scholarly journals Not Breathing During the Approach Phase Ameliorates Freestyle Turn Performance in Prepubertal Swimmers

2021 ◽  
Vol 3 ◽  
Author(s):  
Emanuela Faelli ◽  
Laura Strassera ◽  
Sara Ottobrini ◽  
Vittoria Ferrando ◽  
Ambra Bisio ◽  
...  
Keyword(s):  
Execution Time ◽  
The Body ◽  
Kinematic Parameters ◽  
Rotation Time ◽  
Negative Relationships ◽  
Approach Phase

This study compared the effects of two breathing conditions during the freestyle turn approach phase in swimmers. Thirty-four prepubertal swimmers (mean ± SD: 10.59 ± 0.97 years) were divided into two groups: No Breath (NB), not breathing at the last stroke, and Breath Stroke (BS). Swimmers performed three turns with 5 min of rest between the repetitions. Kinematic parameters were recorded with two underwater and two surface cameras. Total turn time (NB: 9.31 ± 1.34 s; BS: 10.31 ± 1.80 s; p = 0.049), swim-in time (NB: 3.89 ± 0.63 s; BS 4.50 ± 0.79 s; p = 0.02) and rotation time (NB: 2.42 ± 0.29 s; BS: 3.03 ± 0.41 s; p = 0.0001) were significantly shorter and swim-in distance [NB: 0.70 (0.58,0.77) m; BS: 0.47 (0.34,0.55) m; p = 0.0001], glide distance (NB: 1.06 ± 0.21 m; BS: 0.70 ± 0.20 m; p = 0.0001) and surfacing distance [NB: 1.79 (1.19,2.24) m; BS: 1.18 (0.82,1.79) m; p = 0.043] were significantly longer in NB than in BS. Moreover, speed-in (NB: 1.04 ± 0.14 m/s; BS: 0.93 ± 0.14 m/s; p = 0.031) and push-off speed (NB: 2.52 ± 0.30 m/s; BS: 1.23 ± 0.20 m/s; p = 0.001) were significantly higher in NB than in BS. Swim-in time was positively and negatively correlated with rotation time and glide distance, respectively, whilst negative relationships between total turn time and swim-in distance, total turn time and surfacing distance and total turn time and speed-in were found. Our study showed that in prepubertal swimmers not breathing at the last stroke during the approach phase positively affected kinematic parameters of the turn, allowing to approach the wall faster, rotate the body quicker, increase push-off speed, reduce turn execution time, thus improving overall turn performance.

scholarly journals KINEMATIC PARAMETERS OF JUMP SHOT IN ELITE MALE BASKETBALL PLAYERS

2019 ◽  
pp. 237
Author(s):  
Emilija Stojanović ◽  
Marko Radenković ◽  
Saša Bubanj ◽  
Ratko Stanković
Keyword(s):  
Body Height ◽  
The Body ◽  
Release Time ◽  
Kinematic Parameters ◽  
Basketball Players ◽  
The Relationship ◽  
Lower Angle

The primary aim of this study was to determine kinematic parameters of jump shot in elite male basketball players, by analyzing the release time for shooting, the angle of entry, and ball spin and. The secondary aim of this study was to examine possible differences in these kinematic parameters among the players associated with their playing position. Eighteen male basketball players (7 guards, 8 forwards, 3 centers) from six Serbian senior teams were tested. 94Fifty basketball sensor was used to obtain the following kinematic parameters of jump shot). The highest average measured values of shot release time were found in centres (1.23±0.23 s) and the lowest in guards (1.07±0.28 s), although these differences were not statistically significant. Further, centres had a lower angle of entry (36.6±2.08°) than guards (40.54±4.76°) and forwards (42.05±3.77°). The highest value of backspin was obtained by forwards (130±11.91 rotations / min). There were no significant differences between guards, forwards and centers in any kinematic variables (p>.01). The relationship between the body height and angle of entry was not significant (p>0.05). In conclusion, compared to centers, guards and forwards showed similar results for the examined variables. This evidence seems to support the theory that compared to guards and forwards centres have the weaker shooting techniques. Coaches should encourage all players, especially centers, to shoot from all positions.

scholarly journals Operation of the alula as an indicator of gear change in hoverflies

2011 ◽  
Vol 9 (71) ◽  
pp. 1194-1207 ◽  
Author(s):  
Simon M. Walker ◽  
Adrian L. R. Thomas ◽  
Graham K. Taylor
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Angular Acceleration ◽  
The State ◽  
The Body ◽  
Kinematic Parameters ◽  
Wing Kinematics ◽  
Change Mechanism ◽  
The Third ◽  
Gear Change

The alula is a hinged flap found at the base of the wings of most brachyceran Diptera. The alula accounts for up to 10 per cent of the total wing area in hoverflies (Syrphidae), and its hinged arrangement allows the wings to be swept back over the thorax and abdomen at rest. The alula is actuated via the third axillary sclerite, which is a component of the wing hinge that is involved in wing retraction and control. The third axillary sclerite has also been implicated in the gear change mechanism of flies. This mechanism allows rapid switching between different modes of wing kinematics, by imposing or removing contact with a mechanical stop limiting movement of the wing during the lower half of the downstroke. The alula operates in two distinct states during flight—flipped or flat—and we hypothesize that its state indicates switching between different flight modes. We used high-speed digital video of free-flying hoverflies ( Eristalis tenax and Eristalis pertinax ) to investigate whether flipping of the alula was associated with changes in wing and body kinematics. We found that alula state was associated with different distributions of multiple wing kinematic parameters, including stroke amplitude, stroke deviation angle, downstroke angle of incidence and timing of supination. Changes in all of these parameters have previously been linked to gear change in flies. Symmetric flipping of the alulae was associated with changes in the symmetric linear acceleration of the body, while asymmetric flipping of the alulae was associated with asymmetric angular acceleration of the body. We conclude that the wings produce less aerodynamic force when the alula is flipped, largely as a result of the accompanying changes in wing kinematics. The alula changes state at mid-downstroke, which is the point at which the gear change mechanism is known to come into effect. This transition is accompanied by changes in the other wing kinematic parameters. We therefore find that the state of the alula is linked to the same parameters as are affected by the gear change mechanism. We conclude that the state of the alula does indeed indicate the operation of different flight modes in Eristalis , and infer that a likely mechanism for these changes in flight mode is the gear change mechanism.

Comparison of Torque and Coupler-Driven Four-Bars as Solutions to Planar Four Position and Spherical Four Orientation Tasks

2009 ◽  
Author(s):  
David A. Perkins ◽  
Andrew P. Murray
Keyword(s):  
Internal Loading ◽  
The Body ◽  
Linear Actuator ◽  
Kinematic Parameters ◽  
Static Loads ◽  
Position Task ◽  
Actuation Method

This work presents a comparison between two actuation methods for planar and spherical four-bar mechanisms. The first is actuation by a torque applied at either of the fixed pivots. The second actuation method uses a linear actuator connected between ground and the coupler. For any four position task, planar or spherical, a one parameter set of dyads is found that may be used to guide the body through the four positions. Any two of these dyads, when coupled, define a potential four-bar solution to the task. A sampling across the set of all possible mechanisms that solve the four position task may be compared by analyzing the internal static loads of the four-bar mechanisms. The comparison was conducted to determine if coupler-driven four-bars have reduced internal loading when compared to torque-driven mechanisms. Four position tasks were used for comparison of mechanisms designed for the same task, under the assumption that the optimal torque-driven mechanism would have a different set of kinematic parameters than the optimal coupler-driven mechanism.

scholarly journals Kinematic Structure at the Early Flight Position in Ski Jumping

2012 ◽  
Vol 35 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Janez Vodičar ◽  
Milan Čoh ◽  
Bojan Jošt
Keyword(s):  
Horizontal Plane ◽  
The Body ◽  
Total Variance ◽  
Upper Body ◽  
Kinematic Parameters ◽  
Ski Jumping ◽  
Variable Angle ◽  
The Stability ◽  
Explained Common Variance ◽  
Very High

The purpose of our research was to establish the variability of correlation between the length of the jumps and selected multi-item kinematic variables (n=9) in the early flight phase technique of ski jumping. This study was conducted on a sample of elite Slovenian ski jumpers (N=29) who participated in the experiment on a jumping hill in Hinterzarten, Germany (HS95m) on the 20th of August, 2008. The highest and most significant correlations (p=0.01) with the length of the ski jump were found in the multi-item variable height of flying, which was also expressed with the highest level of stability of the explained total variance (TV) on the first factor (TV=69.13%). The most important characteristic of the aerodynamic aspect of early flight was the variable angle between the body chord and the horizontal axis with significantly high correlations (p<0.05). The stability of that aerodynamic factor was very high (TV=65.04%). The results were essentially similar for the multi-item variable angle between left leg and the horizontal axis (TV=61.88%). The rest of the multi-item kinematic variables did not have significant correlations with the multi-item variable length of jump. Only two more variables, the angle between the upper body and the horizontal plane (TV=53.69%), and the angle between left ski and left leg (TV=50.13%), had an explained common variance on the first factor greater than 50% of total variance. The results indicated that some kinematic parameters of ski jumping early flight technique were more important for success considering the length of the jump.

scholarly journals Geometric Parameter Calibration for a Cable-Driven Parallel Robot Based on a Single One-Dimensional Laser Distance Sensor Measurement and Experimental Modeling

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2392 ◽  
Author(s):  
XueJun Jin ◽  
Jinwoo Jung ◽  
Seong Ko ◽  
Eunpyo Choi ◽  
Jong-Oh Park ◽  
...  
Keyword(s):  
Position Control ◽  
Uncertainty Modeling ◽  
Parallel Robot ◽  
Parallel Robots ◽  
The Body ◽  
Robot Kinematics ◽  
Kinematic Parameters ◽  
Body Frame ◽  
Geometric Uncertainty ◽  
Calibration Methods

A cable-driven parallel robot has benefits of wide workspace, high payload, and high dynamic response owing to its light cable actuator utilization. For wide workspace applications, in particular, the body frame becomes large to cover the wide workspace that causes robot kinematic errors resulting from geometric uncertainty. However, appropriate sensors as well as inexpensive and easy calibration methods to measure the actual robot kinematic parameters are not currently available. Hence, we present a calibration sensor device and an auto-calibration methodology for the over-constrained cable-driven parallel robots using one-dimension laser distance sensors attached to the robot end-effector, to overcome the robot geometric uncertainty and to implement precise robot control. A novel calibration workflow with five phases—preparation, modeling, measuring, identification, and adjustment—is proposed. The proposed calibration algorithms cover the cable-driven parallel robot kinematics, as well as uncertainty modeling such as cable elongation and pulley kinematics. We performed extensive simulations and experiments to verify the performance of the suggested method using the MINI cable robot. The experimental results show that the kinematic parameters can be identified correctly with 0.92 mm accuracy, and the robot position control accuracy is increased by 58%. Finally, we verified that the developed calibration sensor devices and the calibration methodology are applicable to the massive-size cable-driven parallel robot system.

On the Effect of Exploiting GPUs for a More Eco-Sustainable Lease of Life

2015 ◽  
Vol 25 (01) ◽  
pp. 169-195 ◽  
Author(s):  
Giuseppe Scanniello ◽  
Ugo Erra ◽  
Giuseppe Caggianese ◽  
Camine Gravino
Keyword(s):  
Execution Time ◽  
Carbon Dioxide Emissions ◽  
Graphics Processing Unit ◽  
Original System ◽  
The Body ◽  
Software Systems ◽  
Processing Unit ◽  
Migration Strategy ◽  
It Systems ◽  
Target Architecture

It has been estimated that about 2% of global carbon dioxide emissions can be attributed to IT systems. Green (or sustainable) computing refers to supporting business critical computing needs with the least possible amount of power. This phenomenon changes the priorities in the design of new software systems and in the way companies handle existing ones. In this paper, we present the results of a research project aimed to develop a migration strategy to give an existing software system a new and more eco-sustainable lease of life. We applied a strategy for migrating a subject system that performs intensive and massive computation to a target architecture based on a Graphics Processing Unit (GPU). We validated our solution on a system for path finding robot simulations. An analysis on execution time and energy consumption indicated that: (i) the execution time of the migrated system is less than the execution time of the original system; and (ii) the migrated system reduces energy waste, so suggesting that it is more eco-sustainable than its original version. Our findings improve the body of knowledge on the effect of using the GPU in green computing.

scholarly journals A toolbox for automated video analysis of rodents engaged in string-pulling: Phenotyping motor behavior of mice for sensory, whole-body and bimanual skilled hand function

2019 ◽  
Author(s):  
Samsoon Inayat ◽  
Surjeet Singh ◽  
Arashk Ghasroddashti ◽  
Qandeel ◽  
Pramuka Egodage ◽  
...  
Keyword(s):  
Video Data ◽  
The Body ◽  
Whole Body ◽  
Hand Movements ◽  
Therapeutic Drug ◽  
Motor Disorders ◽  
Rodent Models ◽  
Kinematic Parameters ◽  
Body Angle ◽  
String Pulling

AbstractString-pulling in rodents (rats and mice) is a task in which animals make hand-over-hand movements to spontaneously reel in a string with or without a food reward attached to its end. The task elicits bilateral skilled hand movements for which rodents require little training. The task is suitable for phenotyping physiology and pathophysiology of sensorimotor integration in rodent models of neurological and motor disorders. Because a rodent stands in the same location and its movements are repetitive, the task lends itself to quantification of topographical and kinematic parameters for on-line tactile tracking of the string, skilled hand movements for grasping, and rhythmical bilateral forearm movements to advance the string. Here we describe a Matlab® based software with a graphical user interface to assist researchers in analyzing the video record of string pulling. The software allows global characterization of position and motion using optical flow estimation, descriptive statistics, principal component, and independent component analyses as well as temporal measures of Fano factor, entropy, and Higuchi fractal dimension. Based on image segmentation and object tracking heuristic algorithms, the software also allows independent tracking of the body, ears, nose, and forehands for estimation of kinematic parameters such as body length, body angle, head roll, head yaw, head pitch, movement paths and speed of hand movement. The utility of the task and that of the software is presented by describing mouse strain characteristics in string-pulling behavior of two strains of mice, C57BL/6 and Swiss Webster. Postural and skilled hand kinematic differences that characterize the strains highlight the utility of the task and assessment methods for phenotypic and neurological analysis of healthy and rodent models of diseases such as Parkinson’s, Huntington’s, Alzheimer’s and other neurological and motor disorders.Significance statementMouse models are used to investigate the physiology and pathophysiology of motor deficits observed in human neurological conditions, for testing substances for therapeutic drug development, and to investigate the role of neural systems and their genetic basis in the expression of behavior. Behavioral tasks involving unconditioned and natural behavior can provide rich insights into motor performance in animal models and analyses can be aided by the automated processing of video data for reliable quantification and high throughput.

scholarly journals KINEMATIC MODELING OF THE TECHNIQUE STALDER BACKWARD TO HANDSTAND ON THE UNEVEN BARS

2019 ◽  
pp. 031
Author(s):  
Emilija Petković
Keyword(s):  
Kinematic Model ◽  
Reference Points ◽  
The Body ◽  
Kinematic Modeling ◽  
Kinematic Parameters ◽  
Successful Performance ◽  
Axis Of Rotation ◽  
Successful Technique ◽  
Female Gymnasts ◽  
Clear Support

Optimizing the technique of successful performance is important for detecting different technique styles that occur in female gymnasts. The aims of this research were to define an optimal kinematic model of the Stalder backward to handstand on the uneven bars exercise, as well as factors that most greatly affect the successful performance of the selected exercise, performed at the 39th and 40th World Cups in Artistic Gymnastics in Maribor (SLO). The sample of participants consisted of eight female gymnasts who participated in the Finals and performed the above mentioned exercise. Kinematic parameters were determined by the use of the Ariel Performance APAS 3-D video system, and anthropometric 16 reference points with four body segments (foot, center of gravity of the body-CG, shoulder joint and head). CG was calculated based on the model presented by Winter in 2009. The results of the research defined the kinematic exercise model that requires four phases: 1) Upswing from a handstand position to balance the resistance front; 2) Downswing to upswing with clear support; 3) Lower vertical passing; 4) Swing to handstand position. Variability of the trajectory of referent points is necessary as an indication of the successful performance of the Stalder backward to handstand on the uneven bars technique. In the current research, the variability for the successful technique for CG trajectory values decreases from -0.767m to -1.045m, while the trajectory values of the shoulder point decrease from 0.689m to 0.488m under the axis of rotation. The information given could optimize the performance of other young gymnasts at all levels of performance.

Self-Propelled Swimming Simulations of Self-Assembling Smart Boxes

2014 ◽  
Author(s):  
Mohsen Daghooghi ◽  
Iman Borazjani ◽  
M. Amin Karami ◽  
Ehsan Tarkesh Esfahani
Keyword(s):  
Swimming Speed ◽  
Self Assembly ◽  
Fiber Composites ◽  
The Body ◽  
The Other ◽  
Body Motion ◽  
Kinematic Parameters ◽  
Self Assembling ◽  
Rapid Construction ◽  
Open Configuration

This paper presents self-propelled swimming simulations of a smart foldable structure capable of swimming and self-assembly for rescue or rapid construction missions, e.g., making temporary bridges. The open configuration of the robot is like a wide cross, which undulates like an eel to swim to a given location. Micro Fiber Composites (MFCs) attached to the surface of the foldable robot actuate the surfaces for swimming purpose. Once the robot arrives at the desired locations shape memory alloys will be activated to fold the robot to a box. To optimize the kinematics of the robot to achieve either highest speed or maximize efficiency during locomotion. self-propelled swimming simulations of the robot was carried out by varying two kinematic parameters: the body motion wavelength and the amplitude. The simulations shows that to achieve higher speed, higher wavelengths are more desirable, e.g., wavelength of 0.95L achieved 15% higher swimming speed relative to 0.65L (L is the swimmer’s length). In contrast, to achieve higher efficiency, lower wavelengths (0.65L) and higher undulation amplitude (0.15L) was 14% more efficient than the other swimmer with wavelength 0.95L and amplitude 0.1L.

scholarly journals Energy Mechanisms of Free Vibrations and Resonance in Elastic Bodies

2021 ◽  
Author(s):  
Yuriy Alyushin
Keyword(s):  
Kinetic Energy ◽  
Elastic Deformation ◽  
Elastic Energy ◽  
Forced Vibrations ◽  
The Body ◽  
Kinematic Parameters ◽  
Conservation Of Energy ◽  
Average Value ◽  
The Law ◽  
External Forces

The mechanisms of natural oscillations and resonance are described, considering the peculiarities of the transformation of elastic and kinetic energy in the implementation of the law of conservation of energy in local and integral volumes of the body, using the concept of mechanics based on the concepts of space, time and energy. When describing the motion in the Lagrange form, the elastic deformation energy of the particles is determined by the quadratic invariant of the tensor, whose components are the partial derivatives of Euler variables with respect to Lagrange variables. The increment of the invariant due to elastic deformation is represented as the sum of two scalars, one of which depends on the average value of the relative lengths of the edges of the particles in the form of an infinitesimal parallelepiped, the second is equal to the standard deviation of these lengths from the average value. It is shown that each of the scalars can be represented in the form of two dimensionless kinematic parameters of elastic energy, which participate in different ways in the implementation of the law of conservation of energy. One part of the elastic energy passes into kinetic energy and participates in the implementation of the law of conservation of energy for the body as a whole, considering external forces. The second part is not converted into kinetic energy but changes the deformed state of the particles in accordance with the equations of motion while maintaining the same level of the part of the elastic energy of the particles used for this. The kinematic parameters differ from the volume density of the corresponding types of energy by a factor equal to the elastic modulus, which is directly proportional to the density and heat capacity of the material and inversely proportional to the volume compression coefficient. Transverse, torsional, and longitudinal vibrations are considered free and under resonance conditions. The mechanisms of transformation of forced vibrations into their own after the termination of external influences and resonance at the superposition of free and forced vibrations with the same or similar frequency are considered. The formation of a new free wave at each cycle with an increase in the amplitude, which occurs mainly due to internal energy sources, and not external forces, is justified.

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