The purpose of this study was to identify the correlation between angle of the lead leg and ball veloc ity during throwing motion of female professional baseball players. Ball velocity and throwing ...motion were measured. The correlation between the ball velocity and each angle, the amount of change from FC to the maximum value were examined. A positive correlation was observed between ankle plantar flexion angle and ball velocity in the 14-49% section, and a negative correlation was observed with the amount of change in knee flexion. The hip flexion angle was positively correlated with the ball velocity in almost all sections and the hip adduction angle was 75% or later. In male players with high pitching ability, the knee flexion angle is maintained after FC. On the con trary, in female players who can throw fast ball, the amount of change in knee flexion was reduced by holding the ankle joint in the plantar flexion position after FC and suppressing the forward tilt of the lower leg. It is considered that female players who can throw the ball faster support the lead leg with larger hip flexion and adduction angle after the ball is released.
We aimed to determine the usefulness of release push test (RPT) in detecting shoulder pain in baseball players with throwing shoulder injury. Fifty-five baseball players with throwing shoulder injury ...were recruited. RPT entailed pushing the examinerʼs hand while simulating the hand position of releasing the ball during throwing. Full can, empty can test, hyper-external rotation test (HERT), Neer impingement sign, Hawkins impingement sign, and OʼBrien test were also performed. All tests were considered positive if shoulder pain was provoked during the test. The RPT positivity rate was 51%, which was the highest among all the tests. Ten patients had only RPT positive during the examination; it had the highest single positivity which was also seen with HERT. The players with RPT positivity reported significantly more shoulder pain after the cocking phase of throwing compared to players with HERT positivity who reported more shoulder pain in the cocking phase. This study suggested that RPT may be a useful pain provocation test to assess the start or change in strength of throwing because it showed high positivity rate and could detect specific pain in players with throwing shoulder injury.
Abstract KeywordsDesign considerations - electroplating troubleshooting- poor throwing power- anode’s shape The main objective of the electroplating process is coverage with uniform thickness ...distribution without any problem on the entire surface of the product, and it is difficult to obtain uniform thickness distribution with the appearance of some defects resulting from errors in the design process. To avoid these defects, design considerations shoud be observed regarding the shape of the product, racking, The shape of the anodes and heaters, the causes of the plating problems resulting from failure to observe the design considerations should be known as well, in addition to knowing how to solve them. Furthermore, obligatory design principles and critera should be determined.The process of electroplating is not a cheap process, especially in the case of plating with precious metals such as gold, which requires particular specifications.Good design allows the application of good coverage, and often small changes in design can be made to help greatly in simplifying the treatment process, avoid plating problems resulting from lack of observed design considerations and reduce costs.The designer must know the principles and design considerations that affect the quality of the coating process, as well as the causes of the problems of the electroplating process in order to avoid them since the beginning of the design.Statement of Problem The research problem lies in the necessity for the designer to know the design considerations affecting the electroplating process, which results from not taking into account several problems, as well as to know how to treat them in order to reach a quality surface for the product at the lowest costs.PurposeThe purpose is to conduct an analytical study to find out the causes of some of the problems of electroplating resulting from failure to observe the design considerations regarding the shape of the product, racking, the shape of the anode and heaters and how to treat them.Research HypothesesTaking into account design considerations regarding the product shape, racking, and the shape of anode and heaters leads to: Avoiding many electroplating problems of different solutions. Achieving better results at the lowest costs
The use of new combination of additives such as cetyltrimethylammonium bromide (CTAB), benzoic acid (BA) and 2-bromo-3-chloro-5, 5-dimethylcyclohex-2-enone (BCD) develops bright zinc electrodeposit ...on mild steel. The additives combination has a synergistic effect on improving faradaic efficiency as well as throwing power of optimized bath. The morphology, orientation and anti-corrosion property of zinc electrodeposit has been systematically studied in absence and presence of individual and mixture of additives. The presence of all the three additives such as CTAB, BA and BCD in plating bath form nanocrystalline, bright zinc coating with (100), (110) preferred orientation with smaller surface roughness and superior anticorrosion property. The presence of any two additive mixtures out of three as well as single additive gave deposit with lower corrosion resistance. The influence of brightener BCD concentration on morphology, orientation and anti-corrosion property of bright zinc coating in optimum bath has been examined.
•Zinc electrodeposition using combination of additives like CTAB, BA and BCD.•Nanocrystalline zinc coating with (100)(110) preferred orientation was achieved.•Optimized bath deposit irregular objects uniformly with good efficiency.•Developed bright zinc coating showed good corrosion resistance.
Vibrating machinery with an elliptical trajectory widely exists. The bulk particles show a regular sliding motion and throwing motion under the periodic vibration of the frame. It is essential for ...the theoretical design and engineering application of such machinery to study the particle's motion theory based on considering the interactions between particles and frame in detail. In the first, a time‐varying piecewise nonlinear dynamic model of the system is established based on the force analysis of the particles in the state of sliding and throwing motion. The dimensionless equations of systems with nonlinear terms are deduced. After that, the feasibility of using a single particle to study the particle flow's movement is verified by the discrete element method. Then, the system's approximate steady‐state analytical solution is obtained by the incremental harmonic balance method. Its numerical solutions are solved by the Newmark‐β method, and the solutions obtained by the three methods are verified mutually. In addition, the Sommerfeld effect in vibration system and the system's related parameters are analyzed. Finally, an experimental platform of particles' movement is built. The feasibility of the theoretical analysis in this article was verified by particle's movement experiments.
Currently, it is not fully understood how motor variability is regulated to ease of motor learning processes during reward-based tasks. This study aimed to assess the potential relationship between ...different dimensions of motor variability (i.e., the motor variability structure and the motor synergies variability) and the learning rate in a reward-based task developed using a two-axis force sensor in a computer environment. Forty-four participants performed a pretest, a training period, a posttest, and three retests. They had to release a virtual ball to hit a target using a vertical handle attached to a dynamometer in a computer-simulated reward-based task. The participants’ throwing performance, learning ratio, force applied, variability structure (detrended fluctuation analysis, DFA), and motor synergy variability (good and bad variability ratio, GV/BV) were calculated. Participants with higher initial GV/BV displayed greater performance improvements than those with lower GV/BV. DFA did not show any relationship with the learning ratio. These results suggest that exploring a broader range of successful motor synergy combinations to achieve the task goal can facilitate further learning during reward-based tasks. The evolution of the motor variability synergies as an index of the individuals’ learning stages seems to be supported by our study.
The prevalence of impaired foot function and floating toes of 91 baseball players with disabled throwing shoulder or elbow were retrospectively investigated. Foot function was evaluated by foot "rock ...paper scissors" and floating toes were confirmed if none of the toes made contact with the mat in standing posture. The prevalence of impaired foot function and floating toes and the relationship between between them were determined. Abnormal foot function was observed in 83 players (91%); of those, 73 players (88%) also had floating toes, and the prevalence was statistically significant compared to those without it (12%) (P < 0.001). Floating toes were observed in 74 players (81%); of those, 73 players (99%) had impaired foot function, and the prevalence was also statistically significant compared to those without them (59%) (P < 0.001). Baseball players with disabled throwing shoulder or elbow have high rates of impaired foot function and floating toes.
At high speed launching of bodies via smoothbore throwing facility into water, a stabilization of bodies was experimentally achieved due to periodical interactions of body contour with the cavity ...boundaries. If the body contours are not exceeding produced cavity boundary, drag force localized mostly at nose part of a body, which calls “cavitator”. Based on this, it will be rational to take into consideration cavity shape when designing contours of bodies.
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