Disparitäten der Bildungsbeteiligung und des Kompetenzerwerbs

Zusammenfassung Herkunftsbedingte Unterschiede der Bildungsbeteiligung und des Kompetenzerwerbs stellen einen Untersuchungsschwerpunkt in der Pisa-Studie dar. In der Bundesrepublik war ein besonders enger Zusammenhang zwischen Strukturmerkmalen famili?rer Lebensverh?ltnisse (sozio?konomischer Status, Bildungsniveau, Migrationstatus), Bildungsbeteiligung und Kompetenzerwerb nachweisbar. Ziel des Beitrags ist es, auf Grundlage der Daten der nationalen Erweiterung von PISA die disparit?tserzeugenden Effekte famili?rer Strukturmerkmale durch Prozessmerkmale famili?rer Lebensverh?ltnisse (kulturelle und kommunikative Praxis), institutionelle (Schulform) und psychologische Faktoren zu erkl?ren. Dies geschieht in zwei Schritten: Zun?chst wird mit Hilfe von Strukturgleichungsmodellen gezeigt, dass die Effekte von famili?ren Strukturmerkmalen überwiegend durch die kulturelle Praxis von Familien vermittelt sind. In einer sequentiellen Berechnung von Regressionsmodellen ergeben sich sodann deutliche Hinweise darauf, dass die Wirkung famili?rer Struktur- und Prozessmerkmale im Wesentlichen über individuelle F?higkeits- und Motivationsunterschiede (kognitive Grundf?higkeiten, Lesegeschwindigkeit, Leseinteresse, metakognitive Lernstrategien) transportiert werden. Die psychologischen und institutionellen Vermittlungsmechanismen tragen gemeinsam, aber auch jeweils spezifisch und damit kumulativ zu sozialen Unterschieden im Kompetenzerwerb bei.

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Summary Disparities in Educational Participation and Attainment: An Institutional and Individual Mediation Model The effect of students’ social background on their educational participation and attainment is a central focus of the PISA study. For Germany, the link between structural features of the family background (socio-economic status, level of education, migration status) and educational participation and attainment was shown to be particularly strong. Drawing on data from the German national extension of the PISA study, an explanation of these disparity effects is proposed, relying on process-based features (cultural and communicative practices), institutional factors (school type) and psychological factors. This is done in a two-step approach. First, structural equation models are used to show that most effects of family background structures are mediated by families’ cultural practices. Second, sequential analyses of regression models are run, providing strong evidence to suggest that the effects of family structures and processes are essentially transmitted through individual differences in competencies and motivation (basic cognitive abilities, reading speed, interest in reading, meta-cognitive learning strategies). Psychological and institutional mediation mechanisms contribute, jointly as well as individually, and thus cumulatively, to social differences in attainment.

     

Stichwort: Literalität — Schriftlichkeit

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Three-dimensional nonlinear flutter analysis of long-span suspension bridges during erection

In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three-dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic forces caused by large deformation are fully considered. An interesting result obtained was that the bridge was more stable when the stiffening girders were erected in a non-symmetrical manner as opposed to the traditional symmetrical erection schedule. It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear factors should be considered accurately in aerodynamic stability analysis of long-span suspension bridges during erection. Project supported by National Natural Science Foundation of China(No. 598954410), and China Postdoctoral Science Foundation (No. 2002031245)     

Analysis and design of DSP-based dual-loop controlled UPS inverters

This paper presents a novel digital dual-loop control scheme of the PWM (Pulse with modulate) inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and control timing strategy is used to improve the system dynamic response. Simulation and experimental results presented in the paper verified the validity of the proposed control scheme.     

Indirect estimation of cable tension during gymnastic movements on rings

Knowledge of external forces acting on an athlete is often required to study performance and injury mechanisms, but direct measurements are difficult to obtain. While transducers in the rings cables typically measure external forces experienced by gymnasts performing static balances and swinging movements on rings, this solution is not always acceptable and an accurate technique that does not hinder the gymnasts’ performances is desirable. This study evaluates a video-based technique for estimating cable tension on the rings apparatus. Static loading of a rings frame coupled with a planar video analysis of the mandatory damped elastic devices (DEDs) provided a tension-deflection calibration curve. Three-dimensional video and cable tension data were obtained for two male gymnasts performing static balances and dynamic swinging movements. Cable tension was measured using a force link while a planar video analysis determined time histories of the DED deflections. Combined cable tension time histories were estimated fromrelative DED deflections coupled with the tension-deflection calibration curve and the orientation of the rings cables, and were compared to measured values to evaluate the proposed technique. For static balances the RMS difference between measured and estimated combined cable tension was 83 N. For dynamic swinging movements the maximum RMS difference was 189 N, equivalent to a 4% difference when expressed as a percentage of the peak value. The indirect video-based technique developed in this study accurately estimates combined cable tension throughout movements on rings and may be considered for studies where a remote measurement is required. There is potential for the technique to be extended to other sporting situations, where indirect accurate estimates of external forces acting on an athlete are needed.     

Comparison of numerical and analytical solutions for fly casting dynamics

This paper presents an approximate analytical model of the dynamics of a tapered fly line during a standard overhead cast. During casting, the line forms a nonlinear propagating wave that is frequently referred to as a ‘loop’ by fly casters. The geometry of the loop is described by three distinct parts: a straight bottom segment (attached to a stationary fly rod), a semi-circular segment that is propagating (i.e. the loop), and a straight top segment that is also propagating, (i.e. the traveling line). A fly (particle) is attached at the end of the traveling line. A work-energy balance yields the velocity of the fly as a function of the length of the traveling line. For a uniform fly line (level line), a closed-form solution is found, while for a tapered fly line, the solution is obtained by quadrature. A critical loop diameter arises in the analysis, and it determines whether the final velocity of the fly is greater or lesser than the initial velocity of the traveling line. The analytical solutions are critically compared against numerical solutions of a general model for fly line dynamics that relaxes many of the assumptions employed in the analytical model. The agreement between the two solutions remains close during the loop propagation phase, provided a significant amount of fly line remains in the traveling line. However, as the traveling line vanishes and the loop ‘turns over’, the two solutions diverge abruptly due to the many simplifying assumptions employed in the analytical model.     

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