SOME PROBLEMS WITH THE MATHEMATICAL MODELING OF ELECTROMAGNETIC VIBRATORS USED FOR TRANSPORTING BULK MATERIALS

Mathematical modeling with the original approach is used to study the dynamics of low-frequency electro-vibration machines while taking the technological load into account. Based on the mathematical analysis of differential equations describing the oscillatory motion of electromagnetic vibration exciters, the existing mathematical model has been corrected to describe the action of a semiconductor diode in the power circuits of single-cycle vibrators. Modeling nonlinear dynamic systems reveals the difficulties of obtaining the amplitude-frequency characteristics of the associated discrete change in the frequency of the driving force, as well as ways to overcome them

A new simple method for determining the sound absorption coefficient

Taking into account the influence of the length and diameter of the impedance tube on the process of decay of sound waves, a new study of sound propagation in an impedance tube is presented, on the basis of which it is easier to determine the sound absorption coefficient. The new simple method of determining the absorption coefficient, based on the decay of reverberating waves, is fairly stable and demonstrates a low sensitivity for all errors made in the measurement. The presented method makes it possible to measure the sound absorption coefficient without laboratories and precision measuring instruments in a wide range at the level of separate consumers

Loading and damageability of wheels and rails

Friction, rolling resistance and durability of rails and wheels at operation, belong to a number of the most important problems of railway transportation because they have strong impact on derailment, energy consumption and restorative maintenance. Various aspects of these problems are insufficiently investigated, have only partial solution. The sources of creep and slipping of a wheel on a rail and ways of its reduction are specified in the work. These approaches alongside with the traditional methods (lubrication, radial steering bogie, etc.) will ensure the reduction both the power and the thermal loading of the contact zone and wear rate of rails and wheels