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981.
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J Witters G Heremans W Bohets V Stijnen H Van Coppenolle 《Journal of sports sciences》1985,3(3):197-206
The basic principles underlying the design of a velocimeter based on an unwinding wire, for use in athletics research, are discussed. It is shown by theoretical analysis that, in order to avoid runaway effects, the tension on the wire should be either high or low but not of intermediate strength. The low tension regime is shown to be theoretically the most favourable as it combines high accuracy of speed measurements in decelerated motion with insensitivity to resonance oscillations of the wire. Practical considerations concerning the ruggedness of the apparatus, however, favour the high tension regime. A modern apparatus incorporating microprocessors and working with thin nylon wire stretched by a force of the order of 1 N, i.e. in the high tension regime, has been constructed and tested. The test results show that the velocity of decelerated motions (up to decelerations of the order of 10 m s-2) can be faithfully recorded in the velocity range 0-15 m s-1. The relative error for the measurement of constant speed up to 15 m s-1 is about one in a thousand, which is very small and practically unattainable by other methods. An application to the study of the long jump is demonstrated and validated by the use of film analysis. 相似文献
985.
986.
In 1990, the American College of Obstetricians and Gynecologists (ACOG) became the first national organization to receive a model phase Integrated Academic Information Management System (IAIMS) grant from the National Library of Medicine. The goal of the ACOG model phase project is to develop and test a prototype for an integrated system that will meet the needs of ACOG and NAACOG members in patient care, research, education, and administrative information. The model phase goal will be accomplished primarily through ACOGQUEST, an integrated approach to providing accurate, current, quality-filtered information to ACOG and NAACOG members in a variety of formats. Another method of information dissemination now being tested is a heuristic-based patient management database, which will include a concise, interactive display of ACOG-reviewed information that can be incorporated into patient records. 相似文献
987.
988.
Wout Van Den Bor 《International Journal of Educational Development》1985,5(3):167-181
Discussions of the problems of expatriate educational research with and in developing countries are at the core of this paper. How should a research project be set up? Who should initiate it and finance it? How does it fit into an overall development strategy? These and other questions are analysed sensitively and with understanding. The paper also examines how research questions should be formulated and how the research should be designed. Inevitably there are hidden objectives which do not appear explicit in the early stages. There are yet others which should be made explicit. Problems also arise over collecting and disseminating data, especially when the time comes to publish a report. So often political and other considerations influence the final report. Ultimately, however, the success or failure and the value or otherwise of any research depends on an intricate web of relationships, at the heart of which must be mutual trust. 相似文献
989.
Forty boys and girls of two age groups (mean ages 52 and 70 months, respectively) performed 35 trials on a throwing task demanding accuracy. As might be expected, the older children were significantly more accurate than the younger ones but there were no sex differences. Film analysis of the throws showed that, although both age groups attempted to employ the adult strategy of varying velocity while keeping ball-release angle constant, the younger group was less successful in the latter aspect. The manner in which consistent release angles were arrived at by the older group was through the use of a movement pattern in which the elbow angle did not change during the forward swing. Such a movement pattern appeared less frequently in the younger age group. The results of this study provide support for a mode of research identifying functionally relevant kinematic variables that can subsequently be shown to follow from distinctive execution categories. In such a way, changes in outcome measures with increasing age and/or skill level can be functionally understood and identified. 相似文献
990.
Museum objects are often highly complex and composed of materials with varying properties, some of which may have changed as a result of ageing and/or conservation treatments. Research into defining sustainable environmental conditions by balancing energy cost and risk to these vulnerable objects has mainly focused on experiments in laboratories with new, single materials or on computer modelling, but only to a limited extent on actual objects. This paper presents a method to collect empirical data from a large group of decorated wooden panels in order to investigate the effects of humidity fluctuations on these objects and relate them to their material properties and construction. Wooden panels were chosen as they are regarded to be particularly sensitive to fluctuations in relative humidity. The fluctuations may cause the wood to shrink and swell and can result in open glue joints, cracks, and deformation of the panels as well as losses and cracks in the decorative layers. Empirical data are scarcely available as yet but are essential to study relationships between material properties, type of construction, damage, and as input and validation for modelling and experimental studies. The method, referred to as the Rijksmuseum Study, was performed on a group of 300 objects from the furniture and paintings collections of the Rijksmuseum. 相似文献