3,678 research outputs found
Exact Moving and Stationary Solutions of a Generalized Discrete Nonlinear Schrodinger Equation
We obtain exact moving and stationary, spatially periodic and localized
solutions of a generalized discrete nonlinear Schr\"odinger equation. More
specifically, we find two different moving periodic wave solutions and a
localized moving pulse solution. We also address the problem of finding exact
stationary solutions and, for a particular case of the model when stationary
solutions can be expressed through the Jacobi elliptic functions, we present a
two-point map from which all possible stationary solutions can be found.
Numerically we demonstrate the generic stability of the stationary pulse
solutions and also the robustness of moving pulses in long-term dynamics.Comment: 22 pages, 7 figures, to appear in J. Phys.
Measurements of the Influence of Acceleration and Temperature of Bodies on their Weight
A brief review of experimental research of the influence of acceleration and
temperatures of test mass upon gravitation force, executed between the 1990s
and the beginning of 2000 is provided.Results of weighing a rotor of a
mechanical gyroscope with a horizontal axis, an anisotropic crystal with the
big difference of the speed of longitudinal acoustic waves, measurements of
temperature dependence of weight of metal bars of non-magnetic materials, and
also measurement of restitution coefficients at quasi-elastic impact of a steel
ball about a massive plate are given. A negative temperature dependence of the
weight of a brass core was measured. All observably experimental effects, have
probably a general physical reason connected with the weight change dependent
upon acceleration of a body or at thermal movement of its microparticles.Comment: 7 pages, 6 figures. Presented at the 5-th Symposium on New Frontiers
and Future Concepts (STAIF-2008
Multi-field approach in mechanics of structural solids
We overview the basic concepts, models, and methods related to the
multi-field continuum theory of solids with complex structures. The multi-field
theory is formulated for structural solids by introducing a macrocell
consisting of several primitive cells and, accordingly, by increasing the
number of vector fields describing the response of the body to external
factors. Using this approach, we obtain several continuum models and explore
their essential properties by comparison with the original structural models.
Static and dynamical problems as well as the stability problems for structural
solids are considered. We demonstrate that the multi-field approach gives a way
to obtain families of models that generalize classical ones and are valid not
only for long-, but also for short-wavelength deformations of the structural
solid. Some examples of application of the multi-field theory and directions
for its further development are also discussed.Comment: 25 pages, 18 figure
Angular distributions in decays
The differential decay rates of the processes and
close to the threshold are calculated with
the help of the optical potential. The same calculations are made
for the decays of . We use the potential which has been suggested to
fit the cross sections of scattering together with and
six pion production in annihilation close to the
threshold. The invariant mass spectra is in agreement with the
available experimental data. The anisotropy of the angular distributions, which
appears due to the tensor forces in the interaction, is predicted
close to the threshold. This anisotropy is large enough to be
investigated experimentally. Such measurements would allow one to check the
accuracy of the model of interaction.Comment: 10 pages, 8 figure
The anisotropic Heisenberg chain in coexisting transverse and longitudinal magnetic fields
The one-dimensional spin-1/2 model in a mixed transverse and
longitudinal magnetic field is studied. Using the specially developed version
of the mean-field approximation the order-disorder transition induced by the
magnetic field is investigated. The ground state phase diagram is obtained. The
behavior of the model in low transverse field is studied on the base of
conformal field theory. The relevance of our results to the observed phase
transition in the quasi-one-dimensional antiferromagnet is
discussed.Comment: 18 pages, 6 figure
- β¦