Том 64, № 1 (2019)

A mechanism of laser radiation absorption by a metal surface during the formation of surface nanostructures is proposed. The mechanism is based on the heterogeneous character of such absorption due to the formation of absorption zones in the old excited structure. It has been shown that the process of laser radiation absorption by metals can be of a nonlinear character.

It is shown that the boundary-value problem for a layered medium with parallel multiple cavities is reduced to the Riemann vector problem. To solve it, a factorization method is developed, which makes possible to construct the solution to be built in arbitrary approximations.

The trajectories of a mission to an asteroid with the presence of a spacecraft (SC) near the asteroid for some time and including a return to the Earth have been studied. A two-stage method of constructing optimum (with respect to the maximum of the useful SC mass) interplanetary trajectories for an Earth–asteroid–Earth mission with high thrust engines has been developed: in the central Newtonian field of the Sun’s attraction at the first stage and with allowance for perturbations at the second stage. An algorithm of constructing conjugate functions for the case of maximizing the useful mass has been designed. The optimum trajectories for the Earth–Apophis–Earth mission have been constructed and analyzed. The possibility in principle of organizing the Earth–Apophis–Earth space mission based on the Soyuz and Zenit launch vehicles and Fregat upper stage for a flight in 2019–2022 has been demonstrated.

An adaptive, semi-analytical, and geometrically clear method for synthesis of sequences of Venusian gravity-assist maneuvers setting the desired inclination of a spacecraft orbit is proposed. The geometric constraint on the maximum possible inclination of a spacecraft orbit, which depends on the asymptotic spacecraft velocity relative to Venus, and the dynamic constraint (arising when a gravity-assist maneuver is performed) on the angle of rotation of the vector of asymptotic velocity relative to Venus are considered simultaneously.

The effect of a significant and sharp loss of the average traction force upon vehicle acceleration during asymmetric or asynchronous vibrations of the driving wheels is found. The effect manifests itself in vehicles with an interwheel differential under an intensive start with slip. The vibrational modes leading to both partial and almost complete loss of the average traction force are specified. It can be dangerous when driving on highways or crossing unregulated intersections.

Using numerical models, we have studied what depth of the outer layer the comet nuclei are degassed to when they are in orbits whose perihelion is close to the Sun for tens of years. The problem is topical, because it helps to understand how much the experimentally obtained results on the composition of comet comas depend on how long the comet is in its present-day orbit and how adequately the data obtained reflect the composition of comet nuclei as a whole. The proposed approach, which is demonstrated using comet 67P/Churyumov-Gerasimenko as an example, is based on a 3D comet nucleus surface relief model and takes into account not only its orbital motion, but also its diurnal rotation. The propagation of heat in the nucleus subsurface layers is described by a 1D heat conduction equation for a porous rock-ice composition of matter. Based on this approach, we have derived the temperature distributions in the subsurface layers for several surface patches located in the Ma’at region in 20 revolutions around the Sun, ~130 years.

The influence of the climate change in Russia on the operation of hydroelectric power plants during the 21st century is considered. For obtaining quantitative assessments, the results yielded by global climatic models for river runoff were subjected to ensemble averaging. In addition to the standard RCP climatic scenarios, the MPEI scenario is considered, the fundamental distinctive feature of which is that the most likely development trajectories are selected. It is found that the choice of a scenario has an essential effect on both the qualitative pattern of river runoff changes over the territory and on the quantitative characteristics of this process. An integral assessment for the change in the hydroelectric power plant outputs due to climate change is made.