The GOLF instrument, as its name implies, was designed to optimise the possibility of measuring low frequency oscillations, in the range of the g-modes and the lower p-modes. The high stability of the instrument , combined with a continuity of data close to 100 % has contributed to providing a velocity time series in which the instrumental noise is indeed extremely low. However, in the region o...

The calculated intermediate and high degree p-mode frequencies of standard solar models show greater disagreement with the observations than low degree modes. This leads to the conclusion that the subatmospheric structure of the models has to be improved. We are presenting solar models with up-to-date input physics and controlled numerical accuracy of 10 5. For the outer boundary condition we u...

Nonadiabatic effects associated with the transfer of energy and with turbulent stresses add small imaginary parts, wji> and w~2>, to solar p-mode eigenfrequencies. Numerical calculations have shown that these quite different processes make comparable contributions to W; at frequencies well below the acoustic cutoff at wac· We derive analytic expressions which reveal the connection between w~ 1 ...

Due to their high plasma frequencies, drifting semiconductor plasmas interacting with slow electromagnetic waves hold promise for terahertz amplifiers and oscillators. In these devices, the gain and the type of instabilities are influenced by electron collisions. To study the effect of collisions, we developed a two-wave model describing the interaction between drifting solid-state plasmas and ...

The so-called ”acoustic revival mechanism” of core-collapse supernova proposed recently by the Arizona group is an interesting new possibility. Aiming to understand the elementary processes involved in the mechanism, we have calculated the eigen frequencies and eigen functions for the g-mode oscillations of a non-rotating proto neutron star. The g-modes have relatively small eigen frequencies. ...

Tropical Storm Edouard (2002) experienced episodic outbreaks of convection downshear within the storm core in the presence of 11–15 m s of ambient vertical wind shear. These outbreaks lasted 2–6 h and were followed by long periods with no deep convection. Flights fromU.S. Air Force reconnaissance aircraft within the boundary layer were used to investigate the cause of one such oscillation. Low ...

Direct and large eddy simulations are performed to study the internal waves generated by the oscillation of a barotropic tide over a model ridge of triangular shape. The objective is to go beyond linear theory and assess the role of nonlinear interactions including turbulence in situations with low tidal excursion number. The criticality parameter, defined as the ratio of the topographic slope ...

We present a systematical analysis of uncertainties in the helioseismological determination of quantities characterizing the solar structure. We discuss the effect of errors on the measured frequencies, the residual solar model dependence and the uncertainties of the inversion method. We find Y ph = 0.238 − 0.259, R b /R ⊙ = 0.708 − 0.714 and ρ b = (0.185 − 0.199) gr/cm 3 (the index b refers to...

In this paper, Turbulent mixed convective heat transfer of water and Al2O3 nanofluid has been numerically studied in a horizontal tube under non-uniform heat flux on the upper wall and insulation in the lower wall using mixture model. For the discretization of governing equations, the second-order upstream difference scheme and finite volume method were used. The coupling of pressure and veloci...

Ultrathin films of cellulose nanocrystals (CNCs) are obtained by using a convective assembly setup coupled with a low-strength external AC electric field. The orientation and degree of alignment of the rod-like nanoparticles are controlled by the applied field strength and frequency used during film formation. Calculated dipole moments and Clausius-Mossotti factors allowed the determination of ...