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931.
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935.
Vicente J. Beltrán-Carrillo José Devís-Devís Carmen Peiró-Velert 《Sport, Education and Society》2018,23(3):257-269
Drawing on semi-structured interviews with older adolescents, this article examines how healthism, ideal body discourses and performative body discourses influence their (non)participation in physical activity (PA) and their identity construction concerning exercise, sport and physical education. We illustrate that body transformation through PA, and related slim body desire and the fear of masculinised female bodies, affect adolescents’ decisions to engage in or drop out of sport. Also, a non-hegemonic body shape combined with a display of low physical competence triggers classmate and teachers’ rejection and marginalisation, affecting adolescents’ construction of embodied identities and preventing them from being active. Finally, adolescents who are competent in sport are less influenced by ideal body discourses than by performative body discourses. We highlight the health promotion effects of these hegemonic discourses and suggest strategies to challenge them. 相似文献
936.
研究了复合材料叠层板的初始缺陷和拉伸-弯曲耦合对于其振动、屈曲和非线性动力稳定性的影响,推导了控制方程,这是一个修正的非线性Mathieu方程,进行了5种典型复合材料的数值计算,它们是玻璃环氧Scotch-1002,芳纶环氧Kevlar-49,硼环氧B4/5505,石墨环氧T300/5208和AS/3501,结果表明,由于初始缺陷以及耦合效应的存在,使叠层板对于进入参数共振更加敏感,并且其振幅大于无初始缺陷或者无耦合效应的叠层板,对于不同材料的复合叠层板,尤其是层数较少的板,耦合效应是不相同的,在板结构的屈曲和动力稳定性设计中,如果忽略了耦合效应的影响,其不安全性将超过10%以上。 相似文献
937.
Pak Kin Wong Xiang Hui Gao Ka In Wong Chi Man Vong 《Journal of The Franklin Institute》2018,355(4):1517-1538
Modern engines are controlled by electronic control units, which operate all the engine actuators based on the signals from various sensors in the engine. Traditionally, the control parameters of the actuators are obtained through huge amount of trial-and-error experiments. However, using traditional approach to calibrate these parameters becomes more challenging with the increasing incorporation of new technologies into advanced engines. In order to reduce the number of experiments required in the calibration process of modern engines, a novel point-by-point engine calibration approach based on machine learning methods is proposed in this study. It is an iterative procedure that, for a given operating point, sequential design of experiment (DoE) strategy is utilized to measure the responses of different engine sensors corresponding to different actuator signals, and a machine learning algorithm called initial-training-free online extreme learning machine is utilized to incrementally learn the relationship between the sensors and actuators based on the measurement acquired. In each iterative cycle, meta-heuristic optimization is performed on the machine-learning-based model to search for the best parameters, which are then used as the initial parameters for generating DoE plan of the next cycle. The iteration is repeated until the optimal parameters of that operating point are found. To verify the effectiveness of the proposed approach, experiments on both simulation engine in commercial software and real engine in test bench have been conducted. The results show that the engine calibration can be carried out with significant fewer experiments and time by using the proposed approach. 相似文献
938.
Ulrich Thiel André Everts Barbara Lutes und Kostas Tzeras 《Informatik - Forschung und Entwicklung》1998,13(3):147-158
Zusammenfassung. In diesem Beitrag wird eine „digitale Bibliothek” definiert als informationelle Umgebung, in der in integrierter Form verteilte
Informationsquellen zug?nglich sind. Die Suche ist normalerweise ein interaktiver Proze?, in dem verfügbare Informationen
in unterschiedlichen Formaten und in unterschiedlichen Kontexten benutzt werden. Ein wichtiges Forschungsthema im Bereich
digitaler Bibliotheken ist daher der Entwurf anwendungsspezifischer Methoden für den Zugang zu heterogenen Wissensquellen,
die sich bzgl. Thema, Format, Verfügbarkeit, Qualit?t und vieler anderer Eigenschaften stark unterscheiden k?nnen. Um dieser
Anforderung gerecht zu werden, müssen die eingesetzten Information-Retrieval-Systeme eine sehr pr?zise Suche erm?glichen.
Dabei reicht es nicht aus, lediglich Dokumente und Daten nachzuweisen, vielmehr müssen die gefundenen Informationen im Kontext
des Informationsbedarfs des Benutzers eingebunden sein. Für diese Aufgabe schlagen wir Retrieval-Methoden vor, die auf abduktiver
Logik basieren.
Eingegangen am 19. Januar 1998 / Angenommen am 28. Juli 1998 相似文献
939.
We propose and describe Parameterized filesystem HITS (PFH), a lightweight rearrangement algorithm that performs a re-ranking of existing content-only search results in tree-like
hierarchical corpora, such as a filesystem. PFH does this by combining the content analysis of the results with structural
analysis of how they are organized. An α parameter is used to vary the structure-content bias, allowing us to observe changes
in performance when we place more emphasis on structure or on content. Using real and simulated data, experiments are provided
to show that α = 0.8 (i.e, 20% structure and 80% content) can substantially boost Mean Reciprocal Rank while keeping other
IR metrics steady. Such an algorithm may be useful for building retrieval systems over hierarchical content such as Desktop
Search, technical documents and books. 相似文献
940.
Ben Piggott Sean Müller Paola Chivers Carmen Papaluca Gerard Hoyne 《European Journal of Sport Science》2019,19(3):267-286
Sports science research is traditionally monodisciplinary despite calls for an interdisciplinary focus. The primary purpose of this systematic review was to identify studies on talent identification, talent selection and competition performance to determine whether interdisciplinary research is being conducted. Thirty-six studies met the selection criteria. These studies were critiqued relative to sport, skill level, sport science sub-disciplines included, and whether the research was multidisciplinary or interdisciplinary. The secondary purpose of the review was to critique the level of analysis and level of representative task design in performance tests used in the studies. Twenty-five studies were categorised as interdisciplinary, with 11 categorised as multidisciplinary. Thirteen sports were represented with soccer the most frequent followed by field hockey, Australian Rules football, handball and rugby league. Thirty-two studies completed their analysis at a group level and four at an individual level. A total of 337 performance tests were rated for representative task design with 64 categorised as low, 123 as medium and 150 as high. The results pertaining to interdisciplinary studies and individual analyses are discussed in relation to constraints theory, which predicts that interacting variables can explain sport performance. Sports science research is beginning to fulfil the call for interdisciplinary research. Future research, however, needs to consider individual analyses and representative task design of tests to progress sports science knowledge. 相似文献