27,673 research outputs found
On the origin of space
Within the framework of fractional calculus with variable order the evolution
of space in the adiabatic limit is investigated. Based on the Caputo definition
of a fractional derivative using the fractional quantum harmonic oscillator a
model is presented, which describes space generation as a dynamic process,
where the dimension of space evolves smoothly with time in the range 0 <=
d(t) <=3, where the lower and upper boundaries of dimension are derived from
first principles. It is demonstrated, that a minimum threshold for the space
dimension is necessary to establish an interaction with external probe
particles. A possible application in cosmology is suggested.Comment: 14 pages 3 figures, some clarifications adde
Folded potentials in cluster physics - a comparison of Yukawa and Coulomb potentials with Riesz fractional integrals
In cluster physics a single particle potential to determine the microscopic
part of the total energy of a collective configuration is necessary to
calculate the shell- and pairing effects. In this paper we investigate the
properties of the Riesz fractional integrals and compare their properties with
the standard Coulomb and Yukawa potentials commonly used. It is demonstrated,
that Riesz potentials may serve as a promising extension of standard potentials
and may be reckoned as a smooth transition from Coulomb to Yukawa like
potentials, depending of the fractional parameter . For the macroscopic
part of the total energy the Riesz potentials treat the Coulomb-, symmetry- and
pairing-contributions from a generalized point of view, since they turn out to
be similar realizations of the same fractional integral at distinct
values.Comment: final versio
Bursts in discontinuous Aeolian saltation
Close to the onset of Aeolian particle transport through saltation we find in
wind tunnel experiments a regime of discontinuous flux characterized by bursts
of activity. Scaling laws are observed in the time delay between each burst and
in the measurements of the wind fluctuations at the fluid threshold Shields
number . The time delay between each burst decreases on average with
the increase of the Shields number until sand flux becomes continuous. A
numerical model for saltation including the wind-entrainment from the turbulent
fluctuations can reproduce these observations and gives insight about their
origin. We present here also for the first time measurements showing that with
feeding it becomes possible to sustain discontinuous flux even below the fluid
threshold
- …
