1,053 research outputs found

    Phase Field Model for Dynamics of Sweeping Interface

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    Motivated by the drying pattern experiment by Yamazaki and Mizuguchi[J. Phys. Soc. Jpn. {\bf 69} (2000) 2387], we propose the dynamics of sweeping interface, in which material distributed over a region is swept by a moving interface. A model based on a phase field is constructed and results of numerical simulations are presented for one and two dimensions. Relevance of the present model to the drying experiment is discussed.Comment: 4 pages, 7 figure

    A THREE-DIMENSIONAL CINEMATOGRAPHIC ANALYSIS OF THE BASEBALL PITCH

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    Pitching is one of the most important aspects of the game of baseball. However, only a small number of quantitative biomechanical studies have been reported (Feltner & Dapena, 1986). Specifically, there have been few studies of the motion of the forearm and wrist joints during a pitching action. The purpose of this study is to record the changes in angles and angular velocities of the shoulder, elbow, radioulnar and wrist joints during a baseball pitch. In this study, three dimensional (3-D) high-speed cinematography was used to record the fastball pitches of varsity baseball pitchers

    A Three-Dimensional Cinematographic Analysis of Badminton Strokes

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    Badminton and tennis are two of the most popular striking activities, Broer & Zernicke (1979) stated that one evident difference between the two sports skills was the degree to which the wrist snap was used. They stated that the wrist snap just before impact was the most essential action of badminton strokes and it was enabled by the lightness of the badminton racket. Gowitzke & Waddell (1979) analyzed forehand and backhand smash strokes, representative of the most powerful overhead striking motions in badminton. They concluded that medial rotation of the humerus at the shoulder joint and pronation of the forearm at the radio-ulnar joints were the principal contributing movements for the forehand smash, In badminton strokes, many joint actions in three planes are involved in the striking motion, so that two-dimensional procedures are insufficient for analyzing the stroke motion of badminton. Relatively small numbers of biomechanical studies have been completed on kinematic parameters of badminton strokes. Quantitative studies with threedimensional procedures have been even more limited. The purpose of this investigation was to determine the changes of joint angles of the upper body during the execution of the drop shot and the cut shot in badminton using three dimensional cinematography

    MOMENT OF FORCE AND MECHANICAL POWER IN GIANT SWING ON THE HORIZONTAL BAR

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    Introduction In the giant swing backwards, frictional force acts upon the grip and air resistance acts upon the whole body (Hay, 1978; and Kreighbaum and Barthels, 1981). These resistive forces affect the rotation of the body and cause a loss of mechanical energy. Therefore in order to complete the rotation, the gymnast has to offset these energy losses using muscular work (Hay, 1978). It has been reported that changes in mechanical energy occur during the backward giant swing. The total energy of the body is decreased during the second half of the downswing and almost recovered in the first half of the upswing. These results suggest that muscular work is done in the first half of the upswing to offset the loss of mechanical energy in the last half of the downswing (Okamoto, Sakurai, Ikegami and Yabe)

    The Changes in Mechanical Energy During the Giant Swing Backward on the Horizontal Bar

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    In the giant swing backward, mechanical energy of the whole body is decreased due to friction between gymnast hands and the bar, and to air resistance. To complete the rotation, the gymnast has to do muscular work to offset these energy losses. Total mechanical energy changes with the relationship between energy loss and muscular work. Therefore, for biomechanical investigation of the giant swing backward, it is important to have an accurate measure of the mechanical energy changes of the whole body. Although there are many studies of energetics of the human fundamental movement such as walking and running, the mechanical energy changes of the whole body have not been reported during the giant swing backward on the horizontal bar. The purpose of this study is to report the mechanical energy changes of the whole body, and to identify the muscular work donc by the gymnast during the giant swing backward on the horizontal bar

    Primary Primitive Neuroectodermal Tumor of the Conus Medullaris in an Elderly Patient: A Case Report and Review of the Literature

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    Primary spinal primitive neuroectodermal tumors (PNETs) are very rare conditions. Most of these tumors occur in children and young adults. A 63-year-old man with a primary spinal PNET in the conus medullaris from the L1 to L2 level is presented in this report. The optimal treatment of primary spinal PNETs is yet unknown. Surgical resection, radiation therapy, and chemotherapy have been advocated for the treatment of spinal PNET based on PNETs at other sites. However, the outcome is very poor. There are a few reports of cases with long-term survival and no recurrence. In these patients, en bloc resections were performed

    An Artificial Intelligence Technique to Characterizae Surface-Breaking Cracks

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    A neural network with an analog output is presented to determine the angle of inclination of a surface-breaking crack from ultrasonic backscattering data. A neural network which was trained by the use of synthetic data set to estimate the depth of a crack, assuming that the inclined crack angle is known, was presented earlier[1,2]. In this study, a neural network estimates the angle of inclination of the surface-breaking crack, assuming that the depth of the crack is 2.0mm, by utilizing the waveforms of backscattered signals from the crack. The plate with a surface-breaking crack is immersed in water and the crack is insonified from the opposite side of the plate. The angle of incidence with the normal to the insonified face of the plate is taken to be 18.9°. The neural network is a feed-forward three layered network. The training algorithm is an error back-propagation algorithm which has been discussed in Refs. [3,4]. The theoretical data obtained by the boundary element method are used for the training. The performance of the trained network is tested by synthetic and experimental data

    SXDF-UDS-CANDELS-ALMA 1.5 arcmin2^2 deep survey

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    We have conducted 1.1 mm ALMA observations of a contiguous 105′′×50′′105'' \times 50'' or 1.5 arcmin2^2 window in the SXDF-UDS-CANDELS. We achieved a 5σ\sigma sensitivity of 0.28 mJy, providing a flat sensus of dusty star-forming galaxies with LIR∼6×1011L_{\rm IR} \sim6\times10^{11} L⊙L_\odot (for TdustT_{\rm dust} =40K) up to z∼10z\sim10 thanks to the negative K-correction at this wavelength. We detected 5 brightest sources (S/N>>6) and 18 low-significance sources (5>>S/N>>4; these may contain spurious detections, though). One of the 5 brightest ALMA sources (S1.1mm=0.84±0.09S_{\rm 1.1mm} = 0.84 \pm 0.09 mJy) is extremely faint in the WFC3 and VLT/HAWK-I images, demonstrating that a contiguous ALMA imaging survey is able to uncover a faint dust-obscured population that is invisible in deep optical/near-infrared surveys. We found a possible [CII]-line emitter at z=5.955z=5.955 or a low-zz CO emitting galaxy within the field, which may allow us to constrain the [CII] and/or the CO luminosity functions across the history of the universe.Comment: 4 pages, 2 figures, 1 table, to appear in the proceedings of IAU Symposium 319 "Galaxies at High Redshift and Their Evolution over Cosmic Time", eds. S. Kaviraj & H. Ferguso
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