889 research outputs found
Spatiotemporal communication with synchronized optical chaos
We propose a model system that allows communication of spatiotemporal
information using an optical chaotic carrier waveform. The system is based on
broad-area nonlinear optical ring cavities, which exhibit spatiotemporal chaos
in a wide parameter range. Message recovery is possible through chaotic
synchronization between transmitter and receiver. Numerical simulations
demonstrate the feasibility of the proposed scheme, and the benefit of the
parallelism of information transfer with optical wavefronts.Comment: 4 pages, 5 figure
Chaos and Synchronized Chaos in an Earthquake Model
We show that chaos is present in the symmetric two-block Burridge-Knopoff
model for earthquakes. This is in contrast with previous numerical studies, but
in agreement with experimental results. In this system, we have found a rich
dynamical behavior with an unusual route to chaos. In the three-block system,
we see the appearance of synchronized chaos, showing that this concept can have
potential applications in the field of seismology.Comment: To appear in Physical Review Letters (13 pages, 6 figures
Analytical results for coupled map lattices with long-range interactions
We obtain exact analytical results for lattices of maps with couplings that
decay with distance as . We analyze the effect of the coupling
range on the system dynamics through the Lyapunov spectrum. For lattices whose
elements are piecewise linear maps, we get an algebraic expression for the
Lyapunov spectrum. When the local dynamics is given by a nonlinear map, the
Lyapunov spectrum for a completely synchronized state is analytically obtained.
The critical lines characterizing the synchronization transition are determined
from the expression for the largest transversal Lyapunov exponent. In
particular, it is shown that in the thermodynamical limit, such transition is
only possible for sufficiently long-range interactions, namely, for , where is the lattice dimension.Comment: 4 pages, 2 figures, corrections included. Phys. Rev. E 68, 045202(R)
(2003); correction in pres
ENIGMA-A centralised supervisory controller for enhanced onboard electrical energy management with model in the loop demonstration
A centralised smart supervisor (CSS) controller with enhanced electrical energy management (E2-EM) capability has been developed for an Iron Bird Electrical Power Generation and Distribution System (EPGDS) within the Clean Sky 2 ENhanced electrical energy MAnagement (ENIGMA) project. The E2-EM strategy considers the potential for eliminating the 5 min overload capability of the generators to achieve a substantial reduction in the mass of the EPGDS. It ensures optimal power and energy sharing within the EPGDS by interfacing the CSS with the smart grid network (SGN), the energy storage and regeneration system (ESRS), and the programmable load bank 1 secondary distribution board (PLB1 SDU) during power overloads and failure conditions. The CSS has been developed by formalizing E2-EM logic as an algorithm operating in real time and by following safety and reliability rules. The CSS undergoes initial verification using model-in-the-loop (MIL) testing. This paper describes the EPGDS simulated for the MIL testing and details the E2-EM strategy, the algorithms, and logic developed for the ENIGMA CSS design. The CSS was subjected to two test cases using MIL demonstration, and based on the test results, the performance of the ENIGMA CSS is verified and validated
Retrieval validation during the European Aqua Thermodynamic Experiment
Atmospheric and surface thermodynamic parameters retrieved with advanced hyperspectral remote sensors
aboard Earth observing satellites are critical to weather prediction and scientific research. The retrieval algorithms and
retrieved parameters from satellite sounders must be validated to demonstrate the capability and accuracy of both observation
and data processing systems. The European Aqua Thermodynamic Experiment (EAQUATE) was conducted not only for
validation of the Atmospheric InfraRed Sounder on the Aqua satellite, but also for assessment of validation systems of both
ground-based and aircraft-based instruments that will be used for other satellite systems, such as the Infrared Atmospheric
Sounding Interferometer on the European MetOp satellite, the Cross-track Infrared Sounder from the National Polar-orbiting
Operational Environmental Satellite System (NPOESS) Preparatory Project and the continuing series of NPOESS satellites.
Detailed intercomparisons were conducted and presented using different retrieval methodologies: measurements from
airborne ultraspectral Fourier transform spectrometers, aircraft in situ instruments, dedicated dropsondes and radiosondes,
ground-based Raman lidar, as well as the European Centre for Medium-range Weather Forecasting modelled thermal
structures. The results of this study not only illustrate the quality of the measurements and retrieval products, but also
demonstrate the capability of the validation systems put in place to validate current and future hyperspectral sounding
instruments and their scientific products
Duration of the Process of Complete Synchronizationof Two Coupled Identical Chaotic Systems
We consider the time required for complete synchronization of two identical
one-way coupled vander Pol-Duffing oscillators occurring in the regime of
dynamic chaos. The influence of the initial phase differ-ence between
oscillators on the duration of the process of complete synchronization has been
studied. At a fixedphase of chaotic oscillations of the self-excited drive
oscillator, the period of time (past the coupling onset) during which the
complete synchronization regime is established depends on the phase of the
self-excited responseoscillatorComment: 4 pages, 2 figure
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