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Die subjektive Wahrnehmung des Pokerspiels : kognitive Verzerrungen und interindividuelle Differenzen bei einem Spiel mit Glücks- und Geschicklichkeitsanteilen
Get PDFThe study explores the question if poker represents a game of chance or of skill, and whether there are differences between average and expert players with regard to the subjective perception of poker. In total n = 300 subjects played computer-based 60 hands of the poker variant Texas Hold'em No Limit in groups of six participants. In each unit, three average players and three expert players took part. A predefined card deck was identical in each experiment to control the factor of chance in the game and allowed differentiated card qualities. The subjects provided informations via questionnaires about opinions and beliefs related to poker and with regard to the specific session. Results show that experts were unable to reach a significantly higher final cash balance than average players. The biggest influence on the outcome of the game had the quality of cards. Experts were more likely to show attitudes that view poker as a sport or competition and had a higher confidence in success
Advanced Inverse Modeling of Sediment Thermal Diffusion Processes : Reconstructing Temporal Variant Boundary Conditions for the One-Dimensional Heat Equation
Get PDFTemperatures in marine sediments are driven by the geothermal heat flow from the Earth's crust and the evolution of the bottom water temperature. Mathematically, the temperature field can be modeled with the heat equation, a Robin boundary condition at the sediment-water interface, and a Neumann condition at the lower boundary. Given the thermal properties of the sediment and a model for the bottom water temperature function the forward problem is well-posed. The inverse problem, i.e. reconstructing the bottom water temperature function from measurements of the sediment temperature, on the other hand is ill-posed; the parameterized model is non-linear but low-dimensional. Different Newton-linke methods, as well as a linear fitting approach with Tikhonov minimization, and a Markov Chain Monte Carlo method are shown and their performances for this problem are compared. The algorithms work differently well on this problem, and regularising methods are not necessarily better. The heuristic linear fitting has the best accuracy in reasonable computing time, while the Markov Chain Monte Carlo method has proven convergence for enlarging ensembles
On-chip Mammalian Cell Cultivation and Monitoring
Get PDFThe biological and medical progress is, among other factors, also enabled by powerful analysis devices. In the future, new tools will be based on microfluidics to assay mammalian cells. In this thesis, two concepts are discussed for the on-chip cultivation of adherent mammalian cells. Both concepts contain porous membranes to supply the cells with nutrients and gases by diffusion. The successful on-chip passaging is shown with MDCK- and HaCaT cells over 48 h and 14 days, respectively. The cell monitoring is limited to the measurement of oxygen uptake of cells which indicates their metabolism. The oxygen consumption rate is determined by measuring the decay of the oxygen concentration inside a closed microfluidic chip. With this system, the oxygen consumption rate of HaCaT cells is determined for different temperatures. The discussed concepts and results show that microfluidic devices are well suited for on-chip cell cultivation and monitoring despite their requirements
Development and qualification of deployable membranes for space applications
Get PDFDeployment systems for innovative space applications such as solar sails require technology for a controlled and autonomous deployment in space. Before employing such technology for a dedicated mission, it is necessary to demonstrate its reliability with a Technology Readiness Level (TRL) of six or higher. On the example of the design implemented in the Gossamer-1 project of the German Aerospace Center (DLR), a stowing and deployment process for large deployable membranes mainly considered for solar sailing is analyzed and tested. It is based on a combination of zig-zag folding and coiling of triangular sail segments spanned between crossed booms. Possible membrane materials are evaluated and a deployment technique is explored through theoretical analysis and tests in order to verify their functionality for large membrane space systems. The requirements for membranes that are exposed to the space environment are studied and the materials are analyzed regarding their resistance against atomic oxygen, radiation and their thermal properties. The folding geometry and force progressions are described mathematically. Load introduction aspects, the stress-strain state and the billowing of the deployed membrane are analyzed with finite element models. The folding lines were examined with microscopes, and their impact on thermal behavior is shown by analytical analysis. The membrane and deployment mechanisms were manufactured and integrated in an ISO 8 clean room environment, and the deployment process was verified in an extensive test campaign. It ranged from component level to system level and included mechanical vibration, static acceleration, fast decompression, thermal vacuum and laboratory deployment tests. It is shown that state-of-the-art aluminum-coated polyimide foils are sufficient for a demonstration of deployment technology in an Low Earth Orbit (LEO) and that coating systems based on a combination of aluminum, silicon oxide and titanium oxide enhance the membrane properties for solar sails. The model of the deployment force progression under zero gravity shows a tendency that the loads are transferred along the cathetus of the sail segments. The finite element models show generally low stresses in the deployed membrane and interface forces on the order of several Newtons for a 25m2 membrane. The analysis of the folding lines reveals that coatings in this region are damaged, and that hot spots can occur due to multiple reflections. The verification testing showed the general suitability of the membrane and of the deployment strategy itself. Materials, mechanisms, and a stowing and deployment strategy are presented that enable the controlled and autonomous membrane deployment for space sails. While the analysis presented is applied on a sail with an edge length of about 5 m, it allows an analysis of other configurations as well. This is of particular interest because currently-considered solar sails are about one order of magnitude bigger. With the environmental tests conducted, the membrane-related aspects of the deployment technology are on TRL six for a 25m2 LEO deployment demonstrator. The deployment strategy is scalable and materials are available that can be used for bigger solar sails as well. With respect to membrane-related aspects there is nothing to prevent the development of full-scale solar sails
Energy aware task allocation algorithms for wireless sensor networks
Get PDFComplex wireless sensor network (WSN) applications, such as those in Internet of things or in-network processing, are pushing the requirements of energy efficiency and long-term operation of the network drastically. Energy aware task allocation becomes crucial to extend the network lifetime, by efficiently distributing the tasks of applications among sensor nodes. Although task allocation has been deeply studied in wired systems, the resulting approaches are insufficient for WSNs due to limited battery resources and computing capability of WSN nodes, as well as the special wireless communication. This work focuses on designing energy aware task allocation algorithms to extend the network lifetime of WSNs. More precisely, this work firstly proposes a centralized static task allocation algorithm (CSTA) for cluster based WSNs. Since a WSN application can be modeled by a directed acyclic graph (DAG), the task allocation problem is formulated as partitioning the modeled DAG graph into two subgraphs: one for the slave node and the other for the master node. By using a binary vector variable to represent the partition cut, CSTA formulates the problem of maximizing network lifetime as a binary integer linear programming (BILP) problem. It provides one fixed time invariant partition cut (task allocation solution) for each slave node to balance the workload distribution of tasks. Moreover, motivated by the fact that using multiple partition cuts can achieve more balanced workload distribution, this work extends CSTA to a centralized dynamic task allocation algorithm, CDTA. By using a probability vector variable to stand for partition cuts with different weights, CDTA formulates the dynamic task allocation problem as a linear programing (LP) problem. Due to the high complexity of centralized algorithms, this work further proposes a very lightweight distributed optimal on-line task allocation algorithm (DOOTA). Through an indepth analysis, it proves that the optimal task allocation solution consists of at most two partition cuts for each slave nodes. Based on this analysis, DOOTA enables each slave node to calculate its own optimal task allocation solution by negotiating with the master node with a very short time. These contributions significantly improve the application performance for WSNs, but also for other domains, e.g, mobile edge/fog computing. Furthermore, the proposed task allocation algorithms are extended for different task scenarios and network structures, i.e., applications with conditional tasks, joint local and global applications and multi-hop mesh network. Given a condition triggered application, it is modeled by a DAG graph with conditional branches. This conditional DAG is further decomposed into multiple stationary DAG graphs without conditional branches according to the satisfaction probability of each condition. Based on this modeling, a static and a dynamic condition triggered task allocation algorithms (SCTTA and DCTTA) are proposed by considering the multiple stationary DAG simultaneously. Targeting the joint local and global applications, this work designs a static and a dynamic joint task allocation algorithms, SJTA and DJTA, based on BILP and LP, respectively. The modeling of local task allocation problem does not change, while the global task allocation problem is modeled by dividing the global DAG graph into different subgraphs mapping to the slave and master nodes. Besides the extensions for different task scenarios, this work presents a dynamic task allocation algorithm for multi-hop mesh networks (DTA-mhop) as well. The corresponding task allocation problem is modeled by dividing the DAG graph of each sensor node into multiple subgraphs mapping to itself, the routing and sink nodes. By using the summation of assigned tasks for each node, DTA-mhop formulates the lifetime maximization as a LP problem. The proposed task allocation algorithms are firstly evaluated using simulations and real WSN applications, in terms of network lifetime increase and algorithm runtime. In order to investigate the algorithm's performance in realistic scenarios, the CSTA, CDTA and DOOTA algorithms are implemented in a real WSN based on the OpenMote platform. Both the simulation and implementation results show that the network lifetime can be dramatically extended. Remarkably, the network lifetime improvements are more significant for addressing complex applications. The proposed task allocation algorithms are therefore suitable for WSNs, and they can also be easily adapted to other wireless domains
Entwicklung von Niederdruck-Carbonitrierprozessen zur Festigkeitssteigerung hochbelasteter Bauteile
Get PDFLow pressure carburizing offers the ability to produce bright-metallic surfaces without unwanted internal oxidation known from carburizing at atmospheric pressure but with lower consumption of hydrocarbon Grä01 . The expected increase in fatigue life of low pressure carburized parts compared to gas-carburized parts could not be achieved due to other side-effects than internal oxidation Cla03 . Case-hardening steels of the grades 18CrNiMo7-6, 20MoCrS4 and 20CrMo4 were tested with different approaches to dilute or even prevent these side-effects. Two types of furnaces were used to derive results, which are instantly applicable in industrial scale production. The first one was set up for research at the IWT in Bremen, Germany (Brand: Ipsen, type: RVTC). The second one is in use in industrial scale production and property of Wegener Härtetechnik GmbH located in Homburg, Germany (Brand: ALD, type: ModulTherm). In this paper the development of process strategies is presented, which exploit the potential of low pressure carburizing that could not be obtained in the past. Additionally, results relevant for operators are presented to show the assignability between the two types of furnaces and to give examples of conditioning and interdependencies in low pressure carbonitriding processes
Genomic Analyses of Polysaccharide Utilization in Marine Flavobacteriia
Get PDFMarine algae convert a substantial fraction of fixed carbon dioxide into various polysaccharides. Flavobacteriia that are specialized on algal polysaccharide degradation feature genomic clusters termed polysaccharide utilization loci (PULs). Since knowledge on extant PUL diversity is sparse, we sequenced the genomes of 53 North Sea Flavobacteriia. We obtained 400 PULs, suggesting usage of a large array of polysaccharides, including laminarin, A A /-- and A A -mannans, fucose-, xylose-, galactose-, rhamnose- and arabinose-containing substrates, pectins, and chitins. Many of the PULs exhibit new genetic architectures and suggest substrates rarely described for marine environments. The isolates' PUL repertoires often differed considerably within genera, corroborating ecological niche-associated glycan partitioning. Polysaccharide uptake in Flavobacteriia is mediated by SusCD-like transporter complexes. Respective protein trees revealed clustering according to polysaccharide specificities predicted by PUL annotations rather than phylogenetic affiliation. Using the trees, we analyzed expression of SusC/D homologs in multiyear phytoplankton bloom-associated metaproteomes and found indications for profound changes in microbial utilization of laminarin, A A /--glucans, ß-mannan and sulfated xylan. We hence suggest the suitability of SusC/D-like transporter protein expression within heterotrophic bacteria as a proxy for the temporal utilization of discrete polysaccharides
An automated hierarchical eXtended finite element approach for multiphysics problems involving discontinuities
Get PDFIn this thesis, a hierarchical eXtended finite element method for the modeling and numerical simulation of multiphysics problems and its implementation into a framework that uses automated code generation is presented. The approach consists of introducing hierarchically ordered level set functions, motivated by the structure of the considered problem, to decompose a given hold-all domain into several subdomains. The decomposition is guaranteed to be geometrically consistent which means that no overlapping regions or voids can arise. Mathematically, the approach decouples the computational mesh from the physical domains and, thereby, allows for large deformations and topological changes, such as the rise of (new) subdomains. At domain boundaries, quantities, or their gradient, may be modeled discontinuously and eXtended approximation spaces are introduced for the (sharp) representation of such features on the discrete level. The enrichment is realized by Heaviside functions which are defined subject to the hierarchical level set functions and, hence, introduce additional basis functions and coefficients locally at the respective (sub)domain boundary. For imposing interface and boundary conditions, the Nitsche method is used. By design, the developed approach is well suited to be implemented using automated code generation. As a result, the hierarchical eXtended finite element method is implemented as toolbox miXFEMfor the FEniCS framework. Therefore, the core components of FEniCS are significantly extended and new methods (e.g. the subdivision of elements and the assembling of tensors) are added. As the evolution of interfaces is often part of the problem, the framework miXFEMis supplemented by a level set toolbox providing maintaining methods such as reinitialization and volume correction as well as methods for computing a non-material velocity field. The method and its implementation is validated against several examples and then used for the modeling and simulation of different real-world applications in 2d and 3d. Since this thesis is motivated by several research projects where melting and solidification processes are of interest, we focus on these kind of problems and present results for a thermal upsetting process and different welding processes. However, due to the generality and flexibility of the developed framework, it can be used to rapidly implement and simulate problems from different areas such as multiphase flow or other problems with evolving geometries
Gestaltung eines E-Portfolio-Konzepts in der Berufsorientierung
Get PDFDie vorliegende Arbeit beschreibt den Gestaltungsprozess eines E-Portfolio-Konzepts auf der Basis eines designbasierten Forschungsvorgehens im Themenbereich der Berufsorientierung. In mehreren iterativ angelegten Zyklen wurde in Zusammenarbeit mit Lehrkräften und Schüler*innen an allgemeinbildenden Schulen ein Konzept entwickelt, das die Potenziale digitaler Medien mit denen des Portfolioâ Ansatzes zusammenführt. Einerseits umfasst das E-Portfolio-Konzept auf technischer Ebene ein Online-Portfolio, in dem insbesondere Schüler*innen ihre Erlebnisse im Rahmen von Berufsorientierungsprozessen multimedial dokumentieren und reflektieren können. Andererseits umfasst das Konzept exemplarisch gestaltete didaktische Einsatzszenarien sowohl für Lehrkräfte als auch anderes pädagogisches Fachpersonal. Zusätzlich konnte, die methodische Ebene der Arbeit betreffend, ein wissenschaftliches Vorgehensmodell nach dem Design-Based Research-Ansatz entwickelt und auf seine Tragfähigkeit überprüft werden
Intrinsische Selbstheilung von Beschichtungssystemen
Get PDFIn the present dissertation, two novel polyurethane-polyurea-based polymeric materials equipped with a high number of reversible hydrogen bonds (HBs) were examined in detail and characterized for their intrinsically self-healing properties. The chemical (covalent bonds) and physical (HB) network density of the polymers was varied by the self-healing reagent 1- (2-aminoethyl) imidazolidone (UDETA). Two different stimuli were identified for successful self-healing - increased relative humidity (23 degree C, 22-90 % RH) and elevated temperature (80-130 degree C). For self-healing at room temperature the presence of reversible HBs which provide higher molecular dynamics of the binding partners for self-healing process after bond breakage is of central importance. This circumstance was experimentally confirmed by the (temperature)-modulated differential scanning calorimetry (MDSC) measurement. It was found that the polymer absorbed water which is strongly bonded via HB within the polymeric network. This water causes a plastification of the material. Time domain Nuclear Magnetic Resonance (TD-NMR) measurements showed that with increasing UDETA content, a higher mobile fraction is present in the polymer. The mobility of the polymeric chains can be increased by incorporation of water, achieving a positive effect on the self-healing efficiency of the polymers. The importance and availability of different HB species in the polymer were examined in detail with Fourier Transformation Infrared (FT-IR) spectroscopy after equilibrating the samples with D2O. With increasing UDETA content the self-healing polymers show an increasing number of free carbonyl groups which were not bound via HB with varying strength. This work has successfully demonstrated the synthesis of intrinsically self-healing polyurethane-polyurea polymers and elucidated fundamental mechanistic questions of self-healing. The investigations underline the high potential of this investigated coating in a potential application