Classification of Plank Techniques Using Wearable Sensors

Abstract

The plank is a common core-stability exercise. Developing a wearable inertial sensor system for distinguishing between acceptable and aberrant plank techniques and detecting specific deviations from acceptable plank techniques can enhance performance and prevent injury. The purpose of this study was to develop an inertial measurement unit (IMU)-based plank technique quantification system. Nineteen healthy volunteers (age: 20.5 ± 0.8 years, BMI: 22.9 ± 1.4 kg/m2) performed the standard plank technique and six deviations with five IMUs positioned on the occiput, cervical spine, thoracic spine, sacrum, and right radius to record movements. The random forest method was employed to perform the classification. The proposed binary tree classification model achieved an accuracy of more than 86%. The average sensitivities were higher than 90%, and the specificities were higher than 91%, except for one deviation (83%). These results suggest that the five IMU-based systems can classify the plank technique as acceptable or aberrant with good accuracy, high sensitivity, and acceptable specificity, which has significant implications in monitoring plank biomechanics and enabling coaching practice.

Cryogenic Systems for Astronomical Research in the Special Astrophysical Observatory of the Russian Academy of Sciences

“…The minimum achievable operating temperature in such a cryostat can reach 50 mK (without a background load in the absence of an optical window) and nanowatt capacity. In addition to the achievability of such low temperatures, another advantage of this device is the absence of pulse tubes (which contribute to the total noise of the receiving system) because pumping of 3 He and 4 He is carried out using built-in sorption pumps. But there is also a certain drawback of such a cryogenic system, specifically that the duty cycle is no more than 8 h. This generally fits into the ideology of using time unoccupied by night optical observations for sub-THz observations on an optical telescope.…”

“…To ensure long-term temperature maintenance of the operating temperature of the detector, a modification of the cryogenic system presented in the previous section was carried out [54]. The principle of operation is based on the technology of sorption pumping 3 He and 4 He and condensation pumping of the mixture 3 He-4 He in the dissolution cycle. The continuous maintenance of a low temperature of the order of 0.1 K during the regeneration of sorbents is carried out due to the large heat capacity of the block filled with holmium plates, in which the condensation of circulating helium occurs.…”

“…ty. In addition to the achievability of such low temperatures, another advantage o device is the absence of pulse tubes (which contribute to the total noise of the rec system) because pumping of 3 He and 4 He is carried out using built-in sorption p But there is also a certain drawback of such a cryogenic system, specifically that the cycle is no more than 8 h. This generally fits into the ideology of using time unocc by night optical observations for sub-THz observations on an optical telescope. At when observations are made in optics, 3 He will be recondensed.…”

“…Initially, astronomy developed in the optical range, and since the second quarter of the 20th century, in the radio range as well. The last century of the development of astronomy was characterized by the expansion of the spectrum and the filling of the space between the optical and radio ranges [1,2], as well as an advance towards shorter wavelengths than optics [3][4][5]. The critical limitation in this range was not only the technology of the Photonics 2023, 10, 1263 2 of 22 equipment with its fundamental quantum limitations, but also the atmosphere, which affects the propagation of electromagnetic waves [6].…”

“…The 4 He unit that includes a 1 K chamber and a 3 He condensation volume, which constitute a common unit, and a sorption pump that evacuates helium vapors. The 4 He sorber (as well the 3 He sorber) is above the 4 He bath and both 3 He baths. Heat is withdrawn from the sorber to liquid helium in the portable Dewar flask through copper heat conductors.…”