Shot Direction Research Articles

Determinant actions in men’s professional padel performance

ABSTRACT The main objective of the present research was to know the variables of the game in padel determining in the sport performance in men’s category in the season 2022–2023 in World Padel Tour. The independent variables considered in this study were: court side, laterality, stroke type, origin of the ball, net distance, shot direction and trajectory. The dependent variable was the effectiveness of the game actions. Four thousand five hundred and five game actions were analysed during the finals of the four masters (Marbella, Valladolid, Madrid, Buenos Aires) and the final master (Barcelona) of the 2022–2023 season of the World Padel Tour were analysed. The multinomial logistic regression applied showed that, the variables that predict the effectiveness of the game actions are: stroke type, net distance, shot direction and trajectory (level of statistical significance was p < .05). Specifically, our results show us that the stroke type that we must use to be more effective and score points is the smash, we must hit down the line, from areas close to the net and with a downward trajectory. These results show the characteristics of the game actions that determine the performance with the aim that they can help guide coaches in the training process of padel players.

Relationship between Ball Impact Point, Type of Stroke and Shot Direction in High-Performance Padel

This study aimed to analyze the relationship between ball impact point, type of stroke, and shot direction in high-performance padel. A total of 8363 strokes from nine matches of three national tournaments involving a total of 24 male players were subjected to systematic observation. The variables analyzed were type of stroke, shot direction, and ball impact. A descriptive analysis was conducted for each study variable, with a comparison of the variables performed using Pearson’s Chi-Square test, column proportions determined using a Z test according to Bonferroni (p &lt; 0.05), an association established by corrected standardized residuals, and an effect size calculated using Crammer’s V. The results showed that the most-used stroke types were volleys, serves, groundstrokes, and backwall shots (67.6%). The cross-court direction stood out over down-the-line and inside-out directions. Finally, almost two-thirds of the impact point locations were forward. In addition, the type of stroke determined shot direction and ball impact location. Moreover, the ball’s impact location significantly determined shot direction. In conclusion, these results suggest that the ball impact location and the type of stroke provide information from which padel shot direction can be anticipated. Such knowledge may constitute a very important factor affecting performance and success among padel players.

Is Anticipation Skill Learning Bayesian?

ABSTRACT Purpose: The aims of this study were to examine the learning of anticipation skill in the presence of kinematic and outcome probabilities information, and to see if this learning exhibited characteristics of Bayesian integration. Method: Participants with no competitive tennis playing experience watched tennis player stimuli playing forehand tennis shots and were tasked with predicted shot outcomes. Accuracy, response times and perceived task effort were recorded, pre, post and during four acquisition blocks where outcome feedback was provided. In both Experiment 1 and 2, kinematic information about shot direction was either present in the training group stimuli or absent. In Experiment 1, left/right shot probability information remained equi-probable for both groups. In Experiment 2, both groups also trained with a bias in the shot outcome probability toward one shot direction on 80% of the trials across acquisition blocks (and were not told about this manipulation). Results: Pre-to-post anticipation performance improved in the presence of kinematic (EXP 1) or both information sources (EXP 2). Pre-to-post improvements in the presence of shot outcome probability information were congruent with the bias in the shot direction trained (EXP 2). Superior anticipation performance was found when both information sources were present. The presence of kinematic information resulted in increased perceived effort during early training (EXP 1 & 2). Bayesian odds ratios indicated that shot direction probabilities and kinematic information were integrated during anticipation skill learning. Conclusion: Learning with shot direction probabilities and kinematic information shows characteristics of Bayesian integration.

THE PROJECTILE CALIBER AND TYPE DETERMINATION BY SUPERIMPOSITION ON THE EXIT CRANIAL VAULT DEFECT

A case of group identification of a firearm projectile using a comparative study by the overlay method is presented. Morphological characteristics of the exit gunshot bullet fractures are generally used to establish the direction and number of shots. Identification was carried out by exit gunshot injury to the bones of the skull vault of the skeletonized corpse. The shape and size of the gunshot perforated fracture displayed the caliber of the bullet and its lateral profile. Examination of the bone remains established a single penetrating gunshot bullet wound of the 1st cervical vertebra (atlas) and the skull. In this case the entry injury, located on the anterior arch of the atlas and the basilar part of the occipital bone, did not have identification significance. Peer Review History: Received: 22 October 2023; Revised: 23 November; Accepted: 29 December, Available online: 15 January 2024 Academic Editor: Dr. Jennifer Audu-Peter, University of Jos, Nigeria, drambia44@gmail.com Received file: Reviewer's Comments: Average Peer review marks at initial stage: 6.0/10 Average Peer review marks at publication stage: 7.5/10 Reviewers: Prof. Hassan A.H. Al-Shamahy, Sana'a University, Yemen, shmahe@yemen.net.ye Dr. Rima Benatoui,Laboratory of Applied Neuroendocrinology, Department of Biology, Faculty of Science, Badji Mokhtar University Annaba, Algeria. benattouiryma@gmail.com Dr. Asia Selman Abdullah, University of Basrah, Iraq, asia_abdullah65@yahoo.com

Pseudo-3D Receiver Deghosting of Seismic Streamer Data Based on l1 Norm Sparse Inversion

The ghost effect in marine seismic data causes low-frequency suppression and frequency notch, resulting in incomplete frequency information for seismic records, which poses challenges for high-resolution imaging. The deghosting effect depends on the approximation of the ghost delay operator. Due to the strict requirements of dense sampling, the 2D deghosting method for a densely sampled inline dataset is still the mainstream method for marine data processing. As the trade-off, inversion-based methods are widely used in the industry to reduce the influence of the inaccurate ghost delay operator. In order to overcome the sampling limits and improve the 2D deghosting effect, we propose a pseudo-3D deghosting framework based on an l1 norm sparse inversion. In the framework, the inversion problem is divided into two subproblems, i.e., pseudo-3D operator building and optimization inversion. Considering the data coherence along the shot direction, we derive a pseudo-3D ghost delay operator to deghost simultaneously for multi-shot gathers. We then introduce a sparse inversion method in the pseudo-3D radon domain (multi-shot gathers) to further improve the inversion accuracy. The proposed framework is easy to implement, is not sensitive to noise, and shows superior performance in synthetic and field examples.

Prediction of the penalty kick direction in men’s soccer

ABSTRACT The penalty kick might be a crucial moment during a soccer game because of its relevance on the scoreboard, mainly during shootouts. For this purpose, the present study established a model to predict the ball direction taking into consideration the leg dominance of the penalty taker and other posture variables just before the ball contact. A total of 412 penalties from 11 international high-standard tournaments (2010–2019) were analysed. The better predictive model for the shot direction was selected through all possible subsets regression method. Thus, the final model included three predictors and two multiplicative terms, with an acceptable classifying power with a specificity and sensitivity greater than 85%. This model was applied for predicting the probability to shot to the left and the right side of the goal in 12 different kicking patterns. The most frequent pattern was a right-footed taker with the left arm in a >90° abduction with a left orientation of the support foot (n = 122; 30%). Following this pattern, probability of shooting to the left or to the right was 0.970 (95% CI: 0.927–0.988) and 0.030 (95% CI: 0.012–0.073), respectively. The present study conceived a model as parsimonious as possible with three predictors easily available to the goalkeeper.

Reduction of the occurrence of incorrect stunning and the occurrence of reflexes and reactions in cattle after pneumatically powered captive-bolt stunning in comparison with cartridge-fired captive-bolt stunning.

In this study, the occurrence of repeat stunning, deviations in placement and direction of stun shots, and the occurrence of reflexes/reactions following stunning with a pneumatically powered captive-bolt stunner in comparison with a cartridge-fired captive-bolt stunner in cattle were assessed. Repeat stunning and deviations in placement and direction of the stun shots were less frequent (p < 0.01) with the use of a pneumatic stunner in all cattle. The rate of repeat stunning and deviation from the ideal place and direction of stun shots were lower (5.81%, 24.75%, and 9.60% of all animals, respectively) when a pneumatic stunner was used in comparison with cartridge-fired captive bolt (18.32%, 34.03%, and 47.38% of all animals, respectively). The stunning quality was assessed on the basis of evaluation of signs observed following the stun shot. A pneumatic stunning resulted in a significant reduction of occurrence of signs particularly in bulls in comparison to cows, for which a cartridge-fired stunner already provides an adequate stunning. Our study provides evidence that pneumatic stunning has the potential to be a more effective method than cartridge-fired stunning from the viewpoint of the welfare of slaughtered animals. Pneumatic stunning ensures a high quality of stunning in both bulls and cows.

Computer assisted three-dimensional reconstruction of scene in firearm homicide.

Worldwide advances in computer techniques are not yet recognised in the practice of forensic medicine. A promising application is their use in making a three-dimensional reconstruction of the crime scene. This study analyses this technique in a homicide by firearm. Queries regarding the direction and number of shots, position of the victim inside the car when shot at and presence of the accused at the crime scene were answered by a scientific model. Similar reconstruction of the scene, nailing the accused in a heinous crime, has not previously been reported as a study or a case. The paper anticipates impetus to the growth of literature in criminology and forensic sciences. It will also expedite the delivery of justice based on scientific evidence in controversial causes of death.

Effects of shot peening on microstructure evolution and mechanical properties of surface nanocrystal layer on titanium matrix composite

Shot peening (SP) was employed to modify the surface microstructure and mechanical properties of (TiB+TiC)/Ti-6Al-4V titanium matrix composite (TMC). And the microstructure evolution and mechanical properties were characterized and analyzed in detail. Transmission electron microscopy (TEM) results illustrated that the surface nanograins were introduced by the effect of SP and the hindering of reinforcements to the matrix deformation. The nanograins were formed near the reinforcement/matrix interface because the matrix was squeezed by both the shots and the reinforcements. Moreover, with increasing the volume fraction of reinforcements, the smaller nanograins were introduced near the interfaces due to the severe deformation between the matrix and reinforcements, which were caused by the decrease in average distance between two reinforcements. Under the same intensity of SP, the deformation of TiC was more severe than that of TiB, and more dislocations were introduced around TiC. The results were influenced by both the different shapes and distribution of reinforcements, and the impact direction of shots. After SP, the compressive residual stress (CRS) and the hardness in the peened surface layer were improved, which was due to the surface deformation, nanograins and high dislocation density in the nanocrystal layer.

In-match penalty kick analysis of the 2009/10 to 2018/19 English Premier League competition

ABSTRACT The in match penalty kick may be a decisive event in a match, as well as an opportunity to progress in a knockout competition or ultimately the final standings of a competition. The aims of the current study were to conduct a video-based performance analysis of in-match penalty kicks in the English Premier League (EPL) between the 2009/10 and 2018/19 seasons to identify the relationship between selected situational (match location, match status and match period), technical (penalty taker’s footedness), and performance indicators (shot direction) and in-match penalty kick outcomes and directions. All the in-match penalty kicks (N = 952) that took place in the EPL were analysed using Nacsport video analysis software. In-match penalty kick direction, specifically vertical direction, significantly influenced in-match penalty kick outcomes (p < 0.01). Match period, score line, match location and footedness had no significant effect on in-match penalty kick outcomes or direction of the kick. The study revealed that in-match penalty kicks should be directed towards the top vertical zones of the goal area to optimise the opportunity for success of in-match penalty kicks. Importantly, the risk factor of aiming high and missing is lower than aiming low and being saved, as such; coaches and players should implement systematic penalty kick training programmes aimed at improving penalty kick placements and control into the top areas of the goal.

Prediction of action outcome: Effects of available information about body structure.

Correctly perceiving the movements of opponents is essential in everyday life as well as in many sports. Several studies have shown a better prediction performance for detailed stimuli compared to point-light displays (PLDs). However, it remains unclear whether differences in prediction performance result from explicit information about articulation or from information about body shape. We therefore presented three different types of stimuli (PLDs, stick figures, and skinned avatars) with different amounts of available information of soccer players' run-ups. Stimulus presentation was faded out at ball contact. Participants had to react to the perceived shot direction with a full-body movement. Results showed no differences for time to virtual ball contact between presentation modes. However, prediction performance was significantly better for avatars and stick figures compared to PLDs, but did not differ between avatars and stick figures, suggesting that explicit information about the articulation of the major joints is mainly relevant for better prediction performance, and plays a larger role than detailed information about body shape. We also tracked eye movements and found that gaze behavior for avatars differed from those for PLDs and stick figures, with no significant differences between PLDs and stick figures. This effect was due to more and longer fixations on the head when avatars were presented.

Physical Demand Comparisons between Cleco’s Low Torque Reaction and Bosch’s ERGOSTOP Right-Angle Power-Tool Fastening Strategies

The purpose of this work was to compare the physical demands associated with the right-angle power-tool (RAPT) operation when using Cleco’s Low Torque Reaction (LTR) and Bosch’s ERGOSTOP fastening strategies during simulated tightening of various joints. Twenty healthy participants (N=10 M, N=10 F, 21.1 ± 0.3 years) having no RAPT experience and no injuries to the arms or trunk participated in the study, however, 8 participants data were not analyzed due to equipment malfunction. Participants completed a five-minute bout of 5 joint fastening per minute for every experimental condition. Participant’s completed twelve total conditions including: 3 target torques (30, 55 and 75 Nm); 2 tightening strategies (Cleco’s Low Torque Reaction and Bosch’s ERGOSTOP); 2 joint hardness (Hard, which target torque was achieved at 30° of spindle rotation; Soft, which target torque was achieved at 520° of spindle rotation). All fastenings were completed with a common joint location-orientation of horizontal (53 cm), vertical (103 cm), lateral (35 cm) using a downward shot direction. Our data revealed that for all conditions (Target Torque, Joint Type &amp; Tightening Strategy), Cleco’s LTR strategy resulted in lower physical demands. This is based on LTR fastenings resulting in lower push/pull magnitudes force impulse, peak forces and pulse-width times. From an ergonomics perspective, the reduction of physical force demand is a primary element of reducing the risk of work-related-musculoskeletal-disorders, the outcomes from this work was designed to aid ergonomists/engineers in understanding the physical demand magnitudes of RAPT operations in an effort to optimize manufacturing operations.

Information Accrual From the Period Preceding Racket-Ball Contact for Tennis Ground Strokes: Inferences From Stochastic Masking.

Previous research suggests the existence of an expert anticipatory advantage, whereby skilled sportspeople are able to predict an upcoming action by utilizing cues contained in their opponent’s body kinematics. This ability is often inferred from “occlusion” experiments: information is systematically removed from first-person videos of an opponent, for example, by stopping a tennis video at the point of racket-ball contact, yet performance, such as discrimination of shot direction, remains above chance. In this study, we assessed the expert anticipatory advantage for tennis ground strokes via a modified approach, known as “bubbles,” in which information is randomly removed from videos in each trial. The bubbles profile is then weighted by trial outcome (i.e., a correct vs. incorrect discrimination) and combined across trials into a classification array, revealing the potential cues informing the decision. In two experiments (both with N = 34 skilled tennis players) we utilized either temporal or spatial bubbles, applying them to videos running from 0.8 to 0 s before the point of racket-ball contact (cf. Jalali et al., 2018). Results from the spatial experiment were somewhat suggestive of accrual from the torso region of the body, but were not compelling. Results from the temporal experiment, on the other hand, were clear: information was accrued mainly during the period immediately prior to racket-ball contact. This result is broadly consistent with prior work using nonstochastic approaches to video manipulation, and cannot be an artifact of temporal smear from information accrued after racket-ball contact, because no such information was present.

Contextual cue utilization in visual anticipation in tennis: On the role of an opponent’s on-court position and skill

In batting and racket sports, players rely on kinematic and contextual cues to anticipate an opponent’s action outcome. In tennis, an opponent’s on-court position has been found to be a contextual cue signaling stroke direction. Additionally, given the varying technical–tactical repertoire associated with an opponent’s skill, the latter may further influence prediction behavior. Here, we sought to replicate position dependency in visual anticipation and to test the hypothesized interaction between an opponent’s on-court position and skill upon stroke direction anticipation in tennis. To this end, skilled tennis players predicted shot direction of point-light animated forehand groundstrokes that were executed at different on-court positions and occluded at three different time points. In block 1, no skill information was given, whereas in blocks 2 and 3 participants were told to either face opponents from the Bundesliga or Kreisliga. In line with former evidence, shot outcome predictions varied as a function of an opponent’s on-court position. Also, participants’ reliance on position information was strongest when little kinematic information was available. However, knowledge of an opponent’s purported skill was not found to reliably affect prediction behavior. By contrast, post-experiment questionnaire data suggest that players explicitly assign different shot direction probabilities depending on an opponent’s skill and position. Collectively, our research supports especially the role of on-court position for tennis stroke outcome anticipation. The conflicting findings on the potential role of knowledge of an opponent’s skill call for further empirical verification.

Behavior of a Railgun Launch Package at the Muzzle and During Sabot Discard

Projectiles launched with ISL’s PEGASUS railgun achieve muzzle velocities well beyond 2000 m/s. The design of the corresponding 1.3-kg launch package of caliber $40\times 40$ mm2 was presented at the 18th EML-Symposium in 2016. Meanwhile, the phase after muzzle exit has been studied, and in particular, the sabot separation in the air flow has been investigated. To that end, a numerical model was used which had been previously validated by means of shock tunnel experiments. Besides the subprojectile, the launch-package essentially consists of the armature, on which the Lorentz force is acting, and further, of two sabot parts with integrated bore riders. The numerical model describes the launch-package flight in moving coordinates in the shot axis direction, i.e., the package is considered to be initially fixed in space, surrounded by a constant velocity air flow. The launch package components are able to move and to deform in the three dimensions thereafter. It is further possible to introduce lateral perturbation, e.g., linear and angular motion due to the muzzle disturbance. Although the airflow is modeled with a Eulerian code neglecting viscous effects, the computation results agree very well with the experiments. Hereby, it is demonstrated that the numerical model can effectively be used as a tool for launch package design optimization. An example is given for a fin-stabilized projectile which shall be launched with the new 6-m-long NGL60 railgun having a bore cross section of $60\times 60$ mm2.

Falling for a Fake: The Role of Kinematic and Non-kinematic Information in Deception Detection.

Kinematic and non-kinematic visual information have been examined in the context of movement anticipation by athletes, although less so in deception detection. This study examined the role of kinematic and non-kinematic visual information in the anticipation of deceptive and non-deceptive badminton shots. Skilled ( n = 12) and less skilled ( n = 12) badminton players anticipated the direction of deceptive and non-deceptive shots presented via video footage displayed in normal (kinematic and non-kinematic information), low (kinematic information emphasized), and high (non-kinematic information emphasized) spatial frequency conditions. Each shot was occluded one frame before shuttle-racquet contact or at contact. In deceptive trials, skilled players showed decreased anticipation accuracy in the high spatial frequency condition ( p = .050) compared to normal and low spatial frequency conditions, which did not differ. The study suggests that an emphasis on kinematic information results in accurate anticipation in response to deceptive movements and that an emphasis on non-kinematic information results in less accurate anticipation by experts.

Classification Videos Reveal the Visual Information Driving Complex Real-World Speeded Decisions.

Humans can rapidly discriminate complex scenarios as they unfold in real time, for example during law enforcement or, more prosaically, driving and sport. Such decision-making improves with experience, as new sources of information are exploited. For example, sports experts are able to predict the outcome of their opponent's next action (e.g., a tennis stroke) based on kinematic cues “read” from preparatory body movements. Here, we explore the use of psychophysical classification-image techniques to reveal how participants interpret complex scenarios. We used sport as a test case, filming tennis players serving and hitting ground strokes, each with two possible directions. These videos were presented to novices and club-level amateurs, running from 0.8 s before to 0.2 s after racquet-ball contact. During practice, participants anticipated shot direction under a time limit targeting 90% accuracy. Participants then viewed videos through Gaussian windows (“bubbles”) placed at random in the temporal, spatial or spatiotemporal domains. Comparing bubbles from correct and incorrect trials revealed how information from different regions contributed toward a correct response. Temporally, only later frames of the videos supported accurate responding (from ~0.05 s before ball contact to 0.1 s afterwards). Spatially, information was accrued from the ball's trajectory and from the opponent's head. Spatiotemporal bubbles again highlighted ball trajectory information, but seemed susceptible to an attentional cuing artifact, which may caution against their wider use. Overall, bubbles proved effective in revealing regions of information accrual, and could thus be applied to help understand choice behavior in a range of ecologically valid situations.

Can Slow-Motion Footage of Forehand Strokes Be Used to Immediately Improve Anticipatory Judgments in Tennis?

Slow-motion footage of sports actions is widely used as a visual learning tool in observing the dynamic motor behaviors of athletes. Recent studies on action observation have reported that extending the observation time in slow-motion footage provides benefits of understanding the intention of an opponent’s action, at least when observing rapid movements. As such, the use of slow-motion footage may have the potential to improve the anticipatory judgments of an opponent’s action outcome without training (or feedback). To verify this possibility, we examined the effects of the replay speed of slow-motion footage on the anticipatory judgments of shot directions and recognition of kinematic positions of opponents’ forehand strokes in tennis. Nine skilled and nine novice tennis players were asked to anticipate the direction of their opponent’s shots (left or right) and then attempted to recognize proximal (trunk center) and distal (ball) kinematic positions. Computer graphic animations of forehand strokes were used as visual stimuli, which were presented at four different replay speeds (normal, three-quarter, half, and quarter speeds). We failed to show the immediate effect of the use of slow-motion footage on the anticipatory performance of the skilled and novice players, although the anticipatory performance of the skilled players was superior to that of the novice players. Instead, we found an effect of the use of slow-motion footage in terms of promoting recognition of important kinematic cues (trunk center) for effective anticipation by skilled players. Moreover, no significant correlations were observed between the anticipatory judgments and motion recognition in all experimental conditions. These results suggest that even if the use of slow-motion footage enhances the recognition of key kinematic cues, it may not immediately improve anticipatory judgments in tennis.

Anticipating the Direction of Soccer Penalty Shots Depends on the Speed and Technique of the Kick.

To succeed at a sport, athletes must manage the biomechanical trade-offs that constrain their performance. Here, we investigate a previously unknown trade-off in soccer: how the speed of a kick makes the outcome more predictable to an opponent. For this analysis, we focused on penalty kicks to build on previous models of factors that influence scoring. More than 700 participants completed an online survey, watching videos of penalty shots from the perspective of a goalkeeper. Participants (ranging in soccer playing experience from never played to professional) watched 60 penalty kicks, each of which was occluded at a particular moment (−0.4 s to 0.0 s) before the kicker contacted the ball. For each kick, participants had to predict shot direction toward the goal (left or right). As expected, predictions became more accurate as time of occlusion approached ball contact. However, the effect of occlusion was more pronounced when players kicked with the side of the foot than when they kicked with the top of the foot (instep). For side-foot kicks, the direction of shots was predicted more accurately for faster kicks, especially when a large portion of the kicker’s approach was presented. Given the trade-off between kicking speed and directional predictability, a penalty kicker might benefit from kicking below their maximal speed.

The role of contextual information during skilled anticipation.

In dynamic, temporally constrained tasks, individuals often need to anticipate what will happen next prior to information becoming available within the environment. In such situations, the availability of contextual information can facilitate anticipation, often in conjunction with postural information. While many researchers have identified the specific sources of postural information facilitating anticipation, few have investigated the specific sources of contextual information employed. In two experiments, we presented skilled and less-skilled tennis players with animations of rallies from real matches that omitted access to postural information from the opponent, constraining participants to anticipate based on contextual information alone. In Experiment 1, participants anticipated the outcome of an opponent's shot under three conditions in which the sequence length (i.e., number of shots in a rally) preceding the same occluded shot was varied. Participants anticipated shot direction more accurately when the preceding shot sequence was presented than not. In Experiment 2, we presented animations that depicted the ball, the players, or both, in either dynamic or still form. Those conditions in which only the ball was depicted yielded the lowest response accuracy scores. It appears that information from the player and ball motion is required to provide the context under which skilled performers can consciously pick up and utilise information to anticipate more accurately than their less-skilled counterparts.