... On Dug a Nonlinear Interaction of Low Frequensy Sound Waves From the Broadband Source Under Their Anomalous Spreading on Shalow Water . ... In work are considered some regularities of such excitement and spreading a low frequency sound. ...
... On Generation of Infrasound by Large Objects Falling Into Water . L.A.Ostrovsky (Zel technologies/NOAA ETL and Institute of Applied Physics, Boulder, Colorado, USA); A.J.Bedard (NOAA ETL, Boulder, Colorado, USA) . ... Here we consider an important case: an object like a rock or ice shelf falls into water to generate an infrasound. ... It is shown that water surface displacements are able to radiate infrasound with measurable intensity both in air and water. ...
... On Nonlinear Acoustics Methods in Medical Diagnostics . ... This presentation is aiming at exploring new medical applications of nonlinear acoustics based approaches. ... Nonlinear Wave Modulation Spectroscopy (NWMS): a vibration induced ultrasound modulation technique is proposed for detection of bone abnormalities and assessment of bone aging-related changes in bone quality and fracture risk. ... A method for remote non-invasive assessment of the blood pressure was investigated. ...
... On Nonlinear Scattering of Sound by Small Bubble in Polymeric Liquid . ... The presence of free gas in polymers even in small amounts may lead to drastic changes both in technological processes and properties of final products. ... The results of simulations have showed that hereditary properties of the liquid highly influence the scattered signal and must be accounted for at acoustic measurements of bubble population in polymeric liquids. ...
... On Some Applications of Differential Invariants of a Family of Nonlinear Wave Equations . ... It is worthwhile noting that the knowledge of invariants of families of equations is essential for the problem of group classification. ... M. Torrisi, R. Tracina', A. Valenti, On equivalence transformations applied to a non-linear wave equation, Modern Group Analysis: Advanced Analytical and Computational Methods in Mathematical Physics, Kluwer Academic Publishers, 1993, 367-375. ...
... V.M.Fedorchuk (Pidstryhach Institute of Applied Problems of Mechanics and Mathematics of NAS of Ukraine, Lviv, Ukraine); V.I.Fedorchuk (Franko Lviv National University, Lviv, Ukraine.) . ... The subgroup structure of the generalized Poincare group P(1,4) has been studied. ... The results obtained have been used in order to solve the next task: - the symmetry reduction and construction of exact solutions for some linear and nonlinear differential equations in the spaces M(1,4)xR(u) and M(1,3)xR(u)....
... On Some Class of Factorized Dynamical Systems and Their Integrability . ... There is studied the algebraic structure of a class of operatorial evolution equations factorizing standard Lax type integrable flows on the adjoint space to a Lie algebra of pseudo-differential operators. We found the corresponding Poisson structure on the corresponding subgroup Lie, constructed an infinite hierarchy of conservation laws. ...
... On Symmetry Group Extension and Vorticity Conservation in Continuum Mechanics . ... Examples of many Lagrange's hydrodynamic systems show that often in medium motion the conservation of the curl of certain covector takes place. Moreover this covector can be unequal to the medium velocity. ... In general case the Lagrange function can be always reduced to such form by a special extension of sought function set, moreover without presence of unnecessary information. ...
... On a Classification of Orbits for Cubic Differential Systems . M.Popa, E.Naidenova (Academy of Sciences, Institute of Mathematics and Computer Sciences, Kishinev, Moldova) . ... We consider a two-dimensional system of differential equations of the first order with polynomial right . ... Using the methods described in [1] the complete classification of orbits for linear representation of the group of rotations and Lorentz group in the space of coefficients of the cubic differential system is done. ...
... On a Resonant Properties of Magma Structures of the Elbrus Volcano . ... It has been shown that a cavity in a layered half-space is responsible for reradiation of a secondary wave field. Theoretical study reveals eigen frequencies of oscillations of a cavity, excited by a harmonical wave or a pulse, in a half-space. It has been shown that distant earthquakes may excite eigen oscillations of the magma chamber and the magma source of the Elbrus Volcano. ... The frequency range (70 . ...
... This contribution investigates the finite amplitude standing wave generated in a closed pipe by a transient source when its instantaneous frequency varies and successively meets a set of resonance frequencies. ... Based on the well known nonlinear Burgers equation governing nonlinear propagation in viscous media, a new updated incident wave schema is developed and its efficiency to compute the nonlinear resonance modes of a closed tube is demonstrated. ...
... We consider a set of invariant travelling wave (TW) solutions for two modelling systems, simulating long non-linear waves propagation in structured media. Using the methods of local non-linear analysis and numerical simulation, we show that in both cases the set of TW solutions contains localized soliton-like regimes, corresponding to homoclinic loops of three-dimensional dynamical systems obtained from the initial systems of PDE through the group theory reduction. ...
... On the Origin of Dynamic Elastic Nonlinear Behavior in Solids . ... It has recently become clear that a large category of materials exhibit an identical, nonlinear elastic signature [R.A.Guyer and P.A.Johnson, Physics Today Apr. ... These materials (rocks, sand, cement, concrete and ceramics) have been termed nonlinear mesoscopic elastic (NME) materials, in contrast to the well-known nonlinear atomic elastic (AEE) materials . ...
... On the Parallels Between the Control by a Periodic Action of Jet Turbulence and Noise-Induced Oscillations of a Pendulum . ... Our extensive investigations have shown that there are surprising profound parallels between turbulent processes in jets and noise-induced oscillations of a pendulum with a randomly vibrated suspension axis. Especially this touches on how the jets and such a pendulum respond to a periodic external action. ...
... A.Merlen (Laboratoire de Mecanique de Lille (LML-URA CNRS 1441), Villeneuve d'Ascq, France); V.Preobrazhensky (Institut d'Electronique et de Micro-electronique du Nord (IEMN-DOAE-UMR CNRS 8520), Ecole Centrale de Lille, Villeneuve d'Acsq, France, and Wave Research Center of General Physics Institute RAS, Moscow, Russia); P.Pernod (Institut d'Electronique et de Micro-electronique du Nord (IEMN-DOAE-UMR CNRS 8520), Ecole Centrale de Lille, Villeneuve d'Acsq, France) . ...
... Mech. 1997, v. 344, p. 339] that the asymptotic form of the spectrum is self-similar and depends only on two integral parameters of the initial spectrum: the variance of the velocity and its spatial scale. Moreover, widely different initial conditions having the same value of these parameters could converge to the same asymptotic state, without any rescaling of this state. This prediction is checked numerically and found to be valid for sufficiently steep initial spectra. ...
... Optical-Acoustic Spectroscopy of Structural Changes in Metals Under Shock Loading . ... The results of experimental investigations of metal structure changes by a optical.acoustic spectroscopy method are submitted. Iron and nickel samples subjected to vacuum annealing at different temperatures were investigated. ... In samples with the different grain size the plastic deformation in a loading zone leads to reorganization of structure completed at different scale levels. ...
... Optimal System and Group Invariant Solutions for a Nonlinear Wave Equation . ... The mathematical model is one-dimensional and it is in the form of a third order nonlinear partial differential equation describing the two-phase fluid flow of a medium compacting under gravity. ... We derive the one dimensional optimal system of the partial differential equation by using techniques developed by Olver [1986], Coggeshall and Meyer-ter-vehn [1992] and Chupakhin [1994]. ...
... Optimization of Long Low-Sized Silted Objects Search at Parametric Survey of Sea Bottom . ... The problem of hydroacoustic location of long low-sized silted objects using parametric means of bottom survey is investigated. ... The questions of low-sized silted objects search using local resonances and also problem of synchronization between resonant formations in bottom structures are discussed. ...
... Opto-Acoustic Response From Absorbed Particle in Liquid . ... This work is devoted to a theoretical analysis of the opto-acoustic effect in an inhomogeneous medium consisting of an absorbing spherical particle in an immersion (nonabsorbing) liquid irradiated with laser pulses. ... In the case of a thermally small particle, a heating of a particle takes place uniformly at its volume and the opto-acoustic pulse is excited only by thermal expansion of immersed layer of liquid. ...