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Starting block performance in swimming is of crucial importance in the individual competitions for the shorter swimming distances as well as for the relay events. The significance of this swim start performance will increase with the introduction of a new starting block with a longer and slightly steeper surface in conjunction with a push-off support for the feet and laterally adjustable handles. As grab starts and track starts were equally observed in international swimming competitions there are good reasons to assume that only the latter will remain the dominant starting technique. This report aims to summarize existing knowledge on the biomechanics of the swim start performed on a traditional starting block as a new starting block is introduced and new starting techniques are going to be developed. Following some introductory remarks on the assessment of the swim start performance, results will be discussed on the merit of different take-off techniques, on the entry behaviour, and on the force development profiles on the starting block. In conclusion, a tendency in favour of the rear-weighted track start was found in conjunction with a flat entry. In addition, it could be shown that an angular momentum around the transverse body axis combined with a dolphin kick (and a previously hyperextended hip joint) may provide hydrodynamic conditions to enter the water with a rather steep centre of mass trajectory. Finally, existing biomechanical knowledge will be presented on the relay start as well as on a possible change in the starting technique using the new block. 相似文献
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Dirk Siebert Patrick Neumann Armin Schulz Gabriele Faulkner und Thomas Tolxdorff 《Informatik - Forschung und Entwicklung》2001,16(2):93-102
Zusammenfassung. Für ein vollst?ndig computergestütztes Planungssystem zum Zwecke der kieferchirurgischen Operationsplanung ist die Bereitstellung
von virtuellen Werkzeugen für den Chirurgen eine grundlegende Voraussetzung. Ausgehend von den Volumendaten mit Sch?del- und
Kieferknochen des Patienten erm?glicht ein einfaches Interface unter Verwendung einer geeigneten Visualisierung und haptischer
Eingabeger?te die interaktive Definition und Manipulation einzelner virtueller Knochensegmente. Wir haben moderne kraftrückgekoppelte
Ger?te aus dem Niedrigpreisbereich eingebunden und auf ihre F?higkeit untersucht, das dreidimensionale Verst?ndnis im Planungsproze?durch
Anlehnung an die Vorg?nge bei der chirurgischen Prozedur zu erh?hen. Durch diese Eingabeger?te ist es m?glich, die Knochensegmentierung
für eine Osteotomie des Unterkiefers intuitiver und schneller durchzuführen. Die definierten Teilvolumina ergeben zusammen
mit ihrer r?umlichen Neuanordnung auf Grundlage einer kephalometrischen Analyse einen Operationsplan. Nach erfolgter Planung
werden die Planungsergebnisse in den Operationssaal übertragen. Die intraoperativen Techniken beinhalten die Visualisierung
der Planungsergebnisse, die Steuerung der Anwendung über Sprache und die Bestimmung der Patientenposition mittels eines elektromagnetischen
3D-Trackingsystems.
Eingegangen am 27. April 2000 / Angenommen am 21. Februar 2001 相似文献
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The purpose of this study was to examine the effects of a short-term time management training programme on perceived control of time and perceived stress. The sample of 177 freshmen was randomly assigned to a time management training (n?=?89) and an active control group (CG) (n?=?88). We expected that an increase in external demands during the first weeks of the semester would lead to more perceived stress in the CG, but not in the time management training group, due to the time management intervention. As hypothesised, perceived stress increased in the CG, but not in the time management training group. Furthermore, perceived control of time increased in the time management training group but remained unchanged in the CG. Even a rather short intervention of 2?h can protect freshmen from an increase in perceived stress at the beginning of the semester. 相似文献
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Armin Hust 《Informatik - Forschung und Entwicklung》2005,19(4):224-238
Information Retrieval Systeme haben in den letzten Jahren nur geringe Verbesserungen in der Retrieval Performance erzielt.
Wir arbeiten an neuen Ans?tzen, dem sogenannten Collaborativen Information Retrieval (CIR), die das Potential haben, starke
Verbesserungen zu erreichen. CIR ist die Methode, mit der durch Ausnutzen von Informationen aus früheren Anfragen die Retrieval
Peformance für die aktuelle Anfrage verbessert wird. Wir haben ein eingeschr?nktes Szenario, in dem nur alte Anfragen und
dazu relevante Antwortdokumente zur Verfügung stehen. Neue Ans?tze für Methoden der Query Expansion führen unter diesen Bedingungen
zu Verbesserungen der Retrieval Performance .
The accuracy of ad-hoc document retrieval systems has reached a stable plateau in the last few years. We are working on so-called
collaborative information retrieval (CIR) systems which have the potential to overcome the current limits. We define CIR as
a task, where an information retrieval (IR) system uses information gathered from previous search processes from one or several
users to improve retrieval performance for the current user searching for information. We focus on a restricted setting in
CIR in which only old queries and correct answer documents to these queries are available for improving a new query. For this
restricted setting we propose new approaches for query expansion procedures. We show how CIR methods can improve overall IR
performance.
CR Subject Classification H.3.3 相似文献
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Because hedonic aspects of products are difficult to evaluate prior to consumption, consumers seek signals to reduce their uncertainty. Opinion leaders, such as critics, may serve as key informants to consumers. This study considers the different roles and incentives of literary critics and how they influence the success of books. Furthermore, it empirically investigates the impact of 4 book critics featured on Germany's most popular literary television show, Das Literarische Quartett, on reviewed books' success. The variety of control variables included in the mixed regression models provide results pertaining to not only the critics, but also the success factors of books in general. Book success does not depend primarily on the mere appearance of a book on a television show or a favorable review of it; rather, awareness and word-of-mouth effects seem crucial, and books are more likely to succeed if critics disagree about the quality and express extreme judgments, even if those judgments are negative. 相似文献
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Armin Beverungen conducts research on how universities retain their charitable status in a market environment, and on the teaching of ethics in business schools. Steffen Böhm has a particular interest in the economics and management of sustainability. He has also founded an open access journal and an open access press, MayFlyBooks. Christopher Land works on artists and the management of their creativity. 相似文献
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Ton de Jong Armin Weinberger Isabelle Girault Anders Kluge Ard W. Lazonder Margus Pedaste Sten Ludvigsen Muriel Ney Barbara Wasson Astrid Wichmann Caspar Geraedts Adam Giemza Tasos Hovardas Rachel Julien Wouter R. van Joolingen Anne Lejeune Constantinos C. Manoli Yuri Matteman Tago Sarapuu Alex Verkade Vibeke Vold Zacharias C. Zacharia 《Educational technology research and development : ETR & D》2012,60(5):883-901
Science Created by You (SCY) learning environments are computer-based environments in which students learn about science topics in the context of addressing a socio-scientific problem. Along their way to a solution for this problem students produce many types of intermediate products or learning objects. SCY learning environments center the entire learning process around creating, sharing, discussing, and re-using these learning objects. This instructional approach requires dedicated instructional designs, which are supplied in the form of what are called pedagogical scenarios. A SCY pedagogical scenario presents the learning process as an organized assembly of elementary learning processes, each associated with a specific learning object and a tool for creating this learning object. Designing a SCY learning environment is basically a two-step procedure: the first step is to select one of the available scenarios, and the second step is to define the domain content. The SCY technical infrastructure then handles the instantiation of the scenario as a SCY computer-based learning environment. In this article we describe the SCY pedagogical design scenarios and report on our experiences in designing four different SCY learning environments. 相似文献