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Results for “nonlinear dynamics”
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Resolving Nonlinear Recombination Dynamics in Semiconductors via Ultrafast Excitation Correlation Spectroscopy: Photoluminescence versus Photocurrent Detection
Not Available
Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa2Cu3O6.5
Abstract is not Provided
On the abrupt growth dynamics of nonlinear resistive tearing mode and the viscosity effects
The nonlinear evolution of the resistive tearing mode exhibits an abrupt growth after an X-point collapse once the magnetic island exceeds a certain critical width Δ′w{sub c} for large instability parameter Δ′, leading to a current sheet formation [N. F. Loureiro et al., Phys. Rev. Lett. 95, 235003 (2005)]. In this work, we investigate the underlying mechanism of the X-point collapse as well as the current sheet formation including the viscosity effects, based on a secondary instability analysis. The secondary instability is excited due to the quasilinear current modification by the zonal current. In particular, it is identified that the current peaking effect is plausibly responsible for the onset of the X-point collapse and the current sheet formation, leading to the explosive growth of reconnected flux. In the presence of finite viscosity, the Δ′w{sub c} scaling with the resistivity gets modified. A transition behavior is revealed at P{sub r}≈1 for the viscosity dependence of Δ′w{sub c} and the linear tearing instability. However, the explosive growth seems to be independent of the viscosity in the magnetic Prandtl number P{sub r}<1 regime, while large viscosity plays a strong dissipation role.
Visco-elastic fluid simulations of coherent structures in strongly coupled dusty plasma medium
A generalized hydrodynamic model depicting the behaviour of visco-elastic fluids has often been invoked to explore the behaviour of a strongly coupled dusty plasma medium below their crystallization limit. The model has been successful in describing the collective normal modes of the strongly coupled dusty plasma medium observed experimentally. The paper focuses on the study of nonlinear dynamical characteristic features of this model. Specifically, the evolution of coherent vorticity patches is being investigated here within the framework of this model. A comparison with Newtonian fluids and molecular dynamics simulations treating the dust species interacting through the Yukawa potential has also been presented.
Experimental parameters, combined dynamics, and nonlinearity of a magnonic-opto-electronic oscillator (MOEO)
We report the construction and characterization of a comprehensive magnonic-opto-electronic oscillator (MOEO) system based on 1550-nm photonics and yttrium iron garnet (YIG) magnonics. The system exhibits a rich and synergistic parameter space because of the ability to control individual photonic, electronic, and magnonic components. Taking advantage of the spin wave dispersion of YIG, the frequency self-generation as well as the related nonlinear processes becomes sensitive to the external magnetic field. Besides being known as a band-pass filter and a delay element, the YIG delay line possesses spin wave modes that can be controlled to mix with the optoelectronic modes to generate higher-order harmonic beating modes. With the high sensitivity and external tunability, the MOEO system may find usefulness in sensing applications in magnetism and spintronics beyond optoelectronics and photonics.
Differential algebraic fast multipole-accelerated boundary element method for nonlinear beam dynamics in arbitrary enclosures
Not Available
Structure and Dynamic and Nonlinear Optical Properties of Hg{sub 2}F{sub 2} Crystals
The structure of the Hg{sub 2}F{sub 2} compound was studied experimentally and theoretically within the density functional theory. X-ray diffraction studies enabled us to determine the space group of the crystal (I4/mmm), and the comparison of the experimentally obtained Raman spectra of these crystals with the theoretical ones enabled us to find and uniquely identify all bands in the spectra. The stability of the I4/mmm phase was analyzed in a wide range of uniaxial and hydrostatic pressures. It is shown that the uniaxial compression of a crystal along a tetrad axis results in a phase transition to the Cmcm structure at P{sub c} = 8 GPa, whereas the hydrostatic compression results in a previously unknown phase transition to the Cmca phase at P{sub c} = 9 GPa. The calculations of the cubic nonlinear susceptibility of Hg{sub 2}F{sub 2} predict a giant value of this quantity.
A golden probe of nonlinear Higgs dynamics
Not Available
Dynamic and nonlinear properties of epitaxial quantum dot lasers on silicon for isolator-free integration
Not Available
Beam manipulation techniques, nonlinear beam dynamics, and space charge effect in high energy high power accelerators
We had carried out a design of an ultimate storage ring with beam emittance less than 10 picometer for the feasibility of coherent light source at X-ray wavelength. The accelerator has an inherent small dynamic aperture. We study method to improve the dynamic aperture and collective instability for an ultimate storage ring. Beam measurement and accelerator modeling are an integral part of accelerator physics. We develop the independent component analysis (ICA) and the orbit response matrix method for improving accelerator reliability and performance. In collaboration with scientists in National Laboratories, we also carry out experimental and theoretical studies on beam dynamics. Our proposed research topics are relevant to nuclear and particle physics using high brightness particle and photon beams.
Neural Network Ensemble With Embedded Hamiltonian Constraints for Modeling Nonlinear Structural Dynamics.
Abstract not provided.
Extending relevance vector machine to resolve overtting during Bayesian calibration in nonlinear stochastic dynamics.
Abstract not provided.