19,376 research outputs found
Network Synchronization in a Noisy Environment with Time Delays: Fundamental Limits and Trade-Offs
We study the effects of nonzero time delays in stochastic synchronization
problems with linear couplings in an arbitrary network. Using the known exact
threshold value from the theory of differential equations with delays, we
provide the synchronizability threshold for an arbitrary network. Further, by
constructing the scaling theory of the underlying fluctuations, we establish
the absolute limit of synchronization efficiency in a noisy environment with
uniform time delays, i.e., the minimum attainable value of the width of the
synchronization landscape. Our results have also strong implications for
optimization and trade-offs in network synchronization with delays.Comment: 3 figure
Top-mounted inlet system feasibility for transonic-supersonic fighter aircraft
The more salient findings are presented of recent top inlet performance evaluations aimed at assessing the feasibility of top-mounted inlet systems for transonic-supersonic fighter aircraft applications. Top inlet flow field and engine-inlet performance test data show the influence of key aircraft configuration variables-inlet longitudinal position, wing leading-edge extension planform area, canopy-dorsal integration, and variable incidence canards-on top inlet performance over the Mach range of 0.6 to 2.0. Top inlet performance data are compared with those or more conventional inlet/airframe integrations in an effort to assess the viability of top-mounted inlet systems relative to conventional inlet installations
Phase transition in a log-normal Markov functional model
We derive the exact solution of a one-dimensional Markov functional model
with log-normally distributed interest rates in discrete time. The model is
shown to have two distinct limiting states, corresponding to small and
asymptotically large volatilities, respectively. These volatility regimes are
separated by a phase transition at some critical value of the volatility. We
investigate the conditions under which this phase transition occurs, and show
that it is related to the position of the zeros of an appropriately defined
generating function in the complex plane, in analogy with the Lee-Yang theory
of the phase transitions in condensed matter physics.Comment: 9 pages, 5 figures. v2: Added asymptotic expressions for the
convexity-adjusted Libors in the small and large volatility limits. v3: Added
one reference. Final version to appear in Journal of Mathematical Physic
Dynamical decoherence of the light induced interlayer coupling in YBaCuO
Optical excitation of apical oxygen vibrations in
YBaCuO has been shown to enhance its c-axis
superconducting-phase rigidity, as evidenced by a transient blue shift of the
equilibrium inter-bilayer Josephson plasma resonance. Surprisingly, a transient
c-axis plasma mode could also be induced above T by the same apical
oxygen excitation, suggesting light activated superfluid tunneling throughout
the pseudogap phase of YBaCuO. However, despite the
similarities between the above T transient plasma mode and the
equilibrium Josephson plasmon, alternative explanations involving high mobility
quasiparticle transport should be considered. Here, we report an extensive
study of the relaxation of the light-induced plasmon into the equilibrium
incoherent phase. These new experiments allow for a critical assessment of the
nature of this mode. We determine that the transient plasma relaxes through a
collapse of its coherence length rather than its carrier (or superfluid)
density. These observations are not easily reconciled with quasiparticle
interlayer transport, and rather support transient superfluid tunneling as the
origin of the light-induced interlayer coupling in
YBaCuO.Comment: 27 pages (17 pages main text, 10 pages supplementary), 5 figures
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