Table Tennis Ball Research Articles

A Fatal Case of Whistle Blow in a Child

Death due to choking is observed in all age group but small children below 4 years of age are the common victims. Choking is commonly seen in children when objects such as small toys, table tennis ball and coins are placed in mouth or inhaled. Children younger than 1 year of age are more likely to aspirate food; whereas older children tend to choke on non-food items. We hereby report a case of death due to choking which was brought to the mortuary of SCB Medical College, Cuttack for autopsy. A 7yr old male child of southern part of Odisha sent for autopsy to the medical college with a history of an impacted foreign body (whistle) in the respiratory tract. The deceased accidentally swallowed the whistle 2 days back and after proper investigation failed to remove it by the local doctors. Then he died on the way to our medical college for treatment. On autopsy the place of sticking of the whistle within the larynx was noticed. The autopsy findings along with its treatment aspect are discussed in the paper.

Sudden Deaths Due to Choking

Death due to accidental choking is observed in all age group and small children below 4 years of age are the common victims. Choking is commonly seen in children when objects such as small toys, table tennis ball and coins are placed in mouth and inhaled. Food is the most common cause of choking and food which is the life provider can become an asphyxiating agent at times. Children younger than one year of age are more likely to aspirate food, whereas older children tend to choke on non-food items. Aspiration of gastric contents is common in individuals with a decreased level of consciousness in drug overdose and during anaesthesia. The risk of aspiration is high after removal of an endotracheal tube because of residual effects of sedative drugs, the presence of a nasogastric tube, swallowing dysfunction related to upper airway sensitivity, glottic injury and laryngeal muscular dysfunction. Aspiration can present with acute respiratory distress but in many elderly individuals, it is silent. We hereby report cases of sudden death due to choking which were brought to our mortuary for autopsy.

B-18 飛翔中の卓球ボール周りのPIV(飛翔特性ほか)

It is said that there are some differences between wind tunnel test and flight test on the ball aero dynamics. The reason of the difference seems to come from an acceleration and deceleration or unsteady motion at the flight test. In order to confirm the differences, PIV measurements around a flying table tennis ball are conducted. The high speed camera which frame rate is 10,000, is used to capture the instantaneous motion around the flying ball. The imaging region is 210mm×210mm. A coordinate transformation to the ball fixed coordinate system well captured the wake motion of non-rotating and rotating ball. It is observed that at non-rotating condition, the averaged wake velocity field of the ball is symmetric. On the other hand at rotating condition, it is asymmetric. These observations quantitatively agree with the wind tunnel test.

Potato Size and Shape Detection Using Machine Vision

To reduce the error and faster classification by mechanizing in classifying the potato shape and size through machine vision using the extraction of characters procedure to identify the size, and using the shape detection procedure to identify the shape. Test results in potato size detection revealed 40/191 = 0.210mm/pixel as length scale or calibration factor (40/M) where 40 is the table tennis ball size (40mm) and 191 as image pixels table tennis (M); measurement results revealed that between the algorithm results and the manual measurements, the absolute error was <3mm, while the relative error rate was <4%; and the measurement results based on the ellipse axis length can accurately calculate the actual long axis and short axis of potato. Potato shape detection revealed the analysis of 228 images composed of 114 positive and 114 negatives side, only 2 have been incorrectly classified, mainly because the Extracted ratio (R) of the potato image of those two positive and negative images are near 0.67, respectively 0.671887, 0.661063, 0.667604, and 0.67193. The comparison to establish a calibration system method using both basic rectangle and ellipse R ratio methods to detect the potato size and shape, revealed that the basic rectangle method has better effect in the case of fixed place. Moreover, the ellipse axis method was observed to be more stable with an error rate of 7%. Therefore it is recommended that the ellipse axis method should be used to detect the shape of potato for differentiation into round, long cylindrical, and oval shapes, with the accuracy level of 98.8%.

Design and Research of a Robotic Aided System for Retinal Vascular Bypass Surgery

With reference to the study of the robotic system for ophthalmology microsurgery, a robotic system was presented with the key mechanism design and control subsystem scheme considering the procedures and features of retinal vascular bypass surgery. After discussion of the clinical application, the human-machine cooperated surgical process of the robotic system for retinal vascular bypass surgery was described, and the design of the surgical layout environment was proposed. The intraocular motion planning method was also described and corresponding experiments using a table tennis ball model and an in vitro porcine eye model were performed. Finally, the feasibility analysis and robotic system error analysis were also summarized and future works discussed for further research.

Developing a Pollicization Outcomes Measure

To evaluate which objective criteria correlated with subjective impressions of outcome following index finger pollicization for thumb hypoplasia. Forty-two pollicizations in 35 patients were assessed by a comprehensive subjective and objective measurement analysis. In the subjective measures, the surgeon, therapist, and caregiver rated how the pollicized digit "looks like a thumb" and "works like a thumb." The caregiver also completed a subjective questionnaire. For objective results, we measured appearance, strength, range of motion, stability, and ability to pick up objects. The subjective results were then correlated with objective data via a linear regression analysis. When combining the total subjective score for "looks like a thumb," "works like a thumb," and the caregiver questionnaire, we found significant correlation scores for palmar abduction, lateral pinch, tip pinch, and picking up a bead, a die, and a table tennis ball. The strongest correlations were found with composite flexion, metacarpophalangeal (MCP) joint range of motion, interphalangeal (IP) joint range of motion, and the sticker test. Three of these 4 items (sticker test and MCP joint and IP arcs of motion) also correlated best with children who preferred using their thumbs for small object acquisition instead of scissor pinch. Composite flexion, MCP and IP joint arcs of motion, and the sticker test correlated the strongest with the subjective criteria. These parameters appear to be the most critical measures that impress a good outcome following pollicization. Prognostic IV.

Effect of four different reflective barriers on black-globe temperatures in calf hutches

Polyethylene hutches are a popular method of housing dairy calves from 0 to 60 or more days of age, although these hutches get hot when in full sun. This study characterized the relative differences in the ability of four different types of radiant barriers to reduce black-globe temperature within these hutches. Treatments included three different types of covers (two types of laminates (Cadpak P and Cadpak ESD) and an aluminized 3.0-mil white low-density polyethylene (LDPE)) and a reflective paint (LO/MIT-1). The reflective covers were 1.8 × 3 m finished size, and covered the top and sides of the hutch down to 0.15 m above the ground, leaving the front and back exposed. The LO/MIT-1 paint covered the entire sides and roof of the hutch. Two 24-h trials 1 week apart were conducted during relatively hot and clear days in early August. Black-globe temperatures were recorded in duplicate and averaged at 20-min intervals using blackened table tennis balls mounted 0.3 m above the floor in the center of each hutch. Ambient temperature (shade) during the hottest 2-h period for both trials averaged 39.9 °C while the uncovered control averaged 41.1 °C, and LO/MIT-1 averaged 39.9 °C; both of which were significantly higher (P < 0.01) than the Cadpak P (38.9 °C), Cadpak ESD (38.6 °C), and aluminized LDPE (38.7 °C). During periods of high solar radiation, the hutches with covers had lowest black-globe temperatures followed by hutches painted with reflective paint, while control hutches had the highest temperature.

Tissandier revisited—the answer

A famous 19th century experiment involved striking a rod balanced on two glasses. In my version (Featonby 2014 Phys. Educ. 49 120) a thin rod is placed horizontally between two supports about 80 cm apart. The supports consist of an uncooked egg in an egg cup. A table-tennis ball is placed on top the rod at each end. What happens next when the rod is given a sharp strike in the centre with another rod?

Does an Eye-Hand Coordination Test Have Added Value as Part of Talent Identification in Table Tennis? A Validity and Reproducibility Study

This study investigated the added value, i.e. discriminative and concurrent validity and reproducibility, of an eye-hand coordination test relevant to table tennis as part of talent identification. Forty-three table tennis players (7–12 years) from national (n = 13), regional (n = 11) and local training centres (n = 19) participated. During the eye-hand coordination test, children needed to throw a ball against a vertical positioned table tennis table with one hand and to catch the ball correctly with the other hand as frequently as possible in 30 seconds. Four different test versions were assessed varying the distance to the table (1 or 2 meter) and using a tennis or table tennis ball. ‘Within session’ reproducibility was estimated for the two attempts of the initial tests and ten youngsters were retested after 4 weeks to estimate ‘between sessions’ reproducibility. Validity analyses using age as covariate showed that players from the national and regional centres scored significantly higher than players from the local centre in all test versions (p<0.05). The tests at 1 meter demonstrated better discriminative ability than those at 2 meter. While all tests but one had a positive significant association with competition outcome, which were corrected for age influences, the version with a table tennis ball at 1 meter showed the highest association (r = 0.54; p = 0.001). Differences between the first and second attempts were comparable for all test versions (between −8 and +7 repetitions) with ICC's ranging from 0.72 to 0.87. The smallest differences were found for the test with a table tennis ball at 1 meter (between −3 and +3 repetitions). Best test version as part of talent identification appears to be the version with a table tennis ball at 1 meter regarding the psychometric characteristics evaluated. Longitudinal studies are necessary to evaluate the predictive value of this test.

B-28 卓球ボールの空力特性の風洞試験と飛翔試験の比較(ボールの空力特性)

B-28 卓球ボールの空力特性の風洞試験と飛翔試験の比較(ボールの空力特性)

Estimation of aerodynamic coefficients for a ball by using characteristics of trajectory

We investigate estimation methods of aerodynamic coefficients for a ball in sports by using characteristic quantities of its trajectory. One method is based on the quantities representing the whole shape of trajectory while the other utilizes local quantities such as curvature and/or torsion. In the former, the flight distance and the maximum height are measured, and the motion equation predicts numerical values of these quantities with measured initial conditions and preset aerodynamic coefficients. Then the optimal combination of the aerodynamic coefficients is determined by minimizing the error between the measured and estimated values of the characteristic quantities. This method is applied to estimate drag and lift coefficients of a soccer ball in back-spinning, and the result shows that the averaged values of CD and CL are 0.205 and 0.237, respectively. In the latter method, the expressions between the aerodynamic coefficients and the geometrical quantities of trajectory are derived, which suggests that the piecewise quadratic interpolation on a trajectory provides the aerodynamic coefficients. This method enables to locally estimate the coefficients, and therefore clarifies the variation of the coefficients along a trajectory. Measured data for a table tennis ball is analyzed with the method and we obtain successfully the drag and lift coefficients in flight condition. The results indicate the qualitative difference of spinning effect in drag and lift coefficients.

Haptic feedback enhances rhythmic motor control by reducing variability, not improving convergence rate

Stability and performance during rhythmic motor behaviors such as locomotion are critical for survival across taxa: falling down would bode well for neither cheetah nor gazelle. Little is known about how haptic feedback, particularly during discrete events such as the heel-strike event during walking, enhances rhythmic behavior. To determine the effect of haptic cues on rhythmic motor performance, we investigated a virtual paddle juggling behavior, analogous to bouncing a table tennis ball on a paddle. Here, we show that a force impulse to the hand at the moment of ball-paddle collision categorically improves performance over visual feedback alone, not by regulating the rate of convergence to steady state (e.g., via higher gain feedback or modifying the steady-state hand motion), but rather by reducing cycle-to-cycle variability. This suggests that the timing and state cues afforded by haptic feedback decrease the nervous system's uncertainty of the state of the ball to enable more accurate control but that the feedback gain itself is unaltered. This decrease in variability leads to a substantial increase in the mean first passage time, a measure of the long-term metastability of a stochastic dynamical system. Rhythmic tasks such as locomotion and juggling involve intermittent contact with the environment (i.e., hybrid transitions), and the timing of such transitions is generally easy to sense via haptic feedback. This timing information may improve metastability, equating to less frequent falls or other failures depending on the task.

Table Tennis: Preliminary Displacement in Pimples-Out Rubber

Following the recent trend of applying a more scientific approach to the study of all aspects of racket sports, we have developed a simple tribological method allowing to characterize unequivocally and unbiased by human factor the frictional behavior of table tennis rubber racket covering. This technique suggests examining the performance of rubber coverings at the onset of sliding against the table tennis ball by using three non-dimensional parameters, “friction,” “stickiness,” and “grip.” However, while “friction” and “stickiness” parameters were elaborated well, the “grip” parameter was only outlined due to the lack of actual determination of preliminary displacement on which it is based. To fill this gap, here we focus on studying preliminary displacement in four short and four long pimples-out rubbers. It is also found that a particular attention should be paid for the environmental conditions under which the three parameters are determined.

Effects of Different Ball Size and Ability on Table Tennis Backhand Block Learning

The purpose of this study was to examine the effects of different ball size and ability on table tennis backhand block learning and rate of progress in students. In this study, experimental group adopted the teaching method with 44 mm ball, while control group adopted the traditional teaching method with 40 mm ball. Both groups followed the same procedures of pre-test, experiment and post-test. The data were examined by the paired samples t-test, two-way ANCOVA and two-way ANOVA. The results were as follows: (1) The students' backhand block learning have significant improvement in addition to the higher ability students of the control group. (2) Comparing the ball size, the experimental group showed better backhand block learning skill than the control group. However, no significant differences were noticed on different abilities of students learning. For the rate of progress, the performance of students with lower ability is better than those with average ability, and the performance of students with average ability is better than those with higher ability in both experimental and control groups. In conclusion, students could effectively gain the skills of backhand block from the college table tennis classes by the teaching of tennis with 44 mm table tennis ball. This study suggested that it is a good teaching method in basic motor learning on table tennis backhand block with 44 mm ball to enhance the student's ability.

Racket Control for a Table Tennis Robot to Return a Ball

This paper mainly proposes a racket control method for returning a table tennis ball to a desired position with a desired rotational velocity. The method determines the racket's state, i.e., t...

Study of the dynamic properties and effects of temperature using a spring model for the bouncing ball

We studied the motion of a bouncing ball by representing it through an equivalent mass–spring system executing damped harmonic oscillations. We represented the elasticity of the system through the spring constant ‘k’ and the viscous damping effect, causing loss of energy, through damping constant ‘c’. By including these two factors we formed a differential equation for the equivalent mass–spring system of the bouncing ball. This equation was then solved to study the elastic and dynamic properties of its motion by expressing them in terms of experimentally measurable physical quantities such as contact time, coefficient of restitution, etc. We used our analysis for different types of ball material: rubber (lawn-tennis ball, super ball, soccer ball and squash ball) and plastic (table-tennis ball) at room temperature. Since the effect of temperature on the bounce of a squash ball is significant, we studied the temperature dependence of its elastic properties. The experiments were performed using audio and surface-temperature sensors interfaced with a computer through a USB port. The work presented here is suitable for undergraduate laboratories. It particularly emphasizes the use of computer interfacing for conducting conventional physics experiments.

235 卓球ボールにおける負のマグヌスカの測定(飛翔ボールの空力特性)

235 卓球ボールにおける負のマグヌスカの測定(飛翔ボールの空力特性)

パフォーマンス分析への応用を目的とした卓球ボールの3次元軌跡復元システム

In this paper, a method to reconstruct 3D trajectory of a table tennis ball and two systems that obtain shot information for table tennis performance analysis are proposed. The method and the systems are developed to solve the problem of conventional performance analysis in table tennis. There are several methods to reconstruct 2D ball trajectory or 3D trajectory of the heavy ball compares to a table tennis ball. However, the methods cannot be adopted for 3D trajectory reconstruction of a table tennis ball, because there are problems attribute to the dimension of a trajectory and the weight of a ball. The proposed method in this paper can reconstruct 3D trajectory of a table tennis ball. The key feature of the method is to approximate that a ball travels on tilted planes. The approximation makes the reconstruction robust against failure to measure 3D ball positions in some frames. Based on the proposed method, a system using two RGB cameras is developed. The system is experimentally verified that it can provide accurate information for match analysis. Next, a system using an RGB-D camera is developed to optimize usability for practitioners. The system is experimentally verified that it can provide accurate information for service analysis.

Gerbode ventricular septum defect covered by a ballooning membranous ventricular septum

A 55-year-old man was admitted due to a new cardiac murmur diagnosed by his general practitioner during check-up. The patient was asymptomatic and denied chest pain or dyspnea. Physical examination revealed a grade 3/6 holosystolic heart murmur at the left sternal border with increased intensity to handgrip maneuvers. In addition, mild edema was present at his ankles up to mid of the lower legs that the patient himself had not recognized before. Electrocardiogram, blood sample, and cardiac markers were unremarkable. Transthoracic echocardiography (TTE) revealed enlargement of heart chambers with normal systolic ventricular function and elevated pulmonary pressure. In addition, a cystic thin walled structure was seen with adhesion at the septal tricuspid valve ring that yo-yoed between the right atrium (RA) and the right ventricle (RV) like a table tennis ball. Colour Doppler echocardiography showed a complete systolic filling of this structure. Diagnostic work-up revealed a congenital defect of subaortic perimembranous ventricle septum (VSD) with conjunction between left ventricle (LV) and RA, a so-called Gerbode-VSD, covered by a prolapsing cystic formation of 38 9 29 9 27 mm (Figs. 1, 2). By MRI and heart catheterization, a relevant left-to-right shunt of 1:2 was measured. Hemodynamic parameters are given in Table 1. MRI confirmed a perforation of the cystic sack causing the shunt with direct flow to RA (Fig. 2b). Surgery under cardiopulmonary bypass was undertaken and revealed a right sided whitish cystic mass typical for a large diverticulum of the membranous ventricular septum with basis above the tricuspid valve and riding above a Gerbode-VSD of 6 mm. Opposite to the VSD, the cystic structure was perforated resulting in a direct communication between LV and RA (Figs. 2b and 3a, b). The diverticulum was removed, VSD was closed with a bovine pericardial patch and the tricuspid valve was successfully reconstructed. Pathohistologic inspection of the cystic structure showed endoand myocardium with fibrotic and sclerotic conversion and only mild chronic inflammatory reaction (Fig. 3c). Patient was discharged in stable conditions 10 days after surgery. The specific feature of our patient is the coverage of the Gerbode-VSD by the expanded membranous ventricular septum protruding into the RA with extension through the tricuspid valve during heart cycle. A small rupture of the cystic formation caused a nearly indirect shunt between LV and RA. Shunts between LV and RA are rare forms of VSD and can be either congenital or acquired. They were first described in 1857 and represent \1 % of all congenital cardiac defects [1]. The surgeon Frank Gerbode at Stanford had published the first successful series of patients operated on a LV–RA shunt in 1958 [2]. Acquired defects can occur secondarily after bacterial endocarditis, trauma, myocardial infarction, repair or replacement of either the mitral or aortic valves or are reported after catheter ablation of the atrioventricular node [1, 3–7] and are diagnosed using varying U. M. Muller (&) U. Pittl G. C. Schuler Department of Internal Medicine/Cardiology, Heart Center, University of Leipzig, Strumpellstrase 39, 04289 Leipzig, Germany e-mail: ulrike.mueller@herzzentrum-leipzig.de

The Influence of Visual Information on the Motor Control of Table Tennis Strokes

Theories of social interaction (i.e., common coding theory) suggest that visual information about the interaction partner is critical for successful interpersonal action coordination. Seeing the interaction partner allows an observer to understand and predict the interaction partner's behavior. However, it is unknown which of the many sources of visual information about an interaction partner (e.g., body, end effectors, and/or interaction objects) are used for action understanding and thus for the control of movements in response to observed actions. We used a novel immersive virtual environment to investigate this further. Specifically, we asked participants to perform table tennis strokes in response to table tennis balls stroked by a virtual table tennis player. We tested the effect of the visibility of the ball, the paddle, and the body of the virtual player on task performance and movement kinematics. Task performance was measured as the minimum distance between the center of the paddle and the center of the ball (radial error). Movement kinematics was measured as variability in the paddle speed of repeatedly executed table tennis strokes (stroke speed variability). We found that radial error was reduced when the ball was visible compared to invisible. However, seeing the body and/or the racket of the virtual players only reduced radial error when the ball was invisible. There was no influence of seeing the ball on stroke speed variability. However, we found that stroke speed variability was reduced when either the body or the paddle of the virtual player was visible. Importantly, the differences in stroke speed variability were largest in the moment when the virtual player hit the ball. This suggests that seeing the virtual player's body or paddle was important for preparing the stroke response. These results demonstrate for the first time that the online control of arm movements is coupled with visual body information about an opponent.