RESUMO
Although the vibration of rackets and the location of the sweet spot for players when hitting the ball is crucial, manufacturers do not specify this behavior precisely. This article analyses padel rackets, provides a solution to determine the sweet spot position (SSP), quantifies its behavior, and determines the level of vibration transmitted along the racket handle. The proposed methods serve to locate the SSP without quantifying it. This article demonstrates the development of equipment capable of analyzing the vibration behavior of padel rackets. To do so, it employs a robot that moves along the surface of the padel racket, striking it along its central line. Accelerometers are placed on a movable cradle where rackets are positioned and adjusted. A method for analyzing accelerometer signals to quantify vibration severity is proposed. The SSP and vibration behavior along the central line are determined and quantified. As a result of the study, 225 padel rackets are analyzed and compared. SSP is independent of the padel racket shape, balance, weight, moment of inertia, and padel racket shape (tear, diamond, or round) and is not located at the same position as the center of percussion.
RESUMO
Although the moment of inertia of padel rackets is one of their fundamental properties and of particular interest to the players, hardly any manufacturer specifies the parameter for its rackets. The present paper offers a solution to determine the moment of inertia around different axes of padel rackets and makes a standardized comparison possible. After a short overview of the physical background of the problem and the existing solutions for inertia testing, the developed concept for a test stand is described in detail. The approach uses the fact that a pendulum swings with its natural frequency, which depends directly on its moment of inertia. The inertia can be calculated by measuring the cycle time of the swing. Two different test stands, a trifilar and a swing pendulum, are designed to enable an oscillation of the rackets with different rotation axes, and an acceleration sensor is used to measure its natural frequency. A user-friendly interface acquires and processes accelerometer data providing inertial moments. A calibration model defines sensor accuracy. Precision is estimated by calculating the influence of the measurement errors and by testing the repeatability. The maneuverability parameter is created, and in the last step, various rackets are evaluated to create a database with the main properties. As a result of the study of the racket population, a maneuverability parameter is proposed to classify the rackets in a comprehensible way for users. The classification method is tested with users to explore the matching between the scientific classification and the player's feelings. The results are shown and explained.
Assuntos
Modalidades de Fisioterapia , Fenômenos BiomecânicosRESUMO
Assisted reproductive technologies are well-established treatments for many types of subfertility representing substantial economic and healthcare implications for patients, healthcare providers and society as a whole. In order to optimize outcomes according to the type of gonadotrophins within an oocyte donor programme, we performed an economic evaluation based on data collected in a multicentre, prospective, randomized study within three private clinics belonging to the IVI Group. Results showed no relevant between-group differences in the clinical variables. According to the economic analysis, ovarian stimulation with corifollitropin alfa increased the overall cost of the treatment as well as the cost per retrieved and effective oocyte, although the differences were not statistically significant. In conclusion, cost savings can be achieved using cheaper gonadotrophins during ovarian stimulation. The cost of corifollitropin alfa compared with recombinant FSH and highly purified human menopausal gonadotrophin should be considered when making treatment decisions.