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Composites PVA/Graphite/CoFe1.97Ce0.03O4 and PVA/CoFe1.97Ce0.03O4 were synthesized and studied. The morphology and structure of the starting materials and composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS) and infrared spectroscopy (IR). The magnetic parameters were measured using a vibrating magnetometer. The absorptive capacity of the obtained materials was evaluated based on the results of measuring the transmission and reflection coefficients using a scalar network analyzer in the range of 8–12 GHz. The results show that the absorption characteristics of the PVA/Graphite/CoFe1.97Ce0.03O4 composite are significantly higher than those of the PVA/CoFe1.97Ce0.03O4 composites. Effective absorption is observed for the PVA/Graphite/CoFe1.97Ce0.03O4 composite in the frequency range of 8–12 GHz and corresponds to −25.08 dB mm−1, which indicates excellent absorption characteristics of electromagnetic radiation in this frequency range.

Preseismic intensification of fracturing has been investigated from occurrence analysis of seismo-acoustic pulses (SA foreshocks) and ULF magnetic pulses (ULF foreshocks) observed in Karimshino station in addition to seismic foreshocks. Such analysis is produced for about 40 rather strong and nearby isolated earthquakes during 2 years of recording. It is found that occurrence rate of SA foreshocks increases in the interval (-12, 0 h) before main shock with 3-times exceeding of background level in the interval (-6, -3 h), and occurrence probability of SA foreshocks (pA~75%) is higher than probability of seismic foreshocks (ps~30%) in the same time interval.ULF foreshocks are masked by regular ULF activity at local morning and daytime, nevertheless we have discovered an essential ULF intensity increase in the interval (-3, +1 h) at the frequency range 0.05-0.3 Hz. Estimated occurrence probability of ULF foreshocks is about 40%. After theoretical consideration we conclude: 1) Taking into account the number rate of SA foreshocks, their amplitude and frequency range, they emit due to opening of fractures with size of L=70-200 m (M=1-2); 2) The electro-kinetic effect is the most promising mechanism of ULF foreshocks, but it is efficient only if two special conditions are fulfilled: a) origin of fractures near fluid-saturated places or liquid reservoirs (aquifers); b) appearance of open porosity or initiation of percolation instability; 3) Both SA and ULF magnetic field pulses are related to near-distant fractures (r

The cable-suspension method is used to simulate weightlessness on Earth in the general case. By an example of mathematical simulation of a system of rigid bodies connected via hinged joints and suspended from a special facility, it is shown that the method developed provides realistic simulation of orbital processes under earth conditions. The validation criterion for the simulation is the closeness of the values of the forces and moments in joints and the attitude and angular velocities to their theoretical values in orbital motion. Some methods for the simulation of weightlessness conditions on Earth are known: free falling, an airplane flying along a parabolic trajectory, and a pool. Each of these methods has advantages and shortcomings. A method for simulating the weightlessness of a transformable spacecraft is also known. In this case, the spacecraft elements are suspended by cables from points movable in a horizontal plane. This method allows simulating only plane motions of the main module arising in changing the geometry of the spacecraft. If the reconfiguration of an orbiting spacecraft causes the spatial rotation of the ma in module, then the existing cable-suspension methods are inapplicable. Here, we consider the cable-suspension method as applied to precisely this general case. By mathematically simulating the behavior of a system of solids connected via hinged joints and suspended from a special facility, it is shown that the method developed provides realistic simulation of orbital processes under earth conditions. As a validation criterion for the simulation, we check how close the values of the forces and moments in joints and the orientation angles and angular velocities are to the analogous theoretical values in orbital motion. Within the framework of analytical mechanics, a rigorous mathematical model of the facility, including the object under investigation, was created. It allows us to accumulate a great body of data on the spacecraft dynamics. An analysis of the behavior of a system of bodies spatially rotating under the action of some perturbing factors in the laboratory environment allowed us to establish the operational reliability of the simulation technique proposed and its low sensitivity to various perturbations. The problem of simulating weightlessness conditions on Earth for spacecraft of variable (in order to change over from the transportable to operational state) configuration arose simultaneously with spacecraft themselves. A technique is known for simulation of these conditions at a ground laboratory for objects changing their geometry through the elastic vibrations of their structural elements. Certain structural elements are suspended by cables and springs from fixed supports [3]. A shortcoming of this and other known methods and facilities is that they allow modeling only the plane motion of structural elements. In the overwhelming majority of cases, the motion of actual space systems is spatial. This is because the spacecraft and all its separate elements execute complex spatial motion about the center of mass under the internal forces that ensure the reconfiguration. The angular motion of a spacecraft and the weightlessness state simulated under plane-motion conditions are far from real. Such a technique allows us to simulate the motion of an object only in the internal degrees of freedom, transforming relative motion to absolute motion. The new weightlessness simulation technique considered here implies simulation of the motion of a spacecraft not only in internal but also in three external angular degrees of freedom.

The experimental results have shown possibility to detect signal of plexiglass cylinder situated behind plexiglass slab using multifrequency measurements with synthesizing of 2-D spatial images. This approach has advantages in comparison with single-frequency method.

1D inverse problem for multilayered dielectric structures is induced by different applications. The constancy of every layer parameters is given. This situation corresponds to the partial-constant profile of permittivity. The problem is to estimate values of dielectric constants and thickness of every layer simultaneously with only one-side access, thus only reflection coefficient (RC) information can be used.