48,718 research outputs found
Thermostating by Deterministic Scattering: Heat and Shear Flow
We apply a recently proposed novel thermostating mechanism to an interacting
many-particle system where the bulk particles are moving according to
Hamiltonian dynamics. At the boundaries the system is thermalized by
deterministic and time-reversible scattering. We show how this scattering
mechanism can be related to stochastic boundary conditions. We subsequently
simulate nonequilibrium steady states associated to thermal conduction and
shear flow for a hard disk fluid. The bulk behavior of the model is studied by
comparing the transport coefficients obtained from computer simulations to
theoretical results. Furthermore, thermodynamic entropy production and
exponential phase-space contraction rates in the stationary nonequilibrium
states are calculated showing that in general these quantities do not agree.Comment: 16 pages (revtex) with 9 figures (postscript
A formal theory of cubical complexes Formal report, 1 Sep. 1968 - 30 Apr. 1969
Algorithm for computation of test failures in cyclic circuit
Acoustic characteristics of externally blown flap systems with mixer nozzles
Noise tests were conducted on a large scale, cold flow model of an engine-under-the-wing externally blown flap lift augmentation system employing a mixer nozzle. The mixer nozzle was used to reduce the flap impingement velocity and, consequently, try to attenuate the additional noise caused by the interaction between the jet exhaust and the wing flap. Results from the mixer nozzle tests are summarized and compared with the results for a conical nozzle. The comparison showed that with the mixer nozzle, less noise was generated when the trailing flap was in a typical landing setting (e.g., 60 deg). However, for a takeoff flap setting (20 deg), there was little or no difference in the acoustic characteristics when either the mixer or conical nozzle was used
Dynamics of mesoscopic precipitate lattices in phase separating alloys under external load
We investigate, via three-dimensional atomistic computer simulations, phase
separation in an alloy under external load. A regular two-dimensional array of
cylindrical precipitates, forming a mesoscopic precipitate lattice, evolves in
the case of applied tensile stress by the movement of mesoscopic lattice
defects. A striking similarity to ordinary crystals is found in the movement of
"meso-dislocations", but new mechanisms are also observed. Point defects such
as "meso-vacancies" or "meso-interstitials" are created or annihilated locally
by merging and splitting of precipitates. When the system is subjected to
compressive stress, we observe stacking faults in the mesoscopic
one-dimensional array of plate-like precipitates.Comment: 4 pages, 4 figures, REVTE
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