Influence of magnetic field and ferromagnetic film thickness on domain pattern transfer in multiferroic heterostructures

Domains in BaTiO$_3$ induces a regular modulation of uniaxial magnetic anisotropy in CoFeB via an inverse magnetostriction effect. As a result, the domain structures of the CoFeB wedge film and BaTiO$_3$ substrate correlate fully and straight ferroelectric domain boundaries in BaTiO$_3$ pin magnetic domain walls in CoFeB. We use x-ray photoemission electron microscopy and magneto-optical Kerr effect microscopy to characterize the spin structure of the pinned domain walls. In a rotating magnetic field, abrupt and reversible transitions between two domain wall types occur, namely, narrow walls where the magnetization vectors align head-to-tail and much broader walls with alternating head-to-head and tail-to-tail magnetization configurations. We characterize variations of the domain wall spin structure as a function of magnetic field strength and CoFeB film thickness and compare the experimental results with micromagnetic simulations.Comment: 5 pages, 5 figure

Enabling Live Data Controlled Manual Assembly Processes by Worker Information System and Nearfield Localization System

AbstractExisting localization solutions cannot be directly integrated into production systems. This article describes a nearfield localization system which can be installed on tools due to its small dimensions. Live data controlled manual assembly processes are enabled. In combination with worker information systems, the manual assembly process can be supported more precisely compared to common systems. The benefits are shown within product-specific assembly scenarios. One benefit is enabling work out of sight (non-visible range) guided through a virtual model on a screen. Error prevention (zero-defect assembly) can be realized by monitoring and matching the actual position to the assembly location. Even without augmented reality devices, comparative 3-D representations of real and virtual world are feasible, supporting employees in mobile workshop with complex repairs. In particular, difficult accessibility can be easily determined when carrying out maintenance work by knowing the complete product structure

Accuracy and Immersion Improvement of Hybrid Motion Capture based Real Time Virtual Validation

AbstractUsing a digital human model for dynamic analysis is due to the high modelling complexity in digital environments not very prevalent. The movement of the worker is either unrealistic, or time-consuming to realize. Therefore, the need for research is a time saving possibility to explore virtual validation by a human model taking advantage of a nonetheless realistic movement design. To achieve this goal, we use an experimental setup including both a hybrid motion capture system and an interface for the connection to digital validation software. The motion capturing in connection along with the validation software allows real time modelling respectively tracking and therefore a realistic movement of the human model. To get good results while applying the motion capturing approach in mixed reality situations, it is necessary to have an exact registration between the real and virtual environment. Hence, the experimental setup must be designed for both. The key challenge here is to superimpose the CAD data with the real objects used for haptic feedback and better immersion. To realize an optimal registration we use a laser tracker solution

Earth observation in support of malaria control and epidemiology: MALAREO monitoring approaches

Malaria affects about half of the world's population, with the vast majority of cases occuring in Africa. National malaria control programmes aim to reduce the burden of malaria and its negative, socioeconomic effects by using various control strategies (e.g. vector control, environmental management and case tracking). Vector control is the most effective transmission prevention strategy, while environmental factors are the key parameters affecting transmission. Geographic information systems (GIS), earth observation (EO) and spatial modelling are increasingly being recognised as valuable tools for effective management and malaria vector control. Issues previously inhibiting the use of EO in epidemiology and malaria control such as poor satellite sensor performance, high costs and long turnaround times, have since been resolved through modern technology. The core goal of this study was to develop and implement the capabilities of EO data for national malaria control programmes in South Africa, Swaziland and Mozambique. High-and very high resolution (HR and VHR) land cover and wetland maps were generated for the identification of potential vector habitats and human activities, as well as geoinformation on distance to wetlands for malaria risk modelling, population density maps, habitat foci maps and VHR household maps. These products were further used for modelling malaria incidence and the analysis of environmental factors that favour vector breeding. Geoproducts were also transferred to the staff of national malaria control programmes in seven African countries to demonstrate how EO data and GIS can support vector control strategy planning and monitoring. The transferred EO products support better epidemiological understanding of environmental factors related to malaria transmission, and allow for spatio-temporal targeting of malaria control interventions, thereby improving the cost-effectiveness of interventions

Is cell segregation like oil and water: asymptotic versus transitory regime

Segregation of different cell types is a crucial process for the pattern formation in tissues, in particular during embryogenesis. Since the involved cell interactions are complex and difficult to measure individually in experiments, mathematical modelling plays an increasingly important role to unravel the mechanisms governing segregation. The analysis of these theoretical models focuses mainly on the asymptotic behavior at large times, in a steady regime and for large numbers of cells. Most famously, cell-segregation models based on the minimization of the total surface energy, a mechanism also driving the demixing of immiscible fluids, are known to exhibit asymptotically a particular algebraic scaling behavior. However, it is not clear, whether the asymptotic regime of the numerical models is relevant at the spatio-temporal scales of actual biological processes and in-vitro experiments. By developing a mapping between cell-based models and experimental settings, we are able to directly compare previous experimental data to numerical simulations of cell segregation quantitatively. We demonstrate that the experiments are reproduced by the transitory regime of the models rather than the asymptotic one. Our work puts a new perspective on previous model-driven conclusions on cell segregation mechanisms.Comment: 24 pages, 7+4 figure

Assessment of Metal Hydride Reactors as Thermal Management Enhancement of Hydrogen Fuel Cells in Electric Aircraft

Electrified propulsion systems have the potential to reduce the environmental impact of aviation. Hydrogen fuel cells as primary energy supplier are a promising technology to power the electrically-driven propulsors. However, the thermal management of fuel cells is challenging due to their high amount of excess heat energy at a typically low temperature level. This work investigates the cooling potential of metal hydride (MH) reactors to enhance the thermal management system (TMS) of low temperature fuel cells. As a secondary function, the MH reactor can serve as an emergency hydrogen supply. There are two operation concepts of MH reactors considered in this study. In the first operation concept, the MH acts as a heat sink by absorbing some share of the heat of the fuel cell. This decreases the amount of heat to be removed by the TMS. In the second operation concept, the MH reactor operates as a heat pump to enlarge the temperature difference in the heat transfer fluid cycle. This improves the performance of the heat exchanger of the TMS to reject heat to the ambient air. For both operation modes, a sizing of an MH reactor and a heat exchanger is performed to estimate the impact on the TMS. While an exemplary general aviation aircraft serves as calculation example, the results are also applicable to commuter and regional aviation aircrafts. The study shows, that MH reactors have the potential to reduce the size of the heat exchanger significantly. In quasi-continuous heat pump operation, an MH reactor allows a reduction of the heat exchanger dimensions of up to 8 %. If the maximum heat rejection during take-off determines the heat exchanger size, a reduction of even 39% is reasonable when the MH reactor operates as a heat sink

Überwachung isländischer Vulkane mit innovativen Fernerkundungs-Technologien und 3D Visualisierung

Die phreatomagmatische Eruption des isländischen Vulkans Eyjafjallajökull im Frühjahr 2010 hatte durch die Beeinträchtigung des europäischen Luftverkehrs einen enormen wirtschaftlichen Schaden verursacht. Basierend auf diesem Ereignis wird im Projekt IsViews (Iceland subglacial Volcanoes interdisciplinary early warning system) der wenige Kilometer entfernte Mýrdalsjökull mit dem subglazialen Zentralvulkan Katla untersucht. Ein erneuter Vulkanausbruch wird erwartet. Das interdisziplinär ausgerichtete Forschungsprojekt steht im Kontext von GMES. Zur Überwachung stehen eine Zeitreihe von TerraSAR-X (TSX) Daten seit 2010, optische Daten der RapidEye Satelliten sowie höchstaufgelöste HRSC Luftbilddaten zur Verfügung. Unterstützt wird das Monitoring der geodynamischen Prozesse mit kontinuierlichen Höhenmodellen aus der TanDEM-X Mission. Diese werden mit Hilfe von aktuellen LiDAR Daten verifiziert. Eine umfangreiche GIS-Datenbank wird regelmäßig erweitert, u.a. durch near real-time Stripmap TSX Szenen, aktuelle Seismik-und Wetterdaten sowie Informationen über die Gletscherdynamik. Im Sommer 2013 wurden auf dem Mýrdalsjökull zwei automatische GPS Stationen, drei Pegelstationen und am DLR neu entwickelte Top-Hat Reflektoren zur Erfassung der glazialen Bewegungsvorgänge aufgebaut. Die Reflektoren konnten auf experimentellen Staring Spotlight TSX Daten mit einer Bodenauflösung von wenigen Dezimetern identifiziert werden. Eine Höhendifferenz-Analyse von sieben TanDEM-X Szenen, aufgenommen zwischen September 2011 und Juni 2013, zeigt, dass es möglich ist mit diesen innovativen Daten Änderungen des Gletschervolumens sowie Eisdepressionen zu detektieren. Ziel des Projektes ist es Veränderungen der Gletscheroberfläche, ausgelöst durch subglaziale vulkanische Aktivitäten, automatisch zu erfassen. Ein satellitengestütztes near real-time Monitoring zur Früherkennung von Naturereignissen wird entwickelt und in eine internetbasierte 3D Visualisierungsumgebung integriert. Hierfür wurde bereits ein 3D Modell von ganz Island basierend auf 267 RapidEye Bildkacheln aus den Jahren 2011 und 2012 erstellt. Die hohe vulkanische Aktivität auf Island erlaubt, Anwendungen und Methoden mittels near real-time Fernerkundungs-und GIS-Daten für den Katastrophenschutz zu erproben und einzusetzen

A Pattern-based Approach to Quantitative Enterprise Architecture Analysis

Enterprise Architecture (EA) management involves tasks that substantially contribute to the operations of an enterprise, and to its sustainable market presence. One important aspect of this is the availability of services to customers. However, the increasing interconnectedness of systems with other systems and with business processes makes it difficult to get a clear view on change impacts and dependency structures. While management level decision makers need this information to make sound decisions, EA models often do not include quality attributes (such as availability), and very rarely provide quantitative means to assess them. We address these shortcomings by augmenting an information model for EA modeling with concepts from Probabilistic Relational Models, thus enabling quantitative analysis. A sample business case is evaluated as an example of the technique, showing how decision makers can benefit from information on availability impacts on enterprise business services