1,394 research outputs found
Non-relativistic limit of multidimensional gravity: exact solutions and applications
It is found the exact solution of the Poisson equation for the
multidimensional space with topology . This
solution describes smooth transition from the newtonian behavior for
distances bigger than periods of tori (the extra dimension sizes) to
multidimensional behavior in opposite limit. In the case of
one extra dimension , the gravitational potential is expressed via compact
and elegant formula. These exact solutions are applied to some practical
problems to get the gravitational potentials for considered configurations.
Found potentials are used to calculate the acceleration for point masses and
gravitational self-energy.It is proposed models where the test masses are
smeared over some (or all) extra dimensions. In 10-dimensional spacetime with 3
smeared extra dimensions, it is shown that the size of 3 rest extra dimensions
can be enlarged up to submillimeter for the case of 1TeV fundamental Planck
scale . In the models where all extra dimensions are smeared, the
gravitational potential exactly coincides with the newtonian one regardless of
size of the extra dimensions. Nevertheless, the hierarchy problem can be solved
in these models.Comment: LaTex file, 18 pages, 4 figure
On cogrowth function of algebras and its logarithmical gap
Let be an associative algebra. A finite word
over alphabet is {\it-reducible} if its image in is a -linear
combination of length-lexicographically lesser words. An {\it obstruction} in a
subword-minimal -reducible word. A {\em cogrowth} function is number of
obstructions of length . We show that the cogrowth function of a
finitely presented algebra is either bounded or at least logarithmical. We also
show that an uniformly recurrent word has at least logarithmical cogrowth.Comment: 5 page
Detection and masking of Trojan Circuits in sequential logic
A technique of finding a set of sequential circui
External high-frequency control of combustion instability
The article presents the results of experimental studies of combustion instability in the pulse combustor. Propane-air mixture is burned in the chamber with the flame holder. It was experimentally found that feeding high-frequency sound vibrations into the combustion chamber causes the suppression of pulsating combustion. The oscillation frequency ranges in 870 to 1400 Hz. This corresponds to 9-12 resonance frequencies of oscillations in the combustor. The physical mechanism of the observed phenomenon consists in changing the conditions of formation and destruction of fuel jets in the vortex zone behind the flame holder
Preventing and masking Trojan Circuits triggering out of working area
Inserting malicious sub-circuits that may cause
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