Master's Thesis
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- 360 Grad (1)
- 360 degree (1)
- Adhäsion (1)
- Augmented Reality (1)
- Ausrichtungswerkzeug (1)
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Today, augmented reality is becoming more and more important in several areas like industrial sectors, medicine, or tourism. This gain of importance can easily be explained by its powerful extension of real world content. Therefore, augmented realty became a way to explain and enhance the real world information. Yet, to create a system which can enhance a scene with additional information, the relation between the system and the real world must be known. In order to establish this relationship a commonly used method is optical tracking. The system calculates its relation to the real world from camera images. To do so, a reference which is known is needed in the scene to serve as an orientation. Today, this is mostly a 2D-marker or a 2D-texture. These are placed in the real world scenery to serve as a reference. But, this is an intrusion in the scene. That is why it is desirable that the system works without such an additional aid. An strategy without manipulating the scene is object-tracking. In this approach, any object from the scene can be used as a reference for the system. As an object is far more complex than a marker, it is harder for the system to establish its relationship with the real world. That is why most methods for 3D-object-tracking reduce the object by not using the whole object as reference. The focus of this thesis is to research how a whole object can be used as a reference in a way that either the system or the camera can be moved in any 360 degree angle around the object without loosing the relation to the real world. As a basis the augmented reality framework, the so called VisionLib, is used. Extensions to this system for 360 degree tracking are implemented in different ways and analyzed in the scope of this work. Also, the different extensions are compared. The best results were achieved by improving the reinitialization process. With this extension, current camera images of the scene are given to the system. With the hek of these images, the system can calculate the relation to the real world faster in case the relation went missing.
Heat exchangers are used for thickening of various products or desalination of saltwater. Nevertheless, they are used as cooling unit in industries. Thereby, the stainless steel heat transferring elements get in contact with microorganism containing media, such as river water or saltwater, and corrode. After at least two years of utilization the material is covered with bacterial slime called biofilm. This process is called biofouling and causes loss in efficiency and creates huge costs depending on cleaning technique and efficiency. Cleaning a heat exchanger is very expensive and time consuming. It only can be done while the device is out of business.
Changing the surface properties of materials is the best and easiest way to lengthen the initial phase of biofilm formation. This leads to less biofouling (Mogha et al. 2014).
Thin polymer films as novel materials have less costs in production than stainless steel and are easy to handle. Furthermore, they can be functionalzed easily and can be bougth in different sizes all over the world. Because of this, they can reduce the costs of cleaning techniques and lead to a longer high efficiency state of the heat exchanger. If the efficiency of the heat exchanger decreases, the thin polymer films can be replaced.
For a successful investigation of the microbial and the process engineering challenges a cooperation of Technical University of Kaiserslautern (chair of seperation science and technology) and University of Koblenz-Landau (working goup microbiology) was established.
The aim of this work was design engineering and production of a reactor for investigation of biofouling taking place on thin polymeric films and stainless steel. Furthermore, an experimental design has to be established. Several requirements have to be applied for these tasks. Therefore, a real heat exchanger is downscaled, so the process parameters are at least comparable. There are many commercial flow cell kits available. Reducing the costs by selfassembling increased the number of samples, so there is a basis for statistic analysis. In addition, fast and minimal invasive online-in-situ microscopy and Raman spectroscopy can be performed. By creating laminary flow and using a weir we implemented homogenous inflow to the reactors. Reproduceable data on biomass and cell number were created.
The assessment of biomass and cell number is well established for drinking water analysis. Epifluorescense microscopy and gravimetric determination are the basic techniques for this work, too. Differences in cell number and biomass between surface modifications and materials are quantified and statistically analysed.
The wildtype strain Escherichia coli K12 and an inoculum of 500 ml fresh water were used to describe the biofouling of the films. Thereby, we generated data with natural bacterial community in unknown media properties and data with well known media properties, so the technical relevance of the data is given.
Free surface energy and surface roughness are the first attachment hurdles for bacteria. These parameters were measured according to DIN 55660 and DIN EN ISO 4287. The materials science data were correlated with the number of cells and the biomass. This correlation acts as basal link of biofouling as biological induced parameter to the material properties. Material properties for reducing the biofouling can be prospected.
By using Raman spectroscopy as a cutting edge method future investigations could be shortened. If biomass or cell number can be linked with the spectra, new functional materials can be investigated in a short time.
This thesis conducts a text and network analysis of criminological files. The specific focus during the research is the field money laundering. The analysis showed the most important concepts present in the text which were classified in eleven different classes. The relationships of those concepts were analysed using ego networks, key entity identification and clustering. Some of the statements given about money laundering could be validated by the findings of this analysis and their interpretation. Specific concepts like banks and organizations as well as foreign subsidiaries were identified. Aggregating these concepts with the statements in chapter 1.4.3 on the circular process of money laundering it can be stated that different organizations and individuals, present in the criminological files, were placing money through different banks, organizations and investments in the legal financial market. At last this thesis tries to validate the benefits of the used tools for the kind of conducted research process. An estimation on ORA's and Automap's applicability for this kind of research is given in the end.
Einfluss eines Ausrichtungswerkzeugs auf die Bedienbarkeit in unbeaufsichtigten Eyetrackingsystemen
(2015)
Eye gaze trackers are devices that can estimate the direction of gaze of a person. Among usability testing eye tracking also allows persons with decreased limb mobility to control or to interact with the computer. The quality and availability of eye tracking equipment has been increasing while costs have been decreasing. This development leads to entering new markets by using eye tracking as an additional input dimension for a variety of applications. Up to now eye tracking has been supervised by qualified experts, who assured that the important conditions like position in front of the eye tracking device, calibration and light conditions has been kept, while using.
This thesis examines an adjustment tool, which is helping the user to adjust in front of the eye tracker and helping to keep this position during the experiment. Furthermore the accuracy while moving the head has been analysed. In this experiment an remote eye gaze tracker has been used to control a game character in the video game called 'Schau Genau!'. The goal was to determine whether the game is playable without the barrier of adjusting and calibration. The results show that adjusting in front of an eye tracker is not a problem, keeping this position is. Small changes of the head position after the calibration process leads to a lack of accuracy. Giving up the calibration and using someone else calibration shows way bigger deviation. Additional head movement increases error rate and makes controlling more difficult.
In current research of the autonomous mobile robots, path planning is still a very important issue.
This master's thesis deals with various path planning algorithms for the navigation of such mobile systems. This is not only to determine a collision-free trajectory from one point to another. The path should still be optimal and comply with all vehicle-given constraints. Especially the autonomous driving in an unknown and dynamic environment poses a major challenge, because a closed-loop control is necessary and thus a certain dynamic of the planner is demanded.
In this paper, two types of algorithms are presented. First, the path planner, based on A*, which is a common graph search algorithm: A*, Anytime Repairing A*, Lifelong Planning A*, D* Lite, Field D*, hybrid A*. Second, the algorithms which are based on the probabilistic planning algorithm Rapidly-exploring Random Tree (Rapidly-exploring Random Tree, RRT*, Lifelong Planning RRT*), as well as some extensions and heuristics. In addition, methods for collision avoidance and path smoothing are presented. Finally, these different algorithms are evaluated and compared with each other.
Im Rahmen dieser Arbeit wird untersucht, wie sich Modellfehler auf die Positionsgenauigkeit und Handhabbarkeit beim Rangieren mit einem Fahrerassistenzsystem auswirken. Besonderer Wert wird dabei auf die Bestimmung von Fehlergrenzen gelegt. Es wird der Frage nachgegangen, wie groß der Eingangsfehler sein darf, damit die Assistenz noch hinreichende Qualitätseigenschaften hinsichtlich ihrer Präzision und Robustheit aufweist. Dazu erfolgt zunächst eine quantitative Betrachtung der Fehler anhand des kinematischen Modells. Danach wird eine qualitative Betrachtung anhand von systematischen Experimenten durchgeführt. Es wird zunächst ein Controller entwickelt, mit dem sich ein Manöver mithilfe der visuellen Informationen der Assistenz simulieren lässt.
Dann wird eine Methode vorgestellt, mit deren Hilfe man das Manöver anhand definierter Fehlergrenzen bewerten kann. Um einen großen Raum möglicher Fehlerkombinationen effizient zu durchsuchen, wird das probabilistische Verfahren des Annealed Particle Filters benutzt. Mithilfe einer Testumgebung werden schließlich systematische Experimente durchgeführt. Zur weiteren Evaluation des Assistenzsystems in einer kontrollierten Umgebung erfolgte in Zusammenarbeit mit dem Fraunhofer ITWM in Kaiserslautern die Portierung des Assistenzsystems auf die dortige Simulationsumgebung RODOS.
In der vorliegenden Arbeit sollen weltweit herrschende inhaltliche Ausprägungen und Schwerpunkte des Themengebiets "BMI" bzw. "GMI" mit Hilfe des Literatur-Reviews akademischer Artikel herausgearbeitet werden. Die festgestellten Beziehungen und Zusammenhänge sollen visualisiert und lokalisiert werden, um eine globale Sicht über das Thema herzustellen. Unter anderem sollen die in das finale Set aufgenommenen Artikel auf eine Korrelation zwischen BMI und Controlling bzw. Management hin überprüft werden. Als letzter Schritt soll eine Ableitung möglicher Forschungslücken unternommen werden.
This master- thesis investigates the topic of intercultural web design. Two websites from different countries are exemplarily compared. On the basis of cultural dimensions, cultural differences are presented on each respective website. The analysis particularly focuses on how detailed the respective website-designer and -operator regards their users" cultural differences and the creation of a cross-cultural web design. The analysis illustrates which cultural - and particularly intercultural - aspects of countries were taken into consideration in the design of the web sites. The investigation led to the conclusion that their implementation was not consequently executed for all web sites. Hence, this thesis offers suggestions for the improvement of aspects which are most important in intercultural web design.
The lasting hype around the mobile internet and the related technology of the mobile applications seem not to drop off. The immense economic potential of this market leads the businesses and ventures to continuously find new ways of monetization. The underlying causes of that phenomenon are rarely challenged. Scientific research in the field of "ubiquitous mobile" has not yet developed a clear overall picture of the causes and effect chains. Attempts of deriving causes by studies in related mass media such as the computer or the internet have been discussed controversially. By combining the research streams of media motive usage and the customer retention, this paper will present a new research model. Based on a quantitative survey in the German speaking the gained data proves the motives for mobility, information gathering and entertainment purposed to be the most important drivers of customer satisfaction in mobile applications. The paper also highlights a significant correlation between the customer satisfaction and the other determinants of customer retention.
Politische und gesellschaftliche Polarisierung ist ein interessantes Phänomen, über dessen Auswirkungen viele unterschiedliche, zum Teil auch gegensätzliche, Theorien existieren.
Polarisierung wird in der Literatur mit unterschiedlichen Methoden gemessen. Die vorliegende Arbeit gibt einen Überblick über existierende Polarisierungsmaße und es werden zwei neuartige Maße aus dem Gebiet der spektralen Graphentheorie vorgestellt. Anschließend werden die bekannten und die neu entwickelten Maße auf den LiquidFeedback-Datensatz der Piratenpartei Deutschland angewandt. Als Ergebnis lässt sich festhalten, dass die Maße teilweise zu unterschiedlichen Ergebnisse kommen. Dies liegt darin begründet, dass nicht alle Maße das Gleiche messen. Um zu verstehen was die einzelnen Maße aussagen, werden wesentliche Eigenschaften von Polarisierungsmaßen herausgearbeitet und es wird für jedes Maß dargelegt, welche Eigenschaften es erfüllt. Die angesprochenen Polarisierungsmaße beziehen sich auf die Entwicklung der Polarisierung zwischen Usern des LiquidFeedback-Systems. Bei der Betrachtung von einzelnen Personen und Abstimmungen fiel unter anderem auf, dass polarisierende Personen mehr Macht durch
Delegationen besitzen als die restlichen Personen und dass polarisierte Vorschläge circa doppelt so häufig umgesetzt werden.
In this thesis, we deal with the question if challenge, flow and fun in computer games are related to each other, and which influence the motivational, psychological components motivation of success, motivation of failure and the chance of success do have. In addition, we want to know if a free choice in the level of difficulty is the optimal way to flow. To examine these theories, a study based on an online survey was executed, in which the participants played the game “flOw“. The results were evaluated with the help of a two-factorial analysis of variance with repeated measurement and tests on correlation. Thereby we found out that there actually exists a relation between challenge, flow and fun and that motivation does matter indirectly.