Vol 29, No 2 (2023)

In this work, a simple model of energy harvester transforming the energy of unsРисунок mechanical vibrations into useful electric energy is proposed. The mechanical part of the system is presented in the form of an inverted pendulum. The electric part consists of a converter of mechanical energy based on a direct piezoelectric effect, and a payload. The dynamics of the system is considered in the linearized production, the areas of stability are determined, various dynamics modes in the parameter space are identified. It was established that the stabilizing pendulum of management based on the principles of feedback allows you to transfer the system into a sРисунок mode of functioning. The optimal characteristics of the system that meets maximum power were found.

The research is devoted to the study of the stress field at the crack tip in an anisotropic material with three mutually orthogonal axes of symmetry of the fourth order (with cubic symmetry). A plane case is considered when one of the axes of symmetry is orthogonal to the cracked plate, and the remaining two axes lie in the plane of the plate. The paper presents an asymptotic analysis of the contribution of higher approximations in the generalized asymptotic decomposition of mechanical fields near the crack tip in a linearly elastic anisotropic material with cubic symmetry of its elastic properties. In the article, based on the obtained solution of M. Nejati and co-authors for an infinite anisotropic plate with a central crack, circumferential apportionments of the stress tensor components at the crack tip at various distances from the crack tip are constructed, which makes it possible to estimate the contribution of non-singular (regular) terms to the general asymptotic representation of mechanical fields generated by an acute crack. In the work of M. Nejati, the contribution of exclusively T-stresses is analyzed, then, as shown in this work, the terms following the T-stress play a significant role in describing the fields induced by the crack. A comparison of the angular distributions of the stress tensor components constructed at different distances from the crack tip indicates that with the increase of distances from the crack tip, it is required to preserve in asymptotic series representing stresses, displacements and strains near the tip of the crack, the terms of high order of smallness. The preservation of the terms of high order of smallness can be used to expand the domain in which the asymptotic solution in the series is valid.

In this paper, we prove the action of the compact group G defined by the stratified space X is continuous to the space Z(X) being a stratified space containing the self-stratified space X as a closed subset. An equivariant analogue of some results of R. Cauty concerning A(N)R(S) – spaces is proved. It is presented that the orbit space  Z(X)/G by the action of the group G is a S space.

The article considers the associated production of J/ψ -mesons and direct photons at the energy of the NICA collider, $\sqrt{s}$ = 27 GeV, in the Generalized Parton Model in the leading order of perturbation theory of the quantum chromodynamics. Hadronization of a pair of $c\overline{c}$-quarks to a J/ψ -meson is described in terms of two approaches: the color singlet model and the color evaporation model. Nonperturbative parameters of the models are fixed from comparison with the available experimental data on inclusive production of J/ψ -mesons obtained at energies from $\sqrt{s}$=19 up to $\sqrt{s}$=200 GeV. It is shown that the processes of the associative production of J/ψ+ γ can be used to study of gluon distribution functions depending on the transverse momentum in a proton.

In this work, we have studied the dynamics of entanglement of two identical superconducting qubits resonantly interacting with the one-mode field of a coplanar microwave cavity without loss through single-photon transitions in the presence of third- and fifth-order nonlinearities. Based on the solution of the equation of evolution of the system for the Fock initial states of the cavity field, the criterion of qubits entanglement – negativity is calculated. The results of the negativity calculation show that for the initial separable states, the cavity nonlinearity can lead to a significant increase in the maximum degree of qubit entanglement. It is shown that for the initial entangled states of qubits and intense cavity fields, taking into account nonlinearities leads to stabilization of the degree of entanglement of qubits in the cavity and contributes to the disappearance of the effect of the entanglement sudden death of qubits.