WHY OVER-ROTATION IS NOT GOOD FOR ROTATIONAL SHOT PUT?

This study used three-dimensional motion analysis to determine the motion of rotational shot put. We sought to elucidate the effect of over-rotation in rotational shot put. The results showed that dirction of the center of gravity of the body (CG direction) correlates with the angular momentum of the shot-and-thrower system. As the magnitude of variability of CG direction relative to the horizontal plane increased, angular momentum of the shot-and-thrower system relative to its vertical axis decreased at the second turn @ < 0.05). CG direction showed a strong dependence on the contact position of the foot. We suggest that throwers avoid over-rotation by placing the foot straight from L-off to Lon

DEVELOPMENT OF SOFTWARE FOR ANALYZING STEP LENGTH COURSES IN SPRINT DASH WITH THE USE OF THE LASER VELOCITY MEASURING DEVICE AND DIGITAL VIDEO CAMERA

We have developed software (sprint-performance analyzer: SPA) for estimating step length courses in sprint dash with the use of the laser velocity measuring device and digital video camera. It gives a quick feedback to coaches and athletes and helps to evaluate performance of athletes. In this research, we compared time of analyzing by the SPA with that not utilizing the software. In addition, step length courses estimated in this measuring method were reexamined. A statistical analysis was done between estimated step length (ESL) by SPA and actual step length (ASL) by using Two-dimensional motion analysis method. Time of analyzing by SPA was 10 minutes/trial, which was shorter than 50 minutes/trial of that not utilizing the software. There were very small differences (?d) between the filtered ESL and the filtered ASL at respective trials (?d=0.00-0.04m)

KINEMATIC AND TECHNICAL FACTORS FOR ACCELERATION OF WHOLE BODY IN ROTATIONAL SHOT PUT TECHNIQUE

The aim of this study was to gain the knowledge about kinematic and technical parameters required for acceleration of whole body in rotational shot put technique, using three-dimensional motion analysis. 12 male shot putters participated this study. From the results, linear momentum during double support phase (DSP) (r = 0.64, 0.79, p \u3c 0.05, 0.01) and angular momentum during flight phase (FP) and 2nd single support phase (SSP2) (r = 0.58-0.72, p \u3c 0.05, 0.01) were closely related with throwing record, and these parameters would indicate the acceleration of whole body. In addition, path length of center of gravity at DSP related with linear momentum (r = 0.75, p \u3c 0.01). And the velocity of right toe, right elbow and left heel were closely related with angular momentum during FP and second single support phase (SSP2). These results can be concluded that enhancement these parametars will be effective techniques for acceleration of whole body

FEATURES OF INVULERSE PENDULUM MODEL USING HIGH-SPEED RUN-UP IN JAVELIN THROWING

This study uses three-dimensional motion analysis to determine features of the throwing motion in male javelin throwers. Run-up speeds were compared and features of the inverse pendulum model were determined using three-dimensional motion analysis. The results showed that run-up speed correlated with throwing distance. As run-up speed increased, the pendulum angle at L-on enlarged and tilted backwards (p < .01) after the width of the pendulum increased during the double-support phase. We presumed that the enlarged backward tilt converted a large amount of energy to increase the speed of run-up at L-on

Adsorption enhancement of nitrogen gas by atomically heterogeneous nanospace of boron nitride

In this study, porous boron nitride (p-BN) with hexagonal phase boron nitride (h-BN) pore walls was synthesized using high-temperature calcination. Negligible variation in pore-wall structure can be observed in powder X-ray diffraction (XRD) profiles and infrared (IR) spectra. However, a highly stable p-BN with a stable pore structure even at 973 K under the oxidative conditions is obtained when synthesized at higher than 1573 K under nitrogen gas flow. For p-BN, this stability is obtained by generating h-BN microcrystals. Nitrogen adsorption–desorption isotherms at 77 K provide type-IV features and typical adsorption–desorption hysteresis, which suggests micropore and mesopore formation. Moreover, adsorption–desorption isotherms of Ar at 87 K are measured and compared with those of nitrogen. The relative adsorbed amount of nitrogen (i.e., the amount of nitrogen normalized by that of Ar at each relative pressure or adsorption potential value) on p-BN is considerably larger than that on microporous carbon at low-pressure regions, which suggests the existence of strong adsorption sites on the p-BN surface. In fact, the relative number of adsorbed nitrogen molecules to that of Ar on p-BN is, at most, 150%–200% larger than that on microporous carbon for the same adsorption potential state. Furthermore, additional adsorption enhancement to nitrogen between P/P0 = 10−5 and 10−3 can be observed for p-BN treated at 1673 K, which suggests the uniformly adsorbed layer formation of nitrogen molecules in the vicinity of a basal planar surface. Thus, unlike typical nanoporous sp2 carbons, p-BN materials have the potential to enhance adsorption for certain gas species because of their unique surface state

New insights into the heat of adsorption of water, acetonitrile, and n-hexane in porous carbon with oxygen functional groups

Isosteric heat of adsorption is exquisitely sensitive to structural changes in carbon surfaces based on the energetic behavior of the interactions between adsorbates and carbon materials. We discuss the relationships between porous structures, oxygen functional groups, and heat of adsorption based on the behavior of the heat of adsorption of polar and non-polar fluids on porous carbon materials with oxygen functional groups. The porosity and functional groups of porous carbon materials were estimated from N2 adsorption isotherms at 77 K and temperature-programmed desorption. High-resolution adsorption isotherms of water, acetonitrile (polar fluid), and n-hexane (non-polar fluid) were measured on porous carbon materials with different pore size distributions and amounts of oxygen functional groups at various temperatures. The heats of adsorption were determined by applying the Clausius-Clapeyron equation to the adsorption isotherms. The heat of adsorption curves directly reflect the effects of interactions of fluid-oxygen functional groups,fluid-basal planes of pore walls, and fluid-fluid interfaces. In particular, the heat of adsorption curve of water is very sensitive to surface oxygen functional groups. This finding indicates the possibility of estimating the relative amounts of oxygen functional groups on porous carbon materials based on the amounts of water adsorbed at specific relative pressures

The ideal porous structure of EDLC carbon electrodes with extremely high capacitance

We propose an ideal porous structure of carbon electrodes for electric double-layer capacitors (EDLCs). The porous carbon successfully improved the gravimetric capacitance above ?200 F g?1 even in an organic electrolyte by utilizing the carbon nanopore surface more effectively. High-resolution transmission electron microscopy images and X-ray diffraction patterns classified 15 different porous carbon electrodes into slit-shape and worm-like-shape, and the pore size distributions of the carbons were carefully determined applying the grand canonical Monte Carlo method to N2 adsorption isotherms at 77 K. The ratio of pores where solvated ions and/or desolvated ions can penetrate also has a significant effect on the EDL capacitance as well as the pore shape. The detailed study on the effect of porous morphologies on the EDLC performance indicates that a hierarchical porous structure with a worm-like shaped surface and a pore size ranging from a solvated ion to a solvent molecule is an ideal electrode structure

Selective probe of the morphology and local vibrations at carbon nanoasperities

We introduce a way to selectively probe local vibration modes at nanostructured asperities such as tips of carbon nanohorns. Our observations benefit from signal amplification in surface-enhanced Raman scattering (SERS) at sites near a silver surface. We observe nanohorn tip vibration modes in the range 200-500 cm(-1), which are obscured in regular Raman spectra. Ab initio density functional calculations assign modes in this frequency range to local vibrations at the nanohorn cap resembling the radial breathing mode of fullerenes. Careful interpretation of our SERS spectra indicates presence of caps with 5 or 6 pentagons, which are chemically the most active sites. Changes in the peak intensities and frequencies with time indicate that exposure to laser irradiation may cause structural rearrangements at the cap.ArticleJOURNAL OF CHEMICAL PHYSICS. 136(6):064505 (2012)journal articl

Condensed Multiwalled Carbon Nanotubes as Super Fibers

The ultra-low intershell shear strength in carbon nanotubes (CNTs) has been the primary obstacle to applications of CNTs as mechanical reinforcements. In this paper we propose a new CNT-system composed of comprising of coaxial cylindrical shells of sp2-bonded carbons with condensed intershell spacings. Our atomistic calculations show that such condensed multiwalled carbon nanotubes (CMWNTs) can greatly enhance intershell shear strengths by several orders, and can simultaneously generate higher tensile strengths and moduli respectively than those of ordinary CNTs. It has further shown that CMWNTs can maintain thermally stable up to 2,000 K. By taking advantage of the primary enhancement mechanism of CMWNTs, a method of producing CMWNTs is therefore proposed tentatively. It is believed that CMWNTs featured with those properties can be taken as excellent candidates of super fibers for creating space elevators