Investigation of the process of strong acoustic signal propagation in a layered environment of ice-water-bottom

A mathematical model was developed to calculate acoustic wave in a shallow sea under an ice layer for low frequency signals of 40-150 Hz. An experimental unit was developed by the authors on the basis of a low-frequency piston-type electrodynamic radiator which is capable of making experiments in layered environment. The experiments show satisfactory agreement with theoretical investigations. The peculiarities of wave propagation at water-ice boundary are under investigation. The developed models may be applied for new engineering systems for earthquake forecast when installing receiving systems in an ice layer

Experimental investigations of acoustic field in sea shelf zone

Developed experimental facility allows one to generate acoustic pressure within the intervals from 105 to 106 Pa with an affective system of matching layers of bottom, water and ice. Theoretical and experimental investigations showed the possibility of information transfer in a shallow sea under an ice layer. Experimental acoustic system allows one to make measurements in a wide frequency range from 40 to 1100 Hz. The conducted investigation can be used to develop effective remote communication and to model earthquake acoustic precursor measurements

Complex magnetic ordering as a driving mechanism of multifunctional properties of Heusler alloys from first principles

First-principles calculations are used to study the structural, electronic and magnetic properties of (Pd, Pt)-Mn-Ni-(Ga, In, Sn, Sb) alloys, which display multifunctional properties like the magnetic shapememory, magnetocaloric and exchange bias effect. The ab initio calculations give a basic understanding of the underlying physics which is associated with the complex magnetic behavior arising from competing ferro- and antiferromagnetic interactions with increasing number of Mn excess atoms in the unit cell. This information allows to optimize, for example, the magnetocaloric effect by using the strong influence of compositional changes on the magnetic interactions. Thermodynamic properties can be calculated by using the ab initio magnetic exchange parameters in finite-temperature Monte Carlo simulations. We present guidelines of how to improve the functional properties. For Pt-Ni-Mn-Ga alloys, a shape memory effect with 14% strain can be achieved in an external magnetic field