Table Tennis Racket Research Articles

Seismic behavior of double-cell CFST columns with table tennis racket-shaped cross section

Multicell concrete-filled steel tube (CFST) columns with excellent mechanical performance have been used in super high-rise buildings in recent years. According to the requirements of a 265-m tall building, the double-cell CFST columns with an innovative cross section of table tennis racket were applied. Hence, six columns were designed according to the prototype columns and subjected to low-frequency cyclic loading. The impacts of different shear-span ratios (SSRs), axial load ratios (ALRs), and steel ratios on the seismic behavior were elaborated and clarified. The test results indicated that the seismic performance varied in different loading directions owing to the asymmetric cross section, and the columns performed better in the positive loading direction resulted from earlier and more sufficient confinement of the circular steel tube, which was also reflected by the measured strain development. With SSR deceasing from 2.5 to 1.7, earlier and more severe damage was recorded. The resisting capacity and stiffness were significantly improved at a cost of ductility loss. Increasing ALR from 0.2 to 0.4 brought about more damage and worse deformability. However, a proper increase in axial load was beneficial to the resisting capacity and stiffness, and its influence on the restoration capacity was associated with SSR. Increasing the steel ratio (by 33.36%) could effectively postpone and alleviate the local buckling of steel tube, thereby comprehensively improving the seismic performance. A finite element (FE) analysis of such columns was performed to carry out the damage evolution and parametric study, and provide references for their application in practical engineering.

Elite male table tennis matches diagnosis using SHAP and a hybrid LSTM–BPNN algorithm

This study adopts a new approach, SHapley Additive exPlanation (SHAP), to diagnose the table tennis matches based on a hybrid algorithm, namely Long Short-Term Memory–Back Propagation Neural Network (LSTM–BPNN). 100 male singles competitions (8535 rallies) from 2019 to 2022 are analyzed by a hybrid technical–tactical analysis theory, which hybridizes the double three-phase and four-phase evaluation theories. A k-means cluster analysis is conducted to classify 59 players’ winning rates into three levels (high, medium, and low). The results show that LSTM–BPNN has excellent performance (MSE = 0.000355, MAE = 0.014237, RMSE = 0.018853, and {mathrm{R}}^{2} = 0.988311) compared with six typical artificial intelligence algorithms. Using LSTM–BPNN to calculate the SHAP value of each feature, the global results find that the receive-attack and serve-attack phases of the ending match have essential impacts on the mutual winning probabilities. Finally, case applications show that the SHAP can directly obtain each feature importance on one or more matches, which is more objective and reliable than the traditional simulation method. This research explores an innovative way to understand and analyze matches, and these results have implications for the performance analysis of table tennis and related racket sports.

Web-Based Communication of Wooden Sport Equipment: An Analysis Based on Six Olympic Sports

Wood has traditionally been used to make sports equipment and playing surfaces. While its use is outdated in several sports, in many others, wood remains well-established or even the material of choice, e.g., to make basketball floors or table tennis rackets. This study aims at evaluating the main drivers of web-based communication of wooden sport equipment. Six Olympic sports in which wood is still used were identified: baseball, skateboarding, skiing, snowboarding, surfboarding, and table tennis. For each sport, five websites of manufacturers were selected based on their page rank. Five evaluators assessed each website, rating the degree to which their discussion of wood intersected with four dimensions (and the related sub-dimensions): environment and ethics, design, wood technology, and communication. Significant differences (p < 0.05) are found among the dimensions, where communication and wood technology scored the higher ratings. Several differences are found among sub-dimensions, for instance in terms of attention given to environmental and social sustainability. Among the various findings, environmental and social sustainability, based on a proper commitment, is a relevant target for the web-based communication of manufacturers of wooden sport equipment. We argue that this is both for ethical reasons, and for market and image purposes.

First Characterization of a Hafnia Phage Reveals Extraordinarily Large Burst Size and Unusual Plaque Polymorphism.

A unique lytic phage infecting Hafnia paralvei was isolated and identified. Hafnia phage Ca belongs to the family Autographiviridae, possessing an icosahedral head with a diameter of 55 nm and a short non-contractile tail. Unusually, the burst size of Hafnia phage Ca of 10,292 ± 1,097 plaque-forming units (PFUs)/cell is much larger than other dsDNA phages reported before. Compared to the genome of the related phage, Hafnia phage Ca genome contains extra genes including DNA mimic ocr, dGTP triphosphohydrolase inhibitor, endonuclease, endonuclease VII, and HNH homing endonuclease gene. Extraordinarily, the phage developed different sizes of plaques when a single plaque was picked out and inoculated on a double-layer Luria broth agar plate with its host. Furthermore, varied packaging tightness for the tails of Hafnia phage Ca was observed (tail length: 4.35–45.92 nm). Most of the tails appeared to be like a cone with appendages, some were dot-like, bun-like, table tennis racket handle-like, and ponytail-like. Although the complete genome of Hafnia phage Ca is 40,286 bp, an incomplete genome with a deletion of a 397-bp fragment, containing one ORF predicted as HNH homing endonuclease gene (HEG), was also found by high throughput sequencing. Most of the genome of the virus particles in large plaques is complete (>98%), while most of the genome of the virus particles in small plaques is incomplete (>98%), and the abundance of both of them in medium-sized plaques is similar (complete, 40%; incomplete, 60%). In an experiment to see if the phage could be protective to brocade carps intramuscularly injected with H. paralvei LY-23 and phage Ca, the protection rate of Hafnia phage Ca to brocade carp (Cyprinus aka Koi) against H. paralvei was 33.38% (0.01 < p < 0.05). This study highlights some new insights into the peculiar biological and genomic characteristics of phage.

Smart Table Tennis Racket with Tunable Stiffness for Diverse Play Styles and Unconventional Technique Training (Adv. Mater. Technol. 10/2021)

Smart Table Tennis Racket In article number 2100535, Mengying Zhang, Jinbo Wu, and coworkers invent a smart table tennis racket with tunable stiffness based on electrorheological elastomers. The racket face is a multilayer structure of rubber, soft electrode, anisotropic electrorheological elastomer and copper electrode. By applying an electric field, the smart racket successfully changed the trajectory of balls, reduced ejection angle and increased ejection velocity to adapt to diverse play styles and improve unconventional play technique.

Smart Table Tennis Racket with Tunable Stiffness for Diverse Play Styles and Unconventional Technique Training

AbstractSmart technologies bring innovation to the life and sports arena. To adapt to diverse play styles and improve unconventional technique of table tennis players, a smart table tennis racket with tunable stiffness based on anisotropic electrorheological elastomers (EREs) is developed. The EREs are prepared in the designed mold under the electric field to form an anisotropic structure that consisted of electrorheological particles and facilitated the generation of interparticle saturation surface polarization and the local electric field. Therefore, the electrorheological property of anisotropic EREs is significantly promoted, attaining a relative electrorheological effect of 17 160% in shear mode, and the incremental shear storage and compression modulus of 5.2 and 6.4 MPa. By applying an electric field, the smart racket successfully changes the trajectory of balls, reduced ejection angle by 11% and increased ejection velocity by 2%.

Kinematic Analysis of the Racket Position during the Table Tennis Top Spin Forehand Stroke

The present study aims to assess the position of the racket, and racket height with respect to the floor, during the table tennis top spin stroke. A stereophotogrammetric system (Smart-D, BTS, 8 cameras, 550 Hz) was used to track the table tennis racket during cross-court (CC) and long-line (LL) shots. Ten national level players completed ten CC and ten LL top spin strokes responding to a robot machine. The racket motion throughout the shot showed specific technical characteristics: the minimum height of the racket was detected during the backswing phase; racket height at the end of backswing phase (maximal distance racket/table) was higher than the minimum; height at the racket maximum velocity (ball/racket impact) was greater than the net’s height. Furthermore, the maximum height of the racket occurred at the end of the forward swing. No differences in these kinematic variables between CC and LL were found. Conversely, a higher inclination of the racket at the moment of maximum speed was detected in LL vs. CC. From a practical perspective, the present findings suggest that table tennis players need to introduce specific exercises in order to increase the height of the racket during the forehand top spin stroke, to improve its effectiveness.

Epidemiology of racket and paddle sports-related injuries treated in the United States emergency departments, 2007–2016

ABSTRACT Objective Racket and paddle sports are popular worldwide. Although there are several epidemiologic studies on tennis, there are limited epidemiologic studies on injuries in badminton, squash, racquetball, table tennis, pickleball and other racket and paddle sports. We aimed to analyze acute racket and paddle sports injuries that presented to emergency departments. Design Descriptive epidemiologic study; level of evidence 3. Setting United States emergency departments (USEDs) Methods Data from National Electronic Injury Surveillance System (NEISS) were queried to characterize racket and paddle sports-related (RPSR) injuries that presented to USEDs over a 10-year period. Results From 2007 to 2016, there were 7,723 cases of racket and paddle sports-related (RPSR) injuries that presented to USEDs. This data provides a weighted estimate of 301,038 RPSR injuries in USEDs over the 10-year study period. The majority (60.3) of these injuries were in men. Men had a higher percentage of injuries of most body parts except the lower arm, wrist, and ankle. The mean age at the time of injury was 37 years. The highest percentage of sprains, strains, and lower extremity injuries occurred in athletes between ages 18–40 years. Between sports, table tennis had highest percentage of skin and internal organ injuries while badminton had the highest percentage of sprains, strains, fractures, and dislocations. Conclusion This study is the largest nationally representative study of RPSR injuries to date. RPSR injuries are varied in their presentation based on age, sex, body location, and type of injury. Clinical relevance This study determined common RPSR injuries presenting to USEDs, their patterns, and severity over a 10-year period. Researchers and clinicians can begin to use this data for future research studies and may consider this early data in management decisions.

Detection of illegal treatment of table tennis rackets using gas chromatography coupled to ion mobility spectrometry – A feasibility study

In all professional sports, performance pressure is high at the top level. Therefore, rules are defined and controlled to keep sports fair in accordance e.g. with the Agenda 21 of the International Olympic Committee. However, it’s about money and honour and as a consequence it is obvious that the athletes will go to the limits at all levels or even beyond. This is not only true for performance-enhancing substances to improve the physical capacity but – when sports equipment is involved – also for their optimisation. Thus, rules and related controls are necessary with regard to fairness between competitors but also with regard to their health when chemicals are involved. In table tennis, such chemicals (so-called boosters) are used occasionally – but against the rules – to improve the performance of the rackets. In the present study, several boosters were analysed as well as numerous common racket coverings using ion mobility spectrometry coupled to gas-chromatographic pre-separation. After optimisation of sampling with regard to improving reproducibility, characteristic patterns of volatiles for booster compounds and for racket coverings with different characteristics were developed successfully. In particular, signals related to particular softening agents could be identified and detected even in the untreated coverings. The patterns of volatiles were found to be characteristic for the particular boosters investigated as well as for the particular coverings. Furthermore, those patterns enable a differentiation between booster and covering or – in other words – between rule-consistent racket coverings and rule violation by after treatment of the rubber with a booster. After adaptation of the entire procedure to realistic competition situations, the method could be used for proving an infringement against the prohibition of applying such compounds.

Evaluation of restitution performance and examination of estimate equation of coefficient of restitution of table tennis racket

Evaluation of restitution performance and examination of estimate equation of coefficient of restitution of table tennis racket

Inspiration from table tennis racket: Preparation of rubber-wood-bamboo laminated composite (RWBLC) and its response characteristics to cyclic perpendicular compressive load

Inspired by table tennis racket, ten assembly patterns of 7-ply rubber-wood-bamboo laminated composites (RWBLCs) were prepared, and physical, static destructive mechanics and pendulum impact tests were conducted, seeking for the possibility of rubber protecting natural biomass material, for better performance in the area of construction and transportation. The response of RWBLCs to cyclic perpendicular compressive load and its sensitivity to temperature (140, 170, 200, 230, 260 °C) were analyzed. Results indicated that RWBLCs’ density raised as the proportion of rubber increased, however hardly affect the lightweight design of laminated biomass composites. The structure PPPPPPP performed the poorest underwater dimensional stability, while the opposite for RPPRPPR and PRPRPRP. The RWBLCs RPPPPPR, RPPBPPR and RPBBBPR, had superior bending, shearing, and pendulum impact capacity. Synthesis analysis of load–displacement curves, thickness decrement and energy change implied that “table tennis racket” structures (RPPPPPR, RPPRPPR, RPPBPPR, RPBBBPR, RPBB′BPR) achieved great damping aseismic performance and above-average deformation resistance. As temperature increased, the degree of crystallinity of wood and bamboo experienced a slight rise and distinct fall within 140~200 °C and 230~260 °C, respectively. Besides, biomass material suffered evident pyrogenic decomposition of cellulose and lignin at 260 °C that RWBLCs could not withstand whole ten cycles of perpendicular compression, except RPPBPPR.

Haptic Perception of Physical and Functional Properties of Table Tennis and Badminton Rackets in Children and Elderly

Haptic Perception of Physical and Functional Properties of Table Tennis and Badminton Rackets in Children and Elderly

Rich lamellar crystal baklava-structured PZT/PVDF piezoelectric sensor toward individual table tennis training

Real-time monitoring of interaction between ball and racket can provide the extremely important information for high quality guidance of individual table tennis training. However, the existing visual monitoring system is hard to reflect the specific interaction force and accurate hit position. Here, we design a self-powered rich lamellar crystal baklava-structured PZT/PVDF piezoelectric sensor for real-time monitoring of table tennis training and the scalable sports. This unique baklava-structured piezocomposite could be massively manufactured by a facile two step method of nonsolvent induced phase separation and hot-press process. As a result, the as-developed sensor exhibits preeminent sensitivity (6.38 mV/N) and ultrafast response time (21 ms). On this basis, we made a smart table tennis racket embedded with 6 × 6 units, which could real-timely fetch the hit location and contact force, then it could provide evaluation and individual guidance for the athletes training. Admittedly, this work not only opens a new way for real-time monitoring of impact location and force in table tennis training beyond current visual detection system, but also paves a new prospect for artificial intelligence electronics toward smart sports.

Table Tennis Ball Impacting Racket Polymeric Coatings: Experiments and Modeling of Key Performance Metrics

The performance of a table tennis racket is often associated with subjective or quantitative criteria such as the adhesion, the control and the speed. Overall, the so-called performance aims at characterizing the impact with the ball. Ultimately, the polymeric layers glued onto the wooden blade play a key role, as evidenced in a previous work where the normal linear (no spin) impact of a ball onto polymeric layers was experimentally and numerically investigated. In this work, more realistic loading conditions leading to varying the incident angle and spin of the ball, were explored. While the sole linear restitution coefficient was determined in the anterior normal impact study, new physical metrics were identified to describe fully the trajectory of the reflected ball after impact. A companion 3D finite elements model was developed where the polymeric time-dependent dissipative compliant behavior measured with dynamic mechanical analysis and compression tests was accounted for. The confrontations with the experimental data highlighted the key role of the polymer intrinsic properties along with the friction coefficient between the ball and the polymer external layer.

Acoustics of ping-pong: Vibroacoustic analysis of table tennis rackets and balls

ABSTRACTThe sound resulting from the impact of a table tennis racket and ball can influence a player’s perception of equipment quality in addition to providing clues to personal performance. This study explores the vibrational modes of both racket and ball and how those modes contribute to the impact sound. Experimental modal analysis reveals that the racket exhibits a large number of structural vibration modes typical of elliptical plates. Acoustic analysis reveals that two of those structural modes dominate the sound produced by the ball-paddle impact. The rubber padding provides some damping and a significant mass loading to the racket vibrations. The hollow cellulose nitrate balls exhibit vibrational modes typical of a hollow spherical shell, starting with frequencies around 5920 Hz. Experimental frequencies confirm theoretical and computational models. However, the contact time between racket and ball is long enough that the lowest acoustic modes of the ball do not contribute to the radiated sound. Instead, acoustic analysis suggests that the ball appears to radiate sound at a much higher frequency sound (8.5–12 kHz) most likely due to snap-through after buckling common to spherical shells undergoing deformation while impacting a rigid surface at high speeds.

The characteristics of the coefficient of restitutions of table tennis rackets made of wooden laminated plate

The characteristics of the coefficient of restitutions of table tennis rackets made of wooden laminated plate

Effect of Natural Frequency on Coefficient of Restitution of Table Tennis Racket.

Effect of Natural Frequency on Coefficient of Restitution of Table Tennis Racket.

Developing an audio analyzer for instantaneous stroke position identification on table tennis racket to assist technical training

This study has successfully developed an audio analyzer system to identify the stroke position on table tennis racket instantaneously, which can effectively help the technical training. It’s well known, a good stroke is often determined by the exact stroke position on table tennis racket during the play. Therefore, instantaneous identification of the stroke position on table tennis racket during play can provide good adjusting reference of action and effectively help the technical training. In this research, this developed audio analyzer consists of a microphone and the analysing program with fast Fourier transform (FFT) using LabVIEW software. The face of table tennis racket is divided into four blocks which are the center, the left-of-center, the right-of-center, and the trail. The stroke sound generated between table tennis racket and ball during play is captured by the microphone and synchronously analyzed through FFT to determine the principal frequency, where the different stroke position on the table tennis racket yields different principal frequency. The results of calibration show that every table tennis racket has three characteristic principal frequencies on the four blocks, which can distinguish center, right/left, and trail respectively. The positional verification rate of the center position identification is all higher than 90% even up to 100% which can assist technical training.

Integrative square-grid triboelectric nanogenerator as a vibrational energy harvester and impulsive force sensor

A square-grid triboelectric nanogenerator (SG-TENG) is demonstrated for harvesting vibrational energy and sensing impulsive forces. Each square of the three-dimensional (3D)-printed square grid is filled with an aluminum (Al) ball. The grid structure allows the SG-TENG to harvest vibrational energy over a broad bandwidth and operate at different vibrational angles. The most striking feature of the SG-TENG is its ability of being scaled and integrated. After connecting two SG-TENGs in parallel, the open-circuit voltage and short-circuit current are significantly increased over the full vibrational frequency range. Being integrated with a table tennis racket, the SG-TENG can harvest the vibrational energy from hitting a ping pong ball using the racket, where a direct hit by the racket generates an average output voltage of 10.9 ± 0.6 V and an average output current of 0.09 ± 0.02 μA. Moreover, the SG-TENG integrated into a focus mitt can be used in various combat sports, such as boxing and taekwondo, to monitor the frequency and magnitude of the punches or kicks from boxers and other practitioners. The collected data allow athletes to monitor their status and improve their performance skills. This work demonstrates the enormous potential of the SG-TENG in energy harvesting and sensing applications.

Vibroacoustic analysis of table tennis rackets and balls: The acoustics of ping pong

Table Tennis rackets (ping-pong paddles) exhibit a large number of structural vibration modes which follow patterns first observed by Ernst Chladni and Mary Waller for elliptical plates. Vibrational mode shapes and frequencies obtained through experimental modal analysis will be shown. Acoustic analysis reveals that one structural mode of the paddle, in particular, dominates the sound produced by the ball-paddle impact. The rubber padding provides some damping, and a significant mass loading to the paddle vibrations. The hollow cellulose nitrate balls exhibit a number of vibrational mode shapes typical of a hollow spherical shell, starting at frequencies around 5900 Hz; these will be demonstrated from experimental and computational results. However, the contact time between ball and paddle is such that the lowest acoustic modes of the ball do not contribute to the radiated sound. Instead, the ball appears to radiate sound at a much higher frequency sound (10-12 kHz) most likely due to snap-through buckling common to spherical shells undergoing deformation while impacting a rigid surface at high speeds.