05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
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Item Open Access Inferring object hypotheses based on feature motion from different sources(2015) Fuchs, SteffenPerception systems in robotics are typically closely tailored to the given task, e.g., in typical pick-and-place tasks the perception systems only recognizes the mugs that are supposed to be moved and the table the mugs are placed on. The obvious limitation of those systems is that for a new task a new vision system must be designed and implemented. This master's thesis proposes a method that allows to identify entities in the world based on motion of various features from various sources. This is without relying on strong prior assumptions and to provide an important piece towards a more general perception system. While entities are rigid bodies in the world, the sources can be anything that allows to track certain features over time in order to create trajectories. For example, these feature trajectories can be obtained from RGB and RGB-D sensors of a robot, from external cameras, or even the end effector of the robot (proprioception). The core conceptual elements are: the distance variance between trajectory pairs is computed to construct an affinity matrix. This matrix is then used as input for a divisive k-means algorithm in order to cluster trajectories into object hypotheses. In a final step these hypotheses are combined with previously observed hypotheses by computing the correlations between the current and the updated sets. This approach has been evaluated on both simulated and real world data. Generating simulated data provides an elegant way for a qualitative analysis of various scenarios. The real world data was obtained by tracking Shi-Tomasi corners using the Lucas-Kanade optical flow estimation of RGB image sequences and projecting the features into range image space.Item Open Access Prozessbausteine(2014) Eberle, Hanna; Leymann, Frank (Prof. Dr.)Gegenwärtig existierenden Modellierungssprachen und Werkzeugen zur Umsetzung prozessbasierter Anwendungen liegt im Allgemeinen die Annahme eines zur Entwicklungszeit bekannten und in seiner Struktur vollständig ausmodellierten Prozessmodells zugrunde. Für Szenarien, in welchen eine prozessbasierte Anwendung neben stabilen, d.h. zur Modellierungszeit des Prozesses bekannten, auch durch dynamische, d.h. erst zur Anwendungslaufzeit geltende, Rahmenbedingungen beeinflusst wird, ist eine derartige statische Prozessmodellierung nur bedingt geeignet. In diesen Szenarien ist es vielmehr wünschenswert, (i) zur Entwicklungszeit bereits bekannte Prozessteile der Anwendung detailliert ausmodellieren zu können, und diese (ii) zur Laufzeit der Anwendung unter Berücksichtigung der zum Ausführungszeitpunkt geltenden dynamischen Rahmenbedingungen zum vollständigen Prozess der Anwendung zu integrieren. Das im Verlauf dieser Arbeit vorgestellte Konzept der Prozessbausteine setzt an diesem Punkt an und schafft ein Rahmenwerk für die Modellierung und Ausführung prozessbasierter Anwendungen unter Berücksichtigung sowohl stabiler als auch dynamischer Rahmenbedingungen. Kerngedanke des Konzepts ist die Abbildung stabiler Rahmenbedingungen zur Entwicklungszeit in Form teilweise unvollständiger Prozessmodelle, sogenannter Prozessbausteine. Zu einem späteren Zeitpunkt im Lebenszyklus der Anwendung werden diese Prozessbausteine dann, motiviert durch die jeweils geltenden dynamischen Rahmenbedingungen, mit weiteren Prozessbausteinen zum vollständigen Prozessmodell der Anwendung integriert. Zur vollständigen Unterstützung der Entwicklung von Anwendungen auf Grundlage dieses Konzepts umfasst die vorliegende Arbeit die Definition eines Metamodells für sowohl die Modellierung einzelner als auch die Repräsentation integrierter Prozessbausteine, die Beschreibung der Ausführung integrierter Prozessbausteine, sowie die Vorstellung einer Architektur für die Ausführung integrierter Prozessbausteine.Item Open Access Fragments of first-order logic over infinite words(2009) Diekert, Volker; Kufleitner, ManfredWe give topological and algebraic characterizations as well as language theoretic descriptions of the following subclasses of first-order logic for omega-languages: Sigma2, FO2, the intersection of FO2 and Sigma2, and Delta2 (and by duality Pi2 and the intersection of FO2 and Pi2). These descriptions extend the respective results for finite words. In particular, we relate the above fragments to language classes of certain (unambiguous) polynomials. An immediate consequence is the decidability of the membership problem of these classes, but this was shown before by Wilke and Bojanczyk and is therefore not our main focus. The paper is about the interplay of algebraic, topological, and language theoretic properties.Item Open Access Adaptive frameless raycasting for interactive volume visualization(2014) Weißer, ConstantinThere have been many successful attempts to improve ray casting and ray tracing performance in the last decades. Many of these improvements form important steps towards high-performance interactive visualisation. However, growing challenges keep pace with enhancements: display resolutions skyrocket with modern technology and applications become more and more sophisticated. With the limits of Moore's law moving into sight, there have been many considerations about speeding up well-known algorithms, including a plenitude of publications on frameless rendering. In frameless renderers sampling is not synchronised with display refreshes. That allows for both spatially and temporally varying sample rates. One basic approach simply randomises samples entirely. This increases liveliness and reduces input delay, but also leads to distorted and blurred images during movements. Dayal et al. tackle this problem by focusing samples on complex regions and by applying approximating filters to reconstruct an image from incoherent buffer content. Their frameless ray tracer vastly reduces latency and yet produces outstanding image quality. In this thesis we transfer the concepts to volume ray casting. Volume data often poses different challenges due to its lack of plains and surfaces, and its fine granularity. We experiment with both Dayal's sampling and reconstruction techniques and examine their applicability on volume data. In particular, we examine whether their adaptive sampler performs as well on volume data and which adaptions might be necessary. Further, we develop another reconstruction filter which is designed to remove artefacts that frequently occur in our frameless renderer. Instead of assuming certain properties due to local sampling rates and colour gradients, our filter detects artefacts by their age signature in the buffer. Our filter seems to be more targeted and yet requires only constant time per pixel.Item Open Access Feasibility analysis of using Model Predictive Control in Demand-Side Management of residential building(2020) Ramachandran Selvaraj, Sri VishnuThe energy systems are becoming smart recently with an increase in communication capabilities between producer, distributor and consumer. Also, many distributed renewable energy producers both in large and domestic scale are adding to the system day by day. Executing Smart Demand-Side Management (DSM) programs can help in providing financial benefits and stability of the energy system without compromising the comfort of end-users. Model Predictive Control (MPC) is an advanced method of process control that is used to control a process while satisfying a set of constraints. Due to its ability to predict future events and generate optimal control, it is widely used in process industries since the 1980s and in recent years it is introduced in power systems. This motivates to study the economic feasibility of using MPC in executing DSM for Residential building, to optimize the power consumption costs and stability of the energy system in the presence of local renewable energy sources (E.g., PV system). The main contribution of this thesis work is to measure the economic benefit of using MPC on DSM of household electricity consumption. A detailed study of modeling the demand side, i.e the appliances of a smart home, along with the domestic energy generators is done in the initial part. Apart from the physical properties of the renewable energy generators, the influence of external factors like weather, dynamic-pricing of electricity and changing user preference is also considered in the model. This formulated model is used to perform simulation of the residential building to generate an optimized energy consumption schedule and calculate the resulting economic benefits. The periodic changes in weather forecast and dynamic-prices are fed into the simulation to improve the prediction accuracy of the system. Lastly, the model is evaluated on a physical implementation to analyze its performance. There are multiple findings as part of the result of this thesis, like the economic benefit of using such a system will encourage many users to participate in Demand response programs, this in turn will help in the reduction of pollution originating from non-renewable energy generators.Item Open Access Analyse poröser Medien auf Basis von Kristalliten(2013) Straub, AlexanderEine Möglichkeit zur Simulation poröser Medien sind Modelle. Diese haben den Vorteil, dass sie computergestützt erstellt werden können und somit auch größere, aussagekräftigere Datensätze hervorbringen. In dieser Bachelor-Arbeit wird ein neuer Ansatz zur Bestimmung des Volumens und der Porösität vorgestellt, basierend auf einem Modell für Sandsteine. Dies war mit bisherigen Algorithmen nur unzureichend möglich, da durch Annäherung große Fehler entstehen. Der neue hier vorgestellte Ansatz wird direkt auf der Geometrie des Modells ausgeführt, somit werden fast keine Rechenfehler begangen. Dieser Ansatz lässt sich zudem durch Aufteilen in Unterprobleme und durch die Benutzung von Heuristiken effizient auf große Datensätze anwenden. Die Messergebnisse und die Folgerungen für Effizienz und Effektivität des Algorithmus werden anschließend aufgeführt und erläutert.Item Open Access Service Injection von TOSCA-basierten Diensten in Java-Anwendungen(2019) Kiefer, LeonViele Cloud Anwendungen bestehen aus mehreren Komponenten und Services, die miteinander kommunizieren. Die Topology and Orchestration Specification for Cloud Applications (TOSCA) definiert einen Standard, um solche Cloud Anwendungen zu beschreiben und zu managen. Um Cloud Services in lokalen Anwendungen zu verwenden, müssen abhängig von der verwendeten Kommunikationstechnologie und der Implementierung der Cloud Services Verbindungsinformationen ausgetauscht werden und spezielle Client Bibliotheken verwendet werden. Dies sorgt für eine hohe Komplexität und schlechte Wiederverwendbarkeit der Implementierung von lokalen Anwendungen. In dieser Arbeit wird ein Konzept vorgestellt, bei dem die komplexe und technologiespezifische Kommunikation nicht in der lokalen Anwendung implementiert wird. Stattdessen werden vorgefertigte Adapter für die jeweilige Technologie mit den passenden Verbindungsinformationen der externen Services in die lokale Anwendung injiziert. Es wird ein Programmiermodell vorgestellt mit dem diese lokalen Anwendungen entwickelt und bereitgestellt werden können. Externen Services werden automatisiert bereitgestellt, wenn diese von der lokalen Anwendung benötigt werden. Die Umsetzbarkeit des Konzeptes wird anhand einer prototypischen Implementierung in Java und der Verwendung von TOSCA-basierten Cloud Services validiert.Item Open Access Individual characteristics of successful coding challengers(2017) Wyrich, MarvinAssessing a software engineer's problem-solving ability to algorithmic programming tasks has been an essential part of technical interviews at some of the most successful technology companies for several years now. Despite the adoption of coding challenges among these companies, we do not know what influences the performance of different software engineers in solving such coding challenges. We conducted an exploratory study with software engineering students to find hypothesis on what individual characteristics make a good coding challenge solver. Our findings show that the better coding challengers have also better exam grades and more programming experience. Furthermore, conscientious as well as sad software engineers performed worse in our study.Item Open Access Economic feasibility analysis of vehicle-to-grid service from an EV owner's perspective in the german electricity market(2020) Malya, Prasad PrakashThe increasing number of Electrical Vehicles (EV) has led to a tremendous amount of inac- cessible electric energy stored in the EV batteries. Vehicle-to-grid (V2G) services can utilize this energy to profit the EV owners’ and stabilize the grid during faults and fluctuations. This thesis presents a novel way of estimating the profitability of V2G from the EV owner’s perspective. The main contribution of this thesis is the formulation of a profit model that includes the EV battery degradation due to V2G. The work done so far considers fixed battery degradation cost, whereas in this work, an online battery degradation model is used. This model takes into account the parameters that represent real-life scenarios resulting in more accurate battery degradation estimation. The V2G profit model uses the electricity price signal from the German energy market for the year 2019 and estimates the annual profit. The first part of the thesis calculates the profitability of V2G, where EV can participate freely in energy arbitrage. This analysis explores the range of profit when EV participates in V2G purely based on the EV owner’s discretion. A sensitivity analysis is done with respect to battery capacity, battery efficiency, and driving distance. The second part of the thesis evaluates the profitability of EV participating in the German energy market’s frequency regulation ancillary service.=. The analysis compares the profitability of EV participating in primary, secondary, and tertiary frequency regulation services. The results of this thesis provide several findings, the potential profit from V2G services should encourage EV owners’ to participate in the V2G services. Additionally, participating in V2G service can extend the life of the battery. However, this depends on the battery technology and battery usage during V2G services. Ancillary services provide higher potential profit compared to energy arbitrage because of the high remuneration scheme. The ancillary services with both capacity and energy payment result in higher profit compared to ancillary services with only capacity payment.Item Open Access Control-plane consistency in software-defined networking: distributed controller synchronization using the ISIS² toolkit(2015) Strauß, JanSoftware-defined Networking (SDN) is a recent approach in computer networks to ease the network administration by separating the control-plane and the data-plane. The data-plane only forwards packets according to certain rules specified by the control-plane. The control-plane, implemented by a software called controller, determines the forwarding rules based on a global view of the network. In order to increase fault tolerance and to eliminate a possible performance bottleneck, the controller can be distributed. The synchronization of the data that holds the global view is conventionally realized using distributed key-value stores offering a fixed consistency semantic, not respecting the heterogeneous consistency requirements of the data items in controller state. The virtual synchrony model, an alternative approach to the commonly used state machine replication method, offers a more flexible solution that can result in higher performance when certain assumptions on the data kept in controller state can be made. In this thesis a distributed controller based on OpenDaylight, a state-of-the-art SDN controller and the ISIS² library, that implements the virtual synchrony model, is proposed. The modular architecture of the proposed controller and the usage of a platform independent data model allows to extend or replace parts of the system. The implementation of the distributed controller is described and the macro and micro performance is evaluated with benchmarks.