[en] It is shown that Ward's two-monopole ansatz possesses a non-linear (twisted) generalization of axial symmetry, and this symmetry is used to show that, for any finite value of the intrinsic parameter, the ansatz describes separated monopoles and is non-singular everywhere if it is non-singular on one of the coordinate planes. (orig.)

No abstract available

No abstract available

[en] By considering suitable axially symmetric slices on the Kruskal spacetime, we construct a counterexample to a recent version of the Penrose inequality in terms of so-called generalized apparent horizons. (fast track communication)

[en] The instances of vortex ring evolving in confined domains is observed in biological and engineering flows. The evolution of a vortex ring inside a non-axisymmetric confinement and the effect of this confinement on the decay of the ring is investigated in this paper. A square confinement is chosen for this purpose. The effect of confinement ratio (CR), defined as the ratio of the diameter of vortex ring to the size of confinement, is studied in detail. The asymmetry caused by the confinement on the ring is noted by measuring its properties on two different planes, namely the Y-plane and the diagonal plane. The asymmetry on the vortex ring is qualitatively observed to be dependent on CR. (paper)

[en] The field enhancement factor at the emitter tip and its variation in a close neighbourhood determines the emitter current in a Fowler–Nordheim like formulation. For an axially symmetric emitter with a smooth tip, it is shown that the variation can be accounted by a $\cos \tilde{\theta }$ factor in appropriately defined normalized co-ordinates. This is shown analytically for a hemiellipsoidal emitter and confirmed numerically for other emitter shapes with locally quadratic tips.

[en] We give sufficient conditions for the rigid body in the presence of an axisymmetric force field and a gyroscopic torque to admit a Hamilton-Poisson formulation. Even if by adding a gyroscopic torque we initially lose one of the conserved Casimirs, we recover another conservation law as a Casimir function for a modified Poisson structure. We apply this frame to several well-known results in the literature. -- Highlights: → Gyroscopic torques and sufficient conditions for a Hamilton-Poisson formulation. → An algorithm to find a third constant of motion as a Casimir function. → A unitary framework that encompasses well-known gyroscopic torques from literature.

[en] The advantages and disadvantages of induction heating by high-frequency currents during large-sized parts mounting and dismounting are studied. The deviations of the temperature field and the deformation field of the part from the axial symmetry with the horizontal position of the shaft are analyzed. Recommendations were developed on how to take into account these deviations in the technology of mounting and dismounting of the retaining rings of turbogenerators. (paper)

[en] This paper is concerned with eddy-current (EC) nondestructive testing of conductive materials and focuses, in particular, on extending the well-known linear sampling method (LSM) to the case of EC equations. We first present the theoretical foundation of the LSM in the present context and in the case of point sources. We then explain how this method can be adapted to a realistic setting of EC probes. In the case of identifying the shape of external deposits from impedance measurements taken from inside of the tube (steam generator), we show how the method can be applied to measurements obtained from a sweeping set of coils. Numerical experiments suggest that good results can be achieved using only a few coils and even in the limiting case of backscattering data. (paper)

[en] A graphical method for the analysis of relaxation data is presented. It allows a fast estimation of the range of values of the components of the axially symmetric rotational diffusion tensor that are compatible with the experimental relaxation data. The graphical method clearly shows the contribution of different experimental relaxation parameters to the measured anisotropy. In particular, for proteins with moderate anisotropy, data from at least two N-H bonds forming angles close to 0 deg. and 90 deg. with respect to the principal axis of the rotational diffusional tensor are needed. For very anisotropic systems, combination of different relaxation parameters from a single residue is enough to characterize the local anisotropy