A linear stability analysis has been performed onto a self-gravitating magnetized gas disk bounded by external pressure. The resulting dispersion relation is fully explained by three kinds of instability: a Parker-type instability driven by self-gravity, usual Jeans gravitational instability and convection. In the direction parallel to the magnetic fields, the magnetic tension completely suppre...

In the lattice structure considered here, crack propagation is caused by feeding waves, carrying energy to the crack front, and accompanied by dissipative waves carrying a part of this energy away from the front (the di4erence is spent on the bond disintegration). The feeding waves di4er by their wavenumber. A zero feeding wavenumber corresponds to a macrolevel-associated solution with the clas...

We present an analysis of seismic noise recorded during 1995–2004 by a medium-aperture, short-period seismic array located in Chiang Mai, Thailand (CMAR). We calculated frequency-wavenumber spectra for nearly 1000 randomly selected time windows, each with a length of 160 sec. At frequencies above about 1.4 Hz the noise is unorganized and the wavenumber spectra are isotropic and diffuse; however...

The solution of reduction to the pole (RTP) of magnetic data in the wavenumber domain faces a long standing difficulty of instability when the observed data are acquired at low magnetic latitudes or at the equator. We develop a solution to this problem that allows stable reconstruction of the RTP field with a high fidelity even at the magnetic equator. The solution is obtained by inverting the ...

This paper presents a numerical study of high wavenumber coherent structure evolution in boundary layer transition flow using recently-developed high order Combined compact difference schemes with non-uniform grids in the wall-normal direction for efficient simulation of such flows. The study focuses on a simulation of an Adverse-Pressure-Gradient (APG) boundary layer transition induced by broa...

2 Abstract. A multiresolution optimal interpolation scheme is described and used to map the sea level anomaly of the Mediterranean Sea based on TOPEX/POSEIDON and ERS-1 data. The principal advantages of the multiresolution scheme are its high computational eeciency, the requirement for explicit statistical models for the oceanographic signal and the measurement errors, and the production of err...

We study the dual cascade scenario for two-dimensional turbulence driven by a spectrally localized forcing applied over a finite wavenumber range [kmin, kmax] (with kmin > 0) such that the respective energy and enstrophy injection rates and η satisfy k2 min ≤ η ≤ k 2 max . The classical Kraichnan–Leith–Batchelor paradigm, based on the simultaneous conservation of energy and enstrophy and the sc...

The Variational Boussinesq Model (VBM) for waves above a layer of ideal fluid conserves mass, momentum, energy, and has decreased dimensionality compared to the full problem. It is derived from the Hamiltonian formulation via an approximation of the kinetic energy, and can provide approximate dispersion characteristics. Having in mind a signalling problem, we search for optimal dispersive prope...

We consider the effective wave motion, at spectral singularities such as corners of Brillouin zone and Dirac points, in periodic continua intercepted by compliant interfaces that pertain to e.g. masonry fractured materials. assume Bloch-wave form scalar equation (describing anti-plane shear waves) a point departure, we seek an asymptotic expansion about reference wavenumber-frequency space usin...

INTRODUCTION Over the years, our research into turbulence at Edinburgh has concentrated on the application of renormalization methods to the prediction of the energy spectrum of isotropic turbulence. General discussions of this work will be found elsewhere (McComb 1990, 1995), while accounts of specific progress have been given previously in this conference series (McComb & Shanmugasundaram 198...