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Andrej Milec 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1969,15(3):352
Ohne Zusammenfassung 相似文献
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Kokot G Vilfan M Osterman N Vilfan A Kavčič B Poberaj I Babič D 《Biomicrofluidics》2011,5(3):34103-341039
We observed and measured the fluid flow that was generated by an artificial cilium. The cilium was composed of superparamagnetic microspheres, in which magnetic dipole moments were induced by an external magnetic field. The interaction between the dipole moments resulted in formation of long chains-cilia, and the same external magnetic field was also used to drive the cilia in a periodic manner. Asymmetric periodic motion of the cilium resulted in generation of fluid flow and net pumping of the surrounding fluid. The flow and pumping performance were closely monitored by introducing small fluorescent tracer particles into the system. By detecting their motion, the fluid flow around an individual cilium was mapped and the flow velocities measured. We confirm that symmetric periodic beating of one cilium results in vortical motion only, whereas asymmetry is required for additional translational motion. We determine the effect of asymmetry on the pumping performance of a cilium, verify the theoretically predicted optimal pumping conditions, and determine the fluid behaviour around a linear array of three neighbouring cilia. In this case, the contributions of neighbouring cilia enhance the maximal flow velocity compared with a single cilium and contribute to a more uniform translational flow above the surface. 相似文献
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The estimation of the economic effects of cultural events is a topic that has stirred numerous debates in cultural economics. Although economic impact studies and contingent valuation have been the most frequently used methods, both suffer from numerous problems. In this article, we use ex-post econometric verification as a new and promising method in cultural economics in the estimation of the economic effects of cultural events and apply it to the estimation of the effects of the 2012 European Capital of Culture Maribor on tourism and employment. This enables us to compare results from economic impact and ex-post econometric verification studies to find significant differences in particular in terms of new employment. We determine the net effects on new tourism and find that they were mainly present in Maribor, the holder of the project, and not in the other five partner cities. We conclude by reflecting on the state of the art of the studies of economic effects of cultural events in cultural economics and their relevance for the study of cultural tourism. 相似文献
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The quality of production (e.g. paper, typesetting, reproduction of illustrations, printing and bookbinding) of a book (reprint) is very important. The quality of a 1978 reprint of a book from 1921 was studied using standard and non-destructive testing methods such as microscopic and spectroscopic techniques. Chemical, physical and colorimetric properties of the papers, colour differences of the prints and typographic tonal density were analysed. Results showed that the reprint is not an identical copy of the original. Some of the differences in the reprint compared with the original (e.g. typographic tonal density) could easily have been avoided while others (e.g. structural and optical properties of paper, colour prints) are unavoidable, mainly because of the influence of internal and external factors on ageing. Ageing influences the properties of paper and colour print: optical and colour properties deteriorate and colour fades. It is concluded that precise and systematic evaluation of the properties of an old book should be carried out before a reprint is prepared. The results of the research, using non-destructive methods such as microscopy, spectroscopy and image analysis, are useful for characterising the properties of paper and printing ink, typography and reproduction of illustrations. 相似文献
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This paper examines several different approaches to exploiting structural information in semi-structured document categorization. The methods under consideration are designed for categorization of documents consisting of a collection of fields, or arbitrary tree-structured documents that can be adequately modeled with such a flat structure. The approaches range from trivial modifications of text modeling to more elaborate schemes, specifically tailored to structured documents. We combine these methods with three different text classification algorithms and evaluate their performance on four standard datasets containing different types of semi-structured documents. The best results were obtained with stacking, an approach in which predictions based on different structural components are combined by a meta classifier. A further improvement of this method is achieved by including the flat text model in the final prediction. 相似文献
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Andrej Vidak Senad Odžak Vanes Mešić 《Research in Science & Technological Education》2019,37(3):324-345
Background: It is widely known that for many students it is very difficult to correctly predict how thermal expansion affects the appearance of a metal plate with a circular hole. Interviews with school teachers show that the source of this difficulty could stem from the fact that students’ internal visualizations of an arbitrary object’s thermal expansion often boil down to visualizing changes along one dimension only.
Purpose: In this study, we investigated how students’ mental models about one-dimensional expansion can be extended for purposes of running mental simulations about expansion along two dimensions.
Sample: To that end a pretest-posttest quasi-experiment has been conducted, with 100 students in the control group and 95 students in the experimental group.
Design and methods: Whereas control group students received traditional instruction with a focus on formal representations, in the experimental group the students were led to draw an analogy between heating of a straight rod and a circular rod of same length, whereby the internal structure of the rods was represented by springs.
Results: Eventually, it has been found that students from the experimental group were significantly more successful at predicting the effects of thermal expansion, especially within contexts of objects with holes.
Conclusion: Analogies and extreme case reasoning can be effectively used for helping the students to correctly transfer their mental models about one-dimensional expansion to situations that require reasoning about expansion along two dimensions. 相似文献