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Andreieva Natalia Olehivna, Zhyrnov Oleksandr Valeriiovych, Salyamin Yuriy Mykolayovych. Features of the kinematics structure of ball throwing and catching techniques in rhythmic gymnastics at the stage of preliminary basic training. Journal of Education, Health and Sport. 2020;10(7):350-357. eISSN 2391-8306. DOI http://dx.doi.org/10.12775/JEHS.2020.10.07.037 https://apcz.umk.pl/czasopisma/index.php/JEHS/article/view/JEHS.2020.10.07.037 https://zenodo.org/record/4072066 The journal has had 5 points in Ministry of Science and Higher Education parametric evaluation. § 8. 2) and § 12. 1. 2) 22.02.2019. © The Authors 2020; This article is published with open access at Licensee Open Journal Systems of Nicolaus Copernicus University in Torun, Poland Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author (s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non commercial license Share alike. (http://creativecommons.org/licenses/by-nc-sa/4.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited. The authors declare that there is no conflict of interests regarding the publication of this paper. Received: 19.06.2020. Revised: 09.07.2020. Accepted: 31.07.2020. Features of the kinematics structure of ball throwing and catching techniques in rhythmic gymnastics at the stage of preliminary basic training Natalia Olehivna Andreieva, Oleksandr Valeriiovych Zhyrnov, Yuriy Mykolayovych Salyamin National University of Ukraine on Physical Education and Sport, Kyiv, Ukraine Abstract The purpose of the research is to study the features of the kinematics structure of the technique on throwing and catching ball by athletes engaged in rhythmic gymnastics at the stage of preliminary basic training. Research methods include analysis and generalization of data received from scientific and methodical literature, video shooting, biomechanical video-computer analysis of movements, method of expert assessment, methods of mathematical statistics. The contingent under study accounts for 20 gymnasts of the second youth category aged 9-10. The peculiarities of the kinematics structure of motor actions of gymnasts when performing two basic sets of ball exercises, which are learned at the stage of preliminary basic training, were examined. Research results and their discussion. Quantitative information was obtained about the indicators of the kinematics structure of the nodal elements for sports technique, associated with basic set of ball exercises: from two or three steps – throwing the ball in the "Cossack" jump – catching into the roll on both hands and back in rhythmic steps; and from two or three steps – throwing the ball in a jump touching in the ring – catching into the roll on both hands and back in rhythmic steps. Based on the indicators of biomechanical analysis of the two basic sets of ball exercises performed, the phase structure of exercises is specified and the key elements of sports technique of throwing and catching the ball are studied. For a more detailed analysis in both studies, we selected three nodal elements: the starting pose of the body (the moment of releasing the ball), the multiplication of the body pose (body position during the jump) and the final body pose (the moment of catching the ball). Conclusion. Objective quantitative biomechanical information about indicators of kinematics structure of nodal elements for sport technique consisting of basic set of ball exercises is received: from two-three steps – throwing the ball in the "Cossack" jump – catching into the roll on both hands and back in rhythmic steps; and from two or three steps - throwing the ball in a jump touching in the ring – catching into the roll on both hands and back in rhythmic steps. The obtained characteristics of the kinematics structure of the nodal elements of throwing and catching the ball during both basic exercises, can be used as model indicators for more effective technical training of young gymnasts. Conflict of interest. The authors state that there is no conflict of interest. The prospect of further research is associated with development of the models of nodal elements motor structure, used as sport technique for exercises with objects at the stage of specialized basic training. Key words: rhythmic gymnastics; ball; preliminary basic training; technique; kinematics structure of movements; nodal elements; starting pose; multiplication of poses; throwing, catching.

Cold expansion technology is an extended method used in aeronautics to increase fatigue life of holes and hence extending inspection intervals. During the cold expansion process, a mechanical mandrel is forced to pass along the hole generating compressive residual hoop stresses. The most widely accepted geometry for this mandrel is the tapered one and simpler options like balls have generally been rejected based on the non-conforming residual hoop stresses derived from their use. In this investigation a novelty process using multiple balls with incremental interference, instead of a single one, was simulated. Experimental tests were performed to validate the finite element method (FEM) models and residual hoop stresses from multiple balls simulation were compared with one ball and tapered mandrel simulations. Results showed that the use of three incremental balls significantly reduced the magnitude of non-conforming residual hoop stresses and the extension of these detrimental zone.

The trajectory of a soccer ball, kicked with a spin to curve it into the goal, is strongly influenced by aerodynamic factors such as the Magnus force. Several studies using a wind-tunnel and high-speed cameras have investigated the Magnus force acting on a spinning soccer ball. However, the exact effect of the Magnus force on the trajectory of a spinning soccer ball in free flight remains unclear. This study set out to use an optical three-dimensional motion-capture system to record the details of the flight of such a spinning soccer ball. The maximum curvature of the ball’s trajectory occurred in the middle of its flight. The sideways-directed Magnus force acting on the ball decreased as the ball’s speed decreased during the entire flight. Thus, it was concluded that the deflection of the trajectory of the ball decreases as the sideways-acting force decreases throughout the flight.

It is known that cell concretes are almost immediately destroyed under load, having reached certain critical stresses. Such kind of destruction is called a “catastrophic failure”. Process of crack formation is one of the main factors, influencing process of concrete destruction. Modern theory of crack formation is mainly based on the Griffith theory of destruction. However, the mentioned theory does not completely correspond to the structure of cell concrete with its cell structure, because the theory is intended for a solid body. The article presents one of the possible variants of modelling of the structure of cell concrete and gives some assumptions concerning the process of crack formation in such hollow, not solid environment.

this work considers questions of origin and formation of the Yaroslavl football club «Shinnik». The characteristic of infrastructure of the stadium is given, as it was planned to carry out its reconstruction initially by 2010 in honor of the millennium and further inclusion of stadium in the list of the cities in which the FIFA World Cup will be held is studied. Statistical data of victories and defeats in various years of existence of club are provided in work.

This paper discusses the development of a multi-directional, universal, electromagnetic energy harvester. The device is a ball consisting of two parts: a rigid spherical core with internal tubes, coils and magnets, and a flexible silicone-based shell holding a carrier fluid. The multi-directional aspect of the design comes from the device’s spherical shape. The harvester generates energy when subject to compressive force, by moving fluid through a tube, pushing a permanently magnetized ball through a coil wound around the tube. A combination of 3-D printed PLA plastic and molded silicone was used to produce a prototype. The energy harvester can be utilized in applications where there is an oscillating compression and it is not limited to certain applications due to its universal ball shape. It was tested at five different frequencies between 4–15 Hz on its four different outer sides producing electricity at a range of 17 to 44 mV.

To assess ball performance for research and development purposes requires greater understanding of the impact conditions a tennis ball experiences in professional tournament play. Ball tracking information taken from three consecutive years of an ATP 250 tour event played on hard court was analysed. The frequency of first serves, second serves, racket impacts and surface impacts was assessed per game and extrapolated to show how many impacts a single ball is subjected to. Where applicable the pre- and post-impact velocities and angles were found, and the distribution of each was analysed. In total, data from 65 matches comprising 1505 games were analysed. On average, each game contained 70.26 (±16.23) impacts, of which 9.23%, 3.16%, 37.78% and 49.83% were first serves, second serves, racket impacts and surface impacts, respectively. As a result, assuming all balls in play are used evenly, a single ball is expected to be subjected to 105 (±24) impacts over the course of the nine games that it is in play. The results of the investigation could be used to design a wear protocol capable of artificially wearing tennis balls in a way that is representative of professional play.

The football game is the most beloved sport among society, especially for its emotional and recreational worthiness. Dribbling is the most important ability. It is intended to be as the capability of keeping the ball afloat preventing it from touching the ground by using the two lower limbs. The most time the ball lingers afloat, the highest level the doer shows to have achieved. The main point of this research is to spot the most adequate educative method in dribbling. By confronting two different learning methods, I have tried to develop a way of making headways in the above process. On the one hand the cognitive approach in the scientific paradigm turns out to work with a fabricated set of rules within which the little boy must move, whereas in the eco-dynamic approach the heuristic way of learning is followed. The results give out two solutions: the first one shows an increasing ability pursued by gradual repetitions, beginning with a low degree of complexity up until a major difficulty; the last one aims at getting gratification on "no ruling" ground. In the first case, the players must stick to the coach's orders and timing conditions. In the second one the doers are just given the space and tools, neither timing nor conditions are set. They only have to express themselves as much as they like. Both methods grasp to the ordinary educational system.

The purpose of this study was to measure the aerodynamic force acting upon a soccer ball spun in a wind-tunnel test. In particular, we prepared two types of spinning soccer balls (air and motor types), measured the aerodynamic force on each, and examined the validity of the measurement method. In the case of the air-type spinning ball, the ball was made to spin by applying compressed air from an air compressor via an air duster. In the case of the motor-type spinning ball, a motor was placed at the middle inside the ball, and the ball was then automatically spun. First, both the air- and motor-type spinning balls demonstrated very strong spin-parameter ( Sp ) dependence with respect to drag during spinning. In addition, the side-force coefficient showed signs of linear increase as Sp increased in the motor-type spinning ball, whereas it increased along a slight curve in the air-type spinning ball. In particular, a negative Magnus effect was observed in the motor-type spinning ball when the Reynolds number was approximately 2.0 × 10 5 and Sp was approximately 0.14 (-0.007) and when the Reynolds number was approximately 2.2 × 10 5 and Sp was approximately 0.13 (-0.005).

The research aims at recognizing the significance of statistical differences in post test between both researched groups in learning and retaining some rhythmic movements with ball . The research adopts the experimental methodology for its convenience to the nature of the research . The research community includes the female students of college of physical education in Mosul university for the term (2011-2012 ) . The research sample includes (32) female students in the college . The sample is divided into two groups (experimental and control ) equal in number as (16) female students for each group by using a lottery method . The equivalence is done between both groups in the variables ( age , tallness , weight and some physical fitness elements ) . After using video imaging on female students performance , showing it to the individuals of the experimental group as a feedback and using the common style (ordinary ) on the control group for (8) weeks , post test is performed on both research groups to recognize the student degree of acquiring some rhythmic movements with ball . After two weeks , the test is done again with the same conditions to recognize the degree of retaining these movements . By processing the data statistically , the following results have been obtained : - The presence of statistical significant differences in the post test between both research groups in acquiring some rhythmic movements with ball and for the interest of the experimental group . - The presence of statistical significant differences in the post test between both research groups in retaining some rhythmic movements with ball and for the interest of the experimental group .

The ball indentation technique based on deforming a material with a spherical indenter is an useful non-destructive tool for evaluating mechanical properties from a very small volume of material. In this work, the indentation test carried out using a 1.0 mm diameter tungsten carbide ball to penetration depths of around 100-200 mu m is modeled using finite element (FE) method and analyzed for three steels having different yield stress and strain hardening exponent. The FE generated load-depth curve is compared and verified with the experimental load-depth data for the three materials. The role of the contact friction at the indenter-specimen interface on both the load-depth plot and indentation profile are examined. The development of pile-up/sink-in during indentation and its dependence on strain hardening characteristics of the material, contact friction and indentation depth are analyzed using the FE model. The indentation profiles obtained from simulation are compared with experimental profiles and the implication of pile-up phenomenon on accurate evaluation of stress-strain values from the experimental indentation load-depth data is discussed. (C) 2011 Elsevier Ltd. All rights reserved.

The purpose of this study was to compare the basic aerodynamic characteristics of a previously developed 8-panel soccer ball with those of a new 32-panel soccer ball by conducting wind tunnel tests. Experimental results show that the critical Reynolds number (Re) was approximately 3.3 × 105 for the 8-panel ball and approximately 2.4 × 105 for the new ball, i.e., the Re of the new ball was slightly lower than that of the 8-panel ball. We conclude that the aerodynamic drag coefficient of the new 32-panel ball is closer to that of a golf ball than an 8-panel ball.

An explicit finite element (FE) model of a tennis ball impact on a freely suspended racket was produced in Ansys/LS-DYNA 10.0. The geometry for the racket frame was reproduced in the FE model using a non-contact laser scanner. The model was validated against experimental data obtained using the fully automated International Tennis Federation Racket Power Machine. The root mean squared error between the model and experimental data was 1 m⋅s−1 for the rebound velocity of the ball for typical velocities of over 40 m⋅s−1. The method can be applied to different rackets and other sports equipment to determine rapidly the performance characteristics of new designs.

The purpose of this study is to analyze the basic aerodynamic characteristics of conventional balls and new balls, using a wind tunnel for the experiments. We found that the critical Reynolds number for conventional balls was approximately 270,000, and that for new balls was approximately 220,000. The drag coefficient of new balls at supercritical regime was about 0.17, showing a slightly higher value than for conventional balls. Comparing the deviation of coordinate values at the landing point of the ball in flight near the critical Reynolds regime, the new balls tended to have a smaller deviation than conventional balls.

The response of some blood immunity of constituents of (7) team handball player from the college of physical education (university of mosul ) , their mean Ages , Heights ,and Weights (24) SD + (1.15), (71.57) SD + (13.35), (176. 42) SD + (5.47) respectivlly. The procedures of the research included a pre and post competition. Measurment of the blood includes: Immunoglobulines (IgG – IgA) and complement (C3) by using (Radial Immunod Iffusion Test Kit) (RID) The study revealed no significant differences in Immunoglobulins (IgG – IgA) concentration, and in complement (C3) before and after competition.

Background: Cutaneous injury following impact of a high velocity ball to the skin may result in either erythema or purpura or both. The lesion typically appears as an annular ring of erythema with or without accompanying ecchymosis when the skin is contacted by a paintball, a ping pong ball, a racquetball or a squash ball. Purpose: To describe a girl with targetoid erythema following impact of a racquetball on her flank and back and to review other sports associated with this response to skin injury. Methods: PubMed was used to search the following terms, separately and in combination: ball, erythema, paint, ping pong, purpura, racquetball, sign, site, sports, squash, targetoid. All papers were reviewed and relevant manuscripts, along with their reference citations, were evaluated. Results: A 13-year-old girl developed an annular red ring surrounding a central area of normal appearing skin on her right flank and upper back where a racquetball traveling at a high velocity contacted her skin. Similar appearing lesions of targetoid erythema have been described at the cutaneous impact sites of either paintballs, ping pong balls, squash balls; in addition to erythema, purpura may also concurrently appear or subsequently develop at the contact location of the ball with the skin. Conclusions: Targetoid erythema is a pathognomonic cutaneous presentation resulting from the impact of either a paintball, ping pong ball, racquetball or squash ball—that is traveling at a high velocity—with a sport participant’s skin. The ball SITE (sports-induced targetoid erythema) sign is suggested as a unifying nomenclature to designate this unique, ball sport-associated, cutaneous dermatosis in athletes participating in sports in which high velocity impact of the ball with the skin may occur.

In ball sports, it is usually acknowledged that expert athletes track the ball more accurately than novices. However, there is also evidence that keeping the eyes on the ball is not always necessary for interception. Here we aimed at gaining new insights on the extent to which ocular pursuit performance is related to catching performance. To this end, we analyzed eye and head movements of nine subjects catching a ball projected by an actuated launching apparatus. Four different ball flight durations and two different ball arrival heights were tested and the quality of ocular pursuit was characterized by means of several timing and accuracy parameters. Catching performance differed across subjects and depended on ball flight characteristics. All subjects showed a similar sequence of eye movement events and a similar modulation of the timing of these events in relation to the characteristics of the ball trajectory. On a trial-by-trial basis there was a significant relationship only between pursuit duration and catching performance, confirming that keeping the eyes on the ball longer increases catching success probability. Ocular pursuit parameters values and their dependence on flight conditions as well as the eye and head contributions to gaze shift differed across subjects. However, the observed average individual ocular behavior and the eye-head coordination patterns were not directly related to the individual catching performance. These results suggest that several oculomotor strategies may be used to gather information on ball motion, and that factors unrelated to eye movements may underlie the observed differences in interceptive performance.

In this paper we study properties of complete sets and of completions of sets in Banach spaces, with relation to balls: in particular, we study conditions implying that a set is a ball, or it has a completion which is a ball. We also discuss some related simple properties considered in a few recent papers, a new similar property, and relations among classes of sets defined by them. Results are illustrated by several examples.

Fine finished steel ball set into a bearing have been needed in precision machinery field. Spin angle controlled ball lapping method developed recently, is to have an excellent performance to lap the ball in which V-groove lapping plates are separated into two parts and three plates are able to rotate independently. Present paper focuses on an effect of lapping plate geometry on finishing characteristics of the steel ball. It is found that Rcurved lapping plates constituting of V-groove have yielded greater stock removal than flat ones. Experiments show that the stock removal is dependent upon spin angle θ which is closely related to slipping distance of ball. Measurements of a sphericity of lapped ball indicate that the geometry of lapping plate has small effect with respect to improvement of it, but causes larger stock removal rate and very smooth surface.

Spin angle controlled ball lapping method developed recently, is to have an excellent performance to lap the ball, in which V-groove lapping plate are separated into two parts and three plates are able to rotate independently. However, lapping of ceramic ball such as a silicon nitride(Si3N4) ball is very hard to finish its ball. Present paper focuses on spin angle controlled grinding of the Si3N4 ball using a diamond wheel. It is found that spin controlled grinding is sufficient to finish the Si3N4 ball. Experiments show that larger spin angle θ yields both higher stock removal rate and lower surface roughness of the ball. Measurements indicate that a sphericity of the ball is closely related to spin angle θ of the ball.

It has been shown recently that cubature formulae for the unit sphere and for the unit ball are closely related; in particular, cubature formulae for the surface measure on the sphere correspond to formulae for the Chebyshev weight function on the ball. This provides a new method to generate cubature formulae on these regions. In this paper we construct a number of cubature formulae for the Chebyshev weight function on the unit ball in R 2 , and use them to derive new formulae for the surface measure on the sphere S2.

International audience; Planetary roller screws (PRS) have recently received more attention, compared to conventional ball screws.A 3D model is created of the axial stiffness and the frictional moment in the contact between the load transferring surfaces in the roller screw mechanism. The contact occurs between the screw and roller threads and between the nut and roller threads. The contact is analysed in the current work. A model of the tooth deformation of the thread is developed. At the same time, the load transfer of one thread to another was calculated according to measured geometry and form errors. This load transfer was analysed for each of the components. Over 100 calculations were performed varying all form errors statistically to obtain statistical information on the load transfer.

We state and prove a new refined Boas-type inequality in a setting with a topological space and generalσ-finite and finite Borel measures. As a consequence of the result obtained, we derive a new class of Hardy- and Pólya-Knopp-type inequalities related to balls inℝnand prove that constant factors involved in their right-hand sides are the best possible.

Golf club fitting is becoming a more and more precise science. In the last 10 years, a number of different devices have become available to club fitters for measuring either the flight of the golf ball (e.g. Trackman™ and Flightscope ® radar devices) or just the initial launch conditions (e.g. Vector Pro™ and 3Trak ® camera devices, Golf AchieverTM laser device). In 2008, PING released the nFlight ® fitting software to tie in with any of these devices, capture data, digitally analyze and scientifically compare every aspect of every shot taken by a golfer to provide the best possible golf club fitting. One challenge arising from this approach was how to account for large differences in golf ball construction and performance, both in the initial launch conditions immediately after impact and the resultant ball flight. In particular, many golf courses use various kinds of range balls in practice and fitting areas. To conduct a golf club fitting using data derived from these balls could be misleading and result in inappropriate club choices. For example, a driver fitting using an exceptionally high spin ball could result in a low loft and stiff shaft being chosen to minimize the spin rate when actually the high spin is due to the nature of the ball used in the fitting rather than aspects of the golfer’s swing. To account for these differences and ensure accurate data from a golf club fitting, the nFlight ® fitting software provides a way to convert launch data from one category of golf ball into another. So far over 60 different brands of ball have been subjected to static, robot and player comparison testing including at least 1500 shots hit by Ping Man, PING’s robotic testing machine. A cluster analysis was used to group similar golf balls into various categories and C# code in the nFlight ® fitting software was used to manage the data conversion. The poster describes the testing conducted, the methods behind the cluster analysis and the patent-pending nFlight ® fitting software application of the data conversion.

Some previous studies have reported the consistency of the model calculations of the impact force, angle of reflection, coefficient of restitution, and the ball speed and angular velocity after impact. The others have reported the theoretical analyses of the effect of friction for impact if the ball and the flat surface have friction, or not. But only few data from the previous research have reported the experimental measurement of the impact of the soccer ball, which is pressurized spherical elastic shell, against the flat surface which has friction. This study is primarily intended to find out the property of the characteristics of the friction force which is formed by the collision of the soccer ball against the materials used for the goalkeeper gloves, changing the impact speed from 10 to 30 m/s. The soccer balls shot out by the 3 rotors machine keep the angular velocity 0 and come into collision on the angle with the rectangular-shaped latex formed material used for the goalkeeper gloves on the force plate. The impact force is measured vertically and horizontally from the force plate. Getting the averaged impact force curves, we discussed about the feature of the friction force between the soccer ball and the latex formed material. In addition, we measured the surface texture of the latex formed material by using the laser displacement meter, and discussed the relationship between the friction force and the surface texture.

The non-linear velocity-dependent rolling friction coefficient between a rigid ball and soft surface was determined by instrumenting the ball with a triaxial gyroscope and converting the spin rate to translational velocity. The latter was differentiated numerically and the resulting translational acceleration was normalised to the gravitational acceleration in order to obtain the rolling friction coefficient. The rolling friction coefficient between a rigid sphere and a foam surface increased with velocity and consisted of three components: a sharp increase in friction coefficient at slow velocities, starting at the static rolling friction coefficient; a constant coefficient at medium velocities; and a coefficient increasing with velocity squared at higher velocities.

This paper discusses balls in partial b-metric spaces and cone metric spaces, respectively. Let $(X,p_{b})$ be a partial b-metric space in the sense of Mustafa et al. For the family △ of all $p_{b}$ -open balls in $(X,p_{b})$ , this paper proves that there are $x,y\in B\in\triangle$ such that $B'\nsubseteq B$ for all $B'\in\triangle$ , where B and $B'$ are with centers x and y, respectively. This result shows that △ is not a base of any topology on X, which shows that a proposition and a claim on partial b-metric spaces are not true. By some relations among ≪