Search results for "oscillation"
showing 10 items of 1257 documents
Second-order optical phase transition in a semilinear photorefractive oscillator with two counterpropagating pump waves
2002
Soft-mode onset of coherent oscillation is revealed in a semilinear cavity with two counterpropagating pump waves. From the dynamics of the oscillation intensity and the dynamics of the grating decay with the feedback applied, critical behavior is detected: Both the characteristic time of oscillation onset and grating decay time go to infinity exactly at the threshold coupling strength. A conclusion is made about the similarity of this type of oscillator to the second-order phase transition.
Acoustic Wave Properties in Footpoints of Coronal Loops in 3D MHD Simulations
2021
Acoustic waves excited in the photosphere and below might play an integral part in the heating of the solar chromosphere and corona. However, it is yet not fully clear how much of the initially acoustic wave flux reaches the corona and in what form. We investigate the wave propagation, damping, transmission, and conversion in the lower layers of the solar atmosphere using 3D numerical MHD simulations. A model of a gravitationally stratified expanding straight coronal loop, stretching from photosphere to photosphere, is perturbed at one footpoint by an acoustic driver with a period of 370 seconds. For this period acoustic cutoff regions are present below the transition region (TR). About 2% …
A dynamical dark energy model with a given luminosity distance
2011
It is assumed that the current cosmic acceleration is driven by a scalar field, the Lagrangian of which is a function of the kinetic term only, and that the luminosity distance is a given function of the red-shift. Upon comparison with Baryon Acoustic Oscillations (BAOs) and Cosmic Microwave Background (CMB) data the parameters of the models are determined, and then the time evolution of the scalar field is determined by the dynamics using the cosmological equations. We find that the solution is very different than the corresponding solution when the non-relativistic matter is ignored, and that the universe enters the acceleration era at larger red-shift compared to the standard $\Lambda CD…
Temporal and spatial persistence of combustion fronts in paper
2003
The spatial and temporal persistence, or first-return distributions are measured for slow-combustion fronts in paper. The stationary temporal and (perhaps less convincingly) spatial persistence exponents agree with the predictions based on the front dynamics, which asymptotically belongs to the Kardar-Parisi-Zhang universality class. The stationary short-range and the transient behavior of the fronts are non-Markovian, and the observed persistence properties thus do not agree with the predictions based on Markovian theory. This deviation is a consequence of additional time and length scales, related to the crossovers to the asymptotic coarse-grained behavior. Peer reviewed
Physics potential of the Jiangmen underground neutrino observatory
2019
JUNO (Jiangmen Underground Neutrino Observatory) is a 20 kton multipurpose neutrinodetector under construction in China and it will be completed in 2021. The detector will belocated near the the city of Jiangmen, 53 km away from two nuclear power plants that willprovide the neutrino flux for the main sear of the observatory. The main physics goal is the determination of the neutrino Mass Hierarchy, even if will play animportant also in other topics, such as: neutrino oscillation, solar neutrino, SuperNova neutrinos,geoneutrinos and atmosperic neutrinos among others
A Very Large Area Telescope for γ-Ray Astronomy Above 100 MeV Employing Limited Streamer Tubes
1994
A new detector for γ-ray astronomy above 100 MeV is described in which the electron-positron pairs are tracked by means of a set of plane arrays of Limited Streamer Tubes. This technique allows to build up very large area experiments which are specifically useful to study variable or transient sources.
Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector
2003
Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon-neutrinos, as predicted from, e.g., the sum of all active galaxies in the universe. This search yielded no excess events above those expected from the background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux. For an assumed E^-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E^2 Phi(E) = 8.4 x 10^-7 GeV cm^-2 s^-1 sr^-1 (for a predominant neutrino energy range 6-1000 TeV) which is the most restrictive bound placed by any neutrino detector. When specific predicted spectral…
Nonstationary oscillations in gyrotrons
2001
The onset of stochastic oscillations in gyrotrons is studied by means of the self-consistent theory describing nonstationary processes. Complicated alternating sequences of regions of stationary, automodulation, and chaotic oscillations are found in the plane of the generalized gyrotron variables: cyclotron resonance mismatch and dimensionless current. The results of the investigations are important in connection with attempts to increase the output power of gyrotrons by raising the current.
Three dimensional dynamics of ferromagnetic swimmer
2011
It is shown that a flexible ferromagnetic filament self-propels perpendicularly to the AC magnetic field during a limited period of time due to the instability of the planar motion with respect to three dimensional perturbations. The transition from the oscillating U-like shapes to the oscillating S-like shapes is characterized by the calculated Wr number.
Resolution of Single Spin Flips of a Single Proton
2013
The spin magnetic moment of a single proton in a cryogenic Penning trap was coupled to the particle's axial motion with a superimposed magnetic bottle. Jumps in the oscillation frequency indicate spin-flips and were identified using a Bayesian analysis.