[en] In a number of astrophysical systems, the magnetic field, instead of varying over a scale comparable with the ''natural'' scale of the object (e.g., tens of thousands of kilometers in the case of the solar convective zone), varies over lengths that are orders of magnitude less than this (e.g., over distances down to 100 km in the case of the magnetic filaments detected in the upper part of the solar convective zone and probably present in much deeper layers). Therefore, the study of the propagation of magnetohydrodynamic (MHD) waves in plasmas with fine magnetic nonuniformities is of considerable general importance for astrophysics. We have developed a general formalism that allows one to treat the propagation of large-scale MHD waves in a finely stratified medium. We demonstrate that the presence of a fine structure of the plasma may produce considerable modifications of the modes existing in a uniform plasma, with a number of propagation modes that may even increase. We also show that the slow MHD mode may experience a collisionless damping, which causes the wave energy to be converted into the energy of the peristaltic modes of the plasma ''resonant'' layers. (c) 2000 The American Physical Society

No abstract available

[en] A detailed numerical simulation studying certain aspects of turbulence in the electron magnetohydrodynamic (EMHD) model is presented. In particular, new studies have been carried out in a parameter regime where the typical turbulent length scales are comparable to or smaller than the electron skin depth. This is the regime where the EMHD turbulence has similar traits to the hydrodynamic turbulence and the wave propagation effects due to whistlers are believed to be inconsequential. (c) 2000 American Institute of Physics

[en] A method is described for measuring the magnetorheological characteristics of ferrosuspensions by means of a capillary rheometer by use of measurement section in the form of a helix. This configuration permits liberal variation of the fundamental technical characteristics (diameter and length of the capillary) while imparting overall dimensions to the measurement section such that practical homogeneous magnetic field patterns can be utilized. It is noted that because of the orientation effect, the viscosity of the ferrosuspension in the inlet and exit ducts will be much smaller than the viscosity in the working section, thereby enhancing the measurement accuracy and simplifying the measurement of the pressure differential. Principal measurement errors associated with the proposed experimental scheme are analyzed. 6 references

No abstract available

[en] Short communication

[en] The MHD flow with aligned fields at infinity past a body in the far wake approximation is considered. In the case where two wakes, upstream and downstream, are present, by studying them separately (resp. as a coupled system) they are unstable (resp. stable) for both steady and unsteady small perturbations

[en] The effect of the general symmetry conditions on the signal is analyzed for all the vectors (the magnetic induction B, the weight W, and the velocity v) that determine the flowmeter signal. Such an analysis allows one to do the following: study the information content of the signal and note ways in which the applicability of the MHD method of converting the flow rate of a fluid into an electrical signal can be broadened; analyze the errors in the flowmeter signal caused by the flow structure; and give well-reasoned recommendations for the improvement of the information content of the flowmeter signal. 10 references

[en] Short communication

No abstract available