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Optimization of the semi-active vibration absorbers

Snitynskyy Volodymyr, Kernytskyy Ivan, Diveyev Bohdan, Horbay Orest, Fornalchyk Yevhen, Humenuyk Ruslan, Sholudko Yaroslav

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2021

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Vol. 30, No. 2

327--336

EN

In this paper, an efficient numerical approach is proposed to maximize the minimal damping of modes in a prescribed frequency range for general viscous tuned-mass systems. Methods of decomposition and numerical synthesis are considered on the basis of the adaptive schemes. The influence of dynamic vibration absorbers and basic design elastic and damping properties is under discussion. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in sinusoidal and impact forced system. One task of this work is to analyze parameters identification of the dynamic vibration absorber and the basic structure. The questions of robustness at optimization of DVA are considered. Different types of control management for semi-active DVA’s are applied. Examples of DVA’s practical implementation are presented.

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Prospects of electrosleep therapy devices for long-distance drivers

Kernytskyy Ivan, Storchun Yevhen, Yakovenko Yevheniia, Horbay Orest, Humenuyk Ruslan, Sholudko Yaroslav

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2020

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Vol. 29, No. 4

454--460

EN

Accomulated exhaustion is a fairly common problem for long-distance truck and bus drivers on international routes. In case of uncompensated exhaustion, the driver is unable to overcome the resulting attention violations with will effort, which increases the probability of errors and accidents. The last claim is confirmed by the increase in the number of incidents after 7 h and especially 10 h of work. To overcome this problem, it is necessary to stop and fall asleep for a short time. Recovery comes in about 10–15 min of relaxation. The source of stimulation of the brain is weak impulse current, which causes sleep of varying depth and duration. Clinical studies have shown that the strongest impact is on pulses with a duration of approximately 0.3– –0.5 ms and a frequency of repetition ranging from 0.5–2 to 80–100 Hz. Current levels are typically between 50 and 5 mA. Transcranial electrotherapy is considered to stimulate endorphin production and affect the hypothalamus, causing changes in neurohormonal regulatory mechanisms and reticular formation of the brain stem. The reticular formation is involved in many behavioral reactions and has a significant impact on body functioning and thought processes. The aim of this work was to determine correlation between human brain biorhythms and electrosleep device signal by calculating mutual correlation. For this purpose, the model in MATLAB Simulink environment was developed. The encephalogram was processed using the EEGLAB tool to remove artifacts. A model in the MATLAB Simulink environment was developed to evaluate the effect of the signal characteristics of electrosleep therapy devices on brain biorhythms, with the help of which correlation coefficients were calculated.

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Dynamic properties of screw-bolts connections of sowing machine

Snitynskyy Volodymyr, Kernytskyy Ivan, Diveyev Bohdan, Horbay Orest, Burtak Volodymyr, Humenyuk Ruslan

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2019

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Vol. 28, No. 4

584--593

EN

A vehicle is a complicated system under the influence of vibration caused by an inequality of the road surface, variable speed, unbalance of the rotating elements. The main factors influencing the relaxation of threaded connections (TC) are the amplitude, frequency and gradient of vibration. Although the frequencies of these oscillations are distributed over a wide range, the general effects of dynamic loading on bolted connections are similar. Main effects: (1) loosening the nut/bolt and (2) failure due to fatigue failure. The analysis of the technological process of agricultural machinery shows that the main external factors influencing their work are the profile of the surface of the field, the hardness and moisture of the soil, the speed of the unit, the instability of the engine, the traction of the wheels of the tractor and others. To study the integrity of TC, which is tested on the stand, consider the design scheme of nonlinear oscillations of the design in the presence of gaps in the TC. The study was conducted in two modes of movement of the drill: with tightened bolts and weakened bolts. For the survey, the method of spectral analysis of multidimensional periodically non-stationary random signals was used. In the process of testing, the dynamic loading of bolted joints installed on the respective knots and components of the drill was evaluated. From the conducted research it follows that the maximum vibrations acting on the TC of the drill may be in the vicinity of high-frequency resonances of TC. In parallel, nonlinear mathematical models of the oscillations of the seeder and the weakened TC were developed. The theoretical results qualitatively correspond to the experimental data.