efficient pico-satellite architectures launched in recent years and provides a solid basis for future extensions.
The in-orbit performance results of the pico-satellite UWE-3 are presented and summarize successful operations since its launch in 2013. Several software extensions and adaptations have been uploaded to UWE-3 increasing its capabilities. Thus, a very flexible platform for in-orbit software experiments and for evaluations of innovative concepts was provided and tested.
We use algebraic closures and structures which are derived from these in complexity theory. We classify problems with Boolean circuits and Boolean constraints according to their complexity. We transfer algebraic structures to structural complexity. We use the generation problem to classify important complexity classes.
Die Entwicklung eines wissensbasierten Systems, speziell eines Diagnosesystems, ist eine Teildisziplin der künstlichen Intelligenz und angewandten Informatik. Im Laufe der Forschung auf diesem Gebiet wurden verschiedene Lösungsansätze mit unterschiedlichem Erfolg bei der Anwendung in der Kraftfahrzeugdiagnose entwickelt. Diagnosesysteme in Vertragswerkstätten, das heißt in Fahrzeughersteller gebundenen Werkstätten, wenden hauptsächlich die fallbasierte Diagnostik an. Zum einen hält sich hier die Fahrzeugvielfalt in Grenzen und zum anderen besteht eine Meldepflicht bei neuen, nicht im System vorhandenen Fällen. Die freien Werkstätten verfügen nicht über eine solche Datenbank. Somit ist der fallbasierte Ansatz schwer umsetzbar. In freien Werkstätten - Fahrzeughersteller unabhängigen Werkstätten - basiert die Fehlersuche hauptsächlich auf Fehlerbäumen. Wegen der wachsenden Fahrzeugkomplexität, welche wesentlich durch die stark zunehmende Anzahl der durch mechatronische Systeme realisierten Funktionen bedingt ist, und der steigenden Typenvielfalt ist die geführte Fehlersuche in freien Werkstätten nicht immer zielführend. Um die Unterstützung des Personals von freien Werkstätten bei der zukünftigen Fehlersuche zu gewährleisten, werden neue Generationen von herstellerunabhängigen Diagnosetools benötigt, die die Probleme der Variantenvielfalt und Komplexität lösen. In der vorliegenden Arbeit wird ein Lösungsansatz vorgestellt, der einen qualitativen, modellbasierten Diagnoseansatz mit einem auf heuristischem Diagnosewissen basierenden Ansatz vereint. Neben der Grundlage zur Wissenserhebung werden in dieser Arbeit die theoretische Grundlage zur Beherrschung der Variantenvielfalt sowie die Tests für die erstellten Diagnosemodelle behandelt. Die Diagnose ist symptombasiert und die Inferenzmechanismen zur Verarbeitung des Diagnosewissens sind eine Kombination aus Propagierung der abweichenden physikalischen Größen im Modell und der Auswertung des heuristischen Wissens. Des Weiteren werden in dieser Arbeit verschiedene Aspekte der Realisierung der entwickelten theoretischen Grundlagen dargestellt, zum Beispiel: Systemarchitektur, Wissenserhebungsprozess, Ablauf des Diagnosevorgangs in den Werkstätten. Die Evaluierung der entwickelten Lösung bei der Wissenserhebung in Form von Modellerstellungen und Modellierungsworkshops sowie Feldtests dient nicht nur zur Bestätigung des entwickelten Ansatzes, sondern auch zur Ideenfindung für die Integration der entwickelten Tools in die existierende IT-Infrastruktur.
This work deals with teams in teleoperation scenarios, where one human team partner (supervisor) guides and controls multiple remote entities (either robotic or human) and coordinates their tasks. Such a team needs an appropriate infrastructure for sharing information and commands. The robots need to have a level of autonomy, which matches the assigned task. The humans in the team have to be provided with autonomous support, e.g. for information integration. Design and capabilities of the human-robot interfaces will strongly influence the performance of the team as well as the subjective feeling of the human team partners. Here, it is important to elaborate the information demand as well as how information is presented. Such human-robot systems need to allow the supervisor to gain an understanding of what is going on in the remote environment (situation awareness) by providing the necessary information. This includes achieving fast assessment of the robot´s or remote human´s state. Processing, integration and organization of data as well as suitable autonomous functions support decision making and task allocation and help to decrease the workload in this multi-entity teleoperation task. Interaction between humans and robots is improved by a common world model and a responsive system and robots. The remote human profits from a simplified user interface providing exactly the information needed for the actual task at hand. The topic of this thesis is the investigation of such teleoperation interfaces in human-robot teams, especially for high-risk, time-critical, and dangerous tasks. The aim is to provide a suitable human-robot team structure as well as analyze the demands on the user interfaces. On one side, it will be looked on the theoretical background (model, interactions, and information demand). On the other side, real implementations for system, robots, and user interfaces are presented and evaluated as testbeds for the claimed requirements. Rescue operations, more precisely fire-fighting, was chosen as an exemplary application scenario for this work. The challenges in such scenarios are high (highly dynamic environments, high risk, time criticality etc.) and it can be expected that results can be transferred to other applications, which have less strict requirements. The present work contributes to the introduction of human-robot teams in task-oriented scenarios, such as working in high risk domains, e.g. fire-fighting. It covers the theoretical background of the required system, the analysis of related human factors concepts, as well as discussions on implementation. An emphasis is placed on user interfaces, their design, requirements and user testing, as well as on the used techniques (three-dimensional sensor data representation, mixed reality, and user interface design guidelines). Further, the potential integration of 3D sensor data as well as the visualization on stereo visualization systems is introduced.
To jointly provide different services/technologies, like IP and Ethernet or IP and SDH/SONET, in a single network, equipment of multiple technologies needs to be deployed to the sites/Points of Presence (PoP) and interconnected with each other. Therein, a technology may provide transport functionality to other technologies and increase the number of available resources by using multiplexing techniques. By providing its own switching functionality, each technology creates connections in a logical layer which leads to the notion of multi-layer networks. The design of such networks comprises the deployment and interconnection of components to suit to given traffic demands. To prevent traffic loss due to failures of networking equipment, protection mechanisms need to be established. In multi-layer networks, protection usually can be applied in any of the considered layers. In turn, the hierarchical structure of multi-layer networks also bears shared risk groups (SRG). To achieve a cost-optimal resilient network, an appropriate combination of multiplexing techniques, technologies, and their interconnections needs to be found. Thus, network design is a combinatorial problem with a large parameter and solution space. After the design stage, the resources of a multi-layer network can be provided to traffic demands. Especially, dynamic capacity provisioning requires interaction of sites and layers, as well as accurate retrieval of constraint information. In recent years, generalized multiprotocol label switching (GMPLS) and path computation elements (PCE) have emerged as possible approaches for these challenges. Like the design, the provisioning of multi-layer networks comprises a variety of optimization parameters, like blocking probability, resilience, and energy efficiency. In this work, we introduce several efficient heuristics to approach the considered optimization problems. We perform capital expenditure (CAPEX)-aware design of multi-layer networks from scratch, based on IST NOBEL phase 2 project's cost and equipment data. We comprise traffic and resilience requirements in different and multiple layers as well as different network architectures. On top of the designed networks, we consider the dynamic provisioning of multi-layer traffic based on the GMPLS and PCE architecture. We evaluate different PCE deployments, information retrieval strategies, and re-optimization. Finally, we show how information about provisioning utilization can be used to provide a feedback for network design.
In the last years, visual methods have been introduced in industrial software production and teaching of software engineering. In particular, the international standardization of a graphical software engineering language, the Unified Modeling Language (UML) was a reason for this tendency. Unfortunately, various problems exist in concrete realizations of tools, e.g. due to a missing compliance to the standard. One problem is the automatic layout, which is required for a consistent automatic software design. The thesis derives reasons and criteria for an automatic layout method, which produces drawings of UML class diagrams according to the UML specification and issues of human computer interaction, e.g. readability. A unique set of aesthetic criteria is combined from four different disciplines involved in this topic. Based on these aethetic rules, a hierarchical layout algorithm is developed, analyzed, measured by specialized measuring techniques and compared to related work. Then, the realization of the algorithm as a Java framework is given as an architectural description. Finally, adaptions to anticipated future changes of the UML, improvements of the framework and example drawings of the implementation are given.
In der vorliegenden Arbeit wird das Problem der Kalibrierung Agenten-basierter Simulationen (ABS) behandelt, also das Problem, die Parameterwerte eines Agenten-basierten Simulationsmodells so einzustellen, dass valides Simulationsverhalten erreicht wird. Das Kalibrierungsproblem für Simulationen an sich ist nicht neu und ist im Rahmen klassischer Simulationsparadigmen, wie z.B. der Makro-Simulation, fester Bestandteil der Forschung. Im Vergleich zu den dort betrachteten Kalibrierungsproblemen zeichnet sich das Kalibrierungsproblem für ABS jedoch durch eine Reihe zusätzlicher Herausforderungen aus, welche die direkte Anwendung existierender Kalibrierungsverfahren in begrenzter Zeit erschweren, bzw. nicht mehr sinnvoll zulassen. Die Lösung dieser Probleme steht im Zentrum dieser Dissertation: Das Ziel besteht darin, den Nutzer bei der Kalibrierung von ABS auf der Basis von unzureichenden, potentiell fehlerhaften Daten und Wissen zu unterstützen. Dabei sollen drei Hauptprobleme gelöst werden: 1)Vereinfachung der Kalibrierung großer Agenten-Parametermengen auf der Mikro- Ebene in Agenten-basierten Simulationen durch Ausnutzung der spezifischen Struktur von ABS (nämlich dem Aufbau aus einer Menge von Agentenmodellen). 2)Kalibrierung Agenten-basierter Simulationen, so dass auf allen relevanten Beobachtungsebenen valides Simulationsverhalten erzeugt wird (mindestens Mikro und Makro-Ebene). Als erschwerende Randbedingung muss die Kalibrierung unter der Voraussetzung einer Makro-Mikro-Wissenslücke durchgeführt werden. 3)Kalibrierung Agenten-basierter Simulationen auf der Mikro-Ebene unter der Voraussetzung, dass zur Kalibrierung einzelner Agentenmodelle nicht ausreichend und potentiell verfälschte Daten zur Verhaltensvalidierung zur Verfügung stehen. Hierzu wird in dieser Arbeit das sogenannte Makro-Mikro-Verfahren zur Kalibrierung von Agenten-basierten Simulationen entwickelt. Das Verfahren besteht aus einem Basisverfahren, das im Verlauf der Arbeit um verschiedene Zusatzverfahren erweitert wird. Das Makro-Mikro-Verfahren und seine Erweiterungen sollen dazu dienen, die Modellkalibrierung trotz stark verrauschter Daten und eingeschränktem Wissen über die Wirkungszusammenhänge im Originalsystem geeignet zu ermöglichen und dabei den Kalibrierungsprozess zu beschleunigen: 1) Makro-Mikro-Kalibrierungsverfahren: Das in dieser Arbeit entwickelte Makro- Mikro-Verfahren unterstützt den Nutzer durch eine kombinierte Kalibrierung auf der Mikro- und der Makro-Beobachtungsebene, die gegebenenfalls durch Zwischenebenen erweitert werden kann. Der Grundgedanke des Verfahrens besteht darin, das Kalibrierungsproblem in eines auf aggregierter Verhaltensebene und eines auf der Ebene des Mikro-Agentenverhaltens aufzuteilen. Auf der Makro-Ebene wird nach validen idealen aggregierten Verhaltensmodellen (IVM) der Agenten gesucht. Auf der Mikro-Ebene wird versucht die individuellen Modelle der Agenten auf Basis des erwünschten Gesamtverhaltens und der ermittelten IVM so zu kalibrieren, das insgesamt Simulationsverhalten entsteht, das sowohl auf Mikro- als auch auf Makro-Ebene valide ist. 2) Erweiterung 1: Robuste Kalibrierung: Um den Umgang mit potentiell verrauschten Validierungskriterien (d.h. mit verrauschten Daten über ein Originalsystem, auf denen die Validierungskriterien der Simulation beruhen) und Modellteilen während der Kalibrierung von ABS zu ermöglichen, wird eine robuste Kalibrierungstechnik zur Anwendung im Makro-Mikro-Verfahren entwickelt. 3) Erweiterung 2: Kalibrierung mit Heterogenitätssuche: Als zweite Erweiterung des Makro-Mikro-Verfahrens wird ein Verfahren entwickelt, das das Problem des unklaren Detaillierungsgrades von ABS auf der Ebene der Parameterwerte adressiert. Prinzipiell kann zwar jeder Agent unterschiedliche Parameterwerte verwenden, obwohl eine geringere Heterogenität zur Erzeugung validen Verhaltens ausreichend wäre. Die entwickelte Erweiterung versucht, während der Kalibrierung, eine geeignete Heterogenitätsausprägung für die Parameterwerte der Agenten zu ermitteln. Unter einer Heterogenitätsausprägung wird dabei eine Einteilung der simulierten Agenten in Gruppen mit jeweils gleichen Parameterwerten verstanden. Die Heterogenitätssuche dient dazu, einen Kompromiss zu finden zwischen der Notwendigkeit, sehr große Parametersuchräume durchsuchen zu müssen und gleichzeitig den Suchraum so klein wie möglich halten zu wollen.
In many cases, problems, data, or information can be modeled as graphs. Graphs can be used as a tool for modeling in any case where connections between distinguishable objects occur. Any graph consists of a set of objects, called vertices, and a set of connections, called edges, such that any edge connects a pair of vertices. For example, a social network can be modeled by a graph by
transforming the users of the network into vertices and friendship relations between users into edges. Also physical networks like computer networks or transportation networks, for example, the metro network of a city, can be seen as graphs.
For making graphs and, thereby, the data that is modeled, well-understandable for users, we need a visualization. Graph drawing deals with algorithms for visualizing graphs. In this thesis, especially the use of crossings and curves is investigated for graph drawing problems under additional constraints. The constraints that occur in the problems investigated in this thesis especially restrict the positions of (a part of) the vertices; this is done either as a hard constraint or as an optimization criterion.
Given points in the plane, connect them using minimum ink. Though the task seems simple, it turns out to be very time consuming. In fact, scientists believe that computers cannot efficiently solve it. So, do we have to resign? This book examines such NP-hard network-design problems, from connectivity problems in graphs to polygonal drawing problems on the plane. First, we observe why it is so hard to optimally solve these problems. Then, we go over to attack them anyway. We develop fast algorithms that find approximate solutions that are very close to the optimal ones. Hence, connecting points with slightly more ink is not hard.
Knowledge-based systems (KBS) face an ever-increasing interest in various disciplines and contexts. Yet, the former aim to construct the ’perfect intelligent software’ continuously shifts to user-centered, participative solutions. Such systems enable users to contribute their personal knowledge to the problem solving process for increased efficiency and an ameliorated user experience. More precisely, we define non-functional key requirements of participative KBS as: Transparency (encompassing KBS status mediation), configurability (user adaptability, degree of user control/exploration), quality of the KB and UI, and evolvability (enabling the KBS to grow mature with their users). Many of those requirements depend on the respective target users, thus calling for a more user-centered development. Often, also highly expertise domains are targeted — inducing highly complex KBs — which requires a more careful and considerate UI/interaction design. Still, current KBS engineering (KBSE) approaches mostly focus on knowledge acquisition (KA) This often leads to non-optimal, little reusable, and non/little evaluated KBS front-end solutions.
In this thesis we propose a more encompassing KBSE approach. Due to the strong mutual influences between KB and UI, we suggest a novel form of intertwined UI and KB development. We base the approach on three core components for encompassing KBSE:
(1) Extensible prototyping, a tailored form of evolutionary prototyping; this builds on mature UI prototypes and offers two extension steps for the anytime creation of core KBS prototypes (KB + core UI) and fully productive KBS (core KBS prototype + common framing functionality). (2) KBS UI patterns, that define reusable solutions for the core KBS UI/interaction; we provide a basic collection of such patterns in this work. (3) Suitable usability instruments for the assessment of the KBS artifacts. Therewith, we do not strive for ’yet another’ self-contained KBS engineering methodology. Rather, we motivate to extend existing approaches by the proposed key components. We demonstrate this based on an agile KBSE model.
For practical support, we introduce the tailored KBSE tool ProKEt. ProKEt offers a basic selection of KBS core UI patterns and corresponding configuration options out of the box; their further adaption/extension is possible on various levels of expertise. For practical usability support, ProKEt offers facilities for quantitative and qualitative data collection. ProKEt explicitly fosters the suggested, intertwined development of UI and KB. For seamlessly integrating KA activities, it provides extension points for two selected external KA tools: For KnowOF, a standard office based KA environment. And for KnowWE, a semantic wiki for collaborative KA. Therewith, ProKEt offers powerful support for encompassing, user-centered KBSE.
Finally, based on the approach and the tool, we also developed a novel KBS type: Clarification KBS as a mashup of consultation and justification KBS modules. Those denote a specifically suitable realization for participative KBS in highly expertise contexts and consequently require a specific design. In this thesis, apart from more common UI solutions, we particularly also introduce KBS UI patterns especially tailored towards Clarification KBS.
In this doctoral thesis we cover the performance evaluation of next generation data plane architectures, comprised of complex software as well as programmable hardware components that allow fine granular configuration. In the scope of the thesis we propose mechanisms to monitor the performance of singular components and model key performance indicators of software based packet processing solutions. We present novel approaches towards network abstraction that allow the integration of heterogeneous data plane technologies into a singular network while maintaining total transparency between control and data plane. Finally, we investigate a full, complex system consisting of multiple software-based solutions and perform a detailed performance analysis. We employ simulative approaches to investigate overload control mechanisms that allow efficient operation under adversary conditions. The contributions of this work build the foundation for future research in the areas of network softwarization and network function virtualization.
Starfree regular languages can be build up from alphabet letters by using only Boolean operations and concatenation. The complexity of these languages can be measured with the so-called dot-depth. This measure leads to concatenation hierarchies like the dot-depth hierarchy (DDH) and the closely related Straubing-Thérien hierarchy (STH). The question whether the single levels of these hierarchies are decidable is still open and is known as the dot-depth problem. In this thesis we prove/reprove the decidability of some lower levels of both hierarchies. More precisely, we characterize these levels in terms of patterns in finite automata (subgraphs in the transition graph) that are not allowed. Therefore, such characterizations are called forbidden-pattern characterizations. The main results of the thesis are as follows: forbidden-pattern characterization for level 3/2 of the DDH (this implies the decidability of this level) decidability of the Boolean hierarchy over level 1/2 of the DDH definition of decidable hierarchies having close relations to the DDH and STH Moreover, we prove/reprove the decidability of the levels 1/2 and 3/2 of both hierarchies in terms of forbidden-pattern characterizations. We show the decidability of the Boolean hierarchies over level 1/2 of the DDH and over level 1/2 of the STH. A technique which uses word extensions plays the central role in the proofs of these results. With this technique it is possible to treat the levels 1/2 and 3/2 of both hierarchies in a uniform way. Furthermore, it can be used to prove the decidability of the mentioned Boolean hierarchies. Among other things we provide a combinatorial tool that allows to partition words of arbitrary length into factors of bounded length such that every second factor u leads to a loop with label u in a given finite automaton.
At the center of the Internet’s protocol stack stands the Internet Protocol (IP) as a common denominator that enables all communication. To make routing efficient, resilient, and scalable, several aspects must be considered. Care must be taken that traffic is well balanced to make efficient use of the existing network resources, both in failure free operation and in failure scenarios.
Finding the optimal routing in a network is an NP-complete problem. Therefore, routing optimization is usually performed using heuristics. This dissertation shows that a routing optimized with one objective function is often not good when looking at other objective functions. It can even be worse than unoptimized routing with respect to that objective function. After looking at failure-free routing and traffic distribution in different failure scenarios, the analysis is extended to include the loop-free alternate (LFA) IP fast reroute mechanism. Different application scenarios of LFAs are examined and a special focus is set on the fact that LFAs usually cannot protect all traffic in a network even against single link failures. Thus, the routing optimization for LFAs is targeted on both link utilization and failure coverage. Finally, the pre-congestion notification mechanism PCN for network admission control and overload protection is analyzed and optimized. Different design options for implementing the protocol are compared, before algorithms are developed for the calculation and optimization of protocol parameters and PCN-based routing.
The second part of the thesis tackles a routing problem that can only be resolved on a global scale. The scalability of the Internet is at risk since a major and intensifying growth of the interdomain routing tables has been observed. Several protocols and architectures are analyzed that can be used to make interdomain routing more scalable. The most promising approach is the locator/identifier (Loc/ID) split architecture which separates routing from host identification. This way, changes in connectivity, mobility of end hosts, or traffic-engineering activities are hidden from the routing in the core of the Internet and the routing tables can be kept much smaller. All of the currently proposed Loc/ID split approaches have their downsides. In particular, the fact that most architectures use the ID for routing outside the Internet’s core is a poor design, which inhibits many of the possible features of a new routing architecture. To better understand the problems and to provide a solution for a scalable routing design that implements a true Loc/ID split, the new GLI-Split protocol is developed in this thesis, which provides separation of global and local routing and uses an ID that is independent from any routing decisions.
Besides GLI-Split, several other new routing architectures implementing Loc/ID split have been proposed for the Internet. Most of them assume that a mapping system is queried for EID-to-RLOC mappings by an intermediate node at the border of an edge network. When the mapping system is queried by an intermediate node, packets are already on their way towards their destination, and therefore, the mapping system must be fast, scalable, secure, resilient, and should be able to relay packets without locators to nodes that can forward them to the correct destination. The dissertation develops a classification for all proposed mapping system architectures and shows their similarities and differences. Finally, the fast two-level mapping system FIRMS is developed. It includes security and resilience features as well as a relay service for initial packets of a flow when intermediate nodes encounter a cache miss for the EID-to-RLOC mapping.
Wireless communication is nothing new. The first data transmissions based on electromagnetic waves have been successfully performed at the end of the 19th century. However, it took almost another century until the technology was ripe for mass market. The first mobile communication systems based on the transmission of digital data were introduced in the late 1980s. Within just a couple of years they have caused a revolution in the way people communicate. The number of cellular phones started to outnumber the fixed telephone lines in many countries and is still rising. New technologies in 3G systems, such as UMTS, allow higher data rates and support various kinds of multimedia services. Nevertheless, the end of the road in wireless communication is far from being reached. In the near future, the Internet and cellular phone systems are expected to be integrated to a new form of wireless system. Bandwidth requirements for a rich set of wireless services, e.g.\ video telephony, video streaming, online gaming, will be easily met. The transmission of voice data will just be another IP based service. On the other hand, building such a system is by far not an easy task. The problems in the development of the UMTS system showed the high complexity of wireless systems with support for bandwidth-hungry, IP-based services. But the technological challenges are just one difficulty. Telecommunication systems are planned on a world-wide basis, such that standard bodies, governments, institutions, hardware vendors, and service providers have to find agreements and compromises on a number of different topics. In this work, we provide the reader with a discussion of many of the topics involved in the planning of a Wireless LAN system that is capable of being integrated into the 4th generation mobile networks (4G) that is being discussed nowadays. Therefore, it has to be able to cope with interactive voice and video traffic while still offering high data rates for best effort traffic. Let us assume a scenario where a huge office complex is completely covered with Wireless LAN access points. Different antenna systems are applied in order to reduce the number of access points that are needed on the one hand, while optimizing the coverage on the other. No additional infrastructure is implemented. Our goal is to evaluate whether the Wireless LAN technology is capable of dealing with the various demands of such a scenario. First, each single access point has to be capable of supporting best-effort and Quality of Service (QoS) demanding applications simultaneously. The IT infrastructure in our scenario consists solely of Wireless LAN, such that it has to allow users surfing the Web, while others are involved in voice calls or video conferences. Then, there is the problem of overlapping cells. Users attached to one access point produce interference for others. However, the QoS support has to be maintained, which is not an easy task. Finally, there are nomadic users, which roam from one Wireless LAN cell to another even during a voice call. There are mechanisms in the standard that allow for mobility, but their capabilities for QoS support are yet to be studied. This shows the large number of unresolved issues when it comes to Wireless LAN in the context of 4G networks. In this work we want to tackle some of the problems.
While developing modern applications, it is necessary to ensure an efficient and performant communication between different applications. In current environments, a middleware software is used, which supports the publish/subscribe communication pattern. Using this communication pattern, a publisher sends information encapsulated in messages to the middleware. A subscriber registers its interests at the middleware. The monograph describes three different steps to determine the performance of such a system. In a first step, the message throughput performance of a publish/subscribe in different scenarios is measured using a Java Message Service (JMS) based implementation. In the second step the maximum achievable message throughput is described by adapted models depending on the filter complexity and the replication grade. Using the model, the performance characteristics of a specific system in a given scenario can be determined. These numbers are used for the queuing model described in the third part of the thesis, which supports the dimensioning of a system in realistic scenarios. Additionally, we introduce a method to approximate an M/G/1 system numerically in an efficient way, which can be used for real time analysis to predict the expected performance in a certain scenario. Finally, the analytical model is used to investigate different possibilities to ensure the scalability of the maximum achievable message throughput of the overall system.
Verteilte dynamische Systeme unter lokalen und globalen Gesichtspunkten zu optimieren ist eine schwierige Aufgabe. Zwar sind grundsätzliche Auswirkungen einzelner Maßnahmen häufig bekannt, durch widerstrebende Ziele, Wechselwirkungen zwischen Prozessen und Nebenwirkungen von Maßnahmen ist ein analytisches Vorgehen bei der Optimierung nicht möglich. Besonders schwierig wird es, wenn lokale Einheiten einerseits ihre Ziele und Autonomie behalten sollen, aber durch zentrale Vorgaben bzw. Anreize so gesteuert werden sollen, dass ein übergeordnetes Ziel erreicht wird. Ein praktisches Beispiel dieses allgemeinen Optimierungsproblems findet sich im Gesundheitswesen. Das Management von modernen Kliniken ist stets mit dem Problem konfrontiert, die Qualität der Pflege zu gewährleisten und gleichzeitig kosteneffizient zu arbeiten. Hier gilt es unter gegeben Rahmenbedingungen und bei Respektierung der Autonomie der Funktionseinheiten, Optimierungsmaßnahmen zu finden und durchzuführen. Vorhandene Werkzeuge zur Simulation und Modellierung bieten für diese Aufgabe keine ausreichend guten Vorgehensmodelle und Modellierungsmechanismen. Die agentenbasierte Simulation ermöglicht die Abbildung solcher Systeme und die Durchführung von Simulationsexperimenten zur Bewertung einzelner Maßnahmen. Es werden Lösungswege und Werkzeuge vorgestellt und evaluiert, die den Benutzer bei der Formalisierung des Wissens und der Modellierung solch komplexer Szenarien unterstützen und ein systematisches Vorgehen zur Optimierung ermöglichen.
Radiation therapy today, on account of improvements in treatment procedures over the last 60 years, allows precise treatment of static tumors inside the human body. However, irradiation of moving tumors is still a challenging task as moving tumors often leave the treatment beam and the radiation dose delivered to the tumor reduces simultaneously increasing that on healthy tissue. This research work aims to push the frontiers of radiation therapy in order to enable precise treatment of moving tumors with focus on research and development of a unique real-time system enabling active motion compensation through robotic means to compensate tumor motion. During treatment, patients lie on a treatment couch which is normally used for static position corrections of patient set-up errors prior to radiation treatment. The treatment couch used, called HexaPOD, is a parallel manipulator with six degrees of freedom which can precisely position heavy loads inside a small region. Despite the HexaPOD not initially built with dynamics in mind, it is used in this work for sustained motion compensation by moving patients such that tumors stay precisely located at the center of the treatment beam during the complete course of treatment. In order to realize real-time tumor motion compensation by means of the HexaPOD, several challanges need to be addressed. Real-time aspects are covered by the adoption of a hard real-time operation system in combination with measurement and estimation of latencies of all physical quantities in the compensation system such as tumor or breathing position measurements. Accurate timing information is respected consistently in the whole system and all software-induced latencies are adaptively compensated for. This requires knowledge of future tumor positions from predictors. Several predictors for breathing and tumor motion predictions are proposed and evaluated in terms of a variety of different performance metrics. Extensions to prediction algorithms are introduced fusing both breathing and tumor position information to allow for predictions without the need of an explicit correlation model. Predictions determine the future motion path of the HexaPOD in order to compensate for tumor motion. Several control schemes are developed to enable reference tracking for the HexaPOD. Based on linear and non-linear dynamic modelling of the HexaPOD with system identification methods, a first controller is derived in the form of a model predictive controller. A second controller is proposed based on an assumption of the working principle of the HexaPOD's internal controller. Finally, a third controller is derived as combination of the first and second one. For each of these controllers, comparative results with real hardware experiments and humans in the loop as well as choices of free parameters are presented and discussed. Apart from precise tracking, emphasis is placed on patient comfort which is of crucial importance for acceptance of the system. It is demonstrated that smooth trajectories can be realized by the controllers to guarantee that patients feel comfortable while their tumor motion is compensated at sub-millimeter accuracies. Overall errors of the system are analyzed by relating them to tracking and prediction errors. By exploiting the properties of different predictors, it is shown that the startup time until tracking is reached can be reduced to only a few seconds, even in the case of an initially at-rest HexaPOD and with no initial knowledge of tumor motion. This makes the system especially suitable for the relatively short-fractionated treatment sessions for lung tumors. The tumor motion compensation system has been developed solely based on standard clinical hardware, found in most treatment rooms. With a simple and flexible design, existing treatment can be updated in a cost-efficient way to introduce motion compensation capabilities. Simultaneously, the system does not impose any constraints on state-of-the-art treatment types such as intensity modulated radiotherapy or volumetric modulated arc therapy. Supporting different compensation modes, the system can be applied to any moving tumor whether its motion is predictable (lung tumors) or unpredictable (prostate tumors). By integration of adequate tumor position determination methods, the system can be easily extended to other tumors as well.
This work focuses on coordination methods and the control of motion in groups of nonholonomic wheeled mobile robots, in particular of the car-like type. These kind of vehicles are particularly restricted in their mobility. In the main part of this work the two problems of formation motion coordination and of rendezvous in distributed multi-vehicle systems are considered. We introduce several enhancements to an existing motion planning approach for formations of nonholonomic mobile robots. Compared to the original method, the extended approach is able to handle time-varying reference speeds as well as adjustments of the formation's shape during reference trajectory segments with continuously differentiable curvature. Additionally, undesired discontinuities in the speed and steering profiles of the vehicles are avoided. Further, the scenario of snow shoveling on an airfield by utilizing multiple formations of autonomous snowplows is discussed. We propose solutions to the subproblems of motion planning for the formations and tracking control for the individual vehicles. While all situations that might occur have been tested in a simulation environment, we also verified the developed tracking controller in real robot hardware experiments. The task of the rendezvous problem in groups of car-like robots is to drive all vehicles to a common position by means of decentralized control laws. Typically there exists no direct interaction link between all of the vehicles. In this work we present decentralized rendezvous control laws for vehicles with free and with bounded steering. The convergence properties of the approaches are analyzed by utilizing Lyapunov based techniques. Furthermore, they are evaluated within various simulation experiments, while the bounded steering case is also verified within laboratory hardware experiments. Finally we introduce a modification to the bounded steering system that increases the convergence speed at the expense of a higher traveled distance of the vehicles.
Routing is one of the most important issues in any communication network. It defines on which path packets are transmitted from the source of a connection to the destination. It allows to control the distribution of flows between different locations in the network and thereby is a means to influence the load distribution or to reach certain constraints imposed by particular applications. As failures in communication networks appear regularly and cannot be completely avoided, routing is required to be resilient against such outages, i.e., routing still has to be able to forward packets on backup paths even if primary paths are not working any more.
Throughout the years, various routing technologies have been introduced that are very different in their control structure, in their way of working, and in their ability to handle certain failure cases. Each of the different routing approaches opens up their own specific questions regarding configuration, optimization, and inclusion of resilience issues. This monograph investigates, with the example of three particular routing technologies, some concrete issues regarding the analysis and optimization of resilience. It thereby contributes to a better general, technology-independent understanding of these approaches and of their diverse potential for the use in future network architectures.
The first considered routing type, is decentralized intra-domain routing based on administrative IP link costs and the shortest path principle. Typical examples are common today's intra-domain routing protocols OSPF and IS-IS. This type of routing includes automatic restoration abilities in case of failures what makes it in general very robust even in the case of severe network outages including several failed components. Furthermore, special IP-Fast Reroute mechanisms allow for a faster reaction on outages. For routing based on link costs, traffic engineering, e.g. the optimization of the maximum relative link load in the network, can be done indirectly by changing the administrative link costs to adequate values.
The second considered routing type, MPLS-based routing, is based on the a priori configuration of primary and backup paths, so-called Label Switched Paths. The routing layout of MPLS paths offers more freedom compared to IP-based routing as it is not restricted by any shortest path constraints but any paths can be setup. However, this in general involves a higher configuration effort.
Finally, in the third considered routing type, typically centralized routing using a Software Defined Networking (SDN) architecture, simple switches only forward packets according to routing decisions made by centralized controller units. SDN-based routing layouts offer the same freedom as for explicit paths configured using MPLS. In case of a failure, new rules can be setup by the controllers to continue the routing in the reduced topology. However, new resilience issues arise caused by the centralized architecture. If controllers are not reachable anymore, the forwarding rules in the single nodes cannot be adapted anymore. This might render a rerouting in case of connection problems in severe failure scenarios infeasible.