004 Datenverarbeitung; Informatik
Refine
Has Fulltext
- yes (68)
Is part of the Bibliography
- yes (68)
Year of publication
Document Type
- Doctoral Thesis (68) (remove)
Language
- English (68) (remove)
Keywords
- Leistungsbewertung (13)
- Robotik (8)
- Mobiler Roboter (6)
- Autonomer Roboter (5)
- Komplexitätstheorie (5)
- Netzwerk (5)
- Optimierung (5)
- Theoretische Informatik (5)
- Overlay-Netz (4)
- Routing (4)
- Verteiltes System (4)
- Algorithmus (3)
- Approximationsalgorithmus (3)
- Computer Vision (3)
- Dienstgüte (3)
- Drahtloses Sensorsystem (3)
- Graph (3)
- Graphenzeichnen (3)
- Komplexität (3)
- Machine Learning (3)
- Maschinelles Lernen (3)
- Mensch-Maschine-Schnittstelle (3)
- Netzwerkmanagement (3)
- Optimization (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)
- Lokalisation (2)
- Maschinelles Sehen (2)
- Mensch-Maschine-System (2)
- Mensch-Roboter-Interaktion (2)
- Mixed Reality (2)
- Modellierung (2)
- PROLOG <Programmiersprache> (2)
- Punktwolke (2)
- QoE (2)
- Quality of Experience (2)
- Rechnernetz (2)
- Resilience (2)
- Resource Management (2)
- Ressourcenmanagement (2)
- Robotics (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)
- 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)
- Admission Control (1)
- Approximation (1)
- Arctic (1)
- Arterie (1)
- Artery (1)
- Automat <Automatentheorie> (1)
- Automata Theory (1)
- Automatentheorie (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)
- Betriebssystem (1)
- Bewegungskompensation (1)
- Bewegungskoordination (1)
- Bildverarbeitung (1)
- Biological Networks (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)
- 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)
- Computersimulation (1)
- Computerunterstütztes Lernen (1)
- Content Distribution (1)
- DHT (1)
- Deep Georeferencing (1)
- Deep Learning (1)
- Deep learning (1)
- Dependency Graph (1)
- Design (1)
- Dezentrale Regelung (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 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)
- Erfüllbarkeitsproblem (1)
- Erweiterte Realität (1)
- Euclidean plane (1)
- Euklidische Ebene (1)
- Expert System (1)
- Expertensystem (1)
- Fairness (1)
- Feature Based Registration (1)
- Fehlertoleranz (1)
- Fernsteuerung (1)
- Formale Sprache (1)
- Formation (1)
- Formationsbewegung (1)
- Formmessung (1)
- Funkressourcenverwaltung (1)
- Gastroenterologische Endoskopie (1)
- Gefühl (1)
- Generalisierung <Kartografie> (1)
- Generation Problem (1)
- Generierungsproblem (1)
- Genetic Optimization (1)
- Genetische Optimierung (1)
- Georeferenzierung (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)
- Hintergrundwissen (1)
- Historical Maps (1)
- Historische Karte (1)
- Historische Landkarten (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)
- Information Extraction (1)
- Interaktion (1)
- Internet Protokoll (1)
- Isomorphie (1)
- Itinerare (1)
- Itineraries (1)
- Java <Programmiersprache> (1)
- Java Message Service (1)
- Kademlia (1)
- Kanalzugriff (1)
- Karte (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)
- Kooperierende mobile Roboter (1)
- Kreuzungsminimierung (1)
- Kryoelektronenmikroskopie (1)
- Kurve (1)
- Land Cover Classification (1)
- Landkartenbeschriftung (1)
- Landnutzungskartierung (1)
- Laser scanning (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)
- 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)
- Mobiles Internet (1)
- Mobilfunk (1)
- Modellierungstechniken (1)
- Modularität (1)
- Multi-Layer (1)
- Multi-Network Service (1)
- Multi-Netzwerk Dienste (1)
- Multi-Paradigm Programming (1)
- Multi-Paradigm Programming Framework (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)
- 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)
- Planung (1)
- PolSAR (1)
- Polyeder (1)
- Polypektomie (1)
- Post's Classes (1)
- Postsche Klassen (1)
- Prediction (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)
- Regelung (1)
- Registration (1)
- Registrierung (1)
- Registrierung <Bildverarbeitung> (1)
- Reguläre Sprache (1)
- Relief <Geografie> (1)
- Rendezvous (1)
- Ressourcen Management (1)
- Ressourcenallokation (1)
- Rettungsroboter (1)
- Satellit (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)
- Simulation (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)
- Stochastische Optimierung (1)
- Strahlentherapie (1)
- Straubing-Th´erien-Hierarchie (1)
- Strukturelle Komplexität (1)
- Subgroup Mining (1)
- Subgruppenentdeckung (1)
- Substruktur (1)
- Synthetic Aperture Radar (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)
- Vorhersage (1)
- WLAN (1)
- Warteschlangentheorie (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)
- agile Prozesse (1)
- agile processes (1)
- angular schematization (1)
- approximation algorithms (1)
- automatic Layout (1)
- automatisches Layout (1)
- boundary labeling (1)
- building (1)
- car-like robots (1)
- competitive location (1)
- complexity (1)
- computational complexity (1)
- computergestützte Softwaretechnik (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)
- deep learning (1)
- definite clause grammars (1)
- dial a ride (1)
- discrete-time analysis (1)
- edge labeled graphs (1)
- educational tool (1)
- efficient algorithm (1)
- fast reroute (1)
- formation driving (1)
- graph (1)
- graph decomposition (1)
- graphs (1)
- hardness (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)
- mobile networks (1)
- mobile robots (1)
- model predictive control (1)
- modeling techniques (1)
- monotone drawing (1)
- morphing (1)
- multi-vehicle formations (1)
- multi-vehicle rendezvous (1)
- mycoplasma (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)
- pneumoniae (1)
- posets (1)
- radio resource management (1)
- receding horizon control (1)
- reload cost (1)
- remote control (1)
- resilience (1)
- right angle crossing (1)
- robotics (1)
- routing (1)
- semantic web (1)
- semantical aesthetic (1)
- semantische Ästhetik (1)
- sensor (1)
- simultaneous embedding (1)
- smooth orthogonal drawing (1)
- snow shoveling (1)
- spanning tree (1)
- structural complexity (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
For formative evaluations of user experience (UX) a variety of methods have been developed over the years. However, most techniques require the users to interact with the study as a secondary task. This active involvement in the evaluation is not inclusive of all users and potentially biases the experience currently being studied. Yet there is a lack of methods for situations in which the user has no spare cognitive resources. This condition occurs when 1) users' cognitive abilities are impaired (e.g., people with dementia) or 2) users are confronted with very demanding tasks (e.g., air traffic controllers). In this work we focus on emotions as a key component of UX and propose the new structured observation method Proxemo for formative UX evaluations. Proxemo allows qualified observers to document users' emotions by proxy in real time and then directly link them to triggers. Technically this is achieved by synchronising the timestamps of emotions documented by observers with a video recording of the interaction.
In order to facilitate the documentation of observed emotions in highly diverse contexts we conceptualise and implement two separate versions of a documentation aid named Proxemo App. For formative UX evaluations of technology-supported reminiscence sessions with people with dementia, we create a smartwatch app to discreetly document emotions from the categories anger, general alertness, pleasure, wistfulness and pride. For formative UX evaluations of prototypical user interfaces with air traffic controllers we create a smartphone app to efficiently document emotions from the categories anger, boredom, surprise, stress and pride. Descriptive case studies in both application domains indicate the feasibility and utility of the method Proxemo and the appropriateness of the respectively adapted design of the Proxemo App.
The third part of this work is a series of meta-evaluation studies to determine quality criteria of Proxemo. We evaluate Proxemo regarding its reliability, validity, thoroughness and effectiveness, and compare Proxemo's efficiency and the observers' experience to documentation with pen and paper. Proxemo is reliable, as well as more efficient, thorough and effective than handwritten notes and provides a better UX to observers. Proxemo compares well with existing methods where benchmarks are available.
With Proxemo we contribute a validated structured observation method that has shown to meet requirements formative UX evaluations in the extreme contexts of users with cognitive impairments or high task demands. Proxemo is agnostic regarding researchers' theoretical approaches and unites reductionist and holistic perspectives within one method.
Future work should explore the applicability of Proxemo for further domains and extend the list of audited quality criteria to include, for instance, downstream utility. With respect to basic research we strive to better understand the sources leading observers to empathic judgments and propose reminisce and older adults as model environment for investigating mixed emotions.
Currently, we observe a strong growth of services and applications, which use the Internet for data transport. However, the network requirements of these applications differ significantly. This makes network management difficult, since it complicated to separate network flows into application classes without inspecting application layer data. Network virtualization is a promising solution to this problem. It enables running different virtual network on the same physical substrate. Separating networks based on the service supported within allows controlling each network according to the specific needs of the application. The aim of such a network control is to optimize the user perceived quality as well as the cost efficiency of the data transport. Furthermore, network virtualization abstracts the network functionality from the underlying implementation and facilitates the split of the currently tightly integrated roles of Internet Service Provider and network owner. Additionally, network virtualization guarantees that different virtual networks run on the same physical substrate do not interfere with each other. This thesis discusses different aspects of the network virtualization topic. It is focused on how to manage and control a virtual network to guarantee the best Quality of Experience for the user. Therefore, a top-down approach is chosen. Starting with use cases of virtual networks, a possible architecture is derived and current implementation options based on hardware virtualization are explored. In the following, this thesis focuses on assessing the Quality of Experience perceived by the user and how it can be optimized on application layer. Furthermore, options for measuring and monitoring significant network parameters of virtual networks are considered.
The Internet sees an ongoing transformation process from a single best-effort service network into a multi-service network. In addition to traditional applications like e-mail,WWW-traffic, or file transfer, future generation networks (FGNs) will carry services with real-time constraints and stringent availability and reliability requirements like Voice over IP (VoIP), video conferencing, virtual private networks (VPNs) for finance, other real-time business applications, tele-medicine, or tele-robotics. Hence, quality of service (QoS) guarantees and resilience to failures are crucial characteristics of an FGN architecture. At the same time, network operations must be efficient. This necessitates sophisticated mechanisms for the provisioning and the control of future communication infrastructures. In this work we investigate such echanisms for resilient FGNs. There are many aspects of the provisioning and control of resilient FGNs such as traffic matrix estimation, traffic characterization, traffic forecasting, mechanisms for QoS enforcement also during failure cases, resilient routing, or calability concerns for future routing and addressing mechanisms. In this work we focus on three important aspects for which performance analysis can deliver substantial insights: load balancing for multipath Internet routing, fast resilience concepts, and advanced dimensioning techniques for resilient networks. Routing in modern communication networks is often based on multipath structures, e.g., equal-cost multipath routing (ECMP) in IP networks, to facilitate traffic engineering and resiliency. When multipath routing is applied, load balancing algorithms distribute the traffic over available paths towards the destination according to pre-configured distribution values. State-of-the-art load balancing algorithms operate either on the packet or the flow level. Packet level mechanisms achieve highly accurate traffic distributions, but are known to have negative effects on the performance of transport protocols and should not be applied. Flow level mechanisms avoid performance degradations, but at the expense of reduced accuracy. These inaccuracies may have unpredictable effects on link capacity requirements and complicate resource management. Thus, it is important to exactly understand the accuracy and dynamics of load balancing algorithms in order to be able to exercise better network control. Knowing about their weaknesses, it is also important to look for alternatives and to assess their applicability in different networking scenarios. This is the first aspect of this work. Component failures are inevitable during the operation of communication networks and lead to routing disruptions if no special precautions are taken. In case of a failure, the robust shortest-path routing of the Internet reconverges after some time to a state where all nodes are again reachable – provided physical connectivity still exists. But stringent availability and reliability criteria of new services make a fast reaction to failures obligatory for resilient FGNs. This led to the development of fast reroute (FRR) concepts for MPLS and IP routing. The operations of MPLS-FRR have already been standardized. Still, the standards leave some degrees of freedom for the resilient path layout and it is important to understand the tradeoffs between different options for the path layout to efficiently provision resilient FGNs. In contrast, the standardization for IP-FRR is an ongoing process. The applicability and possible combinations of different concepts still are open issues. IP-FRR also facilitates a comprehensive resilience framework for IP routing covering all steps of the failure recovery cycle. These points constitute another aspect of this work. Finally, communication networks are usually over-provisioned, i.e., they have much more capacity installed than actually required during normal operation. This is a precaution for various challenges such as network element failures. An alternative to this capacity overprovisioning (CO) approach is admission control (AC). AC blocks new flows in case of imminent overload due to unanticipated events to protect the QoS for already admitted flows. On the one hand, CO is generally viewed as a simple mechanism, AC as a more complex mechanism that complicates the network control plane and raises interoperability issues. On the other hand, AC appears more cost-efficient than CO. To obtain advanced provisioning methods for resilient FGNs, it is important to find suitable models for irregular events, such as failures and different sources of overload, and to incorporate them into capacity dimensioning methods. This allows for a fair comparison between CO and AC in various situations and yields a better understanding of the strengths and weaknesses of both concepts. Such an advanced capacity dimensioning method for resilient FGNs represents the third aspect of this work.
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.
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.
Diagnostic Case Based Training Systems (D-CBT) provide learners with a means to learn and exercise knowledge in a realistic context. In medical education, D-CBT Systems present virtual patients to the learners who are asked to examine, diagnose and state therapies for these patients. Due a number of conflicting and changing requirements, e.g. time for learning, authoring effort, several systems were developed so far. These systems range from simple, easy-to-use presentation systems to highly complex knowledge based systems supporting explorative learning. This thesis presents an approach and tools to create D-CBT systems from existing sources (documents, e.g. dismissal records) using existing tools (word processors): Authors annotate and extend the documents to model the knowledge. A scalable knowledge representation is able to capture the content on multiple levels, from simple to highly structured knowledge. Thus, authoring of D-CBT systems requires less prerequisites and pre-knowledge and is faster than approaches using specialized authoring environments. Also, authors can iteratively add and structure more knowledge to adapt training cases to their learners needs. The theses also discusses the application of the same approach to other domains, especially to knowledge acquisition for the Semantic Web.
A complete simulation system is proposed that can be used as an educational tool by physicians in training basic skills of Minimally Invasive Vascular Interventions. In the first part, a surface model is developed to assemble arteries having a planar segmentation. It is based on Sweep Surfaces and can be extended to T- and Y-like bifurcations. A continuous force vector field is described, representing the interaction between the catheter and the surface. The computation time of the force field is almost unaffected when the resolution of the artery is increased.
The mechanical properties of arteries play an essential role in the study of the circulatory system dynamics, which has been becoming increasingly important in the treatment of cardiovascular diseases. In Virtual Reality Simulators, it is crucial to have a tissue model that responds in real time. In this work, the arteries are discretized by a two dimensional mesh and the nodes are connected by three kinds of linear springs. Three tissue layers (Intima, Media, Adventitia) are considered and, starting from the stretch-energy density, some of the elasticity tensor components are calculated. The physical model linearizes and homogenizes the material response, but it still contemplates the geometric nonlinearity. In general, if the arterial stretch varies by 1% or less, then the agreement between the linear and nonlinear models is trustworthy.
In the last part, the physical model of the wire proposed by Konings is improved. As a result, a simpler and more stable method is obtained to calculate the equilibrium configuration of the wire. In addition, a geometrical method is developed to perform relaxations. It is particularly useful when the wire is hindered in the physical method because of the boundary conditions. The physical and the geometrical methods are merged, resulting in efficient relaxations. Tests show that the shape of the virtual wire agrees with the experiment. The proposed algorithm allows real-time executions and the hardware to assemble the simulator has a low cost.
Object six Degrees of Freedom (6DOF) pose estimation is a fundamental problem in many practical robotic applications, where the target or an obstacle with a simple or complex shape can move fast in cluttered environments. In this thesis, a 6DOF pose estimation algorithm is developed based on the fused data from a time-of-flight camera and a color camera. The algorithm is divided into two stages, an annealed particle filter based coarse pose estimation stage and a gradient decent based accurate pose optimization stage. In the first stage, each particle is evaluated with sparse representation. In this stage, the large inter-frame motion of the target can be well handled. In the second stage, the range data based conventional Iterative Closest Point is extended by incorporating the target appearance information and used for calculating the accurate pose by refining the coarse estimate from the first stage. For dealing with significant illumination variations during the tracking, spherical harmonic illumination modeling is investigated and integrated into both stages. The robustness and accuracy of the proposed algorithm are demonstrated through experiments on various objects in both indoor and outdoor environments. Moreover, real-time performance can be achieved with graphics processing unit acceleration.
This thesis deals with the management and analysis of source code, which is represented in XML. Using the elementary methods of the XML repository, the XML source code representation is accessed, changed, updated, and saved. We reason about the source code, refactor source code and we visualize dependency graphs for call analysis. The visualized dependencies between files, modules, or packages are used to structure the source code in order to get a system, which is easily to comprehend, to modify and to complete. Sophisticated methods have been developed to slice the source code in order to obtain a working package of a large system, containing only a specific functionality. The basic methods, on which the visualizations and analyses are built on can be changed like changing a plug-in. The visualization methods can be reused in order to handle arbitrary source code representations, e.g., JAML, PHPML, PROLOGML. Dependencies of other context can be visualized, too, e.g., ER diagrams, or website references. The tool SCAV supports source code visualization and analyzing methods.
This thesis is devoted to the study of computational complexity theory, a branch of theoretical computer science. Computational complexity theory investigates the inherent difficulty in designing efficient algorithms for computational problems. By doing so, it analyses the scalability of computational problems and algorithms and places practical limits on what computers can actually accomplish. Computational problems are categorised into complexity classes. Among the most important complexity classes are the class NP and the subclass of NP-complete problems, which comprises many important optimisation problems in the field of operations research. Moreover, with the P-NP-problem, the class NP represents the most important unsolved question in computer science. The first part of this thesis is devoted to the study of NP-complete-, and more generally, NP-hard problems. It aims at improving our understanding of this important complexity class by systematically studying how altering NP-hard sets affects their NP-hardness. This research is related to longstanding open questions concerning the complexity of unions of disjoint NP-complete sets, and the existence of sparse NP-hard sets. The second part of the thesis is also dedicated to complexity classes but takes a different perspective: In a sense, after investigating the interior of complexity classes in the first part, the focus shifts to the description of complexity classes and thereby to the exterior in the second part. It deals with the description of complexity classes through leaf languages, a uniform framework which allows us to characterise a great variety of important complexity classes. The known concepts are complemented by a new leaf-language model. To a certain extent, this new approach combines the advantages of the known models. The presented results give evidence that the connection between the theory of formal languages and computational complexity theory might be closer than formerly known.