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1.
John Bruzzo A. L. Schwab Antti Valkeapää Aki Mikkola Olli Ohtonen Vesa Linnamo 《Sports Engineering》2016,19(2):91-104
The role of simulation models in sport disciplines has become relevant lately due to the multiple advantages that they may offer sports teams, coaches and practitioners. This paper develops and presents a simple three-dimensional multibody dynamic model of a cross-country skier, modeling a single propulsion phase to obtain the kinetic parameters involved in the movement. A professional Olympic-level skier performed the skating technique without poles in a ski tunnel under controlled conditions and on an incline plane. Then, with a force acquisition system attached to the ski bindings and a motion capture system set on site, the leg resultant forces and the movement of specific points of the skier’s lower body were acquired. The data obtained from the motion capture system were used as the prescribed kinematic input data in the multibody model and the measured force was used later as a parameter of comparison with the results of the simple model. After simulating the technique, the calculated resultant forces seem to be in agreement with those measured in the field. 相似文献
2.
We employed the grounded theory method to construct a framework describing the distinctive mechanisms through which big-science centers generate industrial knowledge spillovers in the economy. Our focus is on large-scale big-science installations typically associated with experimental physics. We draw on social network, social capital, and inter-organizational learning theories to examine knowledge spillovers accruing to industrial partner companies in big-science-industry dyads. The context for the study is provided by CERN’s new particle accelerator project, the Large Hadron Collider (LHC). In addition to building a grounded theory framework for the study of industrial knowledge spillovers, our study demonstrates the distinctive potential that big-science centers offer as a source of knowledge spillovers in national innovation systems. 相似文献
3.
Esa Puukilainen Olli Ohtonen Teemu Lemmettylä Vesa Linnamo Björn Hemming Toni Laurila Salla Tapio Markku Räsänen Mikko Ritala Markku Leskelä 《Sports Engineering》2013,16(4):229-238
In this work, changes in the cross-country ski base properties resulting from stone grinding, skiing, waxing and re-stone grinding have been investigated. The surface topography, crystallinity, wettability and sliding properties of cross-country ski bases were recorded using a selection of measurement techniques: non-contact chromatic confocal microscopy, contact-type surface roughness analyser and scanning electron microscopy (topography), Raman spectroscopy (crystallinity), contact angle measurement (wettability) and a ski tester (sliding properties). The tested skis were used for 150 km and waxed 35 times. The ski base surface became smoother and the orientation and crystallisation of the base material increased. Wear decreased the hydrophobicity and increased the sliding friction. Even though re-grinding did not restore all of the ski base properties, re-grinding improved the wettability and sliding properties. The results help to optimise stone grinding interval to maintain the performance of the skis. 相似文献
4.
Olli Ohtonen Stefan Lindinger Teemu Lemmettylä Seppo Seppälä Vesa Linnamo 《Sports Engineering》2013,16(4):281-296
The aim of the present study was to design, construct and scientifically validate a two-dimensional force measurement binding system for cross-country skiing. The system consists of two force measurement bindings. One binding was designed for analysing classic skiing (vertical and anterior–posterior [along the ski] force components) and the other one for skate (freestyle) skiing (vertical and medio-lateral [transverse to the ski] force components). Validation was accomplished using a three-step process: (1) accuracy tests for the sensors in two temperatures, (2) sport-specific imitation jump test on standard force plates in a laboratory and (3) comparing the system against force measurement reference systems that are currently used when skiing on snow. During sport-specific imitation jumps, differences in peak forces and impulses between the classic binding and the reference systems ranged from 8.0 to 19.9 % and were two to three times greater compared to differences between the skate binding and the reference systems (range ?5.9 to 5.5 %). However, high similarity coefficients were observed with both bindings (classic binding 0.990–0.996, skate binding 0.996–0.999) compared to the reference systems. Based on these results, the skate binding was shown to be fully valid for use in field measurements of skate skiing, whereas some improvements have to be performed in the construction and sensor placements for the classic binding (vertical as well as anterior–posterior force component). 相似文献
5.
Jarkko Mylläri Heikki Kynäslahti Olli Vesterinen Sanna Vahtivuori-Hänninen Lasse Lipponen Seppo Tella 《Scandinavian Journal of Educational Research》2013,57(5):537-550
This article discusses students' pedagogical thinking in situations where the use of information and communication technologies (ICTs) has a (well-defined) pedagogical role and rationale. By analysing students' pedagogical thinking in this setting, it is also possible to better understand their motivations and self-regulation. Pedagogical thinking as viewed from the student's angle is a new area of educational research. Our research method is a combination of the Stimulated Recall interview and the semi-structured theme interview. In addition, some background data were gathered by questionnaire to discern students' different uses of ICTs and their contexts. The findings suggest how the educational use of ICTs is considered to be meaningful and motivating by both genders and among all the interviewed age groups, in spite of the fact that an acute and vocal critique seems to develop among older students. The differences reside in students' reasoning regarding decision making in task operations between genders, which was one of the background variables—girls actively include identity and opinion, while boys emphasize the quality of performance as motives for decisions. 相似文献
6.
Taina Huurre Päivi Santalahti Olli Kiviruusu Tytti Solantaus 《Scandinavian Journal of Educational Research》2013,57(6):656-673
The study investigated whether cuts to school resources made during economic recession contribute to children's psychiatric and economic problems in early adulthood. The cohort consisted of 817 Finnish children. Data was gathered from teachers during a recession (child age 12) and from national registers on children's post-recession use of psychiatric and income benefit services (age 18–28). Children's need for remedial instruction, special education, or psychosocial services was associated with later use of income support and psychiatric services. Those receiving special education had an increased risk for adulthood use of psychiatric services as compared to those who needed, but did not receive, this service. A decrease in material resources and teachers' loss of motivation predicted children's later use of psychiatric services. 相似文献
7.
Olli Rissanen Tuire Palonen Petteri Pitkänen Gustav Kuhn Kai Hakkarainen 《Vocations and Learning》2013,6(3):347-365
The purpose of the present study was to examine expertise in magic by interviewing 16 prominent Finnish magicians who were identified earlier through a social network analysis of 120 Finnish magicians. A semi-structured interview was administered that addressed the participants’ histories; their relationship to magic, the nature of their expertise, the networked development of expertise, their engagement with magical expertise and their motivation for cultivating such expertise. The results indicated that expertise in magic is cultivated, to a great extent, by informal networks of expertise without formal training. The participants had become excited about magic as children and started to pursue an expertise in the field from a relatively early age (4 to 14 years). In accordance with other domains of expertise, it had taken about 10 years of cultivating skills and competencies before becoming professional in the field, with a few exceptions. Ego-centric network analyses revealed that there were three or four magicians who had significantly shaped the Finnish field of magic and affected most of the participants’ development and career. Most of the participants were clustered, forming a core of Finnish magicians, and those magicians working abroad and collaborating with international magicians were located at the periphery of the Finnish network or formed an isolated network of clusters within it. 相似文献
8.
This paper examines the exploitation of inertial measurements to analyze javelin throwing mechanics. The main objective was to demonstrate that consumer-grade inertial navigation systems, augmented with some position and attitude data obtained from a video sequence, yield detailed information of the mechanics of javelin throwing. Especially, such a system makes it possible to analyze the momentary force and power exerted on the javelin during the acceleration phase. Although the presented system is a pilot, leaving space for further improvements, it already reveals the potential of inertial navigation systems to sports. In practise, an inertial measurement unit was embedded inside the tip of the javelin to determine the javelin’s momentary attitude, position, and velocity. Graphs on the speed and angular velocity about the longitudinal axis of the javelin during the whole performance are presented. The maximum estimated release speed and release angular speed were 28.02 m/s and 215.9 rad/s, respectively. The acceleration phase trajectory of the javelin and its deviation from a straight line path are demonstrated. Additionally, the momentary forces and powers are shown and the effect of aerodynamic forces on the projectile is specified. The magnitude of the maximum tangential forces and accelerating powers were 364 N and 9.76 kW. The duration and length of the acceleration phase trajectory varied between 223 and 231 ms, and 2.48 and 2.75 m. To estimate the accuracy of the inertial measurements, the acceleration phase results were compared to measurements made with high-speed cameras. 相似文献
9.
Xingguo?ZhouEmail authorView author&#;s OrcID profile Johanna?Kallo Risto?Rinne Olli?Suominen 《Educational Assessment, Evaluation and Accountability》2018,30(3):313-342
This article examines the reforms of basic education inspection in China since 1977, which is accomplished by drawing from a historical institutionalism approach. The empirical analysis is based on policy documents and laws and is supplemented with interview materials. Throughout this work, we have identified three distinct periods: the restoration stage from 1977 until the 1990s, the formalization stage from the 1990s until 2007, and the transition stage from 2007 onwards. The changes of education inspections indicate there is a perceptible path dependency, especially in the change from the first stage to the second one, where the expansion of education inspections was to consolidate the selected path by enhancing its jurisdictive power and promoting its disposition in the educational system. Reforming these inspections to some extent proves the historical stance of “positive feedback” as coined by Pierson (2004) for the growing stage of an organization, but in fact, the expansion of the system appears also to be significantly more problematic or complex than a linear development that is based on positive feedback. From the transition stage, interaction with global players is increasing, with implications for the development of the school inspection system. The finding shows that by 2015, the collaboration with global players influenced the development of Jiance system—a large-scale assessment of students’ academic achievement at grade four and eight—which the inspection sector managed to incorporate into itself. The article argues that this decision to extend the spectrum of education inspection to assessment practices reflects the aspiration of the inspection authorities to reinforce the capacities to survive and thrive in the changing local and global environments of educational quality assurance and evaluation. 相似文献
10.
Recent research emphasizes the context‐specific nature of professional knowledge and expertise, implying that developing novel practices in authentic environments is a prerequisite for teachers' professional development. The aim of this study was to find out how teachers develop their practical knowledge and expertise through shared planning and to evaluate an innovative learning project carried out in an ICT‐based environment. Two secondary school teachers of history participated in this study. The data were gathered using a multi‐methodological approach (video recordings, interviews and questionnaires). The results are described in terms of the teachers' shared experiences and their increased awareness of their own scaffolding practices. Discussion is focused on the role of boundary crossing in teachers' negotiation of new meanings.
La recherche récente souligne le caractère contextualisé de la connaissance et de la compétence professionnelles. De ce fait un environnement authentique est exigé pour rendre possible le progrès des pratiques nouvelles et ainsi le développement professionnel de l'enseignant. L'objet de cette étude est de définir les moyens par lesquels les enseignants développent une connaissance et une compétence pratiques à travers une préparation et une évaluation partagées pendant un projet d'apprentissage innovant réalisé dans un environnement basé sur les technologies de l'information et de la communication. Deux enseignants d'histoire d'un collège ont participé à cette recherche. Les données ont été recueillies selon une approche faisant intervenir plusieurs méthodes (enregistrements de vidéo, interviews, questionnaires). Les résultats sont décrits dans l'optique des expériences partagées des enseignants et de leur prise de conscience progressive de leurs propres pratiques fondamentales de tous les jours. La discussion est concentrée sur le rôle de pluridisciplinarité dans la négociation de sens nouveaux par les enseignants.
Los estudios recientes subrayan la naturaleza específica al contexto del conocimiento y de la pericia profesional. Esto implica que el desarrollo de nuevas prácticas en entornos auténticos es un prerrequisito para el desarrollo profesional de los profesores. La meta de este trabajo es de descubrir como los profesores desarrollan su conocimiento y pericia profesional através del planeamiento y de la evaluación de un proyecto innovativo efectuado en un entorno de aprendizaje ICT. Dos profesores de escuela secundaria con historia laboral participaron en este estudio. La información fue recogida utilizando métodos múltiples (grabaciones en video, entrevistas, cuestionarios). Los resultados están descritos en términos de las experiencias compartidas de los profesores y el incremento del conocimiento de sus propias prácticas de andamiaje. La discusión se enfoca en la cuestión del papel del cruce de límites en la negociación de nuevos significados de la enseñanza.
In der gegenwärtigen Forschung wird die kontextspezifische Natur des Fachwissens und der beruflichen Expertise betont. Dies impliziert, dass die Entwicklung von neuen Verfahrensweisen in authentischen Umgebungen eine Voraussetzung für die berufliche Weiterbildung von Lehrern darstellt. Das Ziel des vorliegenden Artikels besteht darin, herauszuarbeiten, wie Lehrer ihr unterrichtspraktisches Wissen und ihre Berufsexpertise durch solche kooperativen Planungs‐ und Evaluationsvorgänge erweitern können, die in einer IKT‐basierten Umgebung ausgeführt werden. Zwei Geschichtslehrer der Sekundarstufe I (secondary school) haben sich an dieser Untersuchung beteiligt. Die Datenerhebungen basieren auf einer methodisch vielfältigen Anlage: Video‐Aufzeichnungen, Interviews und Fragebögen. Die Ergebnisse werden in bezug auf die Erfahrungen der Lehrer, sowie deren gesteigerte Wahrnehmung der jeweils eigenen zugrundeliegenden Lehrverfahren beschrieben. Die Diskussion fokussiert auf einen Aspekt, der die Rolle der Grenzüberschreitung im Zusammenhang mit unterrichtlichen Verhandlungen über neue Bedeutungen betrifft. 相似文献