This note considers variations on the theme of a solenoid magnet (i.e., a magnet whose field has axial symmetry) as a lens for charged particles. A related problem has been posed in [1]. Recall that if a device is to be a lens with optic axis along the z axis in a cylindrical coordinate system (r, φ, z), then as particles leave the device they must have no azimuthal momentum, Pφ = 0, and their ...

Solutions of partial differential equations with coordinate singularities often have special behavior near the singularities, which forces them to be smooth. Special treatment for these coordinate singularities is necessary in spectral approximations in order to avoid degradation of accuracy and efficiency. It has been observed numerically in the past that, for a scheme to attain high accuracy,...

The drag of two cylindrical intruders in a two-dimensional granular environment is numerically studied by the discrete element method. We find yield force, below which cannot move because interactions with surrounding particles. Above on other hand, can at constant speed. investigate relationship between force and steady speed intruders, where becomes higher as distance decreases. confirm that ...

The wall admittance of an arbitrarily shaped microstrip antenna is generally formulated. As examples, elliptical microstrip antennas with and without a circular slot are calculated. The wall admittance is determined by the spectral domain analysis in order to consider the effect of the dielectric substrate. The electromagnetic fields within the cavity are expanded in terms of the eigenfunctions...

In this paper, we study the dynamics of rotating Bose–Einstein condensates (BEC) based on the Gross–Pitaevskii equation (GPE) with an angular momentum rotation term and present an efficient and accurate algorithm for numerical simulations. We examine the conservation of the angular momentum expectation and the condensate width and analyze the dynamics of a stationary state with a shift in its c...

Invisibility devices based on coordinate transformation have opened up a new field of considerable interest. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely, serial inductors and shunt capacitors. Our experiment clearly shows that the a...

This work proposes the use of electrochemical cells (bipolar or series) like mechanism recuperate of impurities and noble species, from contaminated or impoverished electrolytes. The treated fluid circulates through porous or perforated electrodes of compound material. In order to produce successive, selective deposits of the different chemical substances, these electrodes are located spaced by...

We study quadratic integrability of systems with velocity dependent potentials in three-dimensional Euclidean space. Unlike the case only scalar potential, does not imply separability configuration The leading order terms pairs commuting integrals can either generalize or have no relation to forms separation absence a vector potential. call such generalized, distinguish them from standard ones,...

We study integrable and superintegrable systems with magnetic field possessing quadratic integrals of motion on the three-dimensional Euclidean space. In contrast case without vector potential, corresponding may no longer be connected to separation variables in Hamilton-Jacobi equation can have more general leading order terms. focus two cases extending physically relevant cylindrical- spherica...