6,806 research outputs found
Slowly modulated oscillations in nonlinear diffusion processes
It is shown here that certain systems of nonlinear (parabolic) reaction-diffusion equations have solutions which are approximated by oscillatory functions in the form R(ξ - cτ)P(t^*) where P(t^*) represents a sinusoidal oscillation on a fast time scale t* and R(ξ - cτ) represents a slowly-varying modulating amplitude on slow space (ξ) and slow time (τ) scales. Such solutions describe phenomena in chemical reactors, chemical and biological reactions, and in other media where a stable oscillation at each point (or site) undergoes a slow amplitude change due to diffusion
Bernard v. Gulf Oil Co., 619 F.2d 459 (5th Cir. 1980)
Constitutional Law-FIRST AMENDMENT-PRIOR RESTRAINT-CLASS ACTIONS-SILENCE IS GOLDEN, BUT A RULE 23(d) JUDICIAL ORDER IS AN UNCONSTITUTIONAL PRIOR RESTRAINT ON SPEEC
A simple and optimal ancestry labeling scheme for trees
We present a ancestry labeling scheme for trees. The
problem was first presented by Kannan et al. [STOC 88'] along with a simple solution. Motivated by applications to XML files, the label size was
improved incrementally over the course of more than 20 years by a series of
papers. The last, due to Fraigniaud and Korman [STOC 10'], presented an
asymptotically optimal labeling scheme using
non-trivial tree-decomposition techniques. By providing a framework
generalizing interval based labeling schemes, we obtain a simple, yet
asymptotically optimal solution to the problem. Furthermore, our labeling
scheme is attained by a small modification of the original solution.Comment: 12 pages, 1 figure. To appear at ICALP'1
Temperature can enhance coherent oscillations at a Landau-Zener transition
We consider sweeping a system through a Landau-Zener avoided-crossing, when
that system is also coupled to an environment or noise. Unsurprisingly, we find
that decoherence suppresses the coherent oscillations of quantum superpositions
of system states, as superpositions decohere into mixed states. However, we
also find an effect we call "Lamb-assisted coherent oscillations", in which a
Lamb shift exponentially enhances the coherent oscillation amplitude. This
dominates for high-frequency environments such as super-Ohmic environments,
where the coherent oscillations can grow exponentially as either the
environment coupling or temperature are increased. The effect could be used as
an experimental probe for high-frequency environments in such systems as
molecular magnets, solid-state qubits, spin-polarized gases (neutrons or He3)
or Bose-condensates.Comment: 4 Pages & 4 Figs - New version: introduction extended & citations
adde
Numerical Analysis of Solid Rocket Motor Instabilities With AP Composite Propellants
A non-steady model for the combustion of ammonium
perchlorate composite propellants has been developed
in order to be incorporated into a comprehensive gasdynamics
model of solid rocket motor flow fields. The
model including the heterogeneous combustion and turbulence
mechanisms is applied to nonlinear combustion
instability analyses. This paper describes the essential
mechanisms and features of the model and discusses the
methodology of non-steady calculations of the combustion
instabilities of solid rocket motors
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