Self-excited vibrations are observed in many technical applications. Frictional contacts are often involved in the mechanism which generates vibrations. Reasons for the excitation mechanisms are decreasing friction characteristics depending on the sliding velocity, fluctuating normal loads or different geometrical effects. First, the mechanisms are explained using simple examples. The practical...

Our aim is to show the possibility of a "vibrational Fréedericksz's transition" in nematic liquid crystals (LCs) consisting of asymmetric molecules (in the absence of the reflectional symmetry for the director field). For this purpose we study the effects of the external high-frequency vibrations imposed on LCs by employing the rigorous two-timing asymptotic averaging method to the governing LC...

In order to effectively control vibration related problems, the development of a reliable vibration monitoring system and the proper assessment of attenuation characteristics of various vibrations are essential. Various ground vibrations caused by train loading, blasting, friction pile driving and hydraulic hammer compaction were measured using 3D geophones inside of the borehole as well as on ...

In this study, two experiments were conducted to determine the curves of equal intensity perception for sinusoidal vertical whole-body vibrations (WBV) of seated subjects over the frequency range from 10Hz to 250Hz. Vibrations were presented to subjects using a at hard seat. In total, 10 participants were asked to match the intensity of di erent vibrations, using a method of adjustment. The obt...

The physical mechanism by which cells sense high-frequency mechanical signals of small magnitude is unknown. During exposure to vibrations, cell populations within a bone are subjected not only to acceleratory motions but also to fluid shear as a result of fluid-cell interactions. We explored displacements of the cell nucleus during exposure to vibrations with a finite element (FE) model and te...

in this paper, a rectangular sandwich plate with a constrained layer and an electrorheological (er) fluid core is investigated. the rectangular plate is covered an er fluid core and a constraining layer to improve the stability of the system. the two outer layers of the sandwich structure are elastic. the viscoelastic materials express the middle layer behavior under electric field and small st...

This paper presents the application of a time-delay neural network to the detection and classification of time signatures produced by insect sounds in a stored grain silo. Conventional methodr of insect monitoring can only detecr some of rhe adulr insects and none of the larvae insects, which are the most destructive to the grain. The acoustic vibrations generated by the adult and larvae when m...

A Fermi resonance-algebraic model is proposed for molecular vibrations, where a U(2) algebra is used for describing the vibrations of each bond, and Fermi resonances between stretching and bending modes are taken into account. The model for a bent molecule XY2 and a molecule XY3 is successfully applied to fit the recently observed vibrational spectrum of the water molecule and arsine (AsH3), re...

The nonlinear two-degree-of-freedom system under consideration consists of the linear oscillator with a relatively big mass, which is an approximation of some continuous elastic system, and of the vibro-impact oscillator with a relatively small mass, which is an absorber of the linear system vibrations. Analysis of nonlinear normal vibration modes shows that a stable localized vibration mode, w...

The problem of stabilizing vibrations of flexible cable related to an overhead crane is considered. The cable vibrations are described by a hyperbolic partial differential equation HPDE with an update boundary condition. We provide in this paper a systematic way to derive a boundary feedback law which restores in a closed form the cable vibrations to the desired zero equilibrium. Such a control...