19,052 research outputs found
The flow over delta wings at low speeds with leading edge separation
A low speed investigation of the flow over a 40 degree apex angle delta wing with sharp leading edges had been made in order to ascertain details of the flow in the viscous region near the leading edge of the suction surface of the wing. A physical picture of the flow was obtained from the surface flow and a smoke technique of flow visualization, combined with detailed measurements of total head, dynamic pressure, flow directions and vortex core positions in the flow above the wing
Absorption spectrum of iron in the vacuum ultraviolet 2950 - 1588 angstrom
Absorption spectrum of iron in vacuum ultraviole
Stochastic Perturbations of Periodic Orbits with Sliding
Vector fields that are discontinuous on codimension-one surfaces are known as
Filippov systems and can have attracting periodic orbits involving segments
that are contained on a discontinuity surface of the vector field. In this
paper we consider the addition of small noise to a general Filippov system and
study the resulting stochastic dynamics near such a periodic orbit. Since a
straight-forward asymptotic expansion in terms of the noise amplitude is not
possible due to the presence of discontinuity surfaces, in order to
quantitatively determine the basic statistical properties of the dynamics, we
treat different parts of the periodic orbit separately. Dynamics distant from
discontinuity surfaces is analyzed by the use of a series expansion of the
transitional probability density function. Stochastically perturbed sliding
motion is analyzed through stochastic averaging methods. The influence of noise
on points at which the periodic orbit escapes a discontinuity surface is
determined by zooming into the transition point. We combine the results to
quantitatively determine the effect of noise on the oscillation time for a
three-dimensional canonical model of relay control. For some parameter values
of this model, small noise induces a significantly large reduction in the
average oscillation time. By interpreting our results geometrically, we are
able to identify four features of the relay control system that contribute to
this phenomenon.Comment: 44 pages, 9 figures, submitted to: J Nonlin. Sc
Evaluation of ERTS-1 data for acquiring land use data of northern Megalopolis
State planners are increasingly becoming interested in ERTS as a possible method for acquiring land use data. An important consideration to them is whether ERTS can provide such data at a savings in both time and money over alternative systems. A preliminary evaluation of ERTS as a planning tool is given
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