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Том 72, № 2 (2017)
- Год: 2017
- Статей: 4
- URL: https://journals.rcsi.science/0027-1330/issue/view/10009
Article
Sliding a body on snow
Аннотация
Snow is considered as an ideal nonlinear elastoplastic medium. A body performs planeparallel motion on snow. The area of its contact with snow is a part of a rectangular plate. The contact zone changes during the motion of the body. Steady motions are found from the derived equations of motion in the case when the constant external forces and the moment exerted on the body are given. The inverse problem of determining the forces and moments is solved for a given steady motion of a vehicle.
29-33
A fluid-saturated porous medium under the action of a moving concentrated load
Аннотация
The problem of motion of a concentrated load along the surface of a fluid-saturated porous medium is studied for a subsonic range of speeds. An analytical solution is found. It is shown that there exists a critical speed equal to the speed of the Rayleigh-type surface waves in a porous elastic medium. If this critical speed is exceeded, then the behavior of the solution and the free surface shape are changed. The free surface shape is analyzed at different speeds.
34-39
Noise parameter identification for video tracking systems
Аннотация
The appearance of noises in output records is analyzed for the following movement video tracking systems: Qualisys Oqus, Vicon Bonita, and ARTTRACK2. The static and kinematic noise components are distinguished and their parameters are proposed to identify by comparing with model movements. The comparative evaluation of these systems shows their satisfactory quality in the registration of movements with a velocity up to 6 m/s and with impact interactions with a surrounding medium. The obtained noise samples are used to compare these video tracking systems.
40-47
Heat propagation in a nonuniform rod of variable cross section
Аннотация
An integral formula is used to average a coupled problem of thermoelasticity for a nonuniform rod of variable cross section. Effective characteristics are found. It is shown that, in addition to the expected effective coefficients, there appear five independent coefficients characterizing the temperature change rate effect on the stresses in the rod, on the longitudinal heat flux, and on the entropy distribution along the length of the rod. A feature of these new coefficients is that they become equal to zero in the case of a uniform rod. The homogenization of the thermoelasticity equations for nonuniform rods allows one to propose a new theory of heat conduction in rods. This new theory differs from the classical one by the fact that some new terms are added to the Duhamel–Neumann law, to the Fourier heat conduction law, and to the entropy expression. These new terms are proportional to the temperature change rate with time. It is also shown that, in the new theory of heat conduction, the propagation velocity of harmonic heat perturbations is dependent on the oscillation frequency and is finite when the frequency tends to infinity.
48-53