Motomu Nakashima

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This paper reviews unsteady flow conditions in human swimming and identifies the limitations and future potential of the current methods of analysing unsteady flow. The capability of computational fluid dynamics (CFD) has been extended from approaches assuming steady-state conditions to consideration of unsteady/transient conditions associated with the body(More)
This study aims to clarify the mechanism of generating unsteady hydrodynamic forces acting on a hand during swimming in order to directly measure the forces, pressure distribution, and flow field around the hand by using a robotic arm and particle image velocimetry (PIV). The robotic arm consisted of the trunk, shoulder, upper arm, forearm, and hand, and it(More)
This study aims to clarify the mechanisms by which unsteady hydrodynamic forces act on the hand of a swimmer during a crawl stroke. Measurements were performed for a hand attached to a robotic arm with five degrees of freedom independently controlled by a computer. The computer was programmed so the hand and arm mimicked a human performing the stroke. We(More)
The primary objective of this study was to develop a robot for research of human swimming. In order to address this objective, we developed the upper body of an underwater humanoid robot and realized the human swimming stroke. The developed humanoid robot had the same body proportions and appearance at half the size of a real human. The upper limbs were(More)
Performance-based features of the recent first European Standard for seismic design of buildings (EN1998-1:2004) and of the final draft European Standard for seismic assessment and retrofitting of buildings (prEN1998-3, May 2004) are reviewed, with emphasis on concrete buildings. EN1998-1:2004 includes two performance levels: (a) local collapse endangering(More)
The aim of this paper is to study the bending properties of tail flukes of a dolphin. The bending test was carried out to obtain the displacements on different test points of a fluke. The Young’s moduli of the ligamentous layer and the dense connective tissue in the flukes were obtained from the tensile test and the compression test. In order to establish(More)
The control of balance is a primary objective in most human movements. In many cases, research or practice, it is essential to quantitatively know how good the balance is at a body posture or at every moment during a task. In this paper we suggest a new measure for postural upright stability which assigns a value to a body state based on the probability of(More)
This research addresses the question: what is the risk of fall initiation at a certain human posture? There are postures from which no one is able to keep their balance and a fall will surely initiate (risk=1), and others from which everyone may regain their stability (risk=0). In other postures, only a portion of people can control their stability. One may(More)