Student evaluations of teaching: brought to you by computer     

Joseph S. Fulda 《British journal of educational technology : journal of the Council for Educational Technology》2000,31(1):81-82

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A static method for obtaining a calibration factor for SRM bicycle power cranks   总被引：1，自引：0，他引：1  

Andrea L. Wooles  Anthony J. Robinson  Peter S. Keen 《Sports Engineering》2005,8(3):137-144

Many scientists and coaches are interested in mechanical power produced during cycling, and use Schoberer Rad Me\technik (SRM) bicycle power cranks to obtain this data. However, it has been expensive and difficult to calibrate SRM cranks, causing much of the collected data to be unreliable. We present a static method, derived from first principles, for obtaining a calibration factor for SRM cranks. A known mass and lever arm (chainring of a known diameter) are used to apply a known torque load to the instrument in four positions, and the output frequencies are used to calculate the calibration factor in Hz/Nm. The reproducibility of this method is ±0.01 Hz/Nm, which is acceptable for the application of the instrument, which is measurement of mechanical power application by cyclists at the crank. The method is reliable, inexpensive, and easy to set up, and will allow higher confidence in data collected using SRM power cranks. We recommend calibration of the power meter once every six months because of the measured drift of the calibration factor over time.  相似文献   

Editorial     

John S Edwards 《知识管理研究与实践》2006,4(4):259-260

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Editorial     

S. Mahadevan 《Resonance》2006,11(8):1-2

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Distribution of relative attention deficits on the WISC-R by age, sex, social class, and region     

M K Clampit  S J Silver 《Journal of learning disabilities》1989,22(4):258-259

We examined the demographic distribution of 102 subjects with attention deficits in the Wechsler Intelligence Scale for Children-Revised (WISC-R) (Wechsler, 1974) standardization sample. Neither age nor occupational status was significant; males were overrepresented (3:1); and the West was overrepresented by 50%, largely due to the relatively high proportion of females in the West who appeared within the attention deficit sample (41% in West vs. 19% in the rest of the nation). Replication is encouraged.  相似文献   

A comic author’s marketing techniques     

S. S. Hanna 《Publishing Research Quarterly》1990,6(2):37-43

What happens when an author undertakes a supplementary marketing campaign to university librarians? S. S. Hanna, the author of a comic account of finding a publisher, added to the efforts of the Iowa State University Press some communications of his own. The details of his campaign, and some of its results, are offered.  相似文献   

Abuse and neglect of children brought up in families with an alcoholic father in Bulgaria     

C Christozov  S Toteva 《Child abuse & neglect》1989,13(1):153-155

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Illustrations of electric displacement currents     

Joseph S. Ames 《Journal of The Franklin Institute》1923,195(6):787-798

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This is biology: The science of the living world     

S Mahadevan 《Resonance》2005,10(7):87-88

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Comparison of methods for determining power generated on a rope-braked cycle ergometer during low-intensity exercise     

K. L. Franklin  R. S. Gordon  J. S. Baker  B. Davies 《Sports Engineering》2006,9(1):29-38

This study compares the instrumentation and analysis techniques used when determining the power expended pedalling a rope-braked ergometer manufactured by Monark (Sweden) during a low intensity test. Power values were generated by eight subjects. The instrumentation consisted of load cells to measure the rope brake forces, a tachometer to measure the flywheel velocity and instrumented pedal cranks manufactured by Schoberer Rad Messtechnik (SRM). The subjects pedalled a rope-braked ergometer at 60 rev min^-1, against a resistance of 3 kg, for 5 minutes. Three different measurements of the mean power were recorded and these were compared with the value given by Monark. The SRM cranks provided two sets of results using different software packages supplied with the cranks. SRM standard software is used for taking measurements during training and cycle races over long time periods. An additional piece of software is provided by SRM called Ptnew, which gives readings of torque and pedal cadence over periods up to 30 seconds. Using the values supplied by Monark each subject generated 180 W of power. The mean power for the eight subjects, measured using the SRM cranks, was 170.36 W (SD 4.11) using the alternative SRM software (Ptnew) over a 30 second period and 173.68 W (SD 2.21) using the standard SRM software. From the direct measurement of the brake forces and flywheel velocity the mean power across the eight subjects was 148.90 W (SD 5.89). The SRM cranks measure the input power, whereas the direct measurement system measures the power output excluding mechanical losses. These values give a figure for the mechanical efficiency for the roped-braked ergometer of 88%. It was found that Monark overestimates the power generated by the subjects when compared with both the SRM systems and the direct measurement instrumentation.  相似文献