Contrasting Age Effects on Complexity of Tracking Force and Force Fluctuations During Monorhythmic Contraction

This study contrasted the stochastic force component between young and older adults, who performed pursuit tracking/compensatory tracking by exerting in-phase/antiphase forces to match a sinusoidal target. Tracking force was decomposed into the force component containing the target frequency and the nontarget force fluctuations (stochastic component). Older adults with inferior task performance had higher complexity (entropy across time; p = .005) in total force. For older adults, task errors were negatively correlated with force fluctuation complexity (pursuit tracking: r = −.527 to −.551; compensatory tracking: r = −.626 to −.750). Notwithstanding an age-related increase in total force complexity (p = .004), older adults exhibited lower complexity of the stochastic force component than young adults did (low frequency: p = .017; high frequency: p = .035). Those older adults with a higher complexity of stochastic force had better task performance due to the underlying use of a richer gradation strategy to compensate for impaired oscillatory control.

THEORETICAL STUDY OF THE STABILITY OF THE ELASTIC TUBING BOX

The use of subsoil-scattered seeding of cereal crops allows to achieve seed distribution on the packed bed along the entire width of the seeding machine. With this seeding method, the seeds are evenly distributed relative to each other, which creates the same conditions for nutrition and plant growth. In order to obtain a better distribution of seeds in the podlag space, the use of air flow is suggested when transporting seeds from the seeder to the opener and the oscillatory process of the distributor. The flow of the air-grain flow from the cantilevered suspension elastic tube causes the action of longitudinal compressive forces, the directions of which coincide with the tangent to the axis at the end of the tube, that is, the so-called “tracking” force arises. The deviations of an elastic scattering pipe under conditions of relatively small and large deviations from the axis of the pipe are considered. This approach of theoretical research allows us to judge the correctness of the selected models by agreeing on the results obtained. Based on the results of the study, analytical expressions were obtained that allow us to determine the coordinates of the location of the deflected tube as a function of the speed of the air-grain flow for a qualitative distribution of seeds in the sublobe space, the critical value of the tube deflection angle equal to θ = 1.173 rad, which corresponds to the coefficient of friction of the medium fm = 0 , 2.

Cases of integrability corresponding to the pendulummotion on the plane

In this article, we systemize the results on the study of plane-parallel motion equations of fixed rigid body-pendulum which is placed in certain nonconserva- tive force field. In parallel, we consider the problem of a plane-parallel motion of a free rigid body which is also placed in a similar force field. Thus, the non-conservative tracking force operates onto this body. That force forces the value of certain point of a body to be constant for all the time of a motion, which means the existence of nonintegrable servoconstraint in the system. The obtained results are systematized and served in the invariant form. We also show the nontrivial topological and mechanical analogies.