Krylov V.V., Georgiev V.B., Jensen K.A. «Numerical and experimental modelling of structure-borne aircraft interior noise» Noise Theory and Practice (Электронный ресурс), 3, № 2, с. 2-16 (2017)

The problem of structure-borne interior noise generated in an aircraft cabin has been considered using a simplified reduced-scale model of a passenger aircraft. Experimental investigations included measurements of frequency response functions at several positions of a microphone inside the aircraft, when an electromagnetic shaker exciting structural vibrations was located at different places. Numerical investigations have been carried out as well, and they included finite element calculations of structural and acoustic modes as well as frequency response functions for interior acoustic pressure. Some of the obtained numerical results have been compared with the experimental ones. The observed reasonably good agreement between them indicates that structure-borne interior noise in the described reduced-scale aircraft model can be predicted and understood rather well. This demonstrates that the proposed approach employing simplified reduced-scale structural models can be used successfully for prediction and mitigation of aircraft interior noise.

Gorobey N.N., Lukyanenko A.S., Svintsow M.V. «On the initial state of the universe in the theory of inflation» Научно-технические ведомости Санкт-Петербургского государственного политехнического университета. Физико-математические науки, 10, № 1, с. 115-122 (2017)

A toy quantum model of the inflationary universe is considered in which the role of cosmic time is played by the inflaton scalar field (its logarithm). Based on a variant of the positive energy theorem in General Relativity for the case of a closed universe, a strictly positive energy of space is introduced. The principle of minimum of the energy of space is proposed which determines a ground state as well as the excited states of the universe in quantum cosmology. According to this principle, the Beginning of the universe does exist as a state of minimal excitation of the energy of space. The initial proto-inflation quantum state of the universe is defined as a state of minimal excitation of the energy of space provided that the potential energy of the inflaton scalar field is large at the Beginning. Simultaneously, quanta of space energy excitation are introduced and the expansion of the universe can be considered as the birth of these quanta. Quantum birth of the ordinary matter becomes significant when the potential energy of the inflaton scalar field comes down to zero value.

Malytskyy D., Pavlova A., Grytsai O., Astashkina O., Obidina O.O., Makhnitskyy M.P., Kozlovskyy E. «Models of seismic sources» Геоинформатика (Геоінформатика, укр.), № 3, с. 14-23 (2016)

Purpose. The paper proposes new methods to determine the parameters of the point and the extended sources of earthquakes. Design/methodology/approach. The source mechanism of an earthquake is determined by a graphic method from polarities of the P-waves first arrival, emergence angles (or angles of incidence) of the first P-waves at the stations, and station azimuths. The accuracy of the nodal planes on the focal sphere in the graphic method is significantly improved by accounting for important additional information contained in fuzzy P-wave arrivals and the logarithm of S- to P-wave amplitude ratio. Emergence angles of P-waves at the stations, and station azimuths are calculated using a software package for each of the events. In case of an insufficient number of stations, we propose an earthquake mechanism to determine by inversion only waveforms of direct P-waves at the stations. Findings. The inversion method consists in determining seismic moment tensor at a station and subsequently translating the solution into the event’s hypocenter. The extended source is modeled by solving the inverse problem as a set of point sources and their parameters. The problem of the earthquake source is therefore solved in two steps: 1) identification of source mechanism; 2) determination of slip, rise time, and rupture time for each of the elementary point sources. Correctness of the problem is improved by adding a constraint on the horizontal component of wave number. Practical value /implications. Using the data from the project SIV, we present practical application of the methods to determine both the point and the extended sources.