Can IMU Provide an Accurate Vertical Jump Height Estimate?

The aim of the present study was to determine if an inertial measurement unit placed on the metatarsal part of the foot can provide valid and reliable data for an accurate estimate of vertical jump height. Thirteen female volleyball players participated in the study. All players were members of the Republic of Serbia national team. Measurement of the vertical jump height was performed for the two exemplary jumping tasks, squat jump and counter-movement jump. Vertical jump height estimation was performed using the flight time method for both devices. The presented results support a high level of concurrent validity of an inertial measurement unit in relation to a force plate for estimating vertical jump height (CMJ t = 0.897, p = 379; ICC = 0.975; SQJ t = −0.564, p = 0.578; ICC = 0.921) as well as a high level of reliability (ICC > 0.872) for inertial measurement unit results. The proposed inertial measurement unit positioning may provide an accurate vertical jump height estimate for in-field measurement of jump height as an alternative to other devices. The principal advantages include the small size of the sensor unit and possible simultaneous monitoring of multiple athletes.

Calculation of Blade Track Height Using an Optical Tracker

Rotor Track and Balance (RTB) is a necessary maintenance action to improve aircraft ride quality and decrease fatigue for both the aircrew and helicopter equipment. While there have been a number of papers discussing the solution strategy for optimizing both blade track split and vibration, little work has been reported on how to calculate blade track by using an optical sensor. This paper will discuss the formulation of the blade track height estimate based on optical tracker measurements from flight-testing. Furthermore, the article will include a sensitivity analysis to define the blade track height error. Finally, contending solutions strategies are tested by comparing the results between two pulse and three pulse optical trackers.

A Sharp Height Estimate for Compact Hypersurfaces with Constant k-Mean Curvature in Warped Product Spaces

In this paper we obtain a sharp height estimate concerning compact hypersurfaces immersed into warped product spaces with some constant higher-order mean curvature and whose boundary is contained in a slice. We apply these results to draw topological conclusions at the end of the paper.

Ash plume top height estimate using AATSR

An algorithm is presented for estimation of volcanic ash plume top height using the stereo view of the Advanced Along Track Scanning Radiometer (AATSR) aboard ENVISAT. The algorithm is based on matching the top of atmosphere (TOA) reflectances and brightness temperatures of the nadir and 55° forward views, and using the resulting parallax to obtain the height estimate. Various retrieval parameters are discussed in detail, several quality parameters are introduced, and post-processing methods for screening out unreliable data have been developed. The method is compared against other satellite observations and in-situ data. The proposed algorithm is designed to be fully automatic, and can be implemented into operational retrieval algorithms. Combined with automated ash detection using the brightness temperature difference between the 11 μm and 12 μm channels, the algorithm allows simultaneous retrieval of horizontal and vertical dispersion of volcanic ash efficiently. A case study on the eruption of the Icelandic volcano Eyjafjallajökull in 2010 is presented. The height estimate method results are validated against available satellite and ground based data.