scholarly journals Assessment of the accuracy of different systems for measuring football velocity and spin rate in the field

2019 ◽  
Vol 233 (2) ◽  
pp. 324-330 ◽  
Author(s):  
Katrine Okholm Kryger ◽  
Séan Mitchell ◽  
Steph Forrester
Keyword(s):  
Systematic Error ◽  
Confidence Intervals ◽  
High Speed ◽  
Football Player ◽  
Random Errors ◽  
High Speed Video ◽  
Field Assessment ◽  
Wide Range ◽  
Ball Velocity ◽  
Level Of Agreement

The aim of this study was to measure the level of agreement of four portable football velocity and spin rate measurement systems (Jugs speed radar gun, 2-D high-speed video, TrackMan and adidas miCoach football) against a Vicon motion analysis system. One skilled male university football player performed 70 shots covering a wide range of ball velocities (12–30 m s−1) and spin rates (94–743 r/min). A Bland–Altman analysis was used to assess the level of agreement. For ball velocity, the 2-D high-speed video had the smallest systematic error, followed by the radar gun, TrackMan and miCoach football at 0.2, 0.4, 0.5 and 4.8 m s−1, respectively. A similar ranking was also observed for the random errors (95% confidence intervals: ±0.4, ±1.5, ±1.9 and ±6.0 m s−1). The first three systems all tracked ball velocity in >90% of shots, while the miCoach football tracked slightly fewer shots (79%). For spin rate, the miCoach football had a much smaller systematic error (4 vs 38 r/min) and random error (95% confidence intervals: ±24 vs ±355 r/min) compared to TrackMan. The miCoach also successfully tracked spin rate in more shots than the TrackMan (79% vs 44%). These results indicate that 2-D high-speed video would be the preferred option for the field assessment of ball velocity; however, radar gun and TrackMan may also be appropriate. A minimum of 10 frames of 2-D high-speed video, captured close to the ball starting position, was demonstrated to be sufficient in providing a reliable measure of ball velocity. The miCoach ball is the preferred option for field assessment of ball spin rate.

scholarly journals Standard of the Initial Ball Velocity for a Fly Ball in Baseball Hitting

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 137
Author(s):  
Hirotaka Nakashima ◽  
Gen Horiuchi ◽  
Shinji Sakurai
Keyword(s):  
Initial Velocity ◽  
High Speed ◽  
Baseball Players ◽  
Ball Impact ◽  
Video Cameras ◽  
High Speed Video ◽  
Before And After ◽  
Ball Velocity ◽  
Opposite Field ◽  
Measuring Tape

This study aimed to determine the minimum required initial velocity to hit a fly ball toward the same field (left-field for right-handed batters), center field, and opposite field (right field for right-handed batters). Six baseball players hit fastballs launched by a pitching machine. The movements of the balls before and after bat-to-ball impact were recorded using two high-speed video cameras. The flight distance was determined using a measuring tape. Seventy-nine trials were analyzed, and the minimum required initial velocities of batted balls were quantified to hit balls 60, 70, 80, 90, 100, 110, and 120 m in each direction through regression analysis. As a result, to hit a ball 120 m, initial velocities of 43.0, 43.9, and 46.0 m/s were required for the same field, center field, and opposite field, respectively. The result provides a useful index for batters to hit a fly ball in each of the directions.

scholarly journals Agreement Between Spatiotemporal Gait Parameters Measured by a Markerless Motion Capture System and Two Reference Systems—a Treadmill-Based Photoelectric Cell and High-Speed Video Analyses: Comparative Study (Preprint)

2020 ◽  
Author(s):  
Felipe García-Pinillos ◽  
Diego Jaén-Carrillo ◽  
Victor Soto Hermoso ◽  
Pedro Latorre Román ◽  
Pedro Delgado ◽  
...  
Keyword(s):  
Video Analysis ◽  
Contact Time ◽  
High Speed ◽  
Step Length ◽  
Flight Time ◽  
Reference Systems ◽  
Random Errors ◽  
Step Frequency ◽  
Temporal Parameters ◽  
High Speed Video

BACKGROUND Markerless systems to capture body motion require no markers to be attached to the body, thereby improving clinical feasibility and testing time. However, the lack of markers might affect the accuracy of measurements. OBJECTIVE This study aimed to determine the absolute reliability and concurrent validity of the Kinect system with MotionMetrix software for spatiotemporal variables during running at a comfortable velocity, by comparing data between the combination system and two widely used systems—OptoGait and high-speed video analysis at 1000 Hz. METHODS In total, 25 runners followed a running protocol on a treadmill at a speed of 12 km/h. The Kinect+MotionMetrix combination measured spatiotemporal parameters during running (ie, contact time, flight time, step frequency, and step length), which were compared to those obtained from two reference systems. RESULTS Regardless of the system, flight time had the highest coefficients of variation (OptoGait: 16.4%; video analysis: 17.3%; Kinect+MotionMetrix: 23.2%). The rest of the coefficients of variation reported were lower than 8.1%. Correlation analysis showed very high correlations (<i>r</i>&gt;0.8; <i>P</i>&lt;.001) and almost perfect associations (intraclass correlation coefficient&gt;0.81) between systems for all the spatiotemporal parameters except contact time, which had lower values. Bland-Altman plots revealed smaller systematic biases and random errors for step frequency and step length and larger systematic biases and random errors for temporal parameters with the Kinect+MotionMetrix system as compared to OptoGait (difference: contact time +3.0%, flight time −7.9%) and high-speed video analysis at 1000 Hz (difference: contact time +4.2%, flight time −11.3%). Accordingly, heteroscedasticity was found between systems for temporal parameters (<i>r</i><sup>2</sup>&gt;0.1). CONCLUSIONS The results indicate that the Kinect+MotionMetrix combination slightly overestimates contact time and strongly underestimates flight time as compared to the OptoGait system and high-speed video analysis at 1000 Hz. However, it is a valid tool for measuring step frequency and step length when compared to reference systems. Future studies should determine the reliability of this system for determining temporal parameters.

scholarly journals Agreement Between Spatiotemporal Gait Parameters Measured by a Markerless Motion Capture System and Two Reference Systems—a Treadmill-Based Photoelectric Cell and High-Speed Video Analyses: Comparative Study

10.2196/19498 ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. e19498
Author(s):  
Felipe García-Pinillos ◽  
Diego Jaén-Carrillo ◽  
Victor Soto Hermoso ◽  
Pedro Latorre Román ◽  
Pedro Delgado ◽  
...  
Keyword(s):  
Video Analysis ◽  
Contact Time ◽  
High Speed ◽  
Step Length ◽  
Flight Time ◽  
Reference Systems ◽  
Random Errors ◽  
Step Frequency ◽  
Temporal Parameters ◽  
High Speed Video

Background Markerless systems to capture body motion require no markers to be attached to the body, thereby improving clinical feasibility and testing time. However, the lack of markers might affect the accuracy of measurements. Objective This study aimed to determine the absolute reliability and concurrent validity of the Kinect system with MotionMetrix software for spatiotemporal variables during running at a comfortable velocity, by comparing data between the combination system and two widely used systems—OptoGait and high-speed video analysis at 1000 Hz. Methods In total, 25 runners followed a running protocol on a treadmill at a speed of 12 km/h. The Kinect+MotionMetrix combination measured spatiotemporal parameters during running (ie, contact time, flight time, step frequency, and step length), which were compared to those obtained from two reference systems. Results Regardless of the system, flight time had the highest coefficients of variation (OptoGait: 16.4%; video analysis: 17.3%; Kinect+MotionMetrix: 23.2%). The rest of the coefficients of variation reported were lower than 8.1%. Correlation analysis showed very high correlations (r>0.8; P<.001) and almost perfect associations (intraclass correlation coefficient>0.81) between systems for all the spatiotemporal parameters except contact time, which had lower values. Bland-Altman plots revealed smaller systematic biases and random errors for step frequency and step length and larger systematic biases and random errors for temporal parameters with the Kinect+MotionMetrix system as compared to OptoGait (difference: contact time +3.0%, flight time −7.9%) and high-speed video analysis at 1000 Hz (difference: contact time +4.2%, flight time −11.3%). Accordingly, heteroscedasticity was found between systems for temporal parameters (r2>0.1). Conclusions The results indicate that the Kinect+MotionMetrix combination slightly overestimates contact time and strongly underestimates flight time as compared to the OptoGait system and high-speed video analysis at 1000 Hz. However, it is a valid tool for measuring step frequency and step length when compared to reference systems. Future studies should determine the reliability of this system for determining temporal parameters.

Effects of Alternate Leading Edge Cutback on Unsteady Cavitation in 4-Bladed Inducers

2001 ◽  
Vol 123 (4) ◽  
pp. 762-770 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Yoshinobu Tsujimoto ◽  
Dai Kataoka ◽  
Hironori Horiguchi ◽  
Fabien Wahl
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Leading Edge ◽  
Cavitation Number ◽  
The Other ◽  
Low Flow ◽  
Pressure Measurements ◽  
High Speed Video ◽  
Cavitation Performance ◽  
Wide Range

A set of 4-bladed inducers with various amounts of cutback was tested with the aim of suppressing the rotating cavitation by applying alternate leading edge cutback. Unsteady cavitation patterns were observed by means of inlet pressure measurements and high-speed video pictures. It was found that the region with the alternate blade cavitation and asymmetric cavitation were enlarged with the increase of the amount of the cutback. As a result, the region with the rotating cavitation was diminished. At low flow rate, two types of alternate blade cavitation were found as predicted theoretically on 4-bladed inducer with smaller uneven blade length. One of them is with longer cavities on longer blades, and the other is with longer cavities on shorter blades. Switch was observed in these alternate blade cavitation patterns depending whether the cavitation number was increased or decreased. For an inducer with larger amount of cutback, the rotating cavitation and cavitation surge were almost suppressed as expected for a wide range of flow rate and cavitation number, although the cavitation performance was deteriorated. However, we should note that an asymmetric cavitation pattern occurs more easily in inducers with alternate leading edge cutback, and that the unevenness due to the cutback causes uneven blade stress.

Observations of Oscillating Cavitation of an Inducer

1997 ◽  
Vol 119 (4) ◽  
pp. 775-781 ◽  
Author(s):  
Yoshinobu Tsujimoto ◽  
Yoshiki Yoshida ◽  
Yasukazu Maekawa ◽  
Satoshi Watanabe ◽  
Tomoyuki Hashimoto
Keyword(s):  
High Speed ◽  
Pressure Fluctuations ◽  
Linear Analysis ◽  
Cavitation Number ◽  
Flow Coefficient ◽  
The Other ◽  
General View ◽  
Pressure Measurements ◽  
High Speed Video ◽  
Wide Range

Oscillating cavitation of an inducer was observed through unsteady inlet pressure measurements and by use of high speed video picture, covering a wide range of flow coefficient and cavitation number. One of the purposes of the study is to identify a mode of rotating cavitation predicted by a linear analysis, and the other is to obtain a general view of oscillating cavitation. The number of rotating cavitation cells and their propagation velocity were carefully determined from the phase difference of pressure fluctuations at various circumferential locations. Various kinds of oscillating cavitation were observed: rotating cavitation rotating faster/slower than impeller rotation, cavitation in backflow vortices, and surge mode oscillations. Effects of inlet and outlet (effective) pipelength were also studied.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

APPLICATION OF THE EARLY DAMAGE DIAGNOSTICS TECHNIQUE TO EXAMINATION OF THE AVIATION PANEL

2019 ◽  
Vol 85 (6) ◽  
pp. 53-63 ◽  
Author(s):  
I. E. Vasil’ev ◽  
Yu. G. Matvienko ◽  
A. V. Pankov ◽  
A. G. Kalinin
Keyword(s):  
Acoustic Emission ◽  
Damage Detection ◽  
High Speed ◽  
Early Stage ◽  
Video Data ◽  
High Speed Video ◽  
Damage Diagnostics ◽  
Subsurface Defect ◽  
Sensitive Coating ◽  
Early Damage

The results of using early damage diagnostics technique (developed in the Mechanical Engineering Research Institute of the Russian Academy of Sciences (IMASH RAN) for detecting the latent damage of an aviation panel made of composite material upon bench tensile tests are presented. We have assessed the capabilities of the developed technique and software regarding damage detection at the early stage of panel loading in conditions of elastic strain of the material using brittle strain-sensitive coating and simultaneous crack detection in the coating with a high-speed video camera “Video-print” and acoustic emission system “A-Line 32D.” When revealing a subsurface defect (a notch of the middle stringer) of the aviation panel, the general concept of damage detection at the early stage of loading in conditions of elastic behavior of the material was also tested in the course of the experiment, as well as the software specially developed for cluster analysis and classification of detected location pulses along with the equipment and software for simultaneous recording of video data flows and arrays of acoustic emission (AE) data. Synchronous recording of video images and AE pulses ensured precise control of the cracking process in the brittle strain-sensitive coating (tensocoating)at all stages of the experiment, whereas the use of structural-phenomenological approach kept track of the main trends in damage accumulation at different structural levels and identify the sources of their origin when classifying recorded AE data arrays. The combined use of oxide tensocoatings and high-speed video recording synchronized with the AE control system, provide the possibility of definite determination of the subsurface defect, reveal the maximum principal strains in the area of crack formation, quantify them and identify the main sources of AE signals upon monitoring the state of the aviation panel under loading P = 90 kN, which is about 12% of the critical load.

Assessment of Commercial Off-the-Shelf Tissue Adhesives for Sealing Military-Relevant Corneal Perforation Injuries

2021 ◽  
Author(s):  
Eric J Snider ◽  
Lauren E Cornell ◽  
Brandon M Gross ◽  
David O Zamora ◽  
Emily N Boice
Keyword(s):  
Intraocular Pressure ◽  
High Speed ◽  
Anterior Segment ◽  
Ocular Tissue ◽  
Corneal Tissue ◽  
Corneal Perforation ◽  
Tissue Adhesives ◽  
Open Globe ◽  
Wide Range ◽  
Commercial Off The Shelf

ABSTRACT Introduction Open-globe ocular injuries have increased in frequency in recent combat operations due to increased use of explosive weaponry. Unfortunately, open-globe injuries have one of the worst visual outcomes for the injured warfighter, often resulting in permanent loss of vision. To improve visual recovery, injuries need to be stabilized quickly following trauma, in order to restore intraocular pressure and create a watertight seal. Here, we assess four off-the-shelf (OTS), commercially available tissue adhesives for their ability to seal military-relevant corneal perforation injuries (CPIs). Materials and Methods Adhesives were assessed using an anterior segment inflation platform and a previously developed high-speed benchtop corneal puncture model, to create injuries in porcine eyes. After injury, adhesives were applied and injury stabilization was assessed by measuring outflow rate, ocular compliance, and burst pressure, followed by histological analysis. Results Tegaderm dressings and Dermabond skin adhesive most successfully sealed injuries in preliminary testing. Across a range of injury sizes and shapes, Tegaderm performed well in smaller injury sizes, less than 2 mm in diameter, but inadequately sealed large or complex injuries. Dermabond created a watertight seal capable of maintaining ocular tissue at physiological intraocular pressure for almost all injury shapes and sizes. However, application of the adhesive was inconsistent. Histologically, after removal of the Dermabond skin adhesive, the corneal epithelium was removed and oftentimes the epithelium surface penetrated into the wound and was adhered to inner stromal tissue. Conclusions Dermabond can stabilize a wide range of CPIs; however, application is variable, which may adversely impact the corneal tissue. Without addressing these limitations, no OTS adhesive tested herein can be directly translated to CPIs. This highlights the need for development of a biomaterial product to stabilize these injuries without causing ocular damage upon removal, thus improving the poor vision prognosis for the injured warfighter.

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