A Three-Dimensional Cinematographic Analysis of the Tennis Serve

1986 ◽  
Vol 2 (4) ◽  
pp. 260-271 ◽  
Author(s):  
Bruce Elliott ◽  
Tony Marsh ◽  
Brian Blanksby
Keyword(s):  
High Speed ◽  
Angular Displacement ◽  
Three Dimensional ◽  
Distal Segment ◽  
High Speed Photography ◽  
Mean Velocity ◽  
Tennis Players ◽  
Shoulder Joints ◽  
Tennis Serve ◽  
Male Subjects

Three dimensional (3-D) high-speed photography was used to record the tennis service actions of eight elite tennis players. The direct linear transformation (DLT) method was used for 3-D space reconstruction from 2-D images recorded from laterally placed cameras operating at 200fps. Seven of the eight subjects initially positioned their center of gravity toward the front foot during the stance phase. When the elbow reached 90° in the backswing, the knees of the eight subjects were at or near their maximum attained flexion, and the upper arm was an extension of a line joining both shoulder joints. A mean maximum vertical shoulder velocity of 1.7ms−1during the leg drive produced a force at the shoulder that was eccentric to the racket-limb, thus causing a downward rotation of this limb as measured by a mean velocity of the racket of −5.8ms−1down the back. This leg drive increased the angular displacement of the loop and therefore provided a greater distance over which the racket could be accelerated for impact. All subjects swung the racket up to the ball, and all but one hit the ball with the racket angled slightly backward (M= 93.9°). An effective summation of body segments was apparent because resultant linear velocities showed an increase as the more distal segment endpoint approached impact, although all subjects decelerated the racket immediately prior to impact. Mean resultant ball velocities of 34.4ms−1for the female subjects and 42.4ms−1for the male subjects were achieved.

Age-Related Differences in Throwing Techniques Used by the Catcher in Baseball

1994 ◽  
Vol 6 (3) ◽  
pp. 225-235 ◽  
Author(s):  
Shinji Sakurai ◽  
Bruce Elliott ◽  
J. Robert Grove
Keyword(s):  
High Speed ◽  
High Performance ◽  
Age Groups ◽  
Three Dimensional ◽  
Transformation Method ◽  
High Speed Photography ◽  
Two Phase ◽  
Ball Speed ◽  
Age Related ◽  
Release Speed

Three-dimensional (3-D) high speed photography was used to record the overarm throwing actions of five open-age, four 18-year-old, six 16-year- old, and six 14-year-old high-performance baseball catchers. The direct linear transformation method was used for 3-D space reconstruction from 2-D images of the catchers throwing from home plate to second base recorded using two phase-locked cameras operating at a nominal rate of 200 Hz. Selected physical capacity measures were also recorded and correlated with ball release speed. In general, anthropometric and strength measures significantly increased through the 14-year-old to open-age classifications, while a range of correlation coefficients from .50 to .84 was recorded between these physical capacities and ball speed at release. While many aspects of the kinematic data at release were similar, the key factors of release angle and release speed varied for the different age groups.

Contributions of Upper Limb Segment Rotations during the Power Serve in Tennis

1995 ◽  
Vol 11 (4) ◽  
pp. 433-442 ◽  
Author(s):  
Bruce C. Elliott ◽  
Robert N. Marshall ◽  
Guillermo J. Noffal
Keyword(s):  
Upper Limb ◽  
High Velocity ◽  
High Performance ◽  
Three Dimensional ◽  
Linear Velocity ◽  
Upper Arm ◽  
Tennis Players ◽  
Instantaneous Position ◽  
Tennis Serve ◽  
Negative Role

In the high-velocity tennis serve, the contributions that the upper limb segments' anatomical rotations make to racket head speed at impact depend on both their angular velocity and the instantaneous position of the racket with respect to the segments' axes of rotation. Eleven high-performance tennis players were filmed at a nominal rate of 200 Hz by three Photosonics cameras while hitting a high-velocity serve. The three-dimensional (3-D) displacement histories of 11 selected landmarks were then calculated using the direct linear transformation approach, and 3-D individual segment rotations for the upper limb were calculated using vector equations (Sprigings, Marshall, Elliott, & Jennings, 1994). The major contributors to the mean linear velocity of the center of the racket head of 31.0 m · s-1 at impact were internal rotation of the upper arm (54.2%), flexion of the hand (31.0%), horizontal flexion and abduction of the upper arm (12.9%), and racket shoulder linear velocity (9.7%). Forearm extension at the elbow joint played a negative role (-14.4%) and reduced the forward velocity of the center of the racket at impact.

Experimental and Numerical Study of Hydrodynamic Cavitation of Orifice Plates with Multiple Triangular Holes

2012 ◽  
Vol 256-259 ◽  
pp. 2519-2522 ◽  
Author(s):  
Zhi Yong Dong ◽  
Qi Qi Chen ◽  
Yong Gang Yang ◽  
Bin Shi
Keyword(s):  
Velocity Profile ◽  
High Speed ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Orifice Plate ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Hydraulic Characteristics ◽  
Image Velocimetry

Hydraulic characteristics of orifice plates with multiple triangular holes in hydrodynamic cavitation reactor were experimentally investigated by use of three dimensional particle image velocimetry (PIV), high speed photography, electronic multi-pressure scanivalve and pressure data acquisition system, and numerically simulated by CFD software Flow 3D in this paper. Effects of number, arrangement and ratio of holes on hydraulic characteristics of the orifice plates were considered. Effects of arrangement and ratio of holes and flow velocity ahead of plate on cavitation number and velocity profile were compared. Distribution of turbulent kinetic energy and similarity of velocity profile were analyzed. And characteristics of cavitating flow downstream of the orifice plate were photographically observed by high speed camera. Also, a comparison with flow characteristics of orifice plate with hybrid holes (circle, square and triangle) was made.

Experiment and Numerical Simulation of Extrudate Swell in the Polymer Extrusion Process

2011 ◽  
Vol 314-316 ◽  
pp. 401-404 ◽  
Author(s):  
Min Zhang ◽  
Chuan Zhen Huang ◽  
Guo Wen Chen ◽  
Yu Xi Jia
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Three Dimensional ◽  
Simulation Method ◽  
Extrusion Process ◽  
High Speed Photography ◽  
The Finite Element Method ◽  
Polymer Extrusion ◽  
Extrudate Swell ◽  
Rate Profile

The extrudate swell of the polymer extrusion process was studied with the experiment and simulation method. The extrudate swell process was recorded by the high-speed photography apparatus. The swell rate at the different time was calculated. It is found that the extrudate swell rate increase at the first five seconds. The maximum swell rate is about 4.37%. The three-dimensional numerical simulation model of the experiment die path was founded. The extrusion process including the extrudate swell was simulated used the Finite Element Method. Such simulated results as the velocity vector, the shear rate profile and the end of the swell zone were analyzed. The extrudate swell end got by the simulation is similar with the experiment result.

scholarly journals On compression and damage evolution in two thermoplastics

2017 ◽  
Vol 473 (2197) ◽  
pp. 20160495 ◽  
Author(s):  
N. K. Bourne ◽  
S. C. Garcea ◽  
D. S. Eastwood ◽  
S. Parry ◽  
C. Rau ◽  
...  
Keyword(s):  
High Speed ◽  
Deformation Behaviour ◽  
Three Dimensional ◽  
Spatial And Temporal Variation ◽  
High Speed Photography ◽  
Radial Deformation ◽  
X Ray Imaging ◽  
Series Of Experiments ◽  
The Impact ◽  
Continuous Range

The well-known Taylor cylinder impact test, which follows the impact of a flat-ended cylindrical rod onto a rigid stationary anvil, is conducted over a range of impact speeds for two polymers, polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK). In previous work, experiments and a model were developed to capture the deformation behaviour of the cylinder after impact. These works showed a region in which spatial and temporal variation of both longitudinal and radial deformation provided evidence of changes in phase within the material. In this further series of experiments, this region is imaged in a range of impacted targets at the Diamond synchrotron. Further techniques were fielded to resolve compressed regions within the recovered polymer cylinders that showed a fracture zone in the impact region. The combination of macroscopic high-speed photography and three-dimensional X-ray imaging has identified the development of failure with these polymers and shown that there is no abrupt transition in behaviours but rather a continuous range of responses to competing operating mechanisms. The behaviours noted in PEEK in these polymers show critical gaps in understanding of polymer high strain-rate response.

A Biomechanical Comparison of the Multisegment and Single Unit Topspin Forehand Drives in Tennis

1989 ◽  
Vol 5 (3) ◽  
pp. 350-364 ◽  
Author(s):  
Bruce Elliott ◽  
Tony Marsh ◽  
Peter Overheu
Keyword(s):  
Single Unit ◽  
High Speed ◽  
High Performance ◽  
Wrist Joint ◽  
Three Dimensional ◽  
Elbow Flexion ◽  
Unit Group ◽  
Transformation Method ◽  
Mean Value ◽  
High Speed Photography

Three-dimensional (3-D) high-speed photography was used to compare different forehand techniques of high performance players. Subjects, who hit a topspin forehand drive with the hitting limb moving almost as a single unit (Gs: single-unit group), were compared with players whose individual segments of the upper limb moved relative to each other (Gm: multisegment group) when playing the same stroke. The Direct Linear Transformation method was used for 3-D space reconstruction from 2-D images recorded from laterally placed phase-locked cameras operating at 200 fps. A third Photosonics camera operating at 100 fps filmed from overhead. Significant differences between the groups were recorded at the shoulder and elbow joints at the completion of the backswing. Maximal elbow joint angular velocities occurred 0.06 sec prior to impact, with the Gm group recording a significantly higher mean value for elbow extension than the Gs group. At impact, however, the Gm group recorded a significantly higher level of elbow flexion than the Gs group and achieved a higher mean angular velocity at the wrist joint than the Gs group. The Gm group recorded a higher racket tip linear velocity at impact and higher postimpact ball velocity when compared to the Gs group. The Gm technique of racket movement produced higher racket and ball velocities for this group of high performance players.

A Study of Hydraulic Characteristics of Multi-Square-Hole Orifice Plates

2012 ◽  
Vol 256-259 ◽  
pp. 2470-2473 ◽  
Author(s):  
Zhi Yong Dong ◽  
Yong Gang Yang ◽  
Qi Qi Chen ◽  
Bin Shi
Keyword(s):  
High Speed ◽  
Particle Image ◽  
Three Dimensional ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Hydraulic Characteristics ◽  
System Pressure ◽  
Image Velocimetry ◽  
Working Section ◽  
Square Hole

This paper experimentally investigated hydraulic characteristics in working section of multi-square-hole orifice plates of hydrodynamic cavitation reactor by use of three-dimensional Particle Image Velocimetry (PIV) and High Speed Photography etc. Arrangements of holes in the orifice plates can be divided into diagonal, cross and checkerboard categories. The three-dimensional velocity distribution, pressure and cavitation characteristics for each arrangement of multi-hole orifice plates were measured by PIV system, pressure data acquisition system and high speed camera, and a comparison of hydraulic characteristics of the three categories of arrangements of the multi-hole orifice plates were made.

Flow Investigation Around a V-Sector Ball Valve

2001 ◽  
Vol 123 (3) ◽  
pp. 662-671 ◽  
Author(s):  
P. Merati ◽  
M. J. Macelt ◽  
R. B. Erickson
Keyword(s):  
High Speed ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Ball Valve ◽  
Operating Conditions ◽  
Mean Velocity ◽  
Model Flow ◽  
Flow Investigation ◽  
And Behavior ◽  
The Relationship

Experimental and computational methods were used to study the structure and behavior of the shedded vortices around a V-ball valve. Strouhal frequency for shedded vortices around the valve over a range of operating conditions and flow rates using water as the medium were measured. The information gathered in this study would help to predict at what operating conditions pipe ruptures might occur. A dynamic pressure transducer was used to determine the Strouhal frequency. LDV was used to measure the mean velocity and turbulence magnitudes. FLUENT was used to develop a two dimensional fluid dynamics model. Flow was visualized using high-speed video photography. A dominant large three-dimensional vortex downstream of the valve was detected. The centerline of this vortex is a shadow of the valve lip. A fifth degree polynomial describing the relationship between the Strouhal number and Reynolds number is obtained.

An Experimental Study on the Kinematics of a Skilled Service in Playing Tennis

2010 ◽  
Author(s):  
Seyed Mohammad Ahmadi ◽  
Elham Shirzad ◽  
Banafsheh Sajadi ◽  
Mehdi Cheraghi ◽  
Khashayar Haghighi
Keyword(s):  
Experimental Study ◽  
High Frequency ◽  
High Speed ◽  
Three Dimensional ◽  
Effective Parameters ◽  
Kinematic Parameters ◽  
Good Service ◽  
Tennis Players ◽  
Professional Tennis ◽  
Effective Service

This paper studies the effective parameters of a skilled service in playing tennis and determines their relationship with skill deals. Effective service in tennis plays an important role in gaining more desirable result and the most important factor of success in getting scores depends on the player’s skills in serving an effective service. The characteristics of a good service are the high speed of the ball and the precision of landing the ball. The several parameters affecting on these two characteristic in the service, are studied in this paper. Therefore, the Kinematic parameters of 8 Iranian professional tennis athletes of first division tennis league and also 8 non-professional Iranian athletes who exercise about 3 sessions a week were extracted. After land marking these athletes, by use of two high-frequency cameras, pictures were recorded when the tennis players were serving the services. The investigation on the results of these tests is performed by three dimensional motion analyses. The pictures are analyzed with the WinAnalyze software. Therefore, in this paper, the most important effective parameters in serving a successful service are detected.

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