On-line path planning with optimal C-space discretization

This paper is based on a path planning approach we reported earlier for industrial robot arms with 6 degrees of freedom in an on-line given 3D environment. It has on-line capabilities by searching in an implicit and descrete configuration space and detecting collisions in the Cartesian workspace by distance computation based on the given CAD model. Here, we present different methods for specifying the C-space discretization. Besides the usual uniform and heuristic discretization, we investigate two versions of an optimal discretization for an user-predefined Cartesian resolution. The different methods are experimentally evaluated. Additionally, we provide a set of 3- dimensional benchmark problems for a fair comparison of path planner. For each benchmark, the run-times of our planner are between only 3 and 100 seconds on a Pentium PC with 133 MHz

On-line path planning by heuristic hierarchical search

In this paper, the problem of path planning for robot manipulators with six degrees of freedom in an on-line provided three-dimensional environment is investigated. As a basic approach, the best-first algorithm is used to search in the implicit descrete configuration space. Collisions are detected in the Cartesian workspace by hierarchical distance computation based on the given CAD model. The basic approach is extended by three simple mechanisms and results in a heuristic hierarchical search. This is done by adjusting the stepsize of the search to the distance between the robot and the obstacles. As a first step, we show encouraging experimental results with two degrees of freedom for five typical benchmark problems

Social Determinants of Cognitive Functioning and Its Development in Old Age: The Role of Education, Spousal Loss and Neighborhoods in a Longitudinal Perspective

Populations are aging in many countries all over the world. This trend is not only manifest in increased numbers and population shares of older adults; it is also associated with increases in old-age life expectancy. In conjunction with the quantitative gain in years, questions about the quality of life have been expressed. This is reflected in Rowe & Kahn’s concept of Successful Aging, which posits that cognitive functioning (CF) is one of the main resources for active engagement with life in old age. Besides medical, biological and behavioral factors, social factors can be expected to play an important role in CF because they are often enduring or intense in nature and shape cognitively relevant experiences in many areas of life. Against this background, this dissertation examines potential social determinants of older adults’ CF. At the theoretical level, I combine a sociological perspective emphasizing the importance of social factors in shaping individual experiences throughout the life course with psychological theories that link individual experiences (e.g., mental stimulation, stress, physical activity) to CF. At the empirical level, I apply growth curve modeling, fixed effect regression, and multilevel analysis to data from the Longitudinal Aging Study Amsterdam to address the following research questions: Are more (vs. less) educated persons more likely to maintain their CF as they grow older? Will the loss of the spouse accelerate cognitive decline? Does the CF of people in better-off or urban neighborhoods differ from that of their counterparts in less well-off or rural neighborhoods? The results indicate that the social factors examined in this dissertation are hardly associated with cognitive decline in old age. However, cross-sectional comparisons of the level of CF by education and neighborhood characteristics reveal that being more educated and living in a more urbanized neighborhood are associated with higher CF

Accompanying “in-service teaching” internships of prospective mathematics teachers – a model for encouraging exchange between theory and practice using the triple coaching approach

Developing professional expertise of prospective teachers not only in terms of theoretical knowledge but also in terms of competencies of designing challenging and cognitively activating learning opportunities in the mathematics classroom is certainly one of the key aims of internship phases in pre-service mathematics teacher training. As mathematics-related theoretical contents of teacher training and practice-related learning opportunities of school internships are not always linked in an optimal way, this paper aims at discussing a model of an intensive internship phase combined with a triple coaching approach partly integrated in a course accompanying the internship phase

Ein allgemeiner Ansatz zur Montage deformierbarer linearer Werkstücke mit Industrierobotern

Diese Arbeit skizziert einen allgemeinen Ansatz zur Montage deformierbarer linearer Werkstücke (wie Kabel, Drähte, Schläuche, Blattfedern) mit Industrierobotern. Hierzu werden insbesondere die folgenden zwei Aspekte betrachtetet. Erstens die zuverlässige Ausführung der Montage unter Berücksichtigung der Werkstückdeformation und anderer Unsicherheiten, zweitens die numerische Simulation des Werkstückverhaltens. Zur robusten Ausführung der Montage wird das aus der Montage starrer Werkstücke bekannte Konzept der Manipulation-Skills auf deformierbare Werkstücke übertragen. Bei der numerischen Simulation wird insbesondere die Bestimmung der Greifertrajektorie bei gegebener Aufgabenstellung betrachtet

Aleksandr Bloks Drama Pesnja sud'by "Das Lied des Schicksals"

In der vorliegenden Arbeit wird versucht, eine möglichst erschöpfende Darstellung des Ideengehalts des LS ("Das Lied des Schicksals") zu geben und allen Verästelungen von Bloks esoterischer Mystik und anspielungsreicher Symbolik nachzugehen. Es zeigt sich, daß das LS zeitlich und thematisch einen besonders geeigneten Zugang zum Gesamtwerk Bloks ermöglicht

Aleksandr Bloks Drama Pesnja sud'by "Das Lied des Schicksals"

In der vorliegenden Arbeit wird versucht, eine möglichst erschöpfende Darstellung des Ideengehalts des LS ("Das Lied des Schicksals") zu geben und allen Verästelungen von Bloks esoterischer Mystik und anspielungsreicher Symbolik nachzugehen. Es zeigt sich, daß das LS zeitlich und thematisch einen besonders geeigneten Zugang zum Gesamtwerk Bloks ermöglicht