Transmission of motion     

Joseph Harrison 《Journal of The Franklin Institute》1872,94(4):233-243

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Section of physics and chemistry: A meeting of the section was held in the Hall of the Institute on thursday evening,November 15, 1917, at 8 o'clock,with Prof. Alexander E. Outerbridge,Jr., in the chair. The minutes of the previous meeting were read and approved     

Joseph S. Hepburn 《Journal of The Franklin Institute》1917,184(6):912

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A vacuum tube amplifier for small direct voltages     

Joseph Razek 《Journal of The Franklin Institute》1935,219(2):137-155

A simple means for combining a small direct voltage with an alternating carrier is described. This consists of connecting the direct voltage in series with an alternating voltage of the same order of magnitude. The two are then passed through a copper oxide rectifier which suppresses one part of the cycle. The degree of suppression depends upon the magnitude of the direct voltage. The resulting fluctuating voltage can be amplified to any desired degree in a conventional amplifier.The theory for the simple case of pure resistance is worked out, with an example. The solution of the more general case with inductances is indicated.The practical circuit which has been used for the amplification of thermo-couple currents, and as a galvanometer power multiplier, is shown.  相似文献   

Leonardo Da Vinci,The Anatomist, 1452–1519: By J. Playfair McMurrich Professor of Anatomy University of Toronto. Carnegie Institution of Washington Publication No. 411. Williams & Wilkins Company,Baltimore, Copyright 1930, xx — 265 pages,price $6.oo     

Joseph S. Hepburn 《Journal of The Franklin Institute》1931,211(3):393-394

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The role of upper torso and pelvis rotation in driving performance during the golf swing   总被引：3，自引：2，他引：1  

Myers J  Lephart S  Tsai YS  Sell T  Smoliga J  Jolly J 《Journal of sports sciences》2008,26(2):181-188

While the role of the upper torso and pelvis in driving performance is anecdotally appreciated by golf instructors, their actual biomechanical role is unclear. The aims of this study were to describe upper torso and pelvis rotation and velocity during the golf swing and determine their role in ball velocity. One hundred recreational golfers underwent a biomechanical golf swing analysis using their own driver. Upper torso and pelvic rotation and velocity, and torso-pelvic separation and velocity, were measured for each swing. Ball velocity was assessed with a golf launch monitor. Group differences (groups based on ball velocity) and moderate relationships (r > or = 0.50; P < 0.001) were observed between an increase in ball velocity and the following variables: increased torso-pelvic separation at the top of the swing, maximum torso-pelvic separation, maximum upper torso rotation velocity, upper torso rotational velocity at lead arm parallel and last 40 ms before impact, maximum torso-pelvic separation velocity and torso-pelvic separation velocity at both lead arm parallel and at the last 40 ms before impact. Torso-pelvic separation contributes to greater upper torso rotation velocity and torso-pelvic separation velocity during the downswing, ultimately contributing to greater ball velocity. Golf instructors can consider increasing ball velocity by maximizing separation between the upper torso and pelvis at the top of and initiation of the downswing.  相似文献   

Coordination variability and skill development in expert triple jumpers   总被引：1，自引：0，他引：1  

Wilson C  Simpson SE  van Emmerik RE  Hamill J 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(1):2-9

The aim of this study was to examine the influence of skill of expert triple jumpers on the coordination variability of lower extremity intra-limb couplings. In contrast to the traditional motor learning perspective, we hypothesized that as skill and thus performance increases, movement coordination variability will also increase. Three-dimensional kinematic and ground reaction force data were collected during the hop-step transition phase of the triple jump. Relative motion plots and a modified vector coding technique were used to quantify the coordination variability across the trials. The results were consistent with a U-shaped curve, representing coordination variability, as skill increases. The high coordination variability in less skilled athletes is present while the appropriate characteristics defining the movement coordination patterns are acquired. This coordination variability may not be beneficial to performance. As the refinement of these characteristics is achieved, coordination variability decreases, resulting in a more consistent or regulated performance. In the final stages of developing a skilled performance, a functional variability is accessed that brings flexibility to the system allowing it to cope with perturbations. This study highlights the need to address the learning effect when analysing coordination variability from a dynamical systems perspective.  相似文献   

Concluding remarks by the president of the conference     

Joseph A. Lauwerys 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1965,11(4):479-484

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Some educational problems of children from immigrant,refugee and migrant families in U.S.A.     

Joseph S. Roucek 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1962,8(2):225-235

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Book reviews     

Richard Meister  W. D. Wall  Fritz Bohnsack  B. F. Nel  Helmut Meyer-Bothling  Joseph S. Roucek  F. W. Prins  Hans Möckelmann  H. J. Dallmer 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1961,7(1):112-127

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Records of research     

Joseph Gray Jackson 《Journal of The Franklin Institute》1952

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