Seam Orientation Research Articles

Impart backspin and pitch the ball up: strategies cricket fast bowlers can employ to generate late swing

ABSTRACT In cricket fast bowling, late swing can increase interception difficulty for opposition batters. However, little is known about the occurrence and cause of late swing. This study investigated ball kinematics and the effect of changing kinematics on late swing with new cricket balls. Markers were placed on the ball to track the trajectory and calculate kinematics u1sing a motion analysis system. Fast bowlers generated varying ball kinematics (linear velocity, angular velocity and seam orientation) and delivery trajectories. A random intercept linear mixed-effects model identified that decreasing ball velocity (release velocity: effect = 0.21, p = 0.051, and pitch velocity: effect = -0.27, p = 0.011) and increasing seam stability (release stability: effect = -0.02, p < 0.001 and pitch stability: effect = 0.02, p = 0.001) were associated with greater late swing. To achieve these changes and create late swing, bowlers can pitch the ball on a full length and impart a large amount of backspin on the ball. However, swing can be influenced by factors such as wind and ball composition and late swing may be difficult to control. Bowlers and coaches should develop strategies to generate late swing but recognise it may be unpredictable in some situations.

Erratum to “The influence of seam orientation on the lift and drag of a rotating baseball in flight”

Erratum to “The influence of seam orientation on the lift and drag of a rotating baseball in flight”

Inter- and intra-athlete technique variability of conventional new ball swing bowling in elite and pre-elite Australian male fast bowlers

ABSTRACT This study aimed to investigate inter- and intra-athlete technique variability in pre-elite and elite Australian fast bowlers delivering new ball conventional swing bowling. Ball grip angle and pelvis, torso, shoulder, elbow, wrist, upper arm, forearm, and hand kinematics were investigated at the point of ball release for inswing and outswing deliveries. Descriptive evaluations of group and individual data and k-means cluster analyses were used to assess inter- and intra-bowler technique variability. Inter-athlete technique and ball grip variability were identified, demonstrating that skilled bowlers use individualised strategies to generate swing. Functional movement variability was demonstrated by intra-athlete variability in successful swing bowling trials. Bowlers demonstrated stable technique parameters in large proximal body segments of the pelvis and torso, providing a level of repeatability to their bowling action. Greater variation was observed in bowling arm kinematics, allowing athletes to manipulate the finger and ball position to achieve the desired seam orientation at the point of ball release. This study demonstrates that skilled bowlers use individualised techniques and grips to generate swing and employ technique variations in successive deliveries. Coaches should employ individualised training strategies and use constraints-led approaches in training environments to encourage bowlers to seek adaptive movement solutions to generate swing.

The influence of seam orientation on the lift and drag of a rotating baseball in flight

The effect of seam orientation relative to the spin axis on the forces of a rotating baseball has been studied, and debated, for as long as baseball has existed. Early debates centered on whether a spinning baseball could even curve and eventually changed to whether the orientation of seams had any impact on the forces acting on the ball during flight. This study uses Computational Fluid Dynamics to show that the seam orientation can have a significant influence on the lift force experienced by a baseball in flight, but that influence diminishes as the rate of spin approaches the natural shedding frequency of a sphere of the same size. Oscillations in the wake caused by the passing of seams across the upper and lower surface eventually give way to larger scale instabilities and the impact of seam orientation on the forces acting on the ball is significantly reduced.

Research on 3D curved weld seam trajectory position and orientation detection method

The "teaching-reproduction" mode and off-line programming mode are widely used in traditional welding robots. For curved welding workpieces, the operators need to visually inspect the position and orientation of the weld seam during processing to select the teaching points or the starting point for programming. The welding accuracy depends on the operators’ experience. Re-teaching or re-programming is required after adjusting the welding position or orientation, resulting in poor welding accuracy and efficiency. To enhance the adaptability of the robot to various welding conditions, we propose a 3D curved weld seam trajectory position and orientation detection method. A local welding workpiece point cloud is obtained by laser vision sensor scanning. The point cloud is smoothed by using the moving least squares (MLS) method. The surface variation of each point is calculated, and the surface variation threshold is set to extract the weld seam feature points. The weld seam orientation is calculated by solving the basic vectors of the spatial curve according to the parametric equation of the weld seam trajectory. The rotation angles of the robot are calculated by the transformation matrix between the weld seam local coordinate system and the robot base coordinate system. According to the experiments, the proposed method can adapt to various orientations of the curved welding workpiece and improve the robot's adaptability to orientations, therefore, the accuracy and efficiency of welding will be enhanced.

How do athletes cause ball flight path deviation in high-performance interceptive ball sports? A systematic review

Athletes alter ball flight trajectory in interceptive ball sports to change task constraints that their opponents must overcome to successfully meet the ball in flight. This systematic review identified how athletes change their techniques to alter the ball flight trajectory in high-performance interceptive sports where the ball is projected by the hand towards an opponent. Studies that reported the kinematics or ball flight characteristics of these movements were searched for using SportsDiscus, Scopus, MEDLINE and CINAHL Plus databases up to 27 April 2021. Forty-eight articles met the inclusion criteria, including 19 baseball, 12 cricket, five handball, four softball, three volleyball and five water polo studies. Extracted data were presented as ranges and descriptively analysed to report athlete sporting actions. Trajectory deviation can be caused by imparting an altered seam orientation or spin rate and axis of rotation on the ball. Athletes impart sidespin or manipulate seam orientation to cause lateral deviation while topspin and backspin are used to create vertical changes in the flight path. Adjusting the shoulder, forearm, wrist, hand and fingers of the throwing or striking arm can be used to impart an altered seam orientation or spin rate and axis of rotation on the ball. The findings of this review could assist coaches and athletes across a variety of sports to improve the ability to deviate the ball during flight.

Effect of weld seam orientation and welding process on fatigue fracture behaviors of HSLA steel weld joints

Welded steel structures can be exposed to high dynamic forces and failure typically occurring at the weakest zone within a few (less than 102) cycles. In order to investigate low-cycle fatigue fracture in weld joints of high-strength low-alloy (HSLA) steels, we have studied the fatigue properties in different weld seam orientations and welding processes. The fatigue performance showed that with transverse welding, fatigue lives at high strains (2%) were approximately seven times higher than with diagonal welding, and, for laser welded seams, fatigue lives were approximately two times higher than those for the plasma arc welded seams.

Effects of leakage rate and liner seam orientation on detection monitoring configurations at waste impoundments

A modeling study examined the effect of leakage rate and liner seam orientation on configurations of contaminant detection wells in groundwater. Monitoring networks took into account the unknown lo...

Automatic seam pucker evaluation using support vector machine classifiers

PurposeThe purpose of this paper is to propose a novel method using support vector machine (SVM) classifiers for objective seam pucker evaluation. Features are extracted using wavelet analysis and gray-level co-occurrence matrix (GLCM), and the samples are evaluated using SVM classifiers. The study aims to solve the problem of inappropriate parameters and large required samples in objective seam pucker evaluation.Design/methodology/approachInitially, seam pucker image was captured, and Edge detection and Hough transform were utilized to normalize the seam position and orientation. After cropping the image, the intensity was adjusted to the same identical level through histogram specification. Then, the standard deviations of the horizontal image and diagonal image, reconstructed using wavelet decomposition and reconstruction, were calculated based on parameter optimization. Meanwhile, GLCM was extracted from the restructured horizontal detail image, then the contrast and correlation of GLCM were calculated. Finally, these four features were imported to SVM classifiers based on genetic algorithm for evaluation.FindingsThe four extracted features reflected linear relationships among five grades. The experimental results showed that the classification accuracy was 96 percent, which catches up to the performance of human vision, and resolves ambiguity and subjective of the manual evaluation.Originality/valueThere are large required samples in current research. This paper provides a novel method using finite samples, and the parameters of the methods were discussed for parameter optimization. The evaluation results can provide references for analyzing the reason of wrinkles during garment manufacturing.

Drag and lift measurements of solid sports balls in still air

The following article considers lift and drag measurements of solid sports balls propelled through still air in a laboratory setting. The balls traveled at speeds ranging from 26 to 134 m/s with spin rates up to 3900 r/min. Light gates measured the speed and location of the balls at two locations from which lift and drag values were determined. Ball roughness varied from polished to rough surface protrusions, that is, seams as high as 1.5 mm. Lift and drag were observed to depend on speed, spin rate, surface roughness, and seam orientation. A drag crisis was observed on smooth balls as well as non-rotating seamed balls with seam heights less than 0.9 mm. The drag coefficient of approximately 0.42 was nearly constant with speed for spinning seamed balls with seam height greater than 0.9 mm. The still air drag coefficient of smooth balls was comparable to wind tunnel drag at low speeds ( Re &lt; 2 × 105) and higher than wind tunnel results at high speeds ( Re &gt; 2 × 105). The lift and drag coefficients of spinning balls increased with increasing spin rate. The lift coefficient of baseballs was not sensitive to ball orientation or seam height.

Relation Between Lift Force and Ball Spin for Different Baseball Pitches.

Although the lift force (F(L)) on a spinning baseball has been analyzed in previous studies, no study has analyzed such forces over a wide variety of spins. The purpose of this study was to describe the relationship between F(L) and spin for different types of pitches thrown by collegiate pitchers. Four high-speed video cameras were used to record flight trajectory and spin for 7 types of pitches. A total of 75 pitches were analyzed. The linear kinematics of the ball was determined at 0.008-s intervals during the flight, and the resultant fluid force acting on the ball was calculated with an inverse dynamics approach. The initial angular velocity of the ball was determined using a custom-made apparatus. Equations were derived to estimate the F(L) using the effective spin parameter (ESp), which is a spin parameter calculated using a component of angular velocity of the ball with the exception of the gyro-component. The results indicate that F(L) could be accurately explained from ESp and also that seam orientation (4-seam or 2-seam) did not produce a uniform effect on estimating F(L) from ESp.

Ball flight kinematics, release variability and in‐season performance in elite baseball pitching

The purpose of this study was to quantify ball flight kinematics (ball speed, spin rate, spin axis orientation, seam orientation) and release location variability in the four most common pitch types in baseball and relate them to in-season pitching performance. Nine NCAA Division I pitchers threw four pitching variations (fastball, changeup, curveball, and slider) while a radar gun measured ball speed and a 600-Hz video camera recorded the ball trajectory. Marks on the ball were digitized to measure ball flight kinematics and release location. Ball speed was highest in the fastball, though spin rate was similar in the fastball and breaking pitches. Two distinct spin axis orientations were noted: one characterizing the fastball and changeup, and another, the curveball and slider. The horizontal release location was significantly more variable than the vertical release location. In-season pitching success was not correlated to any of the measured variables. These findings are instructive for inferring appropriate hand mechanics and spin types in each of the four pitches. Coaches should also be aware that ball flight kinematics might not directly relate to pitching success at the collegiate level. Therefore, talent identification and pitching evaluations should encompass other (e.g., cognitive, psychological, and physiological) factors.

An Experimental Study of Baseballs and Softballs

The primary aim of this study is to experimentally evaluate the effects of seam orientation and angle of attack on aerodynamic drag for a series of commercially manufactured baseballs and softballs used in major tournaments. The aerodynamic forces and moments were measured experimentally over a range of wind speeds and angles of attack at different seam orientations with respect to the wind direction. The results indicate that the seam orientation had profound impact on aerodynamic characteristics of both baseball and softball. The average CD variation between sides of baseball facing the wind can vary up to 16%. The results also indicate an increase of CD values with the increase of angle of attack for all balls and seam positions tested.

A study of baseball and softball aerodynamics

Baseball and softball are popular sports in many parts of the world especially in North America. These games are enjoyed both by participants and spectators. The flight trajectory of a baseball and softball largely depends on their aerodynamic characteristics. Despite the popularity of the game, it appears that little information on the aerodynamic force experienced by a baseball and softball is available. Having curved stitches, complex seams and their orientation, the airflow around these balls are believed to be significantly complex and little understood. The primary objective of this study was to measure aerodynamic drag of a series of baseballs and softballs. The aerodynamic forces and moments were measured experimentally for a range of wind speeds and seam orientations. The aerodynamic forces and their non-dimensional coefficients were analysed. The results indicate that the drag coefficients of a baseball and softball did not undergo a distinctive drag crisis as a smooth sphere due to their complex seams and their orientation. The findings also indicate that the seam orientation had profound impact on aerodynamic characteristics of both balls.

Effects of seam and surface texture on tennis balls aerodynamics

Currently, serving becomes a dominant factor in tennis tournament as the ball travels faster and sometimes the returning player and spectators are unable to follow the track of the ball. As a result, the game becomes boring causing the spectator to lose passion for the game. The reduced speed of the ball can make the game more enjoyable. The understanding of aerodynamic behaviour of tennis balls is important in helping to design and develop a ball that can slow down the game. The complex surface texture of a tennis ball may affect its aerodynamic behaviour as well. As limited information on aerodynamic behaviour of contemporary tennis balls are available, a study was undertaken to investigate the effects of seam and surface texture of a range of commercially manufactured tennis balls. The drag coefficients were analysed and compared. The surface texture and seam orientation showed a noticeable variation in drag coefficients among these balls.

Experimental analysis of airbag seam design: high-rate shear testing for skin abrasions

Approximately 66 per cent of all airbag deployments in the USA result in at least one skin injury, with 47 per cent of these skin injuries attributed directly to the airbag deployment. The purpose of the present study was to evaluate the risk of skin abrasions from the airbag fabric seam design by using a new shear testing methodology. High-rate shear loading was performed with a pneumatic impactor that propelled a section of airbag fabric across porcine skin at 85 m/s. Twenty-seven tests (three control and 24 with fabric) were performed using eight different seam designs. A 40 cm × 10 cm section of airbag fabric with each seam was forced across a 5 cm × 5 cm section of fresh porcine skin that was acquired within 2 h post-mortem. No abrasions were observed in the three control tests, but abrasions were observed in all 24 of the tests conducted using airbag fabric. The unturned, sewn seam orientation resulted in significantly more severe abrasions than the woven, unturned seam orientation ( P = 0.01). This new system and results illustrate that different seam designs can result in different skin abrasion risk. Moreover, the data show that severe abrasions can be caused by normal pressures well below the 1.75 MPa injury threshold previously published.

Comparative aerodynamic analysis of commercial swimsuits

The primary objective of this research is to investigate and describe the effects of swimsuits' surface profile and seam orientations on aerodynamic drag. Two commercial swimsuits (Speedo LZR and TYR Sayonara) materials were evaluated in a wind tunnel environment using a standard cylindrical experimental arrangement. The effects of swimsuit surface profile and seam orientations on aerodynamic drag were evaluated for a range of Reynolds numbers. The measured drag forces were converted to dimensionless drag coefficients, which were compared for both swimsuits under different conditions. The results show that the material surface structure (roughness and seam orientations) of the swimsuit has significant effect on aerodynamic drag. The seam orientation at 45° has the potential to reduce the drag by around 15% depending on the seam geometry (i.e., seam height, width, etc.) and Reynolds number. The TYR Sayonara swimsuit can provide aerodynamic advantage at low Reynolds number (e.g. below Re = 1.63 × 105) due t...

Study on Throw Accuracy for Baseball Pitching Machine with Roller (Study of Seam of Ball and Roller)

The most common commercial pitching machines for baseball are the “roller” type and the “arm” type. Pitches such as the fastball, curveball and screwball are easily achieved by the pitching machine with three rollers which were developed by the authors. In this study, the moving behavior and contact stress state of the ball pitched with the three rollers type pitching machine is analyzed using dynamic finite element analysis software (ANSYS/LS-DYNA). The effect of a seam of a baseball to the throw accuracy is analyzed numerically. In the analysis, the finite element models of a detailed baseball with a seam and a pitching machine with three rollers are used. Additionally, the initial velocity and the spin rate of the pitched ball are filmed using a high-speed videograph, and those pictures are compared with the finite element analysis. From the analytical results, it is understood that the coefficient of friction between the baseball and the rollers is not affected. Additionally, it is obvious that the ball's velocity and spin rate are relatively unaffected by the seam orientation, while the throw's horizontal and vertical angles are notably affected by the relative angular velocity of the rollers and the orientation of the seam.