Mathematical Modeling of Complex Oscillations of Flexible Micropolar Mesh Cylindrical Panels

Russian Physics Journal - A new mathematical model of oscillations of mesh micropolar geometrically nonlinear cylindrical panels under the action of a normal alternating distributed load has been...     

Production of a Concentrate of Rare-Earth Metals from Wet-Process Phosphoric Acid

Desorption of rare-earth metals (REMs) (lanthanum, yttrium, and ytterbium), as well as iron and aluminum, from the KU-2 sulfocation exchanger phase with solutions of mineral acids and ammonium nitrate and sulfate of various concentrations was studied. New data on the distribution of REMs in these systems were obtained. It was found that it is the most rational to use an ammonium nitrate solution with concentration of 300 g L^–1. It is recommended to precipitate a concentrate of REMs from the resulting desorbate with ammonium carbonate, with the subsequent separation of the suspension by the electrofl otation method.     

Chaotic dynamics of flexible beams with piezoelectric and temperature phenomena

The Euler–Bernoulli kinematic model as well as the von Kármán geometric non-linearity are used to derive the PDEs governing flexible beam vibrations. The beam is embedded into a 2D temperature field, and its surface is subjected to action of the electric potential. We report how an increase of the exciting load amplitude yields the beam turbulent behavior, and how the temperature changes a scenario from a regular/laminar to spatio-temporal/turbulent dynamics. Both classical Fourier analysis and Morlet wavelets are used to monitor a strong influence of temperature on regular and chaotic beam dynamics.     

Routes to chaos in continuous mechanical systems: Part 2. Modelling transitions from regular to chaotic dynamics

In second part of the paper both classical and novel scenarios of transition from regular to chaotic dynamics of dissipative continuous mechanical systems are studied. A detailed analysis allowed us to detect the already known classical scenarios of transition from periodic to chaotic dynamics, and in particular the Feigenbaum scenario. The Feigenbaum constant was computed for all continuous mechanical objects studied in the first part of the paper. In addition, we illustrate and discuss different and novel scenarios of transition of the analysed systems from regular to chaotic dynamics, and we show that the type of scenario depends essentially on excitation parameters.     

Simulation of the lower boundary of an acoustic waveguide

The paper discusses simulation of the lower boundary of an acoustic waveguide. The applicability and relationship of rigid bottom and fluid half-space models are studied as a function of the bottom sediment parameters. The influence of bottom losses on the sound field characteristics in a waveguide is studied. Examples of numerical simulation are given.

     

Routes to chaos in continuous mechanical systems. Part 3: The Lyapunov exponents,hyper, hyper-hyper and spatial–temporal chaos

Third part of the paper is devoted to analysis of the hyper, hyper-hyper and spatial–temporal chaos of continuous mechanical systems using the Lyapunov exponents. The constructed algorithms for the Lyapunov exponents’ computation allowed detecting and analysing novel phase transitions from chaos through hyper chaos to hyper-hyper chaos. In addition, a novel characteristic “maximal deflection versus excitation amplitude” has been introduced to study stability properties of the investigated continuous systems. It should be emphasized that the latter characteristic yields results in full agreements with those obtained via the Lyapunov exponents’ spectrum estimation. The introduced methods and tools of analysis allowed detecting the Sharkovskii windows of periodicity in all continuous mechanical systems investigated in this paper. Finally, the approach to study the space-temporal chaos exhibited by shell structural-members is also proposed.     

Catalysts based on NaY zeolite for oxidative destruction of organic azo dyes in wastewater

Samples of catalysts containing Ag⁺ and Co⁺² cations were prepared on the basis of NaY granulated synthetic zeolite without binders by the ion-exchange method with the subsequent thermal treatment at 350–500°C. It was found that CoNaY samples are most catalytically active in the process of carmoisine oxidation by hydrogen peroxide in a weak alkaline medium (pH 8.5).     

Nanobeam Theory Taking Into Account Physical Nonlinearity

Russian Physics Journal - In this paper, we construct a new theory of nanobeams taking into account the dependence of the material properties on the stress state. The theory is based on the...     

The Sound Field in a Marine Waveguide with a Cylindrical Inhomogeneity

Acoustical Physics - A three-dimensional analytical solution is constructed for the model of an inhomogeneous hydroacoustic waveguide with a cylindrical inhomogeneity within the sedimentary layer....