121,151 research outputs found
Time dependent intrinsic correlation analysis of temperature and dissolved oxygen time series using empirical mode decomposition
In the marine environment, many fields have fluctuations over a large range
of different spatial and temporal scales. These quantities can be nonlinear
\red{and} non-stationary, and often interact with each other. A good method to
study the multiple scale dynamics of such time series, and their correlations,
is needed. In this paper an application of an empirical mode decomposition
based time dependent intrinsic correlation, \red{of} two coastal oceanic time
series, temperature and dissolved oxygen (saturation percentage) is presented.
The two time series are recorded every 20 minutes \red{for} 7 years, from 2004
to 2011. The application of the Empirical Mode Decomposition on such time
series is illustrated, and the power spectra of the time series are estimated
using the Hilbert transform (Hilbert spectral analysis). Power-law regimes are
found with slopes of 1.33 for dissolved oxygen and 1.68 for temperature at high
frequencies (between 1.2 and 12 hours) \red{with} both close to 1.9 for lower
frequencies (time scales from 2 to 100 days). Moreover, the time evolution and
scale dependence of cross correlations between both series are considered. The
trends are perfectly anti-correlated. The modes of mean year 3 and 1 year have
also negative correlation, whereas higher frequency modes have a much smaller
correlation. The estimation of time-dependent intrinsic correlations helps to
show patterns of correlations at different scales, for different modes.Comment: 35 pages with 22 figure
Optimized Double-well quantum interferometry with Gaussian squeezed-states
A Mach-Zender interferometer with a gaussian number-difference squeezed input
state can exhibit sub-shot-noise phase resolution over a large phase-interval.
We obtain the optimal level of squeezing for a given phase-interval
and particle number , with the resulting phase-estimation
uncertainty smoothly approaching as approaches 10/N,
achieved with highly squeezed states near the Fock regime. We then analyze an
adaptive measurement scheme which allows any phase on to be
measured with a precision of requiring only a few measurements, even
for very large . We obtain an asymptotic scaling law of , resulting in a final
precision of . This scheme can be readily implemented in a
double-well Bose-Einstein condensate system, as the optimal input states can be
obtained by adiabatic manipulation of the double-well ground state.Comment: updated versio
Lagrangian Cascade in Three-Dimensional Homogeneous and Isotropic Turbulence
In this work, the scaling statistics of the dissipation along Lagrangian
trajectories are investigated by using fluid tracer particles obtained from a
high resolution direct numerical simulation with . Both the
energy dissipation rate and the local time averaged
agree rather well with the lognormal distribution hypothesis.
Several statistics are then examined. It is found that the autocorrelation
function of and variance of
obey a log-law with scaling exponent
compatible with the intermittency parameter . The
th-order moment of has a clear power-law on the inertial
range . The measured scaling exponent agrees
remarkably with where is the scaling exponent
estimated using the Hilbert methodology. All these results suggest that the
dissipation along Lagrangian trajectories could be modelled by a multiplicative
cascade.Comment: 10 pages with 7 figures accepted for Journal of Fluid Mechanics as
Rapid
Free-standing all-polymer microring resonator optical filter
Free-standing all-polymer microring resonator optical filters as prototypical elements in flexible integrated lightwave circuits are demonstrated. The fabrication and measurement methods are discussed. The measured spectrum shows good agreement with theoretical expectations. The crucial 'critical' coupling condition is achieved, resulting in a measurement limited -27 dB extinction of the filter output on resonances
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