43,724 research outputs found
Combustor liner construction
A combustor liner is fabricated from a plurality of individual segments each containing counter/parallel Finwall material and are arranged circumferentially and axially to define the combustion zone. Each segment is supported by a hook and ring construction to an opened lattice frame with sufficient tolerance between the hook and ring to permit thermal expansion with a minimum of induced stresses
Liquid rocket metal tanks and tank components
Significant guidelines are presented for the successful design of aerospace tanks and tank components, such as expulsion devices, standpipes, and baffles. The state of the art is reviewed, and the design criteria are presented along with recommended practices. Design monographs are listed
Simulation of axial channeling radiation on a thin Ge single crystal
Based on classical electrodynamics the radiation emitted by axially
channeled electrons has been investigated by means of computer simulations. Using
the Doyle-Turner approximation for the atomic scattering factor and taking thermal vibrations of atoms into account, we calculated the two-dimensional continuum
potential of the 110 crystallographic axis of a thin Ge single crystal. The trajectories, velocities and accelerations of electrons are obtained by solving the equations
of motion in three dimensions, and the spectral-angular distribution of radiation has
been calculated within classical approach
Enhancement of the stability of genetic switches by overlapping upstream regulatory domains
We study genetic switches formed from pairs of mutually repressing operons.
The switch stability is characterised by a well defined lifetime which grows
sub-exponentially with the number of copies of the most-expressed transcription
factor, in the regime accessible by our numerical simulations. The stability
can be markedly enhanced by a suitable choice of overlap between the upstream
regulatory domains. Our results suggest that robustness against biochemical
noise can provide a selection pressure that drives operons, that regulate each
other, together in the course of evolution.Comment: 4 pages, 5 figures, RevTeX
The Exchange Gate in Solid State Spin Quantum Computation: The Applicability of the Heisenberg Model
Solid state quantum computing proposals rely on adiabatic operations of the
exchange gate among localized spins in nanostructures. We study corrections to
the Heisenberg interaction between lateral semiconductor quantum dots in an
external magnetic field. Using exact diagonalization we obtain the regime of
validity of the adiabatic approximation. We also find qualitative corrections
to the Heisenberg model at high magnetic fields and in looped arrays of spins.
Looped geometries of localized spins generate flux dependent, multi-spin terms
which go beyond the basic Heisenberg model.Comment: 13 pages, 8 figure
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