Static and dynamic accuracy of a magnetic-inertial measurement unit used to provide racket swing kinematics     

Benjamin Kane Williams  Ross H. Sanders  Joong Hyun Ryu  Pitre C. Bourdon  Philip Graham-Smith  Peter J. Sinclair 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(2):202-214

Magnetic-inertial measurement units (MIMUs) are becoming more prevalent in sports biomechanics and may be a viable tool to evaluate kinematic parameters. This study examined the accuracy of a MIMU to estimate orientation angles under static conditions and dynamically from a squash racket during a forehand drive shot. A MIMU was mounted onto a goniometer and moved through 0–90°, with static data collected at 10° increments during 10 repetitions of all three axes. Typical error analyses showed the MIMU to be very reliable (TE ≤ 0.03°). MIMU accuracy was determined via intraclass correlation coefficients (ICC) (r > 0.999, p < 0.001). An ordinary least products regression showed no proportional bias and minimal fixed bias for all axes. Dynamic accuracy was assessed by comparing MIMU and optical motion capture data of squash racket swing kinematics. A MIMU was fixed onto a racket and 10 participants each hit 10 forehand shots. Mean orientation angle error at ball impact was <0.50° and ICC showed very high correlations (r ≥ 0.988, p < 0.001) for all orientations. Swing phase root mean squared errors were ≤2.20°. These results indicate that a MIMU could be used to accurately and reliably estimate selected racket swing kinematics.  相似文献   

Some new derivatives of diacetyl     

Harry F. Keller  Philip Maas 《Journal of The Franklin Institute》1897,144(5):379-385

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Disburdened valves     

Philip Mayer 《Journal of The Franklin Institute》1870,90(6):361-364

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A note on the measurement of small time intervals     

Philip P. Quayle 《Journal of The Franklin Institute》1927,203(3):407-412

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Notes on theory and practice of evaporation     

Philip B. Sadtler 《Journal of The Franklin Institute》1908,166(5):395-401

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Statistics in the service of comparative education     

Idenburg  Philip J. 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1965,11(4):434-452

International Review of Education - A realistic consideration of the part that statistics can play in the study of comparative education must regard as the first desiderata the development of...  相似文献   

Frequency-coordinate vector diagram     

Philip F. Ordung  Herbert L. Krauss 《Journal of The Franklin Institute》1951,251(3):343-350

From the standpoint of circuit synthesis as well as for a fundamental comprehension of circuit behavior, it is desirable to be able to visualize the response of a circuit over an extended frequency range by means of a geometrical construction. Mathematically, the response of a circuit can be expressed with the La Place transform theory as a function of the complex frequency variable, p = α + jωw, in which a is the decrement and ω is the “real” angular frequency. Physically, the nature of the real-frequency response is usually not discernible by casual inspection of the mathematical function. This paper develops a means of visualizing this frequency response readily through the construction of a vector diagram from the response function.  相似文献   

Analysis of faulted power systems, : Paul M. Anderson. 513 pages,diagrams, 7 × 10 in. Iowa State University Press,Ames, Iowa, 1973. Price, $20.00 (approx. £9·95).     

Philip C. Magnusson 《Journal of The Franklin Institute》1974,298(1):79

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Caple's seven laws of luck     

Philip Seyer 《Performance Improvement》1988,27(9):20-20

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Within‐High‐School Versus Across‐High‐School Scaling of Admissions Assessments: Implications for Validity and Diversity Effects          下载免费PDF全文

Jack W. Kostal  Paul R. Sackett  Nathan R. Kuncel  Philip T. Walmsley  Melissa S. Stemig 《Educational Measurement》2017,36(1):39-46

Previous research has established that SAT scores and high school grade point average (HSGPA) differ in their predictive power and in the size of mean differences across racial/ethnic groups. However, the SAT is scaled nationally across all test takers while HSGPA is scaled locally within a school. In this study, the researchers propose that this difference in how SAT scores and HSGPA are scaled partially explains differences in validity and subgroup differences. Using a large data set consisting of 170,390 students each of whom matriculated at one of 114 separate colleges, the researchers find that awarding SAT scores by ranking SAT within a high school generally results in substantial reduction in the size of subgroup mean differences for this predictor. However, validity for predicting first‐year GPA is also reduced by a small amount. Conversely, placing HSGPA onto a nationally normed metric through the use of multiple regression procedures results in a moderate increase in the size of subgroup mean differences, while also producing a small increase in validity. Taken together, these findings suggest that differences in predictor scaling can partially explain differences in the size of subgroup mean differences between HSGPA and SAT scores and have implications for predictive power.  相似文献