Gravitational instability and the formation of planetary systems of solar-type stars

The fundamental principles of the protoplanetary ring model – the model of formation of planetary systems of stars, which is based on the origin and development of large-scale gravitational instabilities (protoplanetary rings) – are extended to the formation of regular planetary satellites. Based on these principles, a complete model of the formation of planetary systems, including their satellites, (model of gas and dust rings) for solar-type stars is proposed.

On the use of a cell-centered finite-volume scheme on prismatic meshes in boundary layers

We consider the cell-centered finite-volume scheme with the quasi-one-dimensional reconstruction and generalize it to anisotropic prismatic meshes suitable for high-Reynolds-number problems. We offer a new algorithm of flux computation based on the reconstruction along the wall surface, whereas in the original schemes it was along the tangent to the wall surface. We also study how does the curvature of mesh elements influence the accuracy if taken into account.

Review of space vehicle control and guidance methods at atmosphere reentry

Review of control methods for statically stable reentry vehicles with low lift-to-drag ratio at returning from the Moon is presented. We are considering algorithms that have been used in Soviet and American Moon programs, as well as advanced algorithms that now are developed. General trends of advanced domestic and foreign methods are determined.

On self-correcting logic circuits of unreliable gates

The following statements are proved: 1) for any integer m ≥ 3 there is a basis consisting of Boolean functions of no more than m variables, in which any Boolean function can be implemented by a logic circuit of unreliable gates that self-corrects relative to certain faults in an arbitrary number of gates; 2) for any positive integer k there are bases consisting of Boolean functions of no more than two variables, in each of which any Boolean function can be implemented by a logic circuit of unreliable gates that self-correct relative to certain faults in no more than k gates; 3) there is a functionally complete basis consisting of Boolean functions of no more than two variables, in which almost no Boolean function can be implemented by a logic circuit of unreliable gates that self-correct relative to at least some faults in no more than one gate.

Comparative analysis of the geometrized histogram method and the neural network method for road markings recognition

This paper compares two approaches to determining road markings from video sequences, namely, the method of finding the markings using geometrized histograms and the method based on neural networks. An independent open dataset TuSimple is used to conduct a comparative analysis of the algorithms. Since the investigated methods have different architectures, their work is evaluated according to the following metrics: Accuracy, speed (relative FPS), general computational complexity of the algorithm (TFlops).

Extra investigation of the self-organized critical Manna model at higher critical dimension

I investigate the nature of the upper critical dimension for isotropic conservative sandpile models and calculate the emerging logarithmic corrections to power-law distributions. I check the results experimentally using the case of Manna model with the theoretical solution known for all statement starting from the two-dimensional one. In addition, based on this solution, I construct a non-trivial super-universal indicator for this model. It characterizes the distribution of avalanches by time the border of their region needs to pass its width.

Modelling of nozzle start-up for underexpanded jet generation

A numerical simulation of hydrogen jet in the micronozzle is carried out, which is used as the main element in the experimental installation to study the properties of rarefied gases at high speeds and low temperatures. The features of the transient jet flow - pressure gradients, velocities and the complex geometry of the problem are uniformly described within the framework of the quasi-gas dynamic algorithm included in the open platform OpenFOAM.

Direct tensor filter method for synthetic turbulent field generation

A Direct Tensor Filter Method for synthetic turbulent field generation is proposed in this paper. The method is a generalization of the Direct Anisotropic Filter Method. The turbulent velocity fields built on the base of this method provides more properties corresponding to real physical turbulent fields in comparison to ones obtained with help of DAF method.

On invariant finite-difference schemes for equations of one-dimensional flows of a polytropic gas for problems with spatial symmetries

One-dimensional polytropic gas dynamics equations for plane, radially symmetric, and spherically symmetric flows are considered. Invariant properties of equations are discussed, local conservation laws are derived. Additional conservation laws are written, which take place only in case of special values of adiabatic exponent. Classical difference scheme of Samarsky-Popov for gas dynamics has all difference analogs of conservation laws, except for additional ones. In difference schemes additional conservative laws take place in case of special state equation approximation. Scheme of Samarsky-Popov with special state equation was initially suggested by V.A. Korobitsyn. He described it as ‘thermodynamically consistend’ In current paper group properties, and conservation laws of thermodynamically consistent schemes are discussed, and numerical implementation for plane, cylinder, and spherical flows is perfomed.

Study of pulsating flows of ionizing hydrogen in the plasma accelerator based on two-dimensional model

Numerical study of the hydrogen ionization process in the channel of the quasi-stationary plasma accelerator is presented. Calculations of pulsating and stationary flows of ionizing hydrogen were carried out within the framework of two-dimensional MHD model in the approximation of local thermodynamic equilibrium, taking into account the radiation transport and under the condition of uniform gas supply at the channel inlet. As a result of a series of calculations, the empirical condition for the stationarity of axisymmetric flows of ionizing hydrogen was determined.