pressure refers to the feelings an athlete has about performing in a competitive situation. the primary aim of this study was to examine kinematic changes of tennis serves in increasing competitive pressure. 20 semi-professional right-handed male tennis players completed 120 serves under low (normal) and high competitive pressure phases. pressure checks (heart rate and perceived competitive sta...

Magnetic helicity fluxes are investigated in a family of gauges in which the contribution from ideal magnetohydrodynamics takes the form of a purely advective flux. Numerical simulations of magnetohydrodynamic turbulence in this advective gauge family exhibit instabilities triggered by the build-up of unphysical irrotational contributions to the magnetic vector potential. As a remedy, the vecto...

This paper presents a coordinate-invariant differential geometric analysis of manipulability for closed kinematic chains containing active and passive joints. The formulation treats both redundant and nonredundant mechanisms, as well as over-actuated and exactly actuated ones, in a uniform manner. Dynamic characteristics of the mechanism and manipulated object can also be naturally included by ...

This paper investigates range-only tracking with range-Doppler coupling, where the range measurement of a target of interest is linearly biased by its range-rate (or Doppler). In previous treatments the situation was monostatic, and a simple Riccati analysis sufficed, but here the system is multistatic (notionally, a MIMO radar). Here, the closed form of posterior Cramér-Rao bound (PCRB) is der...

In a recent paper we showed that there exist linear controllers which globally asymptotically stabilize the attitude motion of a rigid body using a nonredundant three dimensional set of kinematic parameters In this paper we show using the inherent passivity properties of the system that these results can be extended to stabilizing control laws without any angular velocity measurements A numeric...