Photoacoustic effect in micro- and nanostructures: numerical simulations of Lagrange equations

The work provides the description of theoretical and numerical modeling techniques of thermomechanical effects that take place in absorbing micro- and nanostructures of different materials under the action of pulsed laser radiation. A proposed technique of the numerical simulation is based on the solution of equations of motion of continuous media in the form of Lagrange for spatially inhomogeneous media. This model allows calculating fields of temperature, pressure, density, and velocity of the medium depending on the parameters of laser pulses and the characteristics of micro- and nanostructures.

Estimation of the optimal frequency range of EM waves for the implementation of a wireless channel of charge activation during drilling and blasting operations

The article analyzes the methods of wireless detonation of underground charges during drilling and blasting operations. The technologies considered are intended mainly for disrupting the integrity of rocks during tunneling and extraction of mineral resources in mines and quarries, as well as for the controlled demolition of buildings. The methods presented in the scientific press do not provide sufficient accuracy of time synchronization between the moment of the explosion and the command to launch the operator of the explosive machine, which is a necessary requirement for seismic exploration, and are also based on the use of magnetic antennas for wireless activation of detonators located at a depth of 30 m. The article, by the authors, on the basis of the analytical solution of equations and computational modeling, considers the physical processes of propagation of electromagnetic fields and currents induced by a grounded electric dipole, which is an alternative method of transmitting radio signals to a linear group of detonators. The most favorable operating frequency range of the channel is also analyzed based on the absorbing properties of the medium.

Skewing of crane during acceleration

During the work of crane and during its driving on the crane track, the so-called skewing of the crane arises. The physical phenomenon of crane skewing has been interpreted in various ways in the past. This corresponded to various physical models of skewing, which were created by various authors and which were presented in the standards for the design of crane structures and tracks. Current standards define the skewing as the so-called oblique running of the crane along the track with uniform movement. This is a situation where the force on the front guide means returns the obliqued crane when driving to the straight position. Theoretical formulas for the calculation of forces caused by skewing during oblique running crane were determined by Hannover. These relationships apply to movement of the crane with constant velocity along the crane track. The author of the article derived a model of a crane, which allows to investigate the movement of the crane along the crane track in general, it means both during uniform movement and during its acceleration or deceleration. It is a dynamic model that allows the solution of equations of motion to solve the coordinates corresponding to the degree of freedom and, among other things, to determine the forces between the crane and the crane track. This article presents the results obtained from this model for a specific selected crane during its acceleration. The contact of the front guide wheel is assumed, which is in accordance with the model derived by Hannover and which is also stated in the currently valid standards.

Spherically symmetric AdS black holes with smeared mass distribution

In this paper, we study the thermodynamics properties of noncommutative NC (3 + 1)-dimensional in the spherically symmetric AdS black holes. The solution of equations of motion in AdS spacetime using a general distribution mass is studied. The results show that there exist AdS4 black holes only for the non-Gaussian distributions, while for the Gaussian distributions, Nariai numbers do not exist in case of small values of cosmological constant [Formula: see text] while Nariai numbers exist and tend to zero for large values of [Formula: see text]. Moreover, we show that there is an effect of [Formula: see text] on the Hawking temperature of black hole and this effect disappears when the Hawking temperature tends to zero. Finally, it turns out that the behavior of free energy does not change with the change of [Formula: see text], but its value increases with increasing [Formula: see text].

Exact plane-wave solution of equations of gravitation theory with massive graviton

The theory of gravitation with a massive graviton, which was proposed by Visser, is considered. The exact solution of this theory is found when the source of the gravitational field is plane scalar wave. The Hamilton-Jacobi method obtained the laws of motion of massive and massless particles in this gravitational field.