Attention-controlled acquisition of a qualitative scene model for mobile robots

Haasch A. Attention-controlled acquisition of a qualitative scene model for mobile robots. Bielefeld (Germany): Bielefeld University; 2007.Robots that are used to support humans in dangerous environments, e.g., in manufacture facilities, are established for decades. Now, a new generation of service robots is focus of current research and about to be introduced. These intelligent service robots are intended to support humans in everyday life. To achieve a most comfortable human-robot interaction with non-expert users it is, thus, imperative for the acceptance of such robots to provide interaction interfaces that we humans are accustomed to in comparison to human-human communication. Consequently, intuitive modalities like gestures or spontaneous speech are needed to teach the robot previously unknown objects and locations. Then, the robot can be entrusted with tasks like fetch-and-carry orders even without an extensive training of the user. In this context, this dissertation introduces the multimodal Object Attention System which offers a flexible integration of common interaction modalities in combination with state-of-the-art image and speech processing techniques from other research projects. To prove the feasibility of the approach the presented Object Attention System has successfully been integrated in different robotic hardware. In particular, the mobile robot BIRON and the anthropomorphic robot BARTHOC of the Applied Computer Science Group at Bielefeld University. Concluding, the aim of this work, to acquire a qualitative Scene Model by a modular component offering object attention mechanisms, has been successfully achieved as demonstrated on numerous occasions like reviews for the EU-integrated Project COGNIRON or demos

Modélisation et simulation 3D de la morphogenèse

The embryo of the Drosophila Melanogaster undergoes a series of cell movements during its early development. Gastrulation is the process describing the segregation of the future internal tissues into the interior of the developing embryo. Gastrulation starts with the formation of the ventral furrow, a process commonly known as the ventral furrow invagination. During this process, the most ventrally located blastoderm cells flatten and progressively constrict their apical sides until they are wedge shaped. As a result of these cell-shape changes, the blastoderm epithelium first forms an indentation, the ventral furrow, which is then completely internalized. We focus on the study of the mechanisms that drive the invagination. The main questions that gave birth to this thesis are: “What is the role of the apical constriction of the ventral cells in the invagination?” and “Once the ventral cells are internalized, what is the mechanism that drives the ventral closure?” We attempt to answer to these two questions from a biomechanical point of view. For this purpose, a 3D mesh of the embryo of the Drosophila Melanogaster has been created. Based on this mesh, two “a minima” biomechanical models of the Drosophila embryo have been created, a physically based discrete model and a model based on the Finite Element Method. The results of the simulations in both models show that the geometry of the embryo plays a crucial role in the internalization of the ventral cells. The two models efficiently simulate the internalization of the ventral cells but are incapable of reproducing the ventral closure. We hypothesize that the ventral closure can be explained by the interplay of forces developed in the embryo once the internalized ventral cells undergo cell division. We propose an approach to divide elements in a Finite Element Mesh and we integrate it to the Finite Element Model of the Drosophila Melanogaster.L'embryon de la Drosophila Melanogaster subit une série des mouvements cellulaires pendant son développement. La gastrulation est le processus qui décrit la différentiation des futurs tissus à l'intérieur de l'embryon. La gastrulation commence par la formation du sillon ventral, un processus connu sous le nom de “Ventral Furrow Invagination”. Pendant ce processus, les cellules de la blastoderme positionnées dans la région ventrale de l'embryon, aplatissent et contractent leur surface apicale jusqu'à ce qu'elles deviennent prismatiques. Ce changement de forme cellulaire aboutit à un enfoncement au niveau de la région ventrale, le sillon ventral, qui est ensuite totalement intériorisé. Nous focalisons notre étude sur les mécanismes qui conduisent à l'invagination. Les questions principales auxquelles ce travail de thèse essaie de répondre sont: “Quel est le rôle de la contraction apicale des cellules ventrales dans l'invagination?” et “Quel est le mécanisme qui conduit à la clôture ventrale, une fois les cellules ventrales intériorisées?”. Nous essayons de répondre à ces questions d'un point de vue biomécanique. Dans ce but, un maillage 3D de l'embryon de la Drosophila Melanogaster a été créé. Basés sur ce maillage, deux modèles biomécaniques “a minima” de l'embryon de la Drosophila ont été créés: un modèle physique discret et un modèle basé sur la Méthode des Eléments Finis. Les résultats des simulations des deux modèles montrent que la géométrie joue un rôle décisif dans l'intériorisation des cellules ventrales. Les deux modèles ont permis de simuler l'intériorisation des cellules ventrales mais se trouvent incapables de simuler la clôture ventrale. Notre hypothèse est que la clôture ventrale peut s'expliquer par l'intéraction des forces développées à l'intérieur de l'embryon, une fois que les cellules ventrales commencent à proliférer. Nous proposons une méthode pour diviser des éléments dans un maillage d'éléments finis et ensuite nous expliquons l'intégration de cette méthode dans le modèle des Eléments Finis pour l'embryon de la Drosophila Melanogaster

Dynamic Incentives for Optimal Control of Competitive Power Systems

This work presents a real-time dynamic pricing framework for future electricity markets. Deduced by first-principles analysis of physical, economic, and communication constraints within the power system, the proposed feedback control mechanism ensures both closed-loop system stability and economic efficiency at any given time. The resulting price signals are able to incentivize competitive market participants to eliminate spatio-temporal shortages in power supply quickly and purposively

Large scale dynamics of the atmosphere: Planetary waves

Planetary waves (PW) are global scale waves in the atmosphere, which are known to considerably impact weather patterns in the midlatitudes in the troposphere and the ozone distribution in the stratosphere. PW play an important role in coupling middle atmosphere dynamics. Due to the fact that climate change causes a decrease of the meridional temperature gradient, the strength of the zonal wind might decrease. This should, in turn, change the planetary wave activity (PWA). In order to quantify possible changes in the PWA we analyze ERA–Interim temperature data (10 m to 65 km height) on the Northern Hemisphere and calculate the so-called dynamical activity index (DAI) as measure for the PWA. We analyze the PWA to find indications for PWA changes and variability. We also use rotational temperature data from hydroxyl airglow measurements at UFS Schneefernerhaus (Germany) embedded in the international Network for the Detection of Mesospheric Change (NDMC) in the upper mesosphere/lower thermosphere (UMLT). We find an indication for a significant increase of the PWA in the stratosphere. The change of the PWA with higher zonal wavenumbers turns out to be strongest. This finding is in agreement with the expectation that a weakening of the meridional temperature gradient leads to improved vertical propagation conditions for planetary waves. With the empirical mode decomposition (EMD) we are able to extract non-stationary signals of the PWA time series. We further find that longer-term oscillations (QBO, ENSO and solar cycles) have a noticeable impact on the PW variability in all considered heights. Next to the 11-year cycle that is related to the sunspot-cycle in many studies, we also find a pronounced quasi-22-year signal. We tentatively interpret this signal as being due to the solar-magnetic-field (“Hale cycle”)

Science at the environmental research station Schneefernerhaus / Zugspitze

Das Buch enthält 22 Aufsätze, in denen die in der Forschungsstation Schneefernerhaus / Zugspitze aktiven Forscherinnen und Forscher ihre Arbeitsgebiete und bisherige Ergebnisse vorstellen. Die Aufsätze sind dabei so konzipiert, dass das Buch auch für die universitäre Lehre eingesetzt werden kann