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.

An auxiliary approach to the experimental study on chip control: A kinematically simulated test

1998 ◽  
Vol 212 (2) ◽  
pp. 159-166 ◽  
Author(s):  
N Fang
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Cutting Tools ◽  
Three Dimensional ◽  
Experimental Period ◽  
Machining Processes ◽  
Chip Breaking ◽  
Chip Flow ◽  
Simulated Test ◽  
On Chip

Traditionally, cutting tools made of sintered carbides or high-speed steels are used to cut a variety of metal materials in the experimental study on chip control. One of the existing problems is that, in most cases, it is difficult to make, in a laboratory, cutting tools with a three-dimensionally shaped chip breaking groove for use in the follow-up experiments. Turning to tool manufacturers, who use the powder metallurgy techniques of tool making for help, usually leads to a long experimental period and high cost. An auxiliary approach to the experimental study on chip control, called a kinematically simulated test (KST), is proposed in this present work to overcome the above shortcoming of the traditional method employed in the experimental study on chip control. A plexiglass-made cutting tool is employed to cut a commercially available paraffin wax to simulate some kinematic phenomena (such as chip flow and chip curl) which take place during practical machining processes. After the applied range of KST has been illustrated, two examples of applying KST are given. One is the application of KST to chip flow research. The other is optimizing the geometry of the chip breaking groove of a tool insert by means of KST. Both examples involve the making of the chip breaking grooves with the three-dimensional shape and geometry.

Experimental Study on Gravity Driven Discharging of Quasi-Two-Dimensional Pebble Bed Based on Mathematical Morphology

2020 ◽  
Author(s):  
Yujia Liu ◽  
Sifan Peng ◽  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
...  
Keyword(s):  
Experimental Study ◽  
Mathematical Morphology ◽  
High Speed ◽  
Three Dimensional ◽  
Reactor Core ◽  
Engineering Application ◽  
Discharge Process ◽  
Two Dimensional ◽  
Pebble Bed ◽  
Gravity Driven

Abstract The pebbles flow is a fundamental issue for both academic investigation and engineering application in reactor core design and safety analysis. In general, experimental methods including spiral X-ray tomography and refractive index matched scanning technique (RIMS) are applied to obtain the identification of particles’ positions within a three-dimensional pebble bed. However, none of the above methods can perform global bed particles’ position identification in a dynamically discharging pebble bed, and the corresponding experimental equipment is difficult to access due to the complication and high expense. In this research, the experimental study is conducted to observe the gravity driven discharging process in the quasi two-dimensional silos by making use of the high-speed camera and the uniform backlight. A mathematical morphology-based method is applied to the pre-processing of the captured results. After being increased the gray value gradient by the threshold segmentation, the edges of the particles are identified and smoothed by the Sobel algorithm and the morphological opening operation. The particle centroid coordinates are identified according to the Hough circle transformation of the edges. For the whole pebble bed, the self-programmed process has a particle recognition accuracy of more than 99% and a particle centroid position deviation of less than 3%, which can accurately obtain the physical positions of all particles in the entire dynamically discharge process. By analyzing the position evolution of individual particles in consecutive images, velocity field and motion events of particles are observed. The discharging profiles of 5 conditions with different exit are analyzed in this experiment. The results make a contribution to improving the understanding of the mechanism of pebbles flow in nuclear engineering.

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.

Comparative Feature Analysis of Ground Surface Vibration Induced by High-Speed Train Running on Viaduct and Embankment

2014 ◽  
Vol 638-640 ◽  
pp. 1229-1232
Author(s):  
Kun Ming Mao ◽  
Ting Ting Wang ◽  
Qian Wen Ru ◽  
Yan Li
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
High Speed ◽  
Fourier Spectrum ◽  
Three Dimensional ◽  
Low Frequency ◽  
Ground Surface ◽  
Vertical Acceleration ◽  
High Frequency Band ◽  
Surface Vibration

Based on the Abaqus parallel computing cluster system platform, the three-dimensional finite element model of train-track-viaduct/embankment-foundation-soil coupling is established. The three-dimensional space-time variation and Fourier spectrums characters of ground surface vibration vertical accelerations by high-speed train running on viaduct and embankment are simulated. The result shows that ground surface vibration is mainly excited by periodic axle force of the train in the site near the viaduct pier. In the site far from the viaduct pier, ground surface vibration is mainly from the transmission of the site near the viaduct pier. With the increased distance between the viaduct pier, the peak value of ground surface vibration vertical acceleration decreases, and decreases significantly when the distance is within 10m. There are two main frequency bands of Fourier spectrum of ground surface vibration vertical acceleration: low-frequency band 0-12Hz and high-frequency band 35-47Hz of viaduct route, and low-frequency band 0-21Hz and high-frequency band 25-45Hz of embankment route. In general, with the increased distance between viaduct/embankment, Fourier spectrum amplitude of every frequency band decrease, and attenuation speed of high-frequency band is much faster than-frequency band’s.

Analysis on Rotating Dynamics of Tennis

2012 ◽  
Vol 246-247 ◽  
pp. 487-491
Author(s):  
Yi Qing Qian ◽  
Zu Jian Qiu
Keyword(s):  
Process Optimization ◽  
High Speed ◽  
Tennis Player ◽  
Bottom Up ◽  
Tennis Players ◽  
Shoulder Movement ◽  
Professional Tennis ◽  
Research Objects

High speed torque is very important in tennis batting process , this paper discusses the shoulder and torso rotation torque generated by the weight of tennis sports influence. Taking 48 tennis players as research objects, the rotation torque of professional tennis players are relatively outstanding with performance value,so we concluded that in the case of keeping the torso erect and through the process optimization of the rotation, we could combined shoulder movement and body bottom-up movement. These results suggested that some given hitting model can not only increase the performance of the tennis player on the pitch, but also reduce the risk of causing excessive damage.

Biomedical Application of Multimodal Ultrasound Microscope

2012 ◽  
pp. 27-35
Author(s):  
Yoshifumi Saijo
Keyword(s):  
Acoustic Impedance ◽  
High Frequency ◽  
Sound Speed ◽  
High Speed ◽  
Biomedical Application ◽  
3D Structure ◽  
Three Dimensional ◽  
Single Pulse ◽  
Frequency Domain Analysis ◽  
High Frequency Ultrasound

High frequency ultrasound imaging has evolved from the classical acoustic microscope to the multimodal ultrasound microscope, which is available for quantitative C-mode, surface acoustic impedance mode, and three-dimensional (3D)-mode imaging. This evolution has realized both quantitative parametric imaging and easier observation. Quantitative C-mode represents two-dimensional sound speed distribution and is realized by frequency-domain analysis of a single pulse by a high-speed digitizer. Because the square of sound speed is proportional to tissue elasticity, sound speed imaging provides biomechanical information about the tissue. Surface acoustic impedance mode has been used to image fresh brain tissue. High-frequency 3D-mode imaging has been used to visualize the 3D structure of dermis sebaceous glands.

High-speed brightfield 3-D imaging and 3-D image analysis of thick and overlapped cell clusters in cytological preparations

1994 ◽  
Vol 52 ◽  
pp. 218-219
Author(s):  
Robert W. Mackin
Keyword(s):  
Image Analysis ◽  
High Speed ◽  
Three Dimensional ◽  
Image Data ◽  
Ccd Camera ◽  
Objective Lens ◽  
Array Processor ◽  
Vaginal Smears ◽  
Low Contrast ◽  
Computer Controlled

This paper presents two advances towards the automated three-dimensional (3-D) analysis of thick and heavily-overlapped regions in cytological preparations such as cervical/vaginal smears. First, a high speed 3-D brightfield microscope has been developed, allowing the acquisition of image data at speeds approaching 30 optical slices per second. Second, algorithms have been developed to detect and segment nuclei in spite of the extremely high image variability and low contrast typical of such regions. The analysis of such regions is inherently a 3-D problem that cannot be solved reliably with conventional 2-D imaging and image analysis methods.High-Speed 3-D imaging of the specimen is accomplished by moving the specimen axially relative to the objective lens of a standard microscope (Zeiss) at a speed of 30 steps per second, where the stepsize is adjustable from 0.2 - 5μm. The specimen is mounted on a computer-controlled, piezoelectric microstage (Burleigh PZS-100, 68/μm displacement). At each step, an optical slice is acquired using a CCD camera (SONY XC-11/71 IP, Dalsa CA-D1-0256, and CA-D2-0512 have been used) connected to a 4-node array processor system based on the Intel i860 chip.

Articulatory Behavior Pre and Post Full-Mouth Tooth Extraction and Alveoloplasty

1980 ◽  
Vol 23 (3) ◽  
pp. 630-645 ◽  
Author(s):  
Gerald Zimmermann ◽  
J.A. Scott Kelso ◽  
Larry Lander
Keyword(s):  
Control Subject ◽  
High Speed ◽  
Tooth Extraction ◽  
Kinematic Parameters ◽  
Experimental Conditions ◽  
Mean Values ◽  
Articulatory Movements ◽  
The Mean ◽  
Experimental Subjects ◽  
Normal Speech

High speed cinefluorography was used to track articulatory movements preceding and following full-mouth tooth extraction and alveoloplasty in two subjects. Films also were made of a control subject on two separate days. The purpose of the study was to determine the effects of dramatically altering the structural dimensions of the oral cavity on the kinematic parameters of speech. The results showed that the experimental subjects performed differently pre and postoperatively though the changes were in different directions for the two subjects. Differences in both means and variabilities of kinematic parameters were larger between days for the experimental (operated) subjects than for the control subject. The results for the Control subject also showed significant differences in the mean values of kinematic variables between days though these day-to-day differences could not account for the effects found pre- and postoperatively. The results of the kinematic analysis, particularly the finding that transition time was most stable over the experimental conditions for the operated subjects, are used to speculate about the coordination of normal speech.

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