scholarly journals Kinematics Study of Depth Jump on Male Triple Jumpers with Slope Run-Up

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Youbao Ma
Keyword(s):  
Vertical Velocity ◽  
High Velocity ◽  
Three Dimensional ◽  
Video Camera ◽  
Horizontal Velocity ◽  
Training Methods ◽  
Lower Limb Muscles ◽  
Jump Exercise ◽  
Run Up ◽  
Takeoff Angle

Objective. To explore the training methods of developing the special strength of Chinese male triple jumpers through the experimental study of nine male triple-jumpers who performed step takeoff and depth long jump on the force platform. Methods. Through the combination of high-velocity shooting and a three-dimensional force measuring platform, the data of the athletes’ full run-up and depth jump landing, horizontal velocity, vertical velocity, takeoff time, landing angle, takeoff angle, and strength were obtained. In this study, the kinematics characteristics of four slopes with different slopes of 25 cm and 35 cm were studied. Kinematics’ data was measured by a high-velocity video camera. Results. The vertical velocity of the 35 cm platform is obviously less than that of the 25 cm platform p < 0.01 . The 25 cm platform is better at developing vertical, rapid takeoff ability, especially the fourth slope of this height, which is the fastest from horizontal velocity and vertical speed. All the depth jump practice ground angles are larger than the whole step jump, and the off-ground angle is smaller than the step jump, the takeoff time is larger than the step jump, which indicates that the athletes takeoff range is larger and the takeoff time is longer, and the results are in greater stimulation intensity of lower limb muscles. Conclusion. The 25 cm high platform depth jump exercise has achieved a better takeoff effect. Among the four slope depth jump exercises on this high platform, the 6.84 slope takeoff effect is the best.

Effects of a Knee Extension Constraint Brace on Selected Lower Extremity Motion Patterns during a Stop-Jump Task

2008 ◽  
Vol 24 (2) ◽  
pp. 158-165 ◽  
Author(s):  
Cheng-Feng Lin ◽  
Hui Liu ◽  
William E. Garrett ◽  
Bing Yu
Keyword(s):  
Vertical Velocity ◽  
Ground Reaction Force ◽  
Knee Flexion ◽  
Reaction Force ◽  
Three Dimensional ◽  
Knee Extension ◽  
Horizontal Velocity ◽  
Flexion Angle ◽  
Knee Flexion Angle ◽  
Extremity Motion

Small knee flexion angle during landing has been proposed as a potential risk factor for sustaining noncontact ACL injury. A brace that promotes increased knee flexion and decreased posterior ground reaction force during landing may prove to be advantageous for developing prevention strategies. Forty male and forty female recreational athletes were recruited. Three-dimensional videographic and ground reaction force data in a stop-jump task were collected in three conditions. Knee flexion angle at peak posterior ground reaction force, peak posterior ground reaction force, the horizontal velocity of approach run, the vertical velocity at takeoff, and the knee flexion angle at takeoff were compared among conditions: knee extension constraint brace, nonconstraint brace, and no brace. The knee extension constraint brace significantly increased knee flexion angle at peak posterior ground reaction force. Both knee extension constraint brace and nonconstraint brace significantly decreased peak posterior ground reaction force during landing. The brace and knee extension constraint did not significantly affect the horizontal velocity of approach run, the vertical velocity at takeoff, and the knee flexion angle at takeoff. A knee extension constraint brace exhibits the ability to modify the knee flexion angle at peak posterior ground reaction force and peak posterior ground reaction force during landing.

A Three-Dimensional Analysis of the Men’s Compulsory Vault Performed at the 1992 Olympic Games

1996 ◽  
Vol 12 (2) ◽  
pp. 237-257 ◽  
Author(s):  
Yoshiaki Takei ◽  
Erik P. Blucker ◽  
J. Hubert Dunn ◽  
Scott A. Myers ◽  
Virginia L. Fortney
Keyword(s):  
Kinetic Energy ◽  
Dimensional Analysis ◽  
Vertical Velocity ◽  
Olympic Games ◽  
Three Dimensional ◽  
Center Of Gravity ◽  
Horizontal Velocity ◽  
Frame Rate ◽  
The Third ◽  
Full Turn

The 20 highest scored handspring with full-turn vaults performed during the 1992 Olympic Games were compared with those receiving the 20 lowest scores. Hypotheses were that the vaults receiving high scores would (a) demonstrate larger horizontal velocity at takeoff from the board and larger vertical velocity at takeoff from the horse and (b) demonstrate greater amplitude of postflight, higher center of gravity (CG) at the completion of the full twist, and superior landing performance than those receiving low scores. Two 16-mm Locam II DC cameras, each operating at a nominal frame rate of 100 Hz, recorded the vaults. It was concluded that the vaults receiving high scores demonstrated (a) larger horizontal velocity and translational kinetic energy at takeoff from the board, larger vertical velocity and translational kinetic energy at takeoff from the horse, and greater amplitude of postflight; (b) greater heights of CG from the beginning of the second-quarter twist to halfway through the third-quarter twist; and (c) superior landing performance than those receiving low scores.

Combining SAR interferometry and the equation of continuity to estimate the three-dimensional glacier surface-velocity vector

1999 ◽  
Vol 45 (151) ◽  
pp. 533-538 ◽  
Author(s):  
Niels Reeh ◽  
Søren Nørvang Madsen ◽  
Johan Jakob Mohr
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
Vertical Velocity ◽  
Velocity Vector ◽  
Thickness Distribution ◽  
Vertical Surface ◽  
Horizontal Velocity ◽  
Sar Interferometry ◽  
Surface Velocity ◽  
Ice Thickness

AbstractUntil now, an assumption of surface-parallel glacier flow has been used to express the vertical velocity component in terms of the horizontal velocity vector, permitting all three velocity components to be determined from synthetic aperture radar interferometry. We discuss this assumption, which neglects the influence of the local mass balance and a possible contribution to the vertical velocity arising if the glacier is not in steady state. We find that the mass-balance contribution to the vertical surface velocity is not always negligible as compared to the surface-slope contribution. Moreover, the vertical velocity contribution arising if the ice sheet is not in steady state can be significant. We apply the principle of mass conservation to derive an equation relating the vertical surface velocity to the horizontal velocity vector. This equation, valid for both steady-state and non-steady-state conditions, depends on the ice-thickness distribution. Replacing the surface-parallel-flow assumption with a correct relationship between the surface velocity components requires knowledge of additional quantities such as surface mass balance or ice thickness.

scholarly journals Application of the erosion algorithm in modeling of structures behavior under impulse loads

2019 ◽  
Vol 221 ◽  
pp. 01003
Author(s):  
Pavel Radchenko ◽  
Stanislav Batuev ◽  
Andrey Radchenko
Keyword(s):  
Finite Element ◽  
High Velocity ◽  
Three Dimensional ◽  
Computer Software ◽  
Dynamic Loads ◽  
Complex Structures ◽  
Numerical Studies ◽  
Contact Surfaces ◽  
Fracture Of Materials ◽  
Solid Bodies

The paper presents results of applying approach to simulation of contact surfaces fracture under high velocity interaction of solid bodies. The algorithm of erosion -the algorithm of elements removing, of new surface building and of mass distribution after elements fracture at contact boundaries is consider. The results of coordinated experimental and numerical studies of fracture of materials under impact are given. Authors own finite element computer software program EFES, allowing to simulate a three-dimensional setting behavior of complex structures under dynamic loads, has been used for the calculations.

Internal-inertia waves in a fluid of variable depth

1973 ◽  
Vol 73 (1) ◽  
pp. 205-213 ◽  
Author(s):  
W. D. McKee
Keyword(s):  
Exact Solutions ◽  
Surface Waves ◽  
Internal Waves ◽  
Vertical Velocity ◽  
General Problem ◽  
Three Dimensional ◽  
Variable Depth ◽  
Internal Inertia ◽  
Perturbation Pressure ◽  
Rotating Stratified Fluid

AbstractWaves in a rotating, stratified fluid of variable depth are considered. The perturbation pressure is used throughout as the dependent variable. This proves to have some advantages over the use of the vertical velocity. Some previous three-dimensional solutions for internal waves in a wedge are shown to be incorrect and the correct solutions presented. A WKB analysis is then performed for the general problem and the results compared with the exact solutions for a wedge. The WKB solution is also applied to long surface waves on a rotating ocean.

Study on Magnetic Barrel Machine Equipped with Three-Dimensional Arrangement of Magnets

2007 ◽  
Vol 329 ◽  
pp. 761-766 ◽  
Author(s):  
Y. Zhang ◽  
Masato Yoshioka ◽  
Shin-Ichiro Hira
Keyword(s):  
High Speed ◽  
Permanent Magnets ◽  
Three Dimensional ◽  
Video Camera ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
The Media ◽  
Set Up

At present, a commercially available magnetic barrel machine equipped with permanent magnets has some faults arising from constructional reason. That is, grinding or finishing ability is different from place to place in the machining region, resulting in the limitation on the region we can use in the container of workpieces. Therefore, in this research, authors made the new magnetic barrel machine equipped with three dimensional (3D) magnet arrangement to overcome these faults. The grinding ability of the new 3D magnetic barrel machine converted was experimentally examined, and compared with that of the traditional magnetic barrel machine. As a result, it was shown that we can use much broader region in the new 3D machine. It was also shown that the grinding ability became higher. The distribution of barrel media in action was recorded by means of a high speed video camera. It was clarified that the media rose up higher and were distributed more uniformly in the container by the effect of the magnet block newly set up. It was supposed that this must be the reason for the above-mentioned improvement of grinding ability.

scholarly journals Run-Up Simulation of a Semi-Floating Ring Supported Turbocharger Rotor Considering Thrust Bearing and Mass-Conserving Cavitation

Lubricants ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 44
Author(s):  
Christian Ziese ◽  
Cornelius Irmscher ◽  
Steffen Nitzschke ◽  
Christian Daniel ◽  
Elmar Woschke
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Three Dimensional ◽  
Reliable Prediction ◽  
Two Phase ◽  
Hydrodynamic Bearings ◽  
Thrust Bearings ◽  
Run Up ◽  
The Impact

The vibration behaviour of turbocharger rotors is influenced by the acting loads as well as by the type and arrangement of the hydrodynamic bearings and their operating condition. Due to the highly non-linear bearing behaviour, lubricant film-induced excitations can occur, which lead to sub-synchronous rotor vibrations. A significant impact on the oscillation behaviour is attributed to the pressure distribution in the hydrodynamic bearings, which is influenced by the thermo-hydrodynamic conditions and the occurrence of outgassing processes. This contribution investigates the vibration behaviour of a floating ring supported turbocharger rotor. For detailed modelling of the bearings, the Reynolds equation with mass-conserving cavitation, the three-dimensional energy equation and the heat conduction equation are solved. To examine the impact of outgassing processes and thrust bearing on the occurrence of sub-synchronous rotor vibrations separately, a variation of the bearing model is made. This includes run-up simulations considering or neglecting thrust bearings and two-phase flow in the lubrication gap. It is shown that, for a reliable prediction of sub-synchronous vibrations, both the modelling of outgassing processes in hydrodynamic bearings and the consideration of thrust bearing are necessary.

scholarly journals Structure-controlled asperities of the 1920 Haiyuan M8.5 and 1927 Gulang M8 earthquakes, NE Tibet, China, revealed by high-resolution seismic tomography

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Quan Sun ◽  
Shunping Pei ◽  
Zhongxiong Cui ◽  
Yongshun John Chen ◽  
Yanbing Liu ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Tomography ◽  
High Velocity ◽  
Three Dimensional ◽  
Large Earthquake ◽  
Velocity Model ◽  
Tectonic Stress ◽  
Double Difference ◽  
Source Regions ◽  
Large Earthquakes

AbstractDetailed crustal structure of large earthquake source regions is of great significance for understanding the earthquake generation mechanism. Numerous large earthquakes have occurred in the NE Tibetan Plateau, including the 1920 Haiyuan M8.5 and 1927 Gulang M8 earthquakes. In this paper, we obtained a high-resolution three-dimensional crustal velocity model around the source regions of these two large earthquakes using an improved double-difference seismic tomography method. High-velocity anomalies encompassing the seismogenic faults are observed to extend to depths of 15 km, suggesting the asperity (high-velocity area) plays an important role in the preparation process of large earthquakes. Asperities are strong in mechanical strength and could accumulate tectonic stress more easily in long frictional locking periods, large earthquakes are therefore prone to generate in these areas. If the close relationship between the aperity and high-velocity bodies is valid for most of the large earthquakes, it can be used to predict potential large earthquakes and estimate the seismogenic capability of faults in light of structure studies.

Muscle Function and Coordination of Stair Ascent

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Nicole G. Harper ◽  
Jason M. Wilken ◽  
Richard R. Neptune
Keyword(s):  
Three Dimensional ◽  
Gluteus Maximus ◽  
Gluteus Medius ◽  
Patient Specific ◽  
Functional Roles ◽  
Stair Ascent ◽  
Lower Limb Muscles ◽  
Ankle Joints ◽  
Community Environments ◽  
Antagonistic Muscles

Stair ascent is an activity of daily living and necessary for maintaining independence in community environments. One challenge to improving an individual's ability to ascend stairs is a limited understanding of how lower-limb muscles work in synergy to perform stair ascent. Through dynamic coupling, muscles can perform multiple functions and require contributions from other muscles to perform a task successfully. The purpose of this study was to identify the functional roles of individual muscles during stair ascent and the mechanisms by which muscles work together to perform specific subtasks. A three-dimensional (3D) muscle-actuated simulation of stair ascent was generated to identify individual muscle contributions to the biomechanical subtasks of vertical propulsion, anteroposterior (AP) braking and propulsion, mediolateral control and leg swing. The vasti and plantarflexors were the primary contributors to vertical propulsion during the first and second halves of stance, respectively, while gluteus maximus and hamstrings were the primary contributors to forward propulsion during the first and second halves of stance, respectively. The anterior and posterior components of gluteus medius were the primary contributors to medial control, while vasti and hamstrings were the primary contributors to lateral control during the first and second halves of stance, respectively. To control leg swing, antagonistic muscles spanning the hip, knee, and ankle joints distributed power from the leg to the remaining body segments. These results compliment previous studies analyzing stair ascent and provide further rationale for developing targeted rehabilitation strategies to address patient-specific deficits in stair ascent.

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