Moscow University Mechanics Bulletin最新文献

The presented review consists of two parts. The first one is devoted to research generalizing the classical Prandtl problem in the case of taking into account the inertia of the convergence of rigid plates and dynamic effects occurring in a thin perfect rigid plastic layer. The second part examines the work related to the formation and development of the neck in plastic materials under quasi-static and dynamic loading. In particular, attention is paid to thin solids with a perturbed boundary shape, which have technological significance. The presence of a small geometric parameter allows using the asymptotic methods.

The safety of space flights is one of the topical issues. It combines a large number of different tasks. The Chair of Gas and Wave Dynamics presents several areas of work in this field. A study of cracks is proposed, because their appearance in the spacecraft skin can lead to an accident. A large number of experiments are being conducted on the ISS to refine mathematical models of media and processes, as well as the physical constants included in them. So, in emergency situations, fires may occur on the ISS. For their modeling, the cases of the presence of both one and several independent gross reactions describing the chemical interaction of an oxidizer with a fuel are considered. The results were compared with FLEX experiments on the combustion of single droplets in zero gravity. In order to refine the filtration models, experiments conducted under microgravity conditions have been studied.

An overview of recent works in the field of gas dynamics and plasma dynamics, which were initiated by Academician L.I. Sedov and his descendants, is given. An analytical study of the equations was carried out, exact solutions were constructed, and the problem of energy-momentum concentration was solved. Higher invariants of characteristics for a system of equations of one-dimensional gas dynamics in Eulerian and Lagrangian variables for special adiabatic exponents are found. Based on the use of higher invariants of characteristics, the solution of the Cauchy problem is reduced to a system of ordinary differential equations. Two Cauchy problems are presented, the solutions of which exist indefinitely without a gradient catastrophe.

Problems related to cosmic gasdynamic studies at the Chair of Aeromechanics and Gasdynamics of Lomonosov Moscow State University are discussed. We give main directions and methods of the space studies at our chair. Results of the developed theoretical models describing and predicting physical phenomena in space are presented in details. The models include the interaction of the solar wind with the local interstellar medium and comet atmospheres, motions of the interstellar medium under nonequilibrium ionization.

In the paper, scientific and pedagogical activities of the Chair of Theoretical Mechanics and Mechatronics of the Faculty of Mechanics and Mathematics of Lomonosov Moscow State University have been described. Some scientific results obtained in recent years by current employees and the most significant scientific results of former employees of the chair have been presented.

The article shows an experimental (part 2) improvement in thestabilization of the gaze under galvanic vestibular stimulation.

The oscillating linear time-invariant system of second order with time-varying bounded control is considered. The reachable set size is studied with respect to bounded parameters of the system. The reachable set size is characterized by a distance from the origin to the most or least distant point of the set in the Euclidean norm. For one case study, the set size is found to be monotonous in all parameters of the system.

In this paper, we present an invariant formulation of the d’Alambert principle and classical time-dependent Lagrangian mechanics with holonomic constraints from the perspective of moving frames.

An algorithm is proposed to determine failures for a redundant inertial sensor unit by means of the guaranteeing estimation method. The numerical testing confirms the efficiency of the proposed algorithm.

The problem of a symmetric stationary cavitation flow around a cylinder by an infinite flow of ideal incompressible weightless fluid in the presence of a given intensity point effluent located at the front point of the cylinder is considered. The exact solution to the problem is constructed by mapping the areas of change in the complex potential and complex flow velocity onto the area of change in the auxiliary parametric variable. A parametric analysis of the problem is performed. For a wide range of values of the cavitation number, the dimensionless flow rate, the shape and dimensions of the cavitation cavity, and the values of the drag coefficient are found.