Applied Mechanics and Materials Vol. 756

Abstract: The cloaking problem is considered for a 2-D wave scattering model in an unbounded homogenous medium containing an impenetrable covered (cloaked) boundary. The control is a surface impedance which enters the boundary condition as a coefficient. The problem is reduced to the inverse extremal problem of choosing the surface impedance. The solvability of the original scattering problem for 2-D Helmholtz equation and of the extremal problem is proved. Optimality system describing the necessary extremum conditions is derived. The algorithm for numerical solving of the control problem based on the optimality system and boundary element method is designed.

Abstract: To study the behavior of materials with special properties, such as micro and nanograin structure, it is necessary to know how the size and the form of grain influences on the effective properties of the material. In particular, for materials with fine-dispersed structure characterized by high mass transfer rate, which could be due to several reasons. To study this kind of materials is necessary to build mathematical models taking into account the peculiarities that arise from the transition to the micro structure of the macrostructure. This paper presents a method of calculating the effective diffusion coefficient, which takes into account the influence of the size and form of grains. This method could be useful for the construction of multilayer models of mass transfer. On the example of hexagonal polycrystalline material shown that the dependence of the effective diffusion coefficient of the angle at the grain boundary acquires nonlinear character with the increase of grain boundary layer.

Abstract: The mathematical model of pulsed electric-sintering powder compositions are suggested and investigated. The distribution temperature, density and speed and thickness the powder composition studied.

Abstract: Multilayer protective materials and coatings attract attention last years because the possibility appears to obtain unique properties of materials due to combination of properties and sizes of layers. In his paper analytical solution is constructed for the problem on multilayer foil tension. It is assumed that stress and strain tensor components depend on one space coordinate in the axis direction perpendicular to layers and generalized plane stressed state is realized. Interesting effect is detected for two-layer material: thickness of the coating exists when one of diagonal stress tensor components is minimal, that ensure minimal break in the corresponding stresses in interface. This effect is observed previously experimentally by many authors. However, other diagonal component of stress tensor has maximal value for other value of coating thickness. The positions of the maximal and minimal values of stresses and breaks depend on combination of properties and thicknesses of layers.

Abstract: Capacitance per unit length and related wave resistance refer to the main characteristics of a number of cable products, such as communication cables, control cables or radio-frequency cables. The capacitance per unit length value is regulated by the standards for appropriate types of cables. This study describes the technical implementation of the electrical method of measuring of the capacitance per unit length of the electric cable directly on the production line. It is shown that the change in specific electrical conductivity of water, which a capacitance transducer is dipped into, has a significant impact on the outcome of in-process control of cable capacitance per unit length. A method of offset from the impact of this measurement on the control results is suggested.

Abstract: In this paper we find a general solution for the action function in the case of a heavy point moving on a sphere using the method of separation of the Hamilton-Jacobi equation variables. The solution contains two constants: the energy of a material point and the momentum projection onto a horizontal direction. We analyze the modes of a spherical pendulum oscillation. It is shown that the solution does not contain any errors of accumulation which are characteristic for evolution problems with long prediction periods.

Abstract: A new method of the data measurement and processing for the centerless roundness measuring of components with the use of corrective adjustment is proposed. There are scientific explanations for mathematical simulation which includes numerical methods and harmonic analysis and also considers the change of the contact points of the product and prism faces during rotation. The methodical error and the evaluation of the centerless roundness measurements are determined according to the practical measurements and the model analysis.

Abstract: This article is devoted to review of the existing mobile water treatment complex. Development of resource-efficient technology for water purification is examined by the change of process chart as a function of qualitative composition of a water source. Machine design variants are proposed on the terrain vehicle.

Abstract: The method of control system object positioning, wherein the control signals generating is based on the analysis of the direct action of the operator on the object. Object positioning system scheme is designed for realization of the proposed method. The procedure of object positioning is engineered.

Abstract: Getting fast and accurate information is of paramount importance for most monitoring, data acquisition, and monitoring systems; there are sensors that transform their input into a frequency domain output, this kind of sensors are known as Frequency Domain Sensors (FDS); when the value of the output frequency is measured in a FDS, the value of the sensor’s input (measurand) can be calculated, that is why the frequency measurement in the output of FDS is critical for using such sensors. In this work different kinds of resonant sensors (FDS) are reviewed; also frequency measurement techniques are explored; finally a novel frequency measurement method is proposed and analyzed for resolution improvement in frequency domain sensors.