Modelling of Ultrasonic Concentrators for Processing of Volume Nanostructured Materials

Abstract

The article is devoted to studying of stress and displacement amplitude distribution in ultrasonic concentrators of different forms. The modelling of different forms of ultrasonic concentrators was considered in detail that allowed to choose an optimal form of concentrator providing maximum amplitude of vibrational speed and uniform stress amplitude distribution across the concentrator section. The modelling was carried out for purpose of the subsequent application of ultrasonic treatment to nanostructured materials. Numerical calculation in the environment of MatLab is carried out and diagrams of dependences of stress and displacement amplitude distribution of conic, exponential, ampoule and two-ampoule forms of concentrators are constructed. Visual distribution models of stresses on the section of concentrators and elastic displacements of material in samples of these forms are constructed, resonance frequencies of longitudinal fluctuations of ultrasonic half-wave concentrators are found in the program Abaqus complex.

On the Durability of Concrete under the Action of Ultra-Low (up to -196 °C) Technological Temperatures

“…Taking into account the above results of the physical-chemical bases of concrete resistance to the cyclic exposure of cryogenic temperatures development, it can be recommended in relation to the production technology of normal weight concrete with use of dense natural aggregates (which according to the works [2,12,15,17] clearly inferiors by the frost resistance indicators to equally strong structural lightweight concretes on porous aggregates) the following: -the use of chemical and mineral admixtures, modifying the structure of concrete in the direction of the communicating capillary pores minimum content and respectively with a predominance of closed small pores in hardened cement gel; -sulphate-resistant Portland cement is recommended for use in massive reinforced concrete structures of engineering constructions, in particular in LNG reservoirs foundations, as well as in massive structures of floating terminals intended for transporting tanks filled with LNG to gas carriers ships, especially operated in the conditions of the Northern tidal seas.…”

Synthesis of 5-Hydroxymethylfurfural-Acetone Resins

“…However, the condensation products of 5-HMF and acetone were studied only from the point of view of their processing into diesel fuel [9,12]. Therefore, it is advisable to study oligomers based on 5-HMF and acetone and evaluate the prospects for producing thermosetting polymers and composite materials based on them.…”