Material Science, Engineering and Applications
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Development of smart membrane valve based on geometric moiré interferometry
Full text linkNovel smart membrane valve which functionality is based on optical interference effects caused by moiré interferometry is proposed in this paper. The membrane is comprised from two steel gratings. Geometrical adjustment between adjacent holes in both membranes results in zero flow rate through the valve when no control signal is activated. Rotation of the control membrane generates moiré interference effects which are exploited for flow control. Relationships between the shape and geometric locations of the moiré circles and the control parameters of the second membrane are determined what helps to implement optimal valve control strategie
Chain type system with wave excitation
Full text linkVarious systems based on waves and vibrations are used for displacing, grouping, classification of multidimensional media and bodies. This paper deals with such wave operation based systems augmented by self-stopping elements which ensure one-directional motion of the driven sub-systems. Such enhancements can improve some dynamical characteristics of the analysed systems. The objective of this paper is to develop models of systems and methods of analysis which would help to reveal nonlinear dynamical properties and phenomena of those systems. The conditions of solutions' existence and stability, basin boundaries are determined. Simpler cases are analysed analytically. The obtained relationships provide insight into nonlinear dynamics of complex systems which are analysed numerically
Directional conjugate smoothing for analysis of axi-symmetric fluid vibrations
Full text linkNumerical implementation of the Abel transform for the construction of digital fluid holographic images is analyzed in this paper. Volumetric strains are obtained from the numerical calculations using the displacement formulation by the method of finite elements. Then the field of volumetric strain is obtained by using the procedure of conjugate approximation with smoothing. Numerical procedure is developed for the calculation of the Abel transform on the basis of the right rectangle numerical integration rule and thus the digital holographic image is constructed. The obtained digital holographic images are used in the hybrid experimental – numerical procedure for the determination of the correlation with the experimental holographic image
Researches of temperature influence on parameters of rotor rotation of rotary system
Full text linkRotary systems with bearings of sliding friction are analyzing in this paper. It is researching influence of temperature change on characteristics of work of searching system. It had done experimental researches trying to ascertain how temperatures change is doing influence on parameters of work of rotary systems with bearings of sliding. Experimental measurements are doing by methodology that is making specially, using different transducers of measurement. It is describing and giving principal system of measurement and analysis, its photo, scheme of measurement and methodology of experiments performance. It is getting primary signals of measurement of rotor vibrations, temperature changes and results of analysis are giving in graphs. It is doing analysis of getting results and it is establishing interdependences of searching parameters, their consistent patterns of changes and influence on quality of work of searching syste
Changes of the human gait after total hip joint replacement surgery
Full text linkThe aim of this work was to determine the effect of a hip joint replacement on human locomotion-support apparatus and movement functions. 3D biomechanical model of human locomotion-support system was developed for comparative analysis of the healthy state and the state after total hip replacement operation. The effect of shift of hip joint replacement centre position on human movement and muscles activity patterns was determined by using computational and experimental methods. The results of analysis obtained on the basis of this model and method are presented: it is shown that the change of position of hip joint replacement elements (cup and sphere) has substantial effect on human walking patter
Study of robot actuator operating as a system on air films
Full text linkThe paper analyzes the dynamics of a robot pneumatic actuator. The mechanical system motion is described by a differential equation system when the air flow is expressed by a non-dimensional Prandtl formula. The findings of the digital study are presented. The zones of self-exciting vibrations of the vibrotransducer have been determined, as well as the dependences of amplitudes and frequency upon the supply air pressure. The dependence of the linear movement of the actuator’s gripper device and its velocity on the geometric parameters of the vibrating transducer of the mechanical system is presente
The evaluation of resonant frequencies of rotary system with adaptive segmental sliding bearings by orbits of rotor rotation axis
Full text linkThis paper is based on research of work parameters of rotary systems with segmental sliding bearings, working system in the resonant regime. Primary signals are given doing experimental researches, they are analyzed with special programmable pockets and different formats of data are given. Evaluation of work state of rotary system is done in the resonant and in the normal regime by getting orbits of rotor rotation. The principal scheme of researching system is given in this work and its technical characteristics and principle of working are described. Methodology of experimental researches is given. The gained results are described in graphs and a comparison of obtaining results and its discussio